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Sample records for supersonic gaseous flow

  1. Supersonic flows over cavities

    Institute of Scientific and Technical Information of China (English)

    Tianwen FANG; Meng DING; Jin ZHOU

    2008-01-01

    The characteristics of supersonic cold flows over cavities were investigated experimentally and numer-ically, and the effects of cavities of different sizes on super-sonic flow field were analyzed. The results indicate that the ratio of length to depth L/D within the range of 5-9 has little relevance to integral structures of cavity flow. The bevel angle of the rear wall does not alter the overall structure of the cavity flow within the range of 30°-60°, but it can exert obvious effect on the evolvement of shear layer and vortexes in cavities.

  2. Infinitesimal Conical Supersonic Flow

    Science.gov (United States)

    Busemann, Adolf

    1947-01-01

    The calculation of infinitesimal conical supersonic flow has been applied first to the simplest examples that have also been calculated in another way. Except for the discovery of a miscalculation in an older report, there was found the expected conformity. The new method of calculation is limited more definitely to the conical case.

  3. Dynamical friction for supersonic motion in a homogeneous gaseous medium

    CERN Document Server

    Thun, Daniel; Schmidt, Franziska; Kley, Wilhelm

    2016-01-01

    The supersonic motion of gravitating objects through a gaseous medium constitutes a classical problem in theoretical astrophysics. Its application covers a broad range of objects and scales from planets up to galaxies. Especially the dynamical friction, caused by the forming wake behind the object, plays an important role for the dynamics of the system. To calculate the dynamical friction, standard formulae, based on linear theory are often used. It is our goal to check the general validity of these formulae and provide suitable expressions for the dynamical friction acting on the moving object, based on the basic physical parameters of the problem. We perform sequences of high resolution numerical studies of rigid bodies moving supersonically through a homogeneous medium, and calculate the total drag acting on the object, which is the sum of gravitational and hydro drag. We study cases without gravity with purely hydrodynamical drag, as well as gravitating objects. From the final equilibrium state of the sim...

  4. Supersonic flow imaging via nanoparticles

    Institute of Scientific and Technical Information of China (English)

    2009-01-01

    Due to influence of compressibility,shock wave,instabilities,and turbulence on supersonic flows, current flow visualization and imaging techniques encounter some problems in high spatiotemporal resolution and high signal-to-noise ratio(SNR)measurements.Therefore,nanoparticle based planar laser scattering method(NPLS)is developed here.The nanoparticles are used as tracer,and pulse planar laser is used as light source in NPLS;by recording images of particles in flow field with CCD, high spatiotemporal resolution supersonic flow imaging is realized.The flow-following ability of nanoparticles in supersonic flows is studied according to multiphase flow theory and calibrating experiment of oblique shock wave.The laser scattering characteristics of nanoparticles are analyzed with light scattering theory.The results of theoretical and experimental studies show that the dynamic behavior and light scattering characteristics of nanoparticles highly enhance the spatiotemporal resolution and SNR of NPLS,with which the flow field involving shock wave,expansion,Mach disk,boundary layer,sliding-line,and mixing layer can be imaged clearly at high spatiotemporal resolution.

  5. Supersonic Plasma Flow Control Experiments

    Science.gov (United States)

    2005-12-01

    to liquid metals , for example, the conductivities of typical plasma and electrolyte flows are relatively low. Ref. 14 cites the conductivity of...heating is the dominant effect. 15. SUBJECT TERMS Supersonic, plasma , MHD , boundary-layer 16. SECURITY CLASSIFICATION OF: 19a. NAME OF RESPONSIBLE...horns in operation on Mach 5 wind tunnel with a plasma discharge. 31 Figure 17 Front view of a 100 mA DC discharge generated with upstream pointing

  6. Dynamical friction for supersonic motion in a homogeneous gaseous medium

    Science.gov (United States)

    Thun, Daniel; Kuiper, Rolf; Schmidt, Franziska; Kley, Wilhelm

    2016-05-01

    Context. The supersonic motion of gravitating objects through a gaseous ambient medium constitutes a classical problem in theoretical astrophysics. Its application covers a broad range of objects and scales from planetesimals, planets, and all kind of stars up to galaxies and black holes. In particular, the dynamical friction caused by the wake that forms behind the object plays an important role for the dynamics of the system. To calculate the dynamical friction for a particular system, standard formulae based on linear theory are often used. Aims: It is our goal to check the general validity of these formulae and provide suitable expressions for the dynamical friction acting on the moving object, based on the basic physical parameters of the problem: first, the mass, radius, and velocity of the perturber; second, the gas mass density, soundspeed, and adiabatic index of the gaseous medium; and finally, the size of the forming wake. Methods: We perform dedicated sequences of high-resolution numerical studies of rigid bodies moving supersonically through a homogeneous ambient medium and calculate the total drag acting on the object, which is the sum of gravitational and hydrodynamical drag. We study cases without gravity with purely hydrodynamical drag, as well as gravitating objects. In various numerical experiments, we determine the drag force acting on the moving body and its dependence on the basic physical parameters of the problem, as given above. From the final equilibrium state of the simulations, for gravitating objects we compute the dynamical friction by direct numerical integration of the gravitational pull acting on the embedded object. Results: The numerical experiments confirm the known scaling laws for the dependence of the dynamical friction on the basic physical parameters as derived in earlier semi-analytical studies. As a new important result we find that the shock's stand-off distance is revealed as the minimum spatial interaction scale of

  7. Parametric experimental studies on mixing characteristics within a low area ratio rectangular supersonic gaseous ejector

    Science.gov (United States)

    Karthick, S. K.; Rao, Srisha M. V.; Jagadeesh, G.; Reddy, K. P. J.

    2016-07-01

    We use the rectangular gaseous supersonic ejector as a platform to study the mixing characteristics of a confined supersonic jet. The entrainment ratio (ER) of the ejector, the non-mixed length (LNM), and potential core length (LPC) of the primary supersonic jet are measures to characterize mixing within the supersonic ejector. Experiments are carried out on a low area ratio rectangular supersonic ejector with air as the working fluid in both primary and secondary flows. The design Mach number of the nozzle (MPD = 1.5-3.0) and primary flow stagnation pressure (Pop = 4.89-9.89 bars) are the parameters that are varied during experimentation. Wall static pressure measurements are carried out to understand the performance of the ejector as well as to estimate the LNM (the spatial resolution is limited by the placement of pressure transducers). Well-resolved flow images (with a spatial resolution of 50 μm/pixel and temporal resolution of 1.25 ms) obtained through Planar Laser Mie Scattering (PLMS) show the flow dynamics within the ejector with clarity. The primary flow and secondary flow are seeded separately with acetone that makes the LNM and LPC clearly visible in the flow images. These parameters are extracted from the flow images using in-house image processing routines. A significant development in this work is the definition of new scaling parameters within the ejector. LNM, non-dimensionalized with respect to the fully expanded jet height hJ, is found to be a linear function of the Mach number ratio (Mach number ratio is defined as the ratio of design Mach number (MPD) and fully expanded Mach number (MPJ) of the primary jet). This definition also provides a clear demarcation of under-expanded and over-expanded regimes of operation according to [MPD/MPJ] > 1 and [MPD/MPJ] < 1, respectively. It is observed that the ER increased in over-expanded mode (to 120%) and decreased in under-expanded mode (to 68%). Similarly, LNM decreased (to 21.8%) in over-expanded mode

  8. Turbulent Shear Layers in Supersonic Flow

    CERN Document Server

    Smits, Alexander J

    2006-01-01

    A good understanding of turbulent compressible flows is essential to the design and operation of high-speed vehicles. Such flows occur, for example, in the external flow over the surfaces of supersonic aircraft, and in the internal flow through the engines. Our ability to predict the aerodynamic lift, drag, propulsion and maneuverability of high-speed vehicles is crucially dependent on our knowledge of turbulent shear layers, and our understanding of their behavior in the presence of shock waves and regions of changing pressure. Turbulent Shear Layers in Supersonic Flow provides a comprehensive introduction to the field, and helps provide a basis for future work in this area. Wherever possible we use the available experimental work, and the results from numerical simulations to illustrate and develop a physical understanding of turbulent compressible flows.

  9. ARBITRARY INTERACTION OF PLANE SUPERSONIC FLOWS

    Directory of Open Access Journals (Sweden)

    P. V. Bulat

    2015-11-01

    Full Text Available Subject of study.We consider the Riemann problem for parameters at collision of two plane flows at a certain angle. The problem is solved in the exact statement. Most cases of interference, both stationary and non-stationary gas-dynamic discontinuities, followed by supersonic flows can be reduced to the problem of random interaction of two supersonic flows. Depending on the ratio of the parameters in the flows, outgoing discontinuities turn out to be shock waves, or rarefactionwaves. In some cases, there is no solution at all. It is important to know how to find the domain of existence for the relevant decisions, as the type of shock-wave structures in these domains is known in advance. The Riemann problem is used in numerical methods such as the method of Godunov. As a rule, approximate solution is used, known as the Osher solution, but for a number of problems with a high precision required, solution of this problem needs to be in the exact statement. Main results.Domains of existence for solutions with different types of shock-wave structure have been considered. Boundaries of existence for solutions with two outgoing shock waves are analytically defined, as well as with the outgoing shock wave and rarefaction wave. We identify the area of Mach numbers and angles at which the flows interact and there is no solution. Specific flows with two outgoing rarefaction waves are not considered. Practical significance. The results supplement interference theory of stationary gas-dynamic discontinuities and can be used to develop new methods of numerical calculation with extraction of discontinuities.

  10. Particle Streak Velocimetry of Supersonic Nozzle Flows

    Science.gov (United States)

    Willits, J. D.; Pourpoint, T. L.

    2016-01-01

    A novel velocimetry technique to probe the exhaust flow of a laboratory scale combustor is being developed. The technique combines the advantages of standard particle velocimetry techniques and the ultra-fast imaging capabilities of a streak camera to probe high speed flows near continuously with improved spatial and velocity resolution. This "Particle Streak Velocimetry" technique tracks laser illuminated seed particles at up to 236 picosecond temporal resolution allowing time-resolved measurement of one-dimensional flows exceeding 2000 m/s as are found in rocket nozzles and many other applications. Developmental tests with cold nitrogen have been performed to validate and troubleshoot the technique with supersonic flows of much lower velocity and without background noise due to combusting flow. Flow velocities on the order of 500 m/s have been probed with titanium dioxide particles and a continuous-wave laser diode. Single frame images containing multiple streaks are analyzed to find the average slope of all incident particles corresponding to the centerline axial flow velocity. Long term objectives for these tests are correlation of specific impulse to theoretical combustion predictions and direct comparisons between candidate green fuels and the industry standard, monomethylhydrazine, each tested under identical conditions.

  11. Chemically reacting supersonic flow calculation using an assumed PDF model

    Science.gov (United States)

    Farshchi, M.

    1990-01-01

    This work is motivated by the need to develop accurate models for chemically reacting compressible turbulent flow fields that are present in a typical supersonic combustion ramjet (SCRAMJET) engine. In this paper the development of a new assumed probability density function (PDF) reaction model for supersonic turbulent diffusion flames and its implementation into an efficient Navier-Stokes solver are discussed. The application of this model to a supersonic hydrogen-air flame will be considered.

  12. Numerical simulation of supersonic gap flow.

    Science.gov (United States)

    Jing, Xu; Haiming, Huang; Guo, Huang; Song, Mo

    2015-01-01

    Various gaps in the surface of the supersonic aircraft have a significant effect on airflows. In order to predict the effects of attack angle, Mach number and width-to-depth ratio of gap on the local aerodynamic heating environment of supersonic flow, two-dimensional compressible Navier-Stokes equations are solved by the finite volume method, where convective flux of space term adopts the Roe format, and discretization of time term is achieved by 5-step Runge-Kutta algorithm. The numerical results reveal that the heat flux ratio is U-shaped distribution on the gap wall and maximum at the windward corner of the gap. The heat flux ratio decreases as the gap depth and Mach number increase, however, it increases as the attack angle increases. In addition, it is important to find that chamfer in the windward corner can effectively reduce gap effect coefficient. The study will be helpful for the design of the thermal protection system in reentry vehicles.

  13. Numerical simulation of supersonic gap flow.

    Directory of Open Access Journals (Sweden)

    Xu Jing

    Full Text Available Various gaps in the surface of the supersonic aircraft have a significant effect on airflows. In order to predict the effects of attack angle, Mach number and width-to-depth ratio of gap on the local aerodynamic heating environment of supersonic flow, two-dimensional compressible Navier-Stokes equations are solved by the finite volume method, where convective flux of space term adopts the Roe format, and discretization of time term is achieved by 5-step Runge-Kutta algorithm. The numerical results reveal that the heat flux ratio is U-shaped distribution on the gap wall and maximum at the windward corner of the gap. The heat flux ratio decreases as the gap depth and Mach number increase, however, it increases as the attack angle increases. In addition, it is important to find that chamfer in the windward corner can effectively reduce gap effect coefficient. The study will be helpful for the design of the thermal protection system in reentry vehicles.

  14. Stationary flow conditions in pulsed supersonic beams.

    Science.gov (United States)

    Christen, Wolfgang

    2013-10-21

    We describe a generally applicable method for the experimental determination of stationary flow conditions in pulsed supersonic beams, utilizing time-resolved electron induced fluorescence measurements of high pressure jet expansions of helium. The detection of ultraviolet photons from electronically excited helium emitted very close to the nozzle exit images the valve opening behavior-with the decided advantage that a photon signal is not affected by beam-skimmer and beam-residual gas interactions; it thus allows to conclusively determine those operation parameters of a pulsed valve that yield complete opening. The studies reveal that a "flat-top" signal, indicating constant density and commonly considered as experimental criterion for continuous flow, is insufficient. Moreover, translational temperature and mean terminal flow velocity turn out to be significantly more sensitive in testing for the equivalent behavior of a continuous nozzle source. Based on the widely distributed Even-Lavie valve we demonstrate that, in principle, it is possible to achieve quasi-continuous flow conditions even with fast-acting valves; however, the two prerequisites are a minimum pulse duration that is much longer than standard practice and previous estimates, and a suitable tagging of the appropriate beam segment.

  15. Drag Force Anemometer Used in Supersonic Flow

    Science.gov (United States)

    Fralick, Gustave C.

    1998-01-01

    To measure the drag on a flat cantilever beam exposed transversely to a flow field, the drag force anemometer (beam probe) uses strain gauges attached on opposite sides of the base of the beam. This is in contrast to the hot wire anemometer, which depends for its operation on the variation of the convective heat transfer coefficient with velocity. The beam probe retains the high-frequency response (up to 100 kHz) of the hot wire anemometer, but it is more rugged, uses simpler electronics, is relatively easy to calibrate, is inherently temperature compensated, and can be used in supersonic flow. The output of the probe is proportional to the velocity head of the flow, 1/2 rho u(exp 2) (where rho is the fluid density and u is the fluid velocity). By adding a static pressure tap and a thermocouple to measure total temperature, one can determine the Mach number, static temperature, density, and velocity of the flow.

  16. Supersonic Magnetic Flows in the Quiet Sun

    CERN Document Server

    Borrero, J M; Schlichenmaier, R; Schmidt, W; Berkefeld, T; Solanki, S K; Bonet, J A; Iniesta, J C del Toro; Domingo, V; Barthol, P; Gandorfer, A

    2012-01-01

    In this contribution we describe some recent observations of high-speed magnetized flows in the quiet Sun granulation. These observations were carried out with the Imaging Magnetograph eXperiment (IMaX) onboard the stratospheric balloon {\\sc Sunrise}, and possess an unprecedented spatial resolution and temporal cadence. These flows were identified as highly shifted circular polarization (Stokes $V$) signals. We estimate the LOS velocity responsible for these shifts to be larger than 6 km s$^{-1}$, and therefore we refer to them as {\\it supersonic magnetic flows}. The average lifetime of the detected events is 81.3 s and they occupy an average area of about 23\\,000 km$^2$. Most of the events occur within granular cells and correspond therefore to upflows. However some others occur in intergranular lanes or bear no clear relation to the convective velocity pattern. We analyze a number of representative examples and discuss them in terms of magnetic loops, reconnection events, and convective collapse.

  17. Gaseous Nitrogen Orifice Mass Flow Calculator

    Science.gov (United States)

    Ritrivi, Charles

    2013-01-01

    The Gaseous Nitrogen (GN2) Orifice Mass Flow Calculator was used to determine Space Shuttle Orbiter Water Spray Boiler (WSB) GN2 high-pressure tank source depletion rates for various leak scenarios, and the ability of the GN2 consumables to support cooling of Auxiliary Power Unit (APU) lubrication during entry. The data was used to support flight rationale concerning loss of an orbiter APU/hydraulic system and mission work-arounds. The GN2 mass flow-rate calculator standardizes a method for rapid assessment of GN2 mass flow through various orifice sizes for various discharge coefficients, delta pressures, and temperatures. The calculator utilizes a 0.9-lb (0.4 kg) GN2 source regulated to 40 psia (.276 kPa). These parameters correspond to the Space Shuttle WSB GN2 Source and Water Tank Bellows, but can be changed in the spreadsheet to accommodate any system parameters. The calculator can be used to analyze a leak source, leak rate, gas consumables depletion time, and puncture diameter that simulates the measured GN2 system pressure drop.

  18. NASA F-16XL supersonic laminar flow control program overview

    Science.gov (United States)

    Fischer, Michael C.

    1992-01-01

    The viewgraphs and discussion of the NASA supersonic laminar flow control program are provided. Successful application of laminar flow control to a High Speed Civil Transport (HSCT) offers significant benefits in reductions of take-off gross weight, mission fuel burn, cruise drag, structural temperatures, engine size, emissions, and sonic boom. The ultimate economic success of the proposed HSCT may depend on the successful adaption of laminar flow control, which offers the single most significant potential improvements in lift drag ratio (L/D) of all the aerodynamic technologies under consideration. The F-16XL Supersonic Laminar Flow Control (SLFC) Experiment was conceived based on the encouraging results of in-house and NASA supported industry studies to determine if laminar flow control is feasible for the HSCT. The primary objective is to achieve extensive laminar flow (50-60 percent chord) on a highly swept supersonic wing. Data obtained from the flight test will be used to validate existing Euler and Navier Stokes aerodynamic codes and transition prediction boundary layer stability codes. These validated codes and developed design methodology will be delivered to industry for their use in designing supersonic laminar flow control wings. Results from this experiment will establish preliminary suction system design criteria enabling industry to better size the suction system and develop improved estimates of system weight, fuel volume loss due to wing ducting, turbocompressor power requirements, etc. so that benefits and penalties can be more accurately assessed.

  19. Numerical Analysis of Supersonic Film Cooling in Supersonic Flow in Hypersonic Inlet with Isolator

    Directory of Open Access Journals (Sweden)

    Silong Zhang

    2014-02-01

    Full Text Available Supersonic film cooling is an efficient method to cool the engine with extremely high heat load. In order to study supersonic film cooling in a real advanced engine, a two-dimensional model of the hypersonic inlet in a scramjet engine with supersonic film cooling in the isolator is built and validated through experimental data. The simulation results show that the cooling effect under different coolant injection angles does not show clear differences; a small injection angle can ensure both the cooling effect and good aerodynamic performances (e.g., flow coefficient of the hypersonic inlet. Under selected coolant injection angle and inlet Mach number, the cooling efficiency increases along with the injection Mach number of the coolant flow, only causing a little total pressure loss in the isolator. Along with the increase of the inlet Mach number of the hypersonic inlet, the cooling efficiency does not present a monotonic change because of the complex shock waves. However, the wall temperature shows a monotonic increase when the inlet Mach number increases. The mass flow rate of coolant flow should be increased to cool the engine more efficiently according to the mass flow rate of the main stream when the inlet Mach number increases.

  20. Simulation of underexpanded supersonic jet flows with chemical reactions

    Directory of Open Access Journals (Sweden)

    Fu Debin

    2014-06-01

    Full Text Available To achieve a detailed understanding of underexpanded supersonic jet structures influenced by afterburning and other flow conditions, the underexpanded turbulent supersonic jet with and without combustions are investigated by computational fluid dynamics (CFD method. A program based on a total variation diminishing (TVD methodology capable of predicting complex shocks is created to solve the axisymmetric expanded Navier–Stokes equations containing transport equations of species. The finite-rate ratio model is employed to handle species sources in chemical reactions. CFD solutions indicate that the structure of underexpanded jet is typically influenced by the pressure ratio and afterburning. The shock reflection distance and maximum value of Mach number in the first shock cell increase with pressure ratio. Chemical reactions for the rocket exhaust mostly exist in the mixing layer of supersonic jet flows. This tends to reduce the intensity of shocks existing in the jet, responding to the variation of thermal parameters.

  1. Simulation of underexpanded supersonic jet flows with chemical reactions

    Institute of Scientific and Technical Information of China (English)

    Fu Debin; Yu Yong; Niu Qinglin

    2014-01-01

    To achieve a detailed understanding of underexpanded supersonic jet structures influenced by afterburning and other flow conditions, the underexpanded turbulent supersonic jet with and without combustions are investigated by computational fluid dynamics (CFD) method. A program based on a total variation diminishing (TVD) methodology capable of predicting complex shocks is created to solve the axisymmetric expanded Navier-Stokes equations containing transport equations of species. The finite-rate ratio model is employed to handle species sources in chemical reactions. CFD solutions indicate that the structure of underexpanded jet is typically influenced by the pressure ratio and afterburning. The shock reflection distance and maximum value of Mach number in the first shock cell increase with pressure ratio. Chemical reactions for the rocket exhaust mostly exist in the mixing layer of supersonic jet flows. This tends to reduce the intensity of shocks existing in the jet, responding to the variation of thermal parameters.

  2. SIMULATION OF THE LASER DISCHARGE IN A SUPERSONIC GAS FLOW

    Directory of Open Access Journals (Sweden)

    Tropina, A. A.

    2013-06-01

    Full Text Available A heat model of the laser discharge in a supersonic turbulent gas flow has been developed. A numerical investigation of the error of the method of velocity measurements, which is based on the nitrogen molecules excitation, has been carried out. It is shown that fast gas heating by the discharge causes the velocity profiles deformation.

  3. A flamelet model for turbulent diffusion combustion in supersonic flow

    Institute of Scientific and Technical Information of China (English)

    LEE; ChunHian

    2010-01-01

    In order to develop a turbulent diffusion combustion model for supersonic flow, the physical argument of the extension of the flamelet model to supersonic flow was presented, and the flow field of a hydrogen/air diffusion combustion generated by axisymmetric supersonic jets was numerically simulated by employing the flamelet model. Using the experimental data, value of the model coefficient of scalar dissipation in the flamelet model was revised specifically for supersonic flow. The computational results of the modified flamelet model were compared with the experimental results, and it was indicated that the precision of the modified flamelet model was satisfying. Based on the numerical results and flamelet theory, the influence mechanisms of turbulence fluctuation on the average state equation and chemical reaction rate were studied for the first time. It was found that the fluctuation correlation of species mass fractions and temperature has little effect on the averaged gas state equation; the temperature fluctuation decreases the product of H2O, but its effect is small; the fluctuation of species mass fractions increases the product of H2O in the region close to oxidizer while decreases the product of H2O in other regions; the fluctuation correlation of species mass fractions and temperature largely decreases the product of H2O.

  4. Mixed exhaust flow supersonic jet engine and method

    Energy Technology Data Exchange (ETDEWEB)

    Klees, G.W.

    1993-06-08

    A method of operating a supersonic jet engine installation is described comprising (a) providing an engine having a variable area air inlet means and an outlet to discharge engine exhaust; (b) providing a secondary air passageway means; (c) receiving ambient air in the air inlet means and providing the ambient air as primary air to the engine inlet and secondary air to the secondary air passageway means; (d) providing a mixing section having an inlet portion and an exit portion, utilizing the mixing section in directing the exhaust from the engine to primary convergent/divergent exit passageway segments, where the exhaust is discharged at supersonic velocity as primary flow components, and directing secondary air flow from the secondary air passageway means to secondary exit passageway segments which are interspersed with the primary segments and from which the secondary air is discharged at subsonic velocity as secondary flow components; and (e) providing an exhaust section to receive the primary and secondary flow components in a mixing region and causing the primary and secondary flow components to mix to create a supersonic mixed flow, the exhaust section having a variable area final nozzle through which the mixed flow is discharged.

  5. Supersonic flow past a flat lattice of cylindrical rods

    Science.gov (United States)

    Guvernyuk, S. V.; Maksimov, F. A.

    2016-06-01

    Two-dimensional supersonic laminar ideal gas flows past a regular flat lattice of identical circular cylinders lying in a plane perpendicular to the free-stream velocity are numerically simulated. The flows are computed by applying a multiblock numerical technique with local boundary-fitted curvilinear grids that have finite regions overlapping the global rectangular grid covering the entire computational domain. Viscous boundary layers are resolved on the local grids by applying the Navier-Stokes equations, while the aerodynamic interference of shock wave structures occurring between the lattice elements is described by the Euler equations. In the overlapping grid regions, the functions are interpolated to the grid interfaces. The regimes of supersonic lattice flow are classified. The parameter ranges in which the steady flow around the lattice is not unique are detected, and the mechanisms of hysteresis phenomena are examined.

  6. The Two-Dimensional Supersonic Flow and Mixing with a Perpendicular Injection in a Scramjet Combustor

    Institute of Scientific and Technical Information of China (English)

    Mohammad Ali; S.Ahmed; A.K.M.Sadrul Islam

    2003-01-01

    A numerical investigation has been performed on supersonic mixing of hydrogen with air in a Scramjet(Supersonic Combustion Ramjet) combustor and its flame holding capability by solving Two-Dimensional full Navier-Stokes equations. The main flow is air entering through a finite width of inlet and gaseous hydrogen is injected perpendicularly from the side wall. An explicit Harten-Yee Non-MUSCL Modified-flux-type TVD scheme has been used to solve the system of equations, and a zero-equation algebraic turbulence model to calculate the eddy viscosity coefficient. In this study the enhancement of mixing and good flame holding capability of a supersonic combustor have been investigated by varying the distance of injector position from left boundary keeping constant the backward-facing step height and other calculation parameters. The results show that the configuration for small distance of injector position has high mixing efficiency but the upstream recirculation can not evolved properly which is an important factor for flame holding capability. On the other hand, the configuration for very long distance has lower mixing efficiency due to lower gradient of hydrogen mass concentration on the top of injector caused by the expansion of side jet in both upstream and downstream of injector. For moderate distance of injector position, large and elongated upstream recirculation can evolve which might be activated as a good flame holder.

  7. Experimental study of mixing enhancement using pylon in supersonic flow

    Science.gov (United States)

    Vishwakarma, Manmohan; Vaidyanathan, Aravind

    2016-01-01

    The Supersonic Combustion Ramjet (SCRAMJET) engine has been recognized as one of the most promising air breathing propulsion system for the supersonic/hypersonic flight mission requirements. Mixing and combustion of fuel inside scramjet engine is one of the major challenging tasks. In the current study the main focus has been to increase the penetration and mixing of the secondary jet inside the test chamber at supersonic speeds. In view of this, experiments are conducted to evaluate the effect of pylon on the mixing of secondary jet injection into supersonic mainstream flow at Mach 1.65. Two different pylons are investigated and the results are compared with those obtained by normal injection from a flat plate. The mixing studies are performed by varying the height of the pylon while keeping all other parameters the same. The study mainly focused on analyzing the area of spread and penetration depth achieved by different injection schemes based on the respective parameters. The measurements involved Mie scattering visualization and the flow features are analyzed using Schlieren images. The penetration height and spread area are the two parameters that are used for analyzing and comparing the performance of the pylons. It is observed that the secondary jet injection carried out from behind the big pylon resulted in maximum penetration and spread area of the jet as compared to the small pylon geometry. Moreover it is also evident that for obtaining maximum spreading and penetration of the jet, the same needs to be achieved at the injection location.

  8. Mass flow and its pulsation measurements in supersonic wing wake

    Science.gov (United States)

    Shmakov, A. S.; Shevchenko, A. M.; Yatskikh, A. A.; Yermolaev, Yu. G.

    2016-10-01

    The results of experimental study of the flow in the wing wake are presented. Experiments were carried out in supersonic wind tunnel T-325 of ITAM SB RAS. Rectangle half-wing with sharp edges with a chord length of 30 mm and semispan of 95 mm was used to generate vortex wake. Experimental data were obtained in the cross section located 6 chord length downstream of the trailing edge at Mach numbers of 2.5 and 4 and at wing angles of attack of 4 and 10 degrees. Constant temperature hot-wire anemometer was used to measure disturbances in supersonic flow. Hot-wire was made of a tungsten wire with a diameter of 10 μm and length of 1.5 mm. Shlieren flow visualization were performed. As a result, the position and size of the vortex core in the wake of a rectangular wing were determined. For the first time experimental data on the mass flow distribution and its pulsations in the supersonic longitudinal vortex were obtained.

  9. Dynamical separation of spherical bodies in supersonic flow

    OpenAIRE

    Laurence, Stuart; Parziale, N. J.; Deiterding, Ralf

    2012-01-01

    An experimental and computational investigation of the unsteady separation behaviour of two spheres in a highly supersonic flow is carried out. The spherical bodies, initially touching, are released with negligible relative velocity, an arrangement representing the idealized binary fragmentation of a meteoritic body in the atmosphere. In experiments performed in a Mach-4 Ludwieg tube, nylon spheres are initially suspended in the test section by weak threads and, following detachment of ...

  10. Study of the flow characteristics of supersonic coaxial jets

    Energy Technology Data Exchange (ETDEWEB)

    Lee, K.H. [Andong National University, Andong (Korea); Koo, B.S. [Andong National University Graudate School, Andong (Korea)

    2001-12-01

    Supersonic coaxial jets are investigated numerically by using the axisymmetric, Navier-Stokes equations which are solved using a fully implicit finite volume method. Three different kinds of coaxial nozzles are employed to understand the flow physics involved in the supersonic coaxial jets. Two convergent-divergent supersonic nozzles are designed to have the same Mach number 2.0, and used to compare the coaxial jet flows with those discharging from one constant-area nozzle. The impingement angle of the annular jets are varied. The primary pressure ratio is changed in the range from 2.0 to 10.0 and the assistant jet ratio from 1.0 to 3.0. The results obtained show that the fluctuations of the total pressure and Mach number along the jet axis are much higher in the constant-area nozzle than those in the convergent-divergent nozzles, and the constant-area nozzle lead to higher total pressure losses, compared with the convergent-divergent nozzles. The assistant jets from the annular nozzle affect the coaxial jet flows within the distance less than about ten times the nozzle throat diameter, but beyond it the coaxial jet is conical with self-similar velocity profiles. Increasing both the primary jet pressure ratio and the assistant jet pressure ratio produces a longer coaxial jet core. (author). 14 refs., 9 figs.

  11. Flow and acoustic features of a supersonic tapered nozzle

    Science.gov (United States)

    Gutmark, E.; Bowman, H. L.; Schadow, K. C.

    1992-05-01

    The acoustic and flow characteristics of a supersonic tapered jet were measured for free and shrouded flow configurations. Measurements were performed for a full range of pressure ratios including over- and underexpanded and design conditions. The supersonic tapered jet is issued from a converging-diverging nozzle with a 3∶1 rectangular slotted throat and a conical diverging section leading to a circular exit. The jet was compared to circular and rectangular supersonic jets operating at identical conditions. The distinct feature of the jet is the absence of screech tones in the entire range of operation. Its near-field pressure fluctuations have a wide band spectrum in the entire range of measurements, for Mach numbers of 1 to 2.5, for over- and underexpanded conditions. The free jet's spreading rate is nearly constant and similar to the rectangular jet, and in a shroud, the pressure drop it is inducing is linearly proportional to the primary jet Mach number. This behavior persisted in high adverse pressure gradients at overexpanded conditions, and with nozzle divergence angles of up to 35°, no inside flow separation was observed.

  12. Experiments on supersonic turbulent flow development in a square duct

    Science.gov (United States)

    Gessner, F. B.; Ferguson, S. D.; Lo, C. H.

    1986-01-01

    The nature of supersonic, turbulent, adiabatic-wall flow in a square duct is investigated experimentally over a development length of x/D between 0 and 20 for a uniform flow, Mach 3.9 condition at the duct inlet. Initial discussion centers on the duct configuration itself, which was designed specifically to minimize wave effects and nozzle-induced distortion in the flow. Total pressure contours and local skin friction coefficient distributions are presented which show that the flow develops in a manner similar to that observed for the incompressible case. In particular, undulations exist in total pressure contours within the cross plane and in transverse skin friction coefficient distributions, which are indicative of the presence of a well-defined secondary flow superimposed upon the primary flow. The results are analyzed to show that local law-of-the-wall behavior extends well into the corner region, which implies that wall functions conventionally applied in two-equation type turbulence models, when suitably defined for compressible flow, may also be applied to supersonic streamwise corner flows.

  13. Flow Control for Supersonic Inlet Applications

    Science.gov (United States)

    2014-06-10

    1221-1233, May 2013 3. Loth, E., Titchener, N., Babinsky, H., Povinelli , L., “Canonical NSBLI Flows Relevant to External Compression Inlets”, AIAA J...Tennessee, Jan. 9-12, 2012 7. Loth, E.L., Titchener, N., Babinsky, H., Povinelli , L.A., “A Canonical Normal SBLI Flow Relevant to External

  14. An analytical theory of heated duct flows in supersonic combustors

    Directory of Open Access Journals (Sweden)

    Chenxi Wu

    2014-01-01

    Full Text Available One-dimensional analytical theory is developed for supersonic duct flow with variation of cross section, wall friction, heat addition, and relations between the inlet and outlet flow parameters are obtained. By introducing a selfsimilar parameter, effects of heat releasing, wall friction, and change in cross section area on the flow can be normalized and a self-similar solution of the flow equations can be found. Based on the result of self-similar solution, the sufficient and necessary condition for the occurrence of thermal choking is derived. A relation of the maximum heat addition leading to thermal choking of the duct flow is derived as functions of area ratio, wall friction, and mass addition, which is an extension of the classic Rayleigh flow theory, where the effects of wall friction and mass addition are not considered. The present work is expected to provide fundamentals for developing an integral analytical theory for ramjets and scramjets.

  15. NUMERICAL ANALYSIS OF GASEOUS FLOW IN MICRO-CHANNELS

    Institute of Scientific and Technical Information of China (English)

    Xu Jie; Gu Chuangang; Wang Tong

    2004-01-01

    The algorithm of gaseous flow in bi-dimensional micro-channels is set up and the corresponding program based on micro-flow theory is presented. Gaseous flow in micro-channels is numerically analyzed and the pressure drop along the duct as well as the velocity profile in the micro-channels is obtained. The numerical results agreed well with the experimental results in the references. Moreover, the effects of Kn, (σv and Re on the velocity profiles are analyzed. It is found that for Kn>0.001, with increasing Kn number, the slip velocity on the wall boundary increases; the tangential momentum coefficient (σv affects the slip velocity greatly. The slip velocity increases with decreasing (σv In the slip flow regime and for low Re numbers, the slip velocity is little influenced by the Re number.

  16. Flow Patterns and Thermal Drag in Supersonic Duct Flow with Heating

    Institute of Scientific and Technical Information of China (English)

    Zeng-YuanGuo; Zhi-HongLiu

    1994-01-01

    The supersonic duct flow with fixed back pressure to stagnation pressure ratio Pb/P0 under heating is investigated analytically.A “Flow Pattern Diagram” Which consists of six pattern zones is developed.By this diagram the actual flow state in supersonic duct flow system can be determined conveniently when Pb/Po and heating intensity are knows.It is impossible for flow with heavy heating to become supersonic,even though the pressure ratio is much smaller than the critical pressure ratio,Based on the analogy between viscous effect and heating effect a thermal drag factor has een defined.which can predict the flow property variation due to heating and the relaive importance of viscous effect and heating effect.

  17. Unsteady Flow in a Supersonic Turbine with Variable Specific Heats

    Science.gov (United States)

    Dorney, Daniel J.; Griffin, Lisa W.; Huber, Frank; Sondak, Douglas L.; Turner, James (Technical Monitor)

    2001-01-01

    Modern high-work turbines can be compact, transonic, supersonic, counter-rotating, or use a dense drive gas. The vast majority of modern rocket turbine designs fall into these Categories. These turbines usually have large temperature variations across a given stage, and are characterized by large amounts of flow unsteadiness. The flow unsteadiness can have a major impact on the turbine performance and durability. For example, the Space Transportation Main Engine (STME) fuel turbine, a high work, transonic design, was found to have an unsteady inter-row shock which reduced efficiency by 2 points and increased dynamic loading by 24 percent. The Revolutionary Reusable Technology Turbopump (RRTT), which uses full flow oxygen for its drive gas, was found to shed vortices with such energy as to raise serious blade durability concerns. In both cases, the sources of the problems were uncovered (before turbopump testing) with the application of validated, unsteady computational fluid dynamics (CFD) to the designs. In the case of the RRTT and the Alternate Turbopump Development (ATD) turbines, the unsteady CFD codes have been used not just to identify problems, but to guide designs which mitigate problems due to unsteadiness. Using unsteady flow analyses as a part of the design process has led to turbine designs with higher performance (which affects temperature and mass flow rate) and fewer dynamics problems. One of the many assumptions made during the design and analysis of supersonic turbine stages is that the values of the specific heats are constant. In some analyses the value is based on an average of the expected upstream and downstream temperatures. In stages where the temperature can vary by 300 to 500 K, however, the assumption of constant fluid properties may lead to erroneous performance and durability predictions. In this study the suitability of assuming constant specific heats has been investigated by performing three-dimensional unsteady Navier

  18. Optical wavefront distortion due to supersonic flow fields

    Institute of Scientific and Technical Information of China (English)

    CHEN ZhiQiang; FU Song

    2009-01-01

    The optical wavefront distortion caused by a supersonic flow field around a half model of blunt nose cone was studied in a wind tunnel. A Shack-Hartmann wavefront sensor was used to measure the dis-totted optical wavefront. Interesting optical parameters including the peak variation (PV), root of mean square (RMS) and Strehl ratio were obtained under different test conditions during the experiment. During the establishing process of the flow field in the wind tunnel test section, the wavefront shape was unstable. However after the flow field reached the steady flow state, the wavefront shape kept sta-ble, and the relative error of wavefront aberration was found small. The Shack-Hartmann wavefront sensor developed was proved to be credible in measuring quantitatively the optical phase change of light traveling through the flow field around model window.

  19. Gaseous plume flows in space propulsion

    Institute of Scientific and Technical Information of China (English)

    Wang Limei; Cai Chunpei

    2013-01-01

    This paper presents a gaskinetic study on high-speed,highly rarefied jets expanding into a vacuum from a cluster of planar or annular exits.Based on the corresponding exact expressions for a planar or annular jet,it is convenient to derive the combined multiple jet flowfield solutions of density and velocity components.For the combined temperature and pressure solutions,extra attention is needed.Several direct simulation Monte Carlo simulation results are provided to validate these analytical solutions.The analytical and numerical solutions are essentially identical for these high Knudsen number jet flows.

  20. DIAMOND PORT JET INTERACTION WITH SUPERSONIC FLOW

    Institute of Scientific and Technical Information of China (English)

    2005-01-01

    Interaction flow field of the sonic air jet through diamond shaped orifices at different incidence angles (10 degrees, 27.5 degrees, 45 degrees and 90 degrees) and total pressures (0.10 MPa and 0. 46 MPa) with a Mach 5.0 freestream was studied experimentally. A 90 degrees circular injector was examined for comparison. Crosssection Mach number contours were acquired by a Pitot-cone five-hole pressure probe.The results indicate that the low Mach semicircular region close to the wall is the wake region. The boundary layer thinning is in the areas adjacent to the wake. For the detached case, the interaction shock extends further into the freestream, and the shock shape has more curvature, also the low-Mach upwash region is larger. The vortices of the plume and the height of the jet interaction shock increase with increasing incidence angle and jet pressure. 90 degrees diamond and circular injector have stronger plume vorticity, and for the circular injector low-Mach region is smaller than that for the diamond injector. Tapered ramp increases the plume vorticity, and the double ramp reduces the level of vorticity. The three-dimensional interaction shock shape was modeled from the surface shock shape, the center plane shock shape, and crosssectional shock shape. The shock total pressure was estimated with the normal component of the Mach number using normal shock theory. The shock induced total pressure losses decrease with decreasing jet incidence angle and injection pressure,where the largest losses are incurred by the 90 degrees, circular injector.

  1. Flow Simulation of Supersonic Inlet with Bypass Annular Duct

    Science.gov (United States)

    Kim, HyoungJin; Kumano, Takayasu; Liou, Meng-Sing; Povinelli, Louis A.; Conners, Timothy R.

    2011-01-01

    A relaxed isentropic compression supersonic inlet is a new concept that produces smaller cowl drag than a conventional inlet, but incurs lower total pressure recovery and increased flow distortion in the (radially) outer flowpath. A supersonic inlet comprising a bypass annulus to the relaxed isentropic compression inlet dumps out airflow of low quality through the bypass duct. A reliable computational fluid dynamics solution can provide considerable useful information to ascertain quantitatively relative merits of the concept, and further provide a basis for optimizing the design. For a fast and reliable performance evaluation of the inlet performance, an equivalent axisymmetric model whose area changes accounts for geometric and physical (blockage) effects resulting from the original complex three-dimensional configuration is proposed. In addition, full three-dimensional calculations are conducted for studying flow phenomena and verifying the validity of the equivalent model. The inlet-engine coupling is carried out by embedding numerical propulsion system simulation engine data into the flow solver for interactive boundary conditions at the engine fan face and exhaust plane. It was found that the blockage resulting from complex three-dimensional geometries in the bypass duct causes significant degradation of inlet performance by pushing the terminal normal shock upstream.

  2. Chirped Pulse Microwave Spectroscopy in Pulsed Uniform Supersonic Flows

    Science.gov (United States)

    Abeysekera, Chamara; Oldham, James; Prozument, Kirill; Joalland, Baptiste; Park, Barratt; Field, Robert W.; Sims, Ian; Suits, Arthur; Zack, Lindsay

    2014-06-01

    We present preliminary results describing the development of a new instrument that combines two powerful techniques: Chirped Pulse-Fourier Transform MicroWave (CP-FTMW) spectroscopy and pulsed uniform supersonic flows. It promises a nearly universal detection method that can deliver quantitative isomer, conformer, and vibrational level specific detection, characterization of unstable reaction products and intermediates and perform unique spectroscopic, kinetics and dynamics measurements. We have constructed a new high-power K_a-band, 26-40 GHz, chirped pulse spectrometer with sub-MHz resolution, analogous to the revolutionary CP-FTMW spectroscopic technique developed in the Pate group at University of Virginia. In order to study smaller molecules, the E-band, 60-90 GHz, CP capability was added to our spectrometer. A novel strategy for generating uniform supersonic flow through a Laval nozzle is introduced. High throughput pulsed piezo-valve is used to produce cold (30 K) uniform flow with large volumes of 150 cm^3 and densities of 1014 molecules/cm3 with modest pumping facilities. The uniform flow conditions for a variety of noble gases extend as far as 20 cm from the Laval nozzle and a single compound turbo-molecular pump maintains the operating pressure. Two competing design considerations are critical to the performance of the system: a low temperature flow is needed to maximize the population difference between rotational levels, and high gas number densities are needed to ensure rapid cooling to achieve the uniform flow conditions. At the same time, collision times shorter than the chirp duration will give inaccurate intensities and reduced signal levels due to collisional dephasing of free induction decay. Details of the instrument and future directions and challenges will be discussed.

  3. Constant-temperature hot-wire anemometer practice in supersonic flows. II - The inclined wire

    Science.gov (United States)

    Smits, A. J.; Muck, K. C.

    1983-01-01

    The performance of a constant-temperature inclined hot-wire in a supersonic flow is critically examined. It is shown that calibration techniques applicable to subsonic flow, such as the cosine cooling law cannot be used when the flow is supersonic. Calibration and measurement procedures appropriate to supersonic flow are suggested, together with the possible limits on their validity. Experimental results for different wires indicate that the sensitivities do not seem to depend on flow direction according to any simple correlation. When the sensitivity exhibits a strong dependence on flow direction, the wire should be discarded to avoid errors due to nonlinear effects.

  4. Flight tests of a supersonic natural laminar flow airfoil

    Science.gov (United States)

    Frederick, M. A.; Banks, D. W.; Garzon, G. A.; Matisheck, J. R.

    2015-06-01

    A flight test campaign of a supersonic natural laminar flow airfoil has been recently completed. The test surface was an 80 inch (203 cm) chord and 40 inch (102 cm) span article mounted on the centerline store location of an F-15B airplane. The test article was designed with a leading edge sweep of effectively 0° to minimize boundary layer crossflow. The test article surface was coated with an insulating material to avoid significant heat transfer to and from the test article structure to maintain a quasi-adiabatic wall. An aircraft-mounted infrared camera system was used to determine boundary layer transition and the extent of laminar flow. The tests were flown up to Mach 2.0 and chord Reynolds numbers in excess of 30 million. The objectives of the tests were to determine the extent of laminar flow at high Reynolds numbers and to determine the sensitivity of the flow to disturbances. Both discrete (trip dots) and 2D disturbances (forward-facing steps) were tested. A series of oblique shocks, of yet unknown origin, appeared on the surface, which generated sufficient crossflow to affect transition. Despite the unwanted crossflow, the airfoil performed well. The results indicate that the sensitivity of the flow to the disturbances, which can translate into manufacturing tolerances, was similar to that of subsonic natural laminar flow wings.

  5. Thermonuclear dynamo inside ultracentrifuge with supersonic plasma flow stabilization

    Energy Technology Data Exchange (ETDEWEB)

    Winterberg, F. [University of Nevada, Reno, Reno, Nevada (United States)

    2016-01-15

    Einstein's general theory of relativity implies the existence of virtual negative masses in the rotational reference frame of an ultracentrifuge with the negative mass density of the same order of magnitude as the positive mass density of a neutron star. In an ultracentrifuge, the repulsive gravitational field of this negative mass can simulate the attractive positive mass of a mini-neutron star, and for this reason can radially confine a dense thermonuclear plasma placed inside the centrifuge, very much as the positive mass of a star confines its plasma by its own attractive gravitational field. If the centrifuge is placed in an externally magnetic field to act as the seed field of a magnetohydrodynamic generator, the configuration resembles a magnetar driven by the release of energy through nuclear fusion, accelerating the plasma to supersonic velocities, with the magnetic field produced by the thermomagnetic Nernst effect insulating the hot plasma from the cold wall of the centrifuge. Because of the supersonic flow and the high plasma density the configuration is stable.

  6. Turbulence characteristics in a supersonic cascade wake flow

    Energy Technology Data Exchange (ETDEWEB)

    Andrew, P.L.; Ng, W.F. (Virginia Polytechnic Inst. and State Univ., Blacksburg, VA (United States))

    1994-10-01

    The turbulent character of the supersonic wake of a linear cascade of fan airfoils has been studied using a two-component laser-doppler anemometer. The cascade was tested in the Virginia Polytechnic Institute and State University intermittent wind tunnel facility, where the Mach and Reynolds numbers were 2.36 and 4.8 [times] 10[sup 6], respectively. In addition to mean flow measurements, Reynolds normal and shear stresses were measured as functions of cascade incidence angle and streamwise locations spanning the near-wake and the far-wake. The extremities of profiles of both the mean and turbulent wake properties were found to be strongly influenced by upstream shock-boundary-layer interactions, the strength of which varied with cascade incidence. In contrast, the peak levels of turbulence properties within the shear layer were found to be largely independent of incidence, and could be characterized in terms of the streamwise position only. The velocity defect turbulence level was found to be 23%, and the generally accepted value of the turbulence structural coefficient of 0.30 was found to be valid for this flow. The degree of similarity of the mean flow wake profiles was established, and those profiles demonstrating the most similarity were found to approach a state of equilibrium between the mean and turbulent properties. In general, this wake flow may be described as a classical free shear flow, upon which the influence of upstream shock-boundary-layer interactions has been superimposed.

  7. Unsteady transverse injection of kerosene into a supersonic flow

    Institute of Scientific and Technical Information of China (English)

    2000-01-01

    A shadowgraph and a new fuel injection system were used to study kerosene transversely injected into a supersonic flow. High pressure and velocity of injection can be attained. The pressure time histories were detected in oil-line and the shadowgraphs of the flow field were obtained at different time-delays. The inflow stagnation pressure was varied to change the local flow speed in test section. The results indicate that kerosene jet exhibits deep penetration and four regimes appear clearly during the fuel jet atomization in a high-speed flow. The jet disintegration is caused by surface waves propagating along the jet surface, and the breakup point is located at the wave trough. The surface waves are dominantly generated by aerodynamic force. The jet shock is close to windward surface of the jet. The shock reflects on and transmits in duct boundary layers. In the case of unsteady injection, the shock structure is very complicated and different from that of hydrogen injection. The results of kerosene injected into a quiescent gas and a subsonic flow are also provided for comparison.

  8. Studies of the unsteady supersonic base flows around three afterbodies

    Institute of Scientific and Technical Information of China (English)

    Zhixiang Xiao; Song Fu

    2009-01-01

    Unsteady supersonic base flows around three afterbodies, cylindrical (Cy), boattailed (BT) and three-step (MS), are investigated in this paper. Reynolds-averaged Navier-Stokes (RANS) and two RANS/LES (large-eddy simulation) hybrid methods, detached eddy simulation (DES) and delayed-DES (DDES), are used to predict the base flow characteristics around the baseline Cy afterbody. All the RANS and hybrid methods are based on the two-equation SST (shear-stress transport) model with compressible corrections (CC). According to the comparison of measurements, both DES and DDES can produce more satisfactory results than RANS. RANS can only present the "stable" flow patterns, while the hybrid methods can demonstrate unsteady flow structures. DDES and DES results are little different from one another although the latter exhibits better agreement with the experiment. DES is taken to investigate the 5 BT and three-step afterbodies. The mean flow data and the instantaneous turbulent coherent structures are compared against available measurements.

  9. Influences of friction drag on spontaneous condensation in water vapor supersonic flows

    Institute of Scientific and Technical Information of China (English)

    2009-01-01

    A mathematical model was developed to investigate the water vapor spontaneous condensation under supersonic flow conditions. A numerical simulation was performed for the water vapor condensable supersonic flows through Laval nozzles under different flow friction conditions. The comparison between numerical and experimental results shows that the model is accurate enough to investigate the supersonic spontaneous condensation flow of water vapor inside Laval nozzles. The influences of flow friction drag on supersonic spontaneous condensation flow of water vapor inside Laval nozzles were investigated. It was found that the flow friction has a direct effect on the spontaneous condensation process and therefore it is important for an accurate friction prediction in designing this kind of Laval nozzles.

  10. Influences of friction drag on spontaneous condensation in water vapor supersonic flows

    Institute of Scientific and Technical Information of China (English)

    JIANG WenMing; LIU ZhongLiang; LIU HengWei; PANG HuiZhong; BAO LingLing

    2009-01-01

    A mathematical model was developed to investigate the water vapor spontaneous condensation under supersonic flow conditions. A numerical simulation was performed for the water vapor condensable supersonic flows through Laval nozzles under different flow friction conditions. The comparison be-tween numerical and experimental results shows that the model is accurate enough to investigate the supersonic spontaneous condensation flow of water vapor inside Laval nozzles. The influences of flow friction drag on supersonic spontaneous condensation flow of water vapor inside Laval nozzles were investigated, It was found that the flow friction has a direct effect on the spontaneous condensation process and therefore it is important for an accurate friction prediction in designing this kind of Laval nozzles.

  11. Gaskinetic Modeling on Dilute Gaseous Plume Impingement Flows

    Directory of Open Access Journals (Sweden)

    Chunpei Cai

    2016-12-01

    Full Text Available This paper briefly reviews recent work on gaseous plume impingement flows. As the major part of this paper, also included are new comprehensive studies on high-speed, collisionless, gaseous, circular jet impinging on a three-dimensional, inclined, diffuse or specular flat plate. Gaskinetic theories are adopted to study the problems, and several crucial geometry-location and velocity-direction relations are used. The final complete results include impingement surface properties such as pressure, shear stress, and heat flux. From these surface properties, averaged coefficients of pressure, friction, heat flux, moment over the entire flat plate, and the distance from the moment center to the flat plate center are obtained. The final results include accurate integrations involving the geometry and specific speed ratios, inclination angle, and the temperature ratio. Several numerical simulations with the direct simulation Monte Carlo method validate these analytical results, and the results are essentially identical. The gaskinetic method and processes are heuristic and can be used to investigate other external high Knudsen (Kn number impingement flow problems, including the flow field and surface properties for a high Knudsen number jet from an exit and flat plate of arbitrary shapes. The results are expected to find many engineering applications, especially in aerospace and space engineering.

  12. Quasi-DC electrical discharge characterization in a supersonic flow

    Science.gov (United States)

    Houpt, Alec; Hedlund, Brock; Leonov, Sergey; Ombrello, Timothy; Carter, Campbell

    2017-04-01

    A Quasi-DC (Q-DC) electrical discharge generates a highly transient filamentary plasma in high-speed airflow. Major specific properties of this type of discharge are realized due to a strong coupling of the plasma to the moving gas. The plasma, supplied by a DC voltage waveform, demonstrates a pulsed-periodic pattern of dynamics significantly affecting the flow structure. In this study, the dynamics and plasma parameters of the Q-DC discharge are analyzed in the Supersonic Test Rig (SBR-50) at the University of Notre Dame at Mach number M = 2, stagnation pressure P 0 = (0.9-2.6) × 105 Pa, stagnation temperature T 0 = 300 K, unit Reynolds number ReL = 7-25 × 106 m-1, and plasma power W pl = 3-21 kW. The plasma parameters are measured with current-voltage probes and optical emission spectroscopy. An unsteady pattern of interaction is depicted by high-speed image capturing. The result of the plasma-flow interaction is characterized by means of pressure measurements and schlieren visualization. It is considered that the Q-DC discharge may be employed for active control of duct-driven flows, cavity-based flow, and for effective control of shock wave-boundary layer interaction.

  13. Unsteady transverse injection of kerosene into a supersonic flow

    Institute of Scientific and Technical Information of China (English)

    徐胜利; R.D.Archer; B.E.Milton; 岳朋涛

    2000-01-01

    A shadowgraph and a new fuel injection system were used to study kerosene transversely injected into a supersonic flow. High pressure and velocity of injection can be attained. The pressure time histories were detected in oil-line and the shadowgraphs of the flow field were obtained at different time-delays. The inflow stagnation pressure was varied to change the local flow speed in test section. The results indicate that kerosene jet exhibits deep penetration and four regimes appear clearly during the fuel jet atomization in a high-speed flow. The jet disintegration is caused by surface waves propagating along the jet surface, and the breakup point is located at the wave trough. The surface waves are dominantly generated by aerodynamic force. The jet shock is close to windward surface of the jet. The shock reflects on and transmits in duct boundary layers. In the case of unsteady injection, the shock structure is very complicated and different from that of hydrogen injection. The results of kerosene inj

  14. Plasma-enhanced mixing and flameholding in supersonic flow

    Science.gov (United States)

    Firsov, Alexander; Savelkin, Konstantin V.; Yarantsev, Dmitry A.; Leonov, Sergey B.

    2015-01-01

    The results of experimental study of plasma-based mixing, ignition and flameholding in a supersonic model combustor are presented in the paper. The model combustor has a length of 600 mm and cross section of 72 mm width and 60 mm height. The fuel is directly injected into supersonic airflow (Mach number M=2, static pressure Pst=160–250 Torr) through wall orifices. Two series of tests are focused on flameholding and mixing correspondingly. In the first series, the near-surface quasi-DC electrical discharge is generated by flush-mounted electrodes at electrical power deposition of Wpl=3–24 kW. The scope includes parametric study of ignition and flame front dynamics, and comparison of three schemes of plasma generation: the first and the second layouts examine the location of plasma generators upstream and downstream from the fuel injectors. The third pattern follows a novel approach of combined mixing/ignition technique, where the electrical discharge distributes along the fuel jet. The last pattern demonstrates a significant advantage in terms of flameholding limit. In the second series of tests, a long discharge of submicrosecond duration is generated across the flow and along the fuel jet. A gasdynamic instability of thermal cavity developed after a deposition of high-power density in a thin plasma filament promotes the air–fuel mixing. The technique studied in this work has weighty potential for high-speed combustion applications, including cold start/restart of scramjet engines and support of transition regime in dual-mode scramjet and at off-design operation. PMID:26170434

  15. Effect of Nonequilibrium Homogenous COndensation on Flow Fields in a Supersonic Nozzle

    Institute of Scientific and Technical Information of China (English)

    ToshiakiSetoguchi; ShenYu; 等

    1997-01-01

    When condensation occurs in a supersonic flow field,the flow is affected by the latent heat released.In the present study,a condensing flow was produced by an expansion of moist air in a supersonic circular nozzle,and,by inserting a wedge-type shock generator placed in the supersonic part of the nozzle,the experimental investigations were carried out to clarify the effect of condensation on the normal shock wave and the boundary layer.As a result,the position of the shock wave relative to the condensation zone was discussed,together with the effect of condensation on pressure fluctuations.Furthermore,a compressible viscous two-phase flow of moist air in a supersonic half nozzle was calculated to investigate the effect of condensation on boundary layer.

  16. Effect of swirling device on flow behavior in a supersonic separator for natural gas dehydration

    DEFF Research Database (Denmark)

    Wen, Chuang; Li, Anqi; Walther, Jens Honore;

    2016-01-01

    The supersonic separator is a revolutionary device to remove the condensable components from gas mixtures. One of the key issues for this novel technology is the complex supersonic swirling flow that is not well understood. A swirling device composed of an ellipsoid and several helical blades is ...... the separation performance. When the swirling flow passes through the annular nozzle, it will damage the expansion characteristics of the annular nozzle. The blade angles and numbers are both optimized by evaluating the swirling and expansion effects for the supersonic separation....

  17. Fission fragments transport by gaseous flow with aerosols

    CERN Document Server

    Gangrskij, Y P; Zhemenik, V I; Myshinskij, G V; Penionzhkevich, Yu E; Selesh, O

    2002-01-01

    Paper describes a pilot facility for fission fragment transport by gaseous flow with aerosols. This facility designed for fragment transport consists of a reaction chamber with irradiated target, receipt chamber to collect fragments, aerosol generator, roughing pump to pump put gas and a capillary connecting these units of facility. Paper presents the results of facility testing with fragments of sup 2 sup 3 sup 8 U photofission by microtron Bremsstrahlung. The obtained parameters of facility (up to 70% efficiency of transport, up to 0.1 s time of transport at 1 m distance) enable to use it efficiently in experiments dealing with heavy nuclei fission and with investigation in properties of fission fragments

  18. Hypersonic Engine Leading Edge Experiments in a High Heat Flux, Supersonic Flow Environment

    Science.gov (United States)

    Gladden, Herbert J.; Melis, Matthew E.

    1994-01-01

    A major concern in advancing the state-of-the-art technologies for hypersonic vehicles is the development of an aeropropulsion system capable of withstanding the sustained high thermal loads expected during hypersonic flight. Three aerothermal load related concerns are the boundary layer transition from laminar to turbulent flow, articulating panel seals in high temperature environments, and strut (or cowl) leading edges with shock-on-shock interactions. A multidisciplinary approach is required to address these technical concerns. A hydrogen/oxygen rocket engine heat source has been developed at the NASA Lewis Research Center as one element in a series of facilities at national laboratories designed to experimentally evaluate the heat transfer and structural response of the strut (or cowl) leading edge. A recent experimental program conducted in this facility is discussed and related to cooling technology capability. The specific objective of the experiment discussed is to evaluate the erosion and oxidation characteristics of a coating on a cowl leading edge (or strut leading edge) in a supersonic, high heat flux environment. Heat transfer analyses of a similar leading edge concept cooled with gaseous hydrogen is included to demonstrate the complexity of the problem resulting from plastic deformation of the structures. Macro-photographic data from a coated leading edge model show progressive degradation over several thermal cycles at aerothermal conditions representative of high Mach number flight.

  19. Unsteady flow in a supersonic cascade with strong in-passage shocks

    Science.gov (United States)

    Goldstein, M. E.; Braun, W.; Adamczyk, J. J.

    1977-01-01

    Linearized theory is used to study the unsteady flow in a supersonic cascade with in-passage shock waves. We use the Wiener-Hopf technique to obtain a closed-form analytical solution for the supersonic region. To obtain a solution for the rotational flow in the subsonic region we must solve an infinite set of linear algebraic equations. The analysis shows that it is possible to correlate quantitatively the oscillatory shock motion with the Kutta condition at the trailing edges of the blades. This feature allows us to account for the effect of shock motion on the stability of the cascade. Unlike the theory for a completely supersonic flow, the present study predicts the occurrence of supersonic bending flutter. It therefore provides a possible explanation for the bending flutter that has recently been detected in aircraft-engine compressors at higher blade loadings.

  20. The flow feature of transverse hydrogen jet in presence of micro air jets in supersonic flow

    Science.gov (United States)

    Barzegar Gerdroodbary, M.; Amini, Younes; Ganji, D. D.; Takam, ​M. Rahimi

    2017-03-01

    Scramjet is found to be the efficient method for the space shuttle. In this paper, numerical simulation is performed to investigate the fundamental flow physics of the interaction between an array of fuel jets and multi air jets in a supersonic transverse flow. Hydrogen as a fuel is released with a global equivalence ratio of 0.5 in presence of micro air jets on a flat plate into a Mach 4 crossflow. The fuel and air are injected through streamwise-aligned flush circular portholes. The hydrogen is injected through 4 holes with 7dj space when the air is injected in the interval of the hydrogen jets. The numerical simulation is performed by using the Reynolds-averaged Navier-Stokes equations with Menter's Shear Stress Transport (SST) turbulence model. Both the number of air jets and jet-to-freestream total pressure ratio are varied in a parametric study. The interaction of the fuel and air jet in the supersonic flow present extremely complex feature of fuel and air jet. The results present various flow features depending upon the number and mass flow rate of micro air jets. These flow features were found to have significant effects on the penetration of hydrogen jets. A variation of the number of air jets, along with the jet-to-freestream total pressure ratio, induced a variety of flow structure in the downstream of the fuel jets.

  1. Numerical Simulation of the Supersonic Flows in the Second Throat Ejector —Diffuser Systems

    Institute of Scientific and Technical Information of China (English)

    HeuydongKim; ToshiakiSetoguchi; 等

    1999-01-01

    The supersonic ejector-diffuser system with a second throat was simulated using CFD.A fully implicity finite volume scheme was applied to solve the axisymmetric Navier-Stokes equations and a standard k-ε turbulence model was used to close the governing equations,The flow field in the supersonic ejectordiffuser system was investigated by changing the ejector throat area ratio and the secondary mass flow ratio at a fixed operating pressure ratio of 10. A convergent-divergent nozzle with a design Mach number of 2.11 was selected to give the supersonic operation of the ejector -diffuser system.For the constant area mixing tube the secondary mass flow seemed not to singnificantly change the flow field in the ejector-diffuser systems.It was however,found that the flow in the ejector-diffuser systems having the second throat is strongly dependent on the secondary mass flow.

  2. Shock Train and Pseudo-shock Phenomena in Supersonic Internal Flows

    Institute of Scientific and Technical Information of China (English)

    Kazuyasu Matsuo

    2003-01-01

    When a normal shock wave interacts with a boundary layer along a wall surface in supersonic internal flows and the shock is strong enough to separate the boundary layer, the shock is bifurcated and a series of shocks called "shock train" is formed. The flow is decelerated from supersonic to subsonic through the whole interaction region that is referred to as "pseudo-shock". In the present paper some characteristics of the shock train and pseudo-shock and some examples of the pseudo-shocks in some flow devices are described.

  3. Observation of Single-Mode, Kelvin-Helmholtz Instability in a Supersonic Flow.

    Science.gov (United States)

    Wan, W C; Malamud, G; Shimony, A; Di Stefano, C A; Trantham, M R; Klein, S R; Shvarts, D; Kuranz, C C; Drake, R P

    2015-10-02

    We report the first observation, in a supersonic flow, of the evolution of the Kelvin-Helmholtz instability from a single-mode initial condition. To obtain these data, we used a novel experimental system to produce a steady shock wave of unprecedented duration in a laser-driven experiment. The shocked, flowing material creates a shear layer between two plasmas at high energy density. We measured the resulting interface structure using radiography. Hydrodynamic simulations reproduce the large-scale structures very well and the medium-scale structures fairly well, and imply that we observed the expected reduction in growth rate for supersonic shear flow.

  4. Quantitative planar Raman imaging through a spectrograph: visualisation of a supersonic wedge flow

    NARCIS (Netherlands)

    Tolboom, R.A.L.; Dam, N.J.; Meulen, J.J. ter; Bakker, P.G.

