X-43 Hypersonic Vehicle Technology Development

Science.gov (United States)

Voland, Randall T.; Huebner, Lawrence D.; McClinton, Charles R.

2005-01-01

NASA recently completed two major programs in Hypersonics: Hyper-X, with the record-breaking flights of the X-43A, and the Next Generation Launch Technology (NGLT) Program. The X-43A flights, the culmination of the Hyper-X Program, were the first-ever examples of a scramjet engine propelling a hypersonic vehicle and provided unique, convincing, detailed flight data required to validate the design tools needed for design and development of future operational hypersonic airbreathing vehicles. Concurrent with Hyper-X, NASA's NGLT Program focused on technologies needed for future revolutionary launch vehicles. The NGLT was "competed" by NASA in response to the President s redirection of the agency to space exploration, after making significant progress towards maturing technologies required to enable airbreathing hypersonic launch vehicles. NGLT quantified the benefits, identified technology needs, developed airframe and propulsion technology, chartered a broad University base, and developed detailed plans to mature and validate hypersonic airbreathing technology for space access. NASA is currently in the process of defining plans for a new Hypersonic Technology Program. Details of that plan are not currently available. This paper highlights results from the successful Mach 7 and 10 flights of the X-43A, and the current state of hypersonic technology.

New Hypersonic Shock Tunnel at the Laboratory of Aerothermodynamics and Hypersonics Prof. Henry T. Nagamatsu

International Nuclear Information System (INIS)

Toro, P. G. P.; Minucci, M. A. S.; Chanes, J. B. Jr; Oliveira, A. C.; Gomes, F. A. A.; Myrabo, L. N.; Nagamatsu, Henry T.

2008-01-01

The new 0.60-m. nozzle exit diameter hypersonic shock tunnel was designed to study advanced air-breathing propulsion system such as supersonic combustion and/or laser technologies. In addition, it may be used for hypersonic flow studies and investigations of the electromagnetic (laser) energy addition for flow control. This new hypersonic shock tunnel was designed and installed at the Laboratory for of Aerothermodynamics and Hypersonics Prof. Henry T. Nagamatsu, IEAv-CTA, Brazil. The design of the tunnel enables relatively long test times, 2-10 milliseconds, suitable for the experiments performed at the laboratory. Free stream Mach numbers ranging from 6 to 25 can be produced and stagnation pressures and temperatures up to 360 atm. and up to 9,000 K, respectively, can be generated. Shadowgraph and schlieren optical techniques will be used for flow visualization

Radiation-driven winds in x-ray binaries

International Nuclear Information System (INIS)

Friend, D.B.; Castor, J.I.

1982-01-01

We discuss the properties of a radiation-driven stellar wind in an X-ray binary system. The Castor, Abbott, Klein line-driven wind model is used, but the effects of the compact companion (gravity and continuum radiation pressure) and the centrifugal force due to orbital motion are included. These forces destroy the spherical symmetry of the wind and can make the mass loss and accretion strong functions of the size of the primary relative to its critical potential lobe. We in most systems the wind alone could power the X-ray emission. It also appears that, in the evolution of these systems, there would be a continuous transition from wind accretion to critical potential lobe overflow. The model is also used to make a prediction about the nature of a suspected binary system which is not known to be an X-ray emitter

Hypersonic Materials and Structures

Science.gov (United States)

Glass, David E.

2016-01-01

Thermal protection systems (TPS) and hot structures are required for a range of hypersonic vehicles ranging from ballistic reentry to hypersonic cruise vehicles, both within Earth's atmosphere and non-Earth atmospheres. The focus of this presentation is on air breathing hypersonic vehicles in the Earth's atmosphere. This includes single-stage to orbit (SSTO), two-stage to orbit (TSTO) accelerators, access to space vehicles, and hypersonic cruise vehicles. This paper will start out with a brief discussion of aerodynamic heating and thermal management techniques to address the high heating, followed by an overview of TPS for rocket-launched and air-breathing vehicles. The argument is presented that as we move from rocket-based vehicles to air-breathing vehicles, we need to move away from the insulated airplane approach used on the Space Shuttle Orbiter to a wide range of TPS and hot structure approaches. The primary portion of the paper will discuss issues and design options for CMC TPS and hot structure components, including leading edges, acreage TPS, and control surfaces. The current state-of-the-art will be briefly discussed for some of the components.

Simplified Thermo-Chemical Modelling For Hypersonic Flow

Science.gov (United States)

Sancho, Jorge; Alvarez, Paula; Gonzalez, Ezequiel; Rodriguez, Manuel

2011-05-01

Hypersonic flows are connected with high temperatures, generally associated with strong shock waves that appear in such flows. At high temperatures vibrational degrees of freedom of the molecules may become excited, the molecules may dissociate into atoms, the molecules or free atoms may ionize, and molecular or ionic species, unimportant at lower temperatures, may be formed. In order to take into account these effects, a chemical model is needed, but this model should be simplified in order to be handled by a CFD code, but with a sufficient precision to take into account the physics more important. This work is related to a chemical non-equilibrium model validation, implemented into a commercial CFD code, in order to obtain the flow field around bodies in hypersonic flow. The selected non-equilibrium model is composed of seven species and six direct reactions together with their inverse. The commercial CFD code where the non- equilibrium model has been implemented is FLUENT. For the validation, the X38/Sphynx Mach 20 case is rebuilt on a reduced geometry, including the 1/3 Lref forebody. This case has been run in laminar regime, non catalytic wall and with radiative equilibrium wall temperature. The validated non-equilibrium model is applied to the EXPERT (European Experimental Re-entry Test-bed) vehicle at a specified trajectory point (Mach number 14). This case has been run also in laminar regime, non catalytic wall and with radiative equilibrium wall temperature.

TBCC Discipline Overview. Hypersonics Project

Science.gov (United States)

Thomas, Scott R.

2011-01-01

The "National Aeronautics Research and Development Policy" document, issued by the National Science and Technology Council in December 2006, stated that one (among several) of the guiding objectives of the federal aeronautics research and development endeavors shall be stable and long-term foundational research efforts. Nearly concurrently, the National Academies issued a more technically focused aeronautics blueprint, entitled: the "Decadal Survey of Civil Aeronautics - Foundations for the Future." Taken together these documents outline the principles of an aeronautics maturation plan. Thus, in response to these overarching inputs (and others), the National Aeronautics and Space Administration (NASA) organized the Fundamental Aeronautics Program (FAP), a program within the NASA Aeronautics Research Mission Directorate (ARMD). The FAP initiated foundational research and technology development tasks to enable the capability of future vehicles that operate across a broad range of Mach numbers, inclusive of the subsonic, supersonic, and hypersonic flight regimes. The FAP Hypersonics Project concentrates on two hypersonic missions: (1) Air-breathing Access to Space (AAS) and (2) the (Planetary Atmospheric) Entry, Decent, and Landing (EDL). The AAS mission focuses on Two-Stage-To-Orbit (TSTO) systems using air-breathing combined-cycle-engine propulsion; whereas, the EDL mission focuses on the challenges associated with delivering large payloads to (and from) Mars. So, the FAP Hypersonic Project investments are aligned to achieve mastery and intellectual stewardship of the core competencies in the hypersonic-flight regime, which ultimately will be required for practical systems with highly integrated aerodynamic/vehicle and propulsion/engine technologies. Within the FAP Hypersonics, the technology management is further divided into disciplines including one targeting Turbine-Based Combine-Cycle (TBCC) propulsion. Additionally, to obtain expertise and support from outside

Hypersonic sliding target tracking in near space

Directory of Open Access Journals (Sweden)

Xiang-yu Zhang

2015-12-01

Full Text Available To improve the tracking accuracy of hypersonic sliding target in near space, the influence of target hypersonic movement on radar detection and tracking is analyzed, and an IMM tracking algorithm is proposed based on radial velocity compensating and cancellation processing of high dynamic biases under the earth centered earth fixed (ECEF coordinate. Based on the analysis of effect of target hypersonic movement, a measurement model is constructed to reduce the filter divergence which is caused by the model mismatch. The high dynamic biases due to the target hypersonic movement are approximately compensated through radial velocity estimation to achieve the hypersonic target tracking at low systematic biases in near space. The high dynamic biases are further eliminated by the cancellation processing of different radars, in which the track association problem can be solved when the dynamic biases are low. An IMM algorithm based on constant acceleration (CA, constant turning (CT and Singer models is used to achieve the hypersonic sliding target tracking in near space. Simulation results show that the target tracking in near space can be achieved more effectively by using the proposed algorithm.

Numerical simulation of hypersonic flight experiment vehicle

OpenAIRE

Yamamoto, Yukimitsu; Yoshioka, Minako; 山本　行光; 吉岡　美菜子

1994-01-01

Hypersonic aerodynamic characteristics of Hypersonic FLight EXperiment (HYFLEX vehicle were investigated by numerical simulations using Navier-Stokes CFD (Computational Fluid Dynamics) code of NAL. Numerical results were compared with experimental data obtained at Hypersonic Wind Tunnel at NAL. In order to investigate real flight aerodynamic characteristics. numerical calculations corresponding to the flight conditions suffering from maximum aero thermodynamic heating were also made and the d...

Anisotropic power spectrum of refractive-index fluctuation in hypersonic turbulence.

Science.gov (United States)

Li, Jiangting; Yang, Shaofei; Guo, Lixin; Cheng, Mingjian

2016-11-10

An anisotropic power spectrum of the refractive-index fluctuation in hypersonic turbulence was obtained by processing the experimental image of the hypersonic plasma sheath and transforming the generalized anisotropic von Kármán spectrum. The power spectrum suggested here can provide as good a fit to measured spectrum data for hypersonic turbulence as that recorded from the nano-planar laser scattering image. Based on the newfound anisotropic hypersonic turbulence power spectrum, Rytov approximation was employed to establish the wave structure function and the spatial coherence radius model of electromagnetic beam propagation in hypersonic turbulence. Enhancing the anisotropy characteristics of the hypersonic turbulence led to a significant improvement in the propagation performance of electromagnetic beams in hypersonic plasma sheath. The influence of hypersonic turbulence on electromagnetic beams increases with the increase of variance of the refractive-index fluctuation and the decrease of turbulence outer scale and anisotropy parameters. The spatial coherence radius was much smaller than that in atmospheric turbulence. These results are fundamental to understanding electromagnetic wave propagation in hypersonic turbulence.

Modelling of Influence of Hypersonic Conditions on Gyroscopic Inertial Navigation Sensor Suspension

Directory of Open Access Journals (Sweden)

Korobiichuk Igor

2017-06-01

Full Text Available The upcoming hypersonic technologies pose a difficult task for air navigation systems. The article presents a designed model of elastic interaction of penetrating acoustic radiation with flat isotropic suspension elements of an inertial navigation sensor in the operational conditions of hypersonic flight. It has been shown that the acoustic transparency effect in the form of a spatial-frequency resonance becomes possible with simultaneous manifestation of the wave coincidence condition in the acoustic field and equality of the natural oscillation frequency of a finite-size plate and a forced oscillation frequency of an infinite plate. The effect can lead to additional measurement errors of the navigation system. Using the model, the worst and best case suspension oscillation frequencies can be determined, which will help during the design of a navigation system.

Modeling, Measurements, and Fundamental Database Development for Nonequilibrium Hypersonic Aerothermodynamics

Science.gov (United States)

Bose, Deepak

2012-01-01

The design of entry vehicles requires predictions of aerothermal environment during the hypersonic phase of their flight trajectories. These predictions are made using computational fluid dynamics (CFD) codes that often rely on physics and chemistry models of nonequilibrium processes. The primary processes of interest are gas phase chemistry, internal energy relaxation, electronic excitation, nonequilibrium emission and absorption of radiation, and gas-surface interaction leading to surface recession and catalytic recombination. NASAs Hypersonics Project is advancing the state-of-the-art in modeling of nonequilibrium phenomena by making detailed spectroscopic measurements in shock tube and arcjets, using ab-initio quantum mechanical techniques develop fundamental chemistry and spectroscopic databases, making fundamental measurements of finite-rate gas surface interactions, implementing of detailed mechanisms in the state-of-the-art CFD codes, The development of new models is based on validation with relevant experiments. We will present the latest developments and a roadmap for the technical areas mentioned above

Stabilization of the hypersonic boundary layer by finite-amplitude streaks

Science.gov (United States)

Ren, Jie; Fu, Song; Hanifi, Ardeshir

2016-02-01

Stabilization of two-dimensional disturbances in hypersonic boundary layer flows by finite-amplitude streaks is investigated using nonlinear parabolized stability equations. The boundary-layer flows at Mach numbers 4.5 and 6.0 are studied in which both first and second modes are supported. The streaks considered here are driven either by the so-called optimal perturbations (Klebanoff-type) or the centrifugal instability (Görtler-type). When the streak amplitude is in an appropriate range, i.e., large enough to modulate the laminar boundary layer but low enough to not trigger secondary instability, both first and second modes can effectively be suppressed.

Density ratios in compressions driven by radiation pressure

International Nuclear Information System (INIS)

Lee, S.

1988-01-01

It has been suggested that in the cannonball scheme of laser compression the pellet may be considered to be compressed by the 'brute force' of the radiation pressure. For such a radiation-driven compression, an energy balance method is applied to give an equation fixing the radius compression ratio K which is a key parameter for such intense compressions. A shock model is used to yield specific results. For a square-pulse driving power compressing a spherical pellet with a specific heat ratio of 5/3, a density compression ratio Γ of 27 is computed. Double (stepped) pulsing with linearly rising power enhances Γ to 1750. The value of Γ is not dependent on the absolute magnitude of the piston power, as long as this is large enough. Further enhancement of compression by multiple (stepped) pulsing becomes obvious. The enhanced compression increases the energy gain factor G for a 100 μm DT pellet driven by radiation power of 10 16 W from 6 for a square pulse power with 0.5 MJ absorbed energy to 90 for a double (stepped) linearly rising pulse with absorbed energy of 0.4 MJ assuming perfect coupling efficiency. (author)

CFD applications in hypersonic flight

Science.gov (United States)

Edwards, T. A.

1992-01-01

Design studies are underway for a variety of hypersonic flight vehicles. The National Aero-Space Plane will provide a reusable, single-stage-to-orbit capability for routine access to low earth orbit. Flight-capable satellites will dip into the atmosphere to maneuver to new orbits, while planetary probes will decelerate at their destination by atmospheric aerobraking. To supplement limited experimental capabilities in the hypersonic regime, CFD is being used to analyze the flow about these configurations. The governing equations include fluid dynamic as well as chemical species equations, which are solved with robust upwind differencing schemes. Examples of CFD applications to hypersonic vehicles suggest an important role this technology will play in the development of future aerospace systems. The computational resources needed to obtain solutions are large, but various strategies are being exploited to reduce the time required for complete vehicle simulations.

Numerical investigation on target implosions driven by radiation ablation and shock compression in dynamic hohlraums

Energy Technology Data Exchange (ETDEWEB)

Xiao, Delong; Sun, Shunkai; Zhao, Yingkui; Ding, Ning; Wu, Jiming; Dai, Zihuan; Yin, Li; Zhang, Yang; Xue, Chuang [Institute of Applied Physics and Computational Mathematics, Beijing 100088 (China)

2015-05-15

In a dynamic hohlraum driven inertial confinement fusion (ICF) configuration, the target may experience two different kinds of implosions. One is driven by hohlraum radiation ablation, which is approximately symmetric at the equator and poles. The second is caused by the radiating shock produced in Z-pinch dynamic hohlraums, only taking place at the equator. To gain a symmetrical target implosion driven by radiation ablation and avoid asymmetric shock compression is a crucial issue in driving ICF using dynamic hohlraums. It is known that when the target is heated by hohlraum radiation, the ablated plasma will expand outward. The pressure in the shocked converter plasma qualitatively varies linearly with the material temperature. However, the ablation pressure in the ablated plasma varies with 3.5 power of the hohlraum radiation temperature. Therefore, as the hohlraum temperature increases, the ablation pressure will eventually exceed the shock pressure, and the expansion of the ablated plasma will obviously weaken the shock propagation and decrease its velocity after propagating into the ablator plasma. Consequently, longer time duration is provided for the symmetrical target implosion driven by radiation ablation. In this paper these processes are numerically investigated by changing drive currents or varying load parameters. The simulation results show that a critical hohlraum radiation temperature is needed to provide a high enough ablation pressure to decelerate the shock, thus providing long enough time duration for the symmetric fuel compression driven by radiation ablation.

High power radiation guiding systems for laser driven accelerators

International Nuclear Information System (INIS)

Cutolo, A.

1985-01-01

This paper reviews the main problems encountered in the design of an optical system for transmitting high fluence radiation in a laser driven accelerator. Particular attention is devoted to the analysis of mirror and waveguide systems. (orig.)

Overview of hypersonic CFD code calibration studies

Science.gov (United States)

Miller, Charles G.

1987-01-01

The topics are presented in viewgraph form and include the following: definitions of computational fluid dynamics (CFD) code validation; climate in hypersonics and LaRC when first 'designed' CFD code calibration studied was initiated; methodology from the experimentalist's perspective; hypersonic facilities; measurement techniques; and CFD code calibration studies.

Unstart Coupling Mechanism Analysis of Multiple-Modules Hypersonic Inlet

Directory of Open Access Journals (Sweden)

Jichao Hu

2013-01-01

Full Text Available The combination of multiplemodules in parallel manner is an important way to achieve the much higher thrust of scramjet engine. For the multiple-modules scramjet engine, when inlet unstarted oscillatory flow appears in a single-module engine due to high backpressure, how to interact with each module by massflow spillage, and whether inlet unstart occurs in other modules are important issues. The unstarted flowfield and coupling characteristic for a three-module hypersonic inlet caused by center module II and side module III were, conducted respectively. The results indicate that the other two hypersonic inlets are forced into unstarted flow when unstarted phenomenon appears on a single-module hypersonic inlet due to high backpressure, and the reversed flow in the isolator dominates the formation, expansion, shrinkage, and disappearance of the vortexes, and thus, it is the major factor of unstart coupling of multiple-modules hypersonic inlet. The coupling effect among multiple modules makes hypersonic inlet be more likely unstarted.

Unstart coupling mechanism analysis of multiple-modules hypersonic inlet.

Science.gov (United States)

Hu, Jichao; Chang, Juntao; Wang, Lei; Cao, Shibin; Bao, Wen

2013-01-01

The combination of multiplemodules in parallel manner is an important way to achieve the much higher thrust of scramjet engine. For the multiple-modules scramjet engine, when inlet unstarted oscillatory flow appears in a single-module engine due to high backpressure, how to interact with each module by massflow spillage, and whether inlet unstart occurs in other modules are important issues. The unstarted flowfield and coupling characteristic for a three-module hypersonic inlet caused by center module II and side module III were, conducted respectively. The results indicate that the other two hypersonic inlets are forced into unstarted flow when unstarted phenomenon appears on a single-module hypersonic inlet due to high backpressure, and the reversed flow in the isolator dominates the formation, expansion, shrinkage, and disappearance of the vortexes, and thus, it is the major factor of unstart coupling of multiple-modules hypersonic inlet. The coupling effect among multiple modules makes hypersonic inlet be more likely unstarted.

Heat removing under hypersonic conditions

Directory of Open Access Journals (Sweden)

Semenov Mikhail E.

2016-01-01

Full Text Available In this paper we consider the heat transfer properties of the axially symmetric body with parabolic shape at hypersonic speeds (with a Mach number M > 5. We use the numerical methods based on the implicit difference scheme (Fedorenko method with direct method based on LU-decomposition and iterative method based on the Gauss-Seigel method. Our numerical results show that the heat removing process should be performed in accordance with the nonlinear law of heat distribution over the surface taking into account the hypersonic conditions of motion.

Retooling CFD for hypersonic aircraft

Science.gov (United States)

Dwoyer, Douglas L.; Kutler, Paul; Povinelli, Louis A.

1987-01-01

The CFD facility requirements of hypersonic aircraft configuration design development are different from those thus far employed for reentry vehicle design, because (1) the airframe and the propulsion system must be fully integrated to achieve the desired performance; (2) the vehicle must be reusable, with minimum refurbishment requirements between flights; and (3) vehicle performance must be optimized for a wide range of Mach numbers. An evaluation is presently made of flow resolution within shock waves, transition and turbulence phenomenon tractability, chemical reaction modeling, and hypersonic boundary layer transition, with state-of-the-art CFD.

Physics of radiation-driven islands near the tokamak density limit

International Nuclear Information System (INIS)

Gates, D.A.; Delgado-Aparicio, L.; White, R.B.

2013-01-01

In previous work (Gates and Delgado-Aparicio 2012 Phys. Rev. Lett. 108 165004), the onset criterion for radiation-driven islands (Rebut et al 1985 Proc. 10th Int. Conf. on Plasma Physics and Controlled Nuclear Fusion Research 1984 (London, UK, 1984) vol 2 (Vienna: IAEA) p 197) in combination with a simple cylindrical model of tokamak current channel behaviour was shown to be consistent with the empirical scaling of the tokamak density limit (Greenwald et al 1988 Nucl. Fusion 28 2199). A number of the unexplained phenomena at the density limit are consistent with this novel physics mechanism. In this work, a more formal theoretical underpinning, consistent with cylindrical tearing mode theory, is developed for the onset criteria of these modes. The appropriate derivation of the radiation-driven addition to the modified Rutherford equation (MRE) is discussed. Additionally, the ordering of the terms in the MRE is examined in a regime near the density limit. It is hoped that, given the apparent success of this simple model in explaining the observed global scalings, it will lead to a more comprehensive analysis of the possibility that radiation-driven islands are the physics mechanism responsible for the density limit. In particular, with modern diagnostic capabilities detailed measurements of current densities, electron densities and impurity concentrations at rational surfaces should be possible, enabling verification of the concepts described above. (paper)

Aerothermodynamic shape optimization of hypersonic blunt bodies

Science.gov (United States)

Eyi, Sinan; Yumuşak, Mine

2015-07-01

The aim of this study is to develop a reliable and efficient design tool that can be used in hypersonic flows. The flow analysis is based on the axisymmetric Euler/Navier-Stokes and finite-rate chemical reaction equations. The equations are coupled simultaneously and solved implicitly using Newton's method. The Jacobian matrix is evaluated analytically. A gradient-based numerical optimization is used. The adjoint method is utilized for sensitivity calculations. The objective of the design is to generate a hypersonic blunt geometry that produces the minimum drag with low aerodynamic heating. Bezier curves are used for geometry parameterization. The performances of the design optimization method are demonstrated for different hypersonic flow conditions.

DNS Studies of Transitional Hypersonic Reacting Flows Over 3-D Hypersonic Vehicles

National Research Council Canada - National Science Library

Zhong, Xiaolin

2003-01-01

The objectives of this research project are to develop CFD techniques and to conduct DNS studies of fundamental flow physics leading to boundary-layer instability and transition in hypersonic flows...

Experimental Investigation of Brazilian 14-X B Hypersonic Scramjet Aerospace Vehicle

OpenAIRE

de Araujo Martos, João Felipe; da Silveira Rêgo, Israel; Pachon Laiton, Sergio Nicholas; Lima, Bruno Coelho; Costa, Felipe Jean; de Paula Toro, Paulo Gilberto

2017-01-01

The Brazilian hypersonic scramjet aerospace vehicle 14-X B is a technological demonstrator of a hypersonic airbreathing propulsion system based on the supersonic combustion (scramjet) to be tested in flight into the Earth’s atmosphere at an altitude of 30 km and Mach number 7. The 14-X B has been designed at the Prof. Henry T. Nagamatsu Laboratory of Aerothermodynamics and Hypersonics, Institute for Advanced Studies (IEAv), Brazil. The IEAv T3 Hypersonic Shock Tunnel is a ground-test facility...

Experimental Investigation of Hypersonic Flow and Plasma Aerodynamic Actuation Interaction

International Nuclear Information System (INIS)

Sun Quan; Cheng Bangqin; Li Yinghong; Cui Wei; Yu Yonggui; Jie Junhun

2013-01-01

For hypersonic flow, it was found that the most effective plasma actuator is derived from an electromagnetic perturbation. An experimental study was performed between hypersonic flow and plasma aerodynamic actuation interaction in a hypersonic shock tunnel, in which a Mach number of 7 was reached. The plasma discharging characteristic was acquired in static flows. In a hypersonic flow, the flow field can affect the plasma discharging characteristics. DC discharging without magnetic force is unstable, and the discharge channel cannot be maintained. When there is a magnetic field, the energy consumption of the plasma source is approximately three to four times larger than that without a magnetic field, and at the same time plasma discharge can also affect the hypersonic flow field. Through schlieren pictures and pressure measurement, it was found that plasma discharging could induce shockwaves and change the total pressure and wall pressure of the flow field

Improved Dutch Roll Approximation for Hypersonic Vehicle

Directory of Open Access Journals (Sweden)

Liang-Liang Yin

2014-06-01

Full Text Available An improved dutch roll approximation for hypersonic vehicle is presented. From the new approximations, the dutch roll frequency is shown to be a function of the stability axis yaw stability and the dutch roll damping is mainly effected by the roll damping ratio. In additional, an important parameter called roll-to-yaw ratio is obtained to describe the dutch roll mode. Solution shows that large-roll-to-yaw ratio is the generate character of hypersonic vehicle, which results the large error for the practical approximation. Predictions from the literal approximations derived in this paper are compared with actual numerical values for s example hypersonic vehicle, results show the approximations work well and the error is below 10 %.

Hypersonic drone design: A multidisciplinary experience

Science.gov (United States)

1988-01-01

Efforts were focused on design problems of an unmanned hypersonic vehicle. It is felt that a scaled hypersonic drone is necessary to bridge the gap between present theory on hypersonics and the future reality of the National Aerospace Plane (NASP) for two reasons: to fulfill a need for experimental data in the hypersonic regime, and to provide a testbed for the scramjet engine which is to be the primary mode of propulsion for the NASP. Three areas of great concern to NASP design were examined: propulsion, thermal management, and flight systems. Problem solving in these areas was directed towards design of the drone with the idea that the same design techniques could be applied to the NASP. A seventy degree swept double delta wing configuration, developed in the 70's at NASA Langley, was chosen as the aerodynamic and geometric model for the drone. This vehicle would be air-launched from a B-1 at Mach 0.8 and 48,000 feet, rocket boosted by two internal engines to Mach 10 and 100,000 feet, and allowed to cruise under power of the scramjet engine until burnout. It would then return to base for an unpowered landing. Preliminary energy calculations based upon the flight requirements give the drone a gross launch weight of 134,000 lb. and an overall length of 85 feet.

Magnetic fields driven by tidal mixing in radiative stars

Science.gov (United States)

Vidal, Jérémie; Cébron, David; Schaeffer, Nathanaël; Hollerbach, Rainer

2018-04-01

Stellar magnetism plays an important role in stellar evolution theory. Approximatively 10 per cent of observed main sequence (MS) and pre-main-sequence (PMS) radiative stars exhibit surface magnetic fields above the detection limit, raising the question of their origin. These stars host outer radiative envelopes, which are stably stratified. Therefore, they are assumed to be motionless in standard models of stellar structure and evolution. We focus on rapidly rotating, radiative stars which may be prone to the tidal instability, due to an orbital companion. Using direct numerical simulations in a sphere, we study the interplay between a stable stratification and the tidal instability, and assess its dynamo capability. We show that the tidal instability is triggered regardless of the strength of the stratification (Brunt-Väisälä frequency). Furthermore, the tidal instability can lead to both mixing and self-induced magnetic fields in stably stratified layers (provided that the Brunt-Väisälä frequency does not exceed the stellar spin rate in the simulations too much). The application to stars suggests that the resulting magnetic fields could be observable at the stellar surfaces. Indeed, we expect magnetic field strengths up to several Gauss. Consequently, tidally driven dynamos should be considered as a (complementary) dynamo mechanism, possibly operating in radiative MS and PMS stars hosting orbital companions. In particular, tidally driven dynamos may explain the observed magnetism of tidally deformed and rapidly rotating Vega-like stars.

Conjugate Heat Transfer Study in Hypersonic Flows

Science.gov (United States)

Sahoo, Niranjan; Kulkarni, Vinayak; Peetala, Ravi Kumar

2018-04-01

Coupled and decoupled conjugate heat transfer (CHT) studies are carried out to imitate experimental studies for heat transfer measurement in hypersonic flow regime. The finite volume based solvers are used for analyzing the heat interaction between fluid and solid domains. Temperature and surface heat flux signals are predicted by both coupled and decoupled CHT analysis techniques for hypersonic Mach numbers. These two methodologies are also used to study the effect of different wall materials on surface parameters. Effectiveness of these CHT solvers has been verified for the inverse problem of wall heat flux recovery using various techniques reported in the literature. Both coupled and decoupled CHT techniques are seen to be equally useful for prediction of local temperature and heat flux signals prior to the experiments in hypersonic flows.

CFD on hypersonic flow geometries with aeroheating

Science.gov (United States)

Sohail, Muhammad Amjad; Chao, Yan; Hui, Zhang Hui; Ullah, Rizwan

2012-11-01

The hypersonic flowfield around a blunted cone and cone-flare exhibits some of the major features of the flows around space vehicles, e.g. a detached bow shock in the stagnation region and the oblique shock wave/boundary layer interaction at the cone-flare junction. The shock wave/boundary layer interaction can produce a region of separated flow. This phenomenon may occur, for example, at the upstream-facing corner formed by a deflected control surface on a hypersonic entry vehicle, where the length of separation has implications for control effectiveness. Computational fluid-dynamics results are presented to show the flowfield around a blunted cone and cone-flare configurations in hypersonic flow with separation. This problem is of particular interest since it features most of the aspects of the hypersonic flow around planetary entry vehicles. The region between the cone and the flare is particularly critical with respect to the evaluation of the surface pressure and heat flux with aeroheating. Indeed, flow separation is induced by the shock wave boundary layer interaction, with subsequent flow reattachment, that can dramatically enhance the surface heat transfer. The exact determination of the extension of the recirculation zone is a particularly delicate task for numerical codes. Laminar flow and turbulent computations have been carried out using a full Navier-Stokes solver, with freestream conditions provided by the experimental data obtained at Mach 6, 8, and 16.34 wind tunnel. The numerical results are compared with the measured pressure and surface heat flux distributions in the wind tunnel and a good agreement is found, especially on the length of the recirculation region and location of shock waves. The critical physics of entropy layer, boundary layers, boundary layers and shock wave interaction and flow behind shock are properly captured and elaborated.. Hypersonic flows are characterized by high Mach number and high total enthalpy. An elevated

Hypersonic Tunnel Facility (HTF)

Data.gov (United States)

Federal Laboratory Consortium — The Hypersonic Tunnel Facility (HTF) is a blow-down, non-vitiated (clean air) free-jet wind tunnel capable of testing large-scale, propulsion systems at Mach 5, 6,...