    2005-01-01

    Planar Raman imaging through a spectrograph is demonstrated as a diagnostic tool for quantitative flow visualisation of internal supersonic wedge flow. A dedicated Bayesian deconvolution filter is used to remove the spectral structure that is introduced by the spectrograph. The 2D density field is d

  5. The three-dimensional flow organization past a micro-ramp in a supersonic boundary layer

    NARCIS (Netherlands)

    Sun, Z.; Schrijer, F.F.J.; Scarano, F.; Van Oudheusden, B.W.

    2012-01-01

    The three-dimensional instantaneous flow organization in the near wake of a micro-ramp interacting with a Mach 2.0 supersonic turbulent boundary layer is studied using tomographic particle image velocimetry. The mean flow reveals a wake with approximately circular cross section dominated by a pair o

  6. Shock Waves Oscillations in the Interaction of Supersonic Flows with the Head of the Aircraft

    Science.gov (United States)

    Bulat, Pavel V.; Volkov, Konstantin N.

    2016-01-01

    In this article we reviewed the shock wave oscillation that occurs when supersonic flows interact with conic, blunt or flat nose of aircraft, taking into account the aerospike attached to it. The main attention was paid to the problem of numerical modeling of such oscillation, flow regime classification, and cases where aerospike attachment can…

  7. Study of density field measurement based on NPLS technique in supersonic flow

    Institute of Scientific and Technical Information of China (English)

    2009-01-01

    Due to the influence of shock wave and turbulence, supersonic density field exhibits strongly inhomogeneous and unsteady characteristics. Applying traditional density field measurement techniques to supersonic flows yields three problems: low spatiotemporal resolution, limitation of measuring 3D density field, and low signal to noise ratio (SNR). A new method based on Nano-based Planar Laser Scattering (NPLS) technique is proposed in this paper to measure supersonic density field. This method measures planar transient density field in 3D supersonic flow by calibrating the relationship between density and concentration of tracer particles, which would display the density fluctuation due to the influence of shock waves and vortexes. The application of this new method to density field measurement of supersonic optical bow cap is introduced in this paper, and the results reveal shock wave, turbulent boundary layer in the flow with the spatial resolution of 93.2 μm/pixel. By analyzing the results at interval of 5 μs, temporal evolution of density field can be observed.

  8. Study of density field measurement based on NPLS technique in supersonic flow

    Institute of Scientific and Technical Information of China (English)

    TIAN LiFeng; YI ShiHe; ZHAO YuXin; HE Lin; CHENG ZhongYu

    2009-01-01

    Due to the influence of shock wave and turbulence,supersonic density field exhibits strongly inho-mogeneous and unsteady characteristics.Applying traditional density field measurement techniques to supersonic flows yields three problems: low spatiotemporal resolution,limitation of measuring 3D density field,and low signal to noise ratio (SNR).A new method based on Nano-based Planar Laser Scattering (NPLS) technique is proposed in this paper to measure supersonic density field.This method measures planar transient density field in 3D supersonic flow by calibrating the relationship between density and concentration of tracer particles,which would display the density fluctuation due to the influence of shock waves and vortexes.The application of this new method to density field measurement of supersonic optical bow cap is introduced in this paper,and the results reveal shock wave,turbulent boundary layer in the flow with the spatial resolution of 93.2 pm/pixel.By analyzing the results at interval of 5 μs,temporal evolution of density field can be observed.

  9. Analysis of supersonic stall bending flutter in axial-flow compressor by actuator disk theory

    Science.gov (United States)

    Adamczyk, J. J.

    1978-01-01

    An analytical model was developed for predicting the onset of supersonic stall bending flutter in axial-flow compressors. The analysis is based on two-dimensional, compressible, unsteady actuator disk theory. It is applied to a rotor blade row by considering a cascade of airfoils. The effects of shock waves and flow separation are included in the model. Calculations show that the model predicts the onset, in an unshrouded rotor, of a bending flutter mode that exhibits many of the characteristics of supersonic stall bending flutter. The validity of the analysis for predicting this flutter mode is demonstrated.

  10. Thermocapillary flow and gaseous convection in microgravity: Results from GAS payload G-0518

    Science.gov (United States)

    Thomas, S.

    1986-01-01

    Thermocapillary flow and gaseous convection in microgravity were investigated in GAS payload G-0518 during Space Shuttle Mission 41-D. A cylinder of paraffin was supported and heated differentially from its ends to induce a melt from solid to liquid and drive thermocapillary flow in the resulting liquid phase. Laminar thermocapillary flow was observed in the liquid paraffin and found to show a transition to time-dependent oscillatory motion at a Marangoni number of about Ma = 34000 with a period of approximately T = 8 seconds. In addition, free convection in a gas in microgravity was observed for the first time. The gaseous convection was caused by the thermal and/or velocity boundary layers present at the heater-liquid interface. Oscillation occurred in the gaseous convection simultaneously with those in the liquid, implying the two are strongly coupled. The gaseous convection may be driven by coupled thermocapillary flow/thermal expansion convection or microgravity bouyancy convection.

  11. EOIL power scaling in a 1-5 kW supersonic discharge-flow reactor

    Science.gov (United States)

    Davis, Steven J.; Lee, Seonkyung; Oakes, David B.; Haney, Julie; Magill, John C.; Paulsen, Dwane A.; Cataldi, Paul; Galbally-Kinney, Kristin L.; Vu, Danthu; Polex, Jan; Kessler, William J.; Rawlins, Wilson T.

    2008-02-01

    Scaling of EOIL systems to higher powers requires extension of electric discharge powers into the kW range and beyond with high efficiency and singlet oxygen yield. We have previously demonstrated a high-power microwave discharge approach capable of generating singlet oxygen yields of ~25% at ~50 torr pressure and 1 kW power. This paper describes the implementation of this method in a supersonic flow reactor designed for systematic investigations of the scaling of gain and lasing with power and flow conditions. The 2450 MHz microwave discharge, 1 to 5 kW, is confined near the flow axis by a swirl flow. The discharge effluent, containing active species including O II(a1Δ g, b1Σ g +), O( 3P), and O 3, passes through a 2-D flow duct equipped with a supersonic nozzle and cavity. I2 is injected upstream of the supersonic nozzle. The apparatus is water-cooled, and is modular to permit a variety of inlet, nozzle, and optical configurations. A comprehensive suite of optical emission and absorption diagnostics is used to monitor the absolute concentrations of O II(a), O II(b), O( 3P), O 3, I II, I(2P 3/2), I(2P 1/2), small-signal gain, and temperature in both the subsonic and supersonic flow streams. We discuss initial measurements of singlet oxygen and I* excitation kinetics at 1 kW power.

  12. Numerical investigation and optimization on mixing enhancement factors in supersonic jet-to-crossflow flow fields

    Science.gov (United States)

    Yan, Li; Huang, Wei; Li, Hao; Zhang, Tian-tian

    2016-10-01

    Sufficient mixing between the supersonic airstream and the injectant is critical for the design of scramjet engines. The information in the two-dimensional supersonic jet-to-crossflow flow field has been explored numerically and theoretically, and the numerical approach has been validated against the available experimental data in the open literature. The obtained results show that the extreme difference analysis approach can obtain deeper information than the variance analysis method, and the optimal strategy can be generated by the extreme difference analysis approach. The jet-to-crossflow pressure ratio is the most important influencing factor for the supersonic jet-to-crossflow flow field, following is the injection angle, and all the design variables have no remarkable impact on the separation length and the height of Mach disk in the range considered in the current study.

  13. Trajectory Analysis of Fuel Injection into Supersonic Cross Flow Based on Schlieren Method

    Institute of Scientific and Technical Information of China (English)

    YANG Hui; LI Feng; SUN Baigang

    2012-01-01

    Trajectory analysis of fuel injection into supersonic cross flow is studied in this paper.A directly-connected wind tunnel is constructed to provide stable supersonic freestream.Based on the test rig,the schlieren system is established to reveal the fuel injection process visually.Subsequently,the method of quantitative schlieren is adopted to obtain data of both fuel/air interface and bow shock with the aid of Photoshop and Origin.Finally,the mechanism based on two influential factors of fuel injection angle and fuel injection driven pressure,is researched by vector analysis.A dimensionless model is deduced and analyzed.The curve fitting result is achieved.The relationship between the data and the two influential factors is established.The results provide not only the quantitative characteristics of the fuel injection in supersonic cross flow but also the valuable reference for the future computational simulation.

  14. Turbulence coefficients and stability studies for the coaxial flow or dissimiliar fluids. [gaseous core nuclear reactors

    Science.gov (United States)

    Weinstein, H.; Lavan, Z.

    1975-01-01

    Analytical investigations of fluid dynamics problems of relevance to the gaseous core nuclear reactor program are presented. The vortex type flow which appears in the nuclear light bulb concept is analyzed along with the fluid flow in the fuel inlet region for the coaxial flow gaseous core nuclear reactor concept. The development of numerical methods for the solution of the Navier-Stokes equations for appropriate geometries is extended to the case of rotating flows and almost completes the gas core program requirements in this area. The investigations demonstrate that the conceptual design of the coaxial flow reactor needs further development.

  15. Characteristics of pulsed plasma synthetic jet and its control effect on supersonic flow

    Institute of Scientific and Technical Information of China (English)

    Jin Di; Cui Wei; Li Yinghong; Li Fanyu; Jia Min; Sun Quan; Zhang Bailing

    2015-01-01

    The plasma synthetic jet is a novel flow control approach which is currently being stud-ied. In this paper its characteristic and control effect on supersonic flow is investigated both exper-imentally and numerically. In the experiment, the formation of plasma synthetic jet and its propagation velocity in quiescent air are recorded and calculated with time resolved schlieren method. The jet velocity is up to 100 m/s and no remarkable difference has been found after chang-ing discharge parameters. When applied in Mach 2 supersonic flow, an obvious shockwave can be observed. In the modeling of electrical heating, the arc domain is not defined as an initial condition with fixed temperature or pressure, but a source term with time-varying input power density, which is expected to better describe the influence of heating process. Velocity variation with different heat-ing efficiencies is presented and discussed and a peak velocity of 850 m/s is achieved in still air with heating power density of 5.0 · 1012 W/m3. For more details on the interaction between plasma syn-thetic jet and supersonic flow, the plasma synthetic jet induced shockwave and the disturbances in the boundary layer are numerically researched. All the results have demonstrated the control authority of plasma synthetic jet onto supersonic flow.

  16. Characteristics of pulsed plasma synthetic jet and its control effect on supersonic flow

    Directory of Open Access Journals (Sweden)

    Jin Di

    2015-02-01

    Full Text Available The plasma synthetic jet is a novel flow control approach which is currently being studied. In this paper its characteristic and control effect on supersonic flow is investigated both experimentally and numerically. In the experiment, the formation of plasma synthetic jet and its propagation velocity in quiescent air are recorded and calculated with time resolved schlieren method. The jet velocity is up to 100 m/s and no remarkable difference has been found after changing discharge parameters. When applied in Mach 2 supersonic flow, an obvious shockwave can be observed. In the modeling of electrical heating, the arc domain is not defined as an initial condition with fixed temperature or pressure, but a source term with time-varying input power density, which is expected to better describe the influence of heating process. Velocity variation with different heating efficiencies is presented and discussed and a peak velocity of 850 m/s is achieved in still air with heating power density of 5.0 × 1012 W/m3. For more details on the interaction between plasma synthetic jet and supersonic flow, the plasma synthetic jet induced shockwave and the disturbances in the boundary layer are numerically researched. All the results have demonstrated the control authority of plasma synthetic jet onto supersonic flow.

  17. Effect of inlet and outlet flow conditions on natural gas parameters in supersonic separation process.

    Directory of Open Access Journals (Sweden)

    Yan Yang

    Full Text Available A supersonic separator has been introduced to remove water vapour from natural gas. The mechanisms of the upstream and downstream influences are not well understood for various flow conditions from the wellhead and the back pipelines. We used a computational model to investigate the effect of the inlet and outlet flow conditions on the supersonic separation process. We found that the shock wave was sensitive to the inlet or back pressure compared to the inlet temperature. The shock position shifted forward with a higher inlet or back pressure. It indicated that an increasing inlet pressure declined the pressure recovery capacity. Furthermore, the shock wave moved out of the diffuser when the ratio of the back pressure to the inlet one was greater than 0.75, in which the state of the low pressure and temperature was destroyed, resulting in the re-evaporation of the condensed liquids. Natural gas would be the subsonic flows in the whole supersonic separator, if the mass flow rate was less than the design value, and it could not reach the low pressure and temperature for the condensation and separation of the water vapor. These results suggested a guidance mechanism for natural gas supersonic separation in various flow conditions.

  18. Influence of rarefaction on the flow dynamics of a stationary supersonic hot-gas expansion.

    Science.gov (United States)

    Abbate, G; Kleijn, C R; Thijsse, B J; Engeln, R; van de Sanden, M C M; Schram, D C

    2008-03-01

    The gas dynamics of a stationary hot-gas jet supersonically expanding into a low pressure environment is studied through numerical simulations. A hybrid coupled continuum-molecular approach is used to model the flow field. Due to the low pressure and high thermodynamic gradients, continuum mechanics results are doubtful, while, because of its excessive time expenses, a full molecular method is not feasible. The results of the hybrid coupled continuum-molecular approach proposed have been successfully validated against experimental data by R. Engeln [Plasma Sources Sci. Technol. 10, 595 (2001)] obtained by means of laser induced fluorescence. Two main questions are addressed: the necessity of applying a molecular approach where rarefaction effects are present in order to correctly model the flow and the demonstration of an invasion of the supersonic part of the flow by background particles. A comparison between the hybrid method and full continuum simulations demonstrates the inadequacy of the latter, due to the influence of rarefaction effects on both velocity and temperature fields. An analysis of the particle velocity distribution in the expansion-shock region shows clear departure from thermodynamic equilibrium and confirms the invasion of the supersonic part of the flow by background particles. A study made through particles and collisions tracking in the supersonic region further proves the presence of background particles in this region and explains how they cause thermodynamic nonequilibrium by colliding and interacting with the local particles.

  19. Lateral Reaction Jet Flow Interaction Effects on a Generic Fin-Stabilized Munition in Supersonic Crossflows

    Science.gov (United States)

    2013-11-01

    269–275. 9. Stahl, B.; Edmunds , H.; Gulhan, A. Experimental Investigation of Hot and Cold Side Jet Interaction With a Supersonic Cross Flow...LICHTENBERG-SCANLAN G MALEJKO T RECCHIA C STOUT W TOLEDO J TRAVAILLE E VAZQUEZ C WILSON 4 PM CAS (PDF) M BURKE R KIEBLER

  20. Investigation on flow and mixing characteristics of supersonic mixing layer induced by forced vibration of cantilever

    Science.gov (United States)

    Zhang, Dongdong; Tan, Jianguo; Lv, Liang

    2015-12-01

    The mixing process has been an important issue for the design of supersonic combustion ramjet engine, and the mixing efficiency plays a crucial role in the improvement of the combustion efficiency. In the present study, nanoparticle-based planar laser scattering (NPLS), particle image velocimetry (PIV) and large eddy simulation (LES) are employed to investigate the flow and mixing characteristics of supersonic mixing layer under different forced vibration conditions. The indexes of fractal dimension, mixing layer thickness, momentum thickness and scalar mixing level are applied to describe the mixing process. Results show that different from the development and evolution of supersonic mixing layer without vibration, the flow under forced vibration is more likely to present the characteristics of three-dimensionality. The laminar flow region of mixing layer under forced vibration is greatly shortened and the scales of rolled up Kelvin-Helmholtz vortices become larger, which promote the mixing process remarkably. The fractal dimension distribution reveals that comparing with the flow without vibration, the turbulent fluctuation of supersonic mixing layer under forced vibration is more intense. Besides, the distribution of mixing layer thickness, momentum thickness and scalar mixing level are strongly influenced by forced vibration. Especially, when the forcing frequency is 4000 Hz, the mixing layer thickness and momentum thickness are 0.0391 m and 0.0222 m at the far field of 0.16 m, 83% and 131% higher than that without vibration at the same position, respectively.

  1. Global Existence of a Shock for the Supersonic Flow Past a Curved Wedge

    Institute of Scientific and Technical Information of China (English)

    Hui Cheng YIN

    2006-01-01

    This note is devoted to the study of the global existence of a shock wave for the supersonic flow past a curved wedge. When the curved wedge is a small perturbation of a straight wedge and the angle of the wedge is less than some critical value, we show that a shock attached at the wedge will exist globally.

  2. CFD modeling of particle behavior in supersonic flows with strong swirls for gas separation

    DEFF Research Database (Denmark)

    Yang, Yan; Wen, Chuang

    2017-01-01

    flow from the dry gas outlet. The separation efficiency reached over 80%, when the droplet diameter was more than 1.5 μm. The optimum length of the cyclonic separation section was approximate 16–20 times of the nozzle throat diameter to obtain higher collection efficiency for the supersonic separator...

  3. Molecular dynamics computations of two dimensional supersonic rarefied gas flow past blunt bodies

    Science.gov (United States)

    Greber, Isaac; Wachman, Harold Y.; Woo, Myeung-Jouh

    1991-01-01

    This paper presents results of molecular dynamics computations of supersonic flow past a circular cylinder and past a flat plate perpendicular to a supersonic stream. The results are for Mach numbers of approximately 5 and 10, for several Knudsen numbers and several ratios of surface to free stream temperatures. A special feature of the computations is the use of relatively small numbers of particles in the molecular dynamics simulation, and an examination of the adequacy of using small numbers of particles to obtain physically useful results.

  4. Molecular dynamics computations of two dimensional supersonic rarefied gas flow past blunt bodies

    Science.gov (United States)

    Greber, Isaac; Wachman, Harold Y.; Woo, Myeung-Jouh

    1991-01-01

    This paper presents results of molecular dynamics computations of supersonic flow past a circular cylinder and past a flat plate perpendicular to a supersonic stream. The results are for Mach numbers of approximately 5 and 10, for several Knudsen numbers and several ratios of surface to free stream temperatures. A special feature of the computations is the use of relatively small numbers of particles in the molecular dynamics simulation, and an examination of the adequacy of using small numbers of particles to obtain physically useful results.

  5. The lattice Boltzmann method for isothermal micro-gaseous flow and its application in shale gas flow: a review

    CERN Document Server

    Wang, Junjian; Kang, Qinjun; Rahman, Sheik S

    2016-01-01

    The lattice Boltzmann method (LBM) has experienced tremendous advances and been well accepted as a popular method of simulation of various fluid flow mechanisms on pore scale in tight formations. With the introduction of an effective relaxation time and slip boundary conditions, the LBM has been successfully extended to solve micro-gaseous related transport and phenomena. As gas flow in shale matrix is mostly in the slip flow and transition flow regimes, given the difficulties of experimental techniques to determine extremely low permeability, it appears that the computational methods especially the LBM can be an attractive choice for simulation of these micro-gaseous flows. In this paper an extensive overview on a number of relaxation time and boundary conditions used in LBM-like models for micro-gaseous flow are carried out and their advantages and disadvantages are discussed. Furthermore, potential application of the LBM in flow simulation in shale gas reservoirs on pore scale and representative elementary...

  6. Supersonic flow onto solid wedges, multidimensional shock waves and free boundary problems

    Science.gov (United States)

    Chen, Gui-Qiang

    2017-08-01

    When an upstream steady uniform supersonic flow impinges onto a symmetric straight-sided wedge, governed by the Euler equations, there are two possible steady oblique shock configurations if the wedge angle is less than the detachment angle -- the steady weak shock with supersonic or subsonic downstream flow (determined by the wedge angle that is less or larger than the sonic angle) and the steady strong shock with subsonic downstream flow, both of which satisfy the entropy condition. The fundamental issue -- whether one or both of the steady weak and strong shocks are physically admissible solutions -- has been vigorously debated over the past eight decades. In this paper, we survey some recent developments on the stability analysis of the steady shock solutions in both the steady and dynamic regimes. For the static stability, we first show how the stability problem can be formulated as an initial-boundary value type problem and then reformulate it into a free boundary problem when the perturbation of both the upstream steady supersonic flow and the wedge boundary are suitably regular and small, and we finally present some recent results on the static stability of the steady supersonic and transonic shocks. For the dynamic stability for potential flow, we first show how the stability problem can be formulated as an initial-boundary value problem and then use the self-similarity of the problem to reduce it into a boundary value problem and further reformulate it into a free boundary problem, and we finally survey some recent developments in solving this free boundary problem for the existence of the Prandtl-Meyer configurations that tend to the steady weak supersonic or transonic oblique shock solutions as time goes to infinity. Some further developments and mathematical challenges in this direction are also discussed.

  7. The calibration and operation of a constant-temperature crossed-wire probe in supersonic flow

    Science.gov (United States)

    Fernando, E. M.; Donovan, J. F.; Smits, A. J.

    1987-01-01

    The calibration and operation of a constant-temperature crossed-wire probe in supersonic flow is considered. Crossed-wire probes offer considerable advantages over single, inclined wires: the kinematic shear stress can be derived from a single point measurement; the rms quantities can be derived from the same measurement, and the instantaneous quantities can be obtained as a continuous function of time. However, using a crossed-wire probe in supersonic flow is subject to the following practical difficulties: the problem of flow interference, where the shock waves from one wire and its supports interfere with the flow over the other wire; the necessity for high frequency response to resolve the spectral content, and the sensitivity of the results to small changes in the calibration constants. In the present contribution, each of these problems is addressed. Practical solutions are suggested, and some encouraging results are presented.

  8. LES of an inclined jet into a supersonic cross-flow

    CERN Document Server

    Ferrante, Antonino; Matheou, Georgios; Dimotakis, Paul E; Stephens, Mike; Adams, Paul; Walters, Richard; Hand, Randall

    2008-01-01

    This short article describes flow parameters, numerical method, and animations of the fluid dynamics video LES of an Inclined Jet into a Supersonic Cross-Flow (http://hdl.handle.net/1813/11480). Helium is injected through an inclined round jet into a supersonic air flow at Mach 3.6. The video shows 2D contours of Mach number and magnitude of density gradient, and 3D iso-surfaces of Helium mass-fraction and vortical structures. Large eddy simulation with the sub-grid scale (LES-SGS) stretched vortex model of turbulent and scalar transport captures the main flow features: bow shock, Mach disk, shear layers, counter-rotating vortices, and large-scale structures.

  9. Parameters of the plasma of a dc pulsating discharge in a supersonic air flow

    Energy Technology Data Exchange (ETDEWEB)

    Shibkov, V. M., E-mail: shibkov@phys.msu.ru; Shibkova, L. V.; Logunov, A. A. [Moscow State University, Faculty of Physics (Russian Federation)

    2017-03-15

    A dc discharge in a cold (T = 200 K) supersonic air flow at a static pressure of 200–400 Torr was studied experimentally. The excited unsteady pulsating discharge has the form of a thin plasma channel with a diameter of ≤1 mm, stretched downstream the flow. Depending on the discharge current, the pulsation frequency varies from 800 to 1600 Hz and the electron temperature varies from 8000 to 15000 K.

  10. ON THE ASYMPTOTIC BEHAVIOUR OF THE STEADY SUPERSONIC FLOWS AT INFINITY

    Institute of Scientific and Technical Information of China (English)

    ZHANG YONGQIAN

    2005-01-01

    This paper studies the asymptotic behaviour of steady supersonic flow past a piecewise smooth corner or bend. Under the hypothese that both vertex angle and the total variation of tangent along the boundary are small, it is shown that the solution can be obtained by a modified Glimm scheme, and that the asymptotic behaviour of the solution is determined by the velocity of incoming flow and the limit of the tangent of the boundary at infinity.

  11. Detonation in supersonic radial outflow

    KAUST Repository

    Kasimov, Aslan R.

    2014-11-07

    We report on the structure and dynamics of gaseous detonation stabilized in a supersonic flow emanating radially from a central source. The steady-state solutions are computed and their range of existence is investigated. Two-dimensional simulations are carried out in order to explore the stability of the steady-state solutions. It is found that both collapsing and expanding two-dimensional cellular detonations exist. The latter can be stabilized by putting several rigid obstacles in the flow downstream of the steady-state sonic locus. The problem of initiation of standing detonation stabilized in the radial flow is also investigated numerically. © 2014 Cambridge University Press.

  12. Advanced Supersonic Nozzle Concepts: Experimental Flow Visualization Results Paired With LES

    Science.gov (United States)

    Berry, Matthew; Magstadt, Andrew; Stack, Cory; Gaitonde, Datta; Glauser, Mark; Syracuse University Team; The Ohio State University Team

    2015-11-01

    Advanced supersonic nozzle concepts are currently under investigation, utilizing multiple bypass streams and airframe integration to bolster performance and efficiency. This work focuses on the parametric study of a supersonic, multi-stream jet with aft deck. The single plane of symmetry, rectangular nozzle, displays very complex and unique flow characteristics. Flow visualization techniques in the form of PIV and schlieren capture flow features at various deck lengths and Mach numbers. LES is compared to the experimental results to both validate the computational model and identify limitations of the simulation. By comparing experimental results to LES, this study will help create a foundation of knowledge for advanced nozzle designs in future aircraft. SBIR Phase II with Spectral Energies, LLC under direction of Barry Kiel.

  13. Imaging of the Space-time Structure of a Vortex Generator in Supersonic Flow

    Institute of Scientific and Technical Information of China (English)

    WANG Dengpan; XIA Zhixun; ZHAO Yuxin; WANG Bo; ZHAO Yanhui

    2012-01-01

    The fine space-time structure of a vortex generator (VG) in supersonic flow is studied with the nanoparticle-based planar laser scattering (NPLS) method in a quiet supersonic wind tunnel.The fine coherent structure at the symmetrical plane of the flow field around the VG is imaged with NPLS.The spatial structure and temporal evolution characteristics of the vortical structure are analyzed,which demonstrate periodic evolution and similar geometry,and the characteristics of rapid movement and slow change.Because the NPLS system yields the flow images at high temporal and spatial resolutions,from these images the position of a large scale structure can be extracted precisely.The position and velocity of the large scale structures can be evaluated with edge detection and correlation algorithms.The shocklet structures induced by vortices are imaged,from which the generation and development of shocklets are discussed in this paper.

  14. An Experimental Study of Turbulent Skin Friction Reduction in Supersonic Flow Using a Microblowing Technique

    Science.gov (United States)

    Hwang, Danny P.

    1999-01-01

    A new turbulent skin friction reduction technology, called the microblowing technique has been tested in supersonic flow (Mach number of 1.9) on specially designed porous plates with microholes. The skin friction was measured directly by a force balance and the boundary layer development was measured by a total pressure rake at the tailing edge of a test plate. The free stream Reynolds number was 1.0(10 exp 6) per meter. The turbulent skin friction coefficient ratios (C(sub f)/C(sub f0)) of seven porous plates are given in this report. Test results showed that the microblowing technique could reduce the turbulent skin friction in supersonic flow (up to 90 percent below a solid flat plate value, which was even greater than in subsonic flow).

  15. Elliptic Length Scales in Laminar, Two-Dimensional Supersonic Flows

    Science.gov (United States)

    2015-06-01

    adiabatic wall flows over compression ramps and flows with shock impingements. The new correlations are derived from existing numerical data and...developed for 2D, laminar adiabatic wall flows over compression ramps and flows with shock impingements. These correlations are derived from existing...characterizing the influence of shocks and compression ramps on flat plate flows is presented. New correlations for laminar compressive interactions on

  16. CFD-Exergy analysis of the flow in a supersonic steam ejector

    Science.gov (United States)

    Boulenouar, M.; Ouadha, A.

    2015-01-01

    The current study aims to carry out a CFD-exergy based analysis to assess the main areas of loss in a supersonic steam ejector encountered in ejector refrigeration systems. The governing equations for a compressible flow are solved using finite volume approach based on SST k-ω model to handle turbulence effects. Flow rates and the computed mean temperatures and pressures have been used to calculate the exergy losses within the different regions of the ejector as well as its overall exergy efficiency. The primary mass flow rate, the secondary mass flow rate and the entrainment ratio predicted by the model have been compared with the experimental data from the literature.

  17. Expansion Waves at the Outlet of the Supersonic Two-Phase Flow Nozzle

    Science.gov (United States)

    Nakagawa, Masafumi; Miyazaki, Hiroki; Harada, Atsushi; Ibragimov, Zokirjon

    Two-phase flow nozzles are used in the total flow system of geothermal power plants and in the ejector of the refrigeration cycle, etc. One of the most important functions of the two-phase flow nozzle is converting two-phase flow thermal energy into kinetic energy. The kinetic energy of the two-phase flow exhausted from a nozzle is available for all applications of this type. In the case of non-best fitting expansion conditions, when the operation conditions of the supersonic nozzle are widely chosen, there exist shock waves or expansion waves at the outlet of the nozzle. Those waves affect largely the energy conversion efficiency of the two-phase flow nozzle. The purpose of the present study is to elucidate character of the expansion waves at the outlet of the supersonic two-phase flow nozzle. High-pressure hot water blowdown experiments have been carried out. The decompression curves of the expansion waves are measured by changing the flowrate in the nozzle and inlet temperature of the hot water. The back pressures of the nozzle are also changed in those experiments. The expansion angles of the two-phase flow flushed out from the nozzle are measured by means of the photograph. The experimental results show that the decompression curves are different from those predicted by the isentropic homogeneous two-phase flow theory. The regions where the expansion waves occur become wide due to the increased outlet speed of the two-phase flow. The qualitative dependency of this expansion character is the same as the isentropic homogeneous flow, but the values obtained from the experiments are quite different. When the back pressure of the nozzle is higher, these regions do not become small in spite of the supersonic two-phase flow. This means that the disturbance in the downstream propagates to the upstream. It is shown by the present experiments that the expansion waves in the supersonic two-phase flow of water have a subsonic feature. The measured expansion angles become

  18. A flow control study of a supersonic mixing layer via NPLS

    Institute of Scientific and Technical Information of China (English)

    2009-01-01

    The flow control of a supersonic mixing layer was studied in a supersonic mixing layer wind tunnel with convective Mach number (Mc) at 0.5. The passive control of the mixing layer was achieved by perturbation tapes on the trailing edge of the splitter plate. The control effects of 2D and 3D perturbation tapes with different sizes were compared. The mixing layer was visualized via NPLS,and the transient fine structures were identifiable in NPLS images,which were used to analyze the effects of flow control. The results show that the 2D tapes can enhance the 2D characteristic of the mixing layer,delaying mixing layer transition; and the 3D tapes can enhance the 3D characteristic of the mixing layer,advancing mixing layer transition. 3D structures of the mixing layer were visualized,and the H-type Λ vortexes were found with 3D tapes control.

  19. Cavity Ignition in Supersonic Flow by Spark Discharge and Pulse Detonation

    Science.gov (United States)

    2014-08-18

    constant volume, through a detonation , or some combination. While a deflagration (flame) through constant volume combustion can provide rapid heat release...significantly disrupted, and the detonation was able to ignite and burn most of the fuel within the cavity. This led to decreased heat release in regime IV...locate/proci of the Combustion InstituteCavity ignition in supersonic flow by spark discharge and pulse detonation Timothy M. Ombrello a,⇑, Campbell D

  20. Nonlinear effects of energy sources and the jet at supersonic flow in the channel

    Science.gov (United States)

    Zamuraev, V. P.; Kalinina, A. P.

    2016-10-01

    The work is devoted to the mathematical modeling of the influence of transversal jet and the near-wall energy sources on the shock wave structure of supersonic flow in channel with variable cross section. Stable regimes with the region of transonic velocities are obtained. Their stability is confirmed by the width of the corridor of the input power in the area of the regime existence.

  1. Nonlinear vibrations of cylindrical shells with initial imperfections in a supersonic flow

    Science.gov (United States)

    Kurilov, E. A.; Mikhlin, Yu. V.

    2007-09-01

    The paper studies the dynamics of nonlinear elastic cylindrical shells using the theory of shallow shells. The aerodynamic pressure on the shell in a supersonic flow is found using piston theory. The effect of the flow and initial deflections on the vibrations of the shell is analyzed in the flutter range. The normal modes of both perfect shells in a flow and shells with initial imperfections are studied. In the latter case, the trajectories of normal modes in the configuration space are nearly rectilinear, only one mode determined by the initial imperfections being stable

  2. Fundamental Structure of High-Speed Reacting Flows: Supersonic Combustion and Detonation

    Science.gov (United States)

    2016-04-30

    supersonic. Oblique Shock Interface Inert Reactants β θ P1 P2e P3eUCJ P1 UCJ P2i Detonation Figure 3. Idealized flow model of a detonation wave with an...Propagation With No Confinement But With Transvers Flow A consistent cross-flow was established by calibrating the height of the gases in time relative...to the controller commands, and then staggering the triggering of the gases such that each species – hydrogen, helium, and oxygen – independently

  3. A Computer Program to Calculate the Supersonic Flow over a Solid Cone in Air or Water.

    Science.gov (United States)

    1984-06-01

    ix air or water. The rain objective is to calculate the ccne semi-vertei angle given prescribed initial ccndi- tions. The program is written in...tc the motion of the metal jet frcm an explczive shaped-charge fired underwater. A tiical result for supersonic flow over a ccne in water is as follcws...the ccne semi-vertex angle is calculated to be 7.23 degrees. Gene rally, pressures invclved in water flow are much larger than for air flow, and the

  4. Numerical Investigation of Supersonic Oscillatory Flow with Strong Interference over a Capsule-shaped Abort System

    Science.gov (United States)

    Wang, Yunpeng; Ozawa, Hiroshi; Nakamura, Yoshiaki

    The flow past a capsule-shaped space transportation system (STS) is numerically analyzed using computational fluid dynamics (CFD) for different free stream Mach numbers ranging from 1.2 to 5.0, where a capsule is modeled by a cone, and a rocket by a circular cylinder. The objective of this research is to study Mach number effects on phenomena of the supersonic aerodynamic interference with periodic flow oscillations at supersonic regime. So far we have considered two models: model A (without disk) and model B (with disk). It was found from experimental and computational results that the flow around model A becomes steady, where aerodynamic interaction is not observed, while in model B, flow becomes unsteady with periodic oscillations. This flow oscillation is considered to be a potentially high risk in separation of the capsule and rocket. Therefore, the present study focuses on the unsteady case of model B. Numerical results at M=3.0 compared well with experimental ones, which validates the present CFD. Time-averaged results are employed to see the whole trajectories of shock waves and the variation in amplitude of flow oscillation during one cycle. Moreover, a fence is proposed as a device to suppress the flow oscillation.

  5. Rarefaction Waves at the Outlet of the Supersonic Two-Phase Flow Nozzle

    Science.gov (United States)

    Nakagawa, Masafumi; Miyazaki, Hiroki; Harada, Atsushi

    Two-phase flow nozzles are used in the total flow system for geothermal power plants and in the ejector of the refrigerant cycle, etc. One of the most important functions of a two-phase flow nozzle is to convert the thermal energy to the kinetic energy of the two-phase flow. The kinetic energy of the two-phase flow exhausted from a nozzle is available for all applications of this type. There exist the shock waves or rarefaction waves at the outlet of a supersonic nozzle in the case of non-best fitting expansion conditions when the operation conditions of the nozzle are widely chosen. Those waves affect largely on the energy conversion efficiency of the two-phase flow nozzle. The purpose of the present study is to elucidate the character of the rarefaction waves at the outlet of the supersonic two-phase flow nozzle. The high pressure hot water blow down experiment has been carried out. The decompression curves by the rarefaction waves are measured by changing the flow rate of the nozzle and inlet temperature of the hot water. The back pressures of the nozzle are also changed in those experiments. The divergent angles of the two-phase flow flushed out from the nozzle are measured by means of the photograph. The experimental results show that the recompression curves are different from those predicted by the isentropic homogenous two-phase flow. The regions where the rarefaction waves occur become wide due to the increased outlet speed of two-phase flow. The qualitative dependency of this expansion character is the same as the isotropic homogenous flow, but the values obtained from the experiments are quite different. When the back pressure of the nozzle is higher, these regions do not become small in spite of the super sonic two-phase flow. This means that the disturbance of the down-stream propagate to the up-stream. It is shown by the present experiments that the rarefaction waves in the supersonic two-phase flow of water have a subsonic feature. The measured

  6. Behavior of Boundary Layer in Supersonic Flow with Applied Lorentz Force

    Science.gov (United States)

    Udagawa, Keisuke; Saito, Shinya; Kawaguchi, Kenji; Tomioka, Sadatake; Yamasaki, Hiroyuki

    Experimental study on behavior of boundary layer in supersonic flow with applied Lorentz force was carried out. In the experiment, Mach 1.5 supersonic wind tunnel driven by a shock-tube was used. At the test section, the current from the external DC power supply and the magnetic field of 2.4 Tesla were applied to the boundary layer developing on the bottom wall. Argon seeded with cesium was used as an electrically conducting gas. Effect of the direction of the Lorentz force on static pressure distribution was investigated, and the remarkable increase of static pressure at the test section was observed for the decelerating Lorentz force. It is noted that the acceleration of the flow inside the boundary layer was demonstrated for the first time without accelerating the main flow when the accelerating Lorentz force was applied. At the same time, the acceleration efficiency defined by a ratio of work done by the Lorentz force to energy input into the flow was found 54-61%. These results have suggested the possibility of the boundary layer separation control by applying the accelerating Lorentz force. In the case of the decelerating Lorentz force, the significant reduction of Mach number was observed not only inside the boundary layer but also in the main flow. The reduction of Mach number could be ascribed to the growth of the boundary layer due to gas heating inside the boundary layer. When the direction of the current was changed, the difference of light emission from the discharge inside the boundary layer was observed, and this was due to the difference of the electromotive force induced in the supersonic flow.

  7. Optical studies of shock generated transient supersonic base flows

    Science.gov (United States)

    Liang, P.-Y.; Bershader, D.; Wray, A.

    1982-01-01

    A shock tube employing interferometric and schlieren techniques is used to study transient base flow phenomena following shock wave passage over two plane bluff bodies: a hemicircular cylinder and a cylinder with the Galileo Jovian probe profile. An attempt is made to understand the physics of transition from transient to steady state flow, and to provide code verification for a study employing the Illiac IV computer. Transient base flow interactions include a series of shock diffraction, regular, and Mach reflections, coupled with boundary layer development, separation, and recompression. Vorticity generation and transport underlie these features. The quantitative verification of the computer code includes comparisons of transient pressure and density fields, near wake geometries, and bow shock standoff distances.

  8. Improved optical techniques for studying sonic and supersonic injection into Mach 3 flow

    Science.gov (United States)

    Buggele, Alvin E.; Seasholtz, Richard G.

    1997-11-01

    Filtered Rayleigh Scattering and shadowgraph flow visualization were used to characterize the penetration of helium or moist air injected transversely at several pressures to a Mach 3 flow in the NASA Lewis 3.81 inch by 10 inch continuous flow supersonic wind tunnel. This work is in support of the LOX augmented nuclear thermal rocket program. The present study used an injection-seeded, frequency doubled Nd:YAG pulsed laser to illuminate a transverse section of the injectant plume. Rayleigh scattered light was passed through an iodine absorption cell to suppress stray laser light and was imaged onto a cooled CCD camera. The scattering was based on condensation of water vapor in the injectant flow. Results are presented for various configurations of sonic and supersonic injector designs mounted primarily in the floor of the tunnel. Injectors studied include a single 0.25 inch diameter hole, five 0.112 inch diameter holes on 0.177 inch spacing, and a 7 degree half angle wedge. High speed shadowgraph flow visualization images were obtained with several video camera systems. Roof and floor static pressure data are presented several ways for the three configurations of injection designs with and without helium and/or air injection into Mach 3 flow.

  9. Unsteady flow in a supersonic cascade with subsonic leading-edge locus

    Science.gov (United States)

    Adamczyk, J. J.; Goldstein, M. E.

    1978-01-01

    Linearized theory is used to predict the unsteady flow in a supersonic cascade with subsonic axial flow velocity. A closed-form analytical solution is obtained by using a double application of the Wiener-Hopf technique. Although numerical and semianalytical solutions of this problem have already appeared in the literature, this paper contains the first completely analytical solution. It has been stated in the literature that the blade source should vanish at the infinite duct resonance condition. The present analysis shows that this does not occur. This apparent discrepancy is explained in the paper.

  10. Constant-temperature hot-wire anemometer practice in supersonic flows. I - The normal wire

    Science.gov (United States)

    Smits, A. J.; Hayakawa, K.; Muck, K. C.

    1983-01-01

    The performance of a constant-temperature normal hot-wire in a supersonic flow is critically examined. It is shown that this instrument is inherently unsuitable for measuring turbulent temperature correlations because of the highly nonlinear response to temperature fluctuations, particularly at low overheat ratios. The instrument is therefore limited to measurements of mean and fluctuating mass-flow rates. Suitable calibration procedures, as well as the limits on spatial and temporal resolution are discussed, and corrections for mean stagnation temperature changes are suggested.

  11. Computations of the Magnus effect for slender bodies in supersonic flow

    Science.gov (United States)

    Sturek, W. B.; Schiff, L. B.

    1980-01-01

    A recently reported Parabolized Navier-Stokes code has been employed to compute the supersonic flow field about spinning cone, ogive-cylinder, and boattailed bodies of revolution at moderate incidence. The computations were performed for flow conditions where extensive measurements for wall pressure, boundary layer velocity profiles and Magnus force had been obtained. Comparisons between the computational results and experiment indicate excellent agreement for angles of attack up to six degrees. The comparisons for Magnus effects show that the code accurately predicts the effects of body shape and Mach number for the selected models for Mach numbers in the range of 2-4.

  12. Photodissociation of Isoxazole and Pyridine Studied Using Chirped Pulse Microwave Spectroscopy in Pulsed Uniform Supersonic Flows

    Science.gov (United States)

    Ariyasingha, Nuwandi M.; Joalland, Baptiste; Mebel, Alexander M.; Suits, Arthur

    2016-06-01

    Chirped - Pulse Fourier-transform microwave spectroscopy in uniform supersonic flows (Chirped- Pulse/Uniform Flow: CPUF) has been applied to study the photodissociation of two atmospherically relevant N containing heterocyclic compounds; pyridine and isoxazole. Products were detected using rotational spectroscopy. HC3N, HCN were observed for pyridine and CH3CN, HCO and HCN were observed for isoxazole and we report the first detection of HNC for both of the systems. Key points in potential energy surface were explored and compared with the experimental observations. Branching ratios were calculated for all the possible channels and will be presented.

  13. IRROTATIONAL APPROXIMATION TO STEADY SUPERSONIC FLOW IN TWO SPACE VARIABLES

    Institute of Scientific and Technical Information of China (English)

    Liu Chong

    2008-01-01

    On the assumption that the total variation of the initial data is sufficiently small,we can use the stability results of Dafermos to get the L2 estimate of the difference between the solutions to the isentropic steady Euler system and the potential flow equations with the same initial data.

  14. Supersonic flow of a nonequilibrium gas-discharge plasma around a body

    Science.gov (United States)

    Lapushkina, T. A.; Erofeev, A. V.; Ponyaev, S. A.; Bobashev, S. V.

    2009-06-01

    The flow of a nonequilibrium gas-discharge plasma around a semicylindrical body is studied. The aim of the study is to see how a change in the degree of nonequilibrium of the incoming plasma changes the separation distance between a shock wave and the body. Experiments are carried out with a supersonic nozzle into which a semicylindrical body is placed. The inlet of the nozzle is connected to a shock tube. In the course of the experiment, electrodes built into the wall of the nozzle initiate a gas discharge in front of the body to produce an additional nonequilibrium ionization in the stationary incoming supersonic flow. The discharge parameters are selected such that the discharge raises the electron temperature and still minimizes heating of the gas. The degree of nonequilibrium of the flow varies with gas-discharge current. Diagnostics of the flow is carried out with a schlieren system based on a semiconductor laser. The system can record flow patterns at definite time instants after discharge initiation.

  15. Analysis of flow structures in supersonic plane mixing layers using the POD method

    Institute of Scientific and Technical Information of China (English)

    YANG Qin; FU Song

    2008-01-01

    The proper orthogonal decomposition (POD) method was applied to analyzing the database obtained from the direct numerical simulation (DNS) of supersonic plane mixing layers. The effect of different forms of the inner products in the POD method was investigated. It was observed that the mean flow contributes to a predominant part of the total flow energy, and the energy spectrum of the turbulence fluctuations covers a wide range of POD modes. The patterns of leading (high energy) POD modes reveal that the flow structures exhibit spanwise counter rotating rolls, as well as oblique vortices. These flow patterns are insensitive to the velocity of the observer. As the convective Mach number increases, the energy spectrum be-comes wider, the leading POD modes contain more complicated structures, and the flow becomes more chaotic.

  16. Analysis of flow structures in supersonic plane mixing layers using the POD method

    Institute of Scientific and Technical Information of China (English)

    2008-01-01

    The proper orthogonal decomposition(POD) method was applied to analyzing the database obtained from the direct numerical simulation(DNS) of supersonic plane mixing layers.The effect of different forms of the inner products in the POD method was investigated.It was observed that the mean flow contributes to a predominant part of the total flow energy,and the energy spectrum of the turbulence fluctuations covers a wide range of POD modes.The patterns of leading(high energy) POD modes reveal that the flow structures exhibit spanwise counter rotating rolls,as well as oblique vortices.These flow patterns are insensitive to the velocity of the observer.As the convective Mach number increases,the energy spectrum be-comes wider,the leading POD modes contain more complicated structures,and the flow becomes more chaotic.

  17. Plasma-based Control of Supersonic Nozzle Flow

    CERN Document Server

    Gaitonde, Datta V

    2009-01-01

    The flow structure obtained when Localized Arc Filament Plasma Actuators (LAFPA) are employed to control the flow issuing from a perfectly expanded Mach 1.3 nozzle is elucidated by visualizing coherent structures obtained from Implicit Large-Eddy Simulations. The computations reproduce recent experimental observations at the Ohio State University to influence the acoustic and mixing properties of the jet. Eight actuators were placed on a collar around the periphery of the nozzle exit and selectively excited to generate various modes, including first and second mixed (m = +/- 1 and m = +/- 2) and axisymmetric (m = 0). In this fluid dynamics video http://ecommons.library.cornell.edu/bitstream/1813/13723/2/Alljoinedtotalwithmodetextlong2-Datta%20MPEG-1.m1v, http://ecommons.library.cornell.edu/bitstream/1813/13723/3/Alljoinedtotalwithmodetextlong2-Datta%20MPEG-2.m2v}, unsteady and phase-averaged quantities are displayed to aid understanding of the vortex dynamics associated with the m = +/- 1 and m = 0 modes exci...

  18. Blast shocks in quasi-two-dimensional supersonic granular flows.

    Science.gov (United States)

    Boudet, J F; Cassagne, J; Kellay, H

    2009-11-27

    In a thin, dilute, and fast flowing granular layer, the impact of a small sphere generates a fast growing hole devoid of matter. The growth of this hole is studied in detail, and its dynamics is found to mimic that of blast shocks in gases. This dynamics can be decomposed into two stages: a fast initial stage (the blast) and a slower growth regime whose growth velocity is given by the speed of sound in the medium used. A simple model using ingredients already invoked for the case of blast shocks in gases but including the inelastic nature of collisions between grains accounts accurately for our results. The system studied here allows for a detailed study of the full dynamics of a blast as it relaxes from a strong to a weak shock and later to an acoustic disturbance.

  19. Shock front width and structure in supersonic granular flows.

    Science.gov (United States)

    Boudet, J F; Amarouchene, Y; Kellay, H

    2008-12-19

    The full structure of a shock front around a blunt body in a quasi-two-dimensional granular flow is studied. Two features, a large density gradient and a very small thickness of the front, characterize this shock and make it different from shocks in molecular gases. Both of these features can be understood using a modified version of the granular kinetic theory. Our model separates the particles into two subpopulations: fast particles having experienced no collisions and randomly moving particles. This separation is motivated by direct measurements of the particle velocities which show a bimodal distribution. Our results not only shed new light on the use of the granular kinetic theory under extreme conditions (shock formation) but bring new insight into the physics of shocks in general.

  20. Tangential injection to a supersonic flow on a blunted nose

    Science.gov (United States)

    Chuvakhov, P. V.; Egorov, I. V.; Ezhov, I. V.; Ezhov, I. V.; Novikov, I. V.; Vasilevskiy, E. B.

    2017-06-01

    The flow pattern and the heat §ux to a body surface at a tangential gas injecting have been investigated. The cooling air was injected to a §ow through the tangential axisymmetric slot on the spherically blunted cylinder. The experiments were conducted at M∞ = 6, Re∞,Rw = 0.76 · 106, angle of attack α = 0°-30°, and the slot width hk/Rw = 0-0.021. The mass rate of the injecting gas was G∗ = gj/(πρ∞ u2∞w) = 0- 0.16. It has been shown that maximum of the heat §ux toward the sphere surface can be sufficiently decreased. Numerical investigations have been carried out using the solution of the Navier-Stokes equations for axisymmetric two-dimensional (2D) viscous compressible unsteady §ows at α = 0.

  1. Numerical Simulation of Reactive Flows in Overexpanded Supersonic Nozzle with Film Cooling

    Directory of Open Access Journals (Sweden)

    Mohamed Sellam

    2015-01-01

    Full Text Available Reignition phenomena occurring in a supersonic nozzle flow may present a crucial safety issue for rocket propulsion systems. These phenomena concern mainly rocket engines which use H2 gas (GH2 in the film cooling device, particularly when the nozzle operates under over expanded flow conditions at sea level or at low altitudes. Consequently, the induced wall thermal loads can lead to the nozzle geometry alteration, which in turn, leads to the appearance of strong side loads that may be detrimental to the rocket engine structural integrity. It is therefore necessary to understand both aerodynamic and chemical mechanisms that are at the origin of these processes. This paper is a numerical contribution which reports results from CFD analysis carried out for supersonic reactive flows in a planar nozzle cooled with GH2 film. Like the experimental observations, CFD simulations showed their ability to highlight these phenomena for the same nozzle flow conditions. Induced thermal load are also analyzed in terms of cooling efficiency and the results already give an idea on their magnitude. It was also shown that slightly increasing the film injection pressure can avoid the reignition phenomena by moving the separation shock towards the nozzle exit section.

  2. Review:Progress in research on mixing techniques for transverse injection flow fields in supersonic crossflows

    Institute of Scientific and Technical Information of China (English)

    Wei HUANG; Li YAN

    2013-01-01

    The transverse injection flow field has an important impact on the flowpath design of scramjet engines.At present a combination of the transverse injection scheme and any other flame holder has been widely employed in hypersonic propulsion systems to promote the mixing process between the fuel and the supersonic freestream;combustion efficiency has been improved thereby,as well as engine thrust.Research on mixing techniques for the transverse injection flow field is summarized from four aspects,namely the jet-to-crossflow pressure ratio,the geometric configuration of the injection port,the number of injection ports,and the injection angle.In conclusion,urgent investigations of mixing techniques of the transverse injection flow field are proposed,especially data mining in the quantitative analytical results for transverse injection flow field,based on results from multi-objective design optimization theory.

  3. Aerodynamic Study on Supersonic Flows in High-Velocity Oxy-Fuel Thermal Spray Process

    Institute of Scientific and Technical Information of China (English)

    Hiroshi KATANODA; Takeshi MATSUOKA; Seiji KURODA; Jin KAWAKITA; Hirotaka FUKANUMA; Kazuyasu MATSUO

    2005-01-01

    @@ To clarify the characteristics of gas flow in high velocity oxy-fuel (HVOF) thermal spray gun, aerodynamic research is performed using a special gun. The gun has rectangular cross-sectional area and sidewalls of optical glass to visualize the internal flow. The gun consists of a supersonic nozzle with the design Mach number of 2.0 followed by a straight passage called barrel. Compressed dry air up to 0.78 MPa is used as a process gas instead of combustion gas which is used in a commercial HVOF gun. The high-speed gas flows with shock waves in the gun and jets are visualized by schlieren technique. Complicated internal and external flow-fields containing various types of shock wave as well as expansion wave are visualized.

  4. Nonlinear unsteady supersonic flow analysis for slender bodies of revolution: Theory

    Directory of Open Access Journals (Sweden)

    D. E. Panayotounakos

    1997-01-01

    Full Text Available We construct analytical solutions for the problem of nonlinear supersonic flow past slender bodies of revolution due to small amplitude oscillations. The method employed is based on the splitting of the time dependent small perturbation equation to a nonlinear time independent partial differential equation (P.D.E. concerning the steady flow, and a linear time dependent one, concerning the unsteady flow. Solutions in the form of three parameters family of surfaces for the first equation are constructed, while solutions including one arbitrary function for the second equation are extracted. As an application the evaluation of the small perturbation velocity resultants for a flow past a right circular cone is obtained making use of convenient boundary and initial conditions in accordance with the physical problem.

  5. Flow characteristics and micro-scale metallic particle formation in the laser supersonic heating technique

    Science.gov (United States)

    Lin, Shih-Lung; Lin, Jehnming

    2007-02-01

    The characteristics of the supersonic flow of the laser heating technique for producing micro-scale metallic particles were investigated in this study. A numerical model was established to predict the flow fields and particle trajectories leaving a spray nozzle with shock wave effects. The compressible flow of the shock waves and the trajectories of particles in diameters of 1-20 μm were simulated and compared with the flow visualization. In the experiment, a pulsed Nd-YAG laser was used as heat source on a carbon steel target within the nozzle, and the carbon steel particles were ejected by high-pressure air. The result shows that the shock wave structures were generated at various entrance pressures, and there is a significant increase in the amount of carbon steel particles and the spraying angles by increasing the entrance air pressure.

  6. High angle of attack aerodynamics subsonic, transonic, and supersonic flows

    CERN Document Server

    Rom, Josef

    1992-01-01

    The aerodynamics of aircraft at high angles of attack is a subject which is being pursued diligently, because the modern agile fighter aircraft and many of the current generation of missiles must perform well at very high incidence, near and beyond stall. However, a comprehensive presentation of the methods and results applicable to the studies of the complex aerodynamics at high angle of attack has not been covered in monographs or textbooks. This book is not the usual textbook in that it goes beyond just presenting the basic theoretical and experimental know-how, since it contains reference material to practical calculation methods and technical and experimental results which can be useful to the practicing aerospace engineers and scientists. It can certainly be used as a text and reference book for graduate courses on subjects related to high angles of attack aerodynamics and for topics related to three-dimensional separation in viscous flow courses. In addition, the book is addressed to the aerodynamicist...

  7. Dense core formation in supersonic turbulent converging flows

    CERN Document Server

    Gong, Hao

    2011-01-01

    We use numerical hydrodynamic simulations to investigate prestellar core formation in the dynamic environment of giant molecular clouds, focusing on planar post-shock layers produced by colliding turbulent flows. A key goal is to test how core evolution and properties depend on the velocity dispersion in the parent cloud; our simulation suite consists of 180 models with inflow Mach numbers Ma=v/c_s=1.1-9. At all Mach numbers, our models show that turbulence and self-gravity collect gas within post-shock regions into filaments at the same time as overdense areas within these filaments condense into cores. This morphology, together with the subsonic velocities we find inside cores, is similar to observations. We extend previous results showing that core collapse develops in an ``outside-in'' manner, with density and velocity approaching the Larson-Penston asymptotic solution. The time for the first core to collapse varies as 1/sqrt(v), consistent with analytic estimates. Core building takes 10 times as long as ...

  8. Detector for flow abnormalities in gaseous diffusion plant compressors

    Science.gov (United States)

    Smith, S.F.; Castleberry, K.N.

    1998-06-16

    A detector detects a flow abnormality in a plant compressor which outputs a motor current signal. The detector includes a demodulator/lowpass filter demodulating and filtering the motor current signal producing a demodulated signal, and first, second, third and fourth bandpass filters connected to the demodulator/lowpass filter, and filtering the demodulated signal in accordance with first, second, third and fourth bandpass frequencies generating first, second, third and fourth filtered signals having first, second, third and fourth amplitudes. The detector also includes first, second, third and fourth amplitude detectors connected to the first, second, third and fourth bandpass filters respectively, and detecting the first, second, third and fourth amplitudes, and first and second adders connected to the first and fourth amplitude detectors and the second and third amplitude detectors respectively, and adding the first and fourth amplitudes and the second and third amplitudes respectively generating first and second added signals. Finally, the detector includes a comparator, connected to the first and second adders, and comparing the first and second added signals and detecting the abnormal condition in the plant compressor when the second added signal exceeds the first added signal by a predetermined value. 6 figs.

  9. CFD modelling of condensation process of water vapor in supersonic flows

    DEFF Research Database (Denmark)

    Wen, Chuang; Walther, Jens Honore; Yan, Yuying;

    2016-01-01

    -liquid phase change both in space and in time. The spontaneous condensation of water vapor will not appear immediately when the steam reaches the saturation state. Instead, it occurs further downstream the nozzle throat, where the steam is in the state of supersaturation.......The condensation phenomenon of vapor plays an important role in various industries, such as the steam flow in turbines and refrigeration system. A mathematical model is developed to predict the spontaneous condensing phenomenon in the supersonic conditions using the nucleation and droplet growth...

  10. Computing 3-D steady supersonic flow via a new Lagrangian approach

    Science.gov (United States)

    Loh, C. Y.; Liou, M.-S.

    1993-01-01

    The new Lagrangian method introduced by Loh and Hui (1990) is extended for 3-D steady supersonic flow computation. Details of the conservation form, the implementation of the local Riemann solver, and the Godunov and the high resolution TVD schemes are presented. The new approach is robust yet accurate, capable of handling complicated geometry and reactions between discontinuous waves. It keeps all the advantages claimed in the 2-D method of Loh and Hui, e.g., crisp resolution for a slip surface (contact discontinuity) and automatic grid generation along the stream.

  11. Experimental study on atomization phenomena of kerosene in supersonic cold flow

    Institute of Scientific and Technical Information of China (English)

    FEI LiSen; XU ShengLi; WANG ChangJian; LI Qiang; HUANG ShengHong

    2008-01-01

    Experiments were conducted to study the atomization phenomena of kerosene jet in supersonic flow. The kerosene jet was driven by compressed nitrogen. Meanwhile, the shadowgraph and planar laser-induced fluorescence (PLIF) were used to visualize the flow field in the case of different total pressure and jet pressure. The results imply the followings: The combination of shadowgraph and PLIF is a reasonable method to study the atomization phenomena in supersonic flow. PLIF can detect the distribution of kerosene droplets accurately. Shadowgraph can visualize the wave structure. Higher jet-to-freestream dynamic pressure initiates higher penetration height and the jet column will be easier to breakup and atomize, but it also induces stronger shock waves and aggravate total pressure lost. Three-dimensional, unsteady surface wave plays an important role in making the jet break up and atomize. Higher jet-to-freestream dynamic pressure will accelerate the development of surface wave and enlarge the amplitude of surface wave, while lower jet-to-freestream ratio will inhibit the development of surface wave.

  12. Off-Body Boundary-Layer Measurement Techniques Development for Supersonic Low-Disturbance Flows

    Science.gov (United States)

    Owens, Lewis R.; Kegerise, Michael A.; Wilkinson, Stephen P.

    2011-01-01

    Investigations were performed to develop accurate boundary-layer measurement techniques in a Mach 3.5 laminar boundary layer on a 7 half-angle cone at 0 angle of attack. A discussion of the measurement challenges is presented as well as how each was addressed. A computational study was performed to minimize the probe aerodynamic interference effects resulting in improved pitot and hot-wire probe designs. Probe calibration and positioning processes were also developed with the goal of reducing the measurement uncertainties from 10% levels to less than 5% levels. Efforts were made to define the experimental boundary conditions for the cone flow so comparisons could be made with a set of companion computational simulations. The development status of the mean and dynamic boundary-layer flow measurements for a nominally sharp cone in a low-disturbance supersonic flow is presented.

  13. Study of Interaction between Supersonic Flow and Rods Surrounded by Porous Cavity

    Institute of Scientific and Technical Information of China (English)

    Minoru YAGA; Kenji YAMAMOTO; Piotr DOERFFER; Kenyu OYAKAWA

    2006-01-01

    In this paper,some preliminary calculations and the experiments were performed to figure out the flow field,in which some rods were normally inserted into the main flow surrounded by a porous cavity.As a result,it is found that the starting shock wave severely interacts with the rods,the bow shock wave,its reflections,and the porous wall,which are numerically well predicted at some conditions.Moreover,inserting the rods makes the pressure on the upper wall in the porous region increase when the main flow in the porous region is completely supersonic.The calculations also suggest that three rods cause the widest suction area.

  14. Effect of atomization gas pressure variation on gas flow field in supersonic gas atomization

    Institute of Scientific and Technical Information of China (English)

    2009-01-01

    In this paper, a computational fluid flow model was adopted to investigate the effect of varying atomization gas pressure (P0) on the gas flow field in supersonic gas atomization. The influence of P0 on static pressure and velocity magnitude of the central axis of the flow field was also examined. The numerical results indicate that the maximum gas velocity within the gas field increases with increasing P0. The aspiration pressure (ΔP) is found to decrease as P0 increases at a lower atomization gas pressure. However, at a higher atomization gas pressure increasing P0 causes the opposite: the higher atomization gas pressure, the higher aspiration pressure. The alternation of ΔP is caused by the variations of stagnation point pressure and location of Mach disk, while hardly by the location of stagnation point. A radical pressure gradient is formed along the tip of the delivery tube and increases as P0 increases.

  15. Continuous-Wave Cavity Ring-Down Spectroscopy in a Pulsed Uniform Supersonic Flow

    Science.gov (United States)

    Thawoos, Shameemah; Suas-David, Nicolas; Suits, Arthur

    2017-06-01

    We introduce a new approach that couples a pulsed uniform supersonic flow with high sensitivity continuous wave cavity ringdown spectroscopy (UF-CRDS) operated in the near infrared (NIR). This combination is related to the CRESU technique developed in France and used for many years to study reaction kinetics at low temperature, and to the microwave based chirped-pulse uniform supersonic flow spectrometer (CPUF) developed in our group which has successfully demonstrated the use of pulsed uniform supersonic flow to probe reaction dynamics at temperatures as low as 22 K. CRDS operated with NIR permits access to the first overtones of C-H and O-H stretching/bending which, in combination with its extraordinary sensitivity opens new experiments complementary to the CPUF technique. The UF-CRDS apparatus (Figure) utilizes the pulsed uniform flow produced by means of a piezo-electric stack valve in combination with a Laval nozzle. At present, two machined aluminum Laval nozzles designed for carrier gases Ar and He generate flows with a temperature of approximately 25 K and pressure around 0.15 mbar. This flow is probed by an external cavity diode laser in the NIR (1280-1380 nm). Laval nozzles designed using a newly developed MATLAB-based program will be used in the future. A detailed illustration of the novel UF-CRDS instrumentation and its performance will be presented along with future directions and applications. I. Sims, J. L. Queffelec, A. Defrance, C. Rebrion-Rowe, D. Travers, P. Bocherel, B. Rowe, I. W. Smith, J. Chem. Phys. 100, 4229-4241, (1994). C. Abeysekera, B. Joalland, N. Ariyasingha, L. N. Zack, I. R. Sims, R. W. Field, A. G. Suits, J. Phys. Chem. Lett. 6, 1599-1604, (2015). N. Suas-David, T. Vanfleteren, T. Foldes, S. Kassi, R. Georges, M. Herman, J. Phys. Chem.A, 119, 10022-10034, (2015). C. Abeysekera, B. Joalland, Y. Shi, A. Kamasah, J. M. Oldham, A. G. Suits, Rev. Sci. Instrum. 85, 116107, (2014).

  16. Flutter and thermal buckling control for composite laminated panels in supersonic flow

    Science.gov (United States)

    Li, Feng-Ming; Song, Zhi-Guang

    2013-10-01

    Aerothermoelastic analysis for composite laminated panels in supersonic flow is carried out. The flutter and thermal buckling control for the panels are also investigated. In the modeling for the equation of motion, the influences of in-plane thermal load on the transverse bending deflection are taken into account, and the unsteady aerodynamic pressure in supersonic flow is evaluated by the linear piston theory. The governing equation of the structural system is developed applying the Hamilton's principle. In order to study the influences of aerodynamic pressure on the vibration mode shape of the panel, both the assumed mode method (AMM) and the finite element method (FEM) are used to derive the equation of motion. The proportional feedback control method and the linear quadratic regulator (LQR) are used to design the controller. The aeroelastic stability of the structural system is analyzed using the frequency-domain method. The effects of ply angle of the laminated panel on the critical flutter aerodynamic pressure and the critical buckling temperature change are researched. The flutter and thermal buckling control effects using the proportional feedback control and the LQR are compared. An effective method which can suppress the flutter and thermal buckling simultaneously is proposed.

  17. Laser driven supersonic flow over a compressible foam surface on the Nike lasera)

    Science.gov (United States)

    Harding, E. C.; Drake, R. P.; Aglitskiy, Y.; Plewa, T.; Velikovich, A. L.; Gillespie, R. S.; Weaver, J. L.; Visco, A.; Grosskopf, M. J.; Ditmar, J. R.

    2010-05-01

    A laser driven millimeter-scale target was used to generate a supersonic shear layer in an attempt to create a Kelvin-Helmholtz (KH) unstable interface in a high-energy-density (HED) plasma. The KH instability is a fundamental fluid instability that remains unexplored in HED plasmas, which are relevant to the inertial confinement fusion and astrophysical environments. In the experiment presented here the Nike laser [S. P. Obenschain et al., Phys. Plasmas 3, 2098 (1996)] was used to create and drive Al plasma over a rippled foam surface. In response to the supersonic Al flow (Mach=2.6±1.1) shocks should form in the Al flow near the perturbations. The experimental data were used to infer the existence and location of these shocks. In addition, the interface perturbations show growth that has possible contributions from both KH and Richtmyer-Meshkov instabilities. Since compressible shear layers exhibit smaller growth, it is important to use the KH growth rate derived from the compressible dispersion relation.

  18. Three-Dimensional Inviscid Flow About Supersonic Blunt Cones at Angle of Attack - III: Coupled Subsonic and Supersonic Programs for Inviscid Three-Dimensional Flow

    Energy Technology Data Exchange (ETDEWEB)

    Abbett, M. J.; Fort, R.

    1968-09-01

    The three-dimensional ideal gas flow in the shock layer of a blunted supersonic cone at an angle of attack is calculated using two asymptotic solutions. The first solution calculates the steady state flow in the subsonic nose region by obtaining a time-dependent solution of the hyperbolic equations using numerical techniques. Internal, nonboundary points are calculated using a Lax-Wendroff numerical type technique. Boundary points, shock and body surface, are computed using a time-dependent method of characteristics. When a steady state solution is reached the flow properties on a surface of constant {theta}, (where the Mach number is everywhere > 1) are used for initial data for the afterbody solution. The afterbody solution, using polar coordinates (r, {theta}, {phi}) assumes at r{sub 0} an arbitrary set of initial conditions provided by the nose region solution and computes the downstream flow as a function of {theta}, {phi}, and r until an asymptotic state independent of r develops. The interior mesh points are again calculated using a Lax- Wendroff type technique and the boundary points by a method of characteristics. This report covers the coupling of the time-dependent and radius (r) dependent solutions. Instructions are given for the operation of the resulting Fortran code. The type of input data required is detailed and sample output is provided. Output data is given in two sets of coordinates. One is wind orientated; the other set is given in body orientated coordinates; The analytical transformation from one coordinate system to the other is given.

  19. THEORETIC AND EXPERIMENTAL DETERMINATION OF THE FLOW RESISTANCE COEFFICIENT AT GASEOUS MEDIUM FLOW INTO AND OUT OF THE PNEUMATIC COUPLING

    Directory of Open Access Journals (Sweden)

    Matej URBANSKÝ

    2014-12-01

    Full Text Available In order to continuous tuning of the torsional oscillating mechanical system during its operation, we are making use of application of the pneumatic flexible shaft couplings, developed by us. By the gaseous medium pressure change in pneumatic couplings we can change its torsional stiffness and thereby the dynamics of whole system too. In term of dynamics is necessary to know the transitional effects of mechanical system, which are arising at its continuous tuning. For the numerical computation of these transitional effects it is necessary to know the values of flow resistance coefficients at gaseous medium flow into the compression space of pneumatic coupling from the pressure tank and out of compression space into the atmosphere. For that reason presents this paper theoretic and experimental procedure of given coefficients determination.

  20. Energy and materials flows in the production of liquid and gaseous oxygen

    Energy Technology Data Exchange (ETDEWEB)

    Shen, S.; Wolsky, A.M.

    1980-08-01

    Liquid and gaseous oxygen is produced in an energy-intensive air separation processo that also generates nitrogen. More than 65% of the cost of oxygen is attributable to energy costs. Energy use and materials flows are analyzed for various air separation methods. Effective approaches to energy and material conservation in air separation plants include efficient removal of contaminants (carbon dioxide and water), centralization of air products user-industries so that large air separation plants are cost-effective and the energy use in transportation is minimized, and increased production of nitrogen. Air separation plants can produce more than three times more nitrogen than oxygen, but present markets demand, at most, only 1.5 times more. Full utlization of liquid and gaseous nitrogen should be encouraged, so that the wasted separation energy is minimized. There are potential markets for nitrogen in, for example, cryogenic separation of metallic and plastic wastes, cryogenic particle size reduction, and production of ammonia for fertilizer.

  1. Creeping gaseous flows through elastic tube and annulus micro-configurations

    Science.gov (United States)

    Elbaz, Shai; Jacob, Hila; Gat, Amir

    2016-11-01

    Gaseous flows in elastic micro-configurations is relevant to biological systems (e.g. alveolar ducts in the lungs) as well as to applications such as gas actuated soft micro-robots. We here examine the effect of low-Mach-number compressibility on creeping gaseous axial flows through linearly elastic tube and annulus micro-configurations. For steady flows, the leading-order effects of elasticity on the pressure distribution and mass-flux are obtained. For transient flow in a tube with small deformations, elastic effects are shown to be negligible in leading order due to compressibility. We then examine transient flows in annular configurations where the deformation is significant compared with the gap between the inner and outer cylinders defining the annulus. Both compressibility and elasticity are obtained as dominant terms interacting with viscosity. For a sudden flux impulse, the governing non-linear leading order diffusion equation is initially approximated by a porous-medium-equation of order 2.5 for the pressure square. However, as the fluid expand and the pressure decreases, the governing equation degenerates to a porous-medium-equation of order 2 for the pressure.

  2. Development of a background-oriented schlieren technique with telecentric lenses for supersonic flow

    Science.gov (United States)

    Cozzi, F.; Göttlich, E.; Angelucci, L.; Dossena, V.; Guardone, A.

    2017-01-01

    Background oriented schlieren (BOS) is a quantitative optical technique which exploits light deflection occurring in non-homogeneous transparent media. It allows to indirectly measure the density gradients by analysing the apparent displacement of features of a background pattern when imaged through the investigated flow. Thanks to its simple set-up and to the consolidated data reduction technique based on cross-correlation algorithms the BOS technique has progressively attracted the interest of the researchers. In this work a BOS system using a telecentric lens system has been set up in order to improve measurement accuracy and to avoid 3D effects arising from using conventional entocentric lenses. The design of the telecentric lens system is reported along with an analysis of its performance in term of spatial resolution. Some preliminary tests on a supersonic flows are also reported.

  3. A new Lagrangian method for three-dimensional steady supersonic flows

    Science.gov (United States)

    Loh, Ching-Yuen; Liou, Meng-Sing

    1993-01-01

    In this report, the new Lagrangian method introduced by Loh and Hui is extended for three-dimensional, steady supersonic flow computation. The derivation of the conservation form and the solution of the local Riemann solver using the Godunov and the high-resolution TVD (total variation diminished) scheme is presented. This new approach is accurate and robust, capable of handling complicated geometry and interactions between discontinuous waves. Test problems show that the extended Lagrangian method retains all the advantages of the two-dimensional method (e.g., crisp resolution of a slip-surface (contact discontinuity) and automatic grid generation). In this report, we also suggest a novel three dimensional Riemann problem in which interesting and intricate flow features are present.

  4. Effect of Mach number on the efficiency of microwave energy deposition in supersonic flow

    Science.gov (United States)

    Lashkov, V. A.; Karpenko, A. G.; Khoronzhuk, R. S.; Mashek, I. Ch.

    2016-05-01

    The article is devoted to experimental and numerical studies of the efficiency of microwave energy deposition into a supersonic flow around the blunt cylinder at different Mach numbers. Identical conditions for energy deposition have been kept in the experiments, thus allowing to evaluate the pure effect of varying Mach number on the pressure drop. Euler equations are solved numerically to model the corresponding unsteady flow compressed gas. The results of numerical simulations are compared to the data obtained from the physical experiments. It is shown that the momentum, which the body receives during interaction of the gas domain modified by microwave discharge with a shock layer before the body, increases almost linearly with rising of Mach number and the efficiency of energy deposition also rises.

  5. The influence of boundary layers on supersonic inlet flow unstart induced by mass injection

    Science.gov (United States)

    Do, Hyungrok; Im, Seong-Kyun; Mungal, M. Godfrey; Cappelli, Mark A.

    2011-09-01

    A transverse jet is injected into a supersonic model inlet flow to induce unstart. Planar laser Rayleigh scattering from condensed CO2 particles is used to visualize flow dynamics during the unstart process, while in some cases, wall pressure traces are simultaneously recorded. Studies conducted over a range of inlet configurations reveal that the presence of turbulent wall boundary layers strongly affect the unstart dynamics. It is found that relatively thick turbulent boundary layers in asymmetric wall boundary layer conditions prompt the formation of unstart shocks; in symmetric boundary conditions lead to the propagation of pseudo-shocks; and in both cases facilitate fast inlet unstart, when compared with thin, laminar boundary layers. Incident shockwaves and associated reflections are found to affect the speed of pressure disturbances. These disturbances, which induce boundary layer separation, are found to precede the formation of unstart shocks. The results confirm the importance of and need to better understand shock-boundary layer interactions in inlet unstart dynamics.

  6. Numerical Simulations of Morphology, Flow Structures and Forces for a Sonic Jet Exhausting in Supersonic Crossflow

    Directory of Open Access Journals (Sweden)

    S.B.H Shah

    2012-01-01

    Full Text Available A numerical study is performed for a sonic jet issuing from a blunted cone to provide possible directional control in supersonic crossflow by solving the unsteady Reynolds-averaged Navier-Stokes (RANS equations with the twoequation k −ω turbulence model. Results are presented in the form of static aerodynamic coefficients, computed at a free stream Mach number 4.0, with varying pressure ratios, incidence angle and keeping zero yaw and roll angles. The morphology and flow structure for the jet exhausting in crossflow at various pressure ratios is described in detail. The Flight control of the projectile can be accomplished by taking advantage of a complex shock-boundary layer interaction produced by jet interacting with the oncoming crossflow by altering pressure distribution in vicinity of the jet, a net increase in the net force can be utilized for maneuvering of vehicle and possible flight control. Computed static aerodynamic coefficients and pressure distribution using CFD analyses is with an accuracy of ± 5% in the supersonic range.

  7. Numerical Investigation of Vortex Generator Flow Control for External-Compression Supersonic Inlets

    Science.gov (United States)

    Baydar, Ezgihan

    Vortex generators (VGs) within external-compression supersonic inlets for Mach 1.6 were investigated to determine their ability to increase total pressure recovery and reduce total pressure distortion. Ramp and vane-type VGs were studied. The geometric factors of interest included height, length, spacing, angle-of-incidence, and positions upstream and downstream of the inlet terminal shock. The flow through the inlet was simulated numerically through the solution of the steady-state, Reynolds-averaged Navier-Stokes equations on multi-block, structured grids using the Wind-US flow solver. The inlet performance was characterized by the inlet total pressure recovery and the radial and circumferential total pressure distortion indices at the engine face. Previous research of downstream VGs in the low-boom supersonic inlet demonstrated improvement in radial distortion up to 24% while my work on external-compression supersonic inlets improved radial distortion up to 86%, which is significant. The design of experiments and statistical analysis methods were applied to quantify the effect of the geometric factors of VGs and search for optimal VG arrays. From the analysis, VG angle-of-incidence and VG height were the most influential factors in increasing total pressure recovery and reducing distortion. The study on the two-dimensional external-compression inlet determined which passive flow control devices, such as counter-rotating vanes or ramps, reduce high distortion levels and improve the health of the boundary layer, relative to the baseline. Downstream vanes demonstrate up to 21% improvement in boundary layer health and 86% improvement in radial distortion. Upstream vanes demonstrated up to 3% improvement in boundary layer health and 9% improvement in radial distortion. Ramps showed no improvement in boundary layer health and radial distortion. Micro-VGs were preferred for their reduced viscous drag and improvement in total pressure recovery at the AIP. Although

  8. Modernized scheme of thermal ignition and flame stabilization at flow supersonic speeds in channel

    Science.gov (United States)

    Goldfeld, M. A.; Nalivaychenko, D. G.; Starov, A. V.; Timofeev, K. Yu.

    2016-10-01

    For providing fuel ignition at the high supersonic flow velocity original device was developed. Main element of this device in the form of wall slotted channel has to provide the high flow temperature in the area of mixture. Numerical simulation has been performed based on solving the full averaged Navier-Stokes equations, supplemented k-ɛ turbulence model. The experiments were carried out in the hotshot wind tunnel IT-302M at the mode of the attached pipe. The flow parameters at the model entrance were following: M = 2 - 5.8, p0 = 12 - 390bar, T0 = 1170 - 2930K at equivalence ratio of hydrogen from 0.6 to 1.1. Self-ignition of the hydrogen in the slotted channel has occurred at total flow temperature of 2250K at the combustor entrance. The combustion process is extended to the entire channel of the combustor. When the facility worked with decreasing parameters of the flow, combustion continued until drop of the static temperature of about 230K at the entrance of the combustor.

  9. A Numerical Analysis Of Gaseous Flow in the Entrance Region of Micro-channels

    Directory of Open Access Journals (Sweden)

    Sampad Gobinda Das

    2010-06-01

    Full Text Available Fluid flow in micro-channels is rapidly emerging as a major area of research, due to its wide area of applications invarious forms in industries. Although substantial work has been carried out xperimentally, numerically as well as analytically on this area, still the reported results show wide variation from one another. In the present work an attempt has been made to analyze gaseous flow in two dimensional micro-channels by using a numerical scheme.The momentum equation has been converted into stream function vorticity form and a finite difference technique has been used. Both slip and no slip boundary conditions have been applied and nitrogen and helium have been considered as representative ideal gases. The numerical scheme has been validated and the results have shown theimportance of Knudsen number apart from Reynolds number, in the gaseous flow during its hydro dynamically developing stage. The present work has carried out a comparative study based on the code developed, between nitrogen and helium, one of them being a monatomic gas and the other diatomic. Also a non dimensional analysis has been presented.

  10. A finite difference method for predicting supersonic turbulent boundary layer flows with tangential slot injection

    Science.gov (United States)

    Miner, E. W.; Lewis, C. H.

    1972-01-01

    An implicit finite difference method has been applied to tangential slot injection into supersonic turbulent boundary layer flows. In addition, the effects induced by the interaction between the boundary layer displacement thickness and the external pressure field are considered. In the present method, three different eddy viscosity models have been used to specify the turbulent momentum exchange. One model depends on the species concentration profile and the species conservation equation has been included in the system of governing partial differential equations. Results are compared with experimental data at stream Mach numbers of 2.4 and 6.0 and with results of another finite difference method. Good agreement was generally obtained for the reduction of wall skin friction with slot injection and with experimental Mach number and pitot pressure profiles. Calculations with the effects of pressure interaction included showed these effects to be smaller than effects of changing eddy viscosity models.

  11. Simulation of Supersonic Flow in an Ejector Diffuser Using the JPVM

    Directory of Open Access Journals (Sweden)

    Carlos Couder-Castañeda

    2009-01-01

    creating and holding a vacuum system. The goal of this job is to develop an object oriented parallel numerical code to investigate the unsteady behavior of the supersonic flow in the ejector diffuser to have an efficient computational tool that allows modeling different diffuser designs. The first step is the construction of a proper transformation of the solution space to generate a computational regular space to apply an explicit scheme. The second step, consists in developing the numerical code with an-object-oriented parallel methodology. Finally, the results obtained about the flux are satisfactory compared with the physical sensors, and the parallel paradigm used not only reduces the computational time but also shows a better maintainability, reusability, and extensibility accuracy of the code.

  12. Numerical study of the effect of an embedded surface-heat source on the separation bubble of supersonic flow

    Science.gov (United States)

    Degani, D.

    1983-01-01

    A numerical study of the conjugated problem of a separated supersonic flow field and a conductive solid wall with an embedded heat source is presented. Implicit finite-difference schemes were used to solve the two-dimensional time-dependent compressible Navier-Stokes equations and the time-dependent heat-conduction equation for the solid in both general coordinate systems. A detailed comparison between the thin-layer and Navier-Stokes models was made for steady and unsteady supersonic flow and showed insignificant differences. Steady-state and transient cases were computed and the results show that a temperature pulse at the solid-fluid interface can be used to detect the flow direction near the wall in the vicinity of separation without significant distortion of the flow field.

  13. Supersonic flow about cone eith ijection of gas through its surface described by power law

    Science.gov (United States)

    Antonov, A. M.; Zakrevskiy, V. A.

    1986-01-01

    The influence of intensive mass transfer on the supersonic flow of gas about a cone of finite length is investigated. The mathematical model describing the interaction of the primary flow and the transverse flow formed by injection is the boundary problem for a system of equations presented with boundary conditions on the cone and on the contact discontinuity. It is found that the contact surface is nonrectilinear when the injected gas is described by a power law and that the thickness of the layer coming in contact with the cone increases as the intensity of the injection becomes higher. The distribution of the pressure coefficient along a finite cone is calculated as a function of the parameter(s) associated with the injection flow rate, and the Mach number of the oncoming stream. It is found that the pressure coefficient drops off along the generatrix of a cone for all velocities of injection and oncoming stream when the injection is distributed. As the injection intensity increases, the pressure coefficient on the surface increases.

  14. Three-dimensional supersonic flow around double compression ramp with finite span

    Science.gov (United States)

    Lee, H. S.; Lee, J. H.; Park, G.; Park, S. H.; Byun, Y. H.

    2017-01-01

    Three-dimensional flows of Mach number 3 around a double-compression ramp with finite span have been investigated numerically. Shadowgraph visualisation images obtained in a supersonic wind tunnel are used for comparison. A three-dimensional Reynolds-averaged Navier-Stokes solver was used to obtain steady numerical solutions. Two-dimensional numerical results are also compared. Four different cases were studied: two different second ramp angles of 30° and 45° in configurations with and without sidewalls, respectively. Results showed that there is a leakage of mass and momentum fluxes heading outwards in the spanwise direction for three-dimensional cases without sidewalls. The leakage changed the flow characteristics of the shock-induced boundary layer and resulted in the discrepancy between the experimental data and two-dimensional numerical results. It is found that suppressing the flow leakage by attaching the sidewalls enhances the two-dimensionality of the experimental data for the double-compression ramp flow.

  15. Analytical models for flow control in subsonic and supersonic diffusing flow paths using steady blowing and suction

    Science.gov (United States)

    Sarimurat, Mehmet Nasir

    suction at a given location that is required to hold the shock at a given area ratio as the back pressure is varied. The formulation is based on classical inviscid- and compressible-flow theories for normal shock waves and flow transpiration in converging/diverging flow passages. The theory shows that, for the case where there is a shock wave inside a diverging section with supersonic inlet, as the back pressure is increased, the shock can be held stationary if either flow suction is applied behind the shock or flow blowing is applied in front of the shock. For the case of blowing, the amount of flow blowing required to fix the shock location decreases with both increasing total pressure and total temperature of the blown flow. Applications of this quasi-1D theory are demonstrated for 2D supersonic nozzles and supersonic sections of NASA Rotor-37 and NASA UEET R2 rotors taken at the span station 10% from tip. Excellent agreement between the theory and CFD is observed. For the NASA Rotor-37 and NASA UEET R2 rotor cascade sections studied, if suction behind the shock is applied to fix the shock location inside the passage as the back pressure is increased 3-4% from the design point back pressure, the amount of required flow removal is on the order of 3.5% of the main flow. For the same case if flow blowing is applied in front of the shock, the amount of the flow that is needed to be blown to fix the shock location is a function of the stagnation conditions of the blown flow. When the total pressure of the blown flow is taken to be 1.5 times that of the local flow and the total temperature to be 1.3 times that of the local flow the amount of the flow needed to be blown is on the order of 1% of the main flow.

  16. AN EXPERIMENTAL EVALUATION OF TRANSIENT FLOWS IN A SUPERSONIC GUN TUNNEL

    Directory of Open Access Journals (Sweden)

    Al Al-Falahi Amir

    2012-12-01

    Full Text Available An experimental study has been performed to investigate transient flows in a supersonic gun tunnel. The experimental work was performed using a short duration high speed flow test facility at the Universiti Tenaga Nasional (UNITEN. A physical description of the facility along with the principles of operation is provided. The pressure history of the flow process was captured using a fast response pressure transducer at three stations located at the end of the facility. Experimental measurements of shock strength, peak pressure and shock wave speed change of Air-Air as a driver/driven gas are then presented and compared with a further set of experimental measurements using the gas combination of Helium-Air. The shock wave speed was measured experimentally with a two pressure transducers technique. The results showed that the existence of the piston has a very significant influence on both the moving shock wave and peak pressure value achieved. The results provide a very good estimate for the above-mentioned parameters obtained after diaphragm rupture, and also provide a better understanding of the parameters that affect the performance of the facility.

  17. Production of high-beta magnetised plasmas by colliding supersonic flows from inverse wire arrays

    Science.gov (United States)

    Hare, Jack; Suttle, Lee; Lebedev, Sergey; Bennett, Matthew; Burdiak, Guy; Clayson, Thomas; Suzuki-Vidal, Francisco; Swadling, George; Patankar, Siddharth; Robinson, Timothy; Stuart, Nicholas; Smith, Roland; Yang, Qingguo; Wu, Jian; Rozmus, Wojciech

    2015-11-01

    HEDP often exhibit a high plasma β and an electron Hall parameter greater than one. This results in a complex interplay between the transport of heat and magnetic fields, relevant to the Magnetised Liner Inertial Fusion (MagLIF) concept. We can produce such plasmas by colliding two supersonic quasi-planar flows from two adjacent inverse wire arrays made from carbon. The standing shock formed by the collision heats and compresses the plasma. The plasma flows advect magnetic fields which are perpendicular to the flow direction. Depending on the experimental set up, this can result in either flux compression or reconnection in the interaction region. The experiments are conducted on MAGPIE (1.4 MA, 250 ns current pulse). The formed shock is stable over long timescales (~100 ns), and the electron temperature (100 eV) is close to the ion temperature (500 eV), measured by spatially resolved Thomson scattering. Magnetic fields above 5 T is observed using a Faraday rotation diagnostic, and an electron density of around 5x1017 cm-3 is measured by interferometry.

  18. Overexpanded Performance of Conical Nozzles with Area Ratios of 6 and 9 With and Without Supersonic External Flow

    Science.gov (United States)

    Musial, Norman T.; Ward, James J.

    1959-01-01

    An investigation of the thrust characteristics and internal pressure distributions of two convergent-divergent 15 deg. half-angle exhaust nozzles having area ratios of 6 and 9 was made in the NASA Lewis 10- by 10-foot supersonic wind tunnel. The tests were conducted at free-stream Mach numbers of 0, 2.0, 2.5, 3.0, and 3.5 over a range of nozzle pressure ratios from 3 to 105. Attempts were made to induce separation of the overexpanded nozzle flow using secondary airflow and a wedge. Nozzle flow expansion under all free-stream conditions followed one-dimensional theory until separation from the nozzle wall occurred. In quiescent air the nozzle flow expanded to a pressure approximately one-half the base pressure before separation. When the nozzles were tested with supersonic external flow at the same effective pressure ratios, the nozzle flow separated with negligible expansion below the base pressure. The effect of a supersonic stream on internal nozzle flow separation characteristics was well defined only at a free-stream Mach number of 2.0. Thrust data at supersonic free-stream conditions indicate that only a small percentage of the ideal nozzle thrust will be available at nozzle pressure ratios below design. However, the overexpanded primary nozzle thrust loss was decreased by injecting large quantities of secondary air near the nozzle exit. In most cases no net gain in thrust resulted from secondary-air injection when the nozzle thrust was compared with the ideal thrust of both the primary and secondary airflows.

  19. On supersonic combustion

    Institute of Scientific and Technical Information of China (English)

    袁生学

    1999-01-01

    Some basic concepts and features of supersonic combustion are explained from the view point of macroscopic aerodynamics. Two kinds of interpretations of supersonic combustion are proposed. The difference between supersonic combustion and subsonic combustion is discussed, and the mechanism of supersonic combustion propagation and the limitation of heat addition in supersonic flow are pointed out. The results of the calculation of deflagration in supersonic flow show that the entropy increment and the total pressure loss of the combustion products may decrease with the increase of combustion velocity. It is also demonstrated that the oblique detonation wave angle may not be controlled by the wedge angle under weak underdriven solution conditions and be determined only by combustion velocity. Therefore, the weak underdriven solution may become self-sustaining oblique detonation waves with a constant wave angle.

  20. Application of Tomo-PIV in a large-scale supersonic jet flow facility

    Science.gov (United States)

    Wernet, Mark P.

    2016-09-01

    Particle imaging velocimetry (PIV) has been used extensively at NASA GRC over the last 15 years to build a benchmark data set of hot and cold jet flow measurements in an effort to understand acoustic noise sources in high-speed jets. Identifying the noise sources in high-speed jets is critical for ultimately modifying the nozzle hardware design/operation and therefore reducing the jet noise. Tomographic PIV (Tomo-PIV) is an innovative approach for acquiring and extracting velocity information across extended volumes of a flow field, enabling the computation of additional fluid mechanical properties not typically available using traditional PIV techniques. The objective of this work was to develop and implement the Tomo-PIV measurement capability and apply it in a large-scale outdoor test facility, where seeding multiple flow streams and operating in the presence of daylight presents formidable challenges. The newly developed Tomo-PIV measurement capability was applied in both a subsonic M 0.9 flow and an under-expanded M 1.4 heated jet flow field. Measurements were also obtained using traditional two-component (2C) PIV and stereo PIV in the M 0.9 flow field for comparison and validation of the Tomo-PIV results. In the case of the M 1.4 flow, only the 2C PIV was applied to allow a comparison with the Tomo-PIV measurement. The Tomo-PIV fields-of-view covered 180 × 180 × 10 mm, and the reconstruction domains were 3500 × 3500 × 200 voxels. These Tomo-PIV measurements yielded all three components of vorticity across entire planes for the first time in heated supersonic jet flows and provided the first full 3D reconstruction of the Mach disk and oblique shock intersections inside of the barrel shocks. Measuring all three components of vorticity across multiple planes in the flow, potentially reduces the number of measurement configurations (streamwise and cross-stream PIV) required to fully characterize the mixing-enhanced nozzle flows routinely studied in

  1. Comparison of calculated and measured heat transfer coefficients for transonic and supersonic boundary-layer flows

    Energy Technology Data Exchange (ETDEWEB)

    Huerst, C.; Schulz, A.; Wittig, S. [Univ. Karlsruhe (Germany). Lehrstuhl und Inst. fuer Thermische Stroemungsmaschinen

    1995-04-01

    The present study compares measured and computed heat transfer coefficients for high-speed boundary layer nozzle flows under engine Reynolds number conditions (U{sub {infinity}} = 230 {divided_by} 880 m/s, Re* = 0.37 {divided_by} 1.07 {times} 10{sup 6}). Experimental data have been obtained by heat transfer measurements in a two-dimensional, nonsymmetric, convergent-divergent nozzle. The nozzle wall is convectively cooled using water passages. The coolant heat transfer data and nozzle surface temperatures are used as boundary conditions for a three-dimensional finite-element code, which is employed to calculate the temperature distribution inside the nozzle wall. Heat transfer coefficients along the hot gas nozzle wall are derived from the temperature gradients normal to the surface. The results are compared with numerical heat transfer predictions using the low-Reynolds-number {kappa}-{epsilon} turbulence model by Lam and Bremhorst. Influence of compressibility in the transport equations for the turbulence properties is taken into account by using the local averaged density. The results confirm that this simplification leads to good results for transonic and low supersonic flows.

  2. Effect of Off-Body Laser Discharge on Drag Reduction of Hemisphere Cylinder in Supersonic Flow

    Science.gov (United States)

    Kianvashrad, Nadia; Knight, Doyle; Wilkinson, Stephen P.; Chou, Amanda; Horne, Robert A.; Herring, Gregory C.; Beeler, George B.; Jangda, Moazzam

    2017-01-01

    The interaction of an off-body laser discharge with a hemisphere cylinder in supersonic flow is investigated. The objectives are 1) experimental determination of the drag reduction and energetic efficiency of the laser discharge, and 2) assessment of the capability for accurate simulation of the interaction. The combined computational and experimental study comprises two phases. In the first phase, laser discharge in quiescent air was examined. The temporal behavior of the shock wave formed by the laser discharge was compared between experiment and simulation and good agreement is observed. In the second phase, the interaction of the laser discharge with a hemisphere cylinder was investigated numerically. Details of the pressure drag reduction and the physics of the interaction of the heated region with the bow shock are included. The drag reduction due to this interaction persisted for about five characteristic times where one characteristic time represents the time for the flow to move a distance equal to the hemisphere radius. The energetic efficiency of laser discharge for the case with 50 mJ energy absorbed by the gas is calculated as 3.22.

  3. Quantified infrared imaging of ignition and combustion in a supersonic flow

    Science.gov (United States)

    Ombrello, Timothy; Blunck, David L.; Resor, Michael

    2016-09-01

    The utility of quantified infrared radiation imaging was evaluated through interrogating ignition and burning processes within a cavity-based flameholder in supersonic flows. Two ignition techniques, spark discharge and pulse detonation, along with quasi-steady cavity burning were used to assess the sensitivities of measurements of radiation intensities in the infrared. The shedding of ignition kernels from the spark discharge was imaged, showing that sufficient signal-to-noise ratios can be achieved even with weak radiation emission levels. The ignition events using a pulse detonator were captured with time-resolved measurements of the plume evolution, including the barrel shock, Mach disk, and shock diamonds. Radiation emissions from subsequent firings of the pulse detonator increased, indicating that heat loss to the tube walls occurred in the early pulses. Imaging of the quasi-steady burning within the cavity demonstrated that the highest burning flux (visible broadband chemiluminescence) and radiation from hydrocarbons (3.4 µm) do not coincide with each other for the fueling strategy used. Numerical simulations provided insight into the species distributions that caused the infrared emissions. Overall, infrared radiation measurements have been shown to be feasible through combustor windows in the harsh combustion environments that were interrogated, and offer a new avenue for rapid and quantitative measurements of reactive flow.

  4. Impact of surface proximity on flow and acoustics of a rectangular supersonic jet

    Science.gov (United States)

    Gutmark, Ephraim; Baier, Florian; Mora, Pablo; Kailsanath, Kailas; Viswanath, Kamal; Johnson, Ryan

    2016-11-01

    Advances in jet technology have pushed towards faster aircraft, leading to more streamlined designs and configurations, pushing engines closer to the aircraft frame. This creates additional noise sources stemming from interactions between the jet flow and surfaces on the aircraft body, and interaction between the jet and the ground during takeoff and landing. The paper studies the impact of the presence of a flat plate on the flow structures and acoustics in an M =1.5 (NPR =3.67) supersonic jet exhausting from a rectangular C-D nozzle. Comparisons are drawn between baseline cases without a plate and varying nozzle-plate distance at NPRs from 2.5 to 4.5, and temperature ratios of up to 3.0. At the shielded side and sideline of the plate noise is mitigated only when the plate is at the nozzle lip (h =0). Low frequency mixing noise is increased in the downstream direction only for h =0. Screech tones that exist only for low NTR are fully suppressed by the plate at h =0. However, for h>0 the reflection enhances screech at both reflected side and sideline. Low frequency mixing noise is enhanced by the plate at the reflected side at all plate distances, while broad band shock associated noise is reduced only at the sideline for h =0. Increased temperature mitigates the screech tones across all test conditions. The results are compared to a circular nozzle of equivalent diameter with an adjacent plate.

  5. The Calculation of Supersonic Flows with Strong Viscous-Inviscid Interaction Using the Parabolized Navier - Equations

    Science.gov (United States)

    Barnett, Mark

    This investigation is concerned with calculating strong viscous-inviscid interactions in two-dimensional laminar supersonic flows with and without separation. The equations solved are the so-called parabolized Navier-Stokes equations. The streamwise pressure gradient term is written as a combination of a forward and a backward difference to provide a path for upstream propogation of information. Global iteration is employed to repeatedly update the solution from an initial guess until convergence is achieved. Interacting boundary layer theory is discussed in order to provide some essential background information for the development of the present calculation technique. The numerical scheme used is an alternating direction explicit (ADE) procedure which is adapted from the Saul'yev method. This technique is chosen as an alternative to the more difficult to program multigrid strategy used by other investigators and the slower converging Gauss-Seidel method. Separated flows are computed using the ADE method. Only small or moderate separation bubbles are considered. This restriction permits simple approximations to the convective terms in reversed flow regions without introducing severe error since the reversed flow velocities are small. Results are presented for a number of geometries including compression ramps and humps on flat plates with separation. The present results are compared with those obtained by other investigators using the full Navier-Stokes equations and interacting boundary layer theory. Comparisons were found to be qualitatively good. The quantitative comparisons varied, however mesh refinement studies indicated that the parabolized Navier-Stokes solutions tended towards second-order accurate full Navier-Stokes solutions as well as interacting boundary layer solutions for which mesh refinement studies were also executed.

  6. Supersonic Mass Flux Measurements via Tunable Diode Laser Absorption and Non-Uniform Flow Modeling

    Science.gov (United States)

    Chang, Leyen S.; Strand, Christopher L.; Jeffries, Jay B.; Hanson, Ronald K.; Diskin, Glenn S.; Gaffney, Richard L.; Capriotti, Diego P.

    2011-01-01

    Measurements of mass flux are obtained in a vitiated supersonic ground test facility using a sensor based on line-of-sight (LOS) diode laser absorption of water vapor. Mass flux is determined from the product of measured velocity and density. The relative Doppler shift of an absorption transition for beams directed upstream and downstream in the flow is used to measure velocity. Temperature is determined from the ratio of absorption signals of two transitions (lambda(sub 1)=1349 nm and lambda(sub 2)=1341.5 nm) and is coupled with a facility pressure measurement to obtain density. The sensor exploits wavelength-modulation spectroscopy with second-harmonic detection (WMS-2f) for large signal-to-noise ratios and normalization with the 1f signal for rejection of non-absorption related transmission fluctuations. The sensor line-of-sight is translated both vertically and horizontally across the test section for spatially-resolved measurements. Time-resolved measurements of mass flux are used to assess the stability of flow conditions produced by the facility. Measurements of mass flux are within 1.5% of the value obtained using a facility predictive code. The distortion of the WMS lineshape caused by boundary layers along the laser line-of-sight is examined and the subsequent effect on the measured velocity is discussed. A method for correcting measured velocities for flow non-uniformities is introduced and application of this correction brings measured velocities within 4 m/s of the predicted value in a 1630 m/s flow.

  7. (DURIP 10) High Speed Intensified Imaging System For Studies Of Mixing And Combustion In Supersonic Flows And Hydrocarbon Flame Structure Measurements At Elevated Pressures

    Science.gov (United States)

    2016-11-09

    AFRL-AFOSR-VA-TR-2016-0357 (DURIP 10) HIGH-SPEED INTENSIFIED IMAGING SYSTEM FOR STUDIES OF MIXING AND COMBUSTION IN SUPERSONIC FLOWS AND HYDROCARBON...COVERED (From - To) 03 Sep 2010 to 29 Sep 2011 4. TITLE AND SUBTITLE (DURIP 10) HIGH-SPEED INTENSIFIED IMAGING SYSTEM FOR STUDIES OF MIXING AND COMBUSTION ...91125 HIGH SPEED INTENSIFIED IMAGING SYSTEM FOR MIXING AND COMBUSTION IN SUPERSONIC FLOWS AND HYDROCARBON- FLAME STRUCTURE MEASUREMENTS AT

  8. Sound generated by instability waves of supersonic flows. I Two-dimensional mixing layers. II - Axisymmetric jets

    Science.gov (United States)

    Tam, C. K. W.; Burton, D. E.

    1984-01-01

    An investigation is conducted of the phenomenon of sound generation by spatially growing instability waves in high-speed flows. It is pointed out that this process of noise generation is most effective when the flow is supersonic relative to the ambient speed of sound. The inner and outer asymptotic expansions corresponding to an excited instability wave in a two-dimensional mixing layer and its associated acoustic fields are constructed in terms of the inner and outer spatial variables. In matching the solutions, the intermediate matching principle of Van Dyke and Cole is followed. The validity of the theory is tested by applying it to an axisymmetric supersonic jet and comparing the calculated results with experimental measurements. Very favorable agreements are found both in the calculated instability-wave amplitude distribution (the inner solution) and the near pressure field level contours (the outer solution) in each case.

  9. Effects of Varied Shear Correction on the Thermal Vibration of Functionally-Graded Material Shells in an Unsteady Supersonic Flow

    Directory of Open Access Journals (Sweden)

    Chih Chiang Hong

    2017-03-01

    Full Text Available A model is presented for functionally-graded material (FGM, thick, circular cylindrical shells under an unsteady supersonic flow, following first-order shear deformation theory (FSDT with varied shear correction coefficients. Some interesting vibration results of the dynamics are calculated by using the generalized differential quadrature (GDQ method. The varied shear correction coefficients are usually functions of FGM total thickness, power law index, and environment temperature. Two parametric effects of the environmental temperature and FGM power law index on the thermal stress and center deflection are also presented. The novelty of the paper is that the maximum flutter value of the center deflection amplitude can be predicted and occurs at a high frequency of applied heat flux for a supersonic air flow.

  10. A classical flow instability and its connection to gaseous galactic disk hydrodynamics

    CERN Document Server

    Vatistas, G H

    2007-01-01

    Water vortices are known to develop polygon structures inside their cores. The apexes of the polygonal manifestations are the result of satellite vortices attached to the parent vortex. Exploiting the analogy between the shallow water hydraulics and the two-dimensional compressible gas flows we arrive to the following line of reasoning concerning the spiral galactic structure. The backward free surface fore ripples of the advancing pressure disturbance in the hydraulic system should appear as high-density spirals in the gaseous galactic disk. Since the number of galactic arms is equal to the number of satellite eddies in the parent vortex, spiral galaxies with say two arms will possess two nuclei. The last appears to be in complete agreement with the latest observations regarding M 31 and Mrk 315 galaxies. If the present hypothesis is accurate then a closer look at the central regions of multi-tentacle spiral galaxies should also reveal that these have multiple nuclei.

  11. Heat transfer in supersonic dusty-gas flow past a blunt body with inertial particle deposition effect

    Institute of Scientific and Technical Information of China (English)

    2002-01-01

    Heat transfer in a supersonic steady flow of a dilute dusty-gas past a sphere is considered at large and moderate Reynolds numbers. For the regime of inertial particle deposition on the frontal surface of the body, a parametric study of maximum increase in the particle-induced heat flux at the stagnation point is performed over a wide range of the Reynolds number, the particle inertia parameter, the ratio of the phase specific heats, and the body surface temperature.

  12. CFD Analysis of a Supersonic Air Ejector. Part II: Relation between Global Operation and Local Flow Features

    OpenAIRE

    Hemidi, Amel; Henry, François; Leclaire, Sébastien; Seynhaeve, Jean-Marie; Bartosiewicz, Yann

    2009-01-01

    Abstract This paper presents an original CFD analysis of the operation of a supersonic ejector. This study is based on CFD and experimental results obtained in the first part paper [1]. Results clearly demonstrates that a good predictions of the entrainment rate, even over a wide range of operating conditions, do not necessarily mean a good prediction of the local flow features. This issue is shown through the results obtained for two turbulence models, and also raises the problem ...

  13. Uptake of gaseous formaldehyde onto soil surfaces: a coated-wall flow tube study

    Science.gov (United States)

    Li, Guo; Su, Hang; Li, Xin; Meusel, Hannah; Kuhn, Uwe; Pöschl, Ulrich; Shao, Min; Cheng, Yafang

    2015-04-01

    Gaseous formaldehyde (HCHO) is an important intermediate molecule and source of HO2 radicals. However, discrepancies exist between model simulated and observed HCHO concentrations, suggesting missing sources or sinks in the HCHO budget. Multiphase processes on the surface of soil and airborne soil-derived particles have been suggested as an important mechanism for the production/removal of atmospheric trace gases and aerosols. In this work, the uptake of gaseous HCHO on soil surfaces were investigated through coated-wall flow tube experiments with HCHO concentration ranging from 10 to 40 ppbv. The results show that the adsorption of HCHO occurred on soil surfaces, and the uptake coefficient dropped gradually (i.e., by a factor of 5 after 1 hour) as the reactive surface sites were consumed. The HCHO uptake coefficient was found to be affected by the relative humidity (RH), decreasing from (2.4 ± 0.5) × 10-4 at 0% RH to (3.0 ± 0.08) × 10-5 at 70% RH, due to competition of water molecule absorption on the soil surface. A release of HCHO from reacted soil was also detected by applying zero air, suggesting the nature of reversible physical absorption and the existence of an equilibrium at the soil-gas interface. It implies that soil could be either a source or a sink for HCHO, depending on the ambient HCHO concentration. We also develop a Matlab program to calculate the uptake coefficient under laminar flow conditions based on the Cooney-Kim-Davis method.

  14. Cpuf: Chirped-Pulse Microwave Spectroscopy in Pulsed Uniform Supersonic Flows

    Science.gov (United States)

    Suits, Arthur; Abeysekera, Chamara; Zack, Lindsay N.; Joalland, Baptiste; Ariyasingha, Nuwandi M.; Park, Barratt; Field, Robert W.; Sims, Ian

    2015-06-01

    Chirped-pulse Fourier-transform microwave spectroscopy has stimulated a resurgence of interest in rotational spectroscopy owing to the dramatic reduction in spectral acquisition time it enjoys when compared to cavity-based instruments. This suggests that it might be possible to adapt the method to study chemical reaction dynamics and even chemical kinetics using rotational spectroscopy. The great advantage of this would be clear, quantifiable spectroscopic signatures for polyatomic products as well as the possibility to identify and characterize new radical reaction products and transient intermediates. To achieve this, however, several conditions must be met: 1) products must be thermalized at low temperature to maximize the population difference needed to achieve adequate signal levels and to permit product quantification based on the rotational line strength; 2) a large density and volume of reaction products is also needed to achieve adequate signal levels; and 3) for kinetics studies, a uniform density and temperature is needed throughout the course of the reaction. These conditions are all happily met by the uniform supersonic flow produced from a Laval nozzle expansion. In collaboration with the Field group at MIT we have developed a new instrument we term a CPUF (Chirped-pulse/Uniform Flow) spectrometer in which we can study reaction dynamics, photochemistry and kinetics using broadband microwave and millimeter wave spectroscopy as a product probe. We will illustrate the performance of the system with a few examples of photodissociation and reaction dynamics, and also discuss a number of challenges unique to the application of chirped-pulse microwave spectroscopy in the collisional environment of the flow. Future directions and opportunities for application of CPUF will also be explored.

  15. Supersonic shear flows in laser driven high-energy-density plasmas created by the Nike laser

    Science.gov (United States)

    Harding, E. C.; Drake, R. P.; Gillespie, R. S.; Grosskopf, M. J.; Ditmar, J. R.; Aglitskiy, Y.; Weaver, J. L.; Velikovich, A. L.; Plewa, T.

    2008-11-01

    In high-energy-density (HED) plasmas the Kelvin-Helmholtz (KH) instability plays an important role in the evolution of Rayleigh-Taylor (RT) and Richtmyer-Meshkov (RM) unstable interfaces, as well as material interfaces that experience the passage one or multiple oblique shocks. Despite the potentially important role of the KH instability few experiments have been carried out to explore its behavior in the high-energy-density regime. We report on the evolution of a supersonic shear flow that is generated by the release of a high velocity (>100 km/s) aluminum plasma onto a CRF foam (ρ = 0.1 g/cc) surface. In order to seed the Kelvin-Helmholtz (KH) instability various two-dimensional sinusoidal perturbations (λ = 100, 200, and 300 μm with peak-to-valley amplitudes of 10, 20, and 30 μm respectively) have been machined into the foam surface. This experiment was performed using the Nike laser at the Naval Research Laboratory.

  16. Impact of chevron spacing and asymmetric distribution on supersonic jet acoustics and flow

    Science.gov (United States)

    Heeb, N.; Gutmark, E.; Kailasanath, K.

    2016-05-01

    An experimental investigation into the effect of chevron spacing and distribution on supersonic jets was performed. Cross-stream and streamwise particle imaging velocimetry measurements were used to relate flow field modification to sound field changes measured by far-field microphones in the overexpanded, ideally expanded, and underexpanded regimes. Drastic modification of the jet cross-section was achieved by the investigated configurations, with both elliptic and triangular shapes attained downstream. Consequently, screech was nearly eliminated with reductions in the range of 10-25 dB depending on the operating condition. Analysis of the streamwise velocity indicated that both the mean shock spacing and strength were reduced resulting in an increase in the broadband shock associated noise spectral peak frequency and a reduction in the amplitude, respectively. Maximum broadband shock associated noise amplitude reductions were in the 5-7 dB range. Chevron proximity was found to be the primary driver of peak vorticity production, though persistence followed the opposite trend. The integrated streamwise vorticity modulus was found to be correlated with peak large scale turbulent mixing noise reduction, though optimal overall sound pressure level reductions did not necessarily follow due to the shock/fine scale mixing noise sources. Optimal large scale mixing noise reductions were in the 5-6 dB range.

  17. Preliminary Experimental Investigation on MHD Power Generation Using Seeded Supersonic Argon Flow as Working Fluid

    Institute of Scientific and Technical Information of China (English)

    LI Yiwen; LI Yinghong; LU Haoyu; ZHU Tao; ZHANG Bailing; CHEN Feng; ZHAO Xiaohu

    2011-01-01

    This paper presents a preliminary experimental investigation on magnetohydrodynamic (MHD) power generation using seeded supersonic argon flow as working fluid.Helium and argon are used as driver and driven gas respectively in a shock tunnel.Equilibrium contact surface operating mode is used to obtain high temperature gas,and the conductivity is obtained by adding seed K2CO3 powder into the driven section.Under the conditions of nozzle inlet total pressure being 0.32 MPa,total temperature 6 504 K,magnetic field density about 0.5 T and nozzle outlet velocity 1 959 m/s,induction voltage and short-circuit current of the segmentation MHD power generation channel are measured,and the experimental results agree with theoretical calculations; the average conductivity is about 20 S/m calculated from characteristics of voltage and current.When load factor is 0.5,the maximum power density of the MHD power generation channel reaches 4.797 1 MW/m3,and the maximum enthalpy extraction rate is 0.34%.Finally,the principle and method of indirect testing for gas state parameters are derived and analyzed.

  18. Aerodynamic analysis of the aerospaceplane HyPlane in supersonic rarefied flow

    Science.gov (United States)

    Zuppardi, Gennaro; Savino, Raffaele; Russo, Gennaro; Spano'Cuomo, Luca; Petrosino, Eliano

    2016-06-01

    HyPlane is the Italian aerospaceplane proposal targeting, at the same time, both the space tourism and point-to-point intercontinental hypersonic flights. Unlike other aerospaceplane projects, relying on boosters or mother airplanes that bring the vehicle to high altitude, HyPlane will take off and land horizontally from common runways. According to the current project, HyPlane will fly sub-orbital trajectories under high-supersonic/low-hypersonic continuum flow regimes. It can go beyond the von Karman line at 100 km altitude for a short time, then starting the descending leg of the trajectory. Its aerodynamic behavior up to 70 km have already been studied and the results published in previous works. In the present paper some aspects of the aerodynamic behavior of HyPlane have been analyzed at 80, 90 and 100 km. Computer tests, calculating the aerodynamic parameters, have been carried out by a Direct Simulation Monte Carlo code. The effects of the Knudsen, Mach and Reynolds numbers have been evaluated in clean configuration. The effects of the aerodynamic surfaces on the rolling, pitching and yawing moments, and therefore on the capability to control attitude, have been analyzed at 100 km altitude. The aerodynamic behavior has been compared also with that of another aerospaceplane at 100 km both in clean and flapped configuration.

  19. Lattice Boltzmann simulation of separation phenomenon in a binary gaseous flow through a microchannel

    CERN Document Server

    Wang, Liang; Guo, Zhaoli

    2016-01-01

    Gas separation of a binary gaseous mixture is one of characteristic phenomena in the micro-scale flows that differ from the conventional size flows. In this work, the separation in a binary gas mixture flows through a microchannel is investigated by the lattice Boltzmann method with a diffuse-bounce-back (DBB) boundary condition. The separation degree and rate are measured in the He--Ar and Ne--Ar systems for different mole fractions, pressure ratios, and Knudsen numbers. The results show that the separation phenomenon in the He--Ar mixture is more obvious than that in the Ne--Ar mixture at the same mole fraction owing to the larger molecular mass ratio. In addition, the increase in the pressure ratio reduces the difference in the molecular velocities between the two species, and the separation phenomenon becomes weaker. However, the gas separation is enhanced with an increase in the Knudsen number. This is because the resulting rarefaction effect reduces the interactions between the gas molecules of the two ...

  20. Supersonic compressor

    Science.gov (United States)

    Roberts, II, William Byron; Lawlor, Shawn P.; Breidenthal, Robert E.

    2016-04-12

    A supersonic compressor including a rotor to deliver a gas at supersonic conditions to a diffuser. The diffuser includes a plurality of aerodynamic ducts that have converging and diverging portions, for deceleration of gas to subsonic conditions and then for expansion of subsonic gas, to change kinetic energy of the gas to static pressure. The aerodynamic ducts include vortex generating structures for controlling boundary layer, and structures for changing the effective contraction ratio to enable starting even when the aerodynamic ducts are designed for high pressure ratios, and structures for boundary layer control. In an embodiment, aerodynamic ducts are provided having an aspect ratio of in excess of two to one, when viewed in cross-section orthogonal to flow direction at an entrance to the aerodynamic duct.

  1. Control of supersonic axisymmetric base flows using passive splitter plates and pulsed plasma actuators

    Science.gov (United States)

    Reedy, Todd Mitchell

    An experimental investigation evaluating the effects of flow control on the near-wake downstream of a blunt-based axisymmetric body in supersonic flow has been conducted. To better understand and control the physical phenomena that govern these massively separated high-speed flows, this research examined both passive and active flow-control methodologies designed to alter the stability characteristics and structure of the near-wake. The passive control investigation consisted of inserting splitter plates into the recirculation region. The active control technique utilized energy deposition from multiple electric-arc plasma discharges placed around the base. The flow-control authority of both methodologies was evaluated with experimental diagnostics including particle image velocimetry, schlieren photography, surface flow visualization, pressure-sensitive paint, and discrete surface pressure measurements. Using a blowdown-type wind tunnel reconstructed specifically for these studies, baseline axisymmetric experiments without control were conducted for a nominal approach Mach number of 2.5. In addition to traditional base pressure measurements, mean velocity and turbulence quantities were acquired using two-component, planar particle image velocimetry. As a result, substantial insight was gained regarding the time-averaged and instantaneous near-wake flow fields. This dataset will supplement the previous benchmark point-wise laser Doppler velocimetry data of Herrin and Dutton (1994) for comparison with new computational predictive techniques. Next, experiments were conducted to study the effects of passive triangular splitter plates placed in the recirculation region behind a blunt-based axisymmetric body. By dividing the near-wake into 1/2, 1/3, and 1/4 cylindrical regions, the time-averaged base pressure distribution, time-series pressure fluctuations, and presumably the stability characteristics were altered. While the spatial base pressure distribution was

  2. Flow synthesis using gaseous ammonia in a Teflon AF-2400 tube-in-tube reactor: Paal-Knorr pyrrole formation and gas concentration measurement by inline flow titration.

    Science.gov (United States)

    Cranwell, Philippa B; O'Brien, Matthew; Browne, Duncan L; Koos, Peter; Polyzos, Anastasios; Peña-López, Miguel; Ley, Steven V

    2012-08-14

    Using a simple and accessible Teflon AF-2400 based tube-in-tube reactor, a series of pyrroles were synthesised in flow using the Paal-Knorr reaction of 1,4-diketones with gaseous ammonia. An inline flow titration technique allowed measurement of the ammonia concentration and its relationship to residence time and temperature.

  3. Zeroth-order flutter prediction for cantilevered plates in supersonic flow

    CSIR Research Space (South Africa)

    Meijer, M-C

    2015-08-01

    Full Text Available An aeroelastic prediction framework in MATLAB with modularity in the quasi-steady aerodynamic methodology is developed. Local piston theory (LPT) is integrated with quasi-steady methods including shock-expansion theory and the Supersonic Hypersonic...

  4. Effects of fuel injection on mixing and upstream interactions in supersonic flow

    Science.gov (United States)

    Tu, Qiuya

    Scramjet engine performance has been studied experimentally and computationally almost under steady-state conditions. Transients of the airflow and fueling in the scramjet's isolator or combustor create important fluid-dynamic/ combustion interactions. Spark schlieren photography was employed to study the effects of pressure rise in the combustion chamber on the isolator flow at three conditions with isolator entrance Mach number of 1.6, 1.9 and 2.5, covering the range of dual-mode combustion and transition to full scramjet operation. Heat release through combustion in the model scramjet was simulated by incrementally blocking the flow exit until upstream-interaction was induced and a shock train formed in the isolator. Theoretical predictions of the pressure rise in the isolator under separated flow conditions were calculated, which agreed well with the experimental data. The prediction is sensitive to the accurate modeling of the isolator inlet conditions and the correct selection of wall friction coefficient. Gaseous helium and argon have been transversely injected into a Mach 1.6 airflow simulating a light and a heavy fuel injection behind a thin triangular pylon placed upstream, in the isolator, which has a negligible impact on pressure losses. Planar laser-induced fluorescence (PLIF) was used to observe the penetration and mixing in the test section at three cross-sections including the recirculation region and beyond. Results were compared to the no-pylon cases, which showed the presence of the pylon resulted in improving both penetration and spreading of the jet. Simulation for shock wave/ boundary-layer interaction was conducted in Fluent for case of M=1.9 at 60% blockage by using k-ε RNG model with two different near wall treatments. In both cases, the shock ran out of isolator before the computation converged, this is different from experimental results. Proper actual wall friction force may have a very important effect on the computation, which needs

  5. Aeroelastic analysis of circular cylindrical and truncated conical shells subjected to a supersonic flow

    Science.gov (United States)

    Sabri, Farhad

    Shells of revolution, particularly cylindrical and conical shells, are one of the basic structural elements in the aerospace structures. With the advent of high speed aircrafts, these shells can show dynamic instabilities when they are exposed to a supersonic flow. Therefore, aeroelastic analysis of these elements is one of the primary design criteria which aeronautical engineers are dealing with. This analysis can be done with the help of finite element method (FEM) coupled with the computational fluid dynamic (CFD) or by experimental methods but it is time consuming and very expensive. The purpose of this dissertation is to develop such a numerical tool to do aeroelastic analysis in a fast and precise way. Meanwhile during the design stage, where the different configurations, loading and boundary conditions may need to be analyzed, this numerical method can be used very easily with the high order of reliability. In this study structural modeling is a combination of linear Sanders thin shell theory and classical finite element method. Based on this hybrid finite element method, the shell displacements are found from the exact solutions of shell theory rather than approximating by polynomial function done in traditional finite element method. This leads to a precise and fast convergence. Supersonic aerodynamic modeling is done based on the piston theory and modified piston theory with the shell curvature term. The stress stiffening due to lateral pressure and axial compression are also taken into accounts. Fluid-structure interaction in the presence of inside quiescent fluid is modeled based on the potential theory. In this method, fluid is considered as a velocity potential variable at each node of the shell element where its motion is expressed in terms of nodal elastic displacements at the fluid-structure interface. This proposed hybrid finite element has capabilities to do following analysis: (i) Buckling and vibration of an empty or partially fluid filled

  6. Numerical investigation of scale effect of various injection diameters on interaction in cold kerosene-fueled supersonic flow

    Science.gov (United States)

    Zhu, Lin; Qi, Yin-Yin; Liu, Wei-Lai; Xu, Bao-Jian; Ge, Jia-Ru; Xuan, Xiang-Chun; Jen, Tien-Chien

    2016-12-01

    The incident shock wave generally has a strong effect on the transversal injection field in cold kerosene-fueled supersonic flow, possibly due to its affecting the interaction between incoming flow and fuel through various operation conditions. This study is to address scale effect of various injection diameters on the interaction between incident shock wave and transversal cavity injection in a cold kerosene-fueled scramjet combustor. The injection diameters are separately specified as from 0.5 to 1.5 mm in 0.5 mm increments when other performance parameters, including the injection angle, velocity and pressure drop are all constant. A combined three dimensional Couple Level Set & Volume of Fluids (CLSVOF) approach with an improved K-H & R-T model is used to characterize penetration height, span expansion area, angle of shock wave and sauter mean diameter (SMD) distribution of the kerosene droplets with/without considering evaporation. Our results show that the injection orifice surely has a great scale effect on the transversal injection field in cold kerosene-fueled supersonic flows. Our findings show that the penetration depth, span angle and span expansion area of the transverse cavity jet are increased with the injection diameter, and that the kerosene droplets are more prone to breakup and atomization at the outlet of the combustor for the orifice diameter of 1.5 mm. The calculation predictions are compared against the reported experimental measurements and literatures with good qualitative agreement. The simulation results obtained in this study can provide the evidences for better understanding the underlying mechanism of kerosene atomization in cold supersonic flow and scramjet design improvement.

  7. Large-activation-energy analysis of gaseous reactive flow in pipes

    Science.gov (United States)

    Moreno-Boza, Daniel; Iglesias, Immaculada; Sanchez, Antonio L.

    2016-11-01

    Frank-Kamenetskii's analysis of thermal explosions is applied, using also a single-reaction model with an Arrhenius rate having a large activation energy, to describe the evolution of an initially cold gaseous mixture flowing along a circular pipe with constant wall temperature for moderately large values of the relevant Reynolds number. The analysis shows two modes of combustion. There is a flameless slowly reacting mode for low wall temperatures or small pipe radii, when the temperature rise resulting from the heat released by the reaction is kept small by the heat-conduction losses to the wall, so as not to change significantly the order of magnitude of the reaction rate. In the other mode, the slow reaction rates occur only in an initial ignition stage, which ends abruptly when very large reaction rates cause a temperature runaway, or thermal explosion, at a well-defined ignition distance. The analysis determines the slow streamwise evolution for the flameless mode of combustion as well as the ignition distance for the explosive mode.

  8. Impacts from PCB accumulation on amphibians inhabiting streams flowing from the Paducah Gaseous Diffusion Plant.

    Science.gov (United States)

    DeGarady, C J; Halbrook, R S

    2003-11-01

    Contamination at the Paducah Gaseous Diffusion Plant (PGDP), Paducah, Kentucky, has been under evaluation for many years. We studied amphibians in selected outfalls (drainage ditches) flowing from the PGDP to determine if PCBs were accumulating in their tissues and how this might affect local populations. We determined relative amphibian species richness and abundance among seven outfalls and three reference streams by listening to their calls during audio surveys. We also captured amphibians from each study site during the summers of 2000 and 2001 and analyzed their carcasses for PCBs (Aroclor 1260 and 34 congeners) and livers for ethoxyresorufin O-deethylase (EROD) activity, a biomarker of PCBs and other organic contamination. Ten species were heard across study sites, and abundance and richness at outfalls were similar to those observed at reference sites. However, there were significant differences in abundance (p = 0.001) and richness (p = 0.048) of amphibians between continuously flowing and intermittent outfalls. There were no significant differences in PCB concentrations (p = 0.113) in amphibians captured from study sites, although Aroclor 1260 concentrations tended to be higher in amphibians collected from one outfall (outfall 12) on the east side of the plant (x = 1260 microg/kg) compared with all other study sites (x = 489 microg/kg). EROD activity measured in the liver was not indicative of Aroclor 1260 concentrations in amphibians at the PGDP, and EROD did not differ by study site, species, age class, or gender. PCB concentrations measured in amphibians at the PGDP were similar to concentrations measured at reference sites and did not appear to negatively affect individual amphibians or abundance and richness.

  9. Integrated parametric study of a hybrid-stabilized argon-water arc under subsonic, transonic and supersonic plasma flow regimes

    Science.gov (United States)

    Jeništa, J.; Takana, H.; Nishiyama, H.; Bartlová, M.; Aubrecht, V.; Křenek, P.; Hrabovský, M.; Kavka, T.; Sember, V.; Mašláni, A.

    2011-11-01

    This paper presents a numerical investigation of characteristics and processes in the worldwide unique type of thermal plasma generator with combined stabilization of arc by argon flow and water vortex, the so-called hybrid-stabilized arc. The arc has been used for spraying of ceramic or metallic particles and for pyrolysis of biomass. The net emission coefficients as well as the partial characteristics methods for radiation losses from the argon-water arc are employed. Calculations for 300-600 A with 22.5-40 standard litres per minute (slm) of argon reveal transition from a transonic plasma flow for 400 A to a supersonic one for 600 A with a maximum Mach number of 1.6 near the exit nozzle of the plasma torch. A comparison with available experimental data near the exit nozzle shows very good agreement for the radial temperature profiles. Radial velocity profiles calculated 2 mm downstream of the nozzle exit show good agreement with the profiles determined from the combination of calculation and experiment (the so-called integrated approach). A recent evaluation of the Mach number from the experimental data for 500 and 600 A confirmed the existence of the supersonic flow regime.

  10. Numerical investigation on the self-excited oscillation of wet steam flow in a supersonic turbine cascade

    Institute of Scientific and Technical Information of China (English)

    LI Liang; SUN Xiuling; LI Guojun; FENG Zhenping

    2006-01-01

    The self-excited flow oscillation due to supercritical heat addition during the condensation process in wet steam turbine is an important issue. With an Eulerian/Eulerian model, the self-excited oscillation of wet steam flow in a supersonic turbine cascade is investigated. A proper inlet supercooling results in the transition from steady flow to self-excited oscillating flow in the cascade of steam turbine.The frequency dependency on the inlet supercooling is not monotonic. The flow oscillation leads to non-synchronous periodical variation of the inlet and outlet mass flow rate. The aerodynamic force on the blade varies periodically due to the self-excited flow oscillation. With the frequency lies between 18.1-80.64 Hz, the oscillating flow is apt to act with the periodical variation of the inlet supercooling due to stator rotor interaction in a syntonic pattern, and results in larger aerodynamic force on the blade. The loss in the oscillating flow increases 20.64 % compared with that in the steady flow.

  11. Hybrid Simulation of Supersonic Flow of Weakly Ionized Plasma along Open Field Magnetic Line Effect of Background Pressure

    Science.gov (United States)

    Laosunthara, Ampan; Akatsuka, Hiroshi

    2016-09-01

    In previous study, we experimentally examined physical properties of supersonic flow of weakly ionized expanding arc-jet plasma through an open magnetic field line (Bmax 0.16T). We found supersonic velocity of helium plasma up to Mach 3 and the space potential drop at the end of the magnets. To understand the plasma in numerical point of view, the flows of ion and neutral are treated by particle-based Direct Simulation Monte Carlo (DSMC) method, electron is treated as a fluid. The previous numerical study, we assumed 2 conditions. Ion and electron temperatures were the same (LTE condition). Ion and electron velocities were the same (current-free condition). We found that ion velocity decreased by collision with residual gas molecules (background pressure). We also found that space potential changing with background pressure. In other words, it was indicated that electric field exists and the current-free assumption is not proper. In this study, we add electron continuity and electron momentum equations to obtain electron velocity and space potential. We find that space potential changing with background pressure slightly. It is indicated that electron is essential to space potential formation than ion.

  12. On the Influence of Finite Rate Chemistry in LES of Self-Ignition in Vitiated Hot Confined Supersonic Air Flow

    Science.gov (United States)

    Berglund, M.; Fedina, E.; Fureby, C.; Sabel'nikov, V.; Tegnér, J.

    2009-01-01

    In this study, Large Eddy Simulation (LES) is used to analyze supersonic flow, mix ing and combustion in a supersonic combustor equipped with a two-stage fuel injector strut. An explicit LES model, using a mixed subgrid model and two different tur bulence- chemistry interaction models is used in an unstructured finite volume framework. The LES model and its components, has been carefully validated in a large number of studies. The LES predictions are compared to experimental data such as the center line wall pressure distribution and OH-PLIF distributions in two cross- sections of the combustor, showing good qualitative and quantitative agreement. The LES results are furthermore used to elucidate the complex flow, mixing and combustion physics, imposed by the multi-injector, two-stage injector strut. The importance of the chemical kinetics, although weaker than anticipated, is noticeable and must be taken into account, as is the effects of the turbulence- chemistry interaction model. It is here demonstrated that a 7-step reaction scheme is sufficient to capture mixing, self-ignition and transition into turbulent combustion responsible for most of the thrust generation in a scramjet .