K-distribution models for gas mixtures in hypersonic nonequilibrium flows

Science.gov (United States)

Bansal, Ankit

Calculation of nonequilibrium radiation field in plasmas around a spacecraft entering into an atmosphere at hypersonic velocities is a very complicated and computationally expensive task. The objective of this Dissertation is to collect state-of-the art spectroscopic data for the evaluation of spectral absorption and emission coefficients of atomic and molecular gases, develop efficient and accurate spectral models and databases, and study the effect of radiation on wall heat loads and flowfield around the spacecraft. The most accurate simulation of radiative transport in the shock layer requires calculating the gas properties at a large number of wavelengths and solving the Radiative Transfer Equation (RTE) in a line-by-line (LBL) fashion, which is prohibitively expensive for coupled simulations. A number of k-distribution based spectral models are developed for atomic lines, continuum and molecular bands that allow efficient evaluation of radiative properties and heat loads in hypersonic shock layer plasma. Molecular radiation poses very different challenges than atomic radiation. A molecular spectrum is governed by simultaneous electronic, vibrational and rotational transitions, making the spectrum very strongly dependent on wavelength. In contrast to an atomic spectrum, where line wings play a major role in heat transfer, most of the heat transfer in molecular spectra occurs near line centers. As the first step, k-distribution models are developed separately for atomic and molecular species, taking advantage of the fact that in the Earth's atmosphere the radiative field is dominated by atomic species (N and O) and in Titan's and Mars' atmospheres molecular bands of CN and CO are dominant. There are a number of practical applications where both atomic and molecular species are present, for example, the vacuum-ultra-violet spectrum during Earth's reentry conditions is marked by emission from atomic bound-bound lines and continuum and simultaneous absorption by

Hypersonic modes in nanophononic semiconductors.

Science.gov (United States)

Hepplestone, S P; Srivastava, G P

2008-09-05

Frequency gaps and negative group velocities of hypersonic phonon modes in periodically arranged composite semiconductors are presented. Trends and criteria for phononic gaps are discussed using a variety of atomic-level theoretical approaches. From our calculations, the possibility of achieving semiconductor-based one-dimensional phononic structures is established. We present results of the location and size of gaps, as well as negative group velocities of phonon modes in such structures. In addition to reproducing the results of recent measurements of the locations of the band gaps in the nanosized Si/Si{0.4}Ge{0.6} superlattice, we show that such a system is a true one-dimensional hypersonic phononic crystal.

Experimental Investigation of Brazilian 14-X B Hypersonic Scramjet Aerospace Vehicle

Directory of Open Access Journals (Sweden)

João Felipe de Araujo Martos

2017-01-01

Full Text Available The Brazilian hypersonic scramjet aerospace vehicle 14-X B is a technological demonstrator of a hypersonic airbreathing propulsion system based on the supersonic combustion (scramjet to be tested in flight into the Earth’s atmosphere at an altitude of 30 km and Mach number 7. The 14-X B has been designed at the Prof. Henry T. Nagamatsu Laboratory of Aerothermodynamics and Hypersonics, Institute for Advanced Studies (IEAv, Brazil. The IEAv T3 Hypersonic Shock Tunnel is a ground-test facility able to produce high Mach number and high enthalpy flows in the test section close to those encountered during the flight of the 14-X B into the Earth’s atmosphere at hypersonic flight speeds. A 1 m long stainless steel 14-X B model was experimentally investigated at T3 Hypersonic Shock Tunnel, for freestream Mach numbers ranging from 7 to 8. Static pressure measurements along the lower surface of the 14-X B, as well as high-speed Schlieren photographs taken from the 5.5° leading edge and the 14.5° deflection compression ramp, provided experimental data. Experimental data was compared to the analytical theoretical solutions and the computational fluid dynamics (CFD simulations, showing good qualitative agreement and in consequence demonstrating the importance of these methods in the project of the 14-X B hypersonic scramjet aerospace vehicle.

Production of radiatively cooled hypersonic plasma jets and links to astrophysical jets

International Nuclear Information System (INIS)

Lebedev, S V; Ciardi, A; Ampleford, D J; Bland, S N; Bott, S C; Chittenden, J P; Hall, G N; Rapley, J; Jennings, C; Sherlock, M; Frank, A; Blackman, E G

2005-01-01

We present results of high energy density laboratory experiments on the production of supersonic radiatively cooled plasma jets with dimensionless parameters (Mach number ∼30, cooling parameter ∼1 and density contrast ρ j /ρ a ∼ 10) similar to those in young stellar objects jets. The jets are produced using two modifications of wire array Z-pinch driven by 1 MA, 250 ns current pulse of MAGPIE facility at Imperial College, London. In the first set of experiments the produced jets are purely hydrodynamic and are used to study deflection of the jets by the plasma cross-wind, including the structure of internal oblique shocks in the jets. In the second configuration the jets are driven by the pressure of the toroidal magnetic field and this configuration is relevant to the astrophysical models of jet launching mechanisms. Modifications of the experimental configuration allowing the addition of the poloidal magnetic field and angular momentum to the jets are also discussed. We also present three-dimensional resistive magneto-hydrodynamic simulations of the experiments and discuss the scaling of the experiments to the astrophysical systems

Radiation reaction effect on laser driven auto-resonant particle acceleration

International Nuclear Information System (INIS)

Sagar, Vikram; Sengupta, Sudip; Kaw, P. K.

2015-01-01

The effects of radiation reaction force on laser driven auto-resonant particle acceleration scheme are studied using Landau-Lifshitz equation of motion. These studies are carried out for both linear and circularly polarized laser fields in the presence of static axial magnetic field. From the parametric study, a radiation reaction dominated region has been identified in which the particle dynamics is greatly effected by this force. In the radiation reaction dominated region, the two significant effects on particle dynamics are seen, viz., (1) saturation in energy gain by the initially resonant particle and (2) net energy gain by an initially non-resonant particle which is caused due to resonance broadening. It has been further shown that with the relaxation of resonance condition and with optimum choice of parameters, this scheme may become competitive with the other present-day laser driven particle acceleration schemes. The quantum corrections to the Landau-Lifshitz equation of motion have also been taken into account. The difference in the energy gain estimates of the particle by the quantum corrected and classical Landau-Lifshitz equation is found to be insignificant for the present day as well as upcoming laser facilities

Data driven modelling of vertical atmospheric radiation

International Nuclear Information System (INIS)

Antoch, Jaromir; Hlubinka, Daniel

2011-01-01

In the Czech Hydrometeorological Institute (CHMI) there exists a unique set of meteorological measurements consisting of the values of vertical atmospheric levels of beta and gamma radiation. In this paper a stochastic data-driven model based on nonlinear regression and on nonhomogeneous Poisson process is suggested. In the first part of the paper, growth curves were used to establish an appropriate nonlinear regression model. For comparison we considered a nonhomogeneous Poisson process with its intensity based on growth curves. In the second part both approaches were applied to the real data and compared. Computational aspects are briefly discussed as well. The primary goal of this paper is to present an improved understanding of the distribution of environmental radiation as obtained from the measurements of the vertical radioactivity profiles by the radioactivity sonde system. - Highlights: → We model vertical atmospheric levels of beta and gamma radiation. → We suggest appropriate nonlinear regression model based on growth curves. → We compare nonlinear regression modelling with Poisson process based modeling. → We apply both models to the real data.

Emission of electromagnetic radiation from beam driven plasmas

International Nuclear Information System (INIS)

Newman, D.L.

1985-01-01

Two production mechanisms for electromagnetic radiation from a plasma containing electron-beam-driven weak Langmuir turbulence are studied: induced Compton conversion and two-Langmuir-wave coalescence. Induced Compton conversion in which a Langmuir wave scatters off a relativistic electron while converting into a transversely polarized electromagnetic wave is considered as a means for producing amplified electromagnetic radiation from a beam-plasma system at frequencies well above the electron plasma frequency. The induced emission growth rates of the radiation produced by a monoenergetic ultrarelativistic electron beam are determined as a function of the Langmuir turbulence spectrum in the background plasma and are numerically evaluated for a range of model Langmuir spectra. Induced Compton conversion can play a role in emission from astrophysical beam-plasma systems if the electron beam is highly relativistic and sufficiently narrow. However, it is found that the growth rates for this process are too small in all cases studied to account for the intense high-frequency radiation observed in laboratory experiments. Two-Langmuir-wave coalescence as a means of producing radiation at 2omega/sub p/ is investigated in the setting of the earth's foreshock

Development of an aerodynamic measurement system for hypersonic rarefied flows.

Science.gov (United States)

Ozawa, T; Fujita, K; Suzuki, T

2015-01-01

A hypersonic rarefied wind tunnel (HRWT) has lately been developed at Japan Aerospace Exploration Agency in order to improve the prediction of rarefied aerodynamics. Flow characteristics of hypersonic rarefied flows have been investigated experimentally and numerically. By conducting dynamic pressure measurements with pendulous models and pitot pressure measurements, we have probed flow characteristics in the test section. We have also improved understandings of hypersonic rarefied flows by integrating a numerical approach with the HRWT measurement. The development of the integration scheme between HRWT and numerical approach enables us to estimate the hypersonic rarefied flow characteristics as well as the direct measurement of rarefied aerodynamics. Consequently, this wind tunnel is capable of generating 25 mm-core flows with the free stream Mach number greater than 10 and Knudsen number greater than 0.1.

Design of adaptive switching control for hypersonic aircraft

Directory of Open Access Journals (Sweden)

Xin Jiao

2015-10-01

Full Text Available This article proposes a novel adaptive switching control of hypersonic aircraft based on type-2 Takagi–Sugeno–Kang fuzzy sliding mode control and focuses on the problem of stability and smoothness in the switching process. This method uses full-state feedback to linearize the nonlinear model of hypersonic aircraft. Combining the interval type-2 Takagi–Sugeno–Kang fuzzy approach with sliding mode control keeps the adaptive switching process stable and smooth. For rapid stabilization of the system, the adaptive laws use a direct constructive Lyapunov analysis together with an established type-2 Takagi–Sugeno–Kang fuzzy logic system. Simulation results indicate that the proposed control scheme can maintain the stability and smoothness of switching process for the hypersonic aircraft.

Issues Associated with a Hypersonic Maglev Sled

Science.gov (United States)

Haney, Joseph W.; Lenzo, J.

1996-01-01

Magnetic levitation has been explored for application from motors to transportation. All of these applications have been at velocities where the physics of the air or operating fluids are fairly well known. Application of Maglev to hypersonic velocities (Mach greater than 5) presents many opportunities, but also issues that require understanding and resolution. Use of Maglev to upgrade the High Speed Test Track at Holloman Air Force Base in Alamogordo New Mexico is an actual hypersonic application that provides the opportunity to improve test capabilities. However, there are several design issues that require investigation. This paper presents an overview of the application of Maglev to the test track and the issues associated with developing a hypersonic Maglev sled. The focus of this paper is to address the issues with the Maglev sled design, rather than the issues with the development of superconducting magnets of the sled system.

Hypersonic Inflatable Aerodynamic Decelerator (HIAD)

Data.gov (United States)

National Aeronautics and Space Administration — Develop an entry and descent technology to enhance and enable robotic and scientific missions to destinations with atmospheres.The Hypersonic Inflatable Aerodynamic...

Progress in modeling hypersonic turbulent boundary layers

Science.gov (United States)

Zeman, Otto

1993-01-01

A good knowledge of the turbulence structure, wall heat transfer, and friction in turbulent boundary layers (TBL) at high speeds is required for the design of hypersonic air breathing airplanes and reentry space vehicles. This work reports on recent progress in the modeling of high speed TBL flows. The specific research goal described here is the development of a second order closure model for zero pressure gradient TBL's for the range of Mach numbers up to hypersonic speeds with arbitrary wall cooling requirements.

RADIATION-DRIVEN IMPLOSION AND TRIGGERED STAR FORMATION

International Nuclear Information System (INIS)

Bisbas, Thomas G.; Wuensch, Richard; Whitworth, Anthony P.; Walch, Stefanie; Hubber, David A.

2011-01-01

We present simulations of initially stable isothermal clouds exposed to ionizing radiation from a discrete external source, and identify the conditions that lead to radiatively driven implosion and star formation. We use the smoothed particle hydrodynamics code SEREN and a HEALPix-based photoionization algorithm to simulate the propagation of the ionizing radiation and the resulting dynamical evolution of the cloud. We find that the incident ionizing flux, Φ LyC , is the critical parameter determining the cloud evolution. At moderate fluxes, a large fraction of the cloud mass is converted into stars. As the flux is increased, the fraction of the cloud mass that is converted into stars and the mean masses of the individual stars both decrease. Very high fluxes simply disperse the cloud. Newly formed stars tend to be concentrated along the central axis of the cloud (i.e., the axis pointing in the direction of the incident flux). For given cloud parameters, the time, t * , at which star formation starts is proportional to Φ -1/3 LyC . The pattern of star formation found in the simulations is similar to that observed in bright-rimmed clouds.

Three-Dimensional Aeroelastic and Aerothermoelastic Behavior in Hypersonic Flow

Science.gov (United States)

McNamara, Jack J.; Friedmann, Peretz P.; Powell, Kenneth G.; Thuruthimattam, Biju J.; Bartels, Robert E.

2005-01-01

The aeroelastic and aerothermoelastic behavior of three-dimensional configurations in hypersonic flow regime are studied. The aeroelastic behavior of a low aspect ratio wing, representative of a fin or control surface on a generic hypersonic vehicle, is examined using third order piston theory, Euler and Navier-Stokes aerodynamics. The sensitivity of the aeroelastic behavior generated using Euler and Navier-Stokes aerodynamics to parameters governing temporal accuracy is also examined. Also, a refined aerothermoelastic model, which incorporates the heat transfer between the fluid and structure using CFD generated aerodynamic heating, is used to examine the aerothermoelastic behavior of the low aspect ratio wing in the hypersonic regime. Finally, the hypersonic aeroelastic behavior of a generic hypersonic vehicle with a lifting-body type fuselage and canted fins is studied using piston theory and Euler aerodynamics for the range of 2.5 less than or equal to M less than or equal to 28, at altitudes ranging from 10,000 feet to 80,000 feet. This analysis includes a study on optimal mesh selection for use with Euler aerodynamics. In addition to the aeroelastic and aerothermoelastic results presented, three time domain flutter identification techniques are compared, namely the moving block approach, the least squares curve fitting method, and a system identification technique using an Auto-Regressive model of the aeroelastic system. In general, the three methods agree well. The system identification technique, however, provided quick damping and frequency estimations with minimal response record length, and therefore o ers significant reductions in computational cost. In the present case, the computational cost was reduced by 75%. The aeroelastic and aerothermoelastic results presented illustrate the applicability of the CFL3D code for the hypersonic flight regime.

High quality ceramic coatings sprayed by high efficiency hypersonic plasma spraying gun

International Nuclear Information System (INIS)

Zhu Sheng; Xu Binshi; Yao JiuKun

2005-01-01

This paper introduced the structure of the high efficiency hypersonic plasma spraying gun and the effects of hypersonic plasma jet on the sprayed particles. The optimised spraying process parameters for several ceramic powders such as Al 2 O 3 , Cr 2 O 3 , ZrO 2 , Cr 3 C 2 and Co-WC were listed. The properties and microstructure of the sprayed ceramic coatings were investigated. Nano Al 2 O 3 -TiO 2 ceramic coating sprayed by using the high efficiency hypersonic plasma spraying was also studied. Compared with the conventional air plasma spraying, high efficiency hypersonic plasma spraying improves greatly the ceramic coatings quality but at low cost. (orig.)

Winds from accretion disks driven by the radiation and magnetocentrifugal force

OpenAIRE

Proga, D.

2000-01-01

We study the 2-D, time-dependent hydrodynamics of radiation-driven winds from luminous accretion disks threaded by a strong, large-scale, ordered magnetic field. The radiation force is due to spectral lines and is calculated using a generalized multidimensional formulation of the Sobolev approximation. The effects of the magnetic field are approximated by adding a force that emulates a magnetocentrifugal force. Our approach allows us to calculate disk winds when the magnetic field controls th...

Pitot pressure analyses in CO2 condensing rarefied hypersonic flows

Science.gov (United States)

Ozawa, T.; Suzuki, T.; Fujita, K.

2016-11-01

In order to improve the accuracy of rarefied aerodynamic prediction, a hypersonic rarefied wind tunnel (HRWT) was developed at Japan Aerospace Exploration Agency. While this wind tunnel has been limited to inert gases, such as nitrogen or argon, we recently extended the capability of HRWT to CO2 hypersonic flows for several Mars missions. Compared to our previous N2 cases, the condensation effect may not be negligible for CO2 rarefied aerodynamic measurements. Thus, in this work, we have utilized both experimental and numerical approaches to investigate the condensation and rarefaction effects in CO2 hypersonic nozzle flows.

Hypersonic drift-tearing magnetic islands in tokamak plasmas

International Nuclear Information System (INIS)

Fitzpatrick, R.; Waelbroeck, F. L.

2007-01-01

A two-fluid theory of long wavelength, hypersonic, drift-tearing magnetic islands in low-collisionality, low-β plasmas possessing relatively weak magnetic shear is developed. The model assumes both slab geometry and cold ions, and neglects electron temperature and equilibrium current gradient effects. The problem is solved in three asymptotically matched regions. The 'inner region' contains the island. However, the island emits electrostatic drift-acoustic waves that propagate into the surrounding 'intermediate region', where they are absorbed by the plasma. Since the waves carry momentum, the inner region exerts a net force on the intermediate region, and vice versa, giving rise to strong velocity shear in the region immediately surrounding the island. The intermediate region is matched to the surrounding 'outer region', in which ideal magnetohydrodynamic holds. Isolated hypersonic islands propagate with a velocity that lies between those of the unperturbed local ion and electron fluids, but is much closer to the latter. The ion polarization current is stabilizing, and increases with increasing island width. Finally, the hypersonic branch of isolated island solutions ceases to exist above a certain critical island width. Hypersonic islands whose widths exceed the critical width are hypothesized to bifurcate to the so-called 'sonic' solution branch

Galactic Winds Driven by Supernovae and Radiation Pressure: Theory and Simulations

Science.gov (United States)

Zhang, Dong; Davis, Shane

2018-01-01

Galactic winds are ubiquitous in most rapidly star-forming galaxies. They are crucial to the process of galaxy formation and evolution, regulating star formation, shaping the stellar mass function and the mass-metallicity relation, and enriching the intergalactic medium with metals. Although important, the physics of galactic winds is still unclear. Winds may be driven by many mechanisms including overlapping supernovae explosions, radiation pressure of starlight on dust grains, and cosmic rays. However, the growing observations of multiphase structure in galactic winds in a large number of galaxies have not been well explained by any models. In this talk I will focus on the models of supernova- and radiation-pressure-driven winds. Using the state-of-the-art numerical simulations, I will assess the relative merits of these driving mechanisms for accelerating cold and warm clouds to observed velocities, and momentum flux boost during wind propagation.

Heating Augmentation for Short Hypersonic Protuberances

Science.gov (United States)

Mazaheri, Ali R.; Wood, William A.

2008-01-01

Computational aeroheating analyses of the Space Shuttle Orbiter plug repair models are validated against data collected in the Calspan University of Buffalo Research Center (CUBRC) 48 inch shock tunnel. The comparison shows that the average difference between computed heat transfer results and the data is about 9.5%. Using CFD and Wind Tunnel (WT) data, an empirical correlation for estimating heating augmentation on short hypersonic protuberances (k/delta less than 0.3) is proposed. This proposed correlation is compared with several computed flight simulation cases and good agreement is achieved. Accordingly, this correlation is proposed for further investigation on other short hypersonic protuberances for estimating heating augmentation.

Hypersonic drone vehicle design: A multidisciplinary experience

Science.gov (United States)

1988-01-01

UCLA's Advanced Aeronautic Design group focussed their efforts on design problems of an unmanned hypersonic vehicle. It is felt that a scaled hypersonic drone is necesary to bridge the gap between present theory on hypersonics and the future reality of the National Aerospace Plane (NASP) for two reasons: (1) to fulfill a need for experimental data in the hypersonic regime, and (2) to provide a testbed for the scramjet engine which is to be the primary mode of propulsion for the NASP. The group concentrated on three areas of great concern to NASP design: propulsion, thermal management, and flight systems. Problem solving in these areas was directed toward design of the drone with the idea that the same design techniques could be applied to the NASP. A 70 deg swept double-delta wing configuration, developed in the 70's at the NASA Langley, was chosen as the aerodynamic and geometric model for the drone. This vehicle would be air launched from a B-1 at Mach 0.8 and 48,000 feet, rocket boosted by two internal engines to Mach 10 and 100,000 feet, and allowed to cruise under power of the scramjet engine until burnout. It would then return to base for an unpowered landing. Preliminary energy calculations based on flight requirements give the drone a gross launch weight of 134,000 pounds and an overall length of 85 feet.

CFD for hypersonic propulsion

Science.gov (United States)

Povinelli, Louis A.

1991-01-01

An overview is given of research activity on the application of computational fluid dynamics (CDF) for hypersonic propulsion systems. After the initial consideration of the highly integrated nature of air-breathing hypersonic engines and airframe, attention is directed toward computations carried out for the components of the engine. A generic inlet configuration is considered in order to demonstrate the highly three dimensional viscous flow behavior occurring within rectangular inlets. Reacting flow computations for simple jet injection as well as for more complex combustion chambers are then discussed in order to show the capability of viscous finite rate chemical reaction computer simulations. Finally, the nozzle flow fields are demonstrated, showing the existence of complex shear layers and shock structure in the exhaust plume. The general issues associated with code validation as well as the specific issue associated with the use of CFD for design are discussed. A prognosis for the success of CFD in the design of future propulsion systems is offered.

Uncertainty Propagation in Hypersonic Vehicle Aerothermoelastic Analysis

Science.gov (United States)

Lamorte, Nicolas Etienne

Hypersonic vehicles face a challenging flight environment. The aerothermoelastic analysis of its components requires numerous simplifying approximations. Identifying and quantifying the effect of uncertainties pushes the limits of the existing deterministic models, and is pursued in this work. An uncertainty quantification framework is used to propagate the effects of identified uncertainties on the stability margins and performance of the different systems considered. First, the aeroelastic stability of a typical section representative of a control surface on a hypersonic vehicle is examined. Variability in the uncoupled natural frequencies of the system is modeled to mimic the effect of aerodynamic heating. Next, the stability of an aerodynamically heated panel representing a component of the skin of a generic hypersonic vehicle is considered. Uncertainty in the location of transition from laminar to turbulent flow and the heat flux prediction is quantified using CFD. In both cases significant reductions of the stability margins are observed. A loosely coupled airframe--integrated scramjet engine is considered next. The elongated body and cowl of the engine flow path are subject to harsh aerothermodynamic loading which causes it to deform. Uncertainty associated with deformation prediction is propagated to the engine performance analysis. The cowl deformation is the main contributor to the sensitivity of the propulsion system performance. Finally, a framework for aerothermoelastic stability boundary calculation for hypersonic vehicles using CFD is developed. The usage of CFD enables one to consider different turbulence conditions, laminar or turbulent, and different models of the air mixture, in particular real gas model which accounts for dissociation of molecules at high temperature. The system is found to be sensitive to turbulence modeling as well as the location of the transition from laminar to turbulent flow. Real gas effects play a minor role in the

Hypersonic Control Modeling and Simulation Tool for Lifting Towed Ballutes, Phase I

Data.gov (United States)

National Aeronautics and Space Administration — Global Aerospace Corporation proposes to develop a hypersonic control modeling and simulation tool for hypersonic aeroassist vehicles. Our control and simulation...

Guidance Law and Neural Control for Hypersonic Missile to Track Targets

Directory of Open Access Journals (Sweden)

Wenxing Fu

2016-01-01

Full Text Available Hypersonic technology plays an important role in prompt global strike. Because the flight dynamics of a hypersonic vehicle is nonlinear, uncertain, and highly coupled, the controller design is challenging, especially to design its guidance and control law during the attack of a maneuvering target. In this paper, the sliding mode control (SMC method is used to develop the guidance law from which the desired flight path angle is derived. With the desired information as control command, the adaptive neural control in discrete time is investigated ingeniously for the longitudinal dynamics of the hypersonic missile. The proposed guidance and control laws are validated by simulation of a hypersonic missile against a maneuvering target. It is demonstrated that the scheme has good robustness and high accuracy to attack a maneuvering target in the presence of external disturbance and missile model uncertainty.

High-speed Imaging of Global Surface Temperature Distributions on Hypersonic Ballistic-Range Projectiles

Science.gov (United States)

Wilder, Michael C.; Reda, Daniel C.

2004-01-01

times as short as 2 ns. The infrared camera uses an Indium Antimonide (InSb) sensor in the 3 to 5 micron band and is capable of integration times as short as 500 ns. The projectiles are imaged nearly head-on using expendable mirrors offset slightly from the flight path. The proposed paper will discuss the application of high-speed digital imaging systems in the NASA-Ames hypersonic ballistic range, and the challenges encountered when applying these systems. Example images of the thermal radiation from the blunt nose of projectiles flying at nearly 14 times the speed of sound will be given.

CFD analysis of hypersonic, chemically reacting flow fields

Science.gov (United States)

Edwards, T. A.

1993-01-01

Design studies are underway for a variety of hypersonic flight vehicles. The National Aero-Space Plane will provide a reusable, single-stage-to-orbit capability for routine access to low earth orbit. Flight-capable satellites will dip into the atmosphere to maneuver to new orbits, while planetary probes will decelerate at their destination by atmospheric aerobraking. To supplement limited experimental capabilities in the hypersonic regime, computational fluid dynamics (CFD) is being used to analyze the flow about these configurations. The governing equations include fluid dynamic as well as chemical species equations, which are being solved with new, robust numerical algorithms. Examples of CFD applications to hypersonic vehicles suggest an important role this technology will play in the development of future aerospace systems. The computational resources needed to obtain solutions are large, but solution adaptive grids, convergence acceleration, and parallel processing may make run times manageable.

Lateral control strategy for a hypersonic cruise missile

Directory of Open Access Journals (Sweden)

Yonghua Fan

2017-04-01

Full Text Available Hypersonic cruise missile always adopts the configuration of waverider body with the restraint of scramjet. As a result, the lateral motion exhibits serious coupling, and the controller design of the lateral lateral system cannot be conducted separately for yaw channel and roll channel. A multiple input and multiple output optimal control method with integrators is presented to design the lateral combined control system for hypersonic cruise missile. A hypersonic cruise missile lateral model is linearized as a multiple input and multiple output plant, which is coupled by kinematics and fin deflection between yaw and roll. In lateral combined controller, the integrators are augmented, respectively, into the loop of roll angle and lateral overload to ensure that the commands are tracked with zero steady-state error. Through simulation, the proposed controller demonstrates good performance in tracking the command of roll angle and lateral overload.

Hypersonic expansion of the Fokker--Planck equation

International Nuclear Information System (INIS)

Fernandez-Feria, R.

1989-01-01

A systematic study of the hypersonic limit of a heavy species diluted in a much lighter gas is made via the Fokker--Planck equation governing its velocity distribution function. In particular, two different hypersonic expansions of the Fokker--Planck equation are considered, differing from each other in the momentum equation of the heavy gas used as the basis of the expansion: in the first of them, the pressure tensor is neglected in that equation while, in the second expansion, the pressure tensor term is retained. The expansions are valid when the light gas Mach number is O(1) or larger and the difference between the mean velocities of light and heavy components is small compared to the light gas thermal speed. They can be applied away from regions where the spatial gradient of the distribution function is very large, but it is not restricted with respect to the temporal derivative of the distribution function. The hydrodynamic equations corresponding to the lowest order of both expansions constitute two different hypersonic closures of the moment equations. For the subsequent orders in the expansions, closed sets of moment equations (hydrodynamic equations) are given. Special emphasis is made on the order of magnitude of the errors of the lowest-order hydrodynamic quantities. It is shown that if the heat flux vanishes initially, these errors are smaller than one might have expected from the ordinary scaling of the hypersonic closure. Also it is found that the normal solution of both expansions is a Gaussian distribution at the lowest order

Effect of Dielectric Barrier Discharge Plasma Actuators on Non-equilibrium Hypersonic Flows

Science.gov (United States)

2014-10-28

results for MIG with the US3D code devel- oped at the University of Minnesota.61 US3D is an unstruc- tured CFD code for hypersonic flow solution used...Effect of dielectric barrier discharge plasma actuators on non-equilibrium hypersonic flows Ankush Bhatia,1 Subrata Roy,1 and Ryan Gosse2 1Applied...a cylindrical body in Mach 17 hypersonic flow is presented. This application focuses on using sinusoidal dielectric barrier discharge plasma actuators

A weakly coupled semiconductor superlattice as a harmonic hypersonic-electrical transducer

International Nuclear Information System (INIS)

Poyser, C L; Akimov, A V; Campion, R P; Kent, A J; Balanov, A G

2015-01-01

We study experimentally and theoretically the effects of high-frequency strain pulse trains on the charge transport in a weakly coupled semiconductor superlattice. In a frequency range of the order of 100 GHz such excitation may be considered as single harmonic hypersonic excitation. While travelling along the axis of the SL, the hypersonic acoustic wavepacket affects the electron tunnelling, and thus governs the electrical current through the device. We reveal how the change of current depends on the parameters of the hypersonic excitation and on the bias applied to the superlattice. We have found that the changes in the transport properties of the superlattices caused by the acoustic excitation can be largely explained using the current–voltage relation of the unperturbed system. Our experimental measurements show multiple peaks in the dependence of the transferred charge on the repetition rate of the strain pulses in the train. We demonstrate that these resonances can be understood in terms of the spectrum of the applied acoustic perturbation after taking into account the multiple reflections in the metal film serving as a generator of hypersonic excitation. Our findings suggest an application of the semiconductor superlattice as a hypersonic-electrical transducer, which can be used in various microwave devices. (paper)

The energetics of AGN radiation pressure-driven outflows

Science.gov (United States)

Ishibashi, W.; Fabian, A. C.; Maiolino, R.

2018-05-01

The increasing observational evidence of galactic outflows is considered as a sign of active galactic nucleus (AGN) feedback in action. However, the physical mechanism responsible for driving the observed outflows remains unclear, and whether it is due to momentum, energy, or radiation is still a matter of debate. The observed outflow energetics, in particular the large measured values of the momentum ratio (\\dot{p}/(L/c) ˜ 10) and energy ratio (\\dot{E}_k/L ˜ 0.05), seems to favour the energy-driving mechanism; and most observational works have focused their comparison with wind energy-driven models. Here, we show that AGN radiation pressure on dust can adequately reproduce the observed outflow energetics (mass outflow rate, momentum flux, and kinetic power), as well as the scalings with luminosity, provided that the effects of radiation trapping are properly taken into account. In particular, we predict a sublinear scaling for the mass outflow rate (\\dot{M} ∝ L^{1/2}) and a superlinear scaling for the kinetic power (\\dot{E}_k ∝ L^{3/2}), in agreement with the observational scaling relations reported in the most recent compilation of AGN outflow data. We conclude that AGN radiative feedback can account for the global outflow energetics, at least equally well as the wind energy-driving mechanism, and therefore both physical models should be considered in the interpretation of future AGN outflow observations.

Supersonic Combustion in Air-Breathing Propulsion Systems for Hypersonic Flight

Science.gov (United States)

Urzay, Javier

2018-01-01

Great efforts have been dedicated during the last decades to the research and development of hypersonic aircrafts that can fly at several times the speed of sound. These aerospace vehicles have revolutionary applications in national security as advanced hypersonic weapons, in space exploration as reusable stages for access to low Earth orbit, and in commercial aviation as fast long-range methods for air transportation of passengers around the globe. This review addresses the topic of supersonic combustion, which represents the central physical process that enables scramjet hypersonic propulsion systems to accelerate aircrafts to ultra-high speeds. The description focuses on recent experimental flights and ground-based research programs and highlights associated fundamental flow physics, subgrid-scale model development, and full-system numerical simulations.