  13. Numerical Analysis of Interaction Between Single-Pulse Laser-Induced Plasma and Bow Shock in a Supersonic Flow

    Institute of Scientific and Technical Information of China (English)

    FANG Juan; HONG Yanji; LI Qian

    2012-01-01

    The interaction of laser-induced plasma and bow shock over a blunt body is inves- tigated numerically in an M∞ =6.5 supersonic flow. A ray-tracing method is used for simulating the process of laser focusing. The gas located at the focused zone is ionized and broken down and transformed into plasma. In a supersonic flow the plasma moves downstream and begins to interact with the bow shock when it approaches the surface of the blunt body. The parameters of flowfield and blunt body surface are changed due to the interaction. By analyzing phenomena occurring in the complex unsteady flowfield during the interaction in detail, we can better under- stand the change of pressure on the blunt body surface and the mechanism of drag reduction by laser energy deposition. The results show that the bow shock is changed into an oblique shock due to the interaction of the laser-induced low-density zone with the bow shock, so the wave drag of the blunt body is reduced.

  14. Continuous supersonic plasma wind tunnel

    DEFF Research Database (Denmark)

    Andersen, S.A.; Jensen, Vagn Orla; Nielsen, P.

    1968-01-01

    The B field configuration of a Q-device has been modified into a magnetic Laval nozzle. Continuous supersonic plasma flow is observed with M≈3......The B field configuration of a Q-device has been modified into a magnetic Laval nozzle. Continuous supersonic plasma flow is observed with M≈3...

  15. Flow characteristic of in-flight particles in supersonic plasma spraying process

    Science.gov (United States)

    Wei, Pei; Wei, Zhengying; Zhao, Guangxi; Du, Jun; Bai, Y.

    2016-09-01

    In this paper, a computational model based on supersonic plasma spraying (SAPS) is developed to describe the plasma jet coupled with the injection of carrier gas and particles for SAPS. Based on a high-efficiency supersonic spraying gun, the 3D computational model of spraying gun was built to study the features of plasma jet and its interactions with the sprayed particles. Further the velocity and temperature of in-flight particles were measured by Spray Watch 2i, the shape of in-flight particles was observed by scanning electron microscope. Numerical results were compared with the experimental measurements and a good agreement has been achieved. The flight process of particles in plasma jet consists of three stages: accelerated stage, constant speed stage and decelerated stage. Numerical and experimental indicates that the H2 volume fraction in mixture gas of Ar + H2 should keep in the range of 23-26 %, and the distance of 100 mm is the optimal spraying distance in Supersonic atmosphere plasma spraying. Particles were melted and broken into small child particles by plasma jet and the diameters of most child particles were less than 30 μm. In general, increasing the particles impacting velocity and surface temperature can decrease the coating porosity.

  16. Chirped Pulse Microwave Spectroscopy in Pulsed Uniform Supersonic Flows: Observation of K-Dependent Rates in the CL + Propyne Reaction

    Science.gov (United States)

    Ariyasingha, Nuwandi M.; Broderick, Bernadette M.; Thompson, James O. F.; Suits, Arthur

    2016-06-01

    Chirped-Pulse Fourier-transform microwave spectroscopy in uniform supersonic flows (CPUF) has been applied to study the reaction of Cl atoms with propyne. The approach utilizes broad-band microwave spectroscopy to extract structural information with MHz resolution and near universal detection, in conjunction with a Laval flow system, which offers thermalized conditions at low temperatures and high number densities. Our previous studies have exploited this approach to obtain multichannel product branching fractions in a number of polyatomic systems, with isomer and often vibrational level specificity. This report highlights an additional capability of the CPUF technique: here, the state-specific reactant depletion is directly monitored on a microsecond timescale. In doing so, a clear dependence on the rotational quantum number K in the rate of the reaction between Cl atoms and propyne is revealed. Future prospects for the technique will be discussed.

  17. Thrust vectoring effects of a transverse gas injection into a supersonic cross flow of an axisymmetric convergent-divergent nozzle

    Science.gov (United States)

    Zmijanovic, V.; Lago, V.; Leger, L.; Depussay, E.; Sellam, M.; Chpoun, A.

    2013-03-01

    The transverse gas injection into the main supersonic flow of an axisymmetric convergent-divergent (C-D) propulsive nozzle is investigated for the fluidic thrust vectoring (FTV) possibilities as the segment part of the CNES "Perseus" project. Truncated ideal contour and conical C-D nozzles with different position and angle of the secondary circular injection port are selected as test models in the current numerical and experimental study. Analytical approach revealed parameters which affect the FTV efficiency, these criterions are further numerically explored and results data of the conical nozzle test cases are compared and coupled with the ones from experiments. It is found that upstream inclined injection has positive effect on vectoring capabilities and that with moderate secondary to primary mass-flow ratios, ranging around 5%, pertinent vector side force is possible to be achieved.

  18. Thermal MEMS flow meter for gaseous working fluids on the basis of the hot-wire thermoanemometric sensor

    Science.gov (United States)

    Tsivinskaya, T. A.; Avaeva, L. G.; Grigoriev, P. V.; Mileshin, S. A.

    2016-10-01

    This paper describes the main principles of constructing innovative MEMS flow meters for gaseous working fluids. MEMS flow meter contains hot-wire thermoanemometrisc sensor which response to the temperature change caused by convective working fluid heat transfer from a hot-wire. The advantages of using hot-wire thermoanemometric sensors were analyzed. The main emphasis of this work is on speed, construction simplicity and small size of the sensor. The new approach to the solution of a problem of sensor output signal relation with the working fluid temperature is presented. This approach is based on adding an extra temperature sensor and a special scheme for thermal compensation to the hot-wire sensor. The temperature scale between temperature sensors (thermistors) corresponds to the flow speed and the flow rate.

  19. Supersonic two-phase flow of CO{sub 2} through converging-diverging nozzles for the ejector refrigeration cycle

    Energy Technology Data Exchange (ETDEWEB)

    Nakagawa, Masafumi [Department of Mechanical and Structural System Engineering, Toyohashi University of Technology, 1-1 Hibarigaoka, Tempaku, Toyohashi City, Aichi 441-8580 (Japan); Berana, Menandro Serrano [Department of Mechanical and Structural System Engineering, Toyohashi University of Technology, 1-1 Hibarigaoka, Tempaku, Toyohashi City, Aichi 441-8580 (Japan); Department of Mechanical Engineering, University of the Philippines, Diliman, Quezon City 1101 (Philippines); Kishine, Akinori [Machine Tool Division, Murata Machinery, Ltd., 2 Nakajima, Hashizume, Inuyama City, Aichi 484-8502 (Japan)

    2009-09-15

    CO{sub 2} is environmentally friendly, safe and more suitable to ejector refrigeration cycle than to vapor compression cycle. Supersonic two-phase flow of CO{sub 2} in the diverging sections of rectangular converging-diverging nozzles was investigated. The divergence angles with significant variation of decompression were 0.076 , 0.153 , 0.306 and 0.612 . This paper presents experimental decompression phenomena which can be used in designing nozzles and an assessment of Isentropic Homogeneous Equilibrium (IHE). Inlet conditions around 6-9 MPa, 20-37 C were used to resemble ejector nozzles of coolers and heat pumps. For inlet temperature around 37 C, throat decompression boiling from the saturated liquid line, supersonic decompression and IHE solution were obtained for the two large divergence angles. For divergence angles larger than 0.306 , decompression curves for inlet temperature above 35 C approached IHE curves. For divergence angles smaller than 0.306 or for nozzles with inlet temperature below 35 C, IHE had no solution. (author)

  20. Numerical and Experimental Investigation of a Supersonic Flow Field around Solid Fuel on an Inclined Flat Plate

    Directory of Open Access Journals (Sweden)

    Uzu-Kuei Hsu

    2009-01-01

    Full Text Available This research adopts a shock tube 16 meters long and with a 9 cm bore to create a supersonic, high-temperature, and high-pressure flowfield to observe the gasification and ignition of HTPB solid fuel under different environments. Also, full-scale 3D numerical simulation is executed to enhance the comprehension of this complex phenomenon. The CFD (Computational Fluid Dynamics code is based on the control volume method and the pre-conditioning method for solving the Navier-Stokes equations to simulate the compressible and incompressible coupling problem. In the tests, a HTPB slab is placed in the windowed-test section. Various test conditions generate different supersonic Mach numbers and environmental temperatures. In addition, the incident angles of the HTPB slab were changed relative to the incoming shock wave. Results show that as the Mach number around the slab section exceeded 1.25, the flowfield temperature achieved 1100 K, which is higher than the HTPB gasification temperature (930 K ~ 1090 K. Then, gasification occurred and a short-period ignition could be observed. In particular, when the slab angle was 7∘, the phenomenon became more visible. This is due to the flow field temperature increase when the slab angle was at 7∘.

  1. Flow Matching Results of an MHD Energy Bypass System on a Supersonic Turbojet Engine Using the Numerical Propulsion System Simulation (NPSS) Environment

    Science.gov (United States)

    Benyo, Theresa L.

    2011-01-01

    Flow matching has been successfully achieved for an MHD energy bypass system on a supersonic turbojet engine. The Numerical Propulsion System Simulation (NPSS) environment helped perform a thermodynamic cycle analysis to properly match the flows from an inlet employing a MHD energy bypass system (consisting of an MHD generator and MHD accelerator) on a supersonic turbojet engine. Working with various operating conditions (such as the applied magnetic field, MHD generator length and flow conductivity), interfacing studies were conducted between the MHD generator, the turbojet engine, and the MHD accelerator. This paper briefly describes the NPSS environment used in this analysis. This paper further describes the analysis of a supersonic turbojet engine with an MHD generator/accelerator energy bypass system. Results from this study have shown that using MHD energy bypass in the flow path of a supersonic turbojet engine increases the useful Mach number operating range from 0 to 3.0 Mach (not using MHD) to a range of 0 to 7.0 Mach with specific net thrust range of 740 N-s/kg (at ambient Mach = 3.25) to 70 N-s/kg (at ambient Mach = 7). These results were achieved with an applied magnetic field of 2.5 Tesla and conductivity levels in a range from 2 mhos/m (ambient Mach = 7) to 5.5 mhos/m (ambient Mach = 3.5) for an MHD generator length of 3 m.

  2. Pressure variation by a magnetohydrodynamic method at the surface of a body placed in a supersonic flow

    Science.gov (United States)

    Lapushkina, T. A.; Erofeev, A. V.; Ponyaev, S. A.

    2014-07-01

    This study is aimed at investigating the possibility of pressure variation near the surface of a body placed in a supersonic flow as a model of an aerofoil or the nose of an aircraft by organizing a surface gas discharge in a magnetic field transverse to the flow. The flow parameters and pressure are mainly affected by the ponderomotive Lorentz force acting on the gas in the direction orthogonal to the direction of the organized discharge current and leading to the removal or compression of the gas at the surface of the body and, hence, a variation of pressure. Experimental data on the visualization of the flow and on the pressure at the surface of the body are considered for various configurations of the current and intensities of the gas discharge and magnetic field; it is demonstrated that such configurations of the current and magnetic field near the surface of the body under investigation can be organized in such a way that the pressure at the front part as well as the upper and lower surfaces of the body under investigation can be increased or decreased, thus changing the aerodynamic drag and the aerofoil lift. Such a magnetohydrodynamic control over aerodynamic parameters of the aircraft can be used during takeoff and landing as well as during steady-state flight and also during the entrance into dense atmospheric layers. This will considerably reduce the thermal load on the surface of the body in the flow.

  3. Schlieren study of a sonic jet injected into a supersonic cross flow using high-current pulsed LEDs

    CERN Document Server

    Giskes, Ella; Segerink, Frans B; Venner, Cornelis H

    2016-01-01

    In the research of supersonic flows, flow visualization continues to be an important tool, and even today it is difficult to create high quality images. In this study we present a low-cost and easy-to use Schlieren setup. The setup makes use of LEDs, pulsed with high currents to increase the optical output to sufficient levels, exploiting the advantages of LED light over conventional light sources. As a test-case we study the interaction of a Mach 1.7 cross flow and a transverse underexpanded jet, which is commonly studied considering the mixing and combustion in scramjet engines. Using 130 nanosecond LED light pulses, we captured the flow structures sharply and in great detail. We observed a large-gradient wave, which was seen in numerical studies but hitherto not reported in experiments. Furthermore, we demonstrate that time-correlated images can be obtained with this Schlieren setup, so that also flow unsteadiness can be studied, such as the movement of shock waves and vortices.

  4. Supersonic unstalled flutter

    Science.gov (United States)

    Adamczyk, J. J.; Goldstein, M. E.; Hartmann, M. J.

    1978-01-01

    Recently two flutter analyses have been developed at NASA Lewis Research Center to predict the onset of supersonic unstalled flutter of a cascade of two-dimensional airfoils. The first of these analyzes the onset of supersonic flutter at low levels of aerodynamic loading (i.e., backpressure), while the second examines the occurrence of supersonic flutter at moderate levels of aerodynamic loading. Both of these analyses are based on the linearized unsteady inviscid equations of gas dynamics to model the flow field surrounding the cascade. The details of the development of the solution to each of these models have been published. The objective of the present paper is to utilize these analyses in a parametric study to show the effects of cascade geometry, inlet Mach number, and backpressure on the onset of single and multi degree of freedom unstalled supersonic flutter. Several of the results from this study are correlated against experimental qualitative observation to validate the models.

  5. Quantifying equation-of-state and opacity errors using integrated supersonic diffusive radiation flow experiments on the National Ignition Facility

    Energy Technology Data Exchange (ETDEWEB)

    Guymer, T. M., E-mail: Thomas.Guymer@awe.co.uk; Moore, A. S.; Morton, J.; Allan, S.; Bazin, N.; Benstead, J.; Bentley, C.; Comley, A. J.; Garbett, W.; Reed, L.; Stevenson, R. M. [AWE Plc., Aldermaston, Reading RG7 4PR (United Kingdom); Kline, J. L.; Cowan, J.; Flippo, K.; Hamilton, C.; Lanier, N. E.; Mussack, K.; Obrey, K.; Schmidt, D. W.; Taccetti, J. M. [Los Alamos National Laboratory, Los Alamos, New Mexico 87545 (United States); and others

    2015-04-15

    A well diagnosed campaign of supersonic, diffusive radiation flow experiments has been fielded on the National Ignition Facility. These experiments have used the accurate measurements of delivered laser energy and foam density to enable an investigation into SESAME's tabulated equation-of-state values and CASSANDRA's predicted opacity values for the low-density C{sub 8}H{sub 7}Cl foam used throughout the campaign. We report that the results from initial simulations under-predicted the arrival time of the radiation wave through the foam by ≈22%. A simulation study was conducted that artificially scaled the equation-of-state and opacity with the intended aim of quantifying the systematic offsets in both CASSANDRA and SESAME. Two separate hypotheses which describe these errors have been tested using the entire ensemble of data, with one being supported by these data.

  6. Effect of substrate temperature on the structure of amorphous oxygenated hydrocarbon films grown with a pulsed supersonic methane plasma flow

    Energy Technology Data Exchange (ETDEWEB)

    Fedoseeva, Yu. V., E-mail: fedoseeva@niic.nsc.ru [Nikolaev Institute of Inorganic Chemistry SB RAS, Novosibirsk 630090 (Russian Federation); Novosibirsk State University, Novosibirsk 630090 (Russian Federation); Pozdnyakov, G.A. [Khristianovich Institute of Theoretical and Applied Mechanics, SB RAS, Novosibirsk 630090 (Russian Federation); Okotrub, A.V.; Kanygin, M.A. [Nikolaev Institute of Inorganic Chemistry SB RAS, Novosibirsk 630090 (Russian Federation); Novosibirsk State University, Novosibirsk 630090 (Russian Federation); Nastaushev, Yu. V. [Rzhanov Institute of Semiconductor Physics SB RAS, Novosibirsk 630090 (Russian Federation); Vilkov, O.Y. [St. Petersburg State University, St. Petersburg 198504 (Russian Federation); Bulusheva, L.G. [Nikolaev Institute of Inorganic Chemistry SB RAS, Novosibirsk 630090 (Russian Federation); Novosibirsk State University, Novosibirsk 630090 (Russian Federation)

    2016-11-01

    Highlights: • A deposition of supersonic methane plasma flow on silicon substrate produces amorphous oxygenated hydrocarbon (CO{sub x}H{sub y}) film. • The thickness, composition, and wettability of the film depend on the substrate temperature. • A rise of the substrate temperature from 500 to 700 °C promotes the sp{sup 3}-hybridization carbon formation. - Abstract: Since amorphous oxygenated hydrocarbon (CO{sub x}H{sub y}) films are promising engineering materials a study of the structure and composition of the films depending on the conditions of synthesis is important for controlling of their physicochemical properties. Here, we used the methods of scanning and transmission electron microscopy, X-ray photoelectron, near-edge X-ray absorption fine structure, Fourier transform infrared and Raman spectroscopy to reveal changes in the chemical connectivity of CO{sub x}H{sub y} films grown on silicon substrates heated to 300, 500, and 700 °C using a supersonic flow of methane plasma. It was found that the CO{sub x}H{sub y} films, deposited at 300 and 500 °C, were mainly composed of the sp{sup 2}-hybridized carbon areas with various oxygen species. A rise of the substrate temperature caused an increase of the portion of tetrahedral carbon atoms as well as carboxyl and hydroxyl groups. With growth of the substrate temperature, the film thickness reduced monotonically from 400 to 180 nm, while the film adhesion improved substantially. The films, deposited at lower temperatures, showed high hydrophilicity due to porosity and presence of oxygenated groups both at the surface and in the bulk.

  7. Initial Flow Matching Results of MHD Energy Bypass on a Supersonic Turbojet Engine Using the Numerical Propulsion System Simulation (NPSS) Environment

    Science.gov (United States)

    Benyo, Theresa L.

    2010-01-01

    Preliminary flow matching has been demonstrated for a MHD energy bypass system on a supersonic turbojet engine. The Numerical Propulsion System Simulation (NPSS) environment was used to perform a thermodynamic cycle analysis to properly match the flows from an inlet to a MHD generator and from the exit of a supersonic turbojet to a MHD accelerator. Working with various operating conditions such as the enthalpy extraction ratio and isentropic efficiency of the MHD generator and MHD accelerator, interfacing studies were conducted between the pre-ionizers, the MHD generator, the turbojet engine, and the MHD accelerator. This paper briefly describes the NPSS environment used in this analysis and describes the NPSS analysis of a supersonic turbojet engine with a MHD generator/accelerator energy bypass system. Results from this study have shown that using MHD energy bypass in the flow path of a supersonic turbojet engine increases the useful Mach number operating range from 0 to 3.0 Mach (not using MHD) to an explored and desired range of 0 to 7.0 Mach.

  8. The impact of primordial supersonic flows on early structure formation, reionization and the lowest-mass dwarf galaxies

    CERN Document Server

    Maio, Umberto; Ciardi, Benedetta

    2010-01-01

    Tseliakhovich & Hirata recently discovered that higher-order corrections to the cosmological linear-perturbation theory lead to supersonic coherent baryonic flows just after recombination (i.e.\\ $z \\approx 1020$), with rms velocities of $\\sim$30 km/s relative to the underlying dark-matter distribution, on comoving scales of $\\la 3$ Mpc\\,$h^{-1}$. To study the impact of these coherent flows we performed high-resolution N-body plus SPH simulations in boxes of 5.0 and 0.7 Mpc\\,$h^{-1}$, for bulk-flow velocities of 0 (as reference), 30 and 60 km/s. The simulations follow the evolution of cosmic structures by taking into account detailed, primordial, non-equilibrium gas chemistry (i.e.\\ H, He, H$_2$, HD, HeH, etc.), cooling, star formation, and feedback effects from stellar evolution. We find that these bulk flows suppress star formation in low-mass haloes (i.e.\\ $M_{\\rm vir} \\la 10^8$M$_{\\odot}$ until $z\\sim 13$), lower the abundance of the first objects by $\\sim 1%-20%$, and, as consequence, delay cosmic sta...

  9. Supersonic flow. Pt. 5 Shock waves; Fondamenti fisici dei fasci molecolari supersonici. Pt 5 Onde di Shock

    Energy Technology Data Exchange (ETDEWEB)

    Sanna, G.; Tomassetti, G. [L`Aquila Univ. (Italy). Dipt. di Fisica

    1998-02-01

    The discontinuities in the flow fields (both tangential and shocks) are considered and the equations for the quantities conserved across them are written. The post-shock flow variables are expressed by the Mach number of the incident supersonic flow and its deflection angle operated by rigid wall. Normal and oblique shocks are considered and graphs and polar diagrams are introduced. Then the reflections of a shock wave operated by a rigid wall and by the boundary between a jet and a stagnating gas are analyzed. Finally, the interactions between two distinct shock waves are considered. [Italiano] Vengono considerate le discontinuita` (tangenziali e shocks) nei campi di flusso e sono scritte le equazioni per le quantita` che si conservano attraverso di esse. Le variabili del flusso oltre lo shock sono espresse in funzione del numero di Mach del flusso supersonico incidente e dell`angolo di deflessione di questo operato da una parete rigida. I casi di shock normale, obliquo e distaccato sono considerati e sono introdotti grafici vari e rappresentazioni polari. Sono quindi considerate le riflessioni di un fronte di shock da una parete rigida e dalla frontiera tra un gas in moto ed uno stagnante. Sono infine considerate le diverse interazioni tra due shock distinti.

  10. Velocity Slip and Interfacial Momentum Transfer in the Transient Section of Supersonic Gas-Droplet Two-Phase Flows

    Institute of Scientific and Technical Information of China (English)

    魏文韫; 朱家骅; 夏素兰; 戴光清; 高旭东

    2002-01-01

    Modelling and simulations are conducted on velocity slip and interfacial momentum transfer for super-sonic two-phase (gas-droplet) flow in the transient section inside and outside a Laval jet(L J). The initial velocity slipbetween gas and droplets causes an interfacial momentum transfer flux as high as (2.0-5.0) × 104 Pa. The relaxationtime corresponding to this transient process is in the range of 0.015-0.090 ms for the two-phase flow formed insidethe LJ and less than 0.5 ms outside the LJ. It demonstrates the unique performance of this system for application tofast chemical reactions using electrically active media with a lifetime in the order of 1 ms. Through the simulationsof the transient processes with initial Mach number Mg from 2.783 to 4.194 at different axial positions inside theLJ. it is found that Mg has the strongest effect on the process. The momentum flux increases as the Mach numberdecreases. Due to compression by the shock wave at the end of the L J, the flow pattern becomes two dimensionaland viscous outside the LJ. Laser Doppler velocimeter (LDV) measurements of droplet velocities outside the LJ arein reasonably good agreement with the results of the simulation.

  11. The capability of trapping gaseous microemboli of two pediatric arterial filters with pulsatile and nonpulsatile flow in a simulated infant CPB model.

    Science.gov (United States)

    Wang, Shigang; Win, Khin N; Kunselman, Allen R; Woitas, Karl; Myers, John L; Undar, Akif

    2008-01-01

    The study objective was to test the capability of Medtronic Affinity and Terumo Capiox pediatric arterial filters to trap gaseous microemboli in a simulated infant cardiopulmonary bypass (CPB) model. The filters were used in parallel pattern. The circuit was primed with lactated ringer's solution (700 ml) and postfilter pressure was maintained at 100 mm Hg using a Hoffman clamp. Trials were conducted at flow rates ranging from 500 to 1,250 ml/min. After introducing 20 ml air into the venous line via an 18-G needle, 2-minute segments of data were recorded. This entire process was repeated 6 times for each unique combination of arterial filter, flow rate and perfusion mode, yielding a total of 96 experiments. More than 80% of gaseous microemboli were trapped by the two pediatric arterial filters. With increased flow rates and pulsatile mode, more gaseous microemboli passed through the arterial filters. There were no differences in terms of the percentage of gaseous microemboli trapped and pressure drops between Medtronic Affinity and Terumo Capiox pediatric arterial filters. Results demonstrated that Medtronic Affinity and Terumo Capiox pediatric arterial filters could trap the majority of gaseous microemboli in this particular setting of an open arterial filter purge line in a simulated infant CPB circuit with pulsatile and nonpulsatile flow.

  12. Gusty, gaseous flows of FIRE: galactic winds in cosmological simulations with explicit stellar feedback

    CERN Document Server

    Muratov, Alexander L; Faucher-Giguere, Claude-Andre; Hopkins, Philip F; Quataert, Eliot; Murray, Norman

    2015-01-01

    We present an analysis of the galaxy-scale gaseous outflows from the FIRE (Feedback in Realistic Environments) simulations. This suite of hydrodynamic cosmological zoom simulations provides a sample of halos where star-forming giant molecular clouds are resolved to z=0, and features an explicit stellar feedback model on small scales. In this work, we focus on quantifying the gas mass ejected out of galaxies in winds and how this material travels through the halo. We correlate these quantities to star formation in galaxies throughout cosmic history. Our simulations reveal that a significant portion of every galaxy's evolution, particularly at high redshift, is dominated by bursts of star formation, which are followed by powerful gusts of galactic outflow that sweep up a large fraction of gas in the interstellar medium and send it through the circumgalactic medium. The dynamical effect of these outflows can significantly limit the amount of star formation within the affected galaxy. At low redshift, however, su...

  13. Skin Friction and Pressure Measurements in Supersonic Inlets Project

    Data.gov (United States)

    National Aeronautics and Space Administration — Supersonic propulsion systems include internal ducts, and therefore, the flow often includes shock waves, shear layers, vortices, and separated flows. Passive flow...

  14. TranAir: A full-potential, solution-adaptive, rectangular grid code for predicting subsonic, transonic, and supersonic flows about arbitrary configurations. User's manual

    Science.gov (United States)

    Johnson, F. T.; Samant, S. S.; Bieterman, M. B.; Melvin, R. G.; Young, D. P.; Bussoletti, J. E.; Hilmes, C. L.

    1992-01-01

    The TranAir computer program calculates transonic flow about arbitrary configurations at subsonic, transonic, and supersonic freestream Mach numbers. TranAir solves the nonlinear full potential equations subject to a variety of boundary conditions modeling wakes, inlets, exhausts, porous walls, and impermeable surfaces. Regions with different total temperature and pressure can be represented. The user's manual describes how to run the TranAir program and its graphical support programs.

  15. Three-Dimensional Inviscid Flow About Supersonic Blunt Cones at Angle of Attack - I: Numerical Technique for the Three-Dimensional Blunt-Body Problem

    Energy Technology Data Exchange (ETDEWEB)

    Moretti, G.; Bleich, G.

    1968-09-01

    The three-dimensional flow field around blunted bodies traveling at supersonic speed is computed using a time-dependent technique. The problem is mathematically well posed, the technique is stable and its accuracy increases with the fineness of the mesh. Values at points within the shock layer are computed by a method closely related to the Lax-Wendroff technique. Values at shock points and body points are computed by a four-dimensional method of characteristics.

  16. Influence of Mach number and static pressure on plasma flow control of supersonic and rarefied flows around a sharp flat plate

    Science.gov (United States)

    Coumar, Sandra; Lago, Viviana

    2017-06-01

    This paper presents an experimental investigation, carried out at the Icare Laboratory by the FAST team, focusing on plasma flow control in supersonic and rarefied regime. The study analyzes how the Mach number as well as the ambient pressure modify the repercussions of the plasma actuator on the shock wave. It follows previous experiments performed in the MARHy (ex-SR3) wind tunnel with a Mach 2 flow interacting with a sharp flat plate, where modifications induced by a plasma actuator were observed. The flat plate was equipped with a plasma actuator composed of two aluminum electrodes. The upstream one was biased with a negative DC potential and thus, created a glow discharge type plasma. Experimental measurements showed that the boundary layer thickness and the shock wave angle increased when the discharge was ignited. The current work was performed with two nozzles generating Mach 4 flows but at two different static pressures: 8 and 71 Pa. These nozzles were chosen to study independently the impact of the Mach number and the impact of the pressure on the flow behavior. In the range of the discharge current considered in this experimental work, it was observed that the shock wave angle increased with the discharge current of +15% for the Mach 2 flow but the increase rate doubled to +28% for the Mach 4 flow at the same static pressure, showing that the discharge effect is even more significant when boosting the flow speed. When studying the effect of the discharge on the Mach 4 flow at higher static pressure, it was observed that the topology of the plasma changed drastically and the increase in the shock wave angle with the discharge current of +21 %.

  17. High Enthalpy Effects on Two Boundary Layer Disturbances in Supersonic and Hypersonic Flow

    Science.gov (United States)

    2012-05-01

    178 C.1 Modified Millikan and White relaxation times...131 6.30 This plot shows the LST stability diagram for the case of cold carbon dioxide injection at a rate of 6 g/s. The sharp drop in amplified...boundary layer. Whitehead[77] used surface oil flow to visualize CHAPTER 2. BACKGROUND 21 the flow features around isolated roughness elements in

  18. Effect of substrate temperature on the structure of amorphous oxygenated hydrocarbon films grown with a pulsed supersonic methane plasma flow

    Science.gov (United States)

    Fedoseeva, Yu. V.; Pozdnyakov, G. A.; Okotrub, A. V.; Kanygin, M. A.; Nastaushev, Yu. V.; Vilkov, O. Y.; Bulusheva, L. G.

    2016-11-01

    Since amorphous oxygenated hydrocarbon (COxHy) films are promising engineering materials a study of the structure and composition of the films depending on the conditions of synthesis is important for controlling of their physicochemical properties. Here, we used the methods of scanning and transmission electron microscopy, X-ray photoelectron, near-edge X-ray absorption fine structure, Fourier transform infrared and Raman spectroscopy to reveal changes in the chemical connectivity of COxHy films grown on silicon substrates heated to 300, 500, and 700 °C using a supersonic flow of methane plasma. It was found that the COxHy films, deposited at 300 and 500 °C, were mainly composed of the sp2-hybridized carbon areas with various oxygen species. A rise of the substrate temperature caused an increase of the portion of tetrahedral carbon atoms as well as carboxyl and hydroxyl groups. With growth of the substrate temperature, the film thickness reduced monotonically from 400 to 180 nm, while the film adhesion improved substantially. The films, deposited at lower temperatures, showed high hydrophilicity due to porosity and presence of oxygenated groups both at the surface and in the bulk.

  19. Numerical Simulations of Flow in a 3-D Supersonic Intake at High Mach Numbers

    Directory of Open Access Journals (Sweden)

    R. Sivakumar

    2006-10-01

    Full Text Available Numerical simulations of the compressible, 3-D non reacting flow in the engine inlet sectionof a concept hypersonic air-breathing vehicle are presented. These simulations have been carriedout using FLUENT. For all the results reported, the mesh has been refined to achieve areaaveragedwall y+ about 105. Mass flow rate through the intake and stagnation pressure recoveryare used to compare the performance at various angles of attack. The calculations are able topredict the mode of air-intake operation (critical and subcritical for different angles of attack.Flow distortion at the intake for various angles of attack is also calculated and discussed. Thenumerical results are validated by simulating the flow through a 2-D mixed compression hypersonicintake model and comparing with the experimental data.

  20. NASA Ames Laminar Flow Supersonic Wind Tunnel (LFSWT) Tests of a 10 deg Cone at Mach 1.6

    Science.gov (United States)

    Wolf, Stephen W. D.; Laub, James A.

    1997-01-01

    This work is part of the ongoing qualification of the NASA Ames Laminar Flow Supersonic Wind Tunnel (LFSWT) as a low-disturbance (quiet) facility suitable for transition research. A 10 deg cone was tested over a range of unit Reynolds numbers (Re = 2.8 to 3.8 million per foot (9.2 to 12.5 million per meter)) and angles of incidence (O deg to 10 deg) at Mach 1.6. The location of boundary layer transition along the cone was measured primarily from surface temperature distributions, with oil flow interferometry and Schlieren flow visualization providing confirmation measurements. With the LFSWT in its normal quiet operating mode, no transition was detected on the cone in the test core, over the Reynolds number range tested at zero incidence and yaw. Increasing the pressure disturbance levels in the LFSWT test section by a factor of five caused transition onset on the cone within the test core, at zero incidence and yaw. When operating the LFSWT in its normal quiet mode, transition could only be detected in the test core when high angles of incidence (greater than 5 deg) for cones were set. Transition due to elevated pressure disturbances (Tollmien-Schlichting) and surface trips produced a skin temperature rise of order 4 F (2.2 C). Transition due to cross flows on the leeward side of the cone at incidence produced a smaller initial temperature rise of only order 2.5 F (1.4 C), which indicates a slower transition process. We can conclude that these cone tests add further proof that the LFSWT test core is normally low-disturbance (pressure fluctuations greater than 0.1%), as found by associated direct flow quality measurements discussed in this report. Furthermore, in a quiet test environment, the skin temperature rise is sensitive to the type of dominant instability causing transition. The testing of a cone in the LFSWT provides an excellent experiment for the development of advanced transition detection techniques.

  1. Identifying Coherent Structures in a 3-Stream Supersonic Jet Flow using Time-Resolved Schlieren Imaging

    Science.gov (United States)

    Tenney, Andrew; Coleman, Thomas; Berry, Matthew; Magstadt, Andy; Gogineni, Sivaram; Kiel, Barry

    2015-11-01

    Shock cells and large scale structures present in a three-stream non-axisymmetric jet are studied both qualitatively and quantitatively. Large Eddy Simulation is utilized first to gain an understanding of the underlying physics of the flow and direct the focus of the physical experiment. The flow in the experiment is visualized using long exposure Schlieren photography, with time resolved Schlieren photography also a possibility. Velocity derivative diagnostics are calculated from the grey-scale Schlieren images are analyzed using continuous wavelet transforms. Pressure signals are also captured in the near-field of the jet to correlate with the velocity derivative diagnostics and assist in unraveling this complex flow. We acknowledge the support of AFRL through an SBIR grant.

  2. Wedge Shock and Nozzle Exhaust Plume Interaction in a Supersonic Jet Flow

    Science.gov (United States)

    Castner, Raymond; Zaman, Khairul; Fagan, Amy; Heath, Christopher

    2014-01-01

    Fundamental research for sonic boom reduction is needed to quantify the interaction of shock waves generated from the aircraft wing or tail surfaces with the nozzle exhaust plume. Aft body shock waves that interact with the exhaust plume contribute to the near-field pressure signature of a vehicle. The plume and shock interaction was studied using computational fluid dynamics and compared with experimental data from a coaxial convergent-divergent nozzle flow in an open jet facility. A simple diamond-shaped wedge was used to generate the shock in the outer flow to study its impact on the inner jet flow. Results show that the compression from the wedge deflects the nozzle plume and shocks form on the opposite plume boundary. The sonic boom pressure signature of the nozzle exhaust plume was modified by the presence of the wedge. Both the experimental results and computational predictions show changes in plume deflection.

  3. Turbulence measurements in axisymmetric supersonic boundary layer flow in adverse pressure gradients

    Science.gov (United States)

    Gootzait, E.; Childs, M. E.

    1977-01-01

    Mean flow and turbulence measurements are presented for adiabatic compressible turbulent boundary layer flow in adverse pressure gradients. The gradients were induced on the wall of an axially symmetric wind tunnel by contoured centerbodies mounted on the wind tunnel centerline. The boundary layer turbulence downstream of a boundary layer bleed section in a zero pressure gradient was also examined. The measurements were obtained using a constant temperature hot-wire anemometer. The adverse pressure gradients were found to significantly alter the turbulence properties of the boundary layer. With flow through the bleed holes there was a measureable decrease in the rms longitudinal velocity fluctuations near the wall and the turbulent shear stress in the boundary layer was reduced.

  4. Stability of a cantilevered skew inhomogeneous plate in supersonic gas flow

    Science.gov (United States)

    Isaulova, T. N.; Lavit, I. M.

    2011-07-01

    This paper considers the vibrations of a skew inhomogeneous plate in gas flow. The plate is clamped in a certain section of one of its sides. Interaction of the flow with the plate is described using piston theory. The problem solution is based on the Hamilton's variational principle and finite element method. The calculation results are compared with known data of theoretical studies and experiments. For the inhomogeneous plate, similarity parameters were established for the problem, which, in practically important cases, appears to be self-similar for one of the similarity parameters. This allows one to reduce the solution of this problem to the solution of an algebraic eigenvalue problem.

  5. Semi-analytical and 3D CFD DPAL modeling: feasibility of supersonic operation

    Science.gov (United States)

    Rosenwaks, Salman; Barmashenko, Boris D.; Waichman, Karol

    2014-02-01

    The feasibility of operating diode pumped alkali lasers (DPALs) with supersonic expansion of the gaseous laser mixture, consisting of alkali atoms, He atoms and (frequently) hydrocarbon molecules, is explored. Taking into account fluid dynamics and kinetic processes, both semi-analytical and three-dimensional (3D) computational fluid dynamics (CFD) modeling of supersonic DPALs is reported. Using the semi-analytical model, the operation of supersonic DPALs is compared with that measured and modeled in subsonic lasers for both Cs and K. The maximum power of supersonic Cs and K lasers is found to be higher than that of subsonic lasers with the same resonator and alkali density at the laser inlet by 25% and 70%, respectively. Using the 3D CFD model, the flow pattern and spatial distributions of the pump and laser intensities in the resonator are calculated for Cs DPALs. Comparison between the semi-analytical and 3D CFD models for Cs shows that the latter predicts much larger maximum achievable laser power than the former. These results indicate that for scaling-up the power of DPALs, supersonic expansion should be considered.

  6. Free-path distribution and Knudsen-layer modeling for gaseous flows in the transition regime

    Science.gov (United States)

    To, Quy Dong; Léonard, Céline; Lauriat, Guy

    2015-02-01

    In this paper, we use molecular dynamics (MD) simulations to study the mean free path distribution of nonequilibrium gases in micronanochannel and to model the Knudsen (Kn) layer effect. It is found that the mean free path is significantly reduced near the wall and rather insensitive to flow types (Poiseuille or Couette). The Cercignani relation between the mean free path and the viscosity is adopted to capture the velocity behavior of the special zone in the framework of the extended Navier-Stokes (NS) equations. MD simulations of flows are carried out at different Kn numbers. Results are then compared with the theoretical model.

  7. Investigation of the compressible flow through the tip-section turbine blade cascade with supersonic inlet

    Science.gov (United States)

    Luxa, Martin; Příhoda, Jaromír; Šimurda, David; Straka, Petr; Synáč, Jaroslav

    2016-04-01

    The contribution deals with the experimental and numerical investigation of compressible flow through the tip-section turbine blade cascade with the blade 54″ long. Experimental investigations by means of optical (interferometry and schlieren method) and pneumatic measurements provide more information about the behaviour and nature of basic phenomena occurring in the profile cascade flow field. The numerical simulation was carried out by means of the EARSM turbulence model according to Hellsten [5] completed by the bypass transition model with the algebraic equation for the intermittency coefficient proposed by Straka and Příhoda [6] and implemented into the in-house numerical code. The investigation was focused particularly on the effect of shock waves on the shear layer development including the laminar/turbulent transition. Interactions of shock waves with shear layers on both sides of the blade result usually in the transition in attached and/ or separated flow and so to the considerable impact to the flow structure and energy losses in the blade cascade.

  8. Turbulence models and Reynolds analogy for two-dimensional supersonic compression ramp flow

    Science.gov (United States)

    Wang, Chi R.; Bidek, Maleina C.

    1994-01-01

    Results of the application of turbulence models and the Reynolds analogy to the Navier-Stokes computations of Mach 2.9 two-dimensional compression ramp flows are presented. The Baldwin-Lomax eddy viscosity model and the kappa-epsilon turbulence transport equations for the turbulent momentum flux modeling in the Navier-Stokes equations are studied. The Reynolds analogy for the turbulent heat flux modeling in the energy equation was also studied. The Navier-Stokes equations and the energy equation were numerically solved for the flow properties. The Reynolds shear stress, the skin friction factor, and the surface heat transfer rate were calculated and compared with their measurements. It was concluded that with a hybrid kappa-epsilon turbulence model for turbulence modeling, the present computations predicted the skin friction factors of the 8 deg and 16 deg compression ramp flows and with the turbulent Prandtl number Pr(sub t) = 0.93 and the ratio of the turbulent thermal and momentum transport coefficients mu(sub q)/mu(sub t) = 2/Prt, the present computations also predicted the surface heat transfer rates beneath the boundary layer flow of the 16 compression ramp.

  9. Characterization of the three-dimensional supersonic flow for the MHD generator

    Institute of Scientific and Technical Information of China (English)

    LU HaoYu; LEE ChunHian; DONG HaiTao

    2009-01-01

    A numerical procedure based on a five-wave MHD model associated with non-ideal, low magnetic Reynolds number MHD flows was developed in the present study for analyzing the flow fields in the MHD generator of a MHD bypass scramjet. The numerical procedure is composed of an entropy condi-tioned scheme for solving the non-homogeneous Navier-Stokes equations, in conjunction with an SOR method for solving the elliptic equation governing the electrical potential. It was found that a separation would take place near the downstream edge of the second electrode, where the local adverse pressure gradient is large, and the core of the flow field is characterized as a 2-D flow due to the Hartmann ef-fects along the direction of the magnetic field. The electric current lines would be increasingly distorted as the magnetic interactive parameter increases, and even induce an eddy current. Induced eddy cur-rent was also found in the different cross-sections along the axial direction, all of these would definitely deteriorate the performance of the MHD generator. The cross-sectional M-shape velocity profile found along the axial direction between the insulating walls is responsible for the formation of the vortex flow at the corner of the insulator cross-section, which, in turn, induces the corner eddy current at the cor-ner. A numerical parametric study was also performed, and the computed performance parameters for the MHD generator suggest that, in order to enhance the performance of MHD generator, the magnetic interaction parameter should be elevated.

  10. Characterization of the three-dimensional supersonic flow for the MHD generator

    Institute of Scientific and Technical Information of China (English)

    LEE; ChunHian

    2009-01-01

    A numerical procedure based on a five-wave MHD model associated with non-ideal,low magnetic Reynolds number MHD flows was developed in the present study for analyzing the flow fields in the MHD generator of a MHD bypass scramjet. The numerical procedure is composed of an entropy conditioned scheme for solving the non-homogeneous Navier-Stokes equations,in conjunction with an SOR method for solving the elliptic equation governing the electrical potential. It was found that a separation would take place near the downstream edge of the second electrode,where the local adverse pressure gradient is large,and the core of the flow field is characterized as a 2-D flow due to the Hartmann effects along the direction of the magnetic field. The electric current lines would be increasingly distorted as the magnetic interactive parameter increases,and even induce an eddy current. Induced eddy current was also found in the different cross-sections along the axial direction,all of these would definitely deteriorate the performance of the MHD generator. The cross-sectional M-shape velocity profile found along the axial direction between the insulating walls is responsible for the formation of the vortex flow at the corner of the insulator cross-section,which,in turn,induces the corner eddy current at the corner. A numerical parametric study was also performed,and the computed performance parameters for the MHD generator suggest that,in order to enhance the performance of MHD generator,the magnetic interaction parameter should be elevated.

  11. Experimental Study of Shock-train/Combustion Coupling and Flame Dynamics in a Heated Supersonic Flow

    Science.gov (United States)

    Fotia, Matthew Leonard

    Isolator/combustor interactions are measured in a direct-connect dual-mode ramjet-scramjet experiment. An operating point approach is used to create a mapping of the coupling effects between the isolator geometry, inlet flow conditions and fuel injector behavior. The resulting isolator/injector coupling map provides a description of the response of the isolator to particular injector performance, and the effective blockage it induces on the isolator flow. Existing models and correlations predicting the pressure rise across a pseudo-shock, and its resultant length, were evaluated through comparison with measurements made in a heated-flow isolator duct that is coupled to a hydrogen-air combustor. The observation of a normal-to-oblique shock-train transition mechanism has lead to the development of a revised shock-train operating regime description that takes into account the impact of Mach number and maximum pressure recovery on the shock configurations present in the isolator. The behavior of a ram-scram transition was examined along with pressure measurements and high-speed laser interferometry. The work quantifies the sudden change in the wall static pressure profile and flame position that occurs as the downstream boundary condition abruptly changes when the flow becomes unchoked. Transition was studied in three ways; as a quasi-steady phenomenon, or as caused by rapid variations in either fuel flow-rate or test-section wall temperature. A regime diagram was measured that plots the ram-scram transition boundary. Under certain conditions some periodic low-frequency oscillations of the flame position occur and they are shown to be correlated with oscillations of the upstream pre-combustion pseudo-shock. A self-sustaining shear-layer instability, associated with the flameholding cavity, is identified as the mechanism perpetuating this behavior. The relevant time scales associated with the ram-scram transition and the flame-shock interactions are discussed.

  12. Study of Mechanisms of Filamentary Pulse Electric Discharge Interaction with Gaseous Flow of Nonuniform Composition

    Science.gov (United States)

    2013-06-01

    plasma-chemical reactions excitation in the systems of exhaust gases cleaning; ozone generation by the DBD; the powerful fast spark switches...experiments in CO-air, ethylene- air, and methane-air flows using FTIR absorption spectroscopy and visible emission spectroscopy. Results of combustion

  13. The flow over a 'high' aspect ratio gothic wing at supersonic speeds

    Science.gov (United States)

    Narayan, K. Y.

    1975-01-01

    Results are presented of an experimental investigation on a nonconical wing which supports an attached shock wave over a region of the leading edge near the vertex and a detached shock elsewhere. The shock detachment point is determined from planform schlieren photographs of the flow field and discrepancies are shown to exist between this and the one calculated by applying the oblique shock equations normal to the leading edge. On a physical basis, it is argued that the shock detachment has to obey the two-dimensional law normal to the leading edges. From this, and from other measurements on conical wings, it is thought that the planform schlieren technique may not be particularly satisfactory for detecting shock detachment. Surface pressure distributions are presented and are explained in terms of the flow over related delta wings which are identified as a vertex delta wing and a local delta wing.

  14. Numerical Simulation on Supersonic Flow in High-Velocity Oxy-Fuel Thermal Spray Gun

    Institute of Scientific and Technical Information of China (English)

    Hiroshi KATANODA; Hideki YAMAMOTO; Kazuyasu MATSUO

    2006-01-01

    This paper analyzes the behaviour of coating particles as well as the gas flow both inside and outside of the High-Velocity Oxy-Fuel (HVOF) thermal spray gun by using a quasi-one-dimensional analysis and a numerical simulation. The HVOF gun in the present analysis is an axially symmetric convergent-divergent nozzle with the design Mach number of 2.0. From the present analysis, the distributions of velocity and temperature of the coating particles flying inside and outside of the HVOF gun are predicted. The velocity and temperature of the coating particles at the exit of the gun calculated by the present method agree well with the previous experimental results. Therefore, the present method of calculation is considered to be useful for predicting the HVOF gas and particle flows.

  15. MONOTONIC DERIVATIVE CORRECTION FOR CALCULATION OF SUPERSONIC FLOWS WITH SHOCK WAVES

    Directory of Open Access Journals (Sweden)

    P. V. Bulat

    2015-07-01

    Full Text Available Subject of Research. Numerical solution methods of gas dynamics problems based on exact and approximate solution of Riemann problem are considered. We have developed an approach to the solution of Euler equations describing flows of inviscid compressible gas based on finite volume method and finite difference schemes of various order of accuracy. Godunov scheme, Kolgan scheme, Roe scheme, Harten scheme and Chakravarthy-Osher scheme are used in calculations (order of accuracy of finite difference schemes varies from 1st to 3rd. Comparison of accuracy and efficiency of various finite difference schemes is demonstrated on the calculation example of inviscid compressible gas flow in Laval nozzle in the case of continuous acceleration of flow in the nozzle and in the case of nozzle shock wave presence. Conclusions about accuracy of various finite difference schemes and time required for calculations are made. Main Results. Comparative analysis of difference schemes for Euler equations integration has been carried out. These schemes are based on accurate and approximate solution for the problem of an arbitrary discontinuity breakdown. Calculation results show that monotonic derivative correction provides numerical solution uniformity in the breakdown neighbourhood. From the one hand, it prevents formation of new points of extremum, providing the monotonicity property, but from the other hand, causes smoothing of existing minimums and maximums and accuracy loss. Practical Relevance. Developed numerical calculation method gives the possibility to perform high accuracy calculations of flows with strong non-stationary shock and detonation waves. At the same time, there are no non-physical solution oscillations on the shock wave front.

  16. Freedrop Testing and CFD Simulation of Ice Models from a Cavity into Supersonic Flow

    Science.gov (United States)

    2012-09-01

    flow in the test section. 9. Vacuum-side valve . Pilot actuated butterfly -type valve isolates vacuum condi- tions required to attain sub-atmospheric...dryers - DonaldsonrRegenerative Air Dryersrremove moisture from the compressed air prior to tunnel entry. 3. Pressure-side valve - El-O-Maticrpilot...actuator controls the high pressure sup- ply via a ball-type valve . 4. Regulating valve - Pressure controlled Leslierdiaphragm-type valve provides the

  17. Calculation of three-dimensional supersonic flow of a gas past a cube

    Science.gov (United States)

    Barausov, D. I.; Drobyshevskii, E. M.

    1991-09-01

    Flow of a nonviscous gas near the front face of a cube is investigated numerically using a second-order MacCormack scheme. Calculations are performed on a 40 x 32 x 32 grid using Godunov's finite difference scheme. The drag coefficient of a cube moving in air at Mach 20 is estimated at 1.7-1.8. The results of the study are relevant to the development of electrodynamic rail-gun launchers.

  18. The impact of viscosity on the morphology of gaseous flows in semidetached binary systems

    CERN Document Server

    Bisikalo, D V; Kuznetsov, O A; Chechetkin, V M

    2000-01-01

    Results of 3D gas dynamical simulation of mass transfer in binaries are presented for systems with various values of viscosity. Analysis of obtained solutions shows that in the systems with low value of viscosity the flow structure is qualitatively similar to one for systems with high viscosity. Presented calculations confirm that there is no shock interaction between the stream from L1 and the forming accretion disk (`hot spot') at any value of viscosity.

  19. A simple counter-flow cooling system for a supersonic free-jet beam source assembly.

    Science.gov (United States)

    Barr, M; Fahy, A; Martens, J; Dastoor, P C

    2016-05-01

    A simple design for an inexpensive, cooled, free-jet beam source is described. The source assembly features an integrated cooling system as supplied by a counter-flow of chilled nitrogen, and is composed primarily of off-the-shelf tube fittings. The design facilitates rapid implementation and eases subsequent alignment with respect to any downstream beamline aperture. The source assembly outlined cools the full length of the stagnation volume, offering temperature control down to 100 K and long-term temperature stability better than ±1 K.

  20. A simple counter-flow cooling system for a supersonic free-jet beam source assembly

    Energy Technology Data Exchange (ETDEWEB)

    Barr, M.; Fahy, A.; Martens, J.; Dastoor, P. C., E-mail: Paul.Dastoor@newcastle.edu.au [Centre for Organic Electronics, University of Newcastle, Callaghan, NSW 2308 (Australia)

    2016-05-15

    A simple design for an inexpensive, cooled, free-jet beam source is described. The source assembly features an integrated cooling system as supplied by a counter-flow of chilled nitrogen, and is composed primarily of off-the-shelf tube fittings. The design facilitates rapid implementation and eases subsequent alignment with respect to any downstream beamline aperture. The source assembly outlined cools the full length of the stagnation volume, offering temperature control down to 100 K and long-term temperature stability better than ±1 K.

  1. Numerical Solutions for Supersonic Flow of an Ideal Gas Around Blunt Two-Dimensional Bodies

    Science.gov (United States)

    Fuller, Franklyn B.

    1961-01-01

    The method described is an inverse one; the shock shape is chosen and the solution proceeds downstream to a body. Bodies blunter than circular cylinders are readily accessible, and any adiabatic index can be chosen. The lower limit to the free-stream Mach number available in any case is determined by the extent of the subsonic field, which in turn depends upon the body shape. Some discussion of the stability of the numerical processes is given. A set of solutions for flows about circular cylinders at several Mach numbers and several values of the adiabatic index is included.

  2. Experimental investigation on drag and heat flux reduction in supersonic/hypersonic flows: A survey

    Science.gov (United States)

    Wang, Zhen-guo; Sun, Xi-wan; Huang, Wei; Li, Shi-bin; Yan, Li

    2016-12-01

    The drag and heat reduction problem of hypersonic vehicles has always attracted the attention worldwide, and the experimental test approach is the basis of theoretical analysis and numerical simulation. In the current study, research progress of experimental investigations on drag and heat reduction are summarized by several kinds of mechanism, namely the forward-facing cavity, the opposing jet, the aerospike, the energy deposition and their combinational configurations, and the combinational configurations include the combinational opposing jet and forward-facing cavity concept and the combinational opposing jet and aerospike concept. The geometric models and flow conditions are emphasized, especially for the basic principle for the drag and heat flux reduction of each device. The measurement results of aerodynamic and aerothermodynamic are compared and analyzed as well, which can be a reference for assessing the accuracy of numerical results.

  3. A New Gaskinetic Model to Analyze Background Flow Effects on Weak Gaseous Jet Flows from Electric Propulsion Devices

    Directory of Open Access Journals (Sweden)

    Chunpei Cai

    2017-01-01

    Full Text Available Recent work on studying rarefied background and jet flow interactions is reported. A new gaskinetic method is developed to investigate two closely related problems. The first problem is how a collisionless background flow can affect a highly rarefied jet flow. The rarefied jet and background flow conditions are assumed available and described with seven parameters. Gaskinetic theories are applied and formulas are obtained for the mixture properties. Simulations are performed to validate these expressions, and excellent agreement is obtained. The second problem is to recover the collisionless background and jet flow parameters with limited measurements. A group of linearized equations are derived for the flowfield properties. The solving process includes initial estimations on the seven parameters, followed with iterations. Numerical tests are performed and the results indicate the procedure is accurate and efficient. The new method and expressions can reduce the amount of experimental work and numerical simulations to analyze facility effects. Parameter studies with particle simulations may require several months; however, the new methods may require minutes. These methods can be used to quantify and predict jet performance, vacuum chamber designs and optimization. Applications may be for many societies using vacuum conditions.

  4. Analysis of impact of general-purpose graphics processor units in supersonic flow modeling

    Science.gov (United States)

    Emelyanov, V. N.; Karpenko, A. G.; Kozelkov, A. S.; Teterina, I. V.; Volkov, K. N.; Yalozo, A. V.

    2017-06-01

    Computational methods are widely used in prediction of complex flowfields associated with off-normal situations in aerospace engineering. Modern graphics processing units (GPU) provide architectures and new programming models that enable to harness their large processing power and to design computational fluid dynamics (CFD) simulations at both high performance and low cost. Possibilities of the use of GPUs for the simulation of external and internal flows on unstructured meshes are discussed. The finite volume method is applied to solve three-dimensional unsteady compressible Euler and Navier-Stokes equations on unstructured meshes with high resolution numerical schemes. CUDA technology is used for programming implementation of parallel computational algorithms. Solutions of some benchmark test cases on GPUs are reported, and the results computed are compared with experimental and computational data. Approaches to optimization of the CFD code related to the use of different types of memory are considered. Speedup of solution on GPUs with respect to the solution on central processor unit (CPU) is compared. Performance measurements show that numerical schemes developed achieve 20-50 speedup on GPU hardware compared to CPU reference implementation. The results obtained provide promising perspective for designing a GPU-based software framework for applications in CFD.

  5. Heat flux reduction mechanism induced by a combinational opposing jet and cavity concept in supersonic flows

    Science.gov (United States)

    Huang, Wei; Jiang, Yan-ping; Yan, Li; Liu, Jun

    2016-04-01

    The thermal protection on the surface of hypersonic vehicles attracts an increasing attention worldwide, especially when the vehicle enters the atmosphere at high speed. In the current study, the Reynolds-averaged Navier-Stokes (RANS) equations coupled with the Menter's shear stress transport (SST) model have been employed to investigate the heat flux reduction mechanism induced by the variations of the cavity configuration, the jet pressure ratio and the injectant molecular weight in the combinational opposing jet and cavity concept. The length of the cavity is set to be 6 mm, 8 mm and 10 mm in order to make sure that the cavity configuration is the "open" cavity, and the jet pressure ratio is set to be 0.4, 0.6 and 0.8 in order to make sure that the flow field is steady. The injectant is set to be nitrogen and helium. The obtained results show that the aft angle of the cavity only has a slight impact on the heat flux reduction, and the heat flux peak decreases with the decrease of the length of the cavity. The design of the thermal protection system for the hypersonic blunt body is a multi-objective design exploration problem, and the heat flux distribution depends on the jet pressure ratio, the aft wall of the cavity and the injectant molecular weight. The heat flux peak decreases with the increase of the jet pressure ratio when the aft angle of the cavity is large enough, and this value is 45°.

  6. Gaseous emissions during the fattening of pigs kept either on fully slatted floors or on straw flow.

    Science.gov (United States)

    Philippe, F-X; Laitat, M; Canart, B; Vandenheede, M; Nicks, B

    2007-11-01

    The aim of this study was to compare the environmental impact of the straw-flow system for fattening pigs with the slatted-floor system by measuring pollutant gas emissions such as ammonia (NH3), nitrous oxide (N2O), methane (CH4) and carbon dioxide (CO2), manure nitrogen (N) content and emissions of water vapour (H2O). Three successive batches of 32 pigs were fattened. For each batch, pigs were allotted to two groups raised in separated rooms fitted either with a concrete totally slatted-floor system (0.75 m2 per pig) or with a straw-flow system (0.79 m2 per pig). With this last system, pigs were kept on a sloped floor, straw being provided daily at the top of the pen. Throughout the fattening period, about 34.4 kg of straw were supplied per pig. The straw, mixed with dung, travelled down the slope by pig motion and went out of the pen to a scraped passage. The solid fraction was scraped every day, stored in a heap in the room and removed every month, 1 week before each period of gaseous emission measurement. The liquid fraction was automatically pumped from the scraped passage into a hermetic tank, which was emptied at the end of each fattening period. Rooms were ventilated mechanically in order to maintain a constant ambient temperature. Once a month, the emissions of NH3, N2O, CH4, CO2 and H2O were measured hourly for 6 consecutive days via infrared photoacoustic detection. Mean daily emissions per pig fattened on the slatted floor or on the sloped floor were, respectively, 4.98 and 13.31 g NH3, 0.67 and 0.68 g N2O, 15.2 and 8.88 g CH4, 548 g and 406 g CO2 equivalents, 1.61 and 1.77 kg CO2 and 2.33 and 2.95 kg H2O. Except for N2O emissions, all the differences were statistically significant (P straw-flow system, solid manure amounted on average to 209 kg per pig and liquid manure to 53 kg per pig. The total N-content of the manure was 2.23 kg N per pig with the straw-flow system (solid and liquid manure) v. 3.26 kg N per pig for slurry from the slatted

  7. Ultra-high-speed digital in-line holography system applied to particle-laden supersonic underexpanded jet flows

    DEFF Research Database (Denmark)

    Ingvorsen, Kristian Mark; Buchmann, Nicolas A.; Soria, Julio

    2012-01-01

    for magnified digital in-line holography is created, using an ultra-high-speed camera capable of frame rates of up to 1.0MHz. To test the new technique an axisymmetric supersonic underexpanded particle-laden jet is investigated. The results show that the new technique allows for the acquisition of time resolved...

  8. Flow field analysis of aircraft configurations using a numerical solution to the three-dimensional unified supersonic/hypersonic small disturbance equations, part 1

    Science.gov (United States)

    Gunness, R. C., Jr.; Knight, C. J.; Dsylva, E.

    1972-01-01

    The unified small disturbance equations are numerically solved using the well-known Lax-Wendroff finite difference technique. The method allows complete determination of the inviscid flow field and surface properties as long as the flow remains supersonic. Shock waves and other discontinuities are accounted for implicity in the numerical method. This technique was programed for general application to the three-dimensional case. The validity of the method is demonstrated by calculations on cones, axisymmetric bodies, lifting bodies, delta wings, and a conical wing/body combination. Part 1 contains the discussion of problem development and results of the study. Part 2 contains flow charts, subroutine descriptions, and a listing of the computer program.

  9. The Design and Use of a Temperature-Compensated Hot-Film Anemometer System for Boundary-Layer Flow Transition Detection on Supersonic Aircraft

    Science.gov (United States)

    Chiles, Harry R.

    1988-01-01

    An airborne temperature-compensated hot-film anemometer system has been designed, fabricated, and used to obtain in-flight airfoil boundary-layer flow transition data by the NASA Ames-Dryden Flight Research Facility. Salient features of the anemometer include near constant sensitivity over the full flight envelope, installation without coaxial wiring, low-noise outputs, and self-contained signal conditioning with dynamic and steady-state outputs. The small size, low-power dissipation, and modular design make the anemometer suitable for use in modern high-performance research aircraft. Design of the temperature-compensated hot-film anemometer and its use for flow transition detection on a laminar flow flight research project are described. Also presented are data gathered in flight which is representative of the temperature-compensated hot-film anemometer operation at subsonic, transonic, and supersonic flight conditions.

  10. Nonlinear Dynamical Friction in a Gaseous Medium

    CERN Document Server

    Kim, Hyosun

    2009-01-01

    Using high-resolution, two-dimensional hydrodynamic simulations, we investigate nonlinear gravitational responses of gas to, and the resulting drag force on, a very massive perturber M_p moving at velocity V_p through a uniform gaseous medium of adiabatic sound speed a_0. We model the perturber as a Plummer potential with softening radius r_s, and run various models with differing A=GM_p/(a_0^2 r_s) and M=V_p/a_0 by imposing cylindrical symmetry with respect to the line of perturber motion. For supersonic cases, a massive perturber quickly develops nonlinear flows that produce a detached bow shock and a vortex ring, which is unlike in the linear cases where Mach cones are bounded by low-amplitude Mach waves. The flows behind the shock are initially non-steady, displaying quasi-periodic, overstable oscillations of the vortex ring and the shock. The vortex ring is eventually shed downstream and the flows evolve toward a quasi-steady state where the density wake near the perturber is in near hydrostatic equilibr...

  11. Gaseous Matter

    CERN Document Server

    Angelo, Joseph A

    2011-01-01

    aseous Matter focuses on the many important discoveries that led to the scientific interpretation of matter in the gaseous state. This new, full-color resource describes the basic characteristics and properties of several important gases, including air, hydrogen, helium, oxygen, and nitrogen. The nature and scope of the science of fluids is discussed in great detail, highlighting the most important scientific principles upon which the field is based. Chapters include:. Gaseous Matter An Initial Perspective. Physical Characteristics of Gases. The Rise of the Science of Gases. Kinetic Theory of

  12. Supersonic induction plasma jet modeling

    Energy Technology Data Exchange (ETDEWEB)

    Selezneva, S.E. E-mail: svetlana2@hermes.usherbS_Selezneva2@hermes.usherb; Boulos, M.I

    2001-06-01

    Numerical simulations have been applied to study the argon plasma flow downstream of the induction plasma torch. It is shown that by means of the convergent-divergent nozzle adjustment and chamber pressure reduction, a supersonic plasma jet can be obtained. We investigate the supersonic and a more traditional subsonic plasma jets impinging onto a normal substrate. Comparing to the subsonic jet, the supersonic one is narrower and much faster. Near-substrate velocity and temperature boundary layers are thinner, so the heat flux near the stagnation point is higher in the supersonic jet. The supersonic plasma jet is characterized by the electron overpopulation and the domination of the recombination over the dissociation, resulting into the heating of the electron gas. Because of these processes, the supersonic induction plasma permits to separate spatially different functions (dissociation and ionization, transport and deposition) and to optimize each of them. The considered configuration can be advantageous in some industrial applications, such as plasma-assisted chemical vapor deposition of diamond and polymer-like films and in plasma spraying of nanoscaled powders.

  13. On-line gaseous formaldehyde detection by a microfluidic analytical method based on simultaneous uptake and derivatization in a temperature controlled annular flow.

    Science.gov (United States)

    Guglielmino, Maud; Bernhardt, Pierre; Trocquet, Claire; Serra, Christophe A; Le Calvé, Stéphane

    2017-09-01

    This paper is focused on the improvement of a microfluidic analytical method for the detection of low airborne formaldehyde concentrations, based on only two distinct steps permitting to reduce the response time and to improve the compactness of the device. First, gaseous formaldehyde is trapped into an acetylacetone solution at 65°C through an annular liquid/gas flow and reacts immediately to form 3,5-Diacetyl-1,4-dihydrolutidine which is then quantified by colorimetry using a liquid core waveguide (LCW). To obtain an annular flow, 3 different hydrophilic silica capillaries of 320, 450 and 530µm ID were tested and the corresponding phase diagrams were obtained in the ranges of liquid and gas flows of 5-35µLmin(-1) and 5-35mLmin(-1) respectively. Finally, the analytical performances were determined using the lowest flow values of 5µLmin(-1) and 5NmLmin(-1), ensuring an annular flow and increasing the microdevice autonomy. If the uptake yield of gaseous formaldehyde into the solution was close to 100%, only the 530µm ID capillary permits to obtain a reaction time long enough for a full conversion of formaldehyde into 3,5-Diacetyl-1,4-dihydrolutidine. With a LCW pathlength of 5cm, the microdevice response was perfectly linear in the range 0-154µgm(-3) with a detection limit of 1.8µgm(-3). Copyright © 2017 Elsevier B.V. All rights reserved.

  14. Anomalous argon excitation in pulse supersonic flows of Ar + CH sub 4 , Ar + SiH sub 4 and Ar + CH sub 4 + SiH sub 4 mixtures, activated with an electron beam

    CERN Document Server

    Madirbaev, V Z; Korobejshchikov, N G; Sharafutdinov, R G

    2001-01-01

    The processes of energy exchange in the supersonic flows of the argon mixtures with methane and silane, activated by the electron beam, are studied. It is shown, that at the initial stage of condensation in the flux there takes place selective excitation of the argon atoms energy levels. The boundary parameters, whereby the effect of the anomalous radiation excitation is observed, are determined

  15. Existence of shocklets in a two-dimensional supersonic mixing layer and its influence on the flow structure

    Institute of Scientific and Technical Information of China (English)

    2001-01-01

    The spatial evolution of a T-S wave and its subharmonic wave, introduced at the inlet in a 2-D supersonic mixing layer, was investigated by using DNS. The relationship between the amplitude of the disturbance wave and the strength of the shocklet caused by the disturbance was investigated. We analyzed the shape of the disturbance velocity profile on both sides of the shocklet, and found that the existence of shocklet affected appreciably the disturbance velocity. The effects on the high speed side and low speed side of the mixing layer were found to be different.

  16. Experiments on free and impinging supersonic microjets

    Energy Technology Data Exchange (ETDEWEB)

    Phalnikar, K.A.; Kumar, R.; Alvi, F.S. [Florida A and M University and Florida State University, Department of Mechanical Engineering, Tallahassee, FL (United States)

    2008-05-15

    The fluid dynamics of microflows has recently commanded considerable attention because of their potential applications. Until now, with a few exceptions, most of the studies have been limited to low speed flows. This experimental study examines supersonic microjets of 100-1,000 {mu}m in size with exit velocities in the range of 300-500 m/s. Such microjets are presently being used to actively control larger supersonic impinging jets, which occur in STOVL (short takeoff and vertical landing) aircraft, cavity flows, and flow separation. Flow properties of free as well as impinging supersonic microjets have been experimentally investigated over a range of geometric and flow parameters. The flowfield is visualized using a micro-schlieren system with a high magnification. These schlieren images clearly show the characteristic shock cell structure typically observed in larger supersonic jets. Quantitative measurements of the jet decay and spreading rates as well as shock cell spacing are obtained using micro-pitot probe surveys. In general, the mean flow features of free microjets are similar to larger supersonic jets operating at higher Reynolds numbers. However, some differences are also observed, most likely due to pronounced viscous effects associated with jets at these small scales. Limited studies of impinging microjets were also conducted. They reveal that, similar to the behavior of free microjets, the flow structure of impinging microjets strongly resembles that of larger supersonic impinging jets. (orig.)

  17. Experiments on free and impinging supersonic microjets

    Science.gov (United States)

    Phalnikar, K. A.; Kumar, R.; Alvi, F. S.

    2008-05-01

    The fluid dynamics of microflows has recently commanded considerable attention because of their potential applications. Until now, with a few exceptions, most of the studies have been limited to low speed flows. This experimental study examines supersonic microjets of 100-1,000 μm in size with exit velocities in the range of 300-500 m/s. Such microjets are presently being used to actively control larger supersonic impinging jets, which occur in STOVL (short takeoff and vertical landing) aircraft, cavity flows, and flow separation. Flow properties of free as well as impinging supersonic microjets have been experimentally investigated over a range of geometric and flow parameters. The flowfield is visualized using a micro-schlieren system with a high magnification. These schlieren images clearly show the characteristic shock cell structure typically observed in larger supersonic jets. Quantitative measurements of the jet decay and spreading rates as well as shock cell spacing are obtained using micro-pitot probe surveys. In general, the mean flow features of free microjets are similar to larger supersonic jets operating at higher Reynolds numbers. However, some differences are also observed, most likely due to pronounced viscous effects associated with jets at these small scales. Limited studies of impinging microjets were also conducted. They reveal that, similar to the behavior of free microjets, the flow structure of impinging microjets strongly resembles that of larger supersonic impinging jets.

  18. Experimental comparison of two hot-wire techniques for resolution of turbulent mass flux and local stagnation temperature in supersonic flow

    Science.gov (United States)

    Walker, D. A.; Ng, W. F.; Walker, M. D.

    1988-01-01

    The performance of two constant-temperature normal hot-wire techniques in a supersonic flow is examined. The first technique uses a single-wire and rapid scanning of multiple overheat ratios. Time averages of the signals at all overheats are used to separate the mean and rms mass flux, stagnation temperature and their cross-correlation. The second technique uses a dual-wire probe with each wire operating at different overheat ratios, giving instantaneous mass flux and stagnation temperature. Preliminary results indicate that the separation distance (0.18 mm) between the two hot wires in the dual-wire probe does not introduce significant error. However, the rms mass flux inferred from the dual-wire technique is a factor of two higher than that from the single-wire technique.

  19. Mixing in Supersonic Turbulence

    CERN Document Server

    Pan, Liubin

    2010-01-01

    In many astrophysical environments, mixing of heavy elements occurs in the presence of a supersonic turbulent velocity field. Here we carry out the first systematic numerical study of such passive scalar mixing in isothermal supersonic turbulence. Our simulations show that the ratio of the scalar mixing timescale, $\\tau_{\\rm c}$, to the flow dynamical time, $\\tau_{\\rm dyn}$ (defined as the flow driving scale divided by the rms velocity), increases with the Mach number, $M$, for $M \\lsim3$, and becomes essentially constant for $M \\gsim3.$ This trend suggests that compressible modes are less efficient in enhancing mixing than solenoidal modes. However, since the majority of kinetic energy is contained in solenoidal modes at all Mach numbers, the overall change in $\\tau_{\\rm c}/\\tau_{\\rm dyn}$ is less than 20\\% over the range $1 \\lsim M \\lsim 6$. At all Mach numbers, if pollutants are injected at around the flow driving scale, $\\tau_{\\rm c}$ is close to $\\tau_{\\rm dyn}.$ This suggests that scalar mixing is drive...

  20. 三组分混合物超音速凝结机理%Condensation mechanism of the ternary mixture in supersonic flows

    Institute of Scientific and Technical Information of China (English)

    蒋文明; 刘中良; 刘杨

    2012-01-01

    The supersonic condensation process of a ternary mixture, including methane, water vapor and nonane, in a nozzle was studied in order to understand the condensation mechanism, nucleation and droplet growth rules of water vapor and heavy hydrocarbons from natural gas mixture. Firstly, based on the existing mathematic model of the two-component mixture supersonic condensation and combined with the latest research results at home and abroad, a physical model for the condensation process of the ternary mixture in supersonic flows was built. Secondly, a mathematic model of the ternary mixture supersonic condensation was built and applied in analog computation according to simulation results of the two-component mixture supersonic condensation. The result showed that in the ternary mixture, water vapor begins to condensate spontaneously prior to nonane vapor (x = 4. 0 mm), forming droplets to serve as allochthonous nuclei for nonane vapor condensation and lowering the free energy barrier of nonane vapor. Consequently, nonane vapor begins to condensate at a lower subcooling (38. 3 K) and supersaturation (37. 4). In other words, the occurrence of water vapor in a sense accelerates the condensation process of nonane vapor.%为了解天然气混合物中水蒸气、重烃在喷管内的凝结机理,明确其液滴成核与液滴生长的基本规律,研究了甲烷-水蒸气-壬烷三组分混合物在喷管内的超音速凝结过程.首先在已有双组分混合物超音速凝结数学模型的基础上,结合国外最新研究成果,建立了三组分混合物在喷管内的超音速凝结过程物理模型;然后根据双组分混合物的超音速凝结模拟结果,建立了三组分混合物在喷管内的超音速凝结过程数学模型并进行了模拟计算.结果表明,在甲烷-水蒸气-壬烷混合物中,水蒸气较早出现自发凝结现象(x=4.0 mm),并且形成的水滴充当了壬烷蒸气发生凝结的外界核心,降低了壬烷蒸气发生凝结

  1. Artificial dissipation models applied to Navier-Stokes equations for analysis of supersonic flow of helium gas around a geometric configuration ramp type

    Energy Technology Data Exchange (ETDEWEB)

    Rocha, Jussie Soares da, E-mail: jussie.soares@ifpi.edu.br [Instituto Federal de Educacao, Ciencia e Tecnologia do Piaui (IFPI), Valenca, PI (Brazil); Maciel, Edisson Savio de G., E-mail: edissonsavio@yahoo.com.br [Instituto Tecnologico de Aeronautica (ITA), Sao Paulo, SP (Brazil); Lira, Carlos A.B. de O., E-mail: cabol@ufpe.edu.br [Universidade Federal de Pernambuco (UFPE), Recife, PE (Brazil)

    2015-07-01

    Very High Temperature Gas Cooled Reactors - VHTGRs are studied by several research groups for the development of advanced reactors that can meet the world's growing energy demand. The analysis of the flow of helium coolant around the various geometries at the core of these reactors through computational fluid dynamics techniques is an essential tool in the development of conceptual designs of nuclear power plants that provide added safety. This analysis suggests a close analogy with aeronautical cases widely studied using computational numerical techniques to solve systems of governing equations for the flow involved. The present work consists in solving the Navier-Stokes equations in a conservative form, in two-dimensional space employing a finite difference formulation for spatial discretization using the Euler method for explicit marching in time. The physical problem of supersonic laminar flow of helium gas along a ramp configuration is considered. For this, the Jameson and Mavriplis algorithm and the artificial dissipations models linear and nonlinear of Pulliam was implemented. A spatially variable time step is employed aiming to accelerate the convergence to the steady state solution. The main purpose of this work is to study the cited dissipation models and describe their characteristics in relation to the overall quality of the solution, aiming preliminary results for the development of computational tools of dynamic analysis of helium flow for the VHTGR core. (author)

  2. Effect of rod gap spacing on a suction panel for laminar flow and noise control in supersonic wind tunnels. M.S. Thesis - Old Dominion Univ.

    Science.gov (United States)

    Harvey, W. D.

    1975-01-01

    Results are presented of a coordinated experimental and theoretical study of a sound shield concept which aims to provide a means of noise reduction in the test section of supersonic wind tunnels at high Reynolds numbers. The model used consists of a planar array of circular rods aligned with the flow, with adjustable gaps between them for boundary layer removal by suction, i.e., laminar flow control. One of the basic requirements of the present sound shield concept is to achieve sonic cross flow through the gaps in order to prevent lee-side flow disturbances from penetrating back into the shielded region. Tests were conducted at Mach 6 over a local unit Reynolds number range from about 1.2 x 10 to the 6th power to 13.5 x 10 to the 6th power per foot. Measurements of heat transfer, static pressure, and sound levels were made to establish the transition characteristics of the boundary layer on the rod array and the sound shielding effectiveness.

  3. Computational study and error analysis of an integrated sampling-probe and gas-analyzer for mixing measurements in supersonic flow

    Science.gov (United States)

    Zhu, Wenbo; Ground, Cody; Maddalena, Luca; Viti, Valerio

    2016-09-01

    Concentration probes are employed in supersonic flow mixing measurements. Because the typical design of such probes is essentially based on an inviscid, adiabatic, quasi-1D analysis, the scope of this work is to understand better and quantify the severe impact of viscous effects on the probe’s internal gasdynamics and the associated uncertainties in the measured quantities via a computational fluid dynamics analysis. Specifically, the focus is on the augmented errors due to the aforementioned viscous effects when coupled with various cases of probe-flow misalignment, which is a typical scenario encountered in mixing measurements of binary gas compositions (air and helium in the present work) in vortex-dominated flows. Results show phenomena such as shock induced boundary layer separation and the formation of an oblique shock train. These flow features are found to noticeably affect the accuracy of the composition measurement. The errors associated with the inviscid, adiabatic, quasi-1D analysis of the probes are quantified in this study.

  4. The Marriage of Spectroscopy and Dynamics: Chirped-Pulse Fourier-Transform Mm-Wave Cp-Ft Spectroscopy in Pulsed Uniform Supersonic Flows

    Science.gov (United States)

    Abeysekera, Chamara; Oldham, James M.; Suits, Arthur G.; Park, G. Barratt; Field, Robert W.

    2012-06-01

    A new experimental scheme is presented that combines two powerful emerging technologies: chirped-pulse Fourier-transform mm-Wave spectroscopy and pulsed uniform supersonic flows. It promises a nearly universal detection method that can deliver quantitative isomer, conformer, and vibrational level specific detection, characterization of unstable reaction products and intermediates, and perform unique spectroscopic, kinetics, and dynamics measurements. Chirped-pulse Fourier-transform microwave (CP-FTMW) spectroscopy, pioneered by Pate and coworkers, allows rapid acquisition of broadband microwave spectrum through advancements in waveform generation and oscilloscope technology. This revolutionary approach has successfully been adapted to higher frequencies by the Field group at MIT. Our new apparatus will exploit amplified chirped pulses in the range of 26-40 GHz, in combination with a pulsed uniform supersonic flow from a Laval nozzle. This nozzle source, pioneered by Rowe, Sims, and Smith for low temperature kinetics studies, produces thermalized reactants at high densities and low temperatures perfectly suitable for reaction dynamics experiments studied using the CP-mmW approach. This combination of techniques shall enhance the thousand-fold improvement in data acquisition rate achieved in the CP method by a further 2-3 orders of magnitude. A pulsed flow alleviates the challenges of continuous uniform flow, e.g. large gas loads and reactant consumption rates. In contrast to other pulsed Laval systems currently in use, we will use a fast piezo valve and small chambers to achieve the desired pressures while minimizing the gas load, so that a 10 Hz repetition rate can be achieved with one turbomolecular pump. The proposed technique will be suitable for many diverse fields, including fundamental studies in spectroscopy and reaction dynamics, reaction kinetics, combustion, atmospheric chemistry, and astrochemistry. We expect a significant advancement in the ability to

  5. Numerical Research on Detonation Wave Characteristic in High Temperature Supersonic Flow%高温超声速流中爆震波特性数值研究

    Institute of Scientific and Technical Information of China (English)

    黄思源; 桂业伟; 白菡尘

    2012-01-01

    通过对高温超声速流中爆震波性质的研究,评估其在高超声速冲压发动机燃烧室的燃烧组织中应用的可行性,并通过数值模拟对分析结论进行了验证。提出了一种新的爆震波起爆机制,注入高温超声速流中的燃料混气可通过自身缓慢的释热使流动进入局域热壅塞状态,进而借助局域热壅塞产生的激波实现爆震波的起爆。计算结果表明在适宜的温度与马赫数条件下,注入高温超声速流中的燃料可通过新的起爆机制在超声速流中形成一道稳定的驻定爆震波。表明在高超声速冲压发动机燃烧室中存在着通过驻定爆震波实现火焰稳定的可能性。%To evaluate the feasibility for utilizing the detonation wave to stabilize flame in scramjet combustor,the detona- tion wave characteristic in high temperature environment was studied by numerical simulations. A new initiation mechanism of detonation was presented. The premixed gas injected into high temperature supersonic flow can reach local thermal choking state through the heat released by slow reaction of premixed fuel gas and then a detonation wave can be initiated by shock pro- duced in thermal choking state. The numerical results show that the fuel injected into high temperature supersonic flow can form a standing detonation wave by the new mechanism in some special temperature and Mach number flow conditions. The re- search shows that it is possible utilizing the standing detonation wave to stabilize flame in scramjet combustor.

  6. Pdf prediction of supersonic hydrogen flames

    Science.gov (United States)

    Eifler, P.; Kollmann, W.

    1993-01-01

    A hybrid method for the prediction of supersonic turbulent flows with combustion is developed consisting of a second order closure for the velocity field and a multi-scalar pdf method for the local thermodynamic state. It is shown that for non-premixed flames and chemical equilibrium mixture fraction, the logarithm of the (dimensionless) density, internal energy per unit mass and the divergence of the velocity have several advantages over other sets of scalars. The closure model is applied to a supersonic non-premixed flame burning hydrogen with air supplied by a supersonic coflow and the results are compared with a limited set of experimental data.

  7. PIV Validation of 3D Multicomponent Model for Cold Spray Within Nitrogen and Helium Supersonic Flow Field

    Science.gov (United States)

    Faizan-Ur-Rab, M.; Zahiri, S. H.; Masood, S. H.; Jahedi, M.; Nagarajah, R.

    2017-06-01

    This study presents the validation of a developed three-dimensional multicomponent model for cold spray process using two particle image velocimetry (PIV) experiments. The k- ɛ type 3D model developed for spherical titanium particles was validated with the measured titanium particle velocity within a nitrogen and helium supersonic jet. The 3D model predicted lower values of particle velocity than the PIV experimental study that used irregularly shaped titanium particles. The results of the 3D model were consistent with the PIV experiment that used spherical titanium powder. The 3D model simulation of particle velocity within the helium and nitrogen jet was coupled with an estimation of titanium particle temperature. This was achieved with the consideration of the fact that cold spray particle temperature is difficult and expensive to measure due to considerably lower temperature of particles than thermal spray. The model predicted an interesting pattern of particle size distribution with respect to the location of impact with a concentration of finer particles close to the jet center. It is believed that the 3D model outcomes for particle velocity, temperature and location could be a useful tool to optimize system design, deposition process and mechanical properties of the additively manufactured cold spray structures.

  8. THE SEPARATION OF URANIUM ISOTOPES BY GASEOUS DIFFUSION: A LINEAR PROGRAMMING MODEL,

    Science.gov (United States)

    URANIUM, ISOTOPE SEPARATION), (*GASEOUS DIFFUSION SEPARATION, LINEAR PROGRAMMING ), (* LINEAR PROGRAMMING , GASEOUS DIFFUSION SEPARATION), MATHEMATICAL MODELS, GAS FLOW, NUCLEAR REACTORS, OPERATIONS RESEARCH

  9. Supersonic flow with shock waves. Monte-Carlo calculations for low density plasma. I; Flujo supersonico de un plasma con ondas de choque, un metodo de montecarlo para plasmas de baja densidad, I.

    Energy Technology Data Exchange (ETDEWEB)

    Almenara, E.; Hidalgo, M.; Saviron, J. M.

    1980-07-01

    This Report gives preliminary information about a Monte Carlo procedure to simulate supersonic flow past a body of a low density plasma in the transition regime. A computer program has been written for a UNIVAC 1108 machine to account for a plasma composed by neutral molecules and positive and negative ions. Different and rather general body geometries can be analyzed. Special attention is played to tho detached shock waves growth In front of the body. (Author) 30 refs.

  10. A Karhunen-Loève least-squares technique for optimization of geometry of a blunt body in supersonic flow

    Science.gov (United States)

    Brooks, Gregory P.; Powers, Joseph M.

    2004-03-01

    A novel Karhunen-Loève (KL) least-squares model for the supersonic flow of an inviscid, calorically perfect ideal gas about an axisymmetric blunt body employing shock-fitting is developed; the KL least-squares model is used to accurately select an optimal configuration which minimizes drag. Accuracy and efficiency of the KL method is compared to a pseudospectral method employing global Lagrange interpolating polynomials. KL modes are derived from pseudospectral solutions at Mach 3.5 from a uniform sampling of the design space and subsequently employed as the trial functions for a least-squares method of weighted residuals. Results are presented showing the high accuracy of the method with less than 10 KL modes. Close agreement is found between the optimal geometry found using the KL model to that found from the pseudospectral solver. Not including the cost of sampling the design space and building the KL model, the KL least-squares method requires less than half the central processing unit time as the pseudospectral method to achieve the same level of accuracy. A decrease in computational cost of several orders of magnitude as reported in the literature when comparing the KL method against discrete solvers is shown not to hold for the current problem. The efficiency is lost because the nature of the nonlinearity renders a priori evaluation of certain necessary integrals impossible, requiring as a consequence many costly reevaluations of the integrals.

  11. Investigation on subsonic to supersonic flow around a sphere at low Reynolds number of between 50 and 300 by direct numerical simulation

    Science.gov (United States)

    Nagata, T.; Nonomura, T.; Takahashi, S.; Mizuno, Y.; Fukuda, K.

    2016-05-01

    In this study, analysis of flow properties around a sphere and its aerodynamic coefficients in the high-Mach-and-low-Reynolds-numbers conditions is carried out by direct numerical simulations solving the three-dimensional compressible Navier-Stokes equations. The calculation is performed on a boundary-fitted coordinate system with a high-order scheme of sufficient accuracy. The analysis is conducted by assuming a rigid sphere with a Reynolds number of between 50 and 300, based on the diameter of the sphere and the freestream velocity and a freestream Mach number of between 0.3 and 2.0, together with the adiabatic wall boundary condition. The calculation shows the following yields: (1) unsteady fluctuation of hydrodynamic forces become smaller as the Mach number increases under the same Reynolds number condition, (2) the drag coefficient increases with the Mach number due to an increase in the pressure drag by the shock wave, and (3) an accurate prediction of the drag coefficient in the supersonic regime using traditional models might be difficult.

  12. 在超音速压缩角下的湍流模型数值比较%Comparison of Turbulent Models for Supersonic Compression Corner Flow

    Institute of Scientific and Technical Information of China (English)

    胡李鹏; 苏莫明; 孙正中; 李小平

    2009-01-01

    在超音速飞机进气道的湍流数值仿真中,选择合适的湍流模型可以比较准确的捕捉激波位置和流场分布,对飞机发动机的设计和控制都是很重要的.但是对湍流模型的选择,文献中并无记载.针对上述情况选择了进气道的简化结构.分别运用标准的高雷诺数k-epsilon模型,重整化群RNG模型,Realizable k-epsilon模型及ASM模型等进行了数值仿真和比较.基于SIMPLE算法,采用相同的分析壁面函数处理法,并且对流项都采用MINMOD格式.从比较发现:RNG模型比标准的k-epsilon模型和Realizable k-epsilon模型精度高,比ASM模型精度稍低,但是比ASM模型省时间,最后作者认为RNG模型在算例中是最经济实用的湍流模型.%A decent turbulence model in the numerical simulation of supersonic inlet can precisely capture the shock wave and predict the flow field, which is very important to the design and control of aircraft engine. However, no reference deals with the selection of turbulence model under this condition, so a comparison of turbulent models is performed on the supersonic compression corner which is a similar and simple configuration of inlet channel. The four turbulent models are standard k -epsilon model, RNG model , Realizable model and ASM model. They depend on the same SIMPLE algorithm ,analytical wall function and MINMOD scheme of convection. The paper concludes that the RNG turbulent model is more precise than the standard k -epsilon model and the Realizable k -epsilon model, and needs less time than ASM model . In the end , the it is concluded that the RNG model is the most economic and practical one.

  13. Simultaneous measurements of temperature, density, and pressure in a supersonic turbulent flow using laser-induced fluorescence

    Science.gov (United States)

    Mckenzie, R. L.; Gross, K. P.; Logan, P.

    1985-01-01

    A pulsed laser-induced fluorescence technique is described that provides simultaneous measurements of temperature, density, and pressure in low-temperature, turbulent flows. The measurements are made with spatial and temporal resolution comparable to that obtained with modern laser anemometer techniques used for turbulent boundary layer research. The capabilities of the method are briefly described and its demonstration in a simple two-dimensional turbulent boundary layer at Mach 2 is reported. The results are compared with conventional hot-wire anemometer data obtained in the same flow.

  14. Numerical analysis for supersonic turbulent mixing layers of different species gases. lst report. ; Mixing characteristics of uniform flows. Choonsoku ishu gas ranryu kongoso no suchi kaiseki. 1. ; Ichiyoryu no kongo tokusei

    Energy Technology Data Exchange (ETDEWEB)

    Nakano, S.; Ikegawa, M. (Hitachi Ltd., Tokyo (Japan))

    1990-07-25

    Flow field in which two supersonic turbulent flows with different species gases mix, was analyzed with a two-equation turbulence model and the mixing characteristics of 2 supersonic parallel flows were investigated by making the inlet flow condition of high speed gas constant and by ststematically changing the inlet flow condition of low speed gas. When mixing is carried out so that high speed gas is taken in the low speed gas, high spreading rate of the mixing layer is obtained and this tendency is emphasized markedly as the ratio such as velocity, density and pressure between low and high speed gases become small. The spreading of low mass ratio layer of low speed gas and that of low mass ratio layer of high speed gas are assymmetric and the spreading of the former is suppressed at the coindition where the latter expands. The tendency of developing rate of mixing layer to the correlating parameter in this calculation agreed well with results of visualized experiment. 14 refs., 10 figs., 3 tabs.

  15. Design features of a low-disturbance supersonic wind tunnel for transition research at low supersonic Mach numbers

    Science.gov (United States)

    Wolf, Stephen W. D.; Laub, James A.; King, Lyndell S.; Reda, Daniel C.

    1992-01-01

    A unique, low-disturbance supersonic wind tunnel is being developed at NASA-Ames to support supersonic laminar flow control research at cruise Mach numbers of the High Speed Civil Transport (HSCT). The distinctive design features of this new quiet tunnel are a low-disturbance settling chamber, laminar boundary layers along the nozzle/test section walls, and steady supersonic diffuser flow. This paper discusses these important aspects of our quiet tunnel design and the studies necessary to support this design. Experimental results from an 1/8th-scale pilot supersonic wind tunnel are presented and discussed in association with theoretical predictions. Natural laminar flow on the test section walls is demonstrated and both settling chamber and supersonic diffuser performance is examined. The full-scale wind tunnel should be commissioned by the end of 1993.

  16. Investigation of nonlinear turbulence models for separated supersonic flows%超声速分离流非线性湍流模式的研究

    Institute of Scientific and Technical Information of China (English)

    杨晓东; 马晖扬

    2002-01-01

    本文在低雷诺数k-ε两方程框架下,应用八个常见的非线性湍流模式,对两个激波/边界层相互作用诱导分离的超声速流动进行了研究.采用的非线性模式有:二阶模式(Wilcox & Rubesin (1980), Shih, Zhu & Lumley (1993), Shih, Zhu & Lumley (1995), Gatski & Speziale (1993))和三阶模式(Craft, Launder & Suga (1996), Lien & Leschziner (1996), Apsley & Leschziner (1998), Shih (1997)).两个超声速流动为:20°可压缩拐角绕流和轴对称尖顶拱-柱-裙组合体绕流.计算结果表明,对于激波边界层相互作用,在不做任何可压缩性修正的情况下,非线性模式并没有给出明显优于线性模式的结果.%Eight popular nonlinear turbulence models under low-Re k-ε framework have been tested and validated against experimental data of two supersonic flows with shock-wave/ boundary-layer interaction including separation. These models are: the nonlinear quadratic models ( Wilcox & Rubesin (1980), Shih, Zhu & Lumley (1993), Shih, Zhu & Lumley (1995), Gatski & Speziale (1993) ) and the nonlinear cubic models ( Craft, Launder & Suga (1996), Lien & Leschziner (1996), Apsley & Leschziner (1998), Shih (1997) ). The configurations consist of a 20°compression corner and an axisymmetric ogive-cylinder-flare. The computational results show that nonlinear models yield little improvement over linear models without any compressibility correction.

  17. 高速PIV布撒技术的改进研究%Research on Improving Technique of PIV Seeding in Hyper/supersonic Flow

    Institute of Scientific and Technical Information of China (English)

    王新元

    2014-01-01

    Based on the developed technique of Hypersonic Innovation Technique Laboratory of SJTU, the new PIV seeding system in hyper/supersonic flow is developed and improved.The new PIV seeding system is redesigned by im-proving the conduit,high pressure gas source and nozzle to overcome the instability of effective seeding of the old sys-tem. Flexibility of conduit,high press dry nitrogen and turbulence nozzle are used to reconstruct the system. The recon-struction was analyzed and experimentally tested, which shows that seeding effect is improved. At last, more directions to improve the system are offered.%基于上海交通大学高超创新实验室现有技术,为发展高速PIV技术而改进开发了高速PIV粒子布撒系统。针对原有系统经常无法有效布撒粒子的缺陷,从系统中的管道、高压气体、喷嘴等几个方向下手进行改造,设计了新的高速PIV粒子布撒系统。对管道进行了软管化设计,高压气体采用干燥的氮气,喷嘴则设计成能在罐体中产生旋流的结构。对于这些改造进行了分析和实验测试,证明了这些改造能加强布撒粒子的效果。最后提出了这套系统可以继续改进的一些方向。

  18. Supersonic Injection of Aerated Liquid Jet

    Science.gov (United States)

    Choudhari, Abhijit; Sallam, Khaled

    2016-11-01

    A computational study of the exit flow of an aerated two-dimensional jet from an under-expanded supersonic nozzle is presented. The liquid sheet is operating within the annular flow regime and the study is motivated by the application of supersonic nozzles in air-breathing propulsion systems, e.g. scramjet engines, ramjet engines and afterburners. The simulation was conducted using VOF model and SST k- ω turbulence model. The test conditions included: jet exit of 1 mm and mass flow rate of 1.8 kg/s. The results show that air reaches transonic condition at the injector exit due to the Fanno flow effects in the injector passage. The aerated liquid jet is alternately expanded by Prandtl-Meyer expansion fan and compressed by oblique shock waves due to the difference between the back (chamber) pressure and the flow pressure. The process then repeats itself and shock (Mach) diamonds are formed at downstream of injector exit similar to those typical of exhaust plumes of propulsion system. The present results, however, indicate that the flow field of supersonic aerated liquid jet is different from supersonic gas jets due to the effects of water evaporation from the liquid sheet. The contours of the Mach number, static pressure of both cases are compared to the theory of gas dynamics.

  19. Simulating Supersonic Turbulence in Galaxy Outflows

    CERN Document Server

    Scannapieco, Evan

    2010-01-01

    We present three-dimensional, adaptive mesh simulations of dwarf galaxy out- flows driven by supersonic turbulence. Here we develop a subgrid model to track not only the thermal and bulk velocities of the gas, but also its turbulent velocities and length scales. This allows us to deposit energy from supernovae directly into supersonic turbulence, which acts on scales much larger than a particle mean free path, but much smaller than resolved large-scale flows. Unlike previous approaches, we are able to simulate a starbursting galaxy modeled after NGC 1569, with realistic radiative cooling throughout the simulation. Pockets of hot, diffuse gas around individual OB associations sweep up thick shells of material that persist for long times due to the cooling instability. The overlapping of high-pressure, rarefied regions leads to a collective central outflow that escapes the galaxy by eating away at the exterior gas through turbulent mixing, rather than gathering it into a thin, unstable shell. Supersonic, turbul...

  20. [Unsegmented continuous-flow sample processing and electrochemical detection of gaseous species]. Final report, March 1, 1985--February 28, 1991

    Energy Technology Data Exchange (ETDEWEB)

    Mottola, H.A.

    1991-12-31

    Goals were a continuous-flow, unsegmented, all-gas carrier and/or a segmented liquid/gas interface system for sample introduction and transport to detection/determination point; a regenerable electrode probe base on redox reactions of Fe(II) and Fe(III) complexes with 1, 10-phenanthroline and related ligands; and amperometric/coulometric current measurements providing analyte signals. Gases to be detected included NO{sub x} and SO{sub 2}. This report is divided into 3 parts: preparation of new ligands of 1,10-phenanthroline family; glassy carbon surfaces coated with polymeric films prepared from monomeric units of tris[5-amino-1,10-phenanthroline]iron(II); and sulfite oxidase/hexacyanoferrate modified C paste electrode.

  1. Computational Study of the Supersonic Ejector Flows with a V-shape Nozzle%V形喷嘴的超声速引射器的数值模拟

    Institute of Scientific and Technical Information of China (English)

    孔凡实; 崔宝玲; 金英子; 金羲东

    2013-01-01

    To improve the performance of supersonic ejector,this paper redesigns a new V-shape nozzle based on the experimental result of the original convergent nozzle; makes it introduce more vortexes,thus improving the drainage flow by changing the number of lobes of V-shape nozzle,and obtains a geometric model of V-shape nozzle with a good performance; simulates the complex flow in supersonic ejector with FLUENT software and conducts contrastive analysis on the performance of various nozzles in numerical calculation.The result of numerical calculation shows that V-shape nozzle has certain influence on the distribution of flow field and impact wave at the supersonic nozzle and can effectively improve the performance of eiector and make the ejector reach a higher compression ratio and pressure recovery.%为了提高超音速引射器的性能,基于原有收敛形喷嘴的实验结果,重新设计了新型的V形喷嘴.通过改变V形喷嘴的波瓣数,使其引入更多涡流来提高引流流量,得到性能较好的V形喷嘴几何模型.采用FLUENT软件模拟超声速引射器中的复杂流动,对比分析了数值计算的各种喷嘴的性能.数值模拟结果显示:V形喷嘴对超音速喷嘴处的流场分布以及激波分布有一定的影响,可以有效提高引射器的性能,使引射器达到更大的压缩比和压力恢复.

  2. A survey of drag and heat reduction in supersonic flows by a counterflowing jet and its combinations

    Institute of Scientific and Technical Information of China (English)

    Wei HUANG

    2015-01-01

    题目:逆向喷流及其组合体在超声速气流中减阻防热功效研究进展  概总结归纳国内外逆向喷流及其组合体在超声速气流中减阻防热功效的研究进展,并给出逆向喷流在某些应用领域的建议,特别是喷流的不稳定性保护、减阻与热防护之间的权衡以及流动模态转换的工作参数和结构参数临界点选取等。%Drag reduction and thermal protection is very important for hypersonic vehicles, and a counterflowing jet and its combinations is one of the most promising drag and heat release reduction strategies. In the current survey, research progress on the drag and heat release reduction induced by a counterflowing jet and its combinations is summarized. Three combinatorial configurations are considered, namely the combination of the counterflowing jet and a forward-facing cavity, the combination of the counterflowing jet and an aerospike, and the combination of the counterflowing jet and energy deposition. In conclusion, some recommendations are provided, especially for jet instability protection, for the tradeoff between drag and heat release re-ductions, and for the critical points for the operational and geometric parameters in the flow mode transition.

  3. Investigation of turbines for driving supersonic compressors II : performance of first configuration with 2.2 percent reduction in nozzle flow area / Warner L. Stewart, Harold J. Schum, Robert Y. Wong

    Science.gov (United States)

    Stewart, Warner L; Schum, Harold J; Wong, Robert Y

    1952-01-01

    The experimental performance of a modified turbine for driving a supersonic compressor is presented and compared with the performance of the original configuration to illustrate the effect of small changes in the ratio of nozzle-throat area to rotor-throat area. Performance is based on the performance of turbines designed to operate with both blade rows close to choking. On the basis of the results of this investigation, the ratio of areas is concluded to become especially critical in the design of turbines such as those designed to drive high-speed, high-specific weight-flow compressors where the turbine nozzles and rotor are both very close to choking.

  4. Control of Flow Structure and Ignition of Hydrocarbon Fuel in Cavity and Behind Wallstep of Supersonic Duct by Filamentary DC Discharge

    Science.gov (United States)

    2011-01-01

    joint team of MSU, CIAM and IGP [25]. The efforts are arrowed on a comparative test of different plasma sources by the criteria of ignition...and IGP [23-24]. Fig.3.1.3. Schlieren images overlapped with the OH PLIF images: (a) Without and (b) with the pulsed discharge. Supersonic

  5. Direct Connect Supersonic Combustion Facility (Research Cell 22)

    Data.gov (United States)

    Federal Laboratory Consortium — Description: RC22 is a continuous-flow, direct-connect supersonic-combustion research facility that is capable of simulating flight conditions from Mach 3.0 to Mach...

  6. Magnetic geometry and particle source drive of supersonic divertor regimes

    Science.gov (United States)

    Bufferand, H.; Ciraolo, G.; Dif-Pradalier, G.; Ghendrih, P.; Tamain, Ph; Marandet, Y.; Serre, E.

    2014-12-01

    We present a comprehensive picture of the mechanisms driving the transition from subsonic to supersonic flows in tokamak plasmas. We demonstrate that supersonic parallel flows into the divertor volume are ubiquitous at low density and governed by the divertor magnetic geometry. As the density is increased, subsonic divertor plasmas are recovered. On detachment, we show the change in particle source can also drive the transition to a supersonic regime. The comprehensive theoretical analysis is completed by simulations in ITER geometry. Such results are essential in assessing the divertor performance and when interpreting measurements and experimental evidence.

  7. Existence of shocklets in a two-dimensional supersonic mixing layer and its influence on the flow structure

    Institute of Scientific and Technical Information of China (English)

    CAO; Wei

    2001-01-01

    .0, MNRAS,1992, 256: 349.[25]Hazard, C. , Morton, D. C., Terlevich, R. et al. , Nine new quasi-stellar objects with borad absorption lines, Astrophys.J. , 1984, 282: 33.[26]Osmer, P. S. , Q0353-383: The best case yet for abundance anomalies in quasars, Astrophys. J. , 1980, 237, 666.[27]Hamann, F. , Zuo, L., Tytler, D. , Broad Ne VIII λ774 emission from quasars in the HST-Fos snapshot survey (ABSNAP),Astrophys. J., 1995, 444: L69.[28]Laor, A. , Bahcall, J. N., Jannuzi, B. T. , The ultraviolet emission properties of five low-redshift active galactic unclei at high signal-to-noise ratio and spectral resolution, Astrophys. J., 1994, 420: 110.[29]Barthel, P. D., Tytler, D. R., Thomson, B., Optical spectra of distant radio loud quasars, A&AS, 1990, 82: 339.[30]Schmidt, M., Schneider, D. P., Gunn, J. E., Pc0910 + 5625: An optically selected quasar with a redshift of 4.04, Astro-phys. J., 1987, 321: L7.[31]Adams, M. T., Coleman, G. D., Stockman, H. S. et al., The spectrum of Markarian 132, Astrophys. J., 1978, 228:758.[32]Hammann, F. , Shields, J. C. , Ferland, G. J. et al. , Broad NE VIII lambda 744 emission from the Quasar PG 148 + 549,Astrophys. J., 1995, 454: 688.[33]Baldwin, J. A., McMahon, R., Hazard, C. et al., QSOs with narrow emission lines, Astrophys. J., 1988, 327: 103.[34]Baldwin, J. A. , Burbidge, E. M. , Hazard, C. et al. , A spectroscopic surrvey of 92 QSO candidates, Astrophys. J. ,1973, 185: 739.[35]Baldwin, J. A. , Ferland, G. J. , Korista, K. T., Very high density clumps and out flowing winds in QSO broad-line re-gions, Astrophys. J., 1996, 461: 664.[36]Ferland, G. J., Baldwin, J. A., Korista, K. T., High metal enrichments in luminous quasars, Astrophys. J., 461: 683.[37]Bceker, R. H., Helfand, D. J., White, R. L., The discovery of an X-ray selected radio-loud quasar at z = 3.9 AJ, 1992,104: 531.[38]Schneider, D. P., Lawrence, C. R., Schmide, M. et al., Deep optical and radio observations of the

  8. Supersonic Flutter of Laminated Curved Panels

    Directory of Open Access Journals (Sweden)

    M. Ganapathi

    1995-04-01

    Full Text Available Supersonic flutter analysis of laminated composite curved panels is investigated using doubly-curved, quadrilateral, shear flexible, shell element based on field-consistency approach. The formulation includes transverse shear deformation, in-plane and rotary inertias. The aerodynamic force is evaluated using two-dimensional static aerodynamic approximation for high supersonic flow. Initially, the model developed here is verified for the flutter analysis of flat plates. Numerical results are presented for isotropic, orthotropic and laminated anisotropic curved panels. A detailed parametric study is carried out to observe the effects of aspect and thickness ratios, number of layers, lamination scheme, and boundary conditions on flutter boundary.

  9. Supersonic gas shell for puff pinch experiments

    Science.gov (United States)

    Smith, R. S., III; Doggett, W. O.; Roth, I.; Stallings, C.

    1982-09-01

    An easy-to-fabricate, conical, annular supersonic nozzle has been developed for use in high-power, puff gas z-pinch experiments. A fast responding conical pressure probe has also been developed as an accurate supersonic gas flow diagnostic for evaluating the transient gas jet formed by the nozzle. Density profile measurements show that the magnitude and radial position of the gas annulus are fairly constant with distance from the nozzle, but the gas density in the center of the annulus increases with distance from the nozzle.

  10. Energy transfer upon collision of selectively excited CO{sub 2} molecules: State-to-state cross sections and probabilities for modeling of atmospheres and gaseous flows

    Energy Technology Data Exchange (ETDEWEB)

    Lombardi, A., E-mail: ebiu2005@gmail.com; Faginas-Lago, N.; Pacifici, L.; Grossi, G. [Dipartimento di Chimica, Università di Perugia, via Elce di Sotto 8, 06123 Perugia (Italy)

    2015-07-21

    Carbon dioxide molecules can store and release tens of kcal/mol upon collisions, and such an energy transfer strongly influences the energy disposal and the chemical processes in gases under the extreme conditions typical of plasmas and hypersonic flows. Moreover, the energy transfer involving CO{sub 2} characterizes the global dynamics of the Earth-atmosphere system and the energy balance of other planetary atmospheres. Contemporary developments in kinetic modeling of gaseous mixtures are connected to progress in the description of the energy transfer, and, in particular, the attempts to include non-equilibrium effects require to consider state-specific energy exchanges. A systematic study of the state-to-state vibrational energy transfer in CO{sub 2} + CO{sub 2} collisions is the focus of the present work, aided by a theoretical and computational tool based on quasiclassical trajectory simulations and an accurate full-dimension model of the intermolecular interactions. In this model, the accuracy of the description of the intermolecular forces (that determine the probability of energy transfer in molecular collisions) is enhanced by explicit account of the specific effects of the distortion of the CO{sub 2} structure due to vibrations. Results show that these effects are important for the energy transfer probabilities. Moreover, the role of rotational and vibrational degrees of freedom is found to be dominant in the energy exchange, while the average contribution of translations, under the temperature and energy conditions considered, is negligible. Remarkable is the fact that the intramolecular energy transfer only involves stretching and bending, unless one of the colliding molecules has an initial symmetric stretching quantum number greater than a threshold value estimated to be equal to 7.

  11. Energy transfer upon collision of selectively excited CO2 molecules: State-to-state cross sections and probabilities for modeling of atmospheres and gaseous flows.

    Science.gov (United States)

    Lombardi, A; Faginas-Lago, N; Pacifici, L; Grossi, G

    2015-07-21

    Carbon dioxide molecules can store and release tens of kcal/mol upon collisions, and such an energy transfer strongly influences the energy disposal and the chemical processes in gases under the extreme conditions typical of plasmas and hypersonic flows. Moreover, the energy transfer involving CO2 characterizes the global dynamics of the Earth-atmosphere system and the energy balance of other planetary atmospheres. Contemporary developments in kinetic modeling of gaseous mixtures are connected to progress in the description of the energy transfer, and, in particular, the attempts to include non-equilibrium effects require to consider state-specific energy exchanges. A systematic study of the state-to-state vibrational energy transfer in CO2 + CO2 collisions is the focus of the present work, aided by a theoretical and computational tool based on quasiclassical trajectory simulations and an accurate full-dimension model of the intermolecular interactions. In this model, the accuracy of the description of the intermolecular forces (that determine the probability of energy transfer in molecular collisions) is enhanced by explicit account of the specific effects of the distortion of the CO2 structure due to vibrations. Results show that these effects are important for the energy transfer probabilities. Moreover, the role of rotational and vibrational degrees of freedom is found to be dominant in the energy exchange, while the average contribution of translations, under the temperature and energy conditions considered, is negligible. Remarkable is the fact that the intramolecular energy transfer only involves stretching and bending, unless one of the colliding molecules has an initial symmetric stretching quantum number greater than a threshold value estimated to be equal to 7.

  12. Numerical and experimental investigations on supersonic ejectors

    Energy Technology Data Exchange (ETDEWEB)

    Bartosiewicz, Y.; Aidoun, Z. [CETC-Varennes, Natural Resources Canada (Canada); Desevaux, P. [CREST-UMR 6000, Belfort (France); Mercadier, Y. [Sherbrooke Univ. (Canada). THERMAUS

    2005-02-01

    Supersonic ejectors are widely used in a range of applications such as aerospace, propulsion and refrigeration. The primary interest of this study is to set up a reliable hydrodynamics model of a supersonic ejector, which may be extended to refrigeration applications. The first part of this work evaluated the performance of six well-known turbulence models for the study of supersonic ejectors. The validation concentrated on the shock location, shock strength and the average pressure recovery prediction. Axial pressure measurements with a capillary probe performed previously [Int. J. Turbo Jet Engines 19 (2002) 71; Conference Proc., 10th Int. Symp. Flow Visualization, Kyoto, Japan, 2002], were compared with numerical simulations while laser tomography pictures were used to evaluate the non-mixing length. The capillary probe has been included in the numerical model and the non-mixing length has been numerically evaluated by including an additional transport equation for a passive scalar, which acted as an ideal colorant in the flow. At this point, the results show that the k-omega-sst model agrees best with experiments. In the second part, the tested model was used to reproduce the different operation modes of a supersonic ejector, ranging from on-design point to off-design. In this respect, CFD turned out to be an efficient diagnosis tool of ejector analysis (mixing, flow separation), for design, and performance optimization (optimum entrainment and recompression ratios). (Author)

  13. Digital integrated control of a Mach 2.5 mixed-compression supersonic inlet and an augmented mixed-flow turbofan engine

    Science.gov (United States)

    Batterton, P. G.; Arpasi, D. J.; Baumbick, R. J.

    1974-01-01

    A digitally implemented integrated inlet-engine control system was designed and tested on a mixed-compression, axisymmetric, Mach 2.5, supersonic inlet with 45 percent internal supersonic area contraction and a TF30-P-3 augmented turbofan engine. The control matched engine airflow to available inlet airflow. By monitoring inlet terminal shock position and over-board bypass door command, the control adjusted engine speed so that in steady state, the shock would be at the desired location and the overboard bypass doors would be closed. During engine-induced transients, such as augmentor light-off and cutoff, the inlet operating point was momentarily changed to a more supercritical point to minimize unstarts. The digital control also provided automatic inlet restart. A variable inlet throat bleed control, based on throat Mach number, provided additional inlet stability margin.

  14. Design and Operation of a Supersonic Flow Cavity for a Non-Self-Sustained Electric Discharge Pumped Oxygen-Iodine Laser

    Science.gov (United States)

    2007-02-16

    static pressure taps are shown along the bottom cavity wall. OMA V camera. The emission signal was collected using a Thor Labs 1 m long fibre optic bundle...in the supersonic cavity wall), and the opposite end of the fibre optic bundle was placed in front of the spectrometer slit. The use of the fibre ... optic link greatly improved the alignment of the optical diagnostics system. The O2(a 1) concentration in the discharge afterglow and the SDO yield were

  15. 内送粉超声速等离子喷涂流场特性分析%Numerical Analysis of Plasma Flow with Supersonic Plasma Gun

    Institute of Scientific and Technical Information of China (English)

    谭超; 魏正英; 魏培; 李本强; 韩志海

    2015-01-01

    应用流体控制方程、传热传质方程、粒子输运方程、Maxwell电磁场方程建立多场耦合数学模型,通过数值计算方法研究超声速等离子喷枪内外等离子体流动特性。所采用的内送粉三维模型包含阴、阳电极固体以及阳极边界层区域,考虑了等离子气体的电离与复合反应,以及局域热平衡效应,得到了超声速等离子喷涂在纯氩和氩氢混合气氛中的气流温度场、速度场分布以及电弧电压分布。结果表明:在加入氢之后,喷枪内等离子体温度提高了30%,速度提高了67%;喷枪外气流速度和温度在距喷嘴出口0~50mm间梯度变化大于喷涂距离50~100mm,且径向速度和温度梯度变化随着喷涂距离增大越来越小。计算得到的电弧电压与测量值相差4.4%,说明了考虑阳极边界层后计算模型的合理性。%A multi-physic fields coupling mathematical model was established using fluid controlling equa⁃tions,heat and mass transfer equations,species transport equations and Maxwell's electromagnetic equations, to predict flow field characteristics inside and outside supersonic plasma gun. The three-dimensional model con⁃tained cathode,anode and anode boundary layers,and took ionization and recombination reactions,as well as non-local thermal equilibrium into consideration. The contours of temperature and velocity of plasma jet were dis⁃played under argon and argon-hydrogen working conditions, and arc voltage was also described. The results show that gas temperature inside plasma gun increases by 30%, and velocity increases by 67%after hydrogen was added to working gas. Besides,gas temperature and velocity decrease more sharply at distance of 0~50mm from nozzle exit than that of 50~100mm,while the decrease rate of the velocity and temperature are reduced with increasing axial distance. The relative error of calculated arc voltage is 4.4%,compared with measured value,il⁃lustrating the

  16. THERMAL AND AERODYNAMIC PERFORMANCES OF THE SUPERSONIC MOTION

    Directory of Open Access Journals (Sweden)

    Dejan P Ninković

    2010-01-01

    Full Text Available Generally speaking, Mach number of 4 can be taken as a boundary value for transition from conditions for supersonic, into the area of hypersonic flow, distinguishing two areas: area of supersonic in which the effects of the aerodynamic heating can be neglected and the area of hypersonic, in which the thermal effects become dominant. This paper presents the effects in static and dynamic areas, as well as presentation of G.R.O.M. software for determination of the values of aerodynamic derivatives, which was developed on the basis of linearized theory of supersonic flow. Validation of developed software was carried out through different types of testing, proving its usefulness for engineering practice in the area of supersonic wing aerodynamic loading calculations, even at high Mach numbers, with dominant thermal effects.

  17. Performance of Axial-Flow Supersonic Compressor of XJ55-FF-1 Turbojet Engine. II - Performance of Inlet Guide Vanes as Separate Component

    Science.gov (United States)

    Graham, Robert C.; Tysl, Edward R.

    1949-01-01

    The inlet wide vanes for the supersonic compressor of the XJ55-FF-1 engine were studied as a separate component in order to determine the performance prior to installation in the compressor test rig. Turning angles approached design values, and increased approximately to through the inlet Mach number range from 0.30 to choke. A sharp break in turning angle was experienced when the choke condition was reached. The total-pressure loss through the guide vanes was approximately 1 percent for the unchoked conditions and from 5 to 6 percent when choked.

  18. Experimental investigation of acoustic self-oscillation influence on decay process for underexpanded supersonic jet in submerged space

    Science.gov (United States)

    Aleksandrov, V. Yu.; Arefyev, K. Yu.; Ilchenko, M. A.

    2016-07-01

    Intensification of mixing between the gaseous working body ejected through a jet nozzle with ambient medium is an important scientific and technical problem. Effective mixing can increase the total efficiency of power and propulsion apparatuses. The promising approach, although poorly studied, is generation of acoustic self-oscillation inside the jet nozzle: this impact might enhance the decay of a supersonic jet and improve the mixing parameters. The paper presents peculiar properties of acoustic self-excitation in jet nozzle. The paper presents results of experimental study performed for a model injector with a set of plates placed into the flow channel, enabling the excitation of acoustic self-oscillations. The study reveals the regularity of under-expanded supersonic jet decay in submerged space for different flow modes. Experimental data support the efficiency of using the jet nozzle with acoustic self-oscillation in application to the systems of gas fuel supply. Experimental results can be used for designing new power apparatuses for aviation and space industry and for process plants.

  19. Space Shuttle Program (SSP) Orbiter Main Propulsion System (MPS) Gaseous Hydrogen (GH2) Flow Control Valve (FCV) Poppet Eddy Current (EC) Inspection Probability of Detection (POD) Study. Volume 2; Appendices

    Science.gov (United States)

    Piascik, Robert S.; Prosser, William H.

    2011-01-01

    The Director of the NASA Engineering and Safety Center (NESC), requested an independent assessment of the anomalous gaseous hydrogen (GH2) flow incident on the Space Shuttle Program (SSP) Orbiter Vehicle (OV)-105 during the Space Transportation System (STS)-126 mission. The main propulsion system (MPS) engine #2 GH2 flow control valve (FCV) LV-57 transition from low towards high flow position without being commanded. Post-flight examination revealed that the FCV LV-57 poppet had experienced a fatigue failure that liberated a section of the poppet flange. The NESC assessment provided a peer review of the computational fluid dynamics (CFD), stress analysis, and impact testing. A probability of detection (POD) study was requested by the SSP Orbiter Project for the eddy current (EC) nondestructive evaluation (NDE) techniques that were developed to inspect the flight FCV poppets. This report contains the Appendices to the main report.

  20. Space Shuttle Program (SSP) Orbiter Main Propulsion System (MPS) Gaseous Hydrogen (GH2) Flow Control Valve (FCV) Poppet Eddy Current (EC) Inspection Probability of Detection (POD) Study. Volume 1

    Science.gov (United States)

    Piascik, Robert S.; Prosser, William H.

    2011-01-01

    The Director of the NASA Engineering and Safety Center (NESC), requested an independent assessment of the anomalous gaseous hydrogen (GH2) flow incident on the Space Shuttle Program (SSP) Orbiter Vehicle (OV)-105 during the Space Transportation System (STS)-126 mission. The main propulsion system (MPS) engine #2 GH2 flow control valve (FCV) LV-57 transition from low towards high flow position without being commanded. Post-flight examination revealed that the FCV LV-57 poppet had experienced a fatigue failure that liberated a section of the poppet flange. The NESC assessment provided a peer review of the computational fluid dynamics (CFD), stress analysis, and impact testing. A probability of detection (POD) study was requested by the SSP Orbiter Project for the eddy current (EC) nondestructive evaluation (NDE) techniques that were developed to inspect the flight FCV poppets. This report contains the findings and recommendations from the NESC assessment.

  1. Investigation on the pressure matching performance of the constant area supersonic-supersonic ejector

    Directory of Open Access Journals (Sweden)

    Chen Jian

    2015-01-01

    Full Text Available The pressure matching performance of the constant area supersonic-supersonic ejector has been studied by varying the primary and secondary Mach numbers. The effect of the primary fluid injection configurations in ejector, namely peripheral and central, has been investigated as well. Schlieren pictures of flow structure in the former part of the mixing duct with different stagnation pressure ratio of the primary and secondary flows have been taken. Pressure ratios of the primary and secondary flows at the limiting condition have been obtained from the results of pressure and optical measurements. Additionally, a computational fluid dynamics analysis has been performed to clarify the physical meaning of the pressure matching performance diagram of the ejector. The obtained results show that the pressure matching performance of the constant area supersonic-supersonic ejector increases with the increase of the secondary Mach number, and the performance decreases slightly with the increase of the primary Mach number. The phenomenon of boundary layer separation induced by shock wave results in weaker pressure matching performance of the central ejector than that of the peripheral one. Furthermore, based on the observations of the experiment, a simplified analytical model has been proposed to predict the limiting pressure ratio, and the predicted values obtained by this model agree well with the experimental data.

  2. Nitrile/Buna N Material Failure Assessment for an O-Ring used on the Gaseous Hydrogen Flow Control Valve (FCV) of the Space Shuttle Main Engine

    Science.gov (United States)

    Wingard, Doug

    2006-01-01

    After the rollout of Space Shuttle Discovery in April 2005 in preparation for return-to-flight, there was a failure of the Orbiter (OV-103) helium signature leak test in the gaseous hydrogen (GH2) system. Leakage was attributed to the Flow Control Valve (FCV) in Main Engine 3. The FCV determined to be the source of the leak for OV-103 is designated as LV-58. The nitrile/Buna N rubber O-ring seal was removed from LV-58, and failure analysis indicated radial cracks providing leak paths in one quadrant. Cracks were eventually found in 6 of 9 FCV O-rings among the three Shuttle Orbiters, though none were as severe as those for LV-58, OV-103. Testing by EM10 at MSFC on all 9 FCV O- rings included: laser dimensional, Shore A hardness and properties from a dynamic mechanical analyzer (DMA) and an Instron tensile machine. The following test data was obtained on the cracked quadrant of the LV-58, OV-103 O-ring: (1) the estimated compression set was only 9.5%, compared to none for the rest of the O-ring; (2) Shore A hardness for the O.D. was higher by almost 4 durometer points than for the rest of the O-ring; and (3) DMA data showed that the storage/elastic modulus E was almost 25% lower than for the rest of the O-ring. Of the 8 FCV O-rings tested on an Instron, 4 yielded tensile strengths that were below the MIL spec requirement of 1350 psi-a likely influence of rubber cracking. Comparisons were made between values of modulus determined by DNA (elastic) and Instron (Young s). Each nitrile/Buna N O-ring used in the FCV conforms to the MIL-P-25732C specification. A number of such O-rings taken from shelf storage at MSFC and Kennedy Space Center (KSC) were used to generate a reference curve of DMA glass transition temperature (Tg) vs. shelf storage time ranging from 8 to 26 years. A similar reference curve of TGA onset temperature (of rubber weight loss) vs. shelf storage time was also generated. The DMA and TGA data for the used FCV O-rings were compared to the reference

  3. A Numerical Comparison of Symmetric and Asymmetric Supersonic Wind Tunnels

    Science.gov (United States)

    Clark, Kylen D.

    Supersonic wind tunnels are a vital aspect to the aerospace industry. Both the design and testing processes of different aerospace components often include and depend upon utilization of supersonic test facilities. Engine inlets, wing shapes, and body aerodynamics, to name a few, are aspects of aircraft that are frequently subjected to supersonic conditions in use, and thus often require supersonic wind tunnel testing. There is a need for reliable and repeatable supersonic test facilities in order to help create these vital components. The option of building and using asymmetric supersonic converging-diverging nozzles may be appealing due in part to lower construction costs. There is a need, however, to investigate the differences, if any, in the flow characteristics and performance of asymmetric type supersonic wind tunnels in comparison to symmetric due to the fact that asymmetric configurations of CD nozzle are not as common. A computational fluid dynamics (CFD) study has been conducted on an existing University of Michigan (UM) asymmetric supersonic wind tunnel geometry in order to study the effects of asymmetry on supersonic wind tunnel performance. Simulations were made on both the existing asymmetrical tunnel geometry and two axisymmetric reflections (of differing aspect ratio) of that original tunnel geometry. The Reynolds Averaged Navier Stokes equations are solved via NASAs OVERFLOW code to model flow through these configurations. In this way, information has been gleaned on the effects of asymmetry on supersonic wind tunnel performance. Shock boundary layer interactions are paid particular attention since the test section integrity is greatly dependent upon these interactions. Boundary layer and overall flow characteristics are studied. The RANS study presented in this document shows that the UM asymmetric wind tunnel/nozzle configuration is not as well suited to producing uniform test section flow as that of a symmetric configuration, specifically one

  4. Entropy Minimization Design Approach of Supersonic Internal Passages

    Directory of Open Access Journals (Sweden)

    Jorge Sousa

    2015-08-01

    Full Text Available Fluid machinery operating in the supersonic regime unveil avenues towards more compact technology. However, internal supersonic flows are associated with high aerodynamic and thermal penalties, which usually prevent their practical implementation. Indeed, both shock losses and the limited operational range represent particular challenges to aerodynamic designers that should be taken into account at the initial phase of the design process. This paper presents a design methodology for supersonic passages based on direct evaluations of the velocity field using the method of characteristics and computation of entropy generation across shock waves. This meshless function evaluation tool is then coupled to an optimization scheme, based on evolutionary algorithms that minimize the entropy generation across the supersonic passage. Finally, we assessed the results with 3D Reynolds Averaged Navier Stokes calculations.

  5. 超声速化学反应流场迎风格式数值模拟及并行计算%PARALLELIZED UPWIND FLUX SPLITTING SCHEME FOR SUPERSONIC REACTING FLOWS ON UNSTRUCTURED HYBRID MESHES

    Institute of Scientific and Technical Information of China (English)

    王江峰; 伍贻兆

    2007-01-01

    A parallelized upwind flux splitting scheme for supersonic reacting flows on hybrid meshes is presented. The complexity of super/hyper-sonic combustion flows makes it necessary to establish solvers with higher resolution and efficiency for multi-component Euler/N-S equations. Hence, a spatial second-order van Leer type flux vector splitting scheme is established by introducing auxiliary points in interpolation, and a domain decomposition method used on unstructured hybrid meshes for obtaining high calculating efficiency. The numerical scheme with five-stage Runge-Kutta time step method is implemented to the simulation of combustion flows, including the supersonic hydrogen/air combustion and the normal injection of hydrogen into reacting flows. Satisfying results are obtained compared with limited references.%基于有限体积迎风格式对超声速燃烧流场进行了的数值模拟.由于超声速燃烧流场绕流的复杂性,要求对多组分Euler/N-S方程求解的数值模拟方法应具有较高的计算精度及效率.本文引用辅助点方法建立了具有空间二阶精度的van Leer迎风矢通量分裂格式,并应用于超声速燃烧流场绕流的数值模拟.化学反应为氢气/空气十反应模型,采用考虑了化学反应特征时间的当地时间步长显式Runge-Kutta时间推进格式.对钝头体模型爆轰现象、后向台阶氢气喷射及二维内外流超声速燃烧流场模型进行了区域分裂技术的并行计算.计算结果与参考文献作了对比,得到了满意的结果.

  6. Experimental investigation of the structure of supersonic two-dimensional air microjets

    Science.gov (United States)

    Timofeev, Ivan; Aniskin, Vladimir; Mironov, Sergey

    2016-10-01

    We have experimentally studied the structure of supersonic underexpanded room-temperature air jets escaping from micronozzles with characteristic heights from 47 to 175 µm and widths within 2410-3900 µm in a range of Reynolds numbers of 1280-9460. The dimensions of the first shock cell are established. The supersonic core length of supersonic underexpanded air jets has been determined for the first time. A flow regime with a large supersonic core length has observed for air jets escaping from a 47µm high nozzle.

  7. An experimental study of the structure of supersonic flat underexpanded microjets

    Science.gov (United States)

    Aniskin, V. M.; Maslov, A. A.; Mironov, S. G.; Tsyryulnikov, I. S.; Timofeev, I. V.

    2015-05-01

    We have experimentally studied the structure of supersonic flat underexpanded room-temperature air jets escaping from micro nozzles with characteristic heights from 47 to 175 μm and widths within 2410-3900 μm in a range of Reynolds numbers of 1280-9460. The dimensions of the first shock cell are established. The supersonic core length of supersonic flat underexpanded air jets has been determined for the first time. A flow regime with a large supersonic core length has been observed for air jets escaping from a 47-μm-high nozzle.

  8. Experimental Evaluation of a Subscale Gaseous Hydrogen/gaseous Oxygen Coaxial Rocket Injector

    Science.gov (United States)

    Smith, Timothy D.; Klem, Mark D.; Breisacher, Kevin J.; Farhangi, Shahram; Sutton, Robert

    2002-01-01

    The next generation reusable launch vehicle may utilize a Full-Flow Stage Combustion (FFSC) rocket engine cycle. One of the key technologies required is the development of an injector that uses gaseous oxygen and gaseous hydrogen as propellants. Gas-gas propellant injection provides an engine with increased stability margin over a range of throttle set points. This paper summarizes an injector design and testing effort that evaluated a coaxial rocket injector for use with gaseous oxygen and gaseous hydrogen propellants. A total of 19 hot-fire tests were conducted up to a chamber pressure of 1030 psia, over a range of 3.3 to 6.7 for injector element mixture ratio. Post-test condition of the hardware was also used to assess injector face cooling. Results show that high combustion performance levels could be achieved with gas-gas propellants and there were no problems with excessive face heating for the conditions tested.

  9. The role of finite-difference methods in design and analysis for supersonic cruise

    Science.gov (United States)

    Townsend, J. C.

    1976-01-01

    Finite-difference methods for analysis of steady, inviscid supersonic flows are described, and their present state of development is assessed with particular attention to their applicability to vehicles designed for efficient cruise flight. Current work is described which will allow greater geometric latitude, improve treatment of embedded shock waves, and relax the requirement that the axial velocity must be supersonic.