Hypersonic flow past slender bodies in dispersive hydrodynamics

International Nuclear Information System (INIS)

El, G.A.; Khodorovskii, V.V.; Tyurina, A.V.

2004-01-01

The problem of two-dimensional steady hypersonic flow past a slender body is formulated for dispersive media. It is shown that for the hypersonic flow, the original 2+0 boundary-value problem is asymptotically equivalent to the 1+1 piston problem for the fully nonlinear flow in the same physical system, which allows one to take advantage of the analytic methods developed for one-dimensional systems. This type of equivalence, well known in ideal Euler gas dynamics, has not been established for dispersive hydrodynamics so far. Two examples pertaining to collisionless plasma dynamics are considered

The theory of radiation driven stellar winds and the Wolf-Rayet phenomenon

International Nuclear Information System (INIS)

Abbott, D.C.

1982-01-01

The author considers the question of whether the mass loss observed from Wolf-Rayet stars can be explained by a version of wind theory which is scaled to the conditions found in the envelopes of Wolf-Rayet stars. He discusses the following topics: - The calculated radiation pressure in OB stars, and its dependence on temperature, density, and chemical composition. - A comparison between predicted and observed mass loss rates and terminal velocities for OB stars. - The applicability of the standard radiation driven wind models to Wolf-Rayet stars. - Speculations on how Wolf-Rayet stars achieve their enormous mass loss rates within the context of the radiation pressure mechanism. (Auth.)

Direct Numerical Simulation of Acoustic Noise Generation from the Nozzle Wall of a Hypersonic Wind Tunnel

Science.gov (United States)

Huang, Junji; Duan, Lian; Choudhari, Meelan M.

2017-01-01

The acoustic radiation from the turbulent boundary layer on the nozzle wall of a Mach 6 Ludwieg Tube is simulated using Direct Numerical Simulations (DNS), with the flow conditions falling within the operational range of the Mach 6 Hypersonic Ludwieg Tube, Braunschweig (HLB). The mean and turbulence statistics of the nozzle-wall boundary layer show good agreement with those predicted by Pate's correlation and Reynolds Averaged Navier-Stokes (RANS) computations. The rms pressure fluctuation P'(rms)/T(w) plateaus in the freestream core of the nozzle. The intensity of the freestream noise within the nozzle is approximately 20% higher than that radiated from a single at pate with a similar freestream Mach number, potentially because of the contributions to the acoustic radiation from multiple azimuthal segments of the nozzle wall.

Classifier utility modeling and analysis of hypersonic inlet start/unstart considering training data costs

Science.gov (United States)

Chang, Juntao; Hu, Qinghua; Yu, Daren; Bao, Wen

2011-11-01

Start/unstart detection is one of the most important issues of hypersonic inlets and is also the foundation of protection control of scramjet. The inlet start/unstart detection can be attributed to a standard pattern classification problem, and the training sample costs have to be considered for the classifier modeling as the CFD numerical simulations and wind tunnel experiments of hypersonic inlets both cost time and money. To solve this problem, the CFD simulation of inlet is studied at first step, and the simulation results could provide the training data for pattern classification of hypersonic inlet start/unstart. Then the classifier modeling technology and maximum classifier utility theories are introduced to analyze the effect of training data cost on classifier utility. In conclusion, it is useful to introduce support vector machine algorithms to acquire the classifier model of hypersonic inlet start/unstart, and the minimum total cost of hypersonic inlet start/unstart classifier can be obtained by the maximum classifier utility theories.

A computational study of inviscid hypersonic flows using energy relaxation method

International Nuclear Information System (INIS)

Nagdewe, Suryakant; Kim, H. D.; Shevare, G. R.

2008-01-01

Reasonable analysis of hypersonic flows requires a thermodynamic non-equilibrium model to properly simulate strong shock waves or high pressure and temperature states in the flow field. The energy relaxation method (ERM) has been used to model such a non-equilibrium effect which is generally expressed as a hyperbolic system of equations with a stiff relaxation source term. Relaxation time that is multiplied with source terms is responsible for nonequilibrium in the system. In the present study, a numerical analysis has been carried out with varying values of relaxation time for several hypersonic flows with AUSM (advection upstream splitting method) as a numerical scheme. Vibration modes of thermodynamic nonequilibrium effects are considered. The results obtained showed that, as the relaxation time reduces to zero, the solution marches toward equilibrium, while it shows non-equilibrium effects, as the relaxation time increases. The present computations predicted the experiment results of hypersonic flows with good accuracy. The work carried out suggests that the present energy relaxation method can be robust for analysis of hypersonic flows

Multi-Exciter Vibroacoustic Simulation of Hypersonic Flight Vibration

International Nuclear Information System (INIS)

GREGORY, DANNY LYNN; CAP, JEROME S.; TOGAMI, THOMAS C.; NUSSER, MICHAEL A.; HOLLINGSHEAD, JAMES RONALD

1999-01-01

Many aerospace structures must survive severe high frequency, hypersonic, random vibration during their flights. The random vibrations are generated by the turbulent boundary layer developed along the exterior of the structures during flight. These environments have not been simulated very well in the past using a fixed-based, single exciter input with an upper frequency range of 2 kHz. This study investigates the possibility of using acoustic ardor independently controlled multiple exciters to more accurately simulate hypersonic flight vibration. The test configuration, equipment, and methodology are described. Comparisons with actual flight measurements and previous single exciter simulations are also presented

High speed digital holographic interferometry for hypersonic flow visualization

Science.gov (United States)

Hegde, G. M.; Jagdeesh, G.; Reddy, K. P. J.

2013-06-01

Optical imaging techniques have played a major role in understanding the flow dynamics of varieties of fluid flows, particularly in the study of hypersonic flows. Schlieren and shadowgraph techniques have been the flow diagnostic tools for the investigation of compressible flows since more than a century. However these techniques provide only the qualitative information about the flow field. Other optical techniques such as holographic interferometry and laser induced fluorescence (LIF) have been used extensively for extracting quantitative information about the high speed flows. In this paper we present the application of digital holographic interferometry (DHI) technique integrated with short duration hypersonic shock tunnel facility having 1 ms test time, for quantitative flow visualization. Dynamics of the flow fields in hypersonic/supersonic speeds around different test models is visualized with DHI using a high-speed digital camera (0.2 million fps). These visualization results are compared with schlieren visualization and CFD simulation results. Fringe analysis is carried out to estimate the density of the flow field.

Frequencies of inaudible high-frequency sounds differentially affect brain activity: positive and negative hypersonic effects.

Directory of Open Access Journals (Sweden)

Ariko Fukushima

Full Text Available The hypersonic effect is a phenomenon in which sounds containing significant quantities of non-stationary high-frequency components (HFCs above the human audible range (max. 20 kHz activate the midbrain and diencephalon and evoke various physiological, psychological and behavioral responses. Yet important issues remain unverified, especially the relationship existing between the frequency of HFCs and the emergence of the hypersonic effect. In this study, to investigate the relationship between the hypersonic effect and HFC frequencies, we divided an HFC (above 16 kHz of recorded gamelan music into 12 band components and applied them to subjects along with an audible component (below 16 kHz to observe changes in the alpha2 frequency component (10-13 Hz of spontaneous EEGs measured from centro-parieto-occipital regions (Alpha-2 EEG, which we previously reported as an index of the hypersonic effect. Our results showed reciprocal directional changes in Alpha-2 EEGs depending on the frequency of the HFCs presented with audible low-frequency component (LFC. When an HFC above approximately 32 kHz was applied, Alpha-2 EEG increased significantly compared to when only audible sound was applied (positive hypersonic effect, while, when an HFC below approximately 32 kHz was applied, the Alpha-2 EEG decreased (negative hypersonic effect. These findings suggest that the emergence of the hypersonic effect depends on the frequencies of inaudible HFC.

Frequencies of inaudible high-frequency sounds differentially affect brain activity: positive and negative hypersonic effects.

Science.gov (United States)

Fukushima, Ariko; Yagi, Reiko; Kawai, Norie; Honda, Manabu; Nishina, Emi; Oohashi, Tsutomu

2014-01-01

The hypersonic effect is a phenomenon in which sounds containing significant quantities of non-stationary high-frequency components (HFCs) above the human audible range (max. 20 kHz) activate the midbrain and diencephalon and evoke various physiological, psychological and behavioral responses. Yet important issues remain unverified, especially the relationship existing between the frequency of HFCs and the emergence of the hypersonic effect. In this study, to investigate the relationship between the hypersonic effect and HFC frequencies, we divided an HFC (above 16 kHz) of recorded gamelan music into 12 band components and applied them to subjects along with an audible component (below 16 kHz) to observe changes in the alpha2 frequency component (10-13 Hz) of spontaneous EEGs measured from centro-parieto-occipital regions (Alpha-2 EEG), which we previously reported as an index of the hypersonic effect. Our results showed reciprocal directional changes in Alpha-2 EEGs depending on the frequency of the HFCs presented with audible low-frequency component (LFC). When an HFC above approximately 32 kHz was applied, Alpha-2 EEG increased significantly compared to when only audible sound was applied (positive hypersonic effect), while, when an HFC below approximately 32 kHz was applied, the Alpha-2 EEG decreased (negative hypersonic effect). These findings suggest that the emergence of the hypersonic effect depends on the frequencies of inaudible HFC.

Optimization of the Upper Surface of Hypersonic Vehicle Based on CFD Analysis

Science.gov (United States)

Gao, T. Y.; Cui, K.; Hu, S. C.; Wang, X. P.; Yang, G. W.

2011-09-01

For the hypersonic vehicle, the aerodynamic performance becomes more intensive. Therefore, it is a significant event to optimize the shape of the hypersonic vehicle to achieve the project demands. It is a key technology to promote the performance of the hypersonic vehicle with the method of shape optimization. Based on the existing vehicle, the optimization to the upper surface of the Simplified hypersonic vehicle was done to obtain a shape which suits the project demand. At the cruising condition, the upper surface was parameterized with the B-Spline curve method. The incremental parametric method and the reconstruction technology of the local mesh were applied here. The whole flow field was been calculated and the aerodynamic performance of the craft were obtained by the computational fluid dynamic (CFD) technology. Then the vehicle shape was optimized to achieve the maximum lift-drag ratio at attack angle 3°, 4° and 5°. The results will provide the reference for the practical design.

Detailed modeling of electron emission for transpiration cooling of hypersonic vehicles

Science.gov (United States)

Hanquist, Kyle M.; Hara, Kentaro; Boyd, Iain D.

2017-02-01

Electron transpiration cooling (ETC) is a recently proposed approach to manage the high heating loads experienced at the sharp leading edges of hypersonic vehicles. Computational fluid dynamics (CFD) can be used to investigate the feasibility of ETC in a hypersonic environment. A modeling approach is presented for ETC, which includes developing the boundary conditions for electron emission from the surface, accounting for the space-charge limit effects of the near-wall plasma sheath. The space-charge limit models are assessed using 1D direct-kinetic plasma sheath simulations, taking into account the thermionically emitted electrons from the surface. The simulations agree well with the space-charge limit theory proposed by Takamura et al. for emitted electrons with a finite temperature, especially at low values of wall bias, which validates the use of the theoretical model for the hypersonic CFD code. The CFD code with the analytical sheath models is then used for a test case typical of a leading edge radius in a hypersonic flight environment. The CFD results show that ETC can lower the surface temperature of sharp leading edges of hypersonic vehicles, especially at higher velocities, due to the increase in ionized species enabling higher electron heat extraction from the surface. The CFD results also show that space-charge limit effects can limit the ETC reduction of surface temperatures, in comparison to thermionic emission assuming no effects of the electric field within the sheath.

Modeling and Analysis of an Air-Breathing Flexible Hypersonic Vehicle

Directory of Open Access Journals (Sweden)

Xi-bin Zhang

2014-01-01

Full Text Available By using light-weighted material in hypersonic vehicle, the vehicle body can be easily deformed. The mutual couplings in aerodynamics, flexible structure, and propulsion system will bring great challenges for vehicle modeling. In this work, engineering estimated method is used to calculate the aerodynamic forces, moments, and flexible modes to get the physics-based model of an air-breathing flexible hypersonic vehicle. The model, which contains flexible effects and viscous effects, can capture the physical characteristics of high-speed flight. To overcome the analytical intractability of the model, a simplified control-oriented model of the hypersonic vehicle is presented with curve fitting approximations. The control-oriented model can not only reduce the complexity of the model, but also retain aero-flexible structure-propulsion interactions of the physics-based model and can be applied for nonlinear control.

Toward a CFD nose-to-tail capability - Hypersonic unsteady Navier-Stokes code validation

Science.gov (United States)

Edwards, Thomas A.; Flores, Jolen

1989-01-01

Computational fluid dynamics (CFD) research for hypersonic flows presents new problems in code validation because of the added complexity of the physical models. This paper surveys code validation procedures applicable to hypersonic flow models that include real gas effects. The current status of hypersonic CFD flow analysis is assessed with the Compressible Navier-Stokes (CNS) code as a case study. The methods of code validation discussed to beyond comparison with experimental data to include comparisons with other codes and formulations, component analyses, and estimation of numerical errors. Current results indicate that predicting hypersonic flows of perfect gases and equilibrium air are well in hand. Pressure, shock location, and integrated quantities are relatively easy to predict accurately, while surface quantities such as heat transfer are more sensitive to the solution procedure. Modeling transition to turbulence needs refinement, though preliminary results are promising.

Multi Laser Pulse Investigation of the DEAS Concept in Hypersonic Flow

International Nuclear Information System (INIS)

Minucci, M.A.S.; Toro, P.G.P.; Oliveira, A.C.; Chanes, J.B. Jr.; Ramos, A.G.; Nagamatsu, H.T.; Myrabo, L.N.

2004-01-01

The present paper presents recent experimental results on the Laser-Supported Directed Energy 'Air Spike' - DEAS in hypersonic flow achieved by the Laboratory of Aerothermodynamics and Hypersonics - LAH, Brazil. Two CO2 TEA lasers, sharing the same optical cavity, have been used in conjunction with the IEAv 0.3m Hypersonic Shock Tunnel - HST to demonstrate the Laser-Supported DEAS concept. A single and double laser pulse, generated during the tunnel useful test time, were focused through a NaCl lens upstream of a Double Apollo Disc model fitted with seven piezoelectric pressure transducers and six platinum thin film heat transfer gauges. The objective being to corroborate previous results as well as to obtain additional pressure and heat flux distributions information when two laser pulses are used

Numerical analysis of a hypersonic turbulent and laminar flow using a commercial CFD solver

OpenAIRE

Pajčin Miroslav P.; Simonović Aleksandar M.; Ivanov Toni D.; Komarov Dragan M.; Stupar Slobodan N.

2017-01-01

Computational fluid dynamics computations for two hypersonic flow cases using the commercial ANSYS FLUENT 16.2 CFD software were done. In this paper, an internal and external hypersonic flow cases were considered and analysis of the hypersonic flow using different turbulence viscosity models available in ANSYS FLUENT 16.2 as well as the laminar viscosity model were done. The obtained results were after compared and commented upon. [Project of the Serbian Ministry of Education, Science and Tec...

Hypersonic Vehicle Propulsion System Simplified Model Development

Science.gov (United States)

Stueber, Thomas J.; Raitano, Paul; Le, Dzu K.; Ouzts, Peter

2007-01-01

This document addresses the modeling task plan for the hypersonic GN&C GRC team members. The overall propulsion system modeling task plan is a multi-step process and the task plan identified in this document addresses the first steps (short term modeling goals). The procedures and tools produced from this effort will be useful for creating simplified dynamic models applicable to a hypersonic vehicle propulsion system. The document continues with the GRC short term modeling goal. Next, a general description of the desired simplified model is presented along with simulations that are available to varying degrees. The simulations may be available in electronic form (FORTRAN, CFD, MatLab,...) or in paper form in published documents. Finally, roadmaps outlining possible avenues towards realizing simplified model are presented.

Hypersonic Air Flow with Finite Rate Chemistry

National Research Council Canada - National Science Library

Boyd, Ian

1997-01-01

... describe the effects of non-equilibrium flow chemistry, shock interaction, and turbulent mixing and combustion on the performance of vehicles and air breathing engines designed to fly in the hypersonic flow...

NATO Advanced Study Institute on Molecular Physics and Hypersonic Flows

CERN Document Server

1996-01-01

Molecular Physics and Hypersonic Flows bridges the gap between the fluid dynamics and molecular physics communities, emphasizing the role played by elementary processes in hypersonic flows. In particular, the work is primarily dedicated to filling the gap between microscopic and macroscopic treatments of the source terms to be inserted in the fluid dynamics codes. The first part of the book describes the molecular dynamics of elementary processes both in the gas phase and in the interaction with surfaces by using quantum mechanical and phenomenological approaches. A second group of contributions describes thermodynamics and transport properties of air components, with special attention to the transport of internal energy. A series of papers is devoted to the experimental and theoretical study of the flow of partially ionized gases. Subsequent contributions treat modern computational techniques for 3-D hypersonic flow. Non-equilibrium vibrational kinetics are then described, together with the coupling of vibra...

Heat Transfer Analysis of Thermal Protection Structures for Hypersonic Vehicles

Science.gov (United States)

Zhou, Chen; Wang, Zhijin; Hou, Tianjiao

2017-11-01

This research aims to develop an analytical approach to study the heat transfer problem of thermal protection systems (TPS) for hypersonic vehicles. Laplace transform and integral method are used to describe the temperature distribution through the TPS subject to aerodynamic heating during flight. Time-dependent incident heat flux is also taken into account. Two different cases with heat flux and radiation boundary conditions are studied and discussed. The results are compared with those obtained by finite element analyses and show a good agreement. Although temperature profiles of such problems can be readily accessed via numerical simulations, analytical solutions give a greater insight into the physical essence of the heat transfer problem. Furthermore, with the analytical approach, rapid thermal analyses and even thermal optimization can be achieved during the preliminary TPS design.

Hypersonic wind-tunnel free-flying experiments with onboard instrumentation

KAUST Repository

Mudford, Neil R.; O'Byrne, Sean B.; Neely, Andrew J.; Buttsworth, David R.; Balage, Sudantha

2015-01-01

Hypersonic wind-tunnel testing with "free-flight" models unconnected to a sting ensures that sting/wake flow interactions do not compromise aerodynamic coefficient measurements. The development of miniaturized electronics has allowed the demonstration of a variant of a new method for the acquisition of hypersonic model motion data using onboard accelerometers, gyroscopes, and a microcontroller. This method is demonstrated in a Mach 6 wind-tunnel flow, whose duration and pitot pressure are sufficient for the model to move a body length or more and turn through a significant angle. The results are compared with those obtained from video analysis of the model motion, the existing method favored for obtaining aerodynamic coefficients in similar hypersonic wind-tunnel facilities. The results from the two methods are in good agreement. The new method shows considerable promise for reliable measurement of aerodynamic coefficients, particularly because the data obtained are in more directly applicable forms of accelerations and rates of turn, rather than the model position and attitude obtained from the earlier visualization method. The ideal may be to have both methods operating together.

On air-chemistry reduction for hypersonic external flow applications

International Nuclear Information System (INIS)

Ibrahim, Ashraf; Suman, Sawan; Girimaji, Sharath S.

2015-01-01

Highlights: • The existence of the slow manifold for the air-mixture system is shown. • The QSSA estimate of the slow manifold is fairly accurate. • For mid-temperature range the reduction mechanisms could be useful. - Abstract: In external hypersonic flows, viscous and compressibility effects generate very high temperatures leading to significant chemical reactions among air constituents. Therefore, hypersonic flow computations require coupled calculations of flow and chemistry. Accurate and efficient computations of air-chemistry kinetics are of much importance for many practical applications but calculations accounting for detailed chemical kinetics can be prohibitively expensive. In this paper, we investigate the possibility of applying chemical kinetics reduction schemes for hypersonic air-chemistry. We consider two chemical kinetics sets appropriate for three different temperature ranges: 2500 K to 4500 K; 4500 K to 9000 K; and above 9000 K. By demonstrating the existence of the so-called the slow manifold in each of the chemistry sets, we show that judicious chemical kinetics reduction leading to significant computational savings is possible without much loss in accuracy

Radiation-induced segregation in materials: Implications for accelerator-driven neutron source applications

Energy Technology Data Exchange (ETDEWEB)

Faulkner, R.B.; Song, S. [Loughborough Univ. of Technology (United Kingdom)

1995-10-01

This paper reviews exisiting models for radiation-induced segregation to microstrucural interfaces and surfaces. It indicates how the models have been successfully used in the past in neutron irradiation situations and how they may be modified to account for accelerator-driven RIS. The predictions of the models suggest that any impurity with large misfit will suffer RIS and that the effect is heightened as radiation damage increases. The paper suggests methods to utilise the RIS in transmutation technology by dynamically segregating long life nuclides to preferred sites in the microstructure so that subsequent transmutations occur with maximum efficiency.

Numerical analysis of a hypersonic turbulent and laminar flow using a commercial CFD solver

Directory of Open Access Journals (Sweden)

Pajčin Miroslav P.

2017-01-01

Full Text Available Computational fluid dynamics computations for two hypersonic flow cases using the commercial ANSYS FLUENT 16.2 CFD software were done. In this paper, an internal and external hypersonic flow cases were considered and analysis of the hypersonic flow using different turbulence viscosity models available in ANSYS FLUENT 16.2 as well as the laminar viscosity model were done. The obtained results were after compared and commented upon. [Project of the Serbian Ministry of Education, Science and Technological Development, Grant no. 35035

Viscous-shock-layer solutions for turbulent flow of radiating gas mixtures in chemical equilibrium

Science.gov (United States)

Anderson, E. C.; Moss, J. N.

1975-01-01

The viscous-shock-layer equations for hypersonic laminar and turbulent flows of radiating or nonradiating gas mixtures in chemical equilibrium are presented for two-dimensional and axially-symmetric flow fields. Solutions were obtained using an implicit finite-difference scheme and results are presented for hypersonic flow over spherically-blunted cone configurations at freestream conditions representative of entry into the atmosphere of Venus. These data are compared with solutions obtained using other methods of analysis.

Viscous shock layer solutions for turbulent flow of radiating gas mixtures in chemical equilibrium

Science.gov (United States)

Anderson, E. C.; Moss, J. N.

1975-01-01

The viscous shock layer equations for hypersonic laminar and turbulent flows of radiating or nonradiating gas mixtures in chemical equilibrium are presented for two-dimensional and axially symmetric flow fields. Solutions are obtained using an implicit finite difference scheme and results are presented for hypersonic flow over spherically blunted cone configurations at free stream conditions representative of entry into the atmosphere of Venus. These data are compared with solutions obtained using other methods of analysis.

Flow visualization of a low density hypersonic flow field

International Nuclear Information System (INIS)

Masson, B.S.; Jumper, E.J.; Walters, E.; Segalman, T.Y.; Founds, N.D.

1989-01-01

Characteristics of laser induced iodine fluorescence (LIIF) in low density hypersonic flows are being investigated for use as a diagnostic technique. At low pressures, doppler broadening dominates the iodine absorption profile producing a fluorescence signal that is primarily temperature and velocity dependent. From this dependency, a low pressure flow field has the potential to be mapped for its velocity and temperature fields. The theory for relating iodine emission to the velocity and temperature fields of a hypersonic flow is discussed in this paper. Experimental observations are made of a fluorescencing free expansion and qualitatively related to the theory. 7 refs

Hypersonic - Model Analysis as a Service

DEFF Research Database (Denmark)

Acretoaie, Vlad; Störrle, Harald

2014-01-01

Hypersonic is a Cloud-based tool that proposes a new approach to the deployment of model analysis facilities. It is implemented as a RESTful Web service API o_ering analysis features such as model clone detection. This approach allows the migration of resource intensive analysis algorithms from...

Status of Turbulence Modeling for Hypersonic Propulsion Flowpaths

Science.gov (United States)

Georgiadis, Nicholas J.; Yoder, Dennis A.; Vyas, Manan A.; Engblom, William A.

2012-01-01

This report provides an assessment of current turbulent flow calculation methods for hypersonic propulsion flowpaths, particularly the scramjet engine. Emphasis is placed on Reynolds-averaged Navier-Stokes (RANS) methods, but some discussion of newer meth- ods such as Large Eddy Simulation (LES) is also provided. The report is organized by considering technical issues throughout the scramjet-powered vehicle flowpath including laminar-to-turbulent boundary layer transition, shock wave / turbulent boundary layer interactions, scalar transport modeling (specifically the significance of turbulent Prandtl and Schmidt numbers) and compressible mixing. Unit problems are primarily used to conduct the assessment. In the combustor, results from calculations of a direct connect supersonic combustion experiment are also used to address the effects of turbulence model selection and in particular settings for the turbulent Prandtl and Schmidt numbers. It is concluded that RANS turbulence modeling shortfalls are still a major limitation to the accuracy of hypersonic propulsion simulations, whether considering individual components or an overall system. Newer methods such as LES-based techniques may be promising, but are not yet at a maturity to be used routinely by the hypersonic propulsion community. The need for fundamental experiments to provide data for turbulence model development and validation is discussed.

N-S/DSMC hybrid simulation of hypersonic flow over blunt body including wakes

Science.gov (United States)

Li, Zhonghua; Li, Zhihui; Li, Haiyan; Yang, Yanguang; Jiang, Xinyu

2014-12-01

A hybrid N-S/DSMC method is presented and applied to solve the three-dimensional hypersonic transitional flows by employing the MPC (modular Particle-Continuum) technique based on the N-S and the DSMC method. A sub-relax technique is adopted to deal with information transfer between the N-S and the DSMC. The hypersonic flows over a 70-deg spherically blunted cone under different Kn numbers are simulated using the CFD, DSMC and hybrid N-S/DSMC method. The present computations are found in good agreement with DSMC and experimental results. The present method provides an efficient way to predict the hypersonic aerodynamics in near-continuum transitional flow regime.

Assessment of CFD capability for prediction of hypersonic shock interactions

Science.gov (United States)

Knight, Doyle; Longo, José; Drikakis, Dimitris; Gaitonde, Datta; Lani, Andrea; Nompelis, Ioannis; Reimann, Bodo; Walpot, Louis

2012-01-01

The aerothermodynamic loadings associated with shock wave boundary layer interactions (shock interactions) must be carefully considered in the design of hypersonic air vehicles. The capability of Computational Fluid Dynamics (CFD) software to accurately predict hypersonic shock wave laminar boundary layer interactions is examined. A series of independent computations performed by researchers in the US and Europe are presented for two generic configurations (double cone and cylinder) and compared with experimental data. The results illustrate the current capabilities and limitations of modern CFD methods for these flows.

Detached Eddy Simulations of Hypersonic Transition

Science.gov (United States)

Yoon, S.; Barnhardt, M.; Candler, G.

2010-01-01

This slide presentation reviews the use of Detached Eddy Simulation (DES) of hypersonic transistion. The objective of the study was to investigate the feasibility of using CFD in general, DES in particular, for prediction of roughness-induced boundary layer transition to turbulence and the resulting increase in heat transfer.

Experimental Studies on Hypersonic Stagnation Point Chemical Environment

National Research Council Canada - National Science Library

Chazot, O

2006-01-01

Development of space transportation is a very challenging task. Hypersonic flight should be investigated in details to allow designing spacecraft according to the severe environment of their flight conditions...

Development and Testing of a Shape Memory Alloy-Driven Composite Morphing Radiator

Science.gov (United States)

Walgren, P.; Bertagne, C.; Wescott, M.; Benafan, O.; Erickson, L.; Whitcomb, J.; Hartl, D.

2018-01-01

Future crewed deep space missions will require thermal control systems that can accommodate larger fluctuations in temperature and heat rejection loads than current designs. To maintain the crew cabin at habitable temperatures throughout the entire mission profile, radiators will be required to exhibit turndown ratios (defined as the ratio between the maximum and minimum heat rejection rates) as high as 12:1. Potential solutions to increase radiator turndown ratios include designs that vary the heat rejection rate by changing shape, hence changing the rate of radiation to space. Shape memory alloys exhibit thermally driven phase transformations and thus can be used for both the control and actuation of such a morphing radiator with a single active structural component that transduces thermal energy into motion. This work focuses on designing a high-performance composite radiator panel and investigating the behavior of various SMA actuators in this application. Three designs were fabricated and subsequently tested in a relevant thermal vacuum environment; all three exhibited repeatable morphing behavior, and it is shown through validated computational analysis that the morphing radiator concept can achieve a turndown ratio of 27:1 with a number of simple configuration changes.

Development and Testing of a Shape Memory Alloy-Driven Composite Morphing Radiator

Science.gov (United States)

Walgren, P.; Bertagne, C.; Wescott, M.; Benafan, O.; Erickson, L.; Whitcomb, J.; Hartl, D.

2018-03-01

Future crewed deep space missions will require thermal control systems that can accommodate larger fluctuations in temperature and heat rejection loads than current designs. To maintain the crew cabin at habitable temperatures throughout the entire mission profile, radiators will be required to exhibit turndown ratios (defined as the ratio between the maximum and minimum heat rejection rates) as high as 12:1. Potential solutions to increase radiator turndown ratios include designs that vary the heat rejection rate by changing shape, hence changing the rate of radiation to space. Shape memory alloys exhibit thermally driven phase transformations and thus can be used for both the control and actuation of such a morphing radiator with a single active structural component that transduces thermal energy into motion. This work focuses on designing a high-performance composite radiator panel and investigating the behavior of various SMA actuators in this application. Three designs were fabricated and subsequently tested in a relevant thermal vacuum environment; all three exhibited repeatable morphing behavior, and it is shown through validated computational analysis that the morphing radiator concept can achieve a turndown ratio of 27:1 with a number of simple configuration changes.

Elevator Sizing, Placement, and Control-Relevant Tradeoffs for Hypersonic Vehicles

Science.gov (United States)

Dickeson, Jeffrey J.; Rodriguez, Armando A.; Sridharan, Srikanth; Korad, Akshay

2010-01-01

Within this paper, control-relevant vehicle design concepts are examined using a widely used 3 DOF (plus flexibility) nonlinear model for the longitudinal dynamics of a generic carrot-shaped scramjet powered hypersonic vehicle. The impact of elevator size and placement on control-relevant static properties (e.g. level-flight trimmable region, trim controls, Angle of Attack (AOA), thrust margin) and dynamic properties (e.g. instability and right half plane zero associated with flight path angle) are examined. Elevator usage has been examine for a class of typical hypersonic trajectories.

Ceramic Matrix Composite (CMC) Thermal Protection Systems (TPS) and Hot Structures for Hypersonic Vehicles

Science.gov (United States)

Glass, David E.