  10. Flow field analysis and improvement on the large diameter butterfly valve in the supersonic wind tunnel%超音速风洞大口径蝶阀流场分析及改进

    Institute of Scientific and Technical Information of China (English)

    张耀平; 马东平; 丁天伟; 杨洋

    2011-01-01

    The configuration of the large diameter butterfly valve in the supersonic wind tunnel is introduced.Flow fields of the butterfly valve with different structure discs and different valve opening are analyzed by COSMOSFloWorks.The flow field is improved by adding cover for disc and punching on the cover.The worst service condition is avoided by adding bypass valves to butterfly valves,and so the failure rate is reduced and the life is prolonged.%介绍了超音速风洞大口径蝶阀的配置形式。运用COSMOSFloWorks软件分析了不同结构蝶板及蝶阀不同开度情况下的流场情况。通过在蝶板上增加蒙皮以及在蒙皮上开孔的方式改善了蝶阀的流场,蝶阀配置旁路阀的方式改善了蝶阀的使用工况,从而降低了蝶阀的故障率,延长了蝶阀的使用寿命。

  11. Effect of nanoparticle (Pd, Pd/Pt, Ni deposition on high temperature hydrogenation of Ti-V alloys in gaseous flow containing CO

    Directory of Open Access Journals (Sweden)

    S. Suwarno

    2017-02-01

    Full Text Available The hydrogenation properties of Ti-V hydrides coated with nanoparticles have been studied in gaseous mixtures of argon and hydrogen with and without additions of 1% CO. Nanoparticles of Pd, Ni, and co-deposited Pd/Pt with particle sizes of ~30–60 nm were formed by electroless deposition on the hydride surfaces. The alloy resistance to CO could be significantly improved by particle deposition. Large amounts of hydrogen were absorbed in a CO-containing gas when Ni and Pd/Pt deposition had been applied, while pure Pd deposition had no positive effect. Ni was found to have a stronger effect than those of Pd/Pt and Pd, possibly because of the size effect of Ni nanoparticles.

  12. Continuous supersonic plasma wind tunnel

    DEFF Research Database (Denmark)

    Andersen, S.A.; Jensen, Vagn Orla; Nielsen, P.

    1969-01-01

    The normal magnetic field configuration of a Q device has been modified to obtain a 'magnetic Laval nozzle'. Continuous supersonic plasma 'winds' are obtained with Mach numbers ~3. The magnetic nozzle appears well suited for the study of the interaction of supersonic plasma 'winds' with either...

  13. Growth of graphene films from non-gaseous carbon sources

    Science.gov (United States)

    Tour, James; Sun, Zhengzong; Yan, Zheng; Ruan, Gedeng; Peng, Zhiwei

    2015-08-04

    In various embodiments, the present disclosure provides methods of forming graphene films by: (1) depositing a non-gaseous carbon source onto a catalyst surface; (2) exposing the non-gaseous carbon source to at least one gas with a flow rate; and (3) initiating the conversion of the non-gaseous carbon source to the graphene film, where the thickness of the graphene film is controllable by the gas flow rate. Additional embodiments of the present disclosure pertain to graphene films made in accordance with the methods of the present disclosure.

  14. The Edge supersonic transport

    Science.gov (United States)

    Agosta, Roxana; Bilbija, Dushan; Deutsch, Marc; Gallant, David; Rose, Don; Shreve, Gene; Smario, David; Suffredini, Brian

    1992-01-01

    As intercontinental business and tourism volumes continue their rapid expansion, the need to reduce travel times becomes increasingly acute. The Edge Supersonic Transport Aircraft is designed to meet this demand by the year 2015. With a maximum range of 5750 nm, a payload of 294 passengers and a cruising speed of M = 2.4, The Edge will cut current international flight durations in half, while maintaining competitive first class, business class, and economy class comfort levels. Moreover, this transport will render a minimal impact upon the environment, and will meet all Federal Aviation Administration Part 36, Stage III noise requirements. The cornerstone of The Edge's superior flight performance is its aerodynamically efficient, dual-configuration design incorporating variable-geometry wingtips. This arrangement combines the benefits of a high aspect ratio wing at takeoff and low cruising speeds with the high performance of an arrow-wing in supersonic cruise. And while the structural weight concerns relating to swinging wingtips are substantial, The Edge looks to ever-advancing material technologies to further increase its viability. Heeding well the lessons of the past, The Edge design holds economic feasibility as its primary focus. Therefore, in addition to its inherently superior aerodynamic performance, The Edge uses a lightweight, largely windowless configuration, relying on a synthetic vision system for outside viewing by both pilot and passengers. Additionally, a fly-by-light flight control system is incorporated to address aircraft supersonic cruise instability. The Edge will be produced at an estimated volume of 400 aircraft and will be offered to airlines in 2015 at $167 million per transport (1992 dollars).

  15. Performance of a Code Migration for the Simulation of Supersonic Ejector Flow to SMP, MIC, and GPU Using OpenMP, OpenMP+LEO, and OpenACC Directives

    Directory of Open Access Journals (Sweden)

    C. Couder-Castañeda

    2015-01-01

    Full Text Available A serial source code for simulating a supersonic ejector flow is accelerated using parallelization based on OpenMP and OpenACC directives. The purpose is to reduce the development costs and to simplify the maintenance of the application due to the complexity of the FORTRAN source code. This research follows well-proven strategies in order to obtain the best performance in both OpenMP and OpenACC. OpenMP has become the programming standard for scientific multicore software and OpenACC is one true alternative for graphics accelerators without the need of programming low level kernels. The strategies using OpenMP are oriented towards reducing the creation of parallel regions, tasks creation to handle boundary conditions, and a nested control of the loop time for the programming in offload mode specifically for the Xeon Phi. In OpenACC, the strategy focuses on maintaining the data regions among the executions of the kernels. Experiments for performance and validation are conducted here on a 12-core Xeon CPU, Xeon Phi 5110p, and Tesla C2070, obtaining the best performance from the latter. The Tesla C2070 presented an acceleration factor of 9.86X, 1.6X, and 4.5X compared against the serial version on CPU, 12-core Xeon CPU, and Xeon Phi, respectively.

  16. Numerical Simulation of Jet Behavior and Impingement Characteristics of Preheating Shrouded Supersonic Jets

    Institute of Scientific and Technical Information of China (English)

    Guang-sheng WEI; Rong ZHU; Ting CHENG; Fei ZHAO

    2016-01-01

    As a novel supersonic j et technology,preheating shrouded supersonic j et was developed to deliver oxygen into molten bath efficiently and affordably.However,there has been limited research on the jet behavior and im-pingement characteristics of preheating shrouded supersonic j ets.Computational fluid dynamics (CFD)models were established to investigate the effects of main and shrouding gas temperatures on the characteristics of flow field and impingement of shrouded supersonic j et.The preheating shrouded supersonic j et behavior was simulated and meas-ured by numerical simulation and j et measurement experiment respectively.The influence of preheating shrouded su-personic j et on gas j et penetration and fluid flow in liquid bath was calculated by the CFD model which was validated against water model experiments.The results show that the uptrend of the potential core length of shrouded super-sonic j et would be accelerated with increasing the main and shrouding gas temperatures.Also,preheating supersonic j ets demonstrated significant advantages in penetrating and stirring the liquid bath.

  17. Analysis of liquid and gaseous oxygen influence on the combustion flow field of air heater%液氧与气氧对空气加热器燃烧流场的影响分析

    Institute of Scientific and Technical Information of China (English)

    冯军红; 沈赤兵; 赵芳

    2012-01-01

    The evaluation index, such as spray combustion, gas mixing and nozzle non-uniformity of air heater based on the combustor of liquid rocket engine, was studied with numerical simulation. The difference between the injectors with ethanol/liquid oxygen/air and the injectors with ethanol/gaseous oxygen/air in the combustion flow field was discussed and analyzed. Two cases were designed by changing the characteristic length of combustor, and the performance of air heaters were investigated by numerical simulation. The results show that, the flame structure is affected obviously by the phase of oxygen. The length of flame with liquid oxygen is larger than that of gaseous oxygen. More hot gas fills in the recirculation zone in the forepart of combustor with gaseous oxygen case, which increases the gas temperature near the faceplate, and worsens the thermal environment on the faceplate. The high quality flow field on the nozzle exit is obtained with the designed air heater. The characteristic length of air heater with gaseous oxygen is at least a quarter less than that of air heater with liquid oxygen to keep the good uniformity of nozzle exit.%针对一种基于液体火箭发动机燃烧室结构的空气加热器,采用数值仿真技术研究了加热器内部喷雾燃烧、燃气掺混以及出口流场分布等参数.分析对比了采用酒精/液氧/空气与酒精/气氧/空气两种不同氧化剂物态三组元同轴直流式喷嘴所得到的燃烧流场的区别,并通过改变燃烧室特征长度,分析了两种计算工况的加热器的性能差异.结果表明,喷入氧化剂的物态对燃烧流场影响较大,采用液氧喷嘴的火焰较长,气氧喷嘴的火焰分布较宽,且相对于液氧喷嘴,气氧喷嘴的燃烧室前端回流区由于掺混较多的燃气,导致喷注面板附近燃气温度较高,面板承热压力较大.设计的加热器均可保证两种喷嘴的出口流场品质较高,在保证流场出口品质的原则上,气氧喷

  18. Sub-scale Direct Connect Supersonic Combustion Facility (Research Cell 18)

    Data.gov (United States)

    Federal Laboratory Consortium — Description: RC18 is a continuous-flow, direct-connect, supersonic-combustion research facility that is capable of simulating flight conditions from Mach 3.0 to Mach...

  19. Design project: LONGBOW supersonic interceptor

    Science.gov (United States)

    Stoney, Robert; Baker, Matt; Capstaff, Joseph G.; Dishman, Robert; Fick, Gregory; Frick, Stephen N.; Kelly, Mark

    1993-01-01

    A recent white paper entitled 'From the Sea' has spotlighted the need for Naval Aviation to provide overland support to joint operations. The base for this support, the Aircraft Carrier (CVN), will frequently be unable to operate within close range of the battleground because of littoral land-based air and subsurface threats. A high speed, long range, carrier capable aircraft would allow the CVN to provide timely support to distant battleground operations. Such an aircraft, operating as a Deck-Launched Interceptor (DLI), would also be an excellent counter to Next Generation Russian Naval Aviation (NGRNA) threats consisting of supersonic bombers, such as the Backfire, equipped with the next generation of high-speed, long-range missiles. Additionally, it would serve as an excellent high speed Reconnaissance airplane, capable of providing Battle Force commanders with timely, accurate pre-mission targeting information and post-mission Bomb Damage Assessment (BDA). Recent advances in computational hypersonic airflow modeling has produced a method of defining aircraft shapes that fit a conical shock flow model to maximize the efficiency of the vehicle. This 'Waverider' concept provides one means of achieving long ranges at high speeds. A Request for Proposal (RFP) was issued by Professor Conrad Newberry that contained design requirements for an aircraft to accomplish the above stated missions, utilizing Waverider technology.

  20. Influence of Gaseous Media Flow in the Dual Ar-H2-H2O/air Atmosphere Setup on the Scale Growth Kinetics of Crofer 22APU Ferritic Stainless Steel

    Science.gov (United States)

    Stygar, Mirosław; Dąbrowa, Juliusz; Dziembaj, Piotr; Brylewski, Tomasz

    2017-02-01

    The problem of gaseous media distribution within the metallic interconnects in solid oxide fuel cells (SOFCs) and its influence on the oxidation resistance of the applied materials is currently of great interest. In the presented work, an influence of gas flow within the dual Ar-H2-H2O/air atmosphere experimental setup on the oxidation behavior of the Crofer 22APU ferritic stainless steel was investigated. Examination of the sample oxidized for 1000 h in temperature of 800 °C revealed the presence of coaxial regions on the scale surface, with the differences in scale's thicknesses in those regions being clearly visible. Additionally, the morphology of the surface changed significantly in a function of the radial distance from the sample's center. To further examine the phenomena of uneven gas distribution, a model of the dual-atmosphere setup was created, using Ansys Workbench software. Obtained results suggest that the correlation between scale morphology and distribution of temperature and pressure on the sample's surface, created by gas flow in the system, can be justified.

  1. Study of the shock structure of supersonic, dual, coaxial, jets

    Energy Technology Data Exchange (ETDEWEB)

    Lee, K. H.; Lee, J. H.; Kim, H. D. [Andong National Univ., Andong (Korea, Republic of)

    2001-07-01

    The shock structure of supersonic, dual, coaxial jet is experimentally investigated. Eight different kinds of coaxial, dual nozzles are employed to observe the major features of the near field shock structure of the supersonic, coaxial, dual jets. Four convergent-divergent supersonic nozzles having the Mach number of 2.0 and 3.0, and are used to compare the coaxial jet flows discharging from two sonic nozzles. The primary pressure ratio is changed in the range between 4.0 and 10.0 and the assistant jet pressure ratio from 1.0 to 4.0. The results obtained show that the impinging angle, nozzle geometry and pressure ratio significantly affect the near field shock structure, Mach disk location and Mach disk diameter. The annular shock system is found depending the assistant and primary jet pressure ratios.

  2. Influence of solar flares and CME on the gaseous envelopes of hot Jupiter exoplanets

    Science.gov (United States)

    Bisikalo, Dmitry; Cherenkov, Alexander

    2015-08-01

    Hot Jupiters, i.e. exoplanets having masses comparable to the mass of Jupiter and semimajor axes shorter than 0.1~AU, have a number of outstanding features, caused mostly by their proximity to the host star. As a matter of fact, the atmospheres of several dozens of these planets fill their Roche lobes, which results in a powerful outflow of material from the planet toward the host star. In addition, since the planet orbits at a short distance, its orbital velocity is supersonic, which causes the formation of a bow shock ahead of the planet. These effects substantially change the mechanism of interaction between the planet's gaseous envelope (atmosphere) and the stellar wind. In this paper, we investigate the flow pattern in the vicinity of a typical hot Jupiter by using 3D gas dynamic simulations. By considering the star-planet interaction we study variations in the structure of the hot Jupiter's envelope and estimate the variations of atmosphere’s mass-loss rate caused by the influence of typical solar flares and coronal mass ejections.

  3. Supersonic Jet Interactions in a Plenum Chamber

    Directory of Open Access Journals (Sweden)

    K. M. Venugopal

    2004-07-01

    Full Text Available Understanding thè supersonic jet interactions in a plenum chamber is essential for thè design of hot launch systems. Static tests were conducted in a small-scale rocket motor ioaded with a typical nitramine propellaiit to produce a nozzle exit Mach number of 3. This supersonic jet is made to interact with plenum chambers having both open and closed sides. The distance between thè nozzle exit and thè back piate of plenum chamber are varied from 2. 5 to 7. 0 times thè nozzle exit diameter. The pressure rise in thè plenum chamber was measured using pressure transducers mounted at different locatìons. The pressure-time data were analysed to obtain an insight into thè flow field in thè plenum chamber. The maximum pressure exerted on thè back piate of plenum chamber is about 25-35 per cent. of thè maximum stagnation pressure developed in thè rocket motor. Ten static tests were carried out to obtain thè effect of axial distance between thè nozzle exit and thè plenum chamber back piate, and stagnation pressure in thè rocket motoron thè flow field in thè open-sided and closed-sided plenum chambers configurations.

  4. Tesseract supersonic business transport

    Science.gov (United States)

    Reshotko, Eli; Garbinski, Gary; Fellenstein, James; Botting, Mary; Hooper, Joan; Ryan, Michael; Struk, Peter; Taggart, Ben; Taillon, Maggie; Warzynski, Gary

    1992-01-01

    This year, the senior level Aerospace Design class at Case Western Reserve University developed a conceptual design of a supersonic business transport. Due to the growing trade between Asia and the United States, a transpacific range was chosen for the aircraft. A Mach number of 2.2 was chosen, too, because it provides reasonable block times and allows the use of a large range of materials without a need for active cooling. A payload of 2,500 lbs. was assumed corresponding to a complement of nine passengers and crew, plus some light cargo. With these general requirements set, the class was broken down into three groups. The aerodynamics of the aircraft were the responsibility of the first group. The second developed the propulsion system. The efforts of both the aerodynamics and propulsion groups were monitored and reviewed for weight considerations and structural feasibility by the third group. Integration of the design required considerable interaction between the groups in the final stages. The fuselage length of the final conceptual design was 107.0 ft, while the diameter of the fuselage was 7.6 ft. The delta wing design consisted of an aspect ratio of 1.9 with a wing span of 47.75 ft and mid-chord length of 61.0 ft. A SNECMA MCV 99 variable-cycle engine design was chosen for this aircraft.

  5. Tesseract: Supersonic business transport

    Science.gov (United States)

    Reshotko, Eli; Garbinski, Gary

    1992-01-01

    This year, the senior level Aerospace Design class at Case Western Reserve University developed a conceptual design of a supersonic business transport. Due to the growing trade between Asia and the United States, a transpacific range has been chosen for the aircraft. A Mach number of 2.2 was chosen too because it provides reasonable block times and allows the use of a large range of materials without a need for active cooling. A payload of 2500 lbs. has been assumed corresponding to a complement of nine (passengers and crew) plus some light cargo. With these general requirements set, the class was broken down into three groups. The aerodynamics of the aircraft were the responsibility of the first group. The second developed the propulsion system. The efforts of both the aerodynamics and propulsion groups were monitored and reviewed for weight considerations and structural feasibility by the third group. Integration of the design required considerable interaction between the groups in the final stages. The fuselage length of the final conceptual design was 107.0 ft. while the diameter of the fuselage was 7.6 ft. The delta wing design consisted of an aspect ratio of 1.9 with a wing span of 47.75 ft and midcord length of 61.0 ft. A SNEMCA MCV 99 variable-cycle engine design was chosen for this aircraft.

  6. Analysis of pressure perturbation sources on a generic space launcher after-body in supersonic flow using zonal turbulence modeling and dynamic mode decomposition

    Science.gov (United States)

    Statnikov, Vladimir; Sayadi, Taraneh; Meinke, Matthias; Schmid, Peter; Schröder, Wolfgang

    2015-01-01

    A sparsity promoting dynamic mode decomposition (DMD) combined with a classical data-based statistical analysis is applied to the turbulent wake of a generic axisymmetric configuration of an Ariane 5-like launcher at Ma∞ = 6.0 computed via a zonal Reynolds-averaged Navier-Stokes/large-eddy simulation (RANS/LES) method. The objective of this work is to gain a better understanding of the wake flow dynamics of the generic launcher by clarification and visualization of initially unknown pressure perturbation sources on its after-body in coherent flow patterns. The investigated wake topology is characterized by a subsonic cavity region around the cylindrical nozzle extension which is formed due to the displacement effect of the afterexpanding jet plume emanating from the rocket nozzle (Mae = 2.52, pe/p∞ = 100) and the shear layer shedding from the main body. The cavity region contains two toroidal counter-rotating large-scale vortices which extensively interact with the turbulent shear layer, jet plume, and rocket walls, leading to the shear layer instability process to be amplified. The induced velocity fluctuations in the wake and the ultimately resulting pressure perturbations on the after-body feature three global characteristic frequency ranges, depending on the streamwise position inside the cavity. The most dominant peaks are detected at SrD r3 = 0.85 ± 0.075 near the nozzle exit, while the lower frequency peaks, in the range of SrD r2 = 0.55 ± 0.05 and SrD r1 = 0.25 ± 0.05, are found to be dominant closer to the rocket's base. A sparse promoting DMD algorithm is applied to the time-resolved velocity field to clarify the origin of the detected peaks. This analysis extracts three low-frequency spatial modes at SrD = 0.27, 0.56, and 0.85. From the three-dimensional shape of the DMD modes and the reconstructed modulation of the mean flow in time, it is deduced that the detected most dominant peaks of SrD r3 ≈ 0.85 are caused by the radial flapping motion of

  7. Very low dose gamma irradiation stimulates gaseous exchange and carboxylation efficiency, but inhibits vascular sap flow in groundnut (Arachis hypogaea L.).

    Science.gov (United States)

    Ahuja, Sumedha; Singh, Bhupinder; Gupta, Vijay Kumar; Singhal, R K; Venu Babu, P

    2014-02-01

    An experiment was carried out to determine the effect of low dose gamma radiation on germination, plant growth, nitrogen and carbon fixation and carbon flow and release characteristics of groundnut. Dry seeds of groundnut variety Trombay groundnut 37A (TG 37A), a radio mutant type developed by Bhabha Atomic Research Centre (BARC), Mumbai, India, were subjected to the pre-sowing treatment of gamma radiation within low to high dose physiological range, i.e., 0.0, 0.0082, 0.0164. 0.0328, 0.0656, 0.1312, 5, 25, 100, 500 Gray (Gy) from a cobalt source ((60)Co). Observations were recorded for the radiation effect on percentage germination, vigour, gas exchange attributes such as photosynthetic rate, stomatal conductance and transpiration rate, chlorophyll content, root exudation in terms of (14)C release, vascular sap flow rate and activities of rate defining carbon and nitrogen assimilating enzymes such as ribulose-1,5-bisphosphate carboxylase (rubisco) and nitrate reductase (NR). Seed germination was increased by 10-25% at the lower doses up to 5 Gy while the improvement in plant vigour in the same dose range was much higher (22-84%) than the unirradiated control. For radiation exposure above 5 Gy, a dose-dependent decline in germination and plant vigour was measured. No significant effect was observed on the photosynthesis at radiation exposure below 5 Gy but above 5 Gy dose there was a decline in the photosynthetic rate. Stomatal conductance and transpiration rate, however, were only inhibited at a high dose of 500 Gy. Leaf rubisco activity and NR activities remained unaffected at all the investigated doses of gamma irradiation. Mean root exudation and sap flow rate of the irradiated plants, irrespective of the dose, was reduced over the unirradiated control more so in a dose-dependent manner. Results indicated that a very low dose of gamma radiation, in centigray to gray range, did not pose any threat and in fact stimulated metabolic functions in such a way to aid

  8. Tribology in Gaseous Hydrogen

    Science.gov (United States)

    Sawae, Yoshinori; Sugimura, Joich

    Hydrogen is expected as a clean and renewable energy carrier for future environment-friendly society. Many machine elements in hydrogen energy systems should be operating within hydrogen gas and tribological behavior, such as friction and wear, of bearings and seals are affected by the hydrogen environment through some interactions between material surfaces and gaseous hydrogen, i.e., physisorption of hydrogen molecules and following chemisorptions of dissociated atoms on metal surfaces, formation of metal hydride and reduction of metal oxide layer by hydrogen atoms diffused into bulk. Therefore, friction and wear characteristics of tribomaterials in the hydrogen environment should be appropriately understood to establish a design guideline for reliable hydrogen utilizing systems. This paper reviews the current knowledge about the effect of hydrogen on friction and wear of materials, and then describes our recent progress of hydrogen research in the tribology field.

  9. Gaseous fuel reactor systems for aerospace applications

    Science.gov (United States)

    Thom, K.; Schwenk, F. C.

    1977-01-01

    Research on the gaseous fuel nuclear rocket concept continues under the programs of the U.S. National Aeronautics and Space Administration (NASA) Office for Aeronautics and Space Technology and now includes work related to power applications in space and on earth. In a cavity reactor test series, initial experiments confirmed the low critical mass determined from reactor physics calculations. Recent work with flowing UF6 fuel indicates stable operation at increased power levels. Preliminary design and experimental verification of test hardware for high-temperature experiments have been accomplished. Research on energy extraction from fissioning gases has resulted in lasers energized by fission fragments. Combined experimental results and studies indicate that gaseous-fuel reactor systems have significant potential for providing nuclear fission power in space and on earth.

  10. Numerical Study for Hysteresis Phenomena of Shock Wave Reflection in Overexpanded Axisymmetric Supersonic Jet

    Institute of Scientific and Technical Information of China (English)

    Tsuyoshi Yasunobu; Ken Matsuoka; Hideo Kashimura; Shigeru Matsuo; Toshiaki Setoguchi

    2006-01-01

    When the high-pressure gas is exhausted to the vacuum chamber from the supersonic nozzle, the overexpanded supersonic jet is formed at specific condition. In two-dimensional supersonic jet, furthermore, it is known that the hysteresis phenomena for the reflection type of shock wave in the flow field is occurred under the quasi-steady flow and for instance, the transitional pressure ratio between the regular reflection (RR) and Mach reflection (MR) is affected by this phenomenon. Many papers have described the hysteresis phenomena for underexpanded supersonic jet, but this phenomenon under the overexpanded axisymmetric jet has not been detailed in the past papers. The purpose of this study is to clear the hysteresis phenomena for the reflection type of shock wave at the overexpanded axisymmetric jet using the TVD method and to discuss the characteristic of hysteresis phenomena.

  11. Self—Induced Oscillation of Supersonic Jet During Impingement on Cylindrical Body

    Institute of Scientific and Technical Information of China (English)

    HideoKashimura; ShenYu; 等

    1998-01-01

    The phenomena of the interaction between a supersonic jet and an obstacle are related to the problems of the aeronautical and other industrial engineerings.When a supersonic jet impinges on an obstacle,the self induced oscillation occurs under several conditions.The flow charactersitics caused by the impingement of underexpanded supersonic jet on an obstacle have been investigated.However,it seems that the mechanism of self induced oscillation and the factor which dominates if have not been detailed in the published papers,The characteristics of the self induced oscillation of the supersonic jet during the impingement on a cylindrical body are investigated using the visualization of flow fields and the numerical calculations in this study.

  12. Supersonic Dislocation Bursts in Silicon

    Science.gov (United States)

    Hahn, E. N.; Zhao, S.; Bringa, E. M.; Meyers, M. A.

    2016-06-01

    Dislocations are the primary agents of permanent deformation in crystalline solids. Since the theoretical prediction of supersonic dislocations over half a century ago, there is a dearth of experimental evidence supporting their existence. Here we use non-equilibrium molecular dynamics simulations of shocked silicon to reveal transient supersonic partial dislocation motion at approximately 15 km/s, faster than any previous in-silico observation. Homogeneous dislocation nucleation occurs near the shock front and supersonic dislocation motion lasts just fractions of picoseconds before the dislocations catch the shock front and decelerate back to the elastic wave speed. Applying a modified analytical equation for dislocation evolution we successfully predict a dislocation density of 1.5 × 1012 cm-2 within the shocked volume, in agreement with the present simulations and realistic in regards to prior and on-going recovery experiments in silicon.

  13. Properties of Supersonic Evershed Downflows

    Science.gov (United States)

    Pozuelo, S. Esteban; Bellot Rubio, L. R.; de la Cruz Rodríguez, J.

    2016-12-01

    We study supersonic Evershed downflows in a sunspot penumbra by means of high spatial resolution spectropolarimetric data acquired in the Fe i 617.3 nm line with the CRISP instrument at the Swedish 1 m Solar Telescope. Physical observables, such as Dopplergrams calculated from line bisectors and Stokes V zero-crossing wavelengths, and Stokes V maps in the far red-wing, are used to find regions where supersonic Evershed downflows may exist. We retrieve the line-of-sight velocity and the magnetic field vector in these regions using two-component inversions of the observed Stokes profiles with the help of the SIR code. We follow these regions during their lifetime to study their temporal behavior. Finally, we carry out a statistical analysis of the detected supersonic downflows to characterize their physical properties. Supersonic downflows are contained in compact patches moving outward, which are located in the mid- and outer penumbra. They are observed as bright, roundish structures at the outer end of penumbral filaments that resemble penumbral grains. The patches may undergo fragmentations and mergings during their lifetime; some of them are recurrent. Supersonic downflows are associated with strong and rather vertical magnetic fields with a reversed polarity compared to that of the sunspot. Our results suggest that downflows returning back to the solar surface with supersonic velocities are abruptly stopped in dense deep layers and produce a shock. Consequently, this shock enhances the temperature and is detected as a bright grain in the continuum filtergrams, which could explain the existence of outward-moving grains in the mid- and outer penumbra.

  14. Analysis of Gaseous Slip Flow and Heat Transfer in Micro Rectangular Channels%微矩形槽道内的气体滑移流动和传热分析

    Institute of Scientific and Technical Information of China (English)

    肖睿; 辛明道; 朱恂

    2001-01-01

    This article present the theoretical analysis of gas flow and heat transfer in micro rectangular channels in the regime of velocity-slip and temperature-jump. The model is built on the assumption that the bottom wall of the channel is in uniform heat flux while the other three walls are adiabatic, and that the flow and heat transfer is of the hydraulic and thermal fully developed laminar flow of the incompressible fluid. Analytic solutions of the cross-section distributions of both the velocity and temperature are obtained.The friction and heat transfer performances are discussed. The agreement between analytic solutions and experimental results existed shows that in a definite extension of Knudsen number the traditional Navier-Stoks equations and energy equations with the boundary conditions of slip velocity and temperature jump can describe the gaseous flow and heat transfer mechanisms in micro rectangular channels.%分析了微矩形槽道内的不可压缩气体在速度滑移和温度跳跃区的流动和传热过程。在分析模型中,假定矩形槽道底面定热流加热,其余三面绝热,流动和换热均为充分发展,且处于滑移流动区。给出了截面上速度分布和温度分布的分析解,讨论了阻力特性和换热特性,并与实验结果作了比较。二者的吻合程度表明,在一定的Knudsen数范围内,传统的Navier-Stokes方程和能量方程在考虑了速度滑移和温度跳跃影响后可以描述微矩形槽道内的气体流动和传热过程。

  15. Micro Ramps in Supersonic Turbulent Boundary Layers: An experimental and numerical study

    NARCIS (Netherlands)

    Sun, Z.

    2014-01-01

    The micro vortex generator (MVG) is used extensively in low speed aerodynamic problems and is now extended into the supersonic flow regime to solve undesired flow features that are associated with shock wave boundary layer interactions (SWBLI) such as flow separation and associated unsteadiness of t

  16. Parametric effect on the mixing of the combination of a hydrogen porthole with an air porthole in transverse gaseous injection flow fields

    Science.gov (United States)

    Li, Lang-quan; Huang, Wei; Yan, Li; Li, Shi-bin

    2017-10-01

    The dual transverse injection system with a front hydrogen porthole and a rear air porthole arranged in tandem is proposed, and this is a realistic approach for mixing enhancement and penetration improvement of transverse injection in a scramjet combustor. The influence of this dual transverse injection system on mixing characteristics has been evaluated numerically based on grid independency analysis and code validation. The numerical approach employed in the current study has been validated against the available experimental data in the open literature, and the predicted wall static pressure distributions show reasonable agreement with the experimental data for the cases with different jet-to-crossflow pressure ratios. The obtained results predicted by the three-dimensional Reynolds-average Navier - Stokes (RANS) equations coupled with the two equation k-ω shear stress transport (SST) turbulence model show that the air pothole has an great impact on penetration depth and mixing efficiency, and the effect of air jet on flow field varies with different values of the aspect ratio. The air porthole with larger aspect ratio can increase the fuel penetration depth. However, when the aspect ratio is relatively small, the fuel penetration depth decreases, and even smaller than that of the single injection system. At the same time, the air pothole has a highly remarkable improvement on mixing efficiency, especially in the near field. The smaller the aspect ratio of the air porthole is, the higher the mixing efficiency in the near field is. This is due to its larger circulation in the near field. The dual injection system owns more losses of stagnation pressure than the single injection system.

  17. Cool gaseous nebulae

    CERN Document Server

    Shaver, P A; Pottasch, S R

    1979-01-01

    The electron temperatures of diffuse gaseous nebulae have long been thought to be close to 10/sup 4/K. Much lower temperatures were derived from some of the early radio continuum and recombination line work, but these were generally considered to be wrong for a variety of reasons. While there is little doubt that the bright nebulae do indeed have temperatures of approximately 8000-9000K, there are strong indications that some nebulae of lower densities have much lower temperatures,

  18. Coherent structures in a supersonic complex nozzle

    Science.gov (United States)

    Magstadt, Andrew; Berry, Matthew; Glauser, Mark

    2016-11-01

    The jet flow from a complex supersonic nozzle is studied through experimental measurements. The nozzle's geometry is motivated by future engine designs for high-performance civilian and military aircraft. This rectangular jet has a single plane of symmetry, an additional shear layer (referred to as a wall jet), and an aft deck representative of airframe integration. The core flow operates at a Mach number of Mj , c = 1 . 6 , and the wall jet is choked (Mj , w = 1 . 0). This high Reynolds number jet flow is comprised of intense turbulence levels, an intricate shock structure, shear and boundary layers, and powerful corner vortices. In the present study, stereo PIV measurements are simultaneously sampled with high-speed pressure measurements, which are embedded in the aft deck, and far-field acoustics in the anechoic chamber at Syracuse University. Time-resolved schlieren measurements have indicated the existence of strong flow events at high frequencies, at a Strouhal number of St = 3 . 4 . These appear to result from von Kàrmàn vortex shedding within the nozzle and pervade the entire flow and acoustic domain. Proper orthogonal decomposition is applied on the current data to identify coherent structures in the jet and study the influence of this vortex street. AFOSR Turbulence and Transition Program (Grant No. FA9550-15-1-0435) with program managers Dr. I. Leyva and Dr. R. Ponnappan.

  19. Properties of Supersonic Evershed Downflows

    CERN Document Server

    Pozuelo, Sara Esteban; Rodriguez, Jaime de la Cruz

    2016-01-01

    We study supersonic Evershed downflows in a sunspot penumbra by means of high spatial resolution spectropolarimetric data acquired in the Fe I 617.3 nm line with the CRISP instrument at the Swedish 1-m Solar Telescope. Physical observables, such as Dopplergrams calculated from line bisectors and Stokes V zero-crossing wavelengths, and Stokes V maps in the far red wing, are used to find regions where supersonic Evershed downflows may exist. We retrieve the LOS velocity and the magnetic field vector in these regions using two-component inversions of the observed Stokes profiles with the help of the SIR code. We follow these regions during their lifetime to study their temporal behavior. Finally, we carry out a statistical analysis of the detected supersonic downflows to characterize their physical properties. Supersonic downflows are contained in compact patches moving outward, which are located in the mid and outer penumbra. They are observed as bright, roundish structures at the outer end of penumbral filamen...

  20. The effects of profiles on supersonic jet noise

    Science.gov (United States)

    Tiwari, S. N.; Bhat, T. R. S.

    1994-01-01

    The effect of velocity profiles on supersonic jet noise are studied by using stability calculations made for a shock-free coannular jet, with both the inner and outer flows supersonic. The Mach wave emission process is modeled as the noise generated by the large scale turbulent structures or the instability waves in the mixing region. Both the vortex-sheet and the realistic finite thickness shear layer models are considered. The stability calculations were performed for both inverted and normal velocity profiles. Comparisons are made with the results for an equivalent single jet, based on equal thrust, mass flow rate and exit area to that of the coannular jet. The advantages and disadvantages of these velocity profiles as far as noise radiation is concerned are discussed. It is shown that the Rayleigh's model prediction of the merits and demerits of different velocity profiles are in good agreement with the experimental data.

  1. Aeroelastic coupling in sonic boom optimization of a supersonic aircraft

    OpenAIRE

    Vázquez, Mariano; Dervieux, Alain; Koobus, Bruno

    2003-01-01

    In this paper, we consider a multi-disciplinary optimization problem where the initial shape of a wing is sought in order to cope, after elastic deformation by the flow, with some optimality conditions. We propose a medium-strong coupling which allows to consider different softwares communicating a small number of times. Applications to the optimization of the AGARD Wing 445.6 and a flexible supersonic aircraft wing are presented.

  2. Gas turbine engine with supersonic compressor

    Science.gov (United States)

    Roberts, II, William Byron; Lawlor, Shawn P.

    2015-10-20

    A gas turbine engine having a compressor section using blades on a rotor to deliver a gas at supersonic conditions to a stator. The stator includes one or more of aerodynamic ducts that have converging and diverging portions for deceleration of the gas to subsonic conditions and to deliver a high pressure gas to combustors. The aerodynamic ducts include structures for changing the effective contraction ratio to enable starting even when designed for high pressure ratios, and structures for boundary layer control. In an embodiment, aerodynamic ducts are provided having an aspect ratio of two to one (2:1) or more, when viewed in cross-section orthogonal to flow direction at an entrance to the aerodynamic duct.

  3. Linear stability analysis of supersonic axisymmetric jets

    Directory of Open Access Journals (Sweden)

    Zhenhua Wan

    2014-01-01

    Full Text Available Stabilities of supersonic jets are examined with different velocities, momentum thicknesses, and core temperatures. Amplification rates of instability waves at inlet are evaluated by linear stability theory (LST. It is found that increased velocity and core temperature would increase amplification rates substantially and such influence varies for different azimuthal wavenumbers. The most unstable modes in thin momentum thickness cases usually have higher frequencies and azimuthal wavenumbers. Mode switching is observed for low azimuthal wavenumbers, but it appears merely in high velocity cases. In addition, the results provided by linear parabolized stability equations show that the mean-flow divergence affects the spatial evolution of instability waves greatly. The most amplified instability waves globally are sometimes found to be different from that given by LST.

  4. Pressure distribution and aerodynamic coefficients associated with heat addition to supersonic air stream adjacent to two-dimensional supersonic wing

    Science.gov (United States)

    Pinkel, I Irving; Serafini, John S; Gregg, John L

    1952-01-01

    The modifications in the pressure distributions and the aerodynamic coefficients associated with additions of heat to the two-dimensional supersonic in viscid flow field adjacetnt to the lower surface of of a 5-percent-thickness symmetrical circular-arc wing are presented in this report. The pressure distributions are obtained by the use of graphical method which gives the two-dimensional supersonic inviscid flow field obtained with moderate heat addition. The variation is given of the lift-drag ratio and of the aerodynamic coefficients of lift, drag, and moment with free stream Mach number, angle of attack, and parameters defining extent and amount of heat addition. The six graphical solutions used in this study included Mach numbers of 3.0 and 5.0 and angles of attack of 0 degrees and 2 degrees.

  5. Supersonic Flow Control by Magnetic Field

    Science.gov (United States)

    2005-12-01

    of the potential equation on the computational mesh gives the system of algebraic equations for the potential magnitudes in the mesh nodes with...computational cell and making use of the integral formulae of vectorial analysis, one can write out finite-volume notation of plasma equation for a

  6. Large Eddy Simulation of Supersonic Inlet Flows

    Science.gov (United States)

    1998-04-01

    percentage error in the first derivative may be computed as a function of the resolution, using kh = 2%/N, and error= 100 \\k’h — kh\\/kh. Figure 2 compares...the C-D schemes to the standard Pade schemes. Note that all the schemes show 100 % error for the two-delta waves (two points per wave). This is...are needed at the boundary nodes to close the system. Consider j = 1. The following general expression may be written for f[ and f": aQf [ + axf2 + h

  7. Supersonic unstalled flutter. [aerodynamic loading of thin airfoils induced by cascade motion

    Science.gov (United States)

    Adamczyk, J. J.; Goldstein, M. E.; Hartmann, M. J.

    1978-01-01

    Flutter analyses were developed to predict the onset of supersonic unstalled flutter of a cascade of two-dimensional airfoils. The first of these analyzes the onset of supersonic flutter at low levels of aerodynamic loading (i.e., backpressure), while the second examines the occurrence of supersonic flutter at moderate levels of aerodynamic loading. Both of these analyses are based on the linearized unsteady inviscid equations of gas dynamics to model the flow field surrounding the cascade. These analyses are utilized in a parametric study to show the effects of cascade geometry, inlet Mach number, and backpressure on the onset of single and multi degree of freedom unstalled supersonic flutter. Several of the results are correlated against experimental qualitative observation to validate the models.

  8. Numerical simulation of carbon dioxide removal from natural gas using supersonic nozzles

    Science.gov (United States)

    Sun, Wenjuan; Cao, Xuewen; Yang, Wen; Jin, Xuetang

    2017-03-01

    Supersonic separation is a technology potentially applicable to natural gas decarbonation process. Preliminary research on the performance of supersonic nozzle in the removal of carbon dioxide from natural gas is presented in this study. Computational Fluid Dynamics (CFD) technique is used to simulate the flow behavior inside the supersonic nozzle. The CFD model is validated successfully by comparing its results to the data borrowed from the literature. The results indicate that the liquefaction of carbon dioxide can be achieved in the properly designed nozzle. Shock wave occurs in the divergent section of the nozzle with the increase of the back pressure, destroying the liquefaction process. In the supersonic separator, the shock wave should be kept outside of the nozzle.

  9. Turbulent diffusion of chemically reacting gaseous admixtures

    Science.gov (United States)

    Elperin, T.; Kleeorin, N.; Liberman, M.; Rogachevskii, I.

    2014-11-01

    We study turbulent diffusion of chemically reacting gaseous admixtures in a developed turbulence. In our previous study [Phys. Rev. Lett. 80, 69 (1998), 10.1103/PhysRevLett.80.69] using a path-integral approach for a delta-correlated in a time random velocity field, we demonstrated a strong modification of turbulent transport in fluid flows with chemical reactions or phase transitions. In the present study we use the spectral τ approximation that is valid for large Reynolds and Peclet numbers and show that turbulent diffusion of the reacting species can be strongly depleted by a large factor that is the ratio of turbulent and chemical times (turbulent Damköhler number). We have demonstrated that the derived theoretical dependence of a turbulent diffusion coefficient versus the turbulent Damköhler number is in good agreement with that obtained previously in the numerical modeling of a reactive front propagating in a turbulent flow and described by the Kolmogorov-Petrovskii-Piskunov-Fisher equation. We have found that turbulent cross-effects, e.g., turbulent mutual diffusion of gaseous admixtures and turbulent Dufour effect of the chemically reacting gaseous admixtures, are less sensitive to the values of stoichiometric coefficients. The mechanisms of the turbulent cross-effects differ from the molecular cross-effects known in irreversible thermodynamics. In a fully developed turbulence and at large Peclet numbers the turbulent cross-effects are much larger than the molecular ones. The obtained results are applicable also to heterogeneous phase transitions.

  10. Bulk Flows and End of the Dark Ages with the SKA

    CERN Document Server

    Maio, Umberto; Koopmans, Leon V E

    2015-01-01

    The early Universe is a precious probe of the birth of primordial objects, first star formation events and consequent production of photons and heavy elements. Higher-order corrections to the cosmological linear perturbation theory predicts the formation of coherent supersonic gaseous streaming motions at decoupling time. These bulk flows impact the gas cooling process and determine a cascade effect on the whole baryon evolution. By analytical estimates and N-body hydrodynamical chemistry numerical simulations including atomic and molecular evolution, gas cooling, star formation, feedback effects and metal spreading for individual species from different stellar populations according to the proper yields and lifetimes, we discuss the role of these primordial bulk flows at the end of the dark ages and their detectable impacts during the first Gyr in view of the upcoming SKA mission. Early bulk flows can inhibit molecular gas cooling capabilities, suppressing star formation, metal spreading and the abundance of ...

  11. Supersonic Chordwise Bending Flutter in Cascades

    Science.gov (United States)

    1975-05-31

    such a flutter boundary can be made by utilizing the trend lines predicted from a supersonic analysis based on supersonic cascade theory (Appendix I...bonding agent was injected via hypodermic needles after the blade tabs were properly inserted, The integrity and repeatability of the mounting of the indi...in conjunction with NASTRAN predictions and supersonic cascade aerodynamic computa- tions. Comparisons between theory and experiment are discussed. DD

  12. The fractal measurement of experimental images of supersonic turbulent mixing layer

    Institute of Scientific and Technical Information of China (English)

    ZHAO YuXin; YI ShiHe; TIAN LiFeng; HE Lin; CHENG ZhongYu

    2008-01-01

    Flow Visualization of supersonic mixing layer has been studied based on the high spatiotemporal resolution Nano-based Planar Laser Scattering (NPLS) method in SML-1 wind tunnel. The corresponding images distinctly reproduced the flow structure of laminar, transitional and turbulent region, with which the fractal meas-urement can be implemented. Two methods of measuring fractal dimension wereintroduced and compared. The fractal dimension of the transitional region and the fully developing turbulence region of supersonic mixing layer were measured based on the box-counting method. In the transitional region, the fractal dimension will increase with turbulent intensity. In the fully developing turbulent region, the fractal dimension will not vary apparently for different flow structures, which em-bodies the self-similarity of supersonic turbulence.

  13. The fractal measurement of experimental images of supersonic turbulent mixing layer

    Institute of Scientific and Technical Information of China (English)

    2008-01-01

    Flow visualization of supersonic mixing layer has been studied based on the high spatiotemporal resolution Nano-based Planar Laser Scattering(NPLS) method in SML-1 wind tunnel. The corresponding images distinctly reproduced the flow structure of laminar,transitional and turbulent region,with which the fractal measurement can be implemented. Two methods of measuring fractal dimension were introduced and compared. The fractal dimension of the transitional region and the fully developing turbulence region of supersonic mixing layer were measured based on the box-counting method. In the transitional region,the fractal dimension will increase with turbulent intensity. In the fully developing turbulent region,the fractal dimension will not vary apparently for different flow structures,which em-bodies the self-similarity of supersonic turbulence.

  14. Mixing of Supersonic Streams

    Science.gov (United States)

    Hawk, C. W.; Landrum, D. B.; Muller, S.; Turner, M.; Parkinson, D.

    1998-01-01

    The Strutjet approach to Rocket Based Combined Cycle (RBCC) propulsion depends upon fuel-rich flows from the rocket nozzles and turbine exhaust products mixing with the ingested air for successful operation in the ramjet and scramjet modes. It is desirable to delay this mixing process in the air-augmented mode of operation present during low speed flight. A model of the Strutjet device has been built and is undergoing test to investigate the mixing of the streams as a function of distance from the Strutjet exit plane during simulated low speed flight conditions. Cold flow testing of a 1/6 scale Strutjet model is underway and nearing completion. Planar Laser Induced Fluorescence (PLIF) diagnostic methods are being employed to observe the mixing of the turbine exhaust gas with the gases from both the primary rockets and the ingested air simulating low speed, air augmented operation of the RBCC. The ratio of the pressure in the turbine exhaust duct to that in the rocket nozzle wall at the point of their intersection is the independent variable in these experiments. Tests were accomplished at values of 1.0, 1.5 and 2.0 for this parameter. Qualitative results illustrate the development of the mixing zone from the exit plane of the model to a distance of about 10 rocket nozzle exit diameters downstream. These data show the mixing to be confined in the vertical plane for all cases, The lateral expansion is more pronounced at a pressure ratio of 1.0 and suggests that mixing with the ingested flow would be likely beginning at a distance of 7 nozzle exit diameters downstream of the nozzle exit plane.

  15. Study on the Characteristics of Supersonic Coanda Jet

    Institute of Scientific and Technical Information of China (English)

    ShigeruMatsuo; ShenYu; 等

    1998-01-01

    Techniques using coanda effect have been applied to the fluid control devices.In this field,experimental studies were so far performed for the spiral jet obtained by the Coanda jet issuing from a conical cylinder with an annular slit ,thrust vectoring of supersonic Coanda jets and so on,It is important from the viewpoints of effective applications to investigate the characteristics of the supersonic coanda jet in detail,In the present study,The effects of pressure rations and nozzle configurations on the characteristics of the supersonic COanda jet have been investigated.experimentally by a schlieren optical method and pressure measurements.Furthermore.Navier-Stokes equations were solved numerically using a 2nd-order TVD finite-volume scheme with a 3rd-order three stage Runge-Kutta method for time integration,κ-ε model was used in the computations.The effects of initial conditions on Coanda flow were investigated numerically.As a result,the simulated flow fields were compared with experimental data in good agreement qualitatively.

  16. Interaction of a swept shock wave and a supersonic wake

    Science.gov (United States)

    He, G.; Zhao, Y. X.; Zhou, J.

    2017-03-01

    The interaction of a swept shock wave and a supersonic wake has been studied. The swept shock wave is generated by a swept compression sidewall, and the supersonic wake is generated by a wake generator. The flow field is visualized with the nanoparticle-based planar laser scattering method, and a supplementary numerical simulation is conducted by solving the Reynolds-averaged Navier-Stokes equations. The results show that the pressure rise induced by the swept shock wave can propagate upstream in the wake, which makes the location where vortices are generated move upstream, thickens the laminar section of the wake, and enlarges the generated vortices. The wake is swept away from the swept compression sidewall by the pressure gradient of the swept shock wave. This pressure gradient is not aligned with the density gradient of the supersonic wake, so the baroclinic torque generates streamwise vorticity and changes the distribution of the spanwise vorticity. The wake shock is curved, so the flow downstream of it is non-uniform, leaving the swept shock wave being distorted. A three-dimensional Mach disk structure is generated when the wake shock interacts with the swept shock wave.

  17. Interaction of a swept shock wave and a supersonic wake

    Science.gov (United States)

    He, G.; Zhao, Y. X.; Zhou, J.

    2017-09-01

    The interaction of a swept shock wave and a supersonic wake has been studied. The swept shock wave is generated by a swept compression sidewall, and the supersonic wake is generated by a wake generator. The flow field is visualized with the nanoparticle-based planar laser scattering method, and a supplementary numerical simulation is conducted by solving the Reynolds-averaged Navier-Stokes equations. The results show that the pressure rise induced by the swept shock wave can propagate upstream in the wake, which makes the location where vortices are generated move upstream, thickens the laminar section of the wake, and enlarges the generated vortices. The wake is swept away from the swept compression sidewall by the pressure gradient of the swept shock wave. This pressure gradient is not aligned with the density gradient of the supersonic wake, so the baroclinic torque generates streamwise vorticity and changes the distribution of the spanwise vorticity. The wake shock is curved, so the flow downstream of it is non-uniform, leaving the swept shock wave being distorted. A three-dimensional Mach disk structure is generated when the wake shock interacts with the swept shock wave.

  18. Ethylene tetrafluoroethylene nanofibers prepared by CO2 laser supersonic drawing

    Directory of Open Access Journals (Sweden)

    A. Suzuki

    2013-06-01

    Full Text Available Ethylene tetrafluoroethylene (ETFE nanofibers were prepared by carbon dioxide (CO2 laser irradiation of asspun ETFE fibers with four different melt flow rates (MFRs in a supersonic jet that was generated by blowing air into a vacuum chamber through the fiber injection orifice. The drawability and superstructure of fibers produced by CO2 laser supersonic drawing depend on the laser power, the chamber pressure, the fiber injection speed, and the MFR. Nanofibers obtained using a laser power of 20 W, a chamber pressure of 20 kPa, and an MFR of 308 g•10 min–1 had an average diameter of 0.303 µm and a degree of crystallinity of 54%.

  19. Features of Ignition and Stable Combustion in Supersonic Combustor

    Science.gov (United States)

    Goldfeld, M.; Starov, A.; Timofeev, K.

    2009-01-01

    Present paper describes the results of experimental investigations of the supersonic combustor with entrance Mach numbers from 2 to 4 at static pressure from 0.8 to 2.5 bars, total temperature from 2000K to 3000K. Hydrogen and kerosene were used as fuel. The conditions, under which the self-ignition and intensive combustion of the fuel realized were found. Position of ignition area in the channel was determined and features of flame propagation in the channel presented. A possibility to ensure an efficient combustion of hydrogen and kerosene at a high supersonic flow velocity at the combustor entrance without special throttling and/or pseudo-shock introduction was shown. Analysis of applicability of existing methods of criterion descriptions of conditions of self-ignition and extinction of combustion is executed for generalization of experimental results on the basis of results obtained.

  20. Effect of Microjet Injection on Supersonic Jet Noise

    Science.gov (United States)

    Zaman, K. B. M. Q.; Podboy, G. G.

    2010-01-01

    The effect of microjet (jet) injection on the noise from supersonic jets is investigated. Three convergent-divergent (C-D) nozzles and one convergent nozzle, all having the same exit diameters, are used in the study. The jets are injected perpendicular to the primary jet close to the nozzle lip from six equally-spaced ports having a jet-to-primary-jet diameter ratio of 0.0054. Effects in the over-expanded, fully expanded as well as underexpanded flow regimes are explored. Relative to the effect on subsonic jets, larger reductions in the overall sound pressure level (OASPL) are achieved in most supersonic conditions. The largest reductions are typically associated with suppression of screech and transonic tones. For a shock-free, fully expanded case, the OASPL reductions achieved are comparable to that in the subsonic case; the same correlation, found for subsonic jet noise reduction at shallow observation angle, applies.

  1. An Interactive Method of Characteristics Java Applet to Design and Analyze Supersonic Aircraft Nozzles

    Science.gov (United States)

    Benson, Thomas J.

    2014-01-01

    The Method of Characteristics (MOC) is a classic technique for designing supersonic nozzles. An interactive computer program using MOC has been developed to allow engineers to design and analyze supersonic nozzle flow fields. The program calculates the internal flow for many classic designs, such as a supersonic wind tunnel nozzle, an ideal 2D or axisymmetric nozzle, or a variety of plug nozzles. The program also calculates the plume flow produced by the nozzle and the external flow leading to the nozzle exit. The program can be used to assess the interactions between the internal, external and plume flows. By proper design and operation of the nozzle, it may be possible to lessen the strength of the sonic boom produced at the rear of supersonic aircraft. The program can also calculate non-ideal nozzles, such as simple cone flows, to determine flow divergence and nonuniformities at the exit, and its effect on the plume shape. The computer program is written in Java and is provided as free-ware from the NASA Glenn central software server.

  2. Accuracy Of Hot-Wire Anemometry In Supersonic Turbulence

    Science.gov (United States)

    Logan, Pamela; Mckenzie, Robert L.; Bershader, Daniel

    1989-01-01

    Sensitivity of hot-wire probe compared to laser-induced-florescence measurements. Report discusses factors affecting readings of hot-wire anemometer in turbulent supersonic boundary layer. Presents theoretical analysis of responses of hot-wire probe to changes in flow; also compares measurements by hot-wire probe with measurements of same flows by laser-induced fluorescence (LIF). Because LIF provides spatially and temporally resolved data on temperature, density, and pressure, provides independent means to determine responses of hot-wire anemometers to these quantities.

  3. Charge Transfer Properties Through Graphene for Applications in Gaseous Detectors

    CERN Document Server

    Franchino, S.; Hall-Wilton, R.; Jackman, R.B.; Muller, H.; Nguyen, T.T.; de Oliveira, R.; Oliveri, E.; Pfeiffer, D.; Resnati, F.; Ropelewski, L.; Smith, J.; van Stenis, M.; Streli, C.; Thuiner, P.; Veenhof, R.

    2016-07-11

    Graphene is a single layer of carbon atoms arranged in a honeycomb lattice with remarkable mechanical and electrical properties. Regarded as the thinnest and narrowest conductive mesh, it has drastically different transmission behaviours when bombarded with electrons and ions in vacuum. This property, if confirmed in gas, may be a definitive solution for the ion back-flow problem in gaseous detectors. In order to ascertain this aspect, graphene layers of dimensions of about 2x2cm$^2$, grown on a copper substrate, are transferred onto a flat metal surface with holes, so that the graphene layer is freely suspended. The graphene and the support are installed into a gaseous detector equipped with a triple Gaseous Electron Multiplier (GEM), and the transparency properties to electrons and ions are studied in gas as a function of the electric fields. The techniques to produce the graphene samples are described, and we report on preliminary tests of graphene-coated GEMs.

  4. Charge transfer properties through graphene for applications in gaseous detectors

    Energy Technology Data Exchange (ETDEWEB)

    Franchino, S.; Gonzalez-Diaz, D. [CERN, European Organization for Nuclear Research, CH-1211, Geneva 23 (Switzerland); Hall-Wilton, R. [ESS, European Spallation Source, Tunavägen 24, 223 63 Lund (Sweden); Jackman, R.B. [London Centre for Nanotechnology and the Department of Electronic and Electrical Engineering, University College London, 17-19 Gordon Street, WC1H 0AH (United Kingdom); Muller, H. [CERN, European Organization for Nuclear Research, CH-1211, Geneva 23 (Switzerland); Nguyen, T.T. [London Centre for Nanotechnology and the Department of Electronic and Electrical Engineering, University College London, 17-19 Gordon Street, WC1H 0AH (United Kingdom); Oliveira, R. de; Oliveri, E. [CERN, European Organization for Nuclear Research, CH-1211, Geneva 23 (Switzerland); Pfeiffer, D. [CERN, European Organization for Nuclear Research, CH-1211, Geneva 23 (Switzerland); ESS, European Spallation Source, Tunavägen 24, 223 63 Lund (Sweden); Resnati, F., E-mail: filippo.resnati@cern.ch [CERN, European Organization for Nuclear Research, CH-1211, Geneva 23 (Switzerland); ESS, European Spallation Source, Tunavägen 24, 223 63 Lund (Sweden); Ropelewski, L. [CERN, European Organization for Nuclear Research, CH-1211, Geneva 23 (Switzerland); Smith, J. [London Centre for Nanotechnology and the Department of Electronic and Electrical Engineering, University College London, 17-19 Gordon Street, WC1H 0AH (United Kingdom); Stenis, M. van [CERN, European Organization for Nuclear Research, CH-1211, Geneva 23 (Switzerland); Streli, C. [Atominstitut, Technische Universität Wien, Stadionallee 2, 1020 Vienna (Austria); Thuiner, P. [CERN, European Organization for Nuclear Research, CH-1211, Geneva 23 (Switzerland); Atominstitut, Technische Universität Wien, Stadionallee 2, 1020 Vienna (Austria); and others

    2016-07-11

    Graphene is a single layer of carbon atoms arranged in a honeycomb lattice with remarkable mechanical and electrical properties. Regarded as the thinnest and narrowest conductive mesh, it has drastically different transmission behaviours when bombarded with electrons and ions in vacuum. This property, if confirmed in gas, may be a definitive solution for the ion back-flow problem in gaseous detectors. In order to ascertain this aspect, graphene layers of dimensions of about 2×2 cm{sup 2}, grown on a copper substrate, are transferred onto a flat metal surface with holes, so that the graphene layer is freely suspended. The graphene and the support are installed into a gaseous detector equipped with a triple Gaseous Electron Multiplier (GEM), and the transparency properties to electrons and ions are studied in gas as a function of the electric fields. The techniques to produce the graphene samples are described, and we report on preliminary tests of graphene-coated GEMs.

  5. Characteristics of response factors of coaxial gaseous rocket injectors

    Science.gov (United States)

    Janardan, B. A.; Daniel, B. R.; Zinn, B. T.

    1975-01-01

    The results of an experimental investigation undertaken to determine the frequency dependence of the response factors of various gaseous propellant rocket injectors subject to axial instabilities are presented. The injector response factors were determined, using the modified impedance-tube technique, under cold-flow conditions simulating those observed in unstable rocket motors. The tested injectors included a gaseous-fuel injector element, a gaseous-oxidizer injector element and a coaxial injector with both fuel and oxidizer elements. Emphasis was given to the determination of the dependence of the injector response factor upon the open-area ratio of the injector, the length of the injector orifice, and the pressure drop across the injector orifices. The measured data are shown to be in reasonable agreement with the corresponding injector response factor data predicted by the Feiler and Heidmann model.

  6. Implicit LES for Supersonic Microramp Vortex Generator: New Discoveries and New Mechanisms

    OpenAIRE

    Qin Li; Chaoqun Liu

    2011-01-01

    This paper serves as a summary of our recent work on LES for supersonic MVG. An implicitly implemented large eddy simulation (ILES) by using the fifth-order WENO scheme is applied to study the flow around the microramp vortex generator (MVG) at Mach 2.5 and Re⁡θ=1440. A number of new discoveries on the flow around supersonic MVG have been made including spiral points, surface separation topology, source of the momentum deficit, inflection surface, Kelvin-Helmholtz instability, vortex ring ge...

  7. Unsteady transonic aerodynamics and aeroelastic calculations at low-supersonic freestreams

    Science.gov (United States)

    Guruswamy, Guru P.; Goorjian, Peter M.

    1988-01-01

    A computational procedure is presented to simulate transonic unsteady flows and corresponding aeroelasticity of wings at low-supersonic freestreams. The flow is modeled by using the transonic small-perturbation theory. The structural equations of motions are modeled using modal equations of motion directly coupled with aerodynamics. Supersonic freestreams are simulated by properly accounting for the boundary conditions based on pressure waves along the flow characteristics in streamwise planes. The flow equations are solved using the time-accurate, alternating-direction implicit finite-difference scheme. The coupled aeroelastic equations of motion are solved by an integration procedure based on the time-accurate, linear-acceleration method. The flow modeling is verified by comparing calculations with experiments for both steady and unsteady flows at supersonic freestreams. The unsteady computations are made for oscillating wings. Comparisons of computed results with experiments show good agreement. Aeroelastic responses are computed for a rectangular wing at Mach numbers ranging from subtransonic to upper-transonic (supersonic) freestreams. The extension of the transonic dip into the upper transonic regime is illustrated.

  8. Observation of supersonic turbulent wakes by laser Fourier densitometry (LFD)

    Science.gov (United States)

    Gresillon, D.; Cabrit, B.; Bonnet, J. P.; Gemaux, G.

    Laser Fourier Densitometry (LFD) is an optical method appropriate for turbulent flow observations. It uses the collective scattering of coherent light, by optical index inhomogeneities. The principle of this method is described. It provides a signal proportional to the space Fourier transform amplitude of index distribution for a wavevector k defined by the optical arrangement. For a fluctuating flow, this amplitude is a function of time, and its frequency spectrum can be observed. The spectrum shape provides elementary parameters of the flow, such as: direction, modulus of mean velocity, and local temperature. It also provides means to distinguish different kinds of density fluctuations, such as convected inhomogeneities, or acoustic waves. The respective level of these different fluctuations types can be measured, as well as their power scale-law and absolute level. A compact optical bench has been set on a nozzle flow. The results of measurements performed in two supersonic wake configurations are presented, for Mach numbers of 1.6 and 4.2. These include density fluctuation spectra in supersonic flows, acoustic waves, variations with position, and comparison with hot wire anemometry.

  9. Innovative Monitoring of Atmospheric Gaseous Hydrogen Fluoride

    Directory of Open Access Journals (Sweden)

    Stefano Dugheri

    2016-01-01

    Full Text Available Hydrogen fluoride (HF is a basic raw material for a wide variety of industrial products, with a worldwide production capacity of more than three million metric tonnes. A novel method for determining particulate fluoride and gaseous hydrogen fluoride in air is presented herewith. Air was sampled using miniaturised 13 mm Swinnex two-stage filter holders in a medium-flow pumping system and through the absorption of particulate fluoride and HF vapours on cellulose ester filters uncoated or impregnated with sodium carbonate. Furthermore, filter desorption from the holders and the extraction of the pentafluorobenzyl ester derivative based on solid-phase microextraction were performed using an innovative robotic system installed on an xyz autosampler on-line with gas chromatography (GC/mass spectrometry (MS. After generating atmospheres of a known concentration of gaseous HF, we evaluated the agreement between the results of our sampling method and those of the conventional preassembled 37 mm cassette (±8.10%; correlation coefficient: 0.90. In addition, precision (relative standard deviation for n=10, 4.3%, sensitivity (0.2 μg/filter, and linearity (2.0–4000 μg/filter; correlation coefficient: 0.9913 were also evaluated. This procedure combines the efficiency of GC/MS systems with the high throughput (96 samples/day and the quantitative accuracy of pentafluorobenzyl bromide on-sample derivatisation.

  10. Innovative Monitoring of Atmospheric Gaseous Hydrogen Fluoride

    Science.gov (United States)

    Bonari, Alessandro; Pompilio, Ilenia; Monti, Alessandro; Arcangeli, Giulio

    2016-01-01

    Hydrogen fluoride (HF) is a basic raw material for a wide variety of industrial products, with a worldwide production capacity of more than three million metric tonnes. A novel method for determining particulate fluoride and gaseous hydrogen fluoride in air is presented herewith. Air was sampled using miniaturised 13 mm Swinnex two-stage filter holders in a medium-flow pumping system and through the absorption of particulate fluoride and HF vapours on cellulose ester filters uncoated or impregnated with sodium carbonate. Furthermore, filter desorption from the holders and the extraction of the pentafluorobenzyl ester derivative based on solid-phase microextraction were performed using an innovative robotic system installed on an xyz autosampler on-line with gas chromatography (GC)/mass spectrometry (MS). After generating atmospheres of a known concentration of gaseous HF, we evaluated the agreement between the results of our sampling method and those of the conventional preassembled 37 mm cassette (±8.10%; correlation coefficient: 0.90). In addition, precision (relative standard deviation for n = 10, 4.3%), sensitivity (0.2 μg/filter), and linearity (2.0–4000 μg/filter; correlation coefficient: 0.9913) were also evaluated. This procedure combines the efficiency of GC/MS systems with the high throughput (96 samples/day) and the quantitative accuracy of pentafluorobenzyl bromide on-sample derivatisation. PMID:27829835

  11. Gaseous Galaxy Halos

    CERN Document Server

    Putman, M E; Joung, M R

    2012-01-01

    Galactic halo gas traces inflowing star formation fuel and feedback from a galaxy's disk and is therefore crucial to our understanding of galaxy evolution. In this review, we summarize the multi-wavelength observational properties and origin models of Galactic and low redshift spiral galaxy halo gas. Galactic halos contain multiphase gas flows that are dominated in mass by the ionized component and extend to large radii. The densest, coldest halo gas observed in neutral hydrogen (HI) is generally closest to the disk ( 10^5.5 K) and cold mode in simulations, with the compressed material close to the disk the coldest and densest, in agreement with observations. There is evidence in halo gas observations for radiative and mechanical feedback mechanisms, including escaping photons from the disk, supernova-driven winds, and a galactic fountain. Satellite accretion also leaves behind abundant halo gas. This satellite gas interacts with the existing halo medium, and much of this gas will become part of the diffuse h...