2008-01-01

Thermal protection systems (TPS) and hot structures are required for a range of hypersonic vehicles ranging from ballistic reentry to hypersonic cruise vehicles, both within Earth's atmosphere and non-Earth atmospheres. The focus of this paper is on air breathing hypersonic vehicles in the Earth's atmosphere. This includes single-stage to orbit (SSTO), two-stage to orbit (TSTO) accelerators, access to space vehicles, and hypersonic cruise vehicles. This paper will start out with a brief discussion of aerodynamic heating and thermal management techniques to address the high heating, followed by an overview of TPS for rocket-launched and air-breathing vehicles. The argument is presented that as we move from rocket-based vehicles to air-breathing vehicles, we need to move away from the insulated airplane approach used on the Space Shuttle Orbiter to a wide range of TPS and hot structure approaches. The primary portion of the paper will discuss issues and design options for CMC TPS and hot structure components, including leading edges, acreage TPS, and control surfaces. The current state-of-the-art will be briefly discussed for some of the components. The two primary technical challenges impacting the use of CMC TPS and hot structures for hypersonic vehicles are environmental durability and fabrication, and will be discussed briefly.

Experimental Verification of Isotropic Radiation from a Coherent Dipole Source via Electric-Field-Driven LC Resonator Metamaterials

Science.gov (United States)

Tichit, Paul-Henri; Burokur, Shah Nawaz; Qiu, Cheng-Wei; de Lustrac, André

2013-09-01

It has long been conjectured that isotropic radiation by a simple coherent source is impossible due to changes in polarization. Though hypothetical, the isotropic source is usually taken as the reference for determining a radiator’s gain and directivity. Here, we demonstrate both theoretically and experimentally that an isotropic radiator can be made of a simple and finite source surrounded by electric-field-driven LC resonator metamaterials designed by space manipulation. As a proof-of-concept demonstration, we show the first isotropic source with omnidirectional radiation from a dipole source (applicable to all distributed sources), which can open up several possibilities in axion electrodynamics, optical illusion, novel transformation-optic devices, wireless communication, and antenna engineering. Owing to the electric- field-driven LC resonator realization scheme, this principle can be readily applied to higher frequency regimes where magnetism is usually not present.

Laser interferometry of radiation driven gas jets

Science.gov (United States)

Swanson, Kyle James; Ivanov, Vladimir; Mancini, Roberto; Mayes, Daniel C.

2017-06-01

In a series of experiments performed at the 1MA Zebra pulsed power accelerator of the Nevada Terawatt Facility nitrogen gas jets were driven with the broadband x-ray flux produced during the collapse of a wire-array z-pinch implosion. The wire arrays were comprised of 4 and 8, 10μm-thick gold wires and 17μm-thick nickel wires, 2cm and 3cm tall, and 0.3cm in diameter. They radiated 12kJ to 16kJ of x-ray energy, most of it in soft x-ray photons of less than 1keV of energy, in a time interval of 30ns. This x-ray flux was used to drive a nitrogen gas jet located at 0.8cm from the axis of the z-pinch radiation source and produced with a supersonic nozzle. The x-ray flux ionizes the nitrogen gas thus turning it into a photoionized plasma. We used laser interferometry to probe the ionization of the plasma. To this end, a Mach-Zehnder interferometer at the wavelength of 266 nm was set up to extract the atom number density profile of the gas jet just before the Zebra shot, and air-wedge interferometers at 266 and 532 nm were used to determine the electron number density of the plasma right during the Zebra shot. The ratio of electron to atom number densities gives the distribution of average ionization state of the plasma. A python code was developed to perform the image data processing, extract phase shift spatial maps, and obtain the atom and electron number densities via Abel inversion. Preliminary results from the experiment are promising and do show that a plasma has been created in the gas jet driven by the x-ray flux, thus demonstrating the feasibility of a new experimental platform to study photoionized plasmas in the laboratory. These plasmas are found in astrophysical scenarios including x-ray binaries, active galactic nuclei, and the accretion disks surrounding black holes1. This work was sponsored in part by DOE Office of Science Grant DE-SC0014451.1R. C. Mancini et al, Phys. Plasmas 16, 041001 (2009)

Portable Fluorescence Imaging System for Hypersonic Flow Facilities

Science.gov (United States)

Wilkes, J. A.; Alderfer, D. W.; Jones, S. B.; Danehy, P. M.

2003-01-01

A portable fluorescence imaging system has been developed for use in NASA Langley s hypersonic wind tunnels. The system has been applied to a small-scale free jet flow. Two-dimensional images were taken of the flow out of a nozzle into a low-pressure test section using the portable planar laser-induced fluorescence system. Images were taken from the center of the jet at various test section pressures, showing the formation of a barrel shock at low pressures, transitioning to a turbulent jet at high pressures. A spanwise scan through the jet at constant pressure reveals the three-dimensional structure of the flow. Future capabilities of the system for making measurements in large-scale hypersonic wind tunnel facilities are discussed.

An Overview of the NASA FAP Hypersonics Project Airbreathing Propulsion Research

Science.gov (United States)

Auslender, A. H.; Suder, Kenneth L.; Thomas, Scott R.

2009-01-01

The propulsion research portfolio of the National Aeronautics and Space Administration Fundamental Aeronautics Program Hypersonics Project encompasses a significant number of technical tasks that are aligned to achieve mastery and intellectual stewardship of the core competencies in the hypersonic-flight regime. An overall coordinated programmatic and technical effort has been structured to advance the state-of-the-art, via both experimental and analytical efforts. A subset of the entire hypersonics propulsion research portfolio is presented in this overview paper. To this end, two programmatic research disciplines are discussed; namely, (1) the Propulsion Discipline, including three associated research elements: the X-51A partnership, the HIFiRE-2 partnership, and the Durable Combustor Rig, and (2) the Turbine-Based Combine Cycle Discipline, including three associated research elements: the Combined Cycle Engine Large Scale Inlet Mode Transition Experiment, the small-scale Inlet Mode Transition Experiment, and the High-Mach Fan Rig.

Hypersonic force measurements using internal balance based on optical micromachined Fabry-Perot interferometry

Science.gov (United States)

Qiu, Huacheng; Min, Fu; Zhong, Shaolong; Song, Xin; Yang, Yanguang

2018-03-01

Force measurements using wind tunnel balance are necessary for determining a variety of aerodynamic performance parameters, while the harsh environment in hypersonic flows requires that the measurement instrument should be reliable and robust, in against strong electromagnetic interference, high vacuum, or metal (oxide) dusts. In this paper, we demonstrated a three-component internal balance for hypersonic aerodynamic force measurements, using novel optical micromachined Fabry-Perot interferometric (FPI) strain gauges as sensing elements. The FPI gauges were fabricated using Micro-Opto-Electro-Mechanical Systems (MOEMS) surface and bulk fabrication techniques. High-reflectivity coatings are used to form a high-finesse Fabry-Perot cavity, which benefits a high resolution. Antireflective and passivation coatings are used to reduce unwanted interferences. The FPI strain gauge based balance has been calibrated and evaluated in a Mach 5 hypersonic flow. The results are compared with the traditional technique using the foil resistive strain gauge balance, indicating that the proposed balance based on the MOEMS FPI strain gauge is reliable and robust and is potentially suitable for the hypersonic wind tunnel harsh environment.

Surface Heat Flux and Pressure Distribution on a Hypersonic Blunt Body With DEAS

Science.gov (United States)

Salvador, I. I.; Minucci, M. A. S.; Toro, P. G. P.; Oliveira, A. C.; Channes, J. B.

2008-04-01

With the currently growing interest for advanced technologies to enable hypersonic flight comes the Direct Energy Air Spike concept, where pulsed beamed laser energy is focused upstream of a blunt flight vehicle to disrupt the flow structure creating a virtual, slender body geometry. This allies in the vehicle both advantages of a blunt body (lower thermal stresses) to that of a slender geometry (lower wave drag). The research conducted at the Henry T. Nagamatsu Laboratory for Aerodynamics and Hypersonics focused on the measurement of the surface pressure and heat transfer rates on a blunt model. The hypersonic flight conditions were simulated at the HTN Laboratory's 0.3 m T2 Hypersonic Shock Tunnel. During the tests, the laser energy was focused upstream the model by an infrared telescope to create the DEAS effect, which was supplied by a TEA CO2 laser. Piezoelectric pressure transducers were used for the pressure measurements and fast response coaxial thermocouples were used for the measurement of surface temperature, which was later used for the estimation of the wall heat transfer using the inverse heat conduction theory.

MPD model for radar echo signal of hypersonic targets

Directory of Open Access Journals (Sweden)

Xu Xuefei

2014-08-01

Full Text Available The stop-and-go (SAG model is typically used for echo signal received by the radar using linear frequency modulation pulse compression. In this study, the authors demonstrate that this model is not applicable to hypersonic targets. Instead of SAG model, they present a more realistic echo signal model (moving-in-pulse duration (MPD for hypersonic targets. Following that, they evaluate the performances of pulse compression under the SAG and MPD models by theoretical analysis and simulations. They found that the pulse compression gain has an increase of 3 dB by using the MPD model compared with the SAG model in typical cases.

Anisotropic hypersonic phonon propagation in films of aligned ellipsoids.

Science.gov (United States)

Beltramo, Peter J; Schneider, Dirk; Fytas, George; Furst, Eric M

2014-11-14

A material with anisotropic elastic mechanical properties and a direction-dependent hypersonic band gap is fabricated using ac electric field-directed convective self-assembly of colloidal ellipsoids. The frequency of the gap, which is detected in the direction perpendicular to particle alignment and entirely absent parallel to alignment, and the effective sound velocities can be tuned by the particle aspect ratio. We hypothesize that the band gap originates from the primary eigenmode peak, the m-splitted (s,1,2) mode, of the particle resonating with the effective medium. These results reveal the potential for powerful control of the hypersonic phononic band diagram by combining anisotropic particles and self-assembly.

Requirements for facilities and measurement techniques to support CFD development for hypersonic aircraft

Science.gov (United States)

Sellers, William L., III; Dwoyer, Douglas L.

1992-01-01

The design of a hypersonic aircraft poses unique challenges to the engineering community. Problems with duplicating flight conditions in ground based facilities have made performance predictions risky. Computational fluid dynamics (CFD) has been proposed as an additional means of providing design data. At the present time, CFD codes are being validated based on sparse experimental data and then used to predict performance at flight conditions with generally unknown levels of uncertainty. This paper will discuss the facility and measurement techniques that are required to support CFD development for the design of hypersonic aircraft. Illustrations are given of recent success in combining experimental and direct numerical simulation in CFD model development and validation for hypersonic perfect gas flows.

Analysis of Hypersonic Vehicle Wakes

Science.gov (United States)

2015-09-17

Fraction of Cyanide throughout the Flowfield ................................... 131 Figure 122. Mass Fraction of Cyanide at the Nose...hypersonic flow is that as M increases the conservation equations cannot be linearized. The flow properties must be modeled in a complex fashion and can no...ablation present to react with as well. These products of ablation, along with the dissociation and ionization of the gas, gives rise to complex

Hypersonic Threats to the Homeland

Science.gov (United States)

2017-03-28

ADAM) system . This ground based system protects 7 soldiers against rocket threats and utilizes a 10 kW laser with an effective range out to...early warning systems for response to hypersonic threats . The integration of directed energy defensive systems with Space Based Infrared Sensors (SBIRS...and early warning radars already in operation will save costs. By capitalizing on Terminal High Altitude Area Defense (THAAD) system capabilities

On two special values of temperature factor in hypersonic flow stagnation point

Science.gov (United States)

Bilchenko, G. G.; Bilchenko, N. G.

2018-03-01

The hypersonic aircraft permeable cylindrical and spherical surfaces laminar boundary layer heat and mass transfer control mathematical model properties are investigated. The nonlinear algebraic equations systems are obtained for two special values of temperature factor in the hypersonic flow stagnation point. The mappings bijectivity between heat and mass transfer local parameters and controls is established. The computation experiments results are presented: the domains of allowed values “heat-friction” are obtained.

Efficient multigrid computation of steady hypersonic flows

NARCIS (Netherlands)

Koren, B.; Hemker, P.W.; Murthy, T.K.S.

1991-01-01

In steady hypersonic flow computations, Newton iteration as a local relaxation procedure and nonlinear multigrid iteration as an acceleration procedure may both easily fail. In the present chapter, same remedies are presented for overcoming these problems. The equations considered are the steady,

Dynamics Evolution Investigation of Mack Mode Instability in a Hypersonic Boundary Layer by Bicoherence Spectrum Analysis

Science.gov (United States)

Han, Jian; Jiang, Nan

2012-07-01

The instability of a hypersonic boundary layer on a cone is investigated by bicoherence spectrum analysis. The experiment is conducted at Mach number 6 in a hypersonic wind tunnel. The time series signals of instantaneous fluctuating surface-thermal-flux are measured by Pt-thin-film thermocouple temperature sensors mounted at 28 stations on the cone surface along streamwise direction to investigate the development of the unstable disturbances. The bicoherence spectrum analysis based on wavelet transform is employed to investigate the nonlinear interactions of the instability of Mack modes in hypersonic laminar boundary layer transition. The results show that wavelet bicoherence is a powerful tool in studying the unstable mode nonlinear interaction of hypersonic laminar-turbulent transition. The first mode instability gives rise to frequency shifts to higher unstable modes at the early stage of hypersonic laminar-turbulent transition. The modulations subsequently lead to the second mode instability occurrence. The second mode instability governs the last stage of instability and final breakdown to turbulence with multi-scale disturbances growth.

Dynamics Evolution Investigation of Mack Mode Instability in a Hypersonic Boundary Layer by Bicoherence Spectrum Analysis

International Nuclear Information System (INIS)

Han Jian; Jiang Nan

2012-01-01

The instability of a hypersonic boundary layer on a cone is investigated by bicoherence spectrum analysis. The experiment is conducted at Mach number 6 in a hypersonic wind tunnel. The time series signals of instantaneous fluctuating surface-thermal-flux are measured by Pt-thin-film thermocouple temperature sensors mounted at 28 stations on the cone surface along streamwise direction to investigate the development of the unstable disturbances. The bicoherence spectrum analysis based on wavelet transform is employed to investigate the nonlinear interactions of the instability of Mack modes in hypersonic laminar boundary layer transition. The results show that wavelet bicoherence is a powerful tool in studying the unstable mode nonlinear interaction of hypersonic laminar-turbulent transition. The first mode instability gives rise to frequency shifts to higher unstable modes at the early stage of hypersonic laminar-turbulent transition. The modulations subsequently lead to the second mode instability occurrence. The second mode instability governs the last stage of instability and final breakdown to turbulence with multi-scale disturbances growth. (fundamental areas of phenomenology(including applications))

Wavelet Cross-Spectrum Analysis of Multi-Scale Disturbance Instability and Transition on Sharp Cone Hypersonic Boundary Layer

International Nuclear Information System (INIS)

Jian, Han; Nan, Jiang

2008-01-01

Experimental measurement of hypersonic boundary layer stability and transition on a sharp cone with a half angle of 5° is carried out at free-coming stream Mach number 6 in a hypersonic wind tunnel. Mean and fluctuation surface-thermal-flux characteristics of the hypersonic boundary layer flow are measured by Pt-thin-film thermocouple temperature sensors installed at 28 stations on the cone surface along longitudinal direction. At hypersonic speeds, the dominant flow instabilities demonstrate that the growth rate of the second mode tends to exceed that of the low-frequency mode. Wavelet-based cross-spectrum technique is introduced to obtain the multi-scale cross-spectral characteristics of the fluctuating signals in the frequency range of the second mode. Nonlinear interactions both of the second mode disturbance and the first mode disturbance are demonstrated to be dominant instabilities in the initial stage of laminar-turbulence transition for hypersonic shear flow. (fundamental areas of phenomenology (including applications))

Radiatively Driven Hypersonic Wind Tunnel (RDHWT) Program Magnetohydrodynamic Accelerator Research Into Advanced Hypersonics (MARIAH II)

Science.gov (United States)

2000-01-08

addition of large amounts of enthalpy into supersonic air, and establish whether adequate flow chemistry is maintained through the energy deposition...diagnostics for the study of beam profile effects, e-beam-induced flow chemistry , and flow field predictability. These experiments will use an expanded optical...c) Flow chemistry and thermalization. The interaction of the e-beam with the individual gas molecules leads to ionization and chemical

Robust Switching Control for Hypersonic Vehicles, Phase I

Data.gov (United States)

National Aeronautics and Space Administration — Flight in the hypersonic regime is critical to NASA's goals because access to earth orbit and re-entry from orbit to earth or to other planets with atmospheres...

Aeroelasticity, Aerothermoelasticity and Aeroelastic Scaling of Hypersonic Vehicles

National Research Council Canada - National Science Library

Freidmann, Peretz P; Powell, Kenneth G

2004-01-01

...) the behavior of a complete generic hypersonic vehicle. For problems (a) the unsteady airloads were computed using third order piston theory, as well a CFD based Euler and Navier-Stokes loads. For case (b...

Second-mode control in hypersonic boundary layers over assigned complex wall impedance

Science.gov (United States)

Sousa, Victor; Patel, Danish; Chapelier, Jean-Baptiste; Scalo, Carlo

2017-11-01

The durability and aerodynamic performance of hypersonic vehicles greatly relies on the ability to delay transition to turbulence. Passive aerodynamic flow control devices such as porous acoustic absorbers are a very attractive means to damp ultrasonic second-mode waves, which govern transition in hypersonic boundary layers under idealized flow conditions (smooth walls, slender geometries, small angles of attack). The talk will discuss numerical simulations modeling such absorbers via the time-domain impedance boundary condition (TD-IBC) approach by Scalo et al. in a hypersonic boundary layer flow over a 7-degree wedge at freestream Mach numbers M∞ = 7.3 and Reynolds numbers Rem = 1.46 .106 . A three-parameter impedance model tuned to the second-mode waves is tested first with varying resistance, R, and damping ratio, ζ, revealing complete mode attenuation for R workers at DLR-Göttingen.

Progress with multigrid schemes for hypersonic flow problems

International Nuclear Information System (INIS)

Radespiel, R.; Swanson, R.C.

1995-01-01

Several multigrid schemes are considered for the numerical computation of viscous hypersonic flows. For each scheme, the basic solution algorithm employs upwind spatial discretization with explicit multistage time stepping. Two-level versions of the various multigrid algorithms are applied to the two-dimensional advection equation, and Fourier analysis is used to determine their damping properties. The capabilities of the multigrid methods are assessed by solving three different hypersonic flow problems. Some new multigrid schemes based on semicoarsening strategies are shown to be quite effective in relieving the stiffness caused by the high-aspect-ratio cells required to resolve high Reynolds number flows. These schemes exhibit good convergence rates for Reynolds numbers up to 200 X 10 6 and Mach numbers up to 25. 32 refs., 31 figs., 1 tab

Hypersonic nozzle/afterbody CFD code validation. I - Experimental measurements

Science.gov (United States)

Spaid, Frank W.; Keener, Earl R.

1993-01-01

This study was conducted to obtain a detailed experimental description of the flow field created by the interaction of a single-expansion-ramp-nozzle flow with a hypersonic external stream. Data were obtained from a generic nozzle/afterbody model in the 3.5-Foot Hypersonic Wind Tunnel of the NASA Ames Research Center in a cooperative experimental program involving Ames and the McDonnell Douglas Research Laboratories. This paper presents experimental results consisting primarily of surveys obtained with a five-hole total-pressure/flow-direction probe and a total-temperature probe. These surveys were obtained in the flow field created by the interaction between the underexpanded jet plume and the external flow.

DSMC simulation of two-phase plume flow with UV radiation

Energy Technology Data Exchange (ETDEWEB)

Li, Jie; Liu, Ying; Wang, Ning; Jin, Ling [College of Aerospace Science and Engineering, National University of Defense Technology, Changsha, Hunan, 410073 (China)

2014-12-09

Rarefied gas-particle two-phase plume in which the phase of particles is liquid or solid flows from a solid propellant rocket of hypersonic vehicle flying at high altitudes, the aluminum oxide particulates not only impact the rarefied gas flow properties, but also make a great difference to plume radiation signature, so the radiation prediction of the rarefied gas-particle two-phase plume flow is very important for space target detection of hypersonic vehicles. Accordingly, this project aims to study the rarefied gas-particle two-phase flow and ultraviolet radiation (UV) characteristics. Considering a two-way interphase coupling of momentum and energy, the direct simulation Monte Carlo (DSMC) method is developed for particle phase change and the particle flow, including particulate collision, coalescence as well as separation, and a Monte Carlo ray trace model is implemented for the particulate UV radiation. A program for the numerical simulation of the gas-particle two-phase flow and radiation in which the gas flow nonequilibrium is strong is implemented as well. Ultraviolet radiation characteristics of the particle phase is studied based on the calculation of the flow field coupled with the radiation calculation, the radiation model for different size particles is analyzed, focusing on the effects of particle emission, absorption, scattering as well as the searchlight emission of the nozzle. A new approach may be proposed to describe the rarefied gas-particle two-phase plume flow and radiation transfer characteristics in this project.

DSMC simulation of two-phase plume flow with UV radiation

Science.gov (United States)

Li, Jie; Liu, Ying; Wang, Ning; Jin, Ling

2014-12-01

Rarefied gas-particle two-phase plume in which the phase of particles is liquid or solid flows from a solid propellant rocket of hypersonic vehicle flying at high altitudes, the aluminum oxide particulates not only impact the rarefied gas flow properties, but also make a great difference to plume radiation signature, so the radiation prediction of the rarefied gas-particle two-phase plume flow is very important for space target detection of hypersonic vehicles. Accordingly, this project aims to study the rarefied gas-particle two-phase flow and ultraviolet radiation (UV) characteristics. Considering a two-way interphase coupling of momentum and energy, the direct simulation Monte Carlo (DSMC) method is developed for particle phase change and the particle flow, including particulate collision, coalescence as well as separation, and a Monte Carlo ray trace model is implemented for the particulate UV radiation. A program for the numerical simulation of the gas-particle two-phase flow and radiation in which the gas flow nonequilibrium is strong is implemented as well. Ultraviolet radiation characteristics of the particle phase is studied based on the calculation of the flow field coupled with the radiation calculation, the radiation model for different size particles is analyzed, focusing on the effects of particle emission, absorption, scattering as well as the searchlight emission of the nozzle. A new approach may be proposed to describe the rarefied gas-particle two-phase plume flow and radiation transfer characteristics in this project.

Laser-Driven Very High Energy Electron/Photon Beam Radiation Therapy in Conjunction with a Robotic System

Directory of Open Access Journals (Sweden)

Kazuhisa Nakajima

2014-12-01

Full Text Available We present a new external-beam radiation therapy system using very-high-energy (VHE electron/photon beams generated by a centimeter-scale laser plasma accelerator built in a robotic system. Most types of external-beam radiation therapy are delivered using a machine called a medical linear accelerator driven by radio frequency (RF power amplifiers, producing electron beams with an energy range of 6–20 MeV, in conjunction with modern radiation therapy technologies for effective shaping of three-dimensional dose distributions and spatially accurate dose delivery with imaging verification. However, the limited penetration depth and low quality of the transverse penumbra at such electron beams delivered from the present RF linear accelerators prevent the implementation of advanced modalities in current cancer treatments. These drawbacks can be overcome if the electron energy is increased to above 50 MeV. To overcome the disadvantages of the present RF-based medical accelerators, harnessing recent advancement of laser-driven plasma accelerators capable of producing 1-GeV electron beams in a 1-cm gas cell, we propose a new embodiment of the external-beam radiation therapy robotic system delivering very high-energy electron/photon beams with an energy of 50–250 MeV; it is more compact, less expensive, and has a simpler operation and higher performance in comparison with the current radiation therapy system.

A reduced order aerothermodynamic modeling framework for hypersonic vehicles based on surrogate and POD

Directory of Open Access Journals (Sweden)

Chen Xin

2015-10-01

Full Text Available Aerothermoelasticity is one of the key technologies for hypersonic vehicles. Accurate and efficient computation of the aerothermodynamics is one of the primary challenges for hypersonic aerothermoelastic analysis. Aimed at solving the shortcomings of engineering calculation, computation fluid dynamics (CFD and experimental investigation, a reduced order modeling (ROM framework for aerothermodynamics based on CFD predictions using an enhanced algorithm of fast maximin Latin hypercube design is developed. Both proper orthogonal decomposition (POD and surrogate are considered and compared to construct ROMs. Two surrogate approaches named Kriging and optimized radial basis function (ORBF are utilized to construct ROMs. Furthermore, an enhanced algorithm of fast maximin Latin hypercube design is proposed, which proves to be helpful to improve the precisions of ROMs. Test results for the three-dimensional aerothermodynamic over a hypersonic surface indicate that: the ROMs precision based on Kriging is better than that by ORBF, ROMs based on Kriging are marginally more accurate than ROMs based on POD-Kriging. In a word, the ROM framework for hypersonic aerothermodynamics has good precision and efficiency.

The Additional Error of Inertial Sensors Induced by Hypersonic Flight Conditions.

Science.gov (United States)

Karachun, Volodimir; Mel'nick, Viktorij; Korobiichuk, Igor; Nowicki, Michał; Szewczyk, Roman; Kobzar, Svitlana

2016-02-26

The emergence of hypersonic technology pose a new challenge for inertial navigation sensors, widely used in aerospace industry. The main problems are: extremely high temperatures, vibration of the fuselage, penetrating acoustic radiation and shock N-waves. The nature of the additional errors of the gyroscopic inertial sensor with hydrostatic suspension components under operating conditions generated by forced precession of the movable part of the suspension due to diffraction phenomena in acoustic fields is explained. The cause of the disturbing moments in the form of the Coriolis inertia forces during the transition of the suspension surface into the category of impedance is revealed. The boundaries of occurrence of the features on the resonance wave match are described. The values of the "false" angular velocity as a result of the elastic-stress state of suspension in the acoustic fields are determined.

Advanced Control System Design for Hypersonic Vehicles, Phase I

Data.gov (United States)

National Aeronautics and Space Administration — Guidance and control system design for hypersonic vehicles is more challenging than their subsonic and supersonic counterparts. Some of these challenges are (i)...

Parametric Analysis of a Hypersonic Inlet using Computational Fluid Dynamics

Science.gov (United States)

Oliden, Daniel

For CFD validation, hypersonic flow fields are simulated and compared with experimental data specifically designed to recreate conditions found by hypersonic vehicles. Simulated flow fields on a cone-ogive with flare at Mach 7.2 are compared with experimental data from NASA Ames Research Center 3.5" hypersonic wind tunnel. A parametric study of turbulence models is presented and concludes that the k-kl-omega transition and SST transition turbulence model have the best correlation. Downstream of the flare's shockwave, good correlation is found for all boundary layer profiles, with some slight discrepancies of the static temperature near the surface. Simulated flow fields on a blunt cone with flare above Mach 10 are compared with experimental data from CUBRC LENS hypervelocity shock tunnel. Lack of vibrational non-equilibrium calculations causes discrepancies in heat flux near the leading edge. Temperature profiles, where non-equilibrium effects are dominant, are compared with the dissociation of molecules to show the effects of dissociation on static temperature. Following the validation studies is a parametric analysis of a hypersonic inlet from Mach 6 to 20. Compressor performance is investigated for numerous cowl leading edge locations up to speeds of Mach 10. The variable cowl study showed positive trends in compressor performance parameters for a range of Mach numbers that arise from maximizing the intake of compressed flow. An interesting phenomenon due to the change in shock wave formation for different Mach numbers developed inside the cowl that had a negative influence on the total pressure recovery. Investigation of the hypersonic inlet at different altitudes is performed to study the effects of Reynolds number, and consequently, turbulent viscous effects on compressor performance. Turbulent boundary layer separation was noted as the cause for a change in compressor performance parameters due to a change in Reynolds number. This effect would not be

Evaluation of CFD Turbulent Heating Prediction Techniques and Comparison With Hypersonic Experimental Data

Science.gov (United States)

Dilley, Arthur D.; McClinton, Charles R. (Technical Monitor)

2001-01-01

Results from a study to assess the accuracy of turbulent heating and skin friction prediction techniques for hypersonic applications are presented. The study uses the original and a modified Baldwin-Lomax turbulence model with a space marching code. Grid converged turbulent predictions using the wall damping formulation (original model) and local damping formulation (modified model) are compared with experimental data for several flat plates. The wall damping and local damping results are similar for hot wall conditions, but differ significantly for cold walls, i.e., T(sub w) / T(sub t) hypersonic vehicles. Based on the results of this study, it is recommended that the local damping formulation be used with the Baldwin-Lomax and Cebeci-Smith turbulence models in design and analysis of Hyper-X and future hypersonic vehicles.

Systems Challenges for Hypersonic Vehicles

Science.gov (United States)

Hunt, James L.; Laruelle, Gerard; Wagner, Alain

1997-01-01

This paper examines the system challenges posed by fully reusable hypersonic cruise airplanes and access to space vehicles. Hydrocarbon and hydrogen fueled airplanes are considered with cruise speeds of Mach 5 and 10, respectively. The access to space matrix is examined. Airbreathing and rocket powered, single- and two-stage vehicles are considered. Reference vehicle architectures are presented. Major systems/subsystems challenges are described. Advanced, enhancing systems concepts as well as common system technologies are discussed.

Hypersonic Navier Stokes Comparisons to Orbiter Flight Data

Science.gov (United States)

Campbell, Charles H.; Nompelis, Ioannis; Candler, Graham; Barnhart, Michael; Yoon, Seokkwan

2009-01-01

Hypersonic chemical nonequilibrium simulations of low earth orbit entry flow fields are becoming increasingly commonplace as software and computational capabilities become more capable. However, development of robust and accurate software to model these environments will always encounter a significant barrier in developing a suite of high quality calibration cases. The US3D hypersonic nonequilibrium Navier Stokes analysis capability has been favorably compared to a number of wind tunnel test cases. Extension of the calibration basis for this software to Orbiter flight conditions will provide an incremental increase in confidence. As part of the Orbiter Boundary Layer Transition Flight Experiment and the Hypersonic Thermodynamic Infrared Measurements project, NASA is performing entry flight testing on the Orbiter to provide valuable aerothermodynamic heating data. An increase in interest related to orbiter entry environments is resulting from this activity. With the advent of this new data, comparisons of the US3D software to the new flight testing data is warranted. This paper will provide information regarding the framework of analyses that will be applied with the US3D analysis tool. In addition, comparisons will be made to entry flight testing data provided by the Orbiter BLT Flight Experiment and HYTHIRM projects. If data from digital scans of the Orbiter windward surface become available, simulations will also be performed to characterize the difference in surface heating between the CAD reference OML and the digitized surface provided by the surface scans.

Molecular Diagnostics for the Study of Hypersonic Flows

Science.gov (United States)

2000-04-01

UNCLASSIFIED Defense Technical Information Center Compilation Part Notice ADPO10744 TITLE: Molecular Diagnostics for the Study of Hypersonic Flows...following component part numbers comprise the compilation report: ADP010736 thru ADPO10751 UNCLASSIFIED 5-1 Molecular Diagnostics for the Study of

Applications of an implicit HLLC-based Godunov solver for steady state hypersonic problems

International Nuclear Information System (INIS)

Link, R.A.; Sharman, B.

2005-01-01

Over the past few years, there has been considerable activity developing research vehicles for studying hypersonic propulsion. Successful launches of the Australian Hyshot and the US Hyper-X vehicles have added a significant amount of flight test data to a field that had previously been limited to numerical simulation. A number of approaches have been proposed for hypersonics propulsion, including attached detonation wave, supersonics combustion, and shock induced combustion. Due to the high cost of developing flight hardware, CFD simulations will continue to be a key tool for investigating the feasibility of these concepts. Capturing the interactions of the vehicle body with the boundary layer and chemical reactions pushes the limits of available modelling tools and computer hardware. Explicit formulations are extremely slow in converging to a steady state; therefore, the use of implicit methods are warranted. An implicit LLC-based Godunov solver has been developed at Martec in collaboration with DRDC Valcartier to solve hypersonic problems with a minimum of CPU time and RAM storage. The solver, Chinook Implicit, is based upon the implicit formulation adopted by Batten et. al. The solver is based on a point implicit Gauss-Seidel method for unstructured grids, and includes fully implicit boundary conditions. Preliminary results for small and large scale inviscid hypersonics problems will be presented. (author)

On Challenges for Hypersonic Turbulent Simulations

International Nuclear Information System (INIS)

Yee, H.C.; Sjogreen, B.

2009-01-01

This short note discusses some of the challenges for design of suitable spatial numerical schemes for hypersonic turbulent flows, including combustion, and thermal and chemical nonequilibrium flows. Often, hypersonic turbulent flows in re-entry space vehicles and space physics involve mixed steady strong shocks and turbulence with unsteady shocklets. Material mixing in combustion poses additional computational challenges. Proper control of numerical dissipation in numerical methods beyond the standard shock-capturing dissipation at discontinuities is an essential element for accurate and stable simulations of the subject physics. On one hand, the physics of strong steady shocks and unsteady turbulence/shocklet interactions under the nonequilibrium environment is not well understood. On the other hand, standard and newly developed high order accurate (fourth-order or higher) schemes were developed for homogeneous hyperbolic conservation laws and mixed hyperbolic and parabolic partial differential equations (PDEs) (without source terms). The majority of finite rate chemistry and thermal nonequilibrium simulations employ methods for homogeneous time-dependent PDEs with a pointwise evaluation of the source terms. The pointwise evaluation of the source term might not be the best choice for stability, accuracy and minimization of spurious numerics for the overall scheme

Research on radiation characteristics of dipole antenna modulation by sub-wavelength inhomogeneous plasma layer

Directory of Open Access Journals (Sweden)

Fanrong Kong

2018-02-01

Full Text Available The modulation and enhancement effect of sub-wavelength plasma structures on compact antennas exhibits obvious technological advantage and considerable progress. In order to extend the availability of this technology under complex and actual environment with inhomogeneous plasma structure, a numerical simulation analysis based on finite element method has been conducted in this paper. The modulation function of the antenna radiation with sub-wavelength plasma layer located at different positions was investigated, and the inhomogeneous plasma layer with multiple electron density distribution profiles were employed to explore the effect of plasma density distribution on the antenna radiation. It has been revealed that the optical near-field modulated distance and reduced plasma distribution are more beneficial to enhance the radiation. On the basis above, an application-focused research about communication through the plasma sheath surrounding a hypersonic vehicle has been carried out aiming at exploring an effective communication window. The relevant results devote guiding significance in the field of antenna radiation modulation and enhancement, as well as the development of communication technology in hypersonic flight.

Research on radiation characteristics of dipole antenna modulation by sub-wavelength inhomogeneous plasma layer

Science.gov (United States)

Kong, Fanrong; Chen, Peiqi; Nie, Qiuyue; Zhang, Xiaoning; Zhang, Zhen; Jiang, Binhao

2018-02-01

The modulation and enhancement effect of sub-wavelength plasma structures on compact antennas exhibits obvious technological advantage and considerable progress. In order to extend the availability of this technology under complex and actual environment with inhomogeneous plasma structure, a numerical simulation analysis based on finite element method has been conducted in this paper. The modulation function of the antenna radiation with sub-wavelength plasma layer located at different positions was investigated, and the inhomogeneous plasma layer with multiple electron density distribution profiles were employed to explore the effect of plasma density distribution on the antenna radiation. It has been revealed that the optical near-field modulated distance and reduced plasma distribution are more beneficial to enhance the radiation. On the basis above, an application-focused research about communication through the plasma sheath surrounding a hypersonic vehicle has been carried out aiming at exploring an effective communication window. The relevant results devote guiding significance in the field of antenna radiation modulation and enhancement, as well as the development of communication technology in hypersonic flight.

Radiative effects on turbulent buoyancy-driven air flow in open square cavities

International Nuclear Information System (INIS)

Zamora, B.; Kaiser, A.S.

2016-01-01

The effects of the radiative effects and the air variable properties (density, viscosity and thermal conductivity) on the buoyancy-driven flows established in open square cavities are investigated. Two-dimensional, laminar, transitional and turbulent simulations are obtained, considering both uniform wall temperature and uniform heat flux heating conditions. In transitional and turbulent cases, the low- Reynolds k-ω turbulence model is employed. The average Nusselt number and the dimensionless mass-flow rate have been obtained for a wide range of the Rayleigh number varying from 10 3 to 10 16 . The results obtained taking into account the variable thermophysical properties of air are compared to those calculated assuming constant properties and the Boussinesq approximation. In addition, the influence of considering surface radiative effects on the differences reached for the Nusselt number and the mass flow rate obtained with several intensities of heating is studied; specifically, the effects of thermal radiation on the appearance of the burnout phenomenon is analyzed. The changes produced in the flow patterns into the cavity when the radiative heat transfer and the effects of variation of properties are relevant, are also shown. (authors)

Flow-Tagging Velocimetry for Hypersonic Flows Using Fluorescence of Nitric Oxide

Science.gov (United States)

Danehy, P. M.; OByrne, S.; Houwing, A. F. P.

2001-01-01

We investigate a new type of flow-tagging velocimetry technique for hypersonic flows. The technique involves exciting a thin line of nitric oxide molecules with a laser beam and then, after some delay, acquiring an image of the displaced line. One component of velocity is determined from the time of flight. This method is applied to measure the velocity profile in a Mach 8.5 laminar, hypersonic boundary layer in the Australian National Universities T2 free-piston shock tunnel. The velocity is measured with an uncertainty of approximately 2%. Comparison with a CFD simulation of the flow shows reasonable agreement.

Numerical analysis of exhaust jet secondary combustion in hypersonic flow field

Science.gov (United States)

Yang, Tian-Peng; Wang, Jiang-Feng; Zhao, Fa-Ming; Fan, Xiao-Feng; Wang, Yu-Han

2018-05-01

The interaction effect between jet and control surface in supersonic and hypersonic flow is one of the key problems for advanced flight control system. The flow properties of exhaust jet secondary combustion in a hypersonic compression ramp flow field were studied numerically by solving the Navier-Stokes equations with multi-species and combustion reaction effects. The analysis was focused on the flow field structure and the force amplification factor under different jet conditions. Numerical results show that a series of different secondary combustion makes the flow field structure change regularly, and the temperature increases rapidly near the jet exit.

Geometry Modeling and Adaptive Control of Air-Breathing Hypersonic Vehicles

Science.gov (United States)

Vick, Tyler Joseph

Air-breathing hypersonic vehicles have the potential to provide global reach and affordable access to space. Recent technological advancements have made scramjet-powered flight achievable, as evidenced by the successes of the X-43A and X-51A flight test programs over the last decade. Air-breathing hypersonic vehicles present unique modeling and control challenges in large part due to the fact that scramjet propulsion systems are highly integrated into the airframe, resulting in strongly coupled and often unstable dynamics. Additionally, the extreme flight conditions and inability to test fully integrated vehicle systems larger than X-51 before flight leads to inherent uncertainty in hypersonic flight. This thesis presents a means to design vehicle geometries, simulate vehicle dynamics, and develop and analyze control systems for hypersonic vehicles. First, a software tool for generating three-dimensional watertight vehicle surface meshes from simple design parameters is developed. These surface meshes are compatible with existing vehicle analysis tools, with which databases of aerodynamic and propulsive forces and moments can be constructed. A six-degree-of-freedom nonlinear dynamics simulation model which incorporates this data is presented. Inner-loop longitudinal and lateral control systems are designed and analyzed utilizing the simulation model. The first is an output feedback proportional-integral linear controller designed using linear quadratic regulator techniques. The second is a model reference adaptive controller (MRAC) which augments this baseline linear controller with an adaptive element. The performance and robustness of each controller are analyzed through simulated time responses to angle-of-attack and bank angle commands, while various uncertainties are introduced. The MRAC architecture enables the controller to adapt in a nonlinear fashion to deviations from the desired response, allowing for improved tracking performance, stability, and

Probing thermomechanics at the nanoscale: impulsively excited pseudosurface acoustic waves in hypersonic phononic crystals.

Science.gov (United States)

Nardi, Damiano; Travagliati, Marco; Siemens, Mark E; Li, Qing; Murnane, Margaret M; Kapteyn, Henry C; Ferrini, Gabriele; Parmigiani, Fulvio; Banfi, Francesco

2011-10-12

High-frequency surface acoustic waves can be generated by ultrafast laser excitation of nanoscale patterned surfaces. Here we study this phenomenon in the hypersonic frequency limit. By modeling the thermomechanics from first-principles, we calculate the system's initial heat-driven impulsive response and follow its time evolution. A scheme is introduced to quantitatively access frequencies and lifetimes of the composite system's excited eigenmodes. A spectral decomposition of the calculated response on the eigemodes of the system reveals asymmetric resonances that result from the coupling between surface and bulk acoustic modes. This finding allows evaluation of impulsively excited pseudosurface acoustic wave frequencies and lifetimes and expands our understanding of the scattering of surface waves in mesoscale metamaterials. The model is successfully benchmarked against time-resolved optical diffraction measurements performed on one-dimensional and two-dimensional surface phononic crystals, probed using light at extreme ultraviolet and near-infrared wavelengths.

A reduced order aerothermodynamic modeling framework for hypersonic vehicles based on surrogate and POD

OpenAIRE

Chen Xin; Liu Li; Long Teng; Yue Zhenjiang

2015-01-01

Aerothermoelasticity is one of the key technologies for hypersonic vehicles. Accurate and efficient computation of the aerothermodynamics is one of the primary challenges for hypersonic aerothermoelastic analysis. Aimed at solving the shortcomings of engineering calculation, computation fluid dynamics (CFD) and experimental investigation, a reduced order modeling (ROM) framework for aerothermodynamics based on CFD predictions using an enhanced algorithm of fast maximin Latin hypercube design ...

Assessment of predictive capabilities for aerodynamic heating in hypersonic flow

Science.gov (United States)

Knight, Doyle; Chazot, Olivier; Austin, Joanna; Badr, Mohammad Ali; Candler, Graham; Celik, Bayram; Rosa, Donato de; Donelli, Raffaele; Komives, Jeffrey; Lani, Andrea; Levin, Deborah; Nompelis, Ioannis; Panesi, Marco; Pezzella, Giuseppe; Reimann, Bodo; Tumuklu, Ozgur; Yuceil, Kemal

2017-04-01

The capability for CFD prediction of hypersonic shock wave laminar boundary layer interaction was assessed for a double wedge model at Mach 7.1 in air and nitrogen at 2.1 MJ/kg and 8 MJ/kg. Simulations were performed by seven research organizations encompassing both Navier-Stokes and Direct Simulation Monte Carlo (DSMC) methods as part of the NATO STO AVT Task Group 205 activity. Comparison of the CFD simulations with experimental heat transfer and schlieren visualization suggest the need for accurate modeling of the tunnel startup process in short-duration hypersonic test facilities, and the importance of fully 3-D simulations of nominally 2-D (i.e., non-axisymmmetric) experimental geometries.

Disturbance observer-based L1 robust tracking control for hypersonic vehicles with T-S disturbance modeling

Directory of Open Access Journals (Sweden)

Yang Yi

2016-11-01

Full Text Available This article concerns a disturbance observer-based L1 robust anti-disturbance tracking algorithm for the longitudinal models of hypersonic flight vehicles with different kinds of unknown disturbances. On one hand, by applying T-S fuzzy models to represent those modeled disturbances, a disturbance observer relying on T-S disturbance models can be constructed to track the dynamics of exogenous disturbances. On the other hand, L1 index is introduced to analyze the attenuation performance of disturbance for those unmodeled disturbances. By utilizing the existing convex optimization algorithm, a disturbance observer-based proportional-integral-controlled input is proposed such that the stability of hypersonic flight vehicles can be ensured and the tracking error for velocity and altitude in hypersonic flight vehicle models can converge to equilibrium point. Furthermore, the satisfactory disturbance rejection and attenuation with L1 index can be obtained simultaneously. Simulation results on hypersonic flight vehicle models can reflect the feasibility and effectiveness of the proposed control algorithm.

Hypersonic CFD applications for the National Aero-Space Plane

Science.gov (United States)

Richardson, Pamela F.; Mcclinton, Charles R.; Bittner, Robert D.; Dilley, A. Douglas; Edwards, Kelvin W.

1989-01-01

Design and analysis of the NASP depends heavily upon developing the critical technology areas that cover the entire engineering design of the vehicle. These areas include materials, structures, propulsion systems, propellants, integration of airframe and propulsion systems, controls, subsystems, and aerodynamics areas. Currently, verification of many of the classical engineering tools relies heavily on computational fluid dynamics. Advances are being made in the development of CFD codes to accomplish nose-to-tail analyses for hypersonic aircraft. Additional details involving the partial development, analysis, verification, and application of the CFL3D code and the SPARK combustor code are discussed. A nonequilibrium version of CFL3D that is presently being developed and tested is also described. Examples are given of portion calculations for research hypersonic aircraft geometries and comparisons with experiment data show good agreement.

Line-driven disk winds in active galactic nuclei: The critical importance of ionization and radiative transfer

Energy Technology Data Exchange (ETDEWEB)

Higginbottom, Nick; Knigge, Christian; Matthews, James H. [School of Physics and Astronomy, University of Southampton, Highfield, Southampton, SO17 1BJ (United Kingdom); Proga, Daniel [Department of Physics and Astronomy, University of Nevada, Las Vegas, 4505 South Maryland Parkway, Las Vegas, NV 89154-4002 (United States); Long, Knox S. [Space Telescope Science Institute, 3700 San Martin Drive, Baltimore, MD 21218 (United States); Sim, Stuart A., E-mail: nick_higginbottom@fastmail.fm [School of Mathematics and Physics, Queens University Belfast, University Road, Belfast, BT7 1NN (United Kingdom)

2014-07-01

Accretion disk winds are thought to produce many of the characteristic features seen in the spectra of active galactic nuclei (AGNs) and quasi-stellar objects (QSOs). These outflows also represent a natural form of feedback between the central supermassive black hole and its host galaxy. The mechanism for driving this mass loss remains unknown, although radiation pressure mediated by spectral lines is a leading candidate. Here, we calculate the ionization state of, and emergent spectra for, the hydrodynamic simulation of a line-driven disk wind previously presented by Proga and Kallman. To achieve this, we carry out a comprehensive Monte Carlo simulation of the radiative transfer through, and energy exchange within, the predicted outflow. We find that the wind is much more ionized than originally estimated. This is in part because it is much more difficult to shield any wind regions effectively when the outflow itself is allowed to reprocess and redirect ionizing photons. As a result, the calculated spectrum that would be observed from this particular outflow solution would not contain the ultraviolet spectral lines that are observed in many AGN/QSOs. Furthermore, the wind is so highly ionized that line driving would not actually be efficient. This does not necessarily mean that line-driven winds are not viable. However, our work does illustrate that in order to arrive at a self-consistent model of line-driven disk winds in AGN/QSO, it will be critical to include a more detailed treatment of radiative transfer and ionization in the next generation of hydrodynamic simulations.

A numerical study of microparticle acoustophoresis driven by acoustic radiation forces and streaming-induced drag forces

DEFF Research Database (Denmark)

Muller, Peter Barkholt; Barnkob, Rune; Jensen, Mads Jakob Herring

2012-01-01

We present a numerical study of the transient acoustophoretic motion of microparticles suspended in a liquid-filled microchannel and driven by the acoustic forces arising from an imposed standing ultrasound wave: the acoustic radiation force from the scattering of sound waves on the particles...

Radiation effects in materials for accelerator-driven neutron technologies. Revision

International Nuclear Information System (INIS)

Wechsler, M.S.; Lin, C.; Sommer, W.F.

1997-01-01

Accelerator-driven neutron technologies use spallation neutron sources (SNS's) in which high-energy protons bombard a heavy-element target and spallation neutrons are produced. The materials exposed to the most damaging radiation environments in an SNS are those in the path of the incident proton beam. This includes target and window materials. These materials will experience damage from the incident protons and the spallation neutrons. In addition, some materials will be damaged by the spallation neutrons alone. The principal materials of interest for SNS's are discussed elsewhere. The target should consist of one or more heavy elements, so as to increase the number of neutrons produced per incident proton. A liquid metal target (e.g., Pb, Bi, Pb-Bi, Pb-Mg, and Hg) has the advantage of eliminating the effects of radiation damage on the target material itself, but concerns over corrosion problems and the influence of transmutants remain. The major solid targets in operating SNS's and under consideration for the 1-5 MW SNS's are W, U, and Pb. Tungsten is the target material at LANSCE, and is the projected target material for an upgraded LANSCE target that is presently being designed. It is also the projected target material for the tritium producing SNS under design at LANL. In this paper, the authors present the results of spallation radiation damage calculations (displacement and He production) for tungsten

Reduced Order Modeling for Non-equilibrium Radiation Hydrodynamics of Base Flow and Wakes: Enabling Manned Missions to Mars

Data.gov (United States)

National Aeronautics and Space Administration — Understanding non-equilibrium chemical kinetics and its interaction with radiation and fluid mechanics in hypersonic flows remains one of the largest obstacles to...

Numerical simulation for the influence of laser-induced plasmas addition on air mass capture of hypersonic inlet

Science.gov (United States)

Zhao, Wei; Dou, Zhiguo; Li, Qian

2012-03-01

The theory of laser-induced plasmas addition to hypersonic airflow off a vehicle to increase air mass capture and improve the performance of hypersonic inlets at Mach numbers below the design value is explored. For hypersonic vehicles, when flying at mach numbers lower than the design one, we can increase the mass capture ratio of inlet through laser-induced plasmas injection to the hypersonic flow upstream of cowl lip to form a virtual cowl. Based on the theory, the model of interaction between laser-induced plasmas and hypersonic flow was established. The influence on the effect of increasing mass capture ratio was studied at different positions of laser-induced plasmas region for the external compression hypersonic inlet at Mach 5 while the design value is 6, the power of plasmas was in the range of 1-8mJ. The main results are as follows: 1. the best location of the plasma addition region is near the intersection of the nose shock of the vehicle with the continuation of the cowl line, and slightly below that line. In that case, the shock generated by the heating is close to the shock that is a reflection of the vehicle nose shock off the imaginary solid surface-extension of the cowl. 2. Plasma addition does increase mass capture, and the effect becomes stronger as more energy is added, the peak value appeared when the power of plasma was about 4mJ, when the plasma energy continues to get stronger, the mass capture will decline slowly.

A Combined CFD/Characteristic Method for Prediction and Design of Hypersonic Inlet with Nose Bluntness

Science.gov (United States)

Gao, Wenzhi; Li, Zhufei; Yang, Jiming

Leading edge bluntness is widely used in hypersonic inlet design for thermal protection[1]. Detailed research of leading edge bluntness on hypersonic inlet has been concentrated on shock shape correlation[2], boundary layer flow[3], inlet performance[4], etc. It is well known that blunted noses cause detached bow shocks which generate subsonic regions around the noses and entropy layers in the flowfield.

Red Shift and Broadening of Backward Harmonic Radiation from Electron Oscillations Driven by Femtosecond Laser Pulse

International Nuclear Information System (INIS)

Tian Youwei; Yu Wei; Lu Peixiang; Senecha, Vinod K; Han, Xu; Deng Degang; Li Ruxin; Xu Zhizhan

2006-01-01

The characteristics of backward harmonic radiation due to electron oscillations driven by a linearly polarized fs laser pulse are analysed considering a single electron model. The spectral distributions of the electron's backward harmonic radiation are investigated in detail for different parameters of the driver laser pulse. Higher order harmonic radiations are possible for a sufficiently intense driving laser pulse. We have shown that for a realistic pulsed photon beam, the spectrum of the radiation is red shifted as well as broadened because of changes in the longitudinal velocity of the electrons during the laser pulse. These effects are more pronounced at higher laser intensities giving rise to higher order harmonics that eventually leads to a continuous spectrum. Numerical simulations have further shown that by increasing the laser pulse width the broadening of the high harmonic radiations can be controlled

Characteristic Model-Based Robust Model Predictive Control for Hypersonic Vehicles with Constraints

Directory of Open Access Journals (Sweden)

Jun Zhang

2017-06-01

Full Text Available Designing robust control for hypersonic vehicles in reentry is difficult, due to the features of the vehicles including strong coupling, non-linearity, and multiple constraints. This paper proposed a characteristic model-based robust model predictive control (MPC for hypersonic vehicles with reentry constraints. First, the hypersonic vehicle is modeled by a characteristic model composed of a linear time-varying system and a lumped disturbance. Then, the identification data are regenerated by the accumulative sum idea in the gray theory, which weakens effects of the random noises and strengthens regularity of the identification data. Based on the regenerated data, the time-varying parameters and the disturbance are online estimated according to the gray identification. At last, the mixed H2/H∞ robust predictive control law is proposed based on linear matrix inequalities (LMIs and receding horizon optimization techniques. Using active tackling system constraints of MPC, the input and state constraints are satisfied in the closed-loop control system. The validity of the proposed control is verified theoretically according to Lyapunov theory and illustrated by simulation results.

Investigation of advanced propulsion technologies: The RAM accelerator and the flowing gas radiation heater

Science.gov (United States)

Bruckner, A. P.; Knowlen, C.; Mattick, A. T.; Hertzberg, A.

1992-01-01

The two principal areas of advanced propulsion investigated are the ram accelerator and the flowing gas radiation heater. The concept of the ram accelerator is presented as a hypervelocity launcher for large-scale aeroballistic range applications in hypersonics and aerothermodynamics research. The ram accelerator is an in-bore ramjet device in which a projectile shaped like the centerbody of a supersonic ramjet is propelled in a stationary tube filled with a tailored combustible gas mixture. Combustion on and behind the projectile generates thrust which accelerates it to very high velocities. The acceleration can be tailored for the 'soft launch' of instrumented models. The distinctive reacting flow phenomena that have been observed in the ram accelerator are relevant to the aerothermodynamic processes in airbreathing hypersonic propulsion systems and are useful for validating sophisticated CFD codes. The recently demonstrated scalability of the device and the ability to control the rate of acceleration offer unique opportunities for the use of the ram accelerator as a large-scale hypersonic ground test facility. The flowing gas radiation receiver is a novel concept for using solar energy to heat a working fluid for space power or propulsion. Focused solar radiation is absorbed directly in a working gas, rather than by heat transfer through a solid surface. Previous theoretical analysis had demonstrated that radiation trapping reduces energy loss compared to that of blackbody receivers, and enables higher efficiencies and higher peak temperatures. An experiment was carried out to measure the temperature profile of an infrared-active gas and demonstrate the effect of radiation trapping. The success of this effort validates analytical models of heat transfer in this receiver, and confirms the potential of this approach for achieving high efficiency space power and propulsion.

Radiation Belt Transport Driven by Solar Wind Dynamic Pressure Fluctuations

Science.gov (United States)

Kress, B. T.; Hudson, M. K.; Ukhorskiy, A. Y.; Mueller, H.

2012-12-01

The creation of the Earth's outer zone radiation belts is attributed to earthward transport and adiabatic acceleration of electrons by drift-resonant interactions with electromagnetic fluctuations in the magnetosphere. Three types of radial transport driven by solar wind dynamic pressure fluctuations that have been identified are: (1) radial diffusion [Falthammer, 1965], (2) significant changes in the phase space density radial profile due to a single or few ULF drift-resonant interactions [Ukhorskiy et al., 2006; Degeling et al., 2008], and (3) shock associated injections of radiation belt electrons occurring in less than a drift period [Li et al., 1993]. A progress report will be given on work to fully characterize different forms of radial transport and their effect on the Earth's radiation belts. The work is being carried out by computing test-particle trajectories in electric and magnetic fields from a simple analytic ULF field model and from global MHD simulations of the magnetosphere. Degeling, A. W., L. G. Ozeke, R. Rankin, I. R. Mann, and K. Kabin (2008), Drift resonant generation of peaked relativistic electron distributions by Pc 5 ULF waves, textit{J. Geophys. Res., 113}, A02208, doi:10.1029/2007JA012411. Fälthammar, C.-G. (1965), Effects of Time-Dependent Electric Fields on Geomagnetically Trapped Radiation, J. Geophys. Res., 70(11), 2503-2516, doi:10.1029/JZ070i011p02503. Li, X., I. Roth, M. Temerin, J. R. Wygant, M. K. Hudson, and J. B. Blake (1993), Simulation of the prompt energization and transport of radiation belt particles during the March 24, 1991 SSC, textit{Geophys. Res. Lett., 20}(22), 2423-2426, doi:10.1029/93GL02701. Ukhorskiy, A. Y., B. J. Anderson, K. Takahashi, and N. A. Tsyganenko (2006), Impact of ULF oscillations in solar wind dynamic pressure on the outer radiation belt electrons, textit{Geophys. Res. Lett., 33}(6), L06111, doi:10.1029/2005GL024380.

The NASA-sponsored Maryland center for hypersonic education and research

Science.gov (United States)

Lewis, Mark J.; Gupta, Ashwani K.

1995-01-01

The Office of Aeronautics of the National Aeronautics and Space Administration has established a program to support university programs in the field of hypersonic flight. Beginning in the fall of 1993, three universities, including the University of Maryland at College Park, were selected to participate in this activity. The program at the University of Maryland includes faculty in the Department of Aerospace Engineering and Department of Mechanical Engineering, and provides a multidisciplinary environment for graduate and undergraduate students to study and conduct research in the field of hypersonic flight. Ongoing projects cover the range of applications from cruisers through transatmospheric and reentry vehicles. Research activities, focused on propulsion, fluid dynamics, inverse design, and vehicle optimization and integration, are conducted in conjuntion with industrial partners and government laboratories.

Downstream Effects on Orbiter Leeside Flow Separation for Hypersonic Flows

Science.gov (United States)

Buck, Gregory M.; Pulsonetti, Maria V.; Weilmuenster, K. James

2005-01-01

Discrepancies between experiment and computation for shuttle leeside flow separation, which came to light in the Columbia accident investigation, are resolved. Tests were run in the Langley Research Center 20-Inch Hypersonic CF4 Tunnel with a baseline orbiter model and two extended trailing edge models. The extended trailing edges altered the wing leeside separation lines, moving the lines toward the fuselage, proving that wing trailing edge modeling does affect the orbiter leeside flow. Computations were then made with a wake grid. These calculations more closely matched baseline experiments. Thus, the present findings demonstrate that it is imperative to include the wake flow domain in CFD calculations in order to accurately predict leeside flow separation for hypersonic vehicles at high angles of attack.

Examination of uniform momentum zones in hypersonic turbulent boundary layers

Science.gov (United States)

Williams, Owen; Helm, Clara; Martin, Pino

2017-11-01

The presence of uniform momentum zones (UMZs) separated by regions of high shear is now well-established in incompressible flows, with the mean number of such zones increasing in a log-linear fashion with Reynolds number. While known to be present in supersonic and hypersonic boundary layers, the properties of these UMZs and the appropriate Reynolds number for comparison with incompressible results have not previously been investigated. A large, previously published DNS database of hypersonic boundary layers is used in this investigation, with Mach numbers up to 12 and wall temperatures from cold to adiabatic, resulting in a wide range of outer layer Reynolds numbers. UMZs are examined using a range of parameters in both conventional inner and semi-local scalings, and Reynolds number trends examined.

Hypersonic modulation of light in three-dimensional photonic and phononic band-gap materials.

Science.gov (United States)

Akimov, A V; Tanaka, Y; Pevtsov, A B; Kaplan, S F; Golubev, V G; Tamura, S; Yakovlev, D R; Bayer, M

2008-07-18

The elastic coupling between the a-SiO2 spheres composing opal films brings forth three-dimensional periodic structures which besides a photonic stop band are predicted to also exhibit complete phononic band gaps. The influence of elastic crystal vibrations on the photonic band structure has been studied by injection of coherent hypersonic wave packets generated in a metal transducer by subpicosecond laser pulses. These studies show that light with energies close to the photonic band gap can be efficiently modulated by hypersonic waves.

Effect of surface roughness on the heating rates of large-angled hypersonic blunt cones

Science.gov (United States)

Irimpan, Kiran Joy; Menezes, Viren

2018-03-01

Surface-roughness caused by the residue of an ablative Thermal Protection System (TPS) can alter the turbulence level and surface heating rates on a hypersonic re-entry capsule. Large-scale surface-roughness that could represent an ablated TPS, was introduced over the forebody of a 120° apex angle blunt cone, in order to test for its influence on surface heating rates in a hypersonic freestream of Mach 8.8. The surface heat transfer rates measured on smooth and roughened models under the same freestream conditions were compared. The hypersonic flow-fields of the smooth and rough-surfaced models were visualized to analyse the flow physics. Qualitative numerical simulations and pressure measurements were carried out to have an insight into the high-speed flow physics. Experimental observations under moderate Reynolds numbers indicated a delayed transition and an overall reduction of 17-46% in surface heating rates on the roughened model.

Engineering method for aero-propulsive characteristics at hypersonic Mach numbers

Science.gov (United States)

Goradia, Suresh; Torres, Abel O.; Stack, Sharon H.; Everhart, Joel L.

1991-01-01

An engineering method has been developed for the rapid analysis of external aerodynamics and propulsive performance characteristics of airbreathing vehicles at hypersonic Mach numbers. This method, based on the theory of characteristics, has been developed to analyze fuselage-wing body combinations and body flaps with blunt or sharp leading/trailing edges. Arbitrary ratio of specific heat for the flowing medium can be specified in the program. Furthermore, the capability exists in the code to compute the inviscid inlet mass capture and momentum flux. The method is under development for computations of pressure distribution, and flow characteristics in the inlet, along with the effect of viscosity. Correlative studies have been performed for representative hypersonic configurations using the current method. The results of these correlations for various aerodynamics parameters are encouraging.

Analysis of Windward Side Hypersonic Boundary Layer Transition on Blunted Cones at Angle of Attack

Science.gov (United States)

2017-01-09

correlated with PSE/LST N-Factors. 15. SUBJECT TERMS boundary layer transition, hypersonic, ground test 16. SECURITY CLASSIFICATION OF: 17. LIMITATION ...Maccoll) solution e condition at boundary layer edge w condition at wall, viscous ∞ condition in freestream Conventions LST Linear Stability Theory PSE...STATES AIR FORCE AFRL-RQ-WP-TP-2017-0169 ANALYSIS OF WINDWARD SIDE HYPERSONIC BOUNDARY LAYER TRANSITION ON BLUNTED CONES AT ANGLE OF ATTACK Roger

An engineering code to analyze hypersonic thermal management systems

Science.gov (United States)

Vangriethuysen, Valerie J.; Wallace, Clark E.

1993-01-01

Thermal loads on current and future aircraft are increasing and as a result are stressing the energy collection, control, and dissipation capabilities of current thermal management systems and technology. The thermal loads for hypersonic vehicles will be no exception. In fact, with their projected high heat loads and fluxes, hypersonic vehicles are a prime example of systems that will require thermal management systems (TMS) that have been optimized and integrated with the entire vehicle to the maximum extent possible during the initial design stages. This will not only be to meet operational requirements, but also to fulfill weight and performance constraints in order for the vehicle to takeoff and complete its mission successfully. To meet this challenge, the TMS can no longer be two or more entirely independent systems, nor can thermal management be an after thought in the design process, the typical pervasive approach in the past. Instead, a TMS that was integrated throughout the entire vehicle and subsequently optimized will be required. To accomplish this, a method that iteratively optimizes the TMS throughout the vehicle will not only be highly desirable, but advantageous in order to reduce the manhours normally required to conduct the necessary tradeoff studies and comparisons. A thermal management engineering computer code that is under development and being managed at Wright Laboratory, Wright-Patterson AFB, is discussed. The primary goal of the code is to aid in the development of a hypersonic vehicle TMS that has been optimized and integrated on a total vehicle basis.

Supersonic Combustion of Hydrogen Jets System in Hypersonic Stream

International Nuclear Information System (INIS)

Zhapbasbaev, U.K.; Makashev, E.P.

2003-01-01

The data of calculated theoretical investigations of diffusive combustion of plane supersonic hydrogen jets in hypersonic stream received with Navier-Stokes parabola equations closed by one-para metrical (k-l) model of turbulence and multiply staged mechanism of hydrogen oxidation are given. Combustion mechanisms depending on the operating parameters are discussing. The influences of air stream composition and ways off fuel feed to the length of ignition delay and level quantity of hydrogen bum-out have been defined. The calculated theoretical results of investigations permit to make the next conclusions: 1. The diffusive combustion of the system of plane supersonic hydrogen jets in hypersonic flow happens in the cellular structures with alternation zones of intensive running of chemical reactions with their inhibition zones. 2. Gas dynamic and heat Mach waves cause a large - scale viscous formation intensifying mixing of fuel with oxidizer. 3. The system ignition of plane supersonic hydrogen jets in hypersonic airy co-flow happens with the formation of normal flame front of hydrogen airy mixture with transition to the diffusive combustion. 4. The presence of active particles in the flow composition initiates the ignition of hydrogen - airy mixture, provides the intensive running of chemical reactions and shortens the length of ignition delay. 5. The supersonic combustion of hydrogel-airy mixture is characterized by two zones: the intensive chemical reactions with an active energy heat release is occurring in the first zone and in the second - a slow hydrogen combustion limited by the mixing of fuel with oxidizer. (author)

Multiscale Computational Analysis of Nitrogen and Oxygen Gas-Phase Thermochemistry in Hypersonic Flows

Science.gov (United States)

Bender, Jason D.

Understanding hypersonic aerodynamics is important for the design of next-generation aerospace vehicles for space exploration, national security, and other applications. Ground-level experimental studies of hypersonic flows are difficult and expensive; thus, computational science plays a crucial role in this field. Computational fluid dynamics (CFD) simulations of extremely high-speed flows require models of chemical and thermal nonequilibrium processes, such as dissociation of diatomic molecules and vibrational energy relaxation. Current models are outdated and inadequate for advanced applications. We describe a multiscale computational study of gas-phase thermochemical processes in hypersonic flows, starting at the atomic scale and building systematically up to the continuum scale. The project was part of a larger effort centered on collaborations between aerospace scientists and computational chemists. We discuss the construction of potential energy surfaces for the N4, N2O2, and O4 systems, focusing especially on the multi-dimensional fitting problem. A new local fitting method named L-IMLS-G2 is presented and compared with a global fitting method. Then, we describe the theory of the quasiclassical trajectory (QCT) approach for modeling molecular collisions. We explain how we implemented the approach in a new parallel code for high-performance computing platforms. Results from billions of QCT simulations of high-energy N2 + N2, N2 + N, and N2 + O2 collisions are reported and analyzed. Reaction rate constants are calculated and sets of reactive trajectories are characterized at both thermal equilibrium and nonequilibrium conditions. The data shed light on fundamental mechanisms of dissociation and exchange reactions -- and their coupling to internal energy transfer processes -- in thermal environments typical of hypersonic flows. We discuss how the outcomes of this investigation and other related studies lay a rigorous foundation for new macroscopic models for

Modeling and simulations of radiative blast wave driven Rayleigh-Taylor instability experiments

Science.gov (United States)

Shimony, Assaf; Huntington, Channing M.; Trantham, Matthew; Malamud, Guy; Elbaz, Yonatan; Kuranz, Carolyn C.; Drake, R. Paul; Shvarts, Dov

2017-10-01

Recent experiments at the National Ignition Facility measured the growth of Rayleigh-Taylor RT instabilities driven by radiative blast waves, relevant to astrophysics and other HEDP systems. We constructed a new Buoyancy-Drag (BD) model, which accounts for the ablation effect on both bubble and spike. This ablation effect is accounted for by using the potential flow model ]Oron et al PoP 1998], adding another term to the classical BD formalism: βDuA / u , where β the Takabe constant, D the drag term, uA the ablation velocity and uthe instability growth velocity. The model results are compared with the results of experiments and 2D simulations using the CRASH code, with nominal radiation or reduced foam opacity (by a factor of 1000). The ablation constant of the model, βb / s, for the bubble and for the spike fronts, are calibrated using the results of the radiative shock experiments. This work is funded by the Lawrence Livermore National Laboratory under subcontract B614207, and was performed under the auspices of the U.S. Department of Energy by Lawrence Livermore National Laboratory under Contract No. DE-AC52-07NA27344.

Solution-Space Screening of a Hypersonic Endurance Demonstrator

Science.gov (United States)

Chudoba, Bernd; Coleman, Gary; Oza, Amit; Gonzalez, Lex; Czysz, Paul

2012-01-01

This report documents a parametric sizing study performed to develop a program strategy for research and development and procurement of a feasible next-generation hypersonic air-breathing endurance demonstrator. Overall project focus has been on complementing technical and managerial decision-making during the earliest conceptual design phase towards minimization of operational, technical, and managerial risks.

Wind-Tunnel Balance Characterization for Hypersonic Research Applications

Science.gov (United States)

Lynn, Keith C.; Commo, Sean A.; Parker, Peter A.

2012-01-01

Wind-tunnel research was recently conducted at the NASA Langley Research Center s 31-Inch Mach 10 Hypersonic Facility in support of the Mars Science Laboratory s aerodynamic program. Researchers were interested in understanding the interaction between the freestream flow and the reaction control system onboard the entry vehicle. A five-component balance, designed for hypersonic testing with pressurized flow-through capability, was used. In addition to the aerodynamic forces, the balance was exposed to both thermal gradients and varying internal cavity pressures. Historically, the effect of these environmental conditions on the response of the balance have not been fully characterized due to the limitations in the calibration facilities. Through statistical design of experiments, thermal and pressure effects were strategically and efficiently integrated into the calibration of the balance. As a result of this new approach, researchers were able to use the balance continuously throughout the wide range of temperatures and pressures and obtain real-time results. Although this work focused on a specific application, the methodology shown can be applied more generally to any force measurement system calibration.

Numerical analysis of hypersonic turbulent film cooling flows

Science.gov (United States)

Chen, Y. S.; Chen, C. P.; Wei, H.

1992-01-01

As a building block, numerical capabilities for predicting heat flux and turbulent flowfields of hypersonic vehicles require extensive model validations. Computational procedures for calculating turbulent flows and heat fluxes for supersonic film cooling with parallel slot injections are described in this study. Two injectant mass flow rates with matched and unmatched pressure conditions using the database of Holden et al. (1990) are considered. To avoid uncertainties associated with the boundary conditions in testing turbulence models, detailed three-dimensional flowfields of the injection nozzle were calculated. Two computational fluid dynamics codes, GASP and FDNS, with the algebraic Baldwin-Lomax and k-epsilon models with compressibility corrections were used. It was found that the B-L model which resolves near-wall viscous sublayer is very sensitive to the inlet boundary conditions at the nozzle exit face. The k-epsilon models with improved wall functions are less sensitive to the inlet boundary conditions. The testings show that compressibility corrections are necessary for the k-epsilon model to realistically predict the heat fluxes of the hypersonic film cooling problems.

Robust stabilization control based on guardian maps theory for a longitudinal model of hypersonic vehicle.

Science.gov (United States)

Liu, Yanbin; Liu, Mengying; Sun, Peihua

2014-01-01

A typical model of hypersonic vehicle has the complicated dynamics such as the unstable states, the nonminimum phases, and the strong coupling input-output relations. As a result, designing a robust stabilization controller is essential to implement the anticipated tasks. This paper presents a robust stabilization controller based on the guardian maps theory for hypersonic vehicle. First, the guardian maps theories are provided to explain the constraint relations between the open subsets of complex plane and the eigenvalues of the state matrix of closed-loop control system. Then, a general control structure in relation to the guardian maps theories is proposed to achieve the respected design demands. Furthermore, the robust stabilization control law depending on the given general control structure is designed for the longitudinal model of hypersonic vehicle. Finally, a simulation example is provided to verify the effectiveness of the proposed methods.

Potential theory of radiation

International Nuclear Information System (INIS)

Chiu, Hueihuang.

1989-01-01

A theoretical method is being developed by which the structure of a radiation field can be predicted by a radiation potential theory, similar to a classical potential theory. The introduction of a scalar potential is justified on the grounds that the spectral intensity vector is irrotational. The vector is also solenoidal in the limits of a radiation field in complete radiative equilibrium or in a vacuum. This method provides an exact, elliptic type equation that will upgrade the accuracy and the efficiency of the current CFD programs required for the prediction of radiation and flow fields. A number of interesting results emerge from the present study. First, a steady state radiation field exhibits an optically modulated inverse square law distribution character. Secondly, the unsteady radiation field is structured with two conjugate scalar potentials. Each is governed by a Klein-Gordon equation with a frictional force and a restoring force. This steady potential field structure and the propagation of radiation potentials are consistent with the well known results of classical electromagnetic theory. The extension of the radiation potential theory for spray combustion and hypersonic flow is also recommended

Preliminary Studies on Aerodynamic Control with Direct Current Discharge at Hypersonic Speed

Science.gov (United States)

Watanabe, Yasumasa; Takama, Yoshiki; Imamura, Osamu; Watanuki, Tadaharu; Suzuki, Kojiro

A new idea of an aerodynamic control device for hypersonic vehicles using plasma discharges is presented. The effect of DC plasma discharge on a hypersonic flow is examined with both experiments and CFD analyses. It is revealed that the surface pressure upstream of plasma area significantly increases, which would be preferable in realizing a new aerodynamic control devices. Such pressure rise is also observed in the result of analyses of the Navier-Stokes equations with energy addition that simulates the Joule heating of a plasma discharge. It is revealed that the pressure rise due to the existence of the plasma discharge can be qualitatively explained as an effect of Joule heating.

Accelerator-driven X-ray Sources

Energy Technology Data Exchange (ETDEWEB)

Nguyen, Dinh Cong [Los Alamos National Lab. (LANL), Los Alamos, NM (United States)

2015-11-09

After an introduction which mentions x-ray tubes and storage rings and gives a brief review of special relativity, the subject is treated under the following topics and subtopics: synchrotron radiation (bending magnet radiation, wiggler radiation, undulator radiation, brightness and brilliance definition, synchrotron radiation facilities), x-ray free-electron lasers (linac-driven X-ray FEL, FEL interactions, self-amplified spontaneous emission (SASE), SASE self-seeding, fourth-generation light source facilities), and other X-ray sources (energy recovery linacs, Inverse Compton scattering, laser wakefield accelerator driven X-ray sources. In summary, accelerator-based light sources cover the entire electromagnetic spectrum. Synchrotron radiation (bending magnet, wiggler and undulator radiation) has unique properties that can be tailored to the users’ needs: bending magnet and wiggler radiation is broadband, undulator radiation has narrow spectral lines. X-ray FELs are the brightest coherent X-ray sources with high photon flux, femtosecond pulses, full transverse coherence, partial temporal coherence (SASE), and narrow spectral lines with seeding techniques. New developments in electron accelerators and radiation production can potentially lead to more compact sources of coherent X-rays.

Study of the coupling between real gas effects and rarefied effects on hypersonic aerodynamics

Science.gov (United States)

Chen, Song; Hu, Yuan; Sun, Quanhua

2012-11-01

Hypersonic vehicles travel across the atmosphere at very high speed, and the surrounding gas experiences complicated physical and chemical processes. These processes produce real gas effects at high temperature and rarefied gas effects at high altitude where the two effects are coupled through molecular collisions. In this study, we aim to identify the individual real gas and rarefied gas effects by simulating hypersonic flow over a 2D cylinder, a sphere and a blunted cone using a continuum-based CFD approach and the direct simulation Monte Carlo method. It is found that physical processes such as vibrational excitation and chemical reaction will reduce significantly the shock stand-off distance and flow temperature for flows having small Knudsen number. The calculated skin friction and surface heat flux will decrease when the real gas effects are considered in simulations. The trend, however, gets weakened as the Knudsen number increases. It is concluded that the rarefied gas effects weaken the real gas effects on hypersonic flows.

Non-gray gas radiation effect on mixed convection in lid driven square cavity

Energy Technology Data Exchange (ETDEWEB)

Cherifi, Mohammed, E-mail: production1998@yahoo.fr; Benbrik, Abderrahmane, E-mail: abenbrik@umbb.dz; Laouar-Meftah, Siham, E-mail: laouarmeftah@gmail.com [M’Hamed Bougara University, Faculty of Hydrocarbons and Chemistry, 35000 Boumerdes (Algeria); Lemonnier, Denis, E-mail: denis.lemonnier@ensma.fr [Institut Pprime, CNRS, ENSMA, University of Poitiers, Poitiers Futuroscope (France)

2016-06-02

A numerical study is performed to investigate the effect of non-gray radiation on mixed convection in a vertical two sided lid driven square cavity filled with air-H{sub 2}O-CO{sub 2} gas mixture. The vertical moving walls of the enclosure are maintained at two different but uniform temperatures. The horizontal walls are thermally insulated and considered as adiabatic walls. The governing differential equations are solved by a finite-volume method and the SIMPLE algorithm was adopted to solve the pressure–velocity coupling. The radiative transfer equation (RTE) is solved by the discrete ordinates method (DOM). The spectral line weighted sum of gray gases model (SLW) is used to account for non-gray radiation properties. Simulations are performed in configurations where thermal and shear forces induce cooperating buoyancy forces. Streamlines, isotherms, and Nusselt number are analyzed for three different values of Richardson’s number (from 0.1 to 10) and by considering three different medium (transparent medium, gray medium using the Planck mean absorption coefficient, and non-gray medium assumption).

Quantifying Non-Equilibrium in Hypersonic Flows Using Entropy Generation

Science.gov (United States)

2007-03-01

do this, two experimental cases performed at the Calspan- University of Buffalo Research Center ( CUBRC ) were modeled using Navier-Stokes based CFD...data provided by the CUBRC hypersonic wind tunnel facility (Holden and Wadhams, 2004). The wall data in Figure 9 and Figure 10 reveals some difference

Advanced Metal Rubber Sensors for Hypersonic Decelerator Entry Systems, Phase I

Data.gov (United States)

National Aeronautics and Space Administration — NanoSonic proposes to design and develop light-weight, low-modulus, and durable Metal Rubber™ sensors for aeroelastic analysis of Hypersonic Decelerator Entry...

Investigation of piloting aids for manual control of hypersonic maneuvers

Science.gov (United States)

Raney, David L.; Phillips, Michael R.; Person, Lee H., Jr.

1995-01-01

An investigation of piloting aids designed to provide precise maneuver control for an air-breathing hypersonic vehicle is described. Stringent constraints and nonintuitive high-speed flight effects associated with maneuvering in the hypersonic regime raise the question of whether manual control of such a vehicle should even be considered. The objectives of this research were to determine the extent of manual control that is desirable for a vehicle maneuvering in this regime and to identify the form of aids that must be supplied to the pilot to make such control feasible. A piloted real-time motion-based simulation of a hypersonic vehicle concept was used for this study, and the investigation focused on a single representative cruise turn maneuver. Piloting aids, which consisted of an auto throttle, throttle director, autopilot, flight director, and two head-up display configurations, were developed and evaluated. Two longitudinal control response types consisting of a rate-command/attitude-hold system and a load factor-rate/load-factor-hold system were also compared. The complete set of piloting aids, which consisted of the autothrottle, throttle director, and flight director, improved the average Cooper-Harper flying qualities ratings from 8 to 2.6, even though identical inner-loop stability and control augmentation was provided in all cases. The flight director was determined to be the most critical of these aids, and the cruise turn maneuver was unachievable to adequate performance specifications in the absence of this flight director.

Drag Reduction by Laser-Plasma Energy Addition in Hypersonic Flow

International Nuclear Information System (INIS)

Oliveira, A. C.; Minucci, M. A. S.; Toro, P. G. P.; Chanes, J. B. Jr; Myrabo, L. N.

2008-01-01

An experimental study was conducted to investigate the drag reduction by laser-plasma energy addition in a low density Mach 7 hypersonic flow. The experiments were conducted in a shock tunnel and the optical beam of a high power pulsed CO 2 TEA laser operating with 7 J of energy and 30 MW peak power was focused to generate the plasma upstream of a hemispherical model installed in the tunnel test section. The non-intrusive schlieren optical technique was used to visualize the effects of the energy addition to hypersonic flow, from the plasma generation until the mitigation of the shock wave profile over the model surface. Aside the optical technique, a piezoelectric pressure transducer was used to measure the impact pressure at stagnation point of the hemispherical model and the pressure reduction could be observed

The steady state solutions of radiatively driven stellar winds for a non-Sobolev, pure absorption model

International Nuclear Information System (INIS)

Poe, C.H.; Owocki, S.P.; Castor, J.I.

1990-01-01

The steady state solution topology for absorption line-driven flows is investigated for the condition that the Sobolev approximation is not used to compute the line force. The solution topology near the sonic point is of the nodal type with two positive slope solutions. The shallower of these slopes applies to reasonable lower boundary conditions and realistic ion thermal speed v(th) and to the Sobolev limit of zero of the usual Castor, Abbott, and Klein model. At finite v(th), this solution consists of a family of very similar solutions converging on the sonic point. It is concluded that a non-Sobolev, absorption line-driven flow with a realistic values of v(th) has no uniquely defined steady state. To the extent that a pure absorption model of the outflow of stellar winds is applicable, radiatively driven winds should be intrinsically variable. 34 refs

Computation of hypersonic axisymmetric flows of equilibrium gas over blunt bodies

International Nuclear Information System (INIS)

Hejranfar, K.; Esfahanian, V.; Moghadam, R.K.

2005-01-01

An appropriate combination of the thin-layer Navier-Stokes (TLNS) and parabolized Navier-Stokes (PNS) solvers is used to accurately and efficiently compute hypersonic flowfields of equilibrium air around blunt-body configurations. The TLNS equations are solved in the nose region to provide the initial data plane needed for the solution of the PNS equations. Then the PNS equations are employed to efficiently compute the flowfield for the afterbody region by using a space marching procedure. Both the TLNS and the PNS equations are numerically solved by using the implicit non-iterative finite-difference algorithm of Beam and Warming. A shock fitting technique is used in both the TLNS and PNS codes to obtain accurate solution in the vicinity of the shock. To validate the results of the developed TLNS code, hypersonic laminar flow over a sphere at Mach number of 11.26 is computed. To demonstrate the accuracy and efficiency of using the present TLNS-PNS methodology, the computations are performed for hypersonic flow over 5 o long slender blunt cone at Mach number of 19.25. The results of these computations are found to be in good agreement with available numerical and experimental data. The effects of real gas on the flowfield characteristics are also studied in both the TLNS and PNS solutions. (author)

X-43A Hypersonic Experimental Vehicle - Artist Concept in Flight

Science.gov (United States)

1999-01-01

An artist's conception of the X-43A Hypersonic Experimental Vehicle, or 'Hyper-X' in flight. The X-43A was developed to flight test a dual-mode ramjet/scramjet propulsion system at speeds from Mach 7 up to Mach 10 (7 to 10 times the speed of sound, which varies with temperature and altitude). Hyper-X, the flight vehicle for which is designated as X-43A, is an experimental flight-research program seeking to demonstrate airframe-integrated, 'air-breathing' engine technologies that promise to increase payload capacity for future vehicles, including hypersonic aircraft (faster than Mach 5) and reusable space launchers. This multiyear program is currently underway at NASA Dryden Flight Research Center, Edwards, California. The Hyper-X schedule calls for its first flight later this year (2000). Hyper-X is a joint program, with Dryden sharing responsibility with NASA's Langley Research Center, Hampton, Virginia. Dryden's primary role is to fly three unpiloted X-43A research vehicles to validate engine technologies and hypersonic design tools as well as the hypersonic test facility at Langley. Langley manages the program and leads the technology development effort. The Hyper-X Program seeks to significantly expand the speed boundaries of air-breathing propulsion by being the first aircraft to demonstrate an airframe-integrated, scramjet-powered free flight. Scramjets (supersonic-combustion ramjets) are ramjet engines in which the airflow through the whole engine remains supersonic. Scramjet technology is challenging because only limited testing can be performed in ground facilities. Long duration, full-scale testing requires flight research. Scramjet engines are air-breathing, capturing their oxygen from the atmosphere. Current spacecraft, such as the Space Shuttle, are rocket powered, so they must carry both fuel and oxygen for propulsion. Scramjet technology-based vehicles need to carry only fuel. By eliminating the need to carry oxygen, future hypersonic vehicles will

Hypersonic Free-Flight Measurement of Aeroshell Forces and Flowfields, Phase I

Data.gov (United States)

National Aeronautics and Space Administration — A Hypersonic Gun Tunnel and laser based high speed imaging systems will be used to generate a unique, free flight, aerodynamic data base of potential Mars aeroshell...

Experimental Studies of Shock Interaction Phenomena Associated with Hypersonic Airbreathing Propulsion

National Research Council Canada - National Science Library

Holden, Michael

2001-01-01

... and double cone configurations in hypersonic flow. In the best Navier-Stokes solutions the structure and density of the flowfield was captured exactly over both the hollow cylinder/flare and double cone models...

A Laser-Based Diagnostic Suite for Hypersonic Test Facilities, Phase I

Data.gov (United States)

National Aeronautics and Space Administration — In this SBIR effort, Los Gatos Research (LGR) proposes to develop a suite of laser-based diagnostics for the study of reactive and non-reactive hypersonic flows....

Plasma parameters and electromagnetic forces induced by the magneto hydro dynamic interaction in a hypersonic argon flow experiment

International Nuclear Information System (INIS)

Cristofolini, Andrea; Neretti, Gabriele; Borghi, Carlo A.

2012-01-01

This work proposes an experimental analysis on the magneto hydro dynamic (MHD) interaction induced by a magnetic test body immersed into a hypersonic argon flow. The characteristic plasma parameters are measured. They are related to the voltages arising in the Hall direction and to the variation of the fluid dynamic properties induced by the interaction. The tests have been performed in a hypersonic wind tunnel at Mach 6 and Mach 15. The plasma parameters are measured in the stagnation region in front of the nozzle of the wind tunnel and in the free stream region at the nozzle exit. The test body has a conical shape with the cone axis in the gas flow direction and the cone vertex against the flow. It is placed at the nozzle exit and is equipped with three permanent magnets. In the configuration adopted, the Faraday current flows in a closed loop completely immersed into the plasma of the shock layer. The electric field and the pressure variation due to MHD interaction have been measured on the test body walls. Microwave adsorption measurements have been used for the determination of the electron number density and the electron collision frequency. Continuum recombination radiation and line radiation emissions have been detected. The electron temperature has been determined by means of the spectroscopic data by using different methods. The electron number density has been also determined by means of the Stark broadening of H α and the H β lines. Optical imaging has been utilized to visualize the pattern of the electric current distribution in the shock layer around the test body. The experiments show a considerable effect of the electromagnetic forces produced by the MHD interaction acting on the plasma flow around the test body. A comparison of the experimental data with simulation results shows a good agreement.

Experimental And Numerical Investigation Of Aerothermal Characteristics Of The IXV Hypersonic Vehicle

Science.gov (United States)

Paris, S.; Charbonnier, D.; Tran, D.

2011-05-01

The main results of the aerothermodynamic hypersonic characterization of Intermediate eXperimental Vehicle (IXV), by means of both CFD simulations and wind tunnel measurements, have been reported and analyzed. In the framework of ESA FLPP Program, the VKI (Von Karman Institute) was in charge of an experimental test campaign for the consolidation of the aerothermal database in cold hypersonic regime. The tests campaign has been carried out at VKI Free Piston Longshot wind tunnel at mach 14. The numerical simulations have been performed for VKI wind tunnel conditions by CFSE with the in-house NSMB flow solver (Navier-Stokes Multi-Blocks 3D), the goal being to support the procedure of extrapolation-to-flight of the measurements and the general aerothermal characterization. Laminar, transitional and fully turbulent flows have been computed, with air considered as an ideal gas, for the wind tunnel tests numerical rebuilding. A detailed comparison of all measured and predicted hypersonic relevant phenomena and parameters (surface pressure and heat flux) is reported in the paper, together with a detailed description of configuration, freestream conditions, model attitude effects and flap deflection effect. The detailed analyze of the experimental and numerical data gives information on the nature of the flow on the body and on the flaps for the most critical configuration

Real-Gas Correction Factors for Hypersonic Flow Parameters in Helium

Science.gov (United States)

Erickson, Wayne D.

1960-01-01

The real-gas hypersonic flow parameters for helium have been calculated for stagnation temperatures from 0 F to 600 F and stagnation pressures up to 6,000 pounds per square inch absolute. The results of these calculations are presented in the form of simple correction factors which must be applied to the tabulated ideal-gas parameters. It has been shown that the deviations from the ideal-gas law which exist at high pressures may cause a corresponding significant error in the hypersonic flow parameters when calculated as an ideal gas. For example the ratio of the free-stream static to stagnation pressure as calculated from the thermodynamic properties of helium for a stagnation temperature of 80 F and pressure of 4,000 pounds per square inch absolute was found to be approximately 13 percent greater than that determined from the ideal-gas tabulation with a specific heat ratio of 5/3.

Application of CFD to a generic hypersonic flight research study

Science.gov (United States)

Green, Michael J.; Lawrence, Scott L.; Dilley, Arthur D.; Hawkins, Richard W.; Walker, Mary M.; Oberkampf, William L.

1993-01-01

Computational analyses have been performed for the initial assessment of flight research vehicle concepts that satisfy requirements for potential hypersonic experiments. Results were obtained from independent analyses at NASA Ames, NASA Langley, and Sandia National Labs, using sophisticated time-dependent Navier-Stokes and parabolized Navier-Stokes methods. Careful study of a common problem consisting of hypersonic flow past a slightly blunted conical forebody was undertaken to estimate the level of uncertainty in the computed results, and to assess the capabilities of current computational methods for predicting boundary-layer transition onset. Results of this study in terms of surface pressure and heat transfer comparisons, as well as comparisons of boundary-layer edge quantities and flow-field profiles are presented here. Sensitivities to grid and gas model are discussed. Finally, representative results are presented relating to the use of Computational Fluid Dynamics in the vehicle design and the integration/support of potential experiments.

Effective high-order solver with thermally perfect gas model for hypersonic heating prediction

International Nuclear Information System (INIS)

Jiang, Zhenhua; Yan, Chao; Yu, Jian; Qu, Feng; Ma, Libin

2016-01-01

Highlights: • Design proper numerical flux for thermally perfect gas. • Line-implicit LUSGS enhances efficiency without extra memory consumption. • Develop unified framework for both second-order MUSCL and fifth-order WENO. • The designed gas model can be applied to much wider temperature range. - Abstract: Effective high-order solver based on the model of thermally perfect gas has been developed for hypersonic heat transfer computation. The technique of polynomial curve fit coupling to thermodynamics equation is suggested to establish the current model and particular attention has been paid to the design of proper numerical flux for thermally perfect gas. We present procedures that unify five-order WENO (Weighted Essentially Non-Oscillatory) scheme in the existing second-order finite volume framework and a line-implicit method that improves the computational efficiency without increasing memory consumption. A variety of hypersonic viscous flows are performed to examine the capability of the resulted high order thermally perfect gas solver. Numerical results demonstrate its superior performance compared to low-order calorically perfect gas method and indicate its potential application to hypersonic heating predictions for real-life problem.

Lithium ion beam driven hohlraums for PBFA II

International Nuclear Information System (INIS)

Dukart, R.J.

1994-01-01

In our light ion inertial confinement fusion (ICF) program, fusion capsules are driven with an intense x-ray radiation field produced when an intense beam of ions penetrates a radiation case and deposits energy in a foam x-ray conversion region. A first step in the program is to generate and measure these intense fields on the Particle Beam Fusion Accelerator II (PBFA II). Our goal is to generate a 100-eV radiation temperature in lithium ion beam driven hohlraums, the radiation environment which will provide the initial drive temperature for ion beam driven implosion systems designed to achieve high gain. In this paper, we describe the design of such hohlraum targets and their predicted performance on PBFA II as we provide increasing ion beam intensities

SiC Matrix Composites for High Temperature Hypersonic Vehicle Applications, Phase I

Data.gov (United States)

National Aeronautics and Space Administration — Durable high temperature materials are required for hypersonic engine and structural thermal protection systems. In particular, 2700ºF or greater capable structural...

Calculation of State Specific Rate Coefficients for Non-Equilibrium Hypersonics Applications: from H(Psi) = E(Psi) to k(T) = A *exp(-E(sub a)/RT)

Science.gov (United States)

Jaffe, Richard; Schwenke, David; Chaban, Galina; Panesi, Marco

2014-01-01

Development of High-Fidelity Physics-Based Models to describe hypersonic flight through the atmospheres of Earth and Mars is underway at NASA Ames Research Center. The goal is to construct chemistry models of the collisional and radiative processes that occur in the bow shock and boundary layers of spacecraft during atmospheric entry that are free of empiricism. In this talk I will discuss our philosophy and describe some of our progress. Topics to be covered include thermochemistry, internal energy relaxation, collisional dissociation and radiative emission and absorption. For this work we start by solving the Schrodinger equation to obtain accurate interaction potentials and radiative properties. Then we invoke classical mechanics to compute state-specific heavy particle collision cross sections and reaction rate coefficients. Finally, phenomenological rate coefficients and relaxation times are determined from master equation solutions.

Numerical Investigation of Heat Transfer with Thermal Radiation in an Enclosure in Case of Buoyancy Driven Flow

Directory of Open Access Journals (Sweden)

Christoph Hochenauer

2014-08-01

Full Text Available The purpose of this paper is to investigate state of the art approaches and their accuracy to compute heat transfer including radiation inside a closed cavity whereas buoyancy is the only driving force. This research is the first step of an all-embracing study dealing with underhood airflow and thermal management of vehicles. Computational fluid dynamic (CFD simulation results of buoyancy driven flow inside a simplified engine compartment are compared to experimentally gained values. The test rig imitates idle condition without any working fan. Thus, the airflow is only driven by natural convection. A conventional method used for these applications is to compute the convective heat transfer coefficient and air temperature using CFD and calculate the wall temperature separately by performing a thermal analysis. The final solution results from coupling two different software tools. In this paper thermal conditions inside the enclosure are computed by the use of CFD only. The impact of the turbulence model as well as the results of various radiation models are analyzed and compared to the experimental data.