  12. Reverse Circulation Drilling Method Based on a Supersonic Nozzle for Dust Control

    Directory of Open Access Journals (Sweden)

    Dongyu Wu

    2016-12-01

    Full Text Available To reduce dust generated from drilling processes, a reverse circulation drilling method based on a supersonic nozzle is proposed. The suction performance is evaluated by the entrainment ratio. A series of preliminary laboratory experiments based on orthogonal experimental design were conducted to test the suction performance and reveal the main factors. Computational fluid dynamics (CFD were conducted to thoroughly understand the interaction mechanism of the flows. The Schlieren technique was further carried out to reveal the flow characteristic of the nozzle. The results show that the supersonic nozzle can significantly improve the reverse circulation effect. A high entrainment ratio up to 0.76 was achieved, which implied strong suction performance. The CFD results agreed well with experimental data with a maximum difference of 17%. This work presents the great potential for supersonic nozzles and reverse circulation in dust control, which is significant to protect the envrionment and people’s health.

  13. Research on the mechanics of underwater supersonic gas jets

    Science.gov (United States)

    Shi, Honghui; Wang, Boyi; Dai, Zhenqing

    2010-03-01

    An experimental research was carried out to study the fluid mechanics of underwater supersonic gas jets. High pressure air was injected into a water tank through converging-diverging nozzles (Laval nozzles). The jets were operated at different conditions of over-, full- and under-expansions. The jet sequences were visualized using a CCD camera. It was found that the injection of supersonic air jets into water is always accompanied by strong flow oscillation, which is related to the phenomenon of shock waves feedback in the gas phase. The shock wave feedback is different from the acoustic feedback when a supersonic gas jet discharges into open air, which causes screech tone. It is a process that the shock waves enclosed in the gas pocket induce a periodic pressure with large amplitude variation in the gas jet. Consequently, the periodic pressure causes the jet oscillation including the large amplitude expansion. Detailed pressure measurements were also conducted to verify the shock wave feedback phenomenon. Three kinds of measuring methods were used, i.e., pressure probe submerged in water, pressure measurements from the side and front walls of the nozzle devices respectively. The results measured by these methods are in a good agreement. They show that every oscillation of the jets causes a sudden increase of pressure and the average frequency of the shock wave feedback is about 5-10 Hz.

  14. Research on the mechanics of underwater supersonic gas jets

    Institute of Scientific and Technical Information of China (English)

    2010-01-01

    An experimental research was carried out to study the fluid mechanics of underwater supersonic gas jets. High pressure air was injected into a water tank through converging-diverging nozzles (Laval nozzles). The jets were operated at different conditions of over-, full- and under-expansions. The jet sequences were visualized using a CCD camera. It was found that the injection of supersonic air jets into water is always accompanied by strong flow oscillation, which is related to the phenomenon of shock waves feedback in the gas phase. The shock wave feedback is different from the acoustic feedback when a supersonic gas jet discharges into open air, which causes screech tone. It is a process that the shock waves enclosed in the gas pocket induce a periodic pressure with large amplitude variation in the gas jet. Consequently, the periodic pressure causes the jet oscillation including the large amplitude expansion. Detailed pressure measurements were also conducted to verify the shock wave feedback phenomenon. Three kinds of measuring methods were used, i.e., pressure probe submerged in water, pressure measurements from the side and front walls of the nozzle devices respectively. The results measured by these methods are in a good agreement. They show that every oscillation of the jets causes a sudden increase of pressure and the average frequency of the shock wave feedback is about 5–10 Hz.

  15. A new gaseous detector- micro mesh gaseous structure

    Institute of Scientific and Technical Information of China (English)

    TANG Hao-Hui; GUO Jun-Jun; WANG Xiao-Lian; XU Zi-Zong

    2009-01-01

    The structure and working principle of Micromegas (MICRO Mesh Gaseous Structure) is discussed. Some radiation sources of a and X rays are used to test this detector. The optimized electric-field intensity of the conversion gap is obtained. The transmission of electrons and the uniformity of the amplification gap are also presented. The energy resolution of the 5.9 keV peak is better than 27%.

  16. Payload mass improvements of supersonic retropropulsive flight for human class missions to Mars

    Science.gov (United States)

    Fagin, Maxwell H.

    Supersonic retropropulsion (SRP) is the use of retrorockets to decelerate during atmospheric flight while the vehicle is still traveling in the supersonic/hypersonic flight regime. In the context of Mars exploration, subsonic retropropulsion has a robust flight heritage for terminal landing guidance and control, but all supersonic deceleration has, to date, been performed by non-propulsive (i.e. purely aerodynamic) methods, such as aeroshells and parachutes. Extending the use of retropropulsion from the subsonic to the supersonic regime has been identified as an enabling technology for high mass humans-to-Mars architectures. However, supersonic retropropulsion still poses significant design and control challenges, stemming mainly from the complex interactions between the hypersonic engine plumes, the oncoming air flow, and the vehicle's exterior surface. These interactions lead to flow fields that are difficult to model and produce counter intuitive behaviors that are not present in purely propulsive or purely aerodynamic flight. This study will provide an overview of the work done in the design of SRP systems. Optimal throttle laws for certain trajectories will be derived that leverage aero/propulsive effects to decrease propellant requirements and increase total useful landing mass. A study of the mass savings will be made for a 10 mT reference vehicle based on a propulsive version of the Orion capsule, followed by the 100 mT ellipsoid vehicle assumed by NASA's Mars Design Reference Architecture.

  17. Noise reduction in supersonic jets by nozzle fluidic inserts

    Science.gov (United States)

    Morris, Philip J.; McLaughlin, Dennis K.; Kuo, Ching-Wen

    2013-08-01

    Professor Philip Doak spent a very productive time as a consultant to the Lockheed-Georgia Company in the early 1970s. The focus of the overall research project was the prediction and reduction of noise from supersonic jets. Now, 40 years on, the present paper describes an innovative methodology and device for the reduction of supersonic jet noise. The goal is the development of a practical active noise reduction technique for low bypass ratio turbofan engines. This method introduces fluidic inserts installed in the divergent wall of a CD nozzle to replace hard-wall corrugation seals, which have been demonstrated to be effective by Seiner (2005) [1]. By altering the configuration and operating conditions of the fluidic inserts, active noise reduction for both mixing and shock noise has been obtained. Substantial noise reductions have been achieved for mixing noise in the maximum noise emission direction and in the forward arc for broadband shock-associated noise. To achieve these reductions (on the order of greater than 4 and 2 dB for the two main components respectively), practically achievable levels of injection mass flow rates have been used. The total injected mass flow rates are less than 4% of the core mass flow rate and the effective operating injection pressure ratio has been maintained at or below the same level as the nozzle pressure ratio of the core flow.

  18. On the Comparison of the Long Penetration Mode (LPM) Supersonic Counterflowing Jet to the Supersonic Screech Jet

    Science.gov (United States)

    Farr, Rebecca A.; Chang, Chau-Lyan.; Jones, Jess H.; Dougherty, N. Sam

    2015-01-01

    The authors provide a brief overview of the classic tonal screech noise problem created by underexpanded supersonic jets, briefly describing the fluid dynamic-acoustics feedback mechanism that has been long established as the basis for this well-known aeroacoustics problem. This is followed by a description of the Long Penetration Mode (LPM) supersonic underexpanded counterflowing jet phenomenon which has been demonstrated in several wind tunnel tests and modeled in several computational fluid dynamics (CFD) simulations. The authors provide evidence from test and CFD analysis of LPM that indicates that acoustics feedback and fluid interaction seen in LPM are analogous to the aeroacoustics interactions seen in screech jets. Finally, the authors propose applying certain methodologies to LPM which have been developed and successfully demonstrated in the study of screech jets and mechanically induced excitation in fluid oscillators for decades. The authors conclude that the large body of work done on jet screech, other aeroacoustic phenomena, and fluid oscillators can have direct application to the study and applications of LPM counterflowing supersonic cold flow jets.

  19. Microbial production of gaseous hydrocarbons

    Energy Technology Data Exchange (ETDEWEB)

    Fukuda, Hideo

    1987-10-20

    Microbial production of ethylene, isobutane and a saturated gaseous hydrocarbon mixture was described. Microbial ethylene production was studied with Penicillium digitatum IFO 9372 and a novel pathway of the ethylene biosynthesis through alpha-ketoglutarate was proposed. Rhodotorula minuta IFO 1102 was selected for the microbial production of isobutane and the interesting actions of L-leucine and L-phenylalanine for the isobutane production were found. It was finally presented about the microbial production of a saturated gaseous hydrocarbon mixture with Rhizopus japonicus IFO 4758 was described. A gas mixture was produced through a chemical reaction of SH compounds and some cellular component such as squalene under aerobic conditions. (4 figs, 7 tabs, 41 refs)

  20. Gaseous fuel nuclear reactor research

    Science.gov (United States)

    Schwenk, F. C.; Thom, K.

    1975-01-01

    Gaseous-fuel nuclear reactors are described; their distinguishing feature is the use of fissile fuels in a gaseous or plasma state, thereby breaking the barrier of temperature imposed by solid-fuel elements. This property creates a reactor heat source that may be able to heat the propellant of a rocket engine to 10,000 or 20,000 K. At this temperature level, gas-core reactors would provide the breakthrough in propulsion needed to open the entire solar system to manned and unmanned spacecraft. The possibility of fuel recycling makes possible efficiencies of up to 65% and nuclear safety at reduced cost, as well as high-thrust propulsion capabilities with specific impulse up to 5000 sec.

  1. Overexpanded viscous supersonic jet interacting with a unilateral barrier

    Science.gov (United States)

    Dobrynin, B. M.; Maslennikov, V. G.; Sakharov, V. A.; Serova, E. V.

    1986-07-01

    The interaction of a two-dimensional supersonic jet with a unilateral barrier parallel to the flow symmetry plane was studied to account for effects due to gas viscosity and backgound-gas ejection from the region into which the jet expands. In the present experiments, the incident shock wave was reflected at the end of a shock tube equipped with a nozzle. The jet emerged into a pressure chamber 6 cu m in volume and the environmental pressure ratio of the flow in the quasi-stationary phase remained constant. The light source was an OGM-20 laser operating in the giant-pulse mode. Due to background-gas ejection, the gas density in the vicinity of the barrier is much less than on the unconfined side of the jet. The resulting flow is characterized by two distinct environmental pressure ratios: the flow is underexpanded near the barrier, while on the other side it is overexpanded.

  2. Noise Trends of a 0.5 M (20 In.) Diameter Supersonic Throughflow Fan as Measured in an Unmodified Compressor Aerodynamic Test Facility

    Science.gov (United States)

    Dittmar, James H.; Hall, David G.; Moore, Royce D.

    1993-01-01

    The tone noise levels of a supersonic throughflow fan were measured at subsonic and supersonic axial duct Mach numbers. The noise in the inlet plenum showed no blade passing and harmonic tones at subsonic or supersonic axial flow conditions. At subsonic axial flow conditions, the supersonic throughflow fan showed no inlet plenum tones at fan operating conditions where tone noise had been previously measured for a subsonic fan design. This lower inlet-quadrant noise level for the supersonic throughflow fan was the result of high subsonic inlet velocities acting to reduce the noise propagating out the inlet. The fan noise, which was prevented from propagating upstream by the high subsonic inlet velocities, appeared to increase the noise in the exhaust duct at subsonic throughflow conditions. The exhaust duct noise decreased at supersonic axial throughflow Mach numbers, with the lowest blade passing and harmonic tones levels being observed at the design axial Mach number of 2.0. Multiple pure tone noise was observed in the inlet duct at subsonic axial flow Mach numbers but was seen only in the exhaust duct at supersonic axial flow conditions.

  3. Analyzing the structure of the optical path difference of the supersonic film cooling

    Science.gov (United States)

    Ding, Haolin; Yi, Shihe; Fu, Jia; He, Lin

    2016-10-01

    While high-speed aircraft are flying in the atmosphere, its optical-hood is subjected to severe aerodynamic heating. Supersonic film cooling method can effectively isolate external heating, but the flow structures formed by the supersonic film cooling can cause the beam degradation and affect the imaging quality. To research the aero-optics of supersonic film cooling, an experimental model was adopted in this paper, its mainstream Mach number 3.4, designed jet Mach number 2.5, measured jet Mach number 2.45. High-resolution images of flow were acquired by the nano-based planar laser scattering (NPLS) technique, by reconstructing the density field of supersonic film cooling, and then, the optical path difference (OPD) were acquired by the ray-tracing method. Depending on the comparison between K-H vortex and OPD distribution, the valleys of OPD correspond to the vortex `rollers' and the peaks to the `braids'. However, the corresponding relationship becomes quite irregular for the flow field with developed vortices, and cannot be summarized in this manner. And then, the OPD were analyzed by correlation function and structure function, show that, there is a relationship between the shape of OPD correlation function and the vortex structure, the correlation function type changed with the development of the vortex. The correctness that the mixing layer makes a main contribution to the aero-optics of supersonic film cooling was verified, and the structure function of aero-optical distortion has a power relationship that is similar to that of atmospheric optics. At last, the power spectrum corresponding to the typical region of supersonic film cooling were acquired by improved periodgram.

  4. Numerical analysis of Chevron nozzle effects on performance of the supersonic ejector-diffuser system

    Science.gov (United States)

    Kong, Fanshi; Jin, Yingzi; Setoguchi, Toshiaki; Kim, Heuy Dong

    2013-10-01

    The supersonic nozzle is the most important device of an ejector-diffuser system. The best operation condition and optimal structure of supersonic nozzle are hardly known due to the complicated turbulent mixing, compressibility effects and even flow unsteadiness which are generated around the nozzle extent. In the present study, the primary stream nozzle was redesigned using convergent nozzle to activate the shear actions between the primary and secondary streams, by means of longitudinal vortices generated between the Chevron lobes. Exactly same geometrical model of ejector-diffuser system was created to validate the results of experimental data. The operation characteristics of the ejector system were compared between Chevron nozzle and conventional convergent nozzle for the primary stream. A CFD method has been applied to simulate the supersonic flows and shock waves inside the ejector. It is observed that the flow structure and shock system were changed and primary numerical analysis results show that the Chevron nozzle achieve a positive effect on the supersonic ejector-diffuser system performance. The ejector with Chevron nozzle can entrain more secondary stream with less primary stream mass flow rate.

  5. Ongoing Validation of Computational Fluid Dynamics for Supersonic Retro-Propulsion

    Science.gov (United States)

    Schauerhamer, Guy; Trumble, Kerry; Carlson, Jan-Renee; Edquist, Karl; Buning, Pieter; Sozer, Emre

    2011-01-01

    During the Entry, Decent, and Landing phase of planetary exploration, previous methods of deceleration do not scale with high mass spacecraft. Supersonic Retro-Propulsion(SRP)is a viable method to decelerate large spacecraft including those that will carry humans to Mars. Flow data at these conditions are difficult to obtain through flight or wind tunnel experiments

  6. Automated sampling and control of gaseous simulations

    KAUST Repository

    Huang, Ruoguan

    2013-05-04

    In this work, we describe a method that automates the sampling and control of gaseous fluid simulations. Several recent approaches have provided techniques for artists to generate high-resolution simulations based on a low-resolution simulation. However, often in applications the overall flow in the low-resolution simulation that an animator observes and intends to preserve is composed of even lower frequencies than the low resolution itself. In such cases, attempting to match the low-resolution simulation precisely is unnecessarily restrictive. We propose a new sampling technique to efficiently capture the overall flow of a fluid simulation, at the scale of user\\'s choice, in such a way that the sampled information is sufficient to represent what is virtually perceived and no more. Thus, by applying control based on the sampled data, we ensure that in the resulting high-resolution simulation, the overall flow is matched to the low-resolution simulation and the fine details on the high resolution are preserved. The samples we obtain have both spatial and temporal continuity that allows smooth keyframe matching and direct manipulation of visible elements such as smoke density through temporal blending of samples. We demonstrate that a user can easily configure a simulation with our system to achieve desired results. © 2013 Springer-Verlag Berlin Heidelberg.

  7. Supersonic collisions between two gas streams

    CERN Document Server

    Lee, H M; Ryu, D; Lee, Hyung Mok; Kang, Hyesung; Ryu, Dongsu

    1995-01-01

    A star around a massive black hole can be disrupted tidally by the gravity of the black hole. Then, its debris may form a precessing stream which may even collide with itself. In order to understand the dynamical effects of the stream-stream collision on the eventual accretion of the stellar debris onto the black hole, we have studied how gas flow behaves when the outgoing stream collides supersonically with the incoming stream. We have investigated the problem analytically with one-dimensional plane-parallel streams and numerically with more realistic three-dimensional streams. A shock formed around the contact surface converts the bulk of the orbital streaming kinetic energy into thermal energy. In three-dimensional simulations, the accumulated hot post-shock gas then expands adiabatically and drives another shock into the low density ambient region. Through this expansion, thermal energy is converted back to the kinetic energy associated with the expanding motion. Thus, in the end, only a small fraction of...

  8. External-Compression Supersonic Inlet Design Code

    Science.gov (United States)

    Slater, John W.

    2011-01-01

    A computer code named SUPIN has been developed to perform aerodynamic design and analysis of external-compression, supersonic inlets. The baseline set of inlets include axisymmetric pitot, two-dimensional single-duct, axisymmetric outward-turning, and two-dimensional bifurcated-duct inlets. The aerodynamic methods are based on low-fidelity analytical and numerical procedures. The geometric methods are based on planar geometry elements. SUPIN has three modes of operation: 1) generate the inlet geometry from a explicit set of geometry information, 2) size and design the inlet geometry and analyze the aerodynamic performance, and 3) compute the aerodynamic performance of a specified inlet geometry. The aerodynamic performance quantities includes inlet flow rates, total pressure recovery, and drag. The geometry output from SUPIN includes inlet dimensions, cross-sectional areas, coordinates of planar profiles, and surface grids suitable for input to grid generators for analysis by computational fluid dynamics (CFD) methods. The input data file for SUPIN and the output file from SUPIN are text (ASCII) files. The surface grid files are output as formatted Plot3D or stereolithography (STL) files. SUPIN executes in batch mode and is available as a Microsoft Windows executable and Fortran95 source code with a makefile for Linux.

  9. Optimization on a Network-based Parallel Computer System for Supersonic Laminar Wing Design

    Science.gov (United States)

    Garcia, Joseph A.; Cheung, Samson; Holst, Terry L. (Technical Monitor)

    1995-01-01

    A set of Computational Fluid Dynamics (CFD) routines and flow transition prediction tools are integrated into a network based parallel numerical optimization routine. Through this optimization routine, the design of a 2-D airfoil and an infinitely swept wing will be studied in order to advance the design cycle capability of supersonic laminar flow wings. The goal of advancing supersonic laminar flow wing design is achieved by wisely choosing the design variables used in the optimization routine. The design variables are represented by the theory of Fourier series and potential theory. These theories, combined with the parallel CFD flow routines and flow transition prediction tools, provide a design space for a global optimal point to be searched. Finally, the parallel optimization routine enables gradient evaluations to be performed in a fast and parallel fashion.

  10. Application of POD on time-resolved schlieren in supersonic multi-stream rectangular jets

    Science.gov (United States)

    Berry, M. G.; Magstadt, A. S.; Glauser, M. N.

    2017-02-01

    In this paper, we present an experimental investigation of a supersonic rectangular nozzle with aft deck used for three-stream engines. The jet utilizes a single expansion ramp nozzle (SERN) configuration along with multiple streams, operating at a bulk flow Mj,1 = 1.6 and bypass stream Mj,3 = 1.0. This idealized representation consists of two canonical flows: a supersonic convergent-divergent (CD) jet and a sonic wall jet. Time-resolved schlieren experiments were performed up to 100 kHz. Proper orthogonal decomposition (POD), as suggested by Lumley for structure identification in turbulent flows, is applied to the schlieren images and the spatial eigenfunctions and time-dependent coefficients are related to the flow structures. This research seeks to lay a foundation for fundamental testing of multi-stream SERNs and the identification of the flow physics that dominate these modern military nozzles.

  11. Super-Sonic Turbulence in the Perseus Molecular Cloud

    CERN Document Server

    Padoan, P; Billawala, Y N; Juvela, M; Nordlund, A A; Padoan, Paolo; Bally, John; Billawala, Youssef; Juvela, Mika; Nordlund, AAke

    1999-01-01

    We compare the statistical properties of J=1-0 13CO spectra observed in the Perseus Molecular Cloud with synthetic J=1-0 13CO spectra, computed solving the non-LTE radiative transfer problem for a model cloud obtained as solutions of the three dimensional magneto-hydrodynamic (MHD) equations. The model cloud is a randomly forced super-Alfvenic and highly super-sonic turbulent isothermal flow. The purpose of the present work is to test if idealized turbulent flows, without self-gravity, stellar radiation, stellar outflows, or any other effect of star formation, are inconsistent or not with statistical properties of star forming molecular clouds. We present several statistical results that demonstrate remarkable similarity between real data and the synthetic cloud. Statistical properties of molecular clouds like Perseus are appropriately described by random super-sonic and super-Alfvenic MHD flows. Although the description of gravity and stellar radiation are essential to understand the formation of single prot...

  12. A compressible multiphase framework for simulating supersonic atomization

    Science.gov (United States)

    Regele, Jonathan D.; Garrick, Daniel P.; Hosseinzadeh-Nik, Zahra; Aslani, Mohamad; Owkes, Mark

    2016-11-01

    The study of atomization in supersonic combustors is critical in designing efficient and high performance scramjets. Numerical methods incorporating surface tension effects have largely focused on the incompressible regime as most atomization applications occur at low Mach numbers. Simulating surface tension effects in high speed compressible flow requires robust numerical methods that can handle discontinuities caused by both material interfaces and shocks. A shock capturing/diffused interface method is developed to simulate high-speed compressible gas-liquid flows with surface tension effects using the five-equation model. This includes developments that account for the interfacial pressure jump that occurs in the presence of surface tension. A simple and efficient method for computing local interface curvature is developed and an acoustic non-dimensional scaling for the surface tension force is proposed. The method successfully captures a variety of droplet breakup modes over a range of Weber numbers and demonstrates the impact of surface tension in countering droplet deformation in both subsonic and supersonic cross flows.

  13. Computer simulation and visualization of supersonic jet for gas cluster equipment

    Science.gov (United States)

    Ieshkin, A.; Ermakov, Y.; Chernysh, V.; Ivanov, I.; Kryukov, I.; Alekseev, K.; Kargin, N.; Insepov, Z.

    2015-09-01

    Supersonic nozzle is a key component of a gas cluster condensation system. We describe a flow visualization system using glow discharge with annular or plane electrodes. The geometric parameters of a supersonic jet under typical conditions used in a gas cluster ion beam accelerator are investigated. As well numerical simulations were performed. Dependence of inlet and ambient pressures and nozzle throat diameter on the shock bottle dimensions is described for different working gases. Influence of condensation rate on shock bottle axial size is discussed.

  14. Computer simulation and visualization of supersonic jet for gas cluster equipment

    Energy Technology Data Exchange (ETDEWEB)

    Ieshkin, A. [Faculty of Physics, Lomonosov Moscow State University, Leninskie Gory, Moscow 119991 (Russian Federation); Ermakov, Y. [Scobeltsyn Nuclear Physics Research Institute, Lomonosov State Moscow University, GSP-1, Leninskiye Gory, Moscow 119991 (Russian Federation); Chernysh, V.; Ivanov, I. [Faculty of Physics, Lomonosov Moscow State University, Leninskie Gory, Moscow 119991 (Russian Federation); Kryukov, I. [Institute for Problems in Mechanics, Russian Academy of Sciences, prosp. Vernadskogo, 101, Block 1, Moscow 119526 (Russian Federation); Alekseev, K.; Kargin, N. [National Research Nuclear University «MEPhI», Kashirskoye shosse 31, Moscow 115409 (Russian Federation); Insepov, Z., E-mail: zinsepov@purdue.edu [Purdue University, 500 Central Drive, West Lafayette, IN (United States); Nazarbayev University Research and Innovation System, Kabanbay Batyr Avenue 53, Astana (Kazakhstan)

    2015-09-21

    Supersonic nozzle is a key component of a gas cluster condensation system. We describe a flow visualization system using glow discharge with annular or plane electrodes. The geometric parameters of a supersonic jet under typical conditions used in a gas cluster ion beam accelerator are investigated. As well numerical simulations were performed. Dependence of inlet and ambient pressures and nozzle throat diameter on the shock bottle dimensions is described for different working gases. Influence of condensation rate on shock bottle axial size is discussed.

  15. Application of advanced computational codes in the design of an experiment for a supersonic throughflow fan rotor

    Science.gov (United States)

    Wood, Jerry R.; Schmidt, James F.; Steinke, Ronald J.; Chima, Rodrick V.; Kunik, William G.

    1987-01-01

    Increased emphasis on sustained supersonic or hypersonic cruise has revived interest in the supersonic throughflow fan as a possible component in advanced propulsion systems. Use of a fan that can operate with a supersonic inlet axial Mach number is attractive from the standpoint of reducing the inlet losses incurred in diffusing the flow from a supersonic flight Mach number to a subsonic one at the fan face. The design of the experiment using advanced computational codes to calculate the components required is described. The rotor was designed using existing turbomachinery design and analysis codes modified to handle fully supersonic axial flow through the rotor. A two-dimensional axisymmetric throughflow design code plus a blade element code were used to generate fan rotor velocity diagrams and blade shapes. A quasi-three-dimensional, thin shear layer Navier-Stokes code was used to assess the performance of the fan rotor blade shapes. The final design was stacked and checked for three-dimensional effects using a three-dimensional Euler code interactively coupled with a two-dimensional boundary layer code. The nozzle design in the expansion region was analyzed with a three-dimensional parabolized viscous code which corroborated the results from the Euler code. A translating supersonic diffuser was designed using these same codes.

  16. Inhalation gases or gaseous mediators as neuroprotectants for cerebral ischaemia.

    Science.gov (United States)

    Sutherland, Brad A; Harrison, Joanne C; Nair, Shiva M; Sammut, Ivan A

    2013-01-01

    Ischaemic stroke is one of the leading causes of morbidity and mortality worldwide. While recombinant tissue plasminogen activator can be administered to produce thrombolysis and restore blood flow to the ischaemic brain, therapeutic benefit is only achieved in a fraction of the subset of patients eligible for fibrinolytic intervention. Neuroprotective therapies attempting to restrict the extent of brain injury following cerebral ischaemia have not been successfully translated into the clinic despite overwhelming pre-clinical evidence of neuroprotection. Therefore, an adequate treatment for the majority of acute ischaemic stroke patients remains elusive. In the stroke literature, the use of therapeutic gases has received relatively little attention. Gases such as hyperbaric and normobaric oxygen, xenon, hydrogen, helium and argon all possess biological effects that have shown to be neuroprotective in pre-clinical models of ischaemic stroke. There are significant advantages to using gases including their relative abundance, low cost and feasibility for administration, all of which make them ideal candidates for a translational therapy for stroke. In addition, modulating cellular gaseous mediators including nitric oxide, carbon monoxide, and hydrogen sulphide may be an attractive option for ischaemic stroke therapy. Inhalation of these gaseous mediators can also produce neuroprotection, but this strategy remains to be confirmed as a viable therapy for ischaemic stroke. This review highlights the neuroprotective potential of therapeutic gas therapy and modulation of gaseous mediators for ischaemic stroke. The therapeutic advantages of gaseous therapy offer new promising directions in breaking the translational barrier for ischaemic stroke.

  17. Gaseous abundances in M82

    CERN Document Server

    Ranalli, P; Origlia, L; Maiolino, R; Makishima, K; Ranalli, Piero; Comastri, Andrea; Origlia, Livia; Maiolino, Roberto; Makishima, Kazuo

    2005-01-01

    We present the preliminary analysis of a deep (100ks) XMM-Newton observation of M82. The spatial distribution of the abundances of chemical elements (Fe, O, Ne, Mg, Si, S) is investigated through narrow-band imaging analisys and spatially-resolved spectroscopy. We find that the abundances of alpha-elements follow a bipolar distribution, these elements being more abundant in the gaseous outflow than in the galaxy centre. This behaviour is found to be more marked for lighter elements (O, Ne) than for heavier elements.

  18. Supersonic flutter analysis of thin cracked functionally graded material plates

    CERN Document Server

    Natarajan, S; Bordas, S

    2012-01-01

    In this paper, the flutter behaviour of simply supported square functionally graded material plates immersed in a supersonic flow is studied. An enriched 4-noded quadrilateral element based on field consistency approach is used for this study and the crack is modelled independent of the underlying mesh. The material properties are assumed to be temperature dependent and graded only in the thickness direction. The effective material properties are estimated using the rule of mixtures. The formulation is based on the first order shear deformation theory and the shear correction factors are evaluated employing the energy equivalence principle. The influence of the crack length, the crack orientation, the flow angle and the gradient index on the aerodynamic pressure and the frequency are numerically studied. The results obtained here reveal that the critical frequency and the critical pressure decreases with increase in crack length and it is minimum when the crack is aligned to the flow angle.

  19. Study on Turbulent Behavior of Water Jet in Supersonic Steam Injector

    Science.gov (United States)

    Fukuichi, Akira; Abe, Yutaka; Fujiwara, Akiko; Kawamoto, Yujiro; Iwaki, Chikako; Narabayashi, Tadashi; Mori, Michitsugu; Ohmori, Shuichi

    One of the most interesting devices for light water reactor systems aimed at simplified system, improvement of safety and reliability is a supersonic steam injector. Supersonic steam injector is a passive jet pump without rotating machine and high efficient heat exchanger because of direct contact condensation between supersonic steam and a subcooled water jet. It is considered that flow behavior in the supersonic steam injector is related to complicated turbulent flow with large shear stress induced by velocity difference between steam and water and direct contact condensation. However, studies about turbulent flow under large shear stress with direct contact condensation are not enough. Especially, mechanisms of momentum and heat transfer are not clarified in detail. Objective of the present study is to investigate turbulent behaviors of a water jet and interface that play an important role in heat transfer and momentum transfer. Radial distribution of streamwise velocity and fluctuation of total pressure are measured by a pitot measurement. Visual measurement of the turbulent water jet is conducted by a high speed camera in order to identify location of unstable interface and its behavior. It is found that streamwise velocity increases as it approaches downstream of the mixing nozzle. Fluctuation of total pressure is large at water-steam mixture region. It is confirmed that waves propagated on the interface. And its velocity is obtained.

  20. A parametric study on supersonic/hypersonic flutter behavior of aero-thermo-elastic geometrically imperfect curved skin panel

    NARCIS (Netherlands)

    Abbas, L.K.; Rui, X.; Marzocca, P.; Abdalla, M.; De Breuker, R.

    2011-01-01

    In this paper, the effect of the system parameters on the flutter of a curved skin panel forced by a supersonic/hypersonic unsteady flow is numerically investigated. The aeroelastic model investigated includes the third-order piston theory aerodynamics for modeling the flow-induced forces and the V

  1. Hydrogen and Gaseous Fuel Safety and Toxicity

    Energy Technology Data Exchange (ETDEWEB)

    Lee C. Cadwallader; J. Sephen Herring

    2007-06-01

    Non-traditional motor fuels are receiving increased attention and use. This paper examines the safety of three alternative gaseous fuels plus gasoline and the advantages and disadvantages of each. The gaseous fuels are hydrogen, methane (natural gas), and propane. Qualitatively, the overall risks of the four fuels should be close. Gasoline is the most toxic. For small leaks, hydrogen has the highest ignition probability and the gaseous fuels have the highest risk of a burning jet or cloud.

  2. On highly focused supersonic microjets

    CERN Document Server

    Tagawa, Yoshiyuki; Willem, Claas; Peters, Ivo R; van der Meer, Deveraj; Sun, Chao; Prosperetti, Andrea; Lohse, Detlef

    2011-01-01

    By focusing a laser pulse in a liquid-filled glass-microcapillary open at one end, a small mass of liquid is instantaneously vapourised. This leads to a shock wave which travels towards the concave free surface where it generates a high-speed microjet. The initial shape of the meniscus plays a dominant role in the process. The velocity of the jet can reach supersonic speeds up to 850\\,m/s while maintaining a very sharp geometry. The entire evolution of the jet is observed by high-speed recordings of up to $10^6\\,$fps. A parametric study of the jet velocity as a function of the contact angle of the liquid-glass interface, the energy absorbed by the liquid, the diameter of the capillary tube, and the distance between the laser focus and the free surface is performed, and the results are rationalised. The method could be used for needle-free injection of vaccines or drugs.

  3. Supersonic Cloud Collision-II

    CERN Document Server

    Anathpindika, S

    2009-01-01

    In this, second paper of the sequel of two papers, we present five SPH simulations of fast head-on cloud collisions and study the evolution of the ram pressure confined gas slab. Anathpindika (2008) (hereafter paper I) considered highly supersonic cloud collisions and examined the effect of bending and shearing instabilities on the shocked gas slab. The post-collision shock here, as in paper I, is also modelled by a simple barotropic equation of state (EOS). However, a much stiffer EOS is used to model the shock resulting from a low velocity cloud collision. We explore the parameter space by varying the pre-collision velocity and the impact parameter. We observe that pressure confined gas slabs become Jeans unstable if the sound crossing time, $t_{cr}$, is much larger than the freefall time, $t_{ff}$, of putative clumps condensing out of them. Self gravitating clumps may spawn multiple/larger $N$-body star clusters. We also suggest that warmer gas slabs are unlikely to fragment and may end up as diffuse gas c...

  4. Method of producing gaseous products using a downflow reactor

    Energy Technology Data Exchange (ETDEWEB)

    Cortright, Randy D; Rozmiarek, Robert T; Hornemann, Charles C

    2014-09-16

    Reactor systems and methods are provided for the catalytic conversion of liquid feedstocks to synthesis gases and other noncondensable gaseous products. The reactor systems include a heat exchange reactor configured to allow the liquid feedstock and gas product to flow concurrently in a downflow direction. The reactor systems and methods are particularly useful for producing hydrogen and light hydrocarbons from biomass-derived oxygenated hydrocarbons using aqueous phase reforming. The generated gases may find used as a fuel source for energy generation via PEM fuel cells, solid-oxide fuel cells, internal combustion engines, or gas turbine gensets, or used in other chemical processes to produce additional products. The gaseous products may also be collected for later use or distribution.

  5. Long flexible transfer lines for gaseous and liquid helium

    CERN Document Server

    Laeger, H; Rohner, P

    1978-01-01

    Screened flexible four-fold coaxial transfer lines for gaseous and liquid helium with lengths of 5 to 50 m have been successfully built and tested. The lines for gaseous helium have to supply and return a mass flow of 5 to 10 g s−1 at temperatures ranging between 350 and 20 K for cooldown or warmup of superconducting magnets. The lines for liquid helium have to supply up to 100 ℓ h−1 for final cooldown or up to 25 ℓ h−1 for normal operation of superconducting magnets. The hydrodynamic and thermal performance characteristics of the lines have been measured. The results are encouraging and it can be envisaged to use this kind of lines for superconducting magnets in high energy accelerators.

  6. Silent and Efficient Supersonic Bi-Directional Flying Wing Project

    Data.gov (United States)

    National Aeronautics and Space Administration — We propose a Phase I study for a novel concept of a supersonic bi-directional (SBiDir) flying wing (FW) that has the potential to revolutionize supersonic flight...

  7. Numerical modelling of Mars supersonic disk-gap-band parachute inflation

    Science.gov (United States)

    Gao, Xinglong; Zhang, Qingbin; Tang, Qiangang

    2016-06-01

    The transient dynamic behaviour of supersonic disk-gap-band parachutes in a Mars entry environment involving fluid structure interactions is studied. Based on the multi-material Arbitrary Lagrange-Euler method, the coupling dynamic model between a viscous compressible fluid and a flexible large deformation structure of the parachute is solved. The inflation performance of a parachute with a fixed forebody under different flow conditions is analysed. The decelerating parameters of the parachute, including drag area, opening loads, and coefficients, are obtained from the supersonic wind tunnel test data from NASA. Meanwhile, the evolution of the three-dimensional shape of the disk-gap-band parachute during supersonic inflation is presented, and the structural dynamic behaviour of the parachute is predicted. Then, the influence of the presence of the capsule on the flow field of the parachute is investigated, and the wake of unsteady fluid and the distribution of shock wave around the supersonic parachute are presented. Finally, the structural dynamic response of the canopy fabric under high-pressure conditions is comparatively analysed. The results show that the disk-gap-band parachute is well inflated without serious collapse. As the Mach numbers increase from 2.0 to 2.5, the drag coefficients gradually decrease, along with a small decrease in inflation time, which corresponds with test results, and proves the validity of the method proposed in this paper.

  8. Performance of Several High Order Numerical Methods for Supersonic Combustion

    Science.gov (United States)

    Sjoegreen, Bjoern; Yee, H. C.; Don, Wai Sun; Mansour, Nagi N. (Technical Monitor)

    2001-01-01

    The performance of two recently developed numerical methods by Yee et al. and Sjoegreen and Yee using postprocessing nonlinear filters is examined for a 2-D multiscale viscous supersonic react-live flow. These nonlinear filters can improve nonlinear instabilities and at the same time can capture shock/shear waves accurately. They do not, belong to the class of TVD, ENO or WENO schemes. Nevertheless, they combine stable behavior at discontinuities and detonation without smearing the smooth parts of the flow field. For the present study, we employ a fourth-order Runge-Kutta in time and a sixth-order non-dissipative spatial base scheme for the convection and viscous terms. We denote the resulting nonlinear filter schemes ACM466-RK4 and WAV66-RK4.

  9. Modeling supersonic combustion using a fully-implicit numerical method

    Science.gov (United States)

    Maccormack, Robert W.; Wilson, Gregory J.

    1990-01-01

    A fully-implicit finite-volume algorithm for two-dimensional axisymmetric flows has been coupled to a detailed hydrogen-air reaction mechanism (13 species and 33 reactions) so that supersonic combustion phenomena may be investigated. Numerical computations are compared with ballistic-range shadowgraphs of Lehr (1972) that exhibit two discontinuities caused by a blunt body as it passes through a premixed stoichiometric hydrogen-air mixture. The suitability of the numerical procedure for simulating these double-front flows is shown. The requirements for the physical formulation and the numerical modeling of these flowfields are discussed. Finally, the sensitivity of these external flowfields to changes in certain key reaction rate constants is examined.

  10. Electron ionization LC-MS with supersonic molecular beams--the new concept, benefits and applications.

    Science.gov (United States)

    Seemann, Boaz; Alon, Tal; Tsizin, Svetlana; Fialkov, Alexander B; Amirav, Aviv

    2015-11-01

    A new type of electron ionization LC-MS with supersonic molecular beams (EI-LC-MS with SMB) is described. This system and its operational methods are based on pneumatic spray formation of the LC liquid flow in a heated spray vaporization chamber, full sample thermal vaporization and subsequent electron ionization of vibrationally cold molecules in supersonic molecular beams. The vaporized sample compounds are transferred into a supersonic nozzle via a flow restrictor capillary. Consequently, while the pneumatic spray is formed and vaporized at above atmospheric pressure the supersonic nozzle backing pressure is about 0.15 Bar for the formation of supersonic molecular beams with vibrationally cold sample molecules without cluster formation with the solvent vapor. The sample compounds are ionized in a fly-though EI ion source as vibrationally cold molecules in the SMB, resulting in 'Cold EI' (EI of vibrationally cold molecules) mass spectra that exhibit the standard EI fragments combined with enhanced molecular ions. We evaluated the EI-LC-MS with SMB system and demonstrated its effectiveness in NIST library sample identification which is complemented with the availability of enhanced molecular ions. The EI-LC-MS with SMB system is characterized by linear response of five orders of magnitude and uniform compound independent response including for non-polar compounds. This feature improves sample quantitation that can be approximated without compound specific calibration. Cold EI, like EI, is free from ion suppression and/or enhancement effects (that plague ESI and/or APCI) which facilitate faster LC separation because full separation is not essential. The absence of ion suppression effects enables the exploration of fast flow injection MS-MS as an alternative to lengthy LC-MS analysis. These features are demonstrated in a few examples, and the analysis of the main ingredients of Cannabis on a few Cannabis flower extracts is demonstrated. Finally, the advantages of

  11. Stability of a laminar premixed supersonic free shear layer with chemical reactions

    Science.gov (United States)

    Menon, S.; Anderson, J. D., Jr.; Pai, S. I.

    1984-01-01

    The stability of a two-dimensional compressible supersonic flow in the wake of a flat plate is discussed. The fluid is a multi-species mixture which is undergoing finite rate chemical reactions. The spatial stability of an infinitesimal disturbance in the fluid is considered. Numerical solutions of the eigenvalue stability equations for both reactive and nonreactive supersonic flows are presented and discussed. The chemical reactions have significant influence on the stability behavior. For instance, a neutral eigenvalue is observed near the freestream Mach number of 2.375 for the nonreactive case, but disappears when the reaction is turned on. For reactive flows, the eigenvalues are not very dependent on the free stream Mach number.

  12. Supersonic combustion engine testbed, heat lightning

    Science.gov (United States)

    Hoying, D.; Kelble, C.; Langenbahn, A.; Stahl, M.; Tincher, M.; Walsh, M.; Wisler, S.

    1990-01-01

    The design of a supersonic combustion engine testbed (SCET) aircraft is presented. The hypersonic waverider will utilize both supersonic combustion ramjet (SCRAMjet) and turbofan-ramjet engines. The waverider concept, system integration, electrical power, weight analysis, cockpit, landing skids, and configuration modeling are addressed in the configuration considerations. The subsonic, supersonic and hypersonic aerodynamics are presented along with the aerodynamic stability and landing analysis of the aircraft. The propulsion design considerations include: engine selection, turbofan ramjet inlets, SCRAMjet inlets and the SCRAMjet diffuser. The cooling requirements and system are covered along with the topics of materials and the hydrogen fuel tanks and insulation system. A cost analysis is presented and the appendices include: information about the subsonic wind tunnel test, shock expansion calculations, and an aerodynamic heat flux program.

  13. The hydrodynamic stability of gaseous cosmic filaments

    CERN Document Server

    Birnboim, Yuval; Zinger, Elad

    2016-01-01

    Virial shocks at edges of cosmic-web structures are a clear prediction of standard structure formation theories. We derive a criterion for the stability of the post-shock gas and of the virial shock itself in spherical, filamentary and planar infall geometries. When gas cooling is important, we find that shocks become unstable, and gas flows uninterrupted towards the center of the respective halo, filament or sheet. For filaments, we impose this criterion on self-similar infall solutions. We find that instability is expected for filament masses between $10^{11}-10^{13}M_\\odot Mpc^{-1}.$ Using a simplified toy model, we then show that these filaments will likely feed halos with $10^{10}M_{\\odot}\\lesssim M_{halo}\\lesssim 10^{13}M_{\\odot}$ at redshift $z=3$, as well as $10^{12}M_{\\odot}\\lesssim M_{halo}\\lesssim 10^{15}M_{\\odot}$ at $z=0$. The instability will affect the survivability of the filaments as they penetrate gaseous halos in a non-trivial way. Additionally, smaller halos accreting onto non-stable filam...

  14. Supersonic Stall Flutter of High Speed Fans. [in turbofan engines

    Science.gov (United States)

    Adamczyk, J. J.; Stevens, W.; Jutras, R.

    1981-01-01

    An analytical model is developed for predicting the onset of supersonic stall bending flutter in axial flow compressors. The analysis is based on a modified two dimensional, compressible, unsteady actuator disk theory. It is applied to a rotor blade row by considering a cascade of airfoils whose geometry and dynamic response coincide with those of a rotor blade element at 85 percent of the span height (measured from the hub). The rotor blades are assumed to be unshrouded (i.e., free standing) and to vibrate in their first flexural mode. The effects of shock waves and flow separation are included in the model through quasi-steady, empirical, rotor total-pressure-loss and deviation-angle correlations. The actuator disk model predicts the unsteady aerodynamic force acting on the cascade blading as a function of the steady flow field entering the cascade and the geometry and dynamic response of the cascade. Calculations show that the present model predicts the existence of a bending flutter mode at supersonic inlet Mach numbers. This flutter mode is suppressed by increasing the reduced frequency of the system or by reducing the steady state aerodynamic loading on the cascade. The validity of the model for predicting flutter is demonstrated by correlating the measured flutter boundary of a high speed fan stage with its predicted boundary. This correlation uses a level of damping for the blade row (i.e., the log decrement of the rotor system) that is estimated from the experimental flutter data. The predicted flutter boundary is shown to be in good agreement with the measured boundary.

  15. Gaseous phase coal surface modification

    Energy Technology Data Exchange (ETDEWEB)

    Okoh, J.M.; Pinion, J.; Thiensatit, S.

    1992-05-07

    In this report, we present an improved, feasible and potentially cost effective method of cleaning and beneficiating ultrafine coal. Increased mechanization of mining methods and the need towards depyritization, and demineralization have led to an increase in the quantity of coal fines generated in recent times. For example, the amount of {minus}100 mesh coal occurring in coal preparation plant feeds now typically varies from 5 to 25% of the total feed. Environmental constraints coupled with the greatly increased cost of coal have made it increasingly important to recover more of these fines. Our method chemically modifies the surface of such coals by a series of gaseous phase treatments employing Friedel-Crafts reactions. By using olefins (ethene, propene and butene) and hydrogen chloride catalyst at elevated temperature, the surface hydrophobicity of coal is enhanced. This increased hydrophobicity is manifest in surface phenomena which reflect conditions at the solid/liquid interphase (zeta potential) and those which reflect conditions at the solid/liquid/gas interphases (contact angle, wettability and floatability).

  16. Experimental and numerical investigation of an air to air supersonic ejector for propulsion of a small supersonic wind tunnel

    Directory of Open Access Journals (Sweden)

    Kracík Jan

    2015-01-01

    Full Text Available The article deals with experimental and numerical investigation of an air to air supersonic ejector with twelve primary nozzles. The ejector is supposed to be used for propulsion of a small experimental supersonic wind tunnel which is situated in laboratories of Technical University of Liberec. A novel arrangement with 12 primary nozzles is used. The nozzles are placed at the periphery of the mixing chamber. The secondary stream enters the ejector through the free centre of the mixing chamber and is sucked into the space between the primary nozzles. Moreover the declination of the primary nozzles towards to ejector axis is 8.2° and the shape of the mixing chamber and diffuser walls is given by normal cubic spline function, which was investigated in previous work. The declination of the primary nozzles is supposed to eliminate reversal flow in the centre of the mixing chamber. Experimental results for different numbers of simultaneously activated primary nozzles are carried out. Experimental results are compared to the numerical simulation made with the help of Ansys Fluent software.

  17. Supersonic Virtual Valve Design for Numerical Simulation of a Large-Bore Natural Gas Engine

    Energy Technology Data Exchange (ETDEWEB)

    Kim, G.-H.; Kirkpatrick, A.; Mitchell, C.

    2007-10-01

    In many applications of supersonic injection devices, three-dimensional computation that can model a complex supersonic jet has become critical. However, in spite of its increasing necessity, it is computationally costly to capture the details of supersonic structures in intricate three-dimensional geometries with moving boundaries. In large-bore stationary natural gas fueled engine research, one of the most promising mixing enhancement technologies currently used for natural gas engines is high-pressure fuel injection. Consequently, this creates considerable interest in three-dimensional computational simulations that can examine the entire injection and mixing process in engines using high-pressure injection and can determine the impact of injector design on engine performance. However, the cost of three-dimensional engine simulations-including a moving piston and the kinetics of combustion and pollutant production quickly becomes considerable in terms of simulation time requirements. One limiting factor is the modeling of the small length scales of the poppet valve flow. Such length scales can be three orders of magnitude smaller than cylinder length scales. The objective of this paper is to describe the development of a methodology for the design of a simple geometry supersonic virtual valve that can be substituted in three-dimensional numerical models for the complex shrouded poppet valve injection system actually installed in the engine to be simulated.

  18. Conditions for supersonic bent Marshak waves

    CERN Document Server

    Xu, Qiang; Li, Jing; Dan, Jia-kun; Wang, Kun-lun; Zhou, Shao-tong

    2014-01-01

    Supersonic radiation diffusion approximation is a useful way to study the radiation transportation. Considering the bent Marshak wave theory in 2-dimensions, and an invariable source temperature, we get the supersonic radiation diffusion conditions which are about the Mach number $M>8(1+\\sqrt{\\ep})/3$, and the optical depth $\\tau>1$. A large Mach number requires a high temperature, while a large optical depth requires a low temperature. Only when the source temperature is in a proper region these conditions can be satisfied. Assuming the material opacity and the specific internal energy depend on the temperature and the density as a form of power law, for a given density, these conditions correspond to a region about source temperature and the length of the sample. This supersonic diffusion region involves both lower and upper limit of source temperature, while that in 1-dimension only gives a lower limit. Taking $\\rm SiO_2$ and the Au for example, we show the supersonic region numerically.

  19. Dielectric barrier discharge source for supersonic beams

    Energy Technology Data Exchange (ETDEWEB)

    Luria, K.; Lavie, N.; Even, U. [Sackler School of Chemistry, Tel Aviv University, Tel Aviv 69978 (Israel)

    2009-10-15

    We present a new excitation source for pulsed supersonic beams. The excitation is based on dielectric barrier discharge in the beam. It produces cold beams of metastable atoms, dissociated neutral atoms from molecular precursors, and both positive and negative ions with high efficiency and reliability.

  20. Initiation of Explosives From the Bow Shock of a Supersonic Penetrator

    Science.gov (United States)

    Ferm, Eric

    2009-06-01

    An analytic and computational study of supersonic penetration of an explosive is presented. The goal is the development of an initiation criterion relating projectile diameter and threshold projectile velocity determined by fundamental material and explosive parameters. The basis of the initiation criterion is an examination of the steady flow structure around a supersonic penetrator in the unreacted materials, yielding the states along the bow shock and the size and sonic character of the flow structure. The state is used to determine the time scale of the reacting explosive using initiation experiment results (Pop Plot). The size of the subsonic region is compared to the failure diameter to examine the viability of the initiation. The results are compared with experimental initiation criterion.

  1. Effect of Ablation on Heat Transfer & Performance of an Axisymmetric Supersonic Nozzle

    Science.gov (United States)

    Raza, M. A.

    The theoretical prediction of heat transfer effects in compressible turbulent flows is fundamentally complex phenomenon. Computational fluid dynamics (CFD) analysis is employed using Baldwin-Lomax turbulent model to simulate the effect of various nozzle geometry defects on the heat transfer state in supersonic nozzles. The study is done in terms of various heat transfer correlations and analogies by characteristic flow regimes numbers. Theses are calculated from modified Reynolds analogy for laminar flow over flat plate, the Dittus-Boelter correlation for fully developed turbulent flow, Sieder-Tate correlation for turbulent pipe flow with property variation and Bartz correlation for variable cross sections flow. In addition to these, modified Stanton correlation for high speed flows for pipe flow analogy is also used. The contribution of ablation on the formation of new nozzle contours at various regions is simulated using energy equation for charring ablators. The effect of heat transfer correlations on nozzle performance with various geometrical defects is also discussed. In addition to it, the supersonic flow behavior is also simulated in the nozzles in terms of pressure, temperature, Mach number and density distribution with ablated surfaces.

  2. Gaseous hydrogen production by water dissociation method

    Energy Technology Data Exchange (ETDEWEB)

    Lipovetsky, V.

    2003-04-01

    Gaseous hydrogen production is based on employment of the water dissociation process, intensified by action of a high water temperature and increase of the minus electric field, as a factor for water dissociation instead of electric current used in electrolysis. The water dissociation method makes it possible to produce concurrently both gaseous hydrogen and electric power in the operating reactor. The main power type used is thermal. (Author)

  3. Measurements of leading edge vortices in a supersonic stream

    Science.gov (United States)

    Milanovic, Ivana Milija

    An experimental investigation of the leading edge vortices from a 75° sweptback, sharp edge delta wing has been carried out in a Mach 2.49 stream. Five-hole conical probe traverses were conducted vertically and horizontally through the primary vortices at the trailing edge and at one half chord downstream station for 7° and 12° angles of attack. The main objective was to determine the Mach number and pressure distributions in the primary vortex and to present comparisons of flow properties at different survey stations. In response to the continued interest in efficient supersonic flight vehicles, particularly in the missile arena, the motivation for this research has been to provide the quantitative details of supersonic leading edge vortices, the understanding of which up to now has been largely based on flow visualizations and presumed similarity to low speed flows. As a prerequisite to the measurement campaign, the employed five-hole conical probe was numerically calibrated using a three-dimensional Thin Layer Navier-Stokes solver in order to circumvent the traditional experimental approach vastly demanding on resources. The pressure readings at the probe orifices were computed for a range of Mach numbers and pitch angles, and subsequently verified in wind tunnel tests. The calibration phase also demonstrated the profound influence of the probe bluntness on the nearby static pressure ports, its relevance to the ultimate modeling strategy and the resulting calibration charts. Flow diagnostics of the leading edge vortices included both qualitative flow visualizations, as well as quantitative measurements. Shadowgraphs provided information regarding the trajectory and relative size of the generated vortices while assuring that no probe-induced vortex breakdown occurred. Surface oil patterns revealed the general spanwise locations of leeward vortices, and confirmed topological similarity to their low speed counterparts. The probe measurements revealed substantial

  4. 7th International Symposium on Gaseous Dielectrics

    CERN Document Server

    James, David

    1994-01-01

    The Seventh International Symposium on Gaseous Dielectrics was held in Knoxville, Tennessee, U. S. A. , on April 24-28, 1994. The symposium continued the interdisciplinary character and comprehensive approach of the preceding six symposia. Gaseous DielecIries VII is a detailed record of the symposium proceedings. It covers recent advances and developments in a wide range of basic, applied and industrial areas of gaseous dielectrics. It is hoped that Gaseous DielecIries VII will aid future research and development in, and encourage wider industrial use of, gaseous dielectrics. The Organizing Committee of the Seventh International Symposium on Gaseous Dielectrics consisted of G. Addis (U. S. A. ), L. G. Christophorou (U. S. A. ), F. Y. Chu (Canada), A. H. Cookson (U. S. A. ), O. Farish (U. K. ), I. Gallimberti (Italy) , A. Garscadden (U. S. A. ), D. R. James (U. S. A. ), E. Marode (France), T. Nitta (Japan), W. Pfeiffer (Germany), Y. Qiu (China), I. Sauers (U. S. A. ), R. J. Van Brunt (U. S. A. ), and W. Zaengl...

  5. Findings from the Supersonic Qualification Program of the Mars Science Laboratory Parachute System

    Science.gov (United States)

    Sengupta, Anita; Steltzner, Adam; Witkowski, Allen; Candler, Graham; Pantano, Carlos

    2009-01-01

    supersonic wind tunnel testing of a rigid DGB parachute with entry-vehicle to validate two high fidelity computational fluid dynamics (CFD) tools. The computer codes utilized Large Eddy Simulation and Detached Eddy Simulation numerical approaches to accurately capture the turbulent wake of the entry vehicle and its coupling to the parachute bow-shock. The second phase was the development of fluid structure interaction (FSI) computational tools to predict parachute response to the supersonic flow field. The FSI development included the integration of the CFD from the first phase with a finite element structural model of the parachute membrane and cable elements. In this phase, a 4% of full-scale supersonic flexible parachute test program was conducted to provide validation data to the FSI code and an empirical dataset of the MSL parachute in a flight-like environment. The final phase is FSI simulations of the full-scale MSL parachute in a Mars type deployment. Findings from this program will be presented in terms of code development and validation, empirical findings from the supersonic testing, and drag performance during supersonic operation.

  6. Improved method of analyzing hot-wire measurements in supersonic turbulence

    Science.gov (United States)

    Logan, Pamela

    1989-01-01

    The present analysis method for hot-wire data in supersonic turbulence takes sound field effects into account and yields greater accuracy in its treatment of flow variable fluctuations than existing methods despite requiring only a moderately accurate estimate of static pressure fluctuations. The method demonstrates the way in which neglecting pressure fluctuations will affect hot-wire data analysis, as well as indicating the probable direction the errors will take.

  7. Supersonic jets of hydrogen and helium for laser wakefield acceleration

    CERN Document Server

    Svensson, K.; Wojda, F.; Senje, L.; Burza, M.; Aurand, B.; Genoud, G.; Persson, A.; Wahlström, C.-G.; Lundh, O.

    2016-01-01

    The properties of laser wakefield accelerated electrons in supersonic gas flows of hydrogen and helium are investigated. At identical backing pressure, we find that electron beams emerging from helium show large variations in their spectral and spatial distributions, whereas electron beams accelerated in hydrogen plasmas show a higher degree of reproducibility. In an experimental investigation of the relation between neutral gas density and backing pressure, it is found that the resulting number density for helium is ∼30% higher than for hydrogen at the same backing pressure. The observed differences in electron beam properties between the two gases can thus be explained by differences in plasma electron density. This interpretation is verified by repeating the laser wakefield acceleration experiment using similar plasma electron densities for the two gases, which then yielded electron beams with similar properties.

  8. Gas dynamics of a supersonic radial jet. Part II

    Science.gov (United States)

    Kosarev, V. F.; Klinkov, S. V.; Zaikovskii, V. N.

    2016-05-01

    The paper presents the radial distributions of the pressure measured with a Pitot tube for the case of a radial jet with/without swirling of the input flow in the pre-chamber; the length of the supersonic part of the jet, dependency of the jet thickness as a function of the distance from the nozzle outlet, and approximating analytical formula for the jet thickness that generalizes the experimental data. Experimental data demonstrated that at the deposition distances lower than 4-6 gauges from the nozzle outlet, the solid particle velocity and temperature are almost uniform over the jet cross section. This means that the target surface can be allocated here without loss in coating quality and deposition coefficient. The maximal recommended distance where the deposition is still possible is the length of l s0 ~ 16 gauges.

  9. Nonlinear closures for scale separation in supersonic magnetohydrodynamic turbulence

    CERN Document Server

    Grete, Philipp; Schmidt, Wolfram; Schleicher, Dominik R G; Federrath, Christoph

    2015-01-01

    Turbulence in compressible plasma plays a key role in many areas of astrophysics and engineering. The extreme plasma parameters in these environments, e.g. high Reynolds numbers, supersonic and super-Alfvenic flows, however, make direct numerical simulations computationally intractable even for the simplest treatment -- magnetohydrodynamics (MHD). To overcome this problem one can use subgrid-scale (SGS) closures -- models for the influence of unresolved, subgrid-scales on the resolved ones. In this work we propose and validate a set of constant coefficient closures for the resolved, compressible, ideal MHD equations. The subgrid-scale energies are modeled by Smagorinsky-like equilibrium closures. The turbulent stresses and the electromotive force (EMF) are described by expressions that are nonlinear in terms of large scale velocity and magnetic field gradients. To verify the closures we conduct a priori tests over 137 simulation snapshots from two different codes with varying ratios of thermal to magnetic pre...

  10. Fluid-structure interaction of panel in supersonic fluid passage

    Institute of Scientific and Technical Information of China (English)

    LIU Zhan-sheng; ZHANG Yun-feng; TIAN Xin

    2008-01-01

    Fluid-structure interaction of panel in supersonic fluid passage is studied with subcycling and spline interpolation based predict-correct scheme.The passage is formed with two parallel panels,one is risid and the other is flexible.The interaction between fluid flows and flexible panel is numerically studied,mainly focused on the effect of dynamic pressure and distance between two parallel panels.Subcycling and spline interpolation based predict-correct scheme is utihzed to combine the vibration and fluid analysis and to stabilize long-term calculations to get accurate resuhs.It's demonstrated that the flutter characteristic of flexible panel is more complex with the increase of dynamic pressure and the decrease of distance between two parallel panels.Via analyzing the propagation and reflection of disturbance in passage,it's determined as a main cause of the variations.

  11. Increased Mach Number Capability for the NASA Glenn 10x10 Supersonic Wind Tunnel

    Science.gov (United States)

    Slater, J. W.; Saunders, J. D.

    2015-01-01

    Computational simulations and wind tunnel testing were conducted to explore the operation of the Abe Silverstein Supersonic Wind Tunnel at the NASA Glenn Research Center at test section Mach numbers above the current limit of Mach 3.5. An increased Mach number would enhance the capability for testing of supersonic and hypersonic propulsion systems. The focus of the explorations was on understanding the flow within the second throat of the tunnel, which is downstream of the test section and is where the supersonic flow decelerates to subsonic flow. Methods of computational fluid dynamics (CFD) were applied to provide details of the shock boundary layer structure and to estimate losses in total pressure. The CFD simulations indicated that the tunnel could be operated up to Mach 4.0 if the minimum width of the second throat was made smaller than that used for previous operation of the tunnel. Wind tunnel testing was able to confirm such operation of the tunnel at Mach 3.6 and 3.7 before a hydraulic failure caused a stop to the testing. CFD simulations performed after the wind tunnel testing showed good agreement with test data consisting of static pressures along the ceiling of the second throat. The CFD analyses showed increased shockwave boundary layer interactions, which was also observed as increased unsteadiness of dynamic pressures collected in the wind tunnel testing.

  12. A computer program for the calculation of the flow field in supersonic mixed-compression inlets at angle of attack using the three-dimensional method of characteristics with discrete shock wave fitting

    Science.gov (United States)

    Vadyak, J.; Hoffman, J. D.; Bishop, A. R.

    1978-01-01

    The calculation procedure is based on the method of characteristics for steady three-dimensional flow. The bow shock wave and the internal shock wave system were computed using a discrete shock wave fitting procedure. The general structure of the computer program is discussed, and a brief description of each subroutine is given. All program input parameters are defined, and a brief discussion on interpretation of the output is provided. A number of sample cases, complete with data deck listings, are presented.

  13. Damping insert materials for settling chambers of supersonic wind tunnels

    Science.gov (United States)

    Wu, Jie; Radespiel, Rolf

    2017-03-01

    This study describes the application of a novel damping insert material for reducing the flow fluctuations in a tandem nozzle supersonic wind tunnel. This new damping material is composed of multi-layer stainless steel wired meshes. The influences of the multi-layer mesh, such as the quantity of the mesh layer and the installed location in the settling chamber, to the freestream quality have been investigated. A Pitot probe instrumented with a Kulite pressure sensor and a hot-wire probe are employed to monitor the flow fluctuation in the test section of the wind tunnel. Thereafter, a combined modal analysis is applied for the disturbance qualification. Additionally, the transient Mach number in the test section is measured. The disturbance qualification indicates that the multi-layer mesh performs well in providing reduction of vorticity reduction and acoustic fluctuations. Comparable flow quality of the freestream was also obtained using a combination of flexible damping materials. However, the life-span of the new damping materials is much longer. The time transient of the Mach number measured in the test section indicates that the mean flow is rather constant over run time. Furthermore, the time-averaged pressure along the settling chamber is recorded and it shows the distribution of pressure drop by settling chamber inserts.

  14. Fast, high temperature and thermolabile GC--MS in supersonic molecular beams

    Science.gov (United States)

    Dagan, Shai; Amirav, Aviv

    1994-05-01

    This work describes and evaluates the coupling of a fast gas chromatograph (GC) based on a short column and high carrier gas flow rate to a supersonic molecular beam mass spectrometer (MS). A 50 cm long megabore column serves for fast GC separation and connects the injector to the supersonic nozzle source. Sampling is achieved with a conventional syringe based splitless sample injection. The injector contains no septum and is open to the atmosphere. The linear velocity of the carrier gas is controlled by a by-pass (make-up) gas flow introduced after the column and prior to the supersonic nozzle. The supersonic expansion serves as a jet separator and the skimmed supersonic molecular beam (SMB) is highly enriched with the heavier organic molecules. The supersonic molecular beam constituents are ionized either by electron impact (EI) or hyperthermal surface ionization (HSI) and mass analyzed. A 1 s fast GC--MS of four aromatic molecules in methanol is demonstrated and some fundamental aspects of fast GC--MS with time limit constraints are outlined. The flow control (programming) of the speed of analysis is shown and the analysis of thermolabile and relatively non-volatile molecules is demonstrated and discussed. The tail-free, fast GC--MS of several mixtures is shown and peak tailing of caffeine is compared with that of conventional GC--MS. The improvement of the peak shapes with the SMB--MS is analyzed with the respect to the elimination of thermal vacuum chamber background. The extrapolated minimum detected amount was about 400 ag of anthracence-d10, with an elution time which was shorter than 2s. Repetitive injections could be performed within less than 10 s. The fast GC--MS in SMB seems to be ideal for fast target compound analysis even in real world, complex mixtures. The few seconds GC--MS separation and quantification of lead (as tetraethyllead) in gasoline, caffeine in coffee, and codeine in a drug is demonstrated. Controlled HSI selectivity is demonstrated in

  15. Effect of Seeding Particles on the Shock Structure of a Supersonic Jet

    Science.gov (United States)

    Porta, David; Echeverría, Carlos; Stern, Catalina

    2012-11-01

    The original goal of our work was to measure. With PIV, the velocity field of a supersonic flow produced by the discharge of air through a 4mm cylindrical nozzle. The results were superposed to a shadowgraph and combined with previous density measurements made with a Rayleigh scattering technique. The idea was to see if there were any changes in the flow field, close to the high density areas near the shocks. Shadowgraphs were made with and without seeding particles, (spheres of titanium dioxide). Surprisingly, it was observed that the flow structure with particles was shifted in the direction opposite to the flow with respect to the flow structure obtained without seeds. This result might contradict the belief that the seeding particles do not affect the flow and that the speed of the seeds correspond to the local speed of the flow. We acknowledge support from DGAPA UNAM through project IN117712 and from Facultad de Ciencias UNAM.