Supersymmetry with Radiatively-Driven Naturalness: Implications for WIMP and Axion Searches

Directory of Open Access Journals (Sweden)

Kyu Jung Bae

2015-05-01

Full Text Available By insisting on naturalness in both the electroweak and quantum chromodynamics (QCD sectors of the minimal supersymmetric standard model (MSSM, the portrait for dark matter production is seriously modified from the usual weakly interacting massive particle (WIMP miracle picture. In supersymmetry (SUSY models with radiatively-driven naturalness (radiative natural SUSY or radiative natural SUSY (RNS which include a Dine–Fischler–Srednicki–Zhitnitsky (DFSZ-like solution to the strong charge-conjugation-parity (CP and SUSY \\(\\mu\\ problems, dark matter is expected to be an admixture of both axions and higgsino-like WIMPs. The WIMP/axion abundance calculation requires simultaneous solution of a set of coupled Boltzmann equations which describe quasi-stable axinos and saxions. In most of parameter space, axions make up the dominant contribution of dark matter although regions of WIMP dominance also occur. We show the allowed range of Peccei-Quinn (PQ scale \\(f_a\\ and compare to the values expected to be probed by the axion dark matter search experiment (ADMX axion detector in the near future. We also show WIMP detection rates, which are suppressed from usual expectations, because now WIMPs comprise only a fraction of the total dark matter. Nonetheless, ton-scale noble liquid detectors should be able to probe the entirety of RNS parameter space. Indirect WIMP detection rates are less propitious since they are reduced by the square of the depleted WIMP abundance.

Fault-tolerant control with mixed aerodynamic surfaces and RCS jets for hypersonic reentry vehicles

Directory of Open Access Journals (Sweden)

Jingjing He

2017-04-01

Full Text Available This paper proposes a fault-tolerant strategy for hypersonic reentry vehicles with mixed aerodynamic surfaces and reaction control systems (RCS under external disturbances and subject to actuator faults. Aerodynamic surfaces are treated as the primary actuator in normal situations, and they are driven by a continuous quadratic programming (QP allocator to generate torque commanded by a nonlinear adaptive feedback control law. When aerodynamic surfaces encounter faults, they may not be able to provide sufficient torque as commanded, and RCS jets are activated to augment the aerodynamic surfaces to compensate for insufficient torque. Partial loss of effectiveness and stuck faults are considered in this paper, and observers are designed to detect and identify the faults. Based on the fault identification results, an RCS control allocator using integer linear programming (ILP techniques is designed to determine the optimal combination of activated RCS jets. By treating the RCS control allocator as a quantization element, closed-loop stability with both continuous and quantized inputs is analyzed. Simulation results verify the effectiveness of the proposed method.

Hypersonic Technology Developments with EU Co-Funded Projects

Science.gov (United States)

2010-09-01

and Hypersonic Systems and Technologies Conference, AIAA-2006-8109, 06-09/11 2006, Canberra, Australia. [18] Karl S., Hannemann K., Steelant J. and...Canberra, Australia. [23] Haidn, O., Ciezki, H., Hannemann , K. and Karl., S., Selected Supersonic Combustion Activities at DLR within the European...LAPCAT Project, 2nd European Conference for Aerospace Sciences (EUCASS), July 2007, Brussels, Belgium. [24] Martinez-Schram J. , Karl S., Hannemann K

Molecular-Based Optical Diagnostics for Hypersonic Nonequilibrium Flows

Science.gov (United States)

Danehy, Paul; Bathel, Brett; Johansen, Craig; Winter, Michael; O'Byrne, Sean; Cutler, Andrew

2015-01-01

This presentation package consists of seven different talks rolled up into one. These talks are all invited orals presentations in a special session at the Aviation 2015 conference and represent contributions that were made to a recent AIAA book that will be published entitled 'Hypersonic Nonequilibrium Flows: Fundamentals and Recent Advances'. Slide 5 lists the individual presentations that will be given during the special session.

A model for supersonic and hypersonic impactors for nanoparticles

International Nuclear Information System (INIS)

Abouali, Omid; Ahmadi, Goodarz

2005-01-01

In this study the performance of supersonic and hypersonic impactors for collection efficiency of nanoparticles (in the size range of 2-100 nm) under various operating conditions is analyzed. Axisymmetric forms of the compressible Navier-Stokes and energy equations are solved and the airflow and thermal condition in the impactor are evaluated. A Lagrangian particle trajectory analysis procedure is used and the deposition rates of different size particles under various operating conditions are studied. For dilute particle concentrations, the assumption of one-way interaction is used and the effect of particles on gas flow field is ignored. The importance of drag, lift and Brownian forces on particle motions in supersonic impactors is discussed. Sensitivity of the simulation results to the use of different assumptions for the Cunningham correction coefficient is studied. It is shown that accurate evaluation of the gas mean free path and the Cunningham correction factor is important for accurate simulation of nano-particle transport and deposition in supersonic/hypersonic impactors. The computer simulation results are compared favorably with the available experimental data

Validation of engineering methods for predicting hypersonic vehicle controls forces and moments

Science.gov (United States)

Maughmer, M.; Straussfogel, D.; Long, L.; Ozoroski, L.

1991-01-01

This work examines the ability of the aerodynamic analysis methods contained in an industry standard conceptual design code, the Aerodynamic Preliminary Analysis System (APAS II), to estimate the forces and moments generated through control surface deflections from low subsonic to high hypersonic speeds. Predicted control forces and moments generated by various control effectors are compared with previously published wind-tunnel and flight-test data for three vehicles: the North American X-15, a hypersonic research airplane concept, and the Space Shuttle Orbiter. Qualitative summaries of the results are given for each force and moment coefficient and each control derivative in the various speed ranges. Results show that all predictions of longitudinal stability and control derivatives are acceptable for use at the conceptual design stage.

Experimental results of a Mach 10 conical-flow derived waverider to 14-X hypersonic aerospace vehicle

Directory of Open Access Journals (Sweden)

Tiago Cavalcanti Rolim

2011-05-01

Full Text Available This paper presents a research in the development of the 14-X hypersonic airspace vehicle at Institute for Advanced Studies (IEAv from Department of Science and Aerospace Technology (DCTA of the Brazilian Air Force (FAB. The 14-X project objective is to develop a higher efficient satellite launch alternative, using a Supersonic Combustion Ramjet (SCRAMJET engine and waverider aerodynamics. For this development, the waverider technology is under investigation in Prof. Henry T. Nagamatsu Aerothermodynamics and Hypersonics Laboratory (LHTN, in IEAv/DCTA. The investigation has been conducted through ground test campaigns in Hypersonic Shock Tunnel T3. The 14-X Waverider Vehicle characteristic was verified in shock tunnel T3 where surface static pressures and pitot pressure for Mach number 10 were measured and, using Schlieren photographs Diagnostic Method, it was possible to identify a leading-edge attached shock wave in 14-X lower surface.

Adaptive Command Filtered Integrated Guidance and Control for Hypersonic Vehicle with Magnitude, Rate and Bandwidth Constraints

Directory of Open Access Journals (Sweden)

Wang Liang

2018-01-01

Full Text Available This paper proposes a novel integrated guidance and control (IGC method for hypersonic vehicle in terminal phase. Firstly, the system model is developed with a second order actuator dynamics. Then the back-stepping controller is designed hierarchically with command filters, where the first order command filters are implemented to construct the virtual control input with ideal states predicted by an adaptive estimator, and the nonlinear command filter is designed to produce magnitude, rate and bandwidth limited control surface deflection finally tracked by a terminal sliding mode controller with finite convergence time. Through a series of 6-DOF numerical simulations, it’s indicated that the proposed method successfully cancels out the large aerodynamics coefficient uncertainties and disturbances in hypersonic flight under limited control surface deflection. The contribution of this paper lies in the application and determination of nonlinear integrated design of guidance and control system for hypersonic vehicle.

Thermomechanical response of a cross-ply titanium matrix composite subjected to a generic hypersonic flight profile

International Nuclear Information System (INIS)

Mirdamadi, M.; Johnson, W.S.

1993-01-01

Cross-ply laminate behavior of Ti-15V-3Cr-3AI-3Sn (Ti-15-3) matrix reinforced with continuous silicon-carbide fibers (SCS-6) subjected to a generic hypersonic flight profile was evaluated experimentally and analytically. Thermomechanical fatigue test techniques were developed to conduct a simulation of a generic hypersonic flight profile. A micromechanical analysis was used. The analysis predicts the stress-strain response of the laminate and of the constituents in each ply during thermal and mechanical cycling by using only constituent properties as input. The fiber was modeled as elastic with transverse orthotropic and temperature-dependent properties. The matrix was modeled using a thermoviscoplastic constitutive relation. The fiber transverse modulus was reduced in the analysis to simulate the fiber-matrix interface failure. Excellent correlation was found between measured and predicted laminate stress-strain response due to generic hypersonic flight profile when fiber debonding was modeled

A study of upwind schemes on the laminar hypersonic heating predictions for the reusable space vehicle

Science.gov (United States)

Qu, Feng; Sun, Di; Zuo, Guang

2018-06-01

With the rapid development of the Computational Fluid Dynamics (CFD), Accurate computing hypersonic heating is in a high demand for the design of the new generation reusable space vehicle to conduct deep space exploration. In the past years, most researchers try to solve this problem by concentrating on the choice of the upwind schemes or the definition of the cell Reynolds number. However, the cell Reynolds number dependencies and limiter dependencies of the upwind schemes, which are of great importance to their performances in hypersonic heating computations, are concerned by few people. In this paper, we conduct a systematic study on these properties respectively. Results in our test cases show that SLAU (Simple Low-dissipation AUSM-family) is with a much higher level of accuracy and robustness in hypersonic heating predictions. Also, it performs much better in terms of the limiter dependency and the cell Reynolds number dependency.

Radiation dominated acoustophoresis driven by surface acoustic waves.

Science.gov (United States)

Guo, Jinhong; Kang, Yuejun; Ai, Ye

2015-10-01

Acoustophoresis-based particle manipulation in microfluidics has gained increasing attention in recent years. Despite the fact that experimental studies have been extensively performed to demonstrate this technique for various microfluidic applications, numerical simulation of acoustophoresis driven by surface acoustic waves (SAWs) has still been largely unexplored. In this work, a numerical model taking into account the acoustic-piezoelectric interaction was developed to simulate the generation of a standing surface acoustic wave (SSAW) field and predict the acoustic pressure field in the liquid. Acoustic radiation dominated particle tracing was performed to simulate acoustophoresis of particles with different sizes undergoing a SSAW field. A microfluidic device composed of two interdigital transducers (IDTs) for SAW generation and a microfluidic channel was fabricated for experimental validation. Numerical simulations could well capture the focusing phenomenon of particles to the pressure nodes in the experimental observation. Further comparison of particle trajectories demonstrated considerably quantitative agreement between numerical simulations and experimental results with fitting in the applied voltage. Particle switching was also demonstrated using the fabricated device that could be further developed as an active particle sorting device. Copyright © 2015 Elsevier Inc. All rights reserved.

Ramjet Nozzle Analysis for Transport Aircraft Configuration for Sustained Hypersonic Flight

Directory of Open Access Journals (Sweden)

Raman Baidya

2018-04-01

Full Text Available For the past several decades, research dealing with hypersonic flight regimes has been restricted mainly to military applications. Hypersonic transportation could be a possible and affordable solution to travel in the medium term and there is renewed interest from several private organisations for commercial exploitation in this direction. Various combined cycle propulsion configurations have been proposed and the present paper deals with implications for the nozzle component of a ramjet configuration as part of one such combined cycle propulsion configuration. An investigation was undertaken for a method of turbine-based propulsion which enables the hypersonic vehicle to take off under its own power and propel the aircraft under different mission profiles into ramjet operational Mach regimes. The present study details an optimal method of ramjet exhaust expansion to produce sufficient thrust to propel the vehicle into altitudes and Mach regimes where scramjet operation can be initiated. This aspect includes a Computational Fluid Dynamics (CFD-based geometric study to determine the optimal configuration to provide the best thrust values. The CFD parametric analysis investigated three candidate nozzles and indicated that the dual bell nozzle design produced the highest thrust values when compared to other nozzle geometries. The altitude adaptation study also validated the effectiveness of the nozzle thrust at various altitudes without compromising its thrust-producing capabilities. Computational data were validated against published experimental data, which indicated that the computed values correlated well with the experimental data.

Dissociation–recombination models in hypersonic boundary layer O2/O flows

International Nuclear Information System (INIS)

Armenise, I.; Esposito, F.

2012-01-01

Graphical abstract: In hypersonic boundary layers, in which the temperature strongly decreases from the edge to the body surface, the coupling of transport phenomena and chemical kinetics causes a strong vibrational non-equilibrium, as demonstrated by the vibrational distributions and the pseudo-first-order dissociation constants. In this work a pure O2/O mixture has been investigated to evaluate the role of new multiquanta atom-molecule collision rate coefficients, calculated by means of a quasiclassical trajectory (QCT) method. Highlights: ► We evaluate the vibrational non-equilibrium in oxygen hypersonic boundary layer flows. ► We adopt a state-to-state vibrational kinetics model. ► We use updated quasicassical trajectory atom–molecule collision rate coefficients. ► Multiquanta transitions and direct dissociation–recombination are important. ► We calculate the heat flux through the boundary layer. - Abstract: A recent complete set of oxygen atom–molecule collision rate coefficients, calculated by means of a quasiclassical trajectory (QCT) method, has been used to evaluate the vibrational non-equilibrium in hypersonic boundary layer flows. The importance of multiquanta transitions has been demonstrated. Moreover a new ‘direct dissociation–recombination’ (DDR) model has been adopted and the corresponding results differ from the ones obtained with the ladder-climbing (LC) model, characterized by the extrapolation of bound-to-bound transitions to the continuum. The heat flux through the boundary layer and at the surface has been calculated too.

RTO WG 10: Test Cases for CFD Validation of Hypersonic Flight

National Research Council Canada - National Science Library

Knight, Doyle

2006-01-01

.... An overview of Subgroup 3 (SG 3) is presented in this paper. The SG 3 participants defined six topical areas for which validation of CFD methodologies was deemed essential for effective analysis and design of propelled hypersonic vehicles...

Technologies for propelled hypersonic flight: Technologies des vols hypersoniques propulsés

National Research Council Canada - National Science Library

2006-01-01

These reports document the results of the Applied Vehicle Technology Panel Working Group 10, Subgroups 1, 2, and 3, who aimed to address selected critical issues related to propelled hypersonic flight...

Observer-based linear parameter varying H∞ tracking control for hypersonic vehicles

Directory of Open Access Journals (Sweden)

Yiqing Huang

2016-11-01

Full Text Available This article aims to develop observer-based linear parameter varying output feedback H∞ tracking controller for hypersonic vehicles. Due to the complexity of an original nonlinear model of the hypersonic vehicle dynamics, a slow–fast loop linear parameter varying polytopic model is introduced for system stability analysis and controller design. Then, a state observer is developed by linear parameter varying technique in order to estimate the unmeasured attitude angular for slow loop system. Also, based on the designed linear parameter varying state observer, a kind of attitude tracking controller is presented to reduce tracking errors for all bounded reference attitude angular inputs. The closed-loop linear parameter varying system is proved to be quadratically stable by Lypapunov function technique. Finally, simulation results show that the developed linear parameter varying H∞ controller has good tracking capability for reference commands.

Supersonic Ionization Wave Driven by Radiation Transport in a Short-Pulse Laser-Produced Plasma

International Nuclear Information System (INIS)

Ditmire, T.; Gumbrell, E.T.; Smith, R.A.; Mountford, L.; Hutchinson, M.H.

1996-01-01

Through the use of an ultrashort (2ps) optical probe, we have time resolved the propagation of an ionization wave into solid fused silica. This ionization wave results when a plasma is created by the intense irradiation of a solid target with a 2ps laser pulse. We find that the velocity of the ionization wave is consistent with radiation driven thermal transport, exceeding the velocity expected from simple electron thermal conduction by nearly an order of magnitude. copyright 1996 The American Physical Society

Shock stand off Calculations for Hemisphere in Hypersonic Flows

International Nuclear Information System (INIS)

Hanif, M.; Ghaffar, A.; Bilal, S.; Zahir, S.; Khan, M.A.

2004-01-01

The shape and location of shock has been studied by solving the axi symmetric Navier Stokes Equations for a hemisphere in hypersonic flow. The effect of Mach number on shock stand-off distance has been investigated. It is found that the shock location varies with Mach number and the free stream conditions at a given nose radius. (author)

Miniaturized compact water-cooled pitot-pressure probe for flow-field surveys in hypersonic wind tunnels

Science.gov (United States)

Ashby, George C.

1988-01-01

An experimental investigation of the design of pitot probes for flowfield surveys in hypersonic wind tunnels is reported. The results show that a pitot-pressure probe can be miniaturized for minimum interference effects by locating the transducer in the probe support body and water-cooling it so that the pressure-settling time and transducer temperature are compatible with hypersonic tunnel operation and flow conditions. Flowfield surveys around a two-to-one elliptical cone model in a 20-inch Mach 6 wind tunnel using such a probe show that probe interference effects are essentially eliminated.

On nitrogen condensation in hypersonic nozzle flows: Numerical method and parametric study

KAUST Repository

Lin, Longyuan; Cheng, Wan; Luo, Xisheng; Qin, Fenghua

2013-01-01

A numerical method for calculating two-dimensional planar and axisymmetric hypersonic nozzle flows with nitrogen condensation is developed. The classical nucleation theory with an empirical correction function and the modified Gyarmathy model

Improved-Delayed-Detached-Eddy Simulation of cavity-induced transition in hypersonic boundary layer

International Nuclear Information System (INIS)

Xiao, Lianghua; Xiao, Zhixiang; Duan, Zhiwei; Fu, Song

2015-01-01

Highlights: • This work is about hypersonic cavity-induced transition with IDDES approach. • The length-to-width-to-depth ratio of the cavity is 19.9:3.57:1 at AoA −10° and −15°. • Flow remains laminar at −10°, transition occurs at −15° and cavity changed from open to close type. • Streamwise vortices, impingement shock, traveling shocks and exit shock are observed. • Breakdown of these vortices triggering rapid flow transition. - Abstract: Hypersonic flow transition from laminar to turbulent due to the surface irregularities, like local cavities, can greatly affect the surface heating and skin friction. In this work, the hypersonic flows over a three-dimensional rectangular cavity with length-to-width-to-depth ratio, L:W:D, of 19.9:3.57:1 at two angles of attack (AoA) were numerically studied with Improved-Delayed-Detached-Eddy Simulation (IDDES) method to highlight the mechanism of transition triggered by the cavity. The present approach was firstly applied to the transonic flow over M219 rectangular cavity. The results, including the fluctuating pressure and frequency, agreed with experiment well. In the hypersonic case at Mach number about 9.6 the cavity is seen as “open” at AoA of −10° but “closed” at AoA of −15° unconventional to the two-dimensional cavity case where the flow always exhibits closed cavity feature when the length-to-depth ratio L/D is larger than 14. For the open cavity flow, the shear layer is basically steady and the flow maintains laminar. For the closed cavity case, the external flow goes into the cavity and impinges on the bottom floor. High intensity streamwise vortices, impingement shock and exit shock are observed causing breakdown of these vortices triggering rapid flow transition

On nitrogen condensation in hypersonic nozzle flows: Numerical method and parametric study

KAUST Repository

Lin, Longyuan

2013-12-17

A numerical method for calculating two-dimensional planar and axisymmetric hypersonic nozzle flows with nitrogen condensation is developed. The classical nucleation theory with an empirical correction function and the modified Gyarmathy model are used to describe the nucleation rate and the droplet growth, respectively. The conservation of the liquid phase is described by a finite number of moments of the size distribution function. The moment equations are then combined with the Euler equations and are solved by the finite-volume method. The numerical method is first validated by comparing its prediction with experimental results from the literature. The effects of nitrogen condensation on hypersonic nozzle flows are then numerically examined. The parameters at the nozzle exit under the conditions of condensation and no-condensation are evaluated. For the condensation case, the static pressure, the static temperature, and the amount of condensed fluid at the nozzle exit decrease with the increase of the total temperature. Compared with the no-condensation case, both the static pressure and temperature at the nozzle exit increase, and the Mach number decreases due to the nitrogen condensation. It is also indicated that preheating the nitrogen gas is necessary to avoid the nitrogen condensation even for a hypersonic nozzle with a Mach number of 5 operating at room temperatures. © 2013 Springer-Verlag Berlin Heidelberg.

The Hypersonic Revolution. Case Studies in the History of Hypersonic Technology. Volume III: The Quest for the Orbital Jet: The National Aero-Space Plane Program (1983-1995)

National Research Council Canada - National Science Library

Schwelkart, Larry

1998-01-01

... that could fly fast enough to attain orbital velocity, is considered a success by many of the participants.1 They contend that by "showing up," NASP survived long enough to produce what many deem critical technologies for hypersonic flight...

Central dose data management and analysis in IT-driven radiation protection strategies

International Nuclear Information System (INIS)

Ward, M.; Hughes, D.; Connolly, P.; Moores, B. M.

2005-01-01

The applications of information technology in health care are now widespread and continue to grow. Medical imaging is at the forefront of this revolution and the introduction of digital detection methods to replace film is now addressing the diagnostic X-ray market, the most routinely employed imaging modality. The introduction of picture archiving and communication systems, hospital and radiology information systems is well underway, and the integration of radiation protection initiatives into these developments is desirable. In north-west UK, a project aimed at developing and implementing IT-driven radiation protection strategies has been underway for the past 10 y. Such strategies are geared towards the support of European Commission patient dose directive 97/43 EURATOM, in particular the need to implement clinical audit, patient dose audit and to establish dose reference levels. This paper demonstrates the national and local requirements for establishing a central dose data management system for use in radiation protection strategies. In particular, such a system can help develop and support the role of a medical physics expert in optimisation. The scientific requirements for such an approach are presented in this paper, and a prototype system is described. Preliminary results obtained with the central data management facility are also presented and the implication for analysing multiple site dose data in optimisation strategies for digital radiographic technology is highlighted. (authors)

Hypersonic Transition and Turbulence with Non-Equilibrium Thermochemistry

Science.gov (United States)

2009-08-31

from the literamre. In summary, this AFOSR MURI project has resulted in the production of new knowledge that should significantly improve the accuracy...behavior. The accumulated knowledge and understanding are expected to help development of better dissipation models for compressible flow fields. 2.23.2...8ffipüC<Pressurt Modieung suggestions from physics study <T acautttc Hypersonic Mach numbers Supersonic Mach numbers * skier * *a Subsonic

Hypersonic Inflatable Aerodynamic Decelerator (HIAD) Technology Development Overview

Science.gov (United States)

Hughes, Stephen J.; Cheatwood, F. McNeil; Calomino, Anthony M.; Wright, Henry S.; Wusk, Mary E.; Hughes, Monica F.

2013-01-01

The successful flight of the Inflatable Reentry Vehicle Experiment (IRVE)-3 has further demonstrated the potential value of Hypersonic Inflatable Aerodynamic Decelerator (HIAD) technology. This technology development effort is funded by NASA's Space Technology Mission Directorate (STMD) Game Changing Development Program (GCDP). This paper provides an overview of a multi-year HIAD technology development effort, detailing the projects completed to date and the additional testing planned for the future.

Multiple-step fault estimation for interval type-II T-S fuzzy system of hypersonic vehicle with time-varying elevator faults

Directory of Open Access Journals (Sweden)

Jin Wang

2017-03-01

Full Text Available This article proposes a multiple-step fault estimation algorithm for hypersonic flight vehicles that uses an interval type-II Takagi–Sugeno fuzzy model. An interval type-II Takagi–Sugeno fuzzy model is developed to approximate the nonlinear dynamic system and handle the parameter uncertainties of hypersonic firstly. Then, a multiple-step time-varying additive fault estimation algorithm is designed to estimate time-varying additive elevator fault of hypersonic flight vehicles. Finally, the simulation is conducted in both aspects of modeling and fault estimation; the validity and availability of such method are verified by a series of the comparison of numerical simulation results.

Adaptive fuzzy tracking control for a constrained flexible air-breathing hypersonic vehicle based on actuator compensation

Directory of Open Access Journals (Sweden)

Peng Fei Wang

2016-10-01

Full Text Available The design of an adaptive fuzzy tracking control for a flexible air-breathing hypersonic vehicle with actuator constraints is discussed. Based on functional decomposition methodology, velocity and altitude controllers are designed. Fuzzy logic systems are applied to approximate the lumped uncertainty of each subsystem of air-breathing hypersonic vehicle model. Every controllers contain only one adaptive parameter that needs to be updated online with a minimal-learning-parameter scheme. The back-stepping design is not demanded by converting the altitude subsystem into the normal output-feedback formulation, which predigests the design of a controller. The special contribution is that novel auxiliary systems are developed to compensate both the tracking errors and desired control laws, based on which the explored controller can still provide effective tracking of velocity and altitude commands when the inputs are saturated. Finally, reference trajectory tracking simulation shows the effectiveness of the proposed method in its application to air-breathing hypersonic vehicle control.

Machine learning based cloud mask algorithm driven by radiative transfer modeling

Science.gov (United States)

Chen, N.; Li, W.; Tanikawa, T.; Hori, M.; Shimada, R.; Stamnes, K. H.

2017-12-01

Cloud detection is a critically important first step required to derive many satellite data products. Traditional threshold based cloud mask algorithms require a complicated design process and fine tuning for each sensor, and have difficulty over snow/ice covered areas. With the advance of computational power and machine learning techniques, we have developed a new algorithm based on a neural network classifier driven by extensive radiative transfer modeling. Statistical validation results obtained by using collocated CALIOP and MODIS data show that its performance is consistent over different ecosystems and significantly better than the MODIS Cloud Mask (MOD35 C6) during the winter seasons over mid-latitude snow covered areas. Simulations using a reduced number of satellite channels also show satisfactory results, indicating its flexibility to be configured for different sensors.

Efficient adaptive constrained control with time-varying predefined performance for a hypersonic flight vehicle

Directory of Open Access Journals (Sweden)

Caisheng Wei

2017-03-01

Full Text Available A novel low-complexity adaptive control method, capable of guaranteeing the transient and steady-state tracking performance in the presence of unknown nonlinearities and actuator saturation, is investigated for the longitudinal dynamics of a generic hypersonic flight vehicle. In order to attenuate the negative effects of classical predefined performance function for unknown initial tracking errors, a modified predefined performance function with time-varying design parameters is presented. Under the newly developed predefined performance function, two novel adaptive controllers with low-complexity computation are proposed for velocity and altitude subsystems of the hypersonic flight vehicle, respectively. Wherein, different from neural network-based approximation, a least square support vector machine with only two design parameters is utilized to approximate the unknown hypersonic dynamics. And the relevant ideal weights are obtained by solving a linear system without resorting to specialized optimization algorithms. Based on the approximation by least square support vector machine, only two adaptive scalars are required to be updated online in the parameter projection method. Besides, a new finite-time-convergent differentiator, with a quite simple structure, is proposed to estimate the unknown generated state variables in the newly established normal output-feedback formulation of altitude subsystem. Moreover, it is also employed to obtain accurate estimations for the derivatives of virtual controllers in a recursive design. This avoids the inherent drawback of backstepping — “explosion of terms” and makes the proposed control method achievable for the hypersonic flight vehicle. Further, the compensation design is employed when the saturations of the actuator occur. Finally, the numerical simulations validate the efficiency of the proposed finite-time-convergent differentiator and control method.

Laser-driven particle acceleration towards radiobiology and medicine

CERN Document Server

2016-01-01

This book deals with the new method of laser-driven acceleration for application to radiation biophysics and medicine. It provides multidisciplinary contributions from world leading scientist in order to assess the state of the art of innovative tools for radiation biology research and medical applications of ionizing radiation. The book contains insightful contributions on highly topical aspects of spatio-temporal radiation biophysics, evolving over several orders of magnitude, typically from femtosecond and sub-micrometer scales. Particular attention is devoted to the emerging technology of laser-driven particle accelerators and their applicatio to spatio-temporal radiation biology and medical physics, customization of non-conventional and selective radiotherapy and optimized radioprotection protocols.

Nonlinear Constrained Adaptive Backstepping Tracking Control for a Hypersonic Vehicle with Uncertainty

Directory of Open Access Journals (Sweden)

Qin Zou

2015-01-01

Full Text Available The control problem of a flexible hypersonic vehicle is presented, where input saturation and aerodynamic uncertainty are considered. A control-oriented model including aerodynamic uncertainty is derived for simple controller design due to the nonlinearity and complexity of hypersonic vehicle model. Then it is separated into velocity subsystem and altitude subsystem. On the basis of the integration of robust adaptive control and backstepping technique, respective controller is designed for each subsystem, where an auxiliary signal provided by an additional dynamic system is used to compensate for the control saturation effect. Then to deal with the “explosion of terms” problem inherent in backstepping control, a novel first-order filter is proposed. Simulation results are included to demonstrate the effectiveness of the adaptive backstepping control scheme.

Parametric Study of Cantilever Plates Exposed to Supersonic and Hypersonic Flows

Science.gov (United States)

Sri Harsha, A.; Rizwan, M.; Kuldeep, S.; Giridhara Prasad, A.; Akhil, J.; Nagaraja, S. R.

2017-08-01

Analysis of hypersonic flows associated with re-entry vehicles has gained a lot of significance due to the advancements in Aerospace Engineering. An area that is studied extensively by researchers is the simultaneous reduction aerodynamic drag and aero heating in re-entry vehicles. Out of the many strategies being studied, the use of aerospikes at the stagnation point of the vehicle is found to give favourable results. The structural stability of the aerospike becomes important as it is exposed to very high pressures and temperatures. Keeping this in view, the deflection and vibration of an inclined cantilever plate in hypersonic flow is carried out using ANSYS. Steady state pressure distribution obtained from Fluent is applied as load to the transient structural module for analysis. After due validation of the methods, the effects of parameters like flow Mach number, plate inclination and plate thickness on the deflection and vibration are studied.

Concept of a tunable source of coherent THz radiation driven by a plasma modulated electron beam

Science.gov (United States)

Zhang, H.; Konoplev, I. V.; Doucas, G.; Smith, J.

2018-04-01

We have carried out numerical studies which consider the modulation of a picosecond long relativistic electron beam in a plasma channel and the generation of a micro-bunched train. The subsequent propagation of the micro-bunched beam in the vacuum area was also investigated. The same numerical model was then used to simulate the radiation arising from the interaction of the micro-bunched beam with a metallic grating. The dependence of the radiation spectrum on the parameters of the micro-bunched beam has been studied and the tunability of the radiation by the variation of the micro-bunch spacing has been demonstrated. The micro-bunch spacing can be changed easily by altering the plasma density without changing the beam energy or current. Using the results of these studies, we develop a conceptual design of a tunable source of coherent terahertz (THz) radiation driven by a plasma modulated beam. Such a source would be a potential and useful alternative to conventional vacuum THz tubes and THz free-electron laser sources.

Application of supersonic linear theory and hypersonic impact methods to three nonslender hypersonic airplane concepts at Mach numbers from 1.10 to 2.86

Science.gov (United States)

Pittman, J. L.

1979-01-01

Aerodynamic predictions from supersonic linear theory and hypersonic impact theory were compared with experimental data for three hypersonic research airplane concepts over a Mach number range from 1.10 to 2.86. The linear theory gave good lift prediction and fair to good pitching-moment prediction over the Mach number (M) range. The tangent-cone theory predictions were good for lift and fair to good for pitching moment for M more than or equal to 2.0. The combined tangent-cone theory predictions were good for lift and fair to good for pitching moment for M more than or equal to 2.0. The combined tangent-cone/tangent-wedge method gave the least accurate prediction of lift and pitching moment. The zero-lift drag was overestimated, especially for M less than 2.0. The linear theory drag prediction was generally poor, with areas of good agreement only for M less than or equal to 1.2. For M more than or equal to 2.), the tangent-cone method predicted the zero-lift drag most accurately.

Computational Tool for Coupled Simulation of Nonequilibrium Hypersonic Flows with Ablation, Phase II

Data.gov (United States)

National Aeronautics and Space Administration — The goal of this SBIR project is to develop a predictive computational tool for the aerothermal environment around ablation-cooled hypersonic atmospheric entry...

Terahertz Quantum Cascade Laser-Based Sensors for Hypersonic Flows (7274-050), Phase I

Data.gov (United States)

National Aeronautics and Space Administration — Ground test facilities are used by NASA to simulate the conditions present during flight at hypersonic velocities, to test thermal protection materials for existing...

Biofouling Removal and Protein Detection Using a Hypersonic Resonator.

Science.gov (United States)

Pan, Shuting; Zhang, Hongxiang; Liu, Wenpeng; Wang, Yanyan; Pang, Wei; Duan, Xuexin

2017-08-25

Nonspecific binding (NSB) is a general issue for surface based biosensors. Various approaches have been developed to prevent or remove the NSBs. However, these approaches either increased the background signals of the sensors or limited to specific transducers interface. In this work, we developed a hydrodynamic approach to selectively remove the NSBs using a microfabricated hypersonic resonator with 2.5 gigahertz (GHz) resonant frequency. The high frequency device facilitates generation of multiple controlled microvortexes which then create cleaning forces at the solid-liquid interfaces. The competitive adhesive and cleaning forces have been investigated using the finite element method (FEM) simulation, identifying the feasibility of the vortex-induced NSB removal. NSB proteins have been selectively removed experimentally both on the surface of the resonator and on other substrates which contact the vortexes. Thus, the developed hydrodynamic approach is believed to be a simple and versatile tool for NSB removal and compatible to many sensor systems. The unique feature of the hypersonic resonator is that it can be used as a gravimetric sensor as well; thus a combined NSB removal and protein detection dual functional biosensor system is developed.

Impulse Force Balance for Ultrashort Duration Hypersonic Test Facilities

Directory of Open Access Journals (Sweden)

P. Singh

2015-01-01

Full Text Available This paper presents the measurement of side force, pitching, and yawing moments on a model, using an accelerometer force balance, in a short duration hypersonic shock tunnel. The test model is a blunt-nosed, flapped delta wing, mounted on a support sting through a force balance. The flexible rubber bushes constituting the balance allow the model to float freely on the sting during the test. The accelerometers were located in the model to record accelerations in the directions of interest. The model was tested in shock tunnel at Mach 8 at different angles of incidence with the freestream. Dynamic calibration of the test assembly was carried out for the acquisition of impulse response functions for the above components of force and moments, using an impulse hammer. The convolution technique was applied to derive the impulse response functions. The accelerometer outputs from the model in the hypersonic freestream were processed using the respective impulse response functions to derive the unknown aerodynamic force and moments. The newly adopted convolution technique has been found very effective for data reduction from accelerometer force balances developed for shock tunnel applications.

Direct Numerical Simulation of Acoustic Noise Generation from the Nozzle Wall of a Hypersonic Wind Tunnel

Science.gov (United States)

Huang, Junji; Duan, Lian; Choudhari, Meelan; Missouri Univ of Sci; Tech Team; NASA Langley Research Center Team

2017-11-01

Direct numerical simulations (DNS) are used to examine the acoustic noise generation from the turbulent boundary layer on the nozzle wall of a Mach 6 Ludwieg Tube. The emphasis is on characterizing the freestream acoustic pressure disturbances radiated from the nozzle-wall turbulent boundary layer and comparing it with acoustic noise generated from a single, flat wall in an unconfined setting at a similar freestream Mach number to assess the effects of noise reverberation. In particular, the numerical database is used to provide insights into the pressure disturbance spectrum and amplitude scaling with respect to the boundary-layer parameters as well as to understand the acoustic source mechanisms. Such information is important for characterizing the freestream disturbance environment in conventional (i.e., noisy) hypersonic wind tunnels. Air Force Office of Scientific Research Award No. FA9550-14-1-0170.

Mode Transition Variable Geometry for High Speed Inlets for Hypersonic Aircraft, Phase I

Data.gov (United States)

National Aeronautics and Space Administration — Hypersonic propulsion research has been a focus of the NASA aeronautics program for years. Previous high-speed cruise and space access programs have examined the...

An Upgrade of the Imaging for Hypersonic Experimental Aeroheating Testing (IHEAT) Software

Science.gov (United States)

Mason, Michelle L.; Rufer, Shann J.

2015-01-01

The Imaging for Hypersonic Experimental Aeroheating Testing (IHEAT) code is used at NASA Langley Research Center to analyze global aeroheating data on wind tunnel models tested in the Langley Aerothermodynamics Laboratory. One-dimensional, semi-infinite heating data derived from IHEAT are used to design thermal protection systems to mitigate the risks due to the aeroheating loads on hypersonic vehicles, such as re-entry vehicles during descent and landing procedures. This code was originally written in the PV-WAVE programming language to analyze phosphor thermography data from the two-color, relativeintensity system developed at Langley. To increase the efficiency, functionality, and reliability of IHEAT, the code was migrated to MATLAB syntax and compiled as a stand-alone executable file labeled version 4.0. New features of IHEAT 4.0 include the options to batch process all of the data from a wind tunnel run, to map the two-dimensional heating distribution to a three-dimensional computer-aided design model of the vehicle to be viewed in Tecplot, and to extract data from a segmented line that follows an interesting feature in the data. Results from IHEAT 4.0 were compared on a pixel level to the output images from the legacy code to validate the program. The differences between the two codes were on the order of 10-5 to 10-7. IHEAT 4.0 replaces the PV-WAVE version as the production code for aeroheating experiments conducted in the hypersonic facilities at NASA Langley.

The Role of Guidance, Navigation, and Control in Hypersonic Vehicle Multidisciplinary Design and Optimization

Science.gov (United States)

Ouzts, Peter J.; Soloway, Donald I.; Moerder, Daniel D.; Wolpert, David H.; Benavides, Jose Victor

2009-01-01

Airbreathing hypersonic systems offer distinct performance advantages over rocket-based systems for space access vehicles. However, these performance advantages are dependent upon advances in current state-of-the-art technologies in many areas such as ram/scramjet propulsion integration, high temperature materials, aero-elastic structures, thermal protection systems, transition to hypersonics and hypersonic control elements within the framework of complex physics and new design methods. The complex interactions between elements of an airbreathing hypersonic vehicle represent a new paradigm in vehicle design to achieve the optimal performance necessary to meet space access mission objectives. In the past, guidance, navigation, and control (GNC) analysis often follows completion of the vehicle conceptual design process. Individual component groups design subsystems which are then integrated into a vehicle configuration. GNC is presented the task of developing control approaches to meet vehicle performance objectives given that configuration. This approach may be sufficient for vehicles where significant performance margins exist. However, for higher performance vehicles engaging the GNC discipline too late in the design cycle has been costly. For example, the X-29 experimental flight vehicle was built as a technology demonstrator. One of the many technologies to be demonstrated was the use of light-weight material composites for structural components. The use of light-weight materials increased the flexibility of the X- 29 beyond that of conventional metal alloy constructed aircraft. This effect was not considered when the vehicle control system was designed and built. The impact of this is that the control system did not have enough control authority to compensate for the effects of the first fundamental structural mode of the vehicle. As a result, the resulting pitch rate response of the vehicle was below specification and no post-design changes could recover the

Near Space Hypersonic Unmanned Aerial Vehicle Dynamic Surface Backstepping Control Design

Directory of Open Access Journals (Sweden)

Jinyong YU

2014-07-01

Full Text Available Compared with traditional aircraft, the near space hypersonic unmanned aerial vehicle control system design must deal with the extra prominent dynamics characters, which are differ from the traditional aircrafts control system design. A new robust adaptive control design method is proposed for one hypersonic unmanned aerial vehicle (HSUAV uncertain MIMO nonaffine block control system by using multilayer neural networks, feedback linearization technology, and dynamic surface backstepping. Multilayer neural networks are used to compensate the influence from the uncertain, which designs the robust terms to solve the problem from approach error. Adaptive backstepping is adopted designed to ensure control law, the dynamic surface control strategy to eliminate “the explosion of terms” by introducing a series of first order filters to obtain the differentiation of the virtual control inputs. Finally, nonlinear six-degree-of-freedom (6-DOF numerical simulation results for a HSUAV model are presented to demonstrate the effectiveness of the proposed method.

Modeling of the plasma generated in a rarefied hypersonic shock layer

International Nuclear Information System (INIS)

Farbar, Erin D.; Boyd, Iain D.

2010-01-01

In this study, a rigorous numerical model is developed to simulate the plasma generated in a rarefied, hypersonic shock layer. The model uses the direct simulation Monte Carlo (DSMC) method to treat the particle collisions and the particle-in-cell (PIC) method to simulate the plasma dynamics in a self-consistent manner. The model is applied to compute the flow along the stagnation streamline in front of a blunt body reentering the Earth's atmosphere at very high velocity. Results from the rigorous DSMC-PIC model are compared directly to the standard DSMC modeling approach that uses the ambipolar diffusion approximation to simulate the plasma dynamics. It is demonstrated that the self-consistent computation of the plasma dynamics using the rigorous DSMC-PIC model captures many physical phenomena not accurately predicted by the standard modeling approach. These computations represent the first assessment of the validity of the ambipolar diffusion approximation when predicting the rarefied plasma generated in a hypersonic shock layer.

Cavity-type hypersonic phononic crystals

International Nuclear Information System (INIS)

Sato, A; Fytas, G; Pennec, Y; Djafari-Rouhani, B; Yanagishita, T; Masuda, H; Knoll, W

2012-01-01

We report on the engineering of the phonon dispersion diagram in monodomain anodic porous alumina (APA) films through the porosity and physical state of the material residing in the nanopores. Lattice symmetry and inclusion materials are theoretically identified to be the main factors which control the hypersonic acoustic wave propagation. This involves the interaction between the longitudinal and the transverse modes in the effective medium and a flat band characteristic of the material residing in the cavities. Air and filled nanopores, therefore, display markedly different dispersion relations and the inclusion materials lead to a locally resonant structural behavior uniquely determining their properties under confinement. APA films emerge as a new platform to investigate the rich acoustic phenomena of structured composite matter. (paper)

Critique of atomic physics instability mechanisms: Ionization-driven and radiative microinstabilities in the tokamak edge plasma

International Nuclear Information System (INIS)

Ross, D.W.

1994-01-01

The theory of atomic-process driven microinstabilities in the tokamak edge plasma is reexamined. It is found that these instabilities, as they are usually presented, do not exist. This assertion applies both to ionization-driven modes and to radiative condensation, or thermal-driven modes. The problem is that there exists no separation of time scales between the approach to equilibrium and the growth rate of the purported instabilities. Therefore, to describe the perturbation of an inhomogeneous plasma, it is essential either to establish an equilibrium that includes both perpendicular transport and the proposed source, or, alternatively, to follow the background evolution simultaneously with the growth of the modes. Neither has been done in theoretical or numerical studies of microinstabilities driven by atomic effects in tokamaks. Very near the density limit, macroscopic modes may be unstable, leading to marfes or disruptions, but perturbations of the equilibrium transport fluxes, when taken into account, are sufficient to stabilize the microscopic modes. If the equilibrium fluxes are not included a priori, the ordering breakdown persists into the nonlinear regime. Since the atomic driving terms are the same as in the linear limit, radial decorrelation lengths would have to approach background scale lengths to yield transport of significant magnitude. Under ordinary tokamak conditions, therefore, atomic processes are unlikely to provide an important driving mechanism for the microturbulence that is presumed to cause anomalous transport

DSMC simulation and experimental validation of shock interaction in hypersonic low density flow.

Science.gov (United States)

Xiao, Hong; Shang, Yuhe; Wu, Di

2014-01-01

Direct simulation Monte Carlo (DSMC) of shock interaction in hypersonic low density flow is developed. Three collision molecular models, including hard sphere (HS), variable hard sphere (VHS), and variable soft sphere (VSS), are employed in the DSMC study. The simulations of double-cone and Edney's type IV hypersonic shock interactions in low density flow are performed. Comparisons between DSMC and experimental data are conducted. Investigation of the double-cone hypersonic flow shows that three collision molecular models can predict the trend of pressure coefficient and the Stanton number. HS model shows the best agreement between DSMC simulation and experiment among three collision molecular models. Also, it shows that the agreement between DSMC and experiment is generally good for HS and VHS models in Edney's type IV shock interaction. However, it fails in the VSS model. Both double-cone and Edney's type IV shock interaction simulations show that the DSMC errors depend on the Knudsen number and the models employed for intermolecular interaction. With the increase in the Knudsen number, the DSMC error is decreased. The error is the smallest in HS compared with those in the VHS and VSS models. When the Knudsen number is in the level of 10(-4), the DSMC errors, for pressure coefficient, the Stanton number, and the scale of interaction region, are controlled within 10%.

RDHWT/MARIAH II Hypersonic Wind Tunnel Research Program

Science.gov (United States)

2008-09-01

Summary of Baseline Design Concepts SSTO : Single Stage to Orbit TSTO: Two Stage to Orbit RBCC: Rocket-Based Combined Cycle ODWE: Oblique Detonation...for most other hypersonic air-breathing propulsion applications. Required test times for the Mach 8 Cruise and SSTO type vehicles are shown in Table 3...Air-BreathingMach Range Length, m (ft) Propulsion Mach 8 Cruise Missile 4 to 8 4.3 (14) Hydrocarbon Scramjet SSTO Space Access with RBCC 0 to 14 62.8

Direct Numerical Simulation and Experimental Validation of Hypersonic Boundary-Layer Receptivity and Instability

National Research Council Canada - National Science Library

Zhong, Xiaolin

2007-01-01

.... During the three-year period, we have conducted extensive DNS studies on the receptivity of hypersonic boundary layer flows over a sharp wedge, a flat plate, a blunt cone, and the FRESH aeroshell...

Material Characterization for Hypersonic Vehicles by the Fast Mutipole Boundary Element Method, Phase I

Data.gov (United States)

National Aeronautics and Space Administration — Hypersonic aircraft are subjected to extreme conditions with respect to mechanical thermal and acoustic loads. Materials with complex microstructure, such as...

Design of a distributed radiator target for inertial fusion driven from two sides with heavy ion beams

International Nuclear Information System (INIS)

Tabak, M.; Callahan-Miller, D.

1997-01-01

We describe the status of a distributed radiator heavy ion target design. In integrated calculations this target ignited and produced 390-430 MJ of yieldwhen driven with 5.8-6.5 MJ of 3-4 GeV Pb ions. The target has cylindrical symmetry with disk endplates. The ions uniformly illuminate these endplates in a 5mm radius spot. We discuss the considerations which led to this design together with some previously unused design features: low density hohlraum walls in approximate pressure balance with internal low-Z fill materials, radiationsymmetry determined by the position of the radiator materials and particle ranges, and early time pressure symmetry possibly influenced by radiation shims. We discuss how this target scales to lower input energy or to lower beam power. Variant designs with more realistic beam focusing strategies are also discussed. We show the tradeoffs required for targets which accept higher particle energies

Hypersonic Poration of Membranes : From Triggered Release and Encapsulation to Drug Delivery

NARCIS (Netherlands)

Lu, Yao

2018-01-01

In this thesis, hypersonic poration is introduced as a new physical method to precisely control membrane permeability for the applications of controlled release and encapsulation, and enhanced drug delivery. Bulk acoustic wave (BAW) resonators of gigahertz (GHz) frequency have been fabricated using

PIC Simulations of Hypersonic Plasma Instabilities

Science.gov (United States)

Niehoff, D.; Ashour-Abdalla, M.; Niemann, C.; Decyk, V.; Schriver, D.; Clark, E.

2013-12-01

The plasma sheaths formed around hypersonic aircraft (Mach number, M > 10) are relatively unexplored and of interest today to both further the development of new technologies and solve long-standing engineering problems. Both laboratory experiments and analytical/numerical modeling are required to advance the understanding of these systems; it is advantageous to perform these tasks in tandem. There has already been some work done to study these plasmas by experiments that create a rapidly expanding plasma through ablation of a target with a laser. In combination with a preformed magnetic field, this configuration leads to a magnetic "bubble" formed behind the front as particles travel at about Mach 30 away from the target. Furthermore, the experiment was able to show the generation of fast electrons which could be due to instabilities on electron scales. To explore this, future experiments will have more accurate diagnostics capable of observing time- and length-scales below typical ion scales, but simulations are a useful tool to explore these plasma conditions theoretically. Particle in Cell (PIC) simulations are necessary when phenomena are expected to be observed at these scales, and also have the advantage of being fully kinetic with no fluid approximations. However, if the scales of the problem are not significantly below the ion scales, then the initialization of the PIC simulation must be very carefully engineered to avoid unnecessary computation and to select the minimum window where structures of interest can be studied. One method of doing this is to seed the simulation with either experiment or ion-scale simulation results. Previous experiments suggest that a useful configuration for studying hypersonic plasma configurations is a ring of particles rapidly expanding transverse to an external magnetic field, which has been simulated on the ion scale with an ion-hybrid code. This suggests that the PIC simulation should have an equivalent configuration

Hypersonic wave drag reduction performance of cylinders with repetitive laser energy depositions

International Nuclear Information System (INIS)

Fang, J; Hong, Y J; Li, Q; Huang, H

2011-01-01

It has been widely research that wave drag reduction on hypersonic vehicle by laser energy depositions. Using laser energy to reduce wave drag can improve vehicle performance. A second order accurate scheme based on finite-difference method and domain decomposition of structural grid is used to compute the drag performance of cylinders in a hypersonic flow of Mach number 2 at altitude of 15km with repetitive energy depositions. The effects of frequency on drag reduction are studied. The calculated results show: the recirculation zone is generated due to the interaction between bow shock over the cylinder and blast wave produced by energy deposition, and a virtual spike which is supported by an axis-symmetric recirculation, is formed in front of the cylinder. By increasing the repetitive frequency, the drag is reduced and the oscillation of the drag is decreased; however, the energy efficiency decreases by increasing the frequency.

THz and Sub-THz Capabilities of a Table-Top Radiation Source Driven by an RF Thermionic Electron Gun

Energy Technology Data Exchange (ETDEWEB)

Smirnov, Alexei V.; Agustsson, R.; Boucher, S.; Campese, Tara; Chen, Y.C.; Hartzell, Josiah J.; Jocobson, B.T.; Murokh, A.; O' Shea, F.H.; Spranza, E.; Berg, W.; Borland, M.; Dooling, J. C.; Erwin, L.; Lindberg, R. R.; Pasky, S.J.; Sereno, N.; Sun, Y.; Zholents, A.

2017-06-01

Design features and experimental results are presented for a sub-mm wave source [1] based on APS RF thermionic electron gun. The setup includes compact alpha-magnet, quadrupoles, sub-mm-wave radiators, and THz optics. The sub-THz radiator is a planar, oversized structure with gratings. Source upgrade for generation frequencies above 1 THz is discussed. The THz radiator will use a short-period undulator having 1 T field amplitude, ~20 cm length, and integrated with a low-loss oversized waveguide. Both radiators are integrated with a miniature horn antenna and a small ~90°-degree in-vacuum bending magnet. The electron beamline is designed to operate different modes including conversion to a flat beam interacting efficiently with the radiator. The source can be used for cancer diagnostics, surface defectoscopy, and non-destructive testing. Sub-THz experiment demonstrated a good potential of a robust, table-top system for generation of a narrow bandwidth THz radiation. This setup can be considered as a prototype of a compact, laser-free, flexible source capable of generation of long trains of Sub-THz and THz pulses with repetition rates not available with laser-driven sources.

Features of the Upgraded Imaging for Hypersonic Experimental Aeroheating Testing (IHEAT) Software

Science.gov (United States)

Mason, Michelle L.; Rufer, Shann J.

2016-01-01

The Imaging for Hypersonic Experimental Aeroheating Testing (IHEAT) software is used at the NASA Langley Research Center to analyze global aeroheating data on wind tunnel models tested in the Langley Aerothermodynamics Laboratory. One-dimensional, semi-infinite heating data derived from IHEAT are used in the design of thermal protection systems for hypersonic vehicles that are exposed to severe aeroheating loads, such as reentry vehicles during descent and landing procedures. This software program originally was written in the PV-WAVE(Registered Trademark) programming language to analyze phosphor thermography data from the two-color, relative-intensity system developed at Langley. To increase the efficiency, functionality, and reliability of IHEAT, the program was migrated to MATLAB(Registered Trademark) syntax and compiled as a stand-alone executable file labeled version 4.0. New features of IHEAT 4.0 include the options to perform diagnostic checks of the accuracy of the acquired data during a wind tunnel test, to extract data along a specified multi-segment line following a feature such as a leading edge or a streamline, and to batch process all of the temporal frame data from a wind tunnel run. Results from IHEAT 4.0 were compared on a pixel level to the output images from the legacy software to validate the program. The absolute differences between the heat transfer data output from the two programs were on the order of 10(exp -5) to 10(exp -7). IHEAT 4.0 replaces the PV-WAVE(Registered Trademark) version as the production software for aeroheating experiments conducted in the hypersonic facilities at NASA Langley.

A Numerical Study of 2-D Surface Roughness Effects on the Growth of Wave Modes in Hypersonic Boundary Layers

Science.gov (United States)

Fong, Kahei Danny

The current understanding and research efforts on surface roughness effects in hypersonic boundary-layer flows focus, almost exclusively, on how roughness elements trip a hypersonic boundary layer to turbulence. However, there were a few reports in the literature suggesting that roughness elements in hypersonic boundary-layer flows could sometimes suppress the transition process and delay the formation of turbulent flow. These reports were not common and had not attracted much attention from the research community. Furthermore, the mechanisms of how the delay and stabilization happened were unknown. A recent study by Duan et al. showed that when 2-D roughness elements were placed downstream of the so-called synchronization point, the unstable second-mode wave in a hypersonic boundary layer was damped. Since the second-mode wave is typically the most dangerous and dominant unstable mode in a hypersonic boundary layer for sharp geometries at a zero angle of attack, this result has pointed to an explanation on how roughness elements delay transition in a hypersonic boundary layer. Such an understanding can potentially have significant practical applications for the development of passive flow control techniques to suppress hypersonic boundary-layer transition, for the purpose of aero-heating reduction. Nevertheless, the previous study was preliminary because only one particular flow condition with one fixed roughness parameter was considered. The study also lacked an examination on the mechanism of the damping effect of the second mode by roughness. Hence, the objective of the current research is to conduct an extensive investigation of the effects of 2-D roughness elements on the growth of instability waves in a hypersonic boundary layer. The goal is to provide a full physical picture of how and when 2-D roughness elements stabilize a hypersonic boundary layer. Rigorous parametric studies using numerical simulation, linear stability theory (LST), and parabolized

The Integrated Computational Environment for Airbreathing Hypersonic Flight Vehicle Modeling and Design Evaluation, Phase I

Data.gov (United States)

National Aeronautics and Space Administration — An integrated computational environment for multidisciplinary, physics-based simulation and analyses of airbreathing hypersonic flight vehicles will be developed....

Hypersonic MHD Propulsion System Integration for the Mercury Lightcraft

International Nuclear Information System (INIS)

Myrabo, L.N.; Rosa, R.J.

2004-01-01

Introduced herein are the design, systems integration, and performance analysis of an exotic magnetohydrodynamic (MHD) slipstream accelerator engine for a single-occupant 'Mercury' lightcraft. This ultra-energetic, laser-boosted vehicle is designed to ride a 'tractor beam' into space, transmitted from a future orbital network of satellite solar power stations. The lightcraft's airbreathing combined-cycle engine employs a rotary pulsed detonation thruster mode for lift-off and landing, and an MHD slipstream accelerator mode at hypersonic speeds. The latter engine transforms the transatmospheric acceleration path into a virtual electromagnetic 'mass-driver' channel; the hypersonic momentum exchange process (with the atmosphere) enables engine specific impulses in the range of 6000 to 16,000 seconds, and propellant mass fractions as low as 10%. The single-stage-to-orbit, highly reusable lightcraft can accelerate at 3 Gs into low Earth orbit with its throttle just barely beyond 'idle' power, or virtually 'disappear' at 30 G's and beyond. The objective of this advanced lightcraft design is to lay the technological foundations for a safe, very low cost (e.g., 1000X below chemical rockets) air and space transportation for human life in the mid-21st Century - a system that will be completely 'green' and independent of Earth's limited fossil fuel reserves

Hypersonic MHD Propulsion System Integration for the Mercury Lightcraft

Science.gov (United States)

Myrabo, L. N.; Rosa, R. J.

2004-03-01

Introduced herein are the design, systems integration, and performance analysis of an exotic magnetohydrodynamic (MHD) slipstream accelerator engine for a single-occupant ``Mercury'' lightcraft. This ultra-energetic, laser-boosted vehicle is designed to ride a `tractor beam' into space, transmitted from a future orbital network of satellite solar power stations. The lightcraft's airbreathing combined-cycle engine employs a rotary pulsed detonation thruster mode for lift-off & landing, and an MHD slipstream accelerator mode at hypersonic speeds. The latter engine transforms the transatmospheric acceleration path into a virtual electromagnetic `mass-driver' channel; the hypersonic momentum exchange process (with the atmosphere) enables engine specific impulses in the range of 6000 to 16,000 seconds, and propellant mass fractions as low as 10%. The single-stage-to-orbit, highly reusable lightcraft can accelerate at 3 Gs into low Earth orbit with its throttle just barely beyond `idle' power, or virtually `disappear' at 30 G's and beyond. The objective of this advanced lightcraft design is to lay the technological foundations for a safe, very low cost (e.g., 1000X below chemical rockets) air and space transportation for human life in the mid-21st Century - a system that will be completely `green' and independent of Earth's limited fossil fuel reserves.

Recombination Catalysts for Hypersonic Fuels

Science.gov (United States)

Chinitz, W.

1998-01-01

The goal of commercially-viable access to space will require technologies that reduce propulsion system weight and complexity, while extracting maximum energy from the products of combustion. This work is directed toward developing effective nozzle recombination catalysts for the supersonic and hypersonic aeropropulsion engines used to provide such access to space. Effective nozzle recombination will significantly reduce rk=le length (hence, propulsion system weight) and reduce fuel requirements, further decreasing the vehicle's gross lift-off weight. Two such catalysts have been identified in this work, barium and antimony compounds, by developing chemical kinetic reaction mechanisms for these materials and determining the engine performance enhancement for a typical flight trajectory. Significant performance improvements are indicated, using only 2% (mole or mass) of these compounds in the combustor product gas.

Momentum-driven Winds from Radiatively Efficient Black Hole Accretion and Their Impact on Galaxies

Science.gov (United States)

Brennan, Ryan; Choi, Ena; Somerville, Rachel S.; Hirschmann, Michaela; Naab, Thorsten; Ostriker, Jeremiah P.

2018-06-01

We explore the effect of momentum-driven winds representing radiation-pressure-driven outflows from accretion onto supermassive black holes in a set of numerical hydrodynamical simulations. We explore two matched sets of cosmological zoom-in runs of 24 halos with masses ∼1012.0–1013.4 M ⊙ run with two different feedback models. Our “NoAGN” model includes stellar feedback via UV heating, stellar winds and supernovae, photoelectric heating, and cosmic X-ray background heating from a metagalactic background. Our fiducial “MrAGN” model is identical except that it also includes a model for black hole seeding and accretion, as well as heating and momentum injection associated with the radiation from black hole accretion. Our MrAGN model launches galactic outflows, which result in both “ejective” feedback—the outflows themselves that drive gas out of galaxies—and “preventative” feedback, which suppresses the inflow of new and recycling gas. As much as 80% of outflowing galactic gas can be expelled, and accretion can be suppressed by as much as a factor of 30 in the MrAGN runs when compared with the NoAGN runs. The histories of NoAGN galaxies are recycling dominated, with ∼70% of material that leaves the galaxy eventually returning, and the majority of outflowing gas reaccretes on 1 Gyr timescales without AGN feedback. Outflowing gas in the MrAGN runs has a higher characteristic velocity (500–1000 km s‑1 versus 100–300 km s‑1 for outflowing NoAGN gas) and travels as far as a few megaparsecs. Only ∼10% of ejected material is reaccreted in the MrAGN galaxies.

Algorithm For Hypersonic Flow In Chemical Equilibrium

Science.gov (United States)

Palmer, Grant

1989-01-01

Implicit, finite-difference, shock-capturing algorithm calculates inviscid, hypersonic flows in chemical equilibrium. Implicit formulation chosen because overcomes limitation on mathematical stability encountered in explicit formulations. For dynamical portion of problem, Euler equations written in conservation-law form in Cartesian coordinate system for two-dimensional or axisymmetric flow. For chemical portion of problem, equilibrium state of gas at each point in computational grid determined by minimizing local Gibbs free energy, subject to local conservation of molecules, atoms, ions, and total enthalpy. Major advantage: resulting algorithm naturally stable and captures strong shocks without help of artificial-dissipation terms to damp out spurious numerical oscillations.

Lightweight Ultrahigh Temperature CMC-Encased C/C Structure for Reentry and Hypersonic Applications, Phase II

Data.gov (United States)

National Aeronautics and Space Administration — Future reentry and hypersonic vehicles require advanced lightweight leading edge thermal protection systems that can provide the dual functionality of...

Airbreathing Hypersonic Systems Focus at NASA Langley Research Center

Science.gov (United States)

Hunt, James L.; Rausch, Vincent L.

1998-01-01

This paper presents the status of the airbreathing hypersonic airplane and space-access vehicle design matrix, reflects on the synergies and issues, and indicates the thrust of the effort to resolve the design matrix and to focus/advance systems technology maturation. Priority is given to the design of the vision operational vehicles followed by flow-down requirements to flight demonstrator vehicles and their design for eventual consideration in the Future-X Program.

Tracking performance and global stability guaranteed neural control of uncertain hypersonic flight vehicle

Directory of Open Access Journals (Sweden)

Tao Teng

2016-02-01

Full Text Available In this article, a global adaptive neural dynamic surface control with predefined tracking performance is developed for a class of hypersonic flight vehicles, whose accurate dynamics is hard to obtain. The