  16. Observations on the non-mixed length and unsteady shock motion in a two dimensional supersonic ejector

    Science.gov (United States)

    Rao, Srisha M. V.; Jagadeesh, Gopalan

    2014-03-01

    Key features that drive the operation of a supersonic ejector are the complex gasdynamic interactions of the primary and secondary flows within a variable area duct and the phenomenon of compressible turbulent mixing between them, which have to be understood at a fundamental level. An experimental study has been carried out on the mixing characteristics of a two dimensional supersonic ejector with a supersonic primary flow (air) of Mach number 2.48 and the secondary flow (subsonic) which is induced from the ambient. The non-mixed length, which is the length within the ejector for which the primary and secondary flow remain visually distinct is used to characterize the mixing in the ejector. The operating pressures, flow rates and wall static pressures along the ejector have been measured. Two flow visualization tools have been implemented—time resolved schlieren and laser scattering flow visualization. An important contribution has been the development of in-house image processing algorithms on the MATLAB platform to detect the non-mixed length from the schlieren and laser scattering images. The ratio of mass flow rates of the secondary flow to primary flow (entrainment ratio) has been varied in a range of 0.15-0.69 for two locations of the primary nozzle in the ejector duct. Representative cases have been computed using commercial CFD tool (Fluent) to supplement the experiments. Significant outcomes of the study are—the non-mixed length quantified from the flow visualization images is observed to lie within 4.5 to 5.2 times the height of the mixing duct which is confirmed by the wall static pressure profiles. The flow through the supersonic ejector in the mixed regime is explained using corroborative evidences from different diagnostic tools. A reduction of the non-mixed length by 46.7% is observed at operating conditions when the nozzle is sufficiently overexpanded. The disturbance caused to the mixing layer due to unsteady shock-boundary layer interactions

  17. Theoretical investigation of chemical and physical properties of gaseous fuels

    Energy Technology Data Exchange (ETDEWEB)

    Hermann, Fredrik

    1999-12-01

    This thesis is discussing the chemical and physical properties of different gaseous fuels. A mapping of about seventy gaseous fuels resulted in eleven type gases, these gases have mainly five components (inerts, H{sub 2}, CO, CH{sub 4} and higher order of hydrocarbons) of different quantities. Calculations of heating value and Wobbe number have been done. Dew point temperatures have been estimated by using three different programs. Flammability limits, laminar flame speed and auto ignition temperatures have been calculated by using a kinetic and chemical program developed by Mauss. Flammability limits have been compared with Le Chatelier's law and measurements. Problems related to combustion such as flash back, lift off and instability are closely connected with flame speed and flow patterns. These problems are discussed in terms of laminar flame speed and Reynolds' number. The main results of this study were: Auto ignition temperature for gas mixtures behavior is very complex and unpredictable. In general small quantities of hydrogen decrease the temperature of auto ignition. The calculations of flammability limits by the kinetic and chemical software showed good agreement to measurements. Low Btu gases requires large flow area in order to avoid large pressure drop.

  18. Gridless, very low energy, high-current, gaseous ion source

    Energy Technology Data Exchange (ETDEWEB)

    Vizir, A. V.; Oks, E. M. [High Current Electronics Institute, Russian Academy of Sciences, Tomsk 634055 (Russian Federation); State University of Control Systems and Radioelectronics, Tomsk 634050 (Russian Federation); Shandrikov, M. V.; Yushkov, G. Yu. [High Current Electronics Institute, Russian Academy of Sciences, Tomsk 634055 (Russian Federation)

    2010-02-15

    We have made and tested a very low energy gaseous ion source in which the plasma is established by a gaseous discharge with electron injection in an axially diverging magnetic field. A constricted arc with hidden cathode spot is used as the electron emitter (first stage of the discharge). The electron flux so formed is filtered by a judiciously shaped electrode to remove macroparticles (cathode debris from the cathode spot) from the cathode material as well as atoms and ions. The anode of the emitter discharge is a mesh, which also serves as cathode of the second stage of the discharge, providing a high electron current that is injected into the magnetic field region where the operating gas is efficiently ionized. In this discharge configuration, an electric field is formed in the ion generation region, accelerating gas ions to energy of several eV in a direction away from the source, without the use of a gridded acceleration system. Our measurements indicate that an argon ion beam is formed with an energy of several eV and current up to 2.5 A. The discharge voltage is kept at less than 20 V, to keep below ion sputtering threshold for cathode material, a feature which along with filtering of the injected electron flow, results in extremely low contamination of the generated ion flow.

  19. Computation of laminar heat transfer from gaseous plasmas in electromagnetic fields

    Science.gov (United States)

    Bose, T. K.

    1972-01-01

    Heat transfer analysis procedure is presented for two-temperature gaseous plasma. Analysis is based on laminar flow of singly-ionized, quasineutral plasma with variable properties. Sheath analysis is described for species in accelerating field, decelerating field, emitted from wall, and recombining at wall.

  20. Computational Investigation of Swirling Supersonic Jets Generated Through a Nozzle-Twisted Lance

    Science.gov (United States)

    Li, Mingming; Li, Qiang; Zou, Zongshu; An, Xizhong

    2017-02-01

    The dynamic characteristics of supersonic swirling jets generated through a nozzle-twisted lance are numerically studied. The essential features of the swirling jets are identified by defining a deviation angle. The effects of nozzle twist angle (NTA) on swirling flow intensity, coalescence characteristics, and dynamic parameter distributions of the jets are discussed. The rotational flow characteristics are revealed. The results show that the jets from the nozzle-twisted lance are imparted to a circumferential rotating movement around the lance axis, and such swirling flow is enhanced by increasing NTA. The enhanced swirling flow causes weaker coalescence of the jets, faster attenuations of the axial velocity, and higher heat transfer rate between the jets and surroundings. The supersonic core length, however, is found to be less sensitive to the swirling flow intensity. The radial spreading of the jets, changing non-monotonically with NTA, arrives at its maximum at 5 deg of NTA. Furthermore, the swirling flow induces a considerable tangential velocity component, and as a result, a holistic and effective horizontal swirling flow field develops. The y-vorticity distribution range and the corresponding magnitude turn larger with increasing NTA, which promote the vortex motion of the local fluid element and thus intensify the local mixing.

  1. Scaled Rocket Testing in Hypersonic Flow

    Science.gov (United States)

    Dufrene, Aaron; MacLean, Matthew; Carr, Zakary; Parker, Ron; Holden, Michael; Mehta, Manish

    2015-01-01

    NASA's Space Launch System (SLS) uses four clustered liquid rocket engines along with two solid rocket boosters. The interaction between all six rocket exhaust plumes will produce a complex and severe thermal environment in the base of the vehicle. This work focuses on a recent 2% scale, hot-fire SLS base heating test. These base heating tests are short-duration tests executed with chamber pressures near the full-scale values with gaseous hydrogen/oxygen engines and RSRMV analogous solid propellant motors. The LENS II shock tunnel/Ludwieg tube tunnel was used at or near flight duplicated conditions up to Mach 5. Model development was strongly based on the Space Shuttle base heating tests with several improvements including doubling of the maximum chamber pressures and duplication of freestream conditions. Detailed base heating results are outside of the scope of the current work, rather test methodology and techniques are presented along with broader applicability toward scaled rocket testing in supersonic and hypersonic flow.

  2. Supersonic Turbulent Boundary Layer: DNS and RANS

    Institute of Scientific and Technical Information of China (English)

    XU Jing-Lei; MA Hui-Yang

    2007-01-01

    We assess the performance of a few turbulence models for Reynolds averaged Navier-Stokes (RANS) simulation of supersonic boundary layers, compared to the direct numerical simulations (DNS) of supersonic flat-plate turbulent boundary layers, carried out by Gao et al. [Chin. Phys. Lett. 22 (2005) 1709] and Huang et al. [Sci.Chin. 48 (2005) 614], as well as some available experimental data. The assessment is made for two test cases, with incoming Mach numbers and Reynolds numbers M = 2.25, Re = 365, 000/in, and M = 4.5, Re - 1.7 × 107/m,respectively. It is found that in the first case the prediction of RANS models agrees well with the DNS and the experimental data, while for the second case the agreement of the DNS models with experiment is less satisfactory.The compressibility effect on the RANS models is discussed.

  3. Study of active cooling for supersonic transports

    Science.gov (United States)

    Brewer, G. D.; Morris, R. E.

    1975-01-01

    The potential benefits of using the fuel heat sink of hydrogen fueled supersonic transports for cooling large portions of the aircraft wing and fuselage are examined. The heat transfer would be accomplished by using an intermediate fluid such as an ethylene glycol-water solution. Some of the advantages of the system are: (1) reduced costs by using aluminum in place of titanium, (2) reduced cabin heat loads, and (3) more favorable environmental conditions for the aircraft systems. A liquid hydrogen fueled, Mach 2.7 supersonic transport aircraft design was used for the reference uncooled vehicle. The cooled aircraft designs were analyzed to determine their heat sink capability, the extent and location of feasible cooled surfaces, and the coolant passage size and spacing.

  4. Supersonic Motions of Galaxies in Clusters

    CERN Document Server

    Faltenbacher, A; Nagai, D; Gottlöber, S; Faltenbacher, Andreas; Kravtsov, Andrey V.; Nagai, Daisuke; Gottloeber, Stefan

    2004-01-01

    We study motions of galaxies in galaxy clusters formed in the concordance LCDM cosmology. We use high-resolution cosmological simulations that follow dynamics of dark matter and gas and include various physical processes critical for galaxy formation: gas cooling, heating and star formation. Analysing motions of galaxies and the properties of intracluster gas in the sample of eight simulated clusters at z=0, we study velocity dispersion profiles of the dark matter, gas, and galaxies. We measure the mean velocity of galaxy motions and gas sound speed as a function of radius and calculate the average Mach number of galaxy motions. The simulations show that galaxies, on average, move supersonically with the average Mach number of ~1.4, approximately independent of the cluster-centric radius. The supersonic motions of galaxies may potentially provide an important source of heating for the intracluster gas by driving weak shocks and via dynamical friction, although these heating processes appear to be inefficient ...

  5. Control of star formation by supersonic turbulence

    CERN Document Server

    MacLow, M M; Low, Mordecai-Mark Mac; Klessen, Ralf S.

    2004-01-01

    Understanding the formation of stars in galaxies is central to much of modern astrophysics. For several decades it has been thought that stellar birth is primarily controlled by the interplay between gravity and magnetostatic support, modulated by ambipolar diffusion. Recently, however, both observational and numerical work has begun to suggest that support by supersonic turbulence rather than magnetic fields controls star formation. In this review we outline a new theory of star formation relying on the control by turbulence. We demonstrate that although supersonic turbulence can provide global support, it nevertheless produces density enhancements that allow local collapse. Inefficient, isolated star formation is a hallmark of turbulent support, while efficient, clustered star formation occurs in its absence. The consequences of this theory are then explored for both local star formation and galactic scale star formation. (Abstract abbreviated)

  6. Conceptual Design of a Supersonic Jet Engine

    OpenAIRE

    Kareliusson, Joakim; Nordqvist, Melker

    2014-01-01

    This thesis is a response to the request for proposal issued by a joint collaboration between the AIAA Foundation and ASME/IGTI as a student competition to design a new turbofan engine intended for a conceptual supersonic business jet expected to enter service in 2025. Due to the increasing competition in the aircraft industry and the more stringent environmental legislations the new engine is expected to provide a lower fuel burn than the current engine intended for the aircraft to increase ...

  7. Research of low boom and low drag supersonic aircraft design

    OpenAIRE

    Feng Xiaoqiang; Li Zhanke; Song Bifeng

    2014-01-01

    Sonic boom reduction will be an issue of utmost importance in future supersonic transport, due to strong regulations on acoustic nuisance. The paper describes a new multi-objective optimization method for supersonic aircraft design. The method is developed by coupling Seebass–George–Darden (SGD) inverse design method and multi-objective genetic algorithm. Based on the method, different codes are developed. Using a computational architecture, a conceptual supersonic aircraft design environment...

  8. Supersonic and subsonic measurements of mesospheric ionization.

    Science.gov (United States)

    Hale, L. C.; Nickell, L. C.; Kennedy, B.; Powell, T. A.

    1972-01-01

    An Arcas rocket-parachute system was used at night to compare supersonic and subsonic ionization measurements below 75 km. A hemispherical nose-tip probe was used on ascent and a parachute-borne blunt probe on descent to measure polar conductivities, which were due entirely to positive and negative ions. The velocity of the supersonic probe was Mach 2.5 at 50 km and 1.75 at 70 km; the blunt probe was subsonic below 71 km. Between 65 and 75 km the ratio of negative to positive conductivities (and thus of mobilities) determined by the blunt probe was about 1.2, and it approached 1 below this altitude range. The ratio obtained by the nose-tip probe varied from 1.5 at 75 km to .6 at 65 km, thus indicating a rapid variation of the effects of the shock wave on the sampled ions. The absolute values of positive conductivity measured subsonically and supersonically were essentially identical from 60 to 75 km, indicating that the sampled ions were unchanged by the shock. However, below 60 km the shock apparently 'broke up' the positive ions, as indicated by higher measured conductivities.

  9. Supersonic Jet Excitation using Flapping Injection

    CERN Document Server

    Hafsteinsson, Haukur; Andersson, Niklas; Cuppoletti, Daniel; Gutmark, Ephraim; Prisell, Erik

    2013-01-01

    Supersonic jet noise reduction is important for high speed military aircraft. Lower acoustic levels would reduce structural fatigue leading to longer lifetime of the jet aircraft. It is not solely structural aspects which are of importance, health issues of the pilot and the airfield per- sonnel are also very important, as high acoustic levels may result in severe hearing damage. It remains a major challenge to reduce the overall noise levels of the aircraft, where the supersonic exhaust is the main noise source for near ground operation. Fluidic injection into the supersonic jet at the nozzle exhaust has been shown as a promising method for noise reduction. It has been shown to speed up the mix- ing process of the main jet, hence reducing the kinetic energy level of the jet and the power of the total acoustic radiation. Furthermore, the interaction mechanism between the fluidic injection and the shock structure in the jet exhaust plays a crucial role in the total noise radia- tion. In this study, LES is used...

  10. Supersonic Gas-Liquid Cleaning System

    Science.gov (United States)

    Kinney, Frank

    1996-01-01

    The Supersonic Gas-Liquid Cleaning System Research Project consisted mainly of a feasibility study, including theoretical and engineering analysis, of a proof-of-concept prototype of this particular cleaning system developed by NASA-KSC. The cleaning system utilizes gas-liquid supersonic nozzles to generate high impingement velocities at the surface of the device to be cleaned. The cleaning fluid being accelerated to these high velocities may consist of any solvent or liquid, including water. Compressed air or any inert gas is used to provide the conveying medium for the liquid, as well as substantially reduce the total amount of liquid needed to perform adequate surface cleaning and cleanliness verification. This type of aqueous cleaning system is considered to be an excellent way of conducting cleaning and cleanliness verification operations as replacements for the use of CFC 113 which must be discontinued by 1995. To utilize this particular cleaning system in various cleaning applications for both the Space Program and the commercial market, it is essential that the cleaning system, especially the supersonic nozzle, be characterized for such applications. This characterization consisted of performing theoretical and engineering analysis, identifying desirable modifications/extensions to the basic concept, evaluating effects of variations in operating parameters, and optimizing hardware design for specific applications.

  11. Experimental observations of a complex, supersonic nozzle concept

    Science.gov (United States)

    Magstadt, Andrew; Berry, Matthew; Glauser, Mark; Ruscher, Christopher; Gogineni, Sivaram; Kiel, Barry; Skytop Turbulence Labs, Syracuse University Team; Spectral Energies, LLC. Team; Air Force Research Laboratory Team

    2015-11-01

    A complex nozzle concept, which fuses multiple canonical flows together, has been experimentally investigated via pressure, schlieren and PIV in the anechoic chamber at Syracuse University. Motivated by future engine designs of high-performance aircraft, the rectangular, supersonic jet under investigation has a single plane of symmetry, an additional shear layer (referred to as a wall jet) and an aft deck representative of airframe integration. Operating near a Reynolds number of 3 ×106 , the nozzle architecture creates an intricate flow field comprised of high turbulence levels, shocks, shear & boundary layers, and powerful corner vortices. Current data suggest that the wall jet, which is an order of magnitude less energetic than the core, has significant control authority over the acoustic power through some non-linear process. As sound is a direct product of turbulence, experimental and analytical efforts further explore this interesting phenomenon associated with the turbulent flow. The authors acknowledge the funding source, a SBIR Phase II project with Spectral Energies, LLC. and AFRL turbine engine branch under the direction of Dr. Barry Kiel.

  12. Linear and Nonlinear Evolution of Disturbances in Supersonic Streamwise Vortices

    Science.gov (United States)

    Khorrami, Mehdi R.; Chang, Chau-Lyan; Wie, Yong-Sun

    1997-11-01

    Effective control of compressible streamwise vortices play a significant role in both external and internal aerodynamics. In this study, evolution of disturbances in a supersonic vortex is studied by using quasi-cylindrical linear stability analysis and parabolized stability equations (PSE)footnote M. R. Malik and C.-L. Chang, AIAA Paper 97-0758. formulation. Appropriate mean-flow profilesfootnote M. K. Smart, I. M. Kalkhoran, and J. Bentson, AIAA Paper 94-2576. suitable for stability analysis were identified and modeled successfully. Using linear stability analysis, the stability characteristics of axisymmetric vortices were mapped thoroughly. The results indicate that viscosity has very little effect while increasing Mach number significantly stabilizes the disturbance. Linear PSE analysis shows that the effect of streamwise mean flow variation is small for the case considered here. Nonlinear evolution of helical modes is also studied by using PSE. The growth of the disturbances results in the appearance of coherent large scale motion and significant mean flow distortion in the axial velocity and temperature fields. In the end, nonlinear effects tend to stabilize the vortex.

  13. Aerodynamics characteristic of axisymmetric surface protuberance in supersonic regime

    KAUST Repository

    Qamar, Adnan

    2012-01-01

    The present work deals with the problem of an axi-symmetric surface protuberance mounted on a spherical nosed body of revolution. The numerical computations are carried out for laminar supersonic viscous flow for trapezoidal shape axi-symmetric protuberances. A free stream Mach number ranging from 3 to 8 in steps of 1 at a fixed free stream Reynolds number of 1.8x10(4) has been used in the present study. The steady solutions are obtained using a time marching approach. A newly developed Particle Velocity Upwinding (PVU) scheme has been used for the computation. The spatial flow pattern exhibits a strong bow shock in front of the hemispherical nose, which engulfs the entire base body. Near the protuberance, the fluid particle decelerates due to the adverse pressure created by the protuberance and thus the flow separates in front of the protuberance. This point of separation is found to be a function of Mach number and the protuberance shape. A low-pressure expansion region dominates the base region of the obstacle. The reattachment point for the base separation is also a function of Mach number. As the Mach number is increased the reattachment point shifts toward the protuberances base. A weak recompression shock is also seen in the base, which affects the separated zone behind the protuberance. The important design parameters such as skin friction, heat transfer, drag, and surface pressure coefficients are reported extensively.

  14. Aerodynamic Design and Numerical Analysis of Supersonic Turbine for Turbo Pump

    Science.gov (United States)

    Fu, Chao; Zou, Zhengping; Kong, Qingguo; Cheng, Honggui; Zhang, Weihao

    2016-09-01

    Supersonic turbine is widely used in the turbo pump of modern rocket. A preliminary design method for supersonic turbine has been developed considering the coupling effects of turbine and nozzle. Numerical simulation has been proceeded to validate the feasibility of the design method. As the strong shockwave reflected on the mixing plane, additional numerical simulated error would be produced by the mixing plane model in the steady CFD. So unsteady CFD is employed to investigate the aerodynamic performance of the turbine and flow field in passage. Results showed that the preliminary design method developed in this paper is suitable for designing supersonic turbine. This periodical variation of complex shockwave system influences the development of secondary flow, wake and shock-boundary layer interaction, which obviously affect the secondary loss in vane passage. The periodical variation also influences the strength of reflecting shockwave, which affects the profile loss in vane passage. Besides, high circumferential velocity at vane outlet and short blade lead to high radial pressure gradient, which makes the low kinetic energy fluid moves towards hub region and produces additional loss.

  15. Vortex Generators in a Streamline-Traced, External-Compression Supersonic Inlet

    Science.gov (United States)

    Baydar, Ezgihan; Lu, Frank K.; Slater, John W.; Trefny, Charles J.

    2017-01-01

    Vortex generators within a streamline-traced, external-compression supersonic inlet for Mach 1.66 were investigated to determine their ability to increase total pressure recovery and reduce total pressure distortion. The vortex generators studied were rectangular vanes arranged in counter-rotating and co-rotating arrays. The vane geometric factors of interest included height, length, spacing, angle-of-incidence, and positions upstream and downstream of the inlet terminal shock. The flow through the inlet was simulated numerically through the solution of the steady-state, Reynolds-averaged Navier-Stokes equations on multi-block, structured grids using the Wind-US flow solver. The vanes were simulated using a vortex generator model. The inlet performance was characterized by the inlet total pressure recovery and the radial and circumferential total pressure distortion indices at the engine face. Design of experiments and statistical analysis methods were applied to quantify the effect of the geometric factors of the vanes and search for optimal vane arrays. Co-rotating vane arrays with negative angles-of-incidence positioned on the supersonic diffuser were effective in sweeping low-momentum flow from the top toward the sides of the subsonic diffuser. This distributed the low-momentum flow more evenly about the circumference of the subsonic diffuser and reduced distortion. Co-rotating vane arrays with negative angles-of-incidence or counter-rotating vane arrays positioned downstream of the terminal shock were effective in mixing higher-momentum flow with lower-momentum flow to increase recovery and decrease distortion. A strategy of combining a co-rotating vane array on the supersonic diffuser with a counter-rotating vane array on the subsonic diffuser was effective in increasing recovery and reducing distortion.

  16. An Automated DAKOTA and VULCAN-CFD Framework with Application to Supersonic Facility Nozzle Flowpath Optimization

    Science.gov (United States)

    Axdahl, Erik L.

    2015-01-01

    Removing human interaction from design processes by using automation may lead to gains in both productivity and design precision. This memorandum describes efforts to incorporate high fidelity numerical analysis tools into an automated framework and applying that framework to applications of practical interest. The purpose of this effort was to integrate VULCAN-CFD into an automated, DAKOTA-enabled framework with a proof-of-concept application being the optimization of supersonic test facility nozzles. It was shown that the optimization framework could be deployed on a high performance computing cluster with the flow of information handled effectively to guide the optimization process. Furthermore, the application of the framework to supersonic test facility nozzle flowpath design and optimization was demonstrated using multiple optimization algorithms.

  17. Computing supersonic non-premixed turbulent combustion by an SMLD flamelet progress variable model

    CERN Document Server

    Coclite, A; Gurtner, M; De Palma, P; Haidnd, O J; Pascazio, G

    2015-01-01

    This paper describes the numerical simulation of the NASA Langley Research Center supersonic H2 -Air combustion chamber performed using two approaches to model the presumed probability density function (PDF) in the flamelet progress variable (FPV) framework. The first one is a standard FPV model, built presuming the functional shape of the PDFs of the mixture fraction, Z, and of the progress parameter, {\\Lambda}. In order to enhance the prediction capabilities of such a model in high-speed reacting flows, a second approach is proposed employing the statistically most likely distribution (SMLD) techcnique to presume the joint PDF of Z and {\\Lambda}, without any assumption about their behaviour. The standard and FPV-SMLD models have been developed using the low Mach number assumption. In both cases, the temperature is evaluated by solving the total-energy conservation equation, providing a more suitable approach for the simulation of supersonic combustion. By comparison with experimental data, the proposed SMLD...

  18. The Density Variance--Mach Number Relation in Supersonic Turbulence: I. Isothermal, magnetised gas

    CERN Document Server

    Molina, F Z; Federrath, C; Klessen, R S

    2012-01-01

    It is widely accepted that supersonic, magnetised turbulence plays a fundamental role for star formation in molecular clouds. It produces the initial dense gas seeds out of which new stars can form. However, the exact relation between gas compression, turbulent Mach number, and magnetic field strength is still poorly understood. Here, we introduce and test an analytical prediction for the relation between the density variance and the root-mean-square Mach number in supersonic, isothermal, magnetised turbulent flows. We approximate the density and velocity structure of the interstellar medium as a superposition of shock waves. We obtain the density contrast considering the momentum continuity equation for a single magnetised shock and extrapolate this result to the entire cloud. Depending on the field geometry, we then make three different assumptions based on observational and theoretical constraints: B independent of density, B proportional to the root square of the density and B proportional to the density....

  19. The Effect of Magnetohydrodynamic (MHD) Energy Bypass on Specific Thrust for a Supersonic Turbojet Engine

    Science.gov (United States)

    Benyo, Theresa L.

    2010-01-01

    This paper describes the preliminary results of a thermodynamic cycle analysis of a supersonic turbojet engine with a magnetohydrodynamic (MHD) energy bypass system that explores a wide range of MHD enthalpy extraction parameters. Through the analysis described here, it is shown that applying a magnetic field to a flow path in the Mach 2.0 to 3.5 range can increase the specific thrust of the turbojet engine up to as much as 420 N/(kg/s) provided that the magnitude of the magnetic field is in the range of 1 to 5 Tesla. The MHD energy bypass can also increase the operating Mach number range for a supersonic turbojet engine into the hypersonic flight regime. In this case, the Mach number range is shown to be extended to Mach 7.0.

  20. Gaseous Electronics Tables, Atoms, and Molecules

    CERN Document Server

    Raju, Gorur Govinda

    2011-01-01

    With the constant emergence of new research and application possibilities, gaseous electronics is more important than ever in disciplines including engineering (electrical, power, mechanical, electronics, and environmental), physics, and electronics. The first resource of its kind, Gaseous Electronics: Tables, Atoms, and Molecules fulfills the author's vision of a stand-alone reference to condense 100 years of research on electron-neutral collision data into one easily searchable volume. It presents most--if not all--of the properly classified experimental results that scientists, researchers,

  1. Gaseous hydrogen embrittlement of high strength steels

    Science.gov (United States)

    Gangloff, R. P.; Wei, R. P.

    1977-01-01

    The effects of temperature, hydrogen pressure, stress intensity, and yield strength on the kinetics of gaseous hydrogen assisted crack propagation in 18Ni maraging steels were investigated experimentally. It was found that crack growth rate as a function of stress intensity was characterized by an apparent threshold for crack growth, a stage where the growth rate increased sharply, and a stage where the growth rate was unchanged over a significant range of stress intensity. Cracking proceeded on load application with little or no detectable incubation period. Gaseous hydrogen embrittlement susceptibility increased with increasing yield strength.

  2. Transonic and Low-Supersonic Aeroelastic Analysis of a Two-Degree Airfoil with a Freeplay Non-Linearity

    Science.gov (United States)

    KIM, DONG-HYUN; LEE, IN

    2000-07-01

    A two-degree-of-freedom airfoil with a freeplay non-linearity in the pitch and plunge directions has been analyzed in the transonic and low-supersonic flow region, where aerodynamic non-linearities also exist. The primary purpose of this study is to show aeroelastic characteristics due to freeplay structural non-linearity in the transonic and low-supersonic regions. The unsteady aerodynamic forces on the airfoil were evaluated using two-dimensional unsteady Euler code, and the resulting aeroelastic equations are numerically integrated to obtain the aeroelastic time responses of the airfoil motions and to investigate the dynamic instability. The present model has been considered as a simple aeroelastic model, which is equivalent to the folding fin of an advanced generic missile. From the results of the present study, characteristics of important vibration responses and aeroelastic instabilities can be observed in the transonic and supersonic regions, especially considering the effect of structural non-linearity in the pitch and plunge directions. The regions of limit-cycle oscillation are shown at much lower velocities, especially in the supersonic flow region, than the divergent flutter velocities of the linear structure model. It is also shown that even small freeplay angles can lead to severe dynamic instabilities and dangerous fatigue conditions for the flight vehicle wings and control fins.

  3. Linear models for sound from supersonic reacting mixing layers

    Science.gov (United States)

    Chary, P. Shivakanth; Samanta, Arnab

    2016-12-01

    We perform a linearized reduced-order modeling of the aeroacoustic sound sources in supersonic reacting mixing layers to explore their sensitivities to some of the flow parameters in radiating sound. Specifically, we investigate the role of outer modes as the effective flow compressibility is raised, when some of these are expected to dominate over the traditional Kelvin-Helmholtz (K-H) -type central mode. Although the outer modes are known to be of lesser importance in the near-field mixing, how these radiate to the far-field is uncertain, on which we focus. On keeping the flow compressibility fixed, the outer modes are realized via biasing the respective mean densities of the fast (oxidizer) or slow (fuel) side. Here the mean flows are laminar solutions of two-dimensional compressible boundary layers with an imposed composite (turbulent) spreading rate, which we show to significantly alter the growth of instability waves by saturating them earlier, similar to in nonlinear calculations, achieved here via solving the linear parabolized stability equations. As the flow parameters are varied, instability of the slow modes is shown to be more sensitive to heat release, potentially exceeding equivalent central modes, as these modes yield relatively compact sound sources with lesser spreading of the mixing layer, when compared to the corresponding fast modes. In contrast, the radiated sound seems to be relatively unaffected when the mixture equivalence ratio is varied, except for a lean mixture which is shown to yield a pronounced effect on the slow mode radiation by reducing its modal growth.

  4. PIV Measurements of Supersonic Internally-Mixed Dual-Stream Jets

    Science.gov (United States)

    Bridges, James E.; Wernet, Mark P.

    2012-01-01

    While externally mixed, or separate flow, nozzle systems are most common in high bypass-ratio aircraft, they are not as attractive for use in lower bypass-ratio systems and on aircraft that will fly supersonically. The noise of such propulsion systems is also dominated by jet noise, making the study and noise reduction of these exhaust systems very important, both for military aircraft and future civilian supersonic aircraft. This paper presents particle image velocimetry of internally mixed nozzle with different area ratios between core and bypass, and nozzles that are ideally expanded and convergent. Such configurations independently control the geometry of the internal mixing layer and of the external shock structure. These allow exploration of the impact of shocks on the turbulent mixing layers, the impact of bypass ratio on broadband shock noise and mixing noise, and the impact of temperature on the turbulent flow field. At the 2009 AIAA/CEAS Aeroacoustics Conference the authors presented data and analysis from a series of tests that looked at the acoustics of supersonic jets from internally mixed nozzles. In that paper the broadband shock and mixing noise components of the jet noise were independently manipulated by holding Mach number constant while varying bypass ratio and jet temperature. Significant portions of that analysis was predicated on assumptions regarding the flow fields of these jets, both shock structure and turbulence. In this paper we add to that analysis by presenting particle image velocimetry measurements of the flow fields of many of those jets. In addition, the turbulent velocity data documented here will be very useful for validation of computational flow codes that are being developed to design advanced nozzles for future aircraft.

  5. Evolution of supersonic corner vortex in a hypersonic inlet/isolator model

    Science.gov (United States)

    Huang, He-Xia; Tan, Hui-Jun; Sun, Shu; Ling, Yu

    2016-12-01

    There are complex corner vortex flows in a rectangular hypersonic inlet/isolator. The corner vortex propagates downstream and interacts with the shocks and expansion waves in the isolator repeatedly. The supersonic corner vortex in a generic hypersonic inlet/isolator model is theoretically and numerically analyzed at a freestream Mach number of 4.92. The cross-flow topology of the corner vortex flow is found to obey Zhang's theory ["Analytical analysis of subsonic and supersonic vortex formation," Acta Aerodyn. Sin. 13, 259-264 (1995)] strictly, except for the short process with the vortex core situated in a subsonic flow which is surrounded by a supersonic flow. In general, the evolution history of the corner vortex under the influence of the background waves in the hypersonic inlet/isolator model can be classified into two types, namely, from the adverse pressure gradient region to the favorable pressure gradient region and the reversed one. For type 1, the corner vortex is a one-celled vortex with the cross-sectional streamlines spiraling inwards at first. Then the Hopf bifurcation occurs and the streamlines in the outer part of the limit cycle switch to spiraling outwards, yielding a two-celled vortex. The limit cycle shrinks gradually and finally vanishes with the streamlines of the entire corner vortex spiraling outwards. For type 2, the cross-sectional streamlines of the corner vortex spiral outwards first. Then a stable limit cycle is formed, yielding a two-celled vortex. The short-lived limit cycle forces the streamlines in the corner vortex to change the spiraling trends rapidly. Although it is found in this paper that there are some defects on the theoretical proof of the limit cycle, Zhang's theory is proven useful for the prediction and qualitative analysis of the complex corner vortex in a hypersonic inlet/isolator. In addition, three conservation laws inside the limit cycle are obtained.

  6. Gaseous haloes : Linking galaxies to the IGM

    NARCIS (Netherlands)

    Fraternali, Filippo; Binney, James; Oosterloo, Tom; Sancisi, Renzo

    2007-01-01

    In recent years, evidence has accumulated that nearby spiral galaxies are surrounded by massive haloes of neutral and ionised gas. These gaseous haloes rotate more slowly than the disks and show inflow motions. They are clearly analogous to the High Velocity Clouds of the Milky Way. We show that the

  7. Low Density Supersonic Decelerator (LDSD) Supersonic Flight Dynamics Test (SFDT) Plume Induced Environment Modelling

    Science.gov (United States)

    Mobley, B. L.; Smith, S. D.; Van Norman, J. W.; Muppidi, S.; Clark, I

    2016-01-01

    Provide plume induced heating (radiation & convection) predictions in support of the LDSD thermal design (pre-flight SFDT-1) Predict plume induced aerodynamics in support of flight dynamics, to achieve targeted freestream conditions to test supersonic deceleration technologies (post-flight SFDT-1, pre-flight SFDT-2)

  8. Methane Recovery from Gaseous Mixtures Using Carbonaceous Adsorbents

    Science.gov (United States)

    Buczek, Bronisław

    2016-06-01

    Methane recovery from gaseous mixtures has both economical and ecological aspect. Methane from different waste gases like mine gases, nitrogenated natural gases and biogases can be treated as local source for production electric and heat energy. Also occurs the problem of atmosphere pollution with methane that shows over 20 times more harmful environmental effect in comparison to carbon dioxide. One of the ways utilisation such gases is enrichment of methane in the PSA technique, which requires appropriate adsorbents. Active carbons and carbon molecular sieve produced by industry and obtained in laboratory scale were examined as adsorbent for methane recuperation. Porous structure of adsorbents was investigated using densimetry measurements and adsorption of argon at 77.5K. On the basis of adsorption data, the Dubinin-Radushkevich equation parameters, micropore volume (Wo) and characteristics of energy adsorption (Eo) as well as area micropores (Smi) and BET area (SBET) were determined. The usability of adsorbents in enrichment of the methane was evaluated in the test, which simulate the basic stages of PSA process: a) adsorbent degassing, b) pressure raise in column by feed gas, c) cocurrent desorption with analysis of out flowing gas. The composition of gas phase was accepted as the criterion of the suitability of adsorbent for methane separation from gaseous mixtures. The relationship between methane recovery from gas mixture and texture parameters of adsorbents was found.

  9. CFD Analysis of Supersonic Coaxial Jets on Effect of Spreading Rates

    Directory of Open Access Journals (Sweden)

    K. Kathiresan

    2014-04-01

    Full Text Available Prevailing high-speed air-breathing propulsion systems invariably banks on coaxial jets which plays a vigorous role in stabilization of flames and combustion emission. Coaxial jets have applications in supersonic ejectors, noise control techniques and enhancement of mixing. Coaxial jet nozzles regulate spreading rates by developing virtuous mean flow and shortening primary flow potential core length. In the present paper, two-dimensional coaxial jet profiles of different area ratios are designed and analyzed. The models were designed in ANSYS Design Modeler and the numerical simulation was done in ANSYS FLUENT 14.5 using the two dimensional density based energy equation and k- ε turbulence model with primary supersonic flow and secondary subsonic flow. The contours of turbulence intensity, acoustics power level and axial-velocity are investigated along the flow direction. This study shows that increasing the area ratio results in less turbulence which in turn increases the potential core length,acoustics power level, turbulent kinetic energy and generates more noise.

  10. Effect of Homogeneous Condensation on the Interaction of Supersonic Moist Air Jets with Resonance Tube

    Directory of Open Access Journals (Sweden)

    M.M Ashraful.Alam

    2013-01-01

    Full Text Available The Hartmann tube, can use for flow-control, is a device which generates high intensity sound through the shock wave oscillations, are created by the interaction of the supersonic jet. In this study, two-phase flow simulations are carried out to characterize the effect of non-equilibrium condensation on the unsteady flowfield of the Hartmann resonance tube. This present numerical work provides a new insight on the flow dynamics and acoustics of the resonance tube – including the shock nature, the tube gas heating, and the effect of non-equilibrium condensation on the flow structure. A TVD numerical method is applied to the Reynolds and Favre-averaged Navier-Stokes equations, and droplet growth equation of liquid phase production. The simulations are performed over a range of nozzle pressure ratios. The numerically simulated flow structure of under-expanded supersonic jets is compared with experimental data. Moreover, the predicted frequency of end wall pressure fluctuations is compared with the experimental results.

  11. High speed titanium coating by Supersonic Laser Deposition

    OpenAIRE

    LUPOI, ROCCO

    2011-01-01

    PUBLISHED The importance of metal coating technologies drives the continuous improvement of metal deposition techniques for application in a wide range of industrial sectors. This work presents the foundations of a new process technology f or the deposition of t itanium coatings on steel tube substrates using supersonic powder streams and impact site laser heating , known as Supersonic Laser Deposition (SLD). M et...

  12. Effects of the jet-to-crossflow momentum ratio on a sonic jet into a supersonic crossflow

    Institute of Scientific and Technical Information of China (English)

    2011-01-01

    Numerical investigation of a transverse sonic jet injected into a supersonic crossflow was carried out using large-eddy simulation for a free-stream Mach number M = 1.6 and a Reynolds number Re = 1.38×10~5 based on the jet diameter.Effects of the jet-to-crossflow momentum ratio on various fundamental mechanisms dictating the intricate flow phenomena,including flow structures, turbulent characters and frequency behaviors,have been studied.The complex flow structures and the relevant flow features are disc...

  13. Advanced Noise Abatement Procedures for a Supersonic Business Jet

    Science.gov (United States)

    Berton, Jeffrey J.; Jones, Scott M.; Seidel, Jonathan A.; Huff, Dennis L.

    2017-01-01

    Supersonic civil aircraft present a unique noise certification challenge. High specific thrust required for supersonic cruise results in high engine exhaust velocity and high levels of jet noise during takeoff. Aerodynamics of thin, low-aspect-ratio wings equipped with relatively simple flap systems deepen the challenge. Advanced noise abatement procedures have been proposed for supersonic aircraft. These procedures promise to reduce airport noise, but they may require departures from normal reference procedures defined in noise regulations. The subject of this report is a takeoff performance and noise assessment of a notional supersonic business jet. Analytical models of an airframe and a supersonic engine derived from a contemporary subsonic turbofan core are developed. These models are used to predict takeoff trajectories and noise. Results indicate advanced noise abatement takeoff procedures are helpful in reducing noise along lateral sidelines.

  14. Characterization of the supersonic wake of a generic space launcher

    Science.gov (United States)

    Schreyer, A.-M.; Stephan, S.; Radespiel, R.

    2017-03-01

    The wake flow of a generic axisymmetric space-launcher model is investigated experimentally for flow cases with and without propulsive jet to gain insight into the wake-flow phenomena at a supersonic stage of the flight trajectory which is especially critical with respect to dynamic loads on the structure. Measurements are performed at Mach 2.9 and a Reynolds number Re D = 1.3 × 106 based on model diameter D. The nozzle exit velocity of the jet is at Mach 2.5, and the flow is moderately underexpanded ( p e/ p ∞ = 5.7). The flow topology is described based on velocity measurements in the wake by means of particle image velocimetry and schlieren visualizations. Mean and fluctuating mass-flux profiles are obtained from hot-wire measurements, and unsteady wall-pressure measurements on the main-body base are performed simultaneously. This way, the evolution of the wake flow and its spectral content can be observed along with the footprint of this highly dynamic flow on the launcher main-body base. For the case without propulsive jet, a large separated zone is forming downstream of the main body shoulder, and the flow is reattaching further downstream on the afterbody. The afterexpanding propulsive jet (air) causes a displacement of the shear layer away from the wall, preventing the reattachment of the flow. In the spectral analysis of the baseline case, a dominant frequency around St D = 0.25 is found in the pressure-fluctuation signal at the main-body base of the launcher. This frequency is related to the shedding of the separation bubble and is less pronounced in the presence of the propulsive jet. In the shear layer itself, the spectra obtained from the hot-wire signal have a more broadband low-frequency content, which also reflects the characteristic frequency of turbulent structures convected in the shear layer, a swinging motion ( St D = 0.6), as well as the radial flapping motion of the shear layer ( St D = 0.85), respectively. Moving downstream along the

  15. Low temperature gaseous nitriding and carburising of stainless steel

    DEFF Research Database (Denmark)

    Christiansen, Thomas; Somers, Marcel A.J.

    2005-01-01

    The response of various austenitic and duplex stainless steel grades to low temperature gaseous nitriding and carburising was investigated. Gaseous nitriding was performed in ammonia/hydrogen mixtures at temperatures ,723 K; gaseous carburising was carried out in carbon monoxide/hydrogen mixtures...

  16. Characteristics of laser supersonic heating method for producing micro metallic particles

    Science.gov (United States)

    Lin, Shih-Lung; Lin, Jehnming

    2005-10-01

    In this article, the authors analyzed the process characteristics of laser supersonic heating method for producing metallic particles and predicted the in-flight tracks and shapes of micro-particles. A pulse Nd-YAG laser was used to heat the carbon steel target placed within an air nozzle. The high-pressure air with supersonic velocity was used to carry out carbon steel particles in the nozzle. The shock wave structures at the nozzle exit were visualized by the shadowgraph method. The carbon steel particles produced by laser supersonic heating method were grabbed and the spraying angles of the particle tracks were visualized. The velocity of the in-flight particles was measured by a photodiode sensor and compared with the numerical result. The solidification of carbon steel particles with diameters of 1-50 μm in compressible flow fields were investigated. The result shows that there is no significant difference in the dimension of solid carbon steel particles produced at shock wave fields under various entrance pressures (3-7 bar) with a constant laser energy radiation.

  17. Underexpanded Supersonic Plume Surface Interactions: Applications for Spacecraft Landings on Planetary Bodies

    Science.gov (United States)

    Mehta, M.; Sengupta, A.; Renno, N. O.; Norman, J. W.; Gulick, D. S.

    2011-01-01

    Numerical and experimental investigations of both far-field and near-field supersonic steady jet interactions with a flat surface at various atmospheric pressures are presented in this paper. These studies were done in assessing the landing hazards of both the NASA Mars Science Laboratory and Phoenix Mars spacecrafts. Temporal and spatial ground pressure measurements in conjunction with numerical solutions at altitudes of approx.35 nozzle exit diameters and jet expansion ratios (e) between 0.02 and 100 are used. Data from steady nitrogen jets are compared to both pulsed jets and rocket exhaust plumes at Mach approx.5. Due to engine cycling, overpressures and the plate shock dynamics are different between pulsed and steady supersonic impinging jets. In contrast to highly over-expanded (e plumes, results show that there is a relative ground pressure load maximum for moderately underexpanded (e approx.2-5) jets which demonstrate a long collimated plume shock structure. For plumes with e much >5 (lunar atmospheric regime), the ground pressure is minimal due to the development of a highly expansive shock structure. We show this is dependent on the stability of the plate shock, the length of the supersonic core and plume decay due to shear layer instability which are all a function of the jet expansion ratio. Asymmetry and large gradients in the spatial ground pressure profile and large transient overpressures are predominantly linked to the dynamics of the plate shock. More importantly, this study shows that thruster plumes exhausting into martian environments possess the largest surface pressure loads and can occur at high spacecraft altitudes in contrast to the jet interactions at terrestrial and lunar atmospheres. Theoretical and analytical results also show that subscale supersonic cold gas jets adequately simulate the flow field and loads due to rocket plume impingement provided important scaling parameters are in agreement. These studies indicate the critical

  18. Quantitative Thermochemical Measurements in High-Pressure Gaseous Combustion

    Science.gov (United States)

    Kojima, Jun J.; Fischer, David G.

    2012-01-01

    We present our strategic experiment and thermochemical analyses on combustion flow using a subframe burst gating (SBG) Raman spectroscopy. This unconventional laser diagnostic technique has promising ability to enhance accuracy of the quantitative scalar measurements in a point-wise single-shot fashion. In the presentation, we briefly describe an experimental methodology that generates transferable calibration standard for the routine implementation of the diagnostics in hydrocarbon flames. The diagnostic technology was applied to simultaneous measurements of temperature and chemical species in a swirl-stabilized turbulent flame with gaseous methane fuel at elevated pressure (17 atm). Statistical analyses of the space-/time-resolved thermochemical data provide insights into the nature of the mixing process and it impact on the subsequent combustion process in the model combustor.

  19. Gaseous microflow modeling using the Fokker-Planck equation

    Science.gov (United States)

    Singh, S. K.; Thantanapally, Chakradhar; Ansumali, Santosh

    2016-12-01

    We present a comparative study of gaseous microflow systems using the recently introduced Fokker-Planck approach and other methods such as: direct simulation Monte Carlo, lattice Boltzmann, and variational solution of Boltzmann-BGK. We show that this Fokker-Plank approach performs efficiently at intermediate values of Knudsen number, a region where direct simulation Monte Carlo becomes expensive and lattice Boltzmann becomes inaccurate. We also investigate the effectiveness of a recently proposed Fokker-Planck model in simulations of heat transfer, as a function of relevant parameters such as the Prandtl, Knudsen numbers. Furthermore, we present simulation of shock wave as a function of Mach number in transonic regime. Our results suggest that the performance of the Fokker-Planck approach is superior to that of the other methods in transition regime for rarefied gas flow and transonic regime for shock wave.

  20. Coupling dynamic of twin supersonic jets

    Science.gov (United States)

    Kuo, Ching-Wen; Cluts, Jordan; Samimy, Mo

    2015-11-01

    In a supersonic shock-containing jet, the interaction of large-scale structures in the jet's shear layer with the shock waves generates acoustic waves. The waves propagate upstream, excite the jet initial shear layer instability, establish a feedback loop at certain conditions, and generate screech noise. The screech normally contains different modes of various strengths. Similarly, twin-jet plumes contain screech tones. If the dynamics of the two jet plumes are synchronized, the screech amplitude could be significantly amplified. There is a proposed analytical model in the literature for screech synchronization in twin rectangular jets. This model shows that with no phase difference in acoustic waves arriving at neighboring nozzle lips, twin-jet plumes feature a strong coupling with a significant level of screech tones. In this work the maximum nozzle separation distance for sustained screech synchronization and strong coupling is analytically derived. This model is used with our round twin-jet experiments and the predicted coupling level agrees well with the experimental results. Near-field microphone measurements and schlieren visualization along with the analytical model are used to investigate the coupling mechanisms of twin supersonic jets. Supported by ONR.

  1. Trends and new developments in gaseous detectors

    CERN Document Server

    Hoch, Michael

    2004-01-01

    Almost one century ago the method of particle detection with gaseous detectors was invented. Since then they have been exploited successfully in many experiments using a wide variety of different applications. The development is still going on today. The underlying working principles are today well understood and with the help of modern simulation techniques, new configurations can be easily examined and optimized before a first experimental test. Traditional wire chamber ensembles demonstrate that they are still up to date and are well prepared to meet also the challenges of LHC. Applications will be discussed using TPCs in high multiplicity environments with standard Multi-Wire Proportional Chamber (MWPC) as readout as well as drift tubes in a muon spectrometer for a Large Hardron Collider (LHC) experiment. Triggered by the evolving printed circuit technology, a new generation of gaseous detectors with very high position resolution and rate capability has emerged. Two representatives (MICROMEGAS, GEM) have ...

  2. Towards spark-proof gaseous pixel detectors

    Science.gov (United States)

    Tsigaridas, S.; Beuzekom, M. v.; Chan, H. W.; Graaf, H. v. d.; Hartjes, F.; Heijhoff, K.; Hessey, N. P.; Prodanovic, V.

    2016-11-01

    The micro-pattern gaseous pixel detector, is a promising technology for imaging and particle tracking applications. It is a combination of a gas layer acting as detection medium and a CMOS pixelated readout-chip. As a prevention against discharges we deposit a protection layer on the chip and then integrate on top a micromegas-like amplification structure. With this technology we are able to reconstruct 3D track segments of particles passing through the gas thanks to the functionality of the chip. We have turned a Timepix3 chip into a gaseous pixel detector and tested it at the SPS at Cern. The preliminary results are promising and within the expectations. However, the spark protection layer needs further improvement to make reliable detectors. For this reason, we have created a setup for spark-testing. We present the first results obtained from the lab-measurements along with preliminary results from the testbeam.

  3. Photosensitive Gaseous Detectors for Cryogenic Temperature Applications

    CERN Document Server

    Periale, L; Iacobaeus, C; Lund-Jensen, B; Picchi, P; Pietropaolo, F

    2007-01-01

    There are several proposals and projects today for building LXe Time Projection Chambers (TPCs) for dark matter search. An important element of these TPCs are the photomultipliers operating either inside LXe or in vapors above the liquid. We have recently demonstrated that photosensitive gaseous detectors (wire type and hole-type) can operate perfectly well until temperatures of LN2. In this paper results of systematic studies of operation of the photosensitive version of these detectors (combined with reflective or semi-transparent CsI photocathodes) in the temperature interval of 300-150 K are presented. In particular, it was demonstrated that both sealed and flushed by a gas detectors could operate at a quite stable fashion in a year/time scale. Obtained results, in particular the long-term stability of photosensitive gaseous detectors, strongly indicate that they can be cheap and simple alternatives to photomultipliers or avalanche solid-state detectors in LXe TPC applications.

  4. Gaseous mediators in resolution of inflammation.

    Science.gov (United States)

    Wallace, John L; Ianaro, Angela; Flannigan, Kyle L; Cirino, Giuseppe

    2015-05-01

    There are numerous gaseous substances that can act as signaling molecules, but the best characterized of these are nitric oxide, hydrogen sulfide and carbon monoxide. Each has been shown to play important roles in many physiological and pathophysiological processes. This article is focused on the effects of these gasotransmitters in the context of inflammation. There is considerable overlap in the actions of nitric oxide, hydrogen sulfide and carbon monoxide with respect to inflammation, and these mediators appear to act primarily as anti-inflammatory substances, promoting resolution of inflammatory processes. They also have protective and pro-healing effects in some tissues, such as the gastrointestinal tract and lung. Over the past two decades, significant progress has been made in the development of novel anti-inflammatory and cytoprotective drugs that release of one or more of these gaseous mediators.

  5. National Gas Survey. Synthesized gaseous hydrocarbon fuels

    Energy Technology Data Exchange (ETDEWEB)

    None

    1978-06-01

    The supply-Technical Advisory Task Force-Synthesized Gaseous Hydrocarbon Fuels considered coal, hydrocarbon liquids, oil shales, tar sands, and bioconvertible materials as potential feedstocks for gaseous fuels. Current status of process technology for each feedstock was reviewed, economic evaluations including sensitivity analysis were made, and constraints for establishment of a synthesized gaseous hydrocarbon fuels industry considered. Process technology is presently available to manufacture gaseous hydrocarbon fuels from each of the feedstocks. In 1975 there were eleven liquid feedstock SNG plants in the United States having a capacity of 1.1 billion SCFD. There can be no contribution of SNG before 1982 from plants using feedstocks other than liquids because there are no plants in operation or under construction as of 1977. Costs for SNG are higher than current regulated prices for U.S. natural gas. Because of large reserves, coal is a prime feedstock candidate although there are major constraints in the area of coal leases, mining and water permits, and others. Commercial technology is available and several new gasification processes are under development. Oil shale is also a feedstock in large supply and commercial process technology is available. There are siting and permit constraints, and water availability may limit the ultimate size of an oil shale processing industry. Under projected conditions, bioconvertible materials are not expected to support the production of large quantities of pipeline quality gas during the next decade. Production of low or medium Btu gas from municipal solid wastes can be expected to be developed in urban areas in conjunction with savings in disposal costs. In the economic evaluations presented, the most significant factor for liquid feedstock plants is the anticipated cost of feedstock and fuel. The economic viability of plants using other feedstocks is primarily dependent upon capital requirements.

  6. Correlation and prediction of gaseous diffusion coefficients.

    Science.gov (United States)

    Marrero, T. R.; Mason, E. A.

    1973-01-01

    A new correlation method for binary gaseous diffusion coefficients from very low temperatures to 10,000 K is proposed based on an extended principle of corresponding states, and having greater range and accuracy than previous correlations. There are two correlation parameters that are related to other physical quantities and that are predictable in the absence of diffusion measurements. Quantum effects and composition dependence are included, but high-pressure effects are not. The results are directly applicable to multicomponent mixtures.

  7. On the origin of impinging tones at low supersonic flow

    CERN Document Server

    Wilke, Robert

    2016-01-01

    Impinging compressible jets may cause deafness and material fatigue due to immensely loud tonal noise. It is generally accepted that a feedback mechanism similar to the screech feedback loop is responsible for impinging tones. The close of the loop remained unclear. One hypothesis hold up in the literature explains the emanated sound with the direct interaction of vortices and the wall. Other explanations name the standoff shock oscillations as the origin of the tones. Using direct numerical simulations (DNS) we were able to identify the source mechanism for under-expanded impinging jets with a nozzle pressure ratio (NPR) of 2.15 and a plate distance of 5 diameters. We found two different types of interactions between vortices and shocks to be responsible for the generation of the impinging tones. They are not related to screech.

  8. Science and Technology Text Mining: Hypersonic and Supersonic Flow

    Science.gov (United States)

    2006-05-31

    Technical Intelligence. Competitive Intelligence Review. 4:1. Kostoff, R. N. (1993b) Co-Word Analysis. in Assessing R&D Impacts: Method and...Management. 24:3. Kostoff, R.N. (1994b). Database Tomography: Origins and Applications. Competitive Intelligence Review 5:1. Spring. Kostoff, R. N

  9. The Effects of Laser Energy Deposition on Supersonic Cavity Flow

    Science.gov (United States)

    2009-01-01

    to be 1.246. K is taken as 0.55 for this cavity configuration (Hankey and Shang, 1979). For the computations, one of the Beowulf computer clusters of...zone are 95 X 54 X 35. and 177 X 62 X 70 in the outside zone, in the x, y. z directions, respectively. Grid clustering was employed at several places in...Rutgers University (mphase) was used. The core of the mphase cluster consists of 60 dual and single processor Linux machines. A total of 32 processors

  10. Development of Methods for Diagnostics of Discharges in Supersonic Flows

    Science.gov (United States)

    2001-09-01

    the interaction both with ions, and with electrons are taken into account. The central part of a line is well described in shock approximation, on wings ...two sphenoid ionization tracks behind the cathode and anode iafS DVC ν2≈> Sf CV≈αsin Stationary discharge Alternating discharge S f break steady C

  11. Prediction and control of vortex-dominated and vortex-wake flows

    Science.gov (United States)

    Kandil, Osama

    1993-01-01

    This progress report documents the accomplishments achieved in the period from December 1, 1992 until November 30, 1993. These accomplishments include publications, national and international presentations, NASA presentations, and the research group supported under this grant. Topics covered by documents incorporated into this progress report include: active control of asymmetric conical flow using spinning and rotary oscillation; supersonic vortex breakdown over a delta wing in transonic flow; shock-vortex interaction over a 65-degree delta wing in transonic flow; three dimensional supersonic vortex breakdown; numerical simulation and physical aspects of supersonic vortex breakdown; and prediction of asymmetric vortical flows around slender bodies using Navier-Stokes equations.

  12. Supersonic beams at high particle densities: model description beyond the ideal gas approximation.

    Science.gov (United States)

    Christen, Wolfgang; Rademann, Klaus; Even, Uzi

    2010-10-28

    Supersonic molecular beams constitute a very powerful technique in modern chemical physics. They offer several unique features such as a directed, collision-free flow of particles, very high luminosity, and an unsurpassed strong adiabatic cooling during the jet expansion. While it is generally recognized that their maximum flow velocity depends on the molecular weight and the temperature of the working fluid in the stagnation reservoir, not a lot is known on the effects of elevated particle densities. Frequently, the characteristics of supersonic beams are treated in diverse approximations of an ideal gas expansion. In these simplified model descriptions, the real gas character of fluid systems is ignored, although particle associations are responsible for fundamental processes such as the formation of clusters, both in the reservoir at increased densities and during the jet expansion. In this contribution, the various assumptions of ideal gas treatments of supersonic beams and their shortcomings are reviewed. It is shown in detail that a straightforward thermodynamic approach considering the initial and final enthalpy is capable of characterizing the terminal mean beam velocity, even at the liquid-vapor phase boundary and the critical point. Fluid properties are obtained using the most accurate equations of state available at present. This procedure provides the opportunity to naturally include the dramatic effects of nonideal gas behavior for a large variety of fluid systems. Besides the prediction of the terminal flow velocity, thermodynamic models of isentropic jet expansions permit an estimate of the upper limit of the beam temperature and the amount of condensation in the beam. These descriptions can even be extended to include spinodal decomposition processes, thus providing a generally applicable tool for investigating the two-phase region of high supersaturations not easily accessible otherwise.

  13. An Introduction to the Supersonic Molecular Beam Injection

    Institute of Scientific and Technical Information of China (English)

    2001-01-01

    Recently a new fuelling method with supersonic molecular beam injection (MBI) has been developed and used in the tokamaks experiments successfully. It is economical to develop and maintain. The advantages of supersonic MBI compared with the conventional of gas-puffing method are as follows: deep deposition of fuel, better fuelling efficiency, reduced recycling and pure plasma. Particle and energy confinement can be improved and density limit extended. This review described the Laval nozzle molecular beam and a simple collective model for the injection of a supersonic MBI into the tokamak plasma.

  14. Modeling of turbulent supersonic H2-air combustion with a multivariate beta PDF

    Science.gov (United States)

    Baurle, R. A.; Hassan, H. A.

    1993-01-01

    Recent calculations of turbulent supersonic reacting shear flows using an assumed multivariate beta PDF (probability density function) resulted in reduced production rates and a delay in the onset of combustion. This result is not consistent with available measurements. The present research explores two possible reasons for this behavior: use of PDF's that do not yield Favre averaged quantities, and the gradient diffusion assumption. A new multivariate beta PDF involving species densities is introduced which makes it possible to compute Favre averaged mass fractions. However, using this PDF did not improve comparisons with experiment. A countergradient diffusion model is then introduced. Preliminary calculations suggest this to be the cause of the discrepancy.

  15. Computational Comparison of the Interaction of a Lateral Jet on a Supersonic Generic Missile

    OpenAIRE

    Gnemmi, Patrick; Adeli, Reza; Longo, José Maria

    2008-01-01

    The paper deals with the comparison of computations made at DLR and ISL on the interaction between a lateral jet issuing from a generic missile body and the oncoming supersonic cross-flow. Steady-state numerical simulations are carried out by 3D, viscous, turbulent, Reynolds-Averaged Navier-Stokes Codes; at DLR, a hybrid mesh is used for the TAU calculation, whereas at ISL a hexahedral mesh is used for the CFX computation. Experimental data acquired in the DLR wind tunnel TMK in Cologne act a...

  16. EVOLUTION OF A 2-D DISTURBANCE IN A SUPERSONIC BOUNDARY LAYER AND THE GENERATION OF SHOCKLETS

    Institute of Scientific and Technical Information of China (English)

    黄章峰; 周恒

    2004-01-01

    Through direct numerical simulation, the evolution of a 2-D disturbance in a supersonic boundary layer has been investigated. At a chosen location, a small amplitude T-S wave was fed into the boundary layer to investigate its evolution. Characteristics of nonlinear evolution have been found. Two methods were applied for the detection of shocklets ,and it was found that when the amplitude of the disturbance reached a certain value,shocklets would be generated, which should be taken into consideration when nonlinear theory of hydrodynamic stability for compressible flows is to be established.

  17. NUMERICAL INVESTIGATION OF EVOLUTION OF DISTURBANCES IN SUPERSONIC SHARP CONE BOUNDARY LAYERS

    Institute of Scientific and Technical Information of China (English)

    DONG Ming; LUO Ji-sheng; CAO Wei

    2006-01-01

    The spatial evolution of 2-D disturbances in supersonic sharp cone boundary layers was investigated by direct numerical simulation (DNS) in high order compact difference scheme. The results suggested that, although the normal velocity in the sharp cone boundary layer was not small, the evolution of amplitude and phase for small amplitude disturbances would be well in accordance with the results obtained by the linear stability theory (LST) which supposes the flow was parallel. The evolution of some finite amplitude disturbances was also investigated, and the characteristic of the evolution was shown. Shocklets were also found when the amplitude of disturbances increased over some value.

  18. Pulsed rotating supersonic source used with merged molecular beams

    CERN Document Server

    Sheffield, L; Krasovitskiy, V; Rathnayaka, K D D; Lyuksyutov, I F; Herschbach, D R

    2012-01-01

    We describe a pulsed rotating supersonic beam source, evolved from an ancestral device [M. Gupta and D. Herschbach, J. Phys. Chem. A 105, 1626 (2001)]. The beam emerges from a nozzle near the tip of a hollow rotor which can be spun at high-speed to shift the molecular velocity distribution downward or upward over a wide range. Here we consider mostly the slowing mode. Introducing a pulsed gas inlet system, cryocooling, and a shutter gate eliminated the main handicap of the original device, in which continuous gas flow imposed high background pressure. The new version provides intense pulses, of duration 0.1-0.6 ms (depending on rotor speed) and containing ~10^12 molecules at lab speeds as low as 35 m/s and ~ 10^15 molecules at 400 m/s. Beams of any molecule available as a gas can be slowed (or speeded); e.g., we have produced slow and fast beams of rare gases, O2, Cl2, NO2, NH3, and SF6. For collision experiments, the ability to scan the beam speed by merely adjusting the rotor is especially advantageous when...

  19. Effects of streamwise vortex breakdown on supersonic combustion.

    Science.gov (United States)

    Hiejima, Toshihiko

    2016-04-01

    This paper presents a numerical simulation study of the combustion structure of streamwise vortex breakdown at Mach number 2.48. Hydrogen fuel is injected into a combustor at sonic speed from the rear of a hypermixer strut that can generate streamwise vortices. The results show that the burning behavior is enhanced at the points of the shock waves that are incident on the vortex and therefore the vortex breakdown in the subsonic region occurs due to combustion. The breakdown domain in the mainstream is found to form a flame-holding region suited to combustion and to lead to a stable combustion field with detached flames. In this way, streamwise vortex breakdown has an essential role in combustion enhancement and the formation of flames that hold under supersonic inflow conditions. Finally, the combustion property defined here is shown to coincide with the produced-water mass flow. This property shows that the amount of combustion is saturated at equivalence ratios over 0.4, although there is a slight increase beyond 1.

  20. Characteristics of Supersonic Closed Loop with Disk CCMHD Generator

    Science.gov (United States)

    Yamasaki, Hiroyuki; Murakami, Tomoyuki; Okuno, Yoshihiro

    Results of experimental study on performance of the supersonic closed loop with a disk MHD generator are described. The high temperature (> 1900K) argon circulation was carried out successfully during 2.4 hours. The heat gain and loss of argon was investigated, and a large heat loss was found at the diffuser and the exhausting duct although an energy efficiency of recuperator was high. The large heat loss was ascribed to water cooling at the diffuser and the exhausting duct. At the same time, the enhancement of heat transfer coefficient was suggested. The argon temperature and the heat loss calculated under an assumption of four times larger heat transfer coefficient have shown a good agreement with experimental ones. The pressure ratio inside the loop was discussed, and the result has indicated that the total pressure at the upstream of nozzle throat is decided by the total temperature and the mass flow. On the other hand, the total pressure at the downstream is determined by the total mass in the loop and the total pressure at the upstream. The first power generation was carried out, and a good correlation between the load resistance and the Hall voltage was observed. However, the power output remained very small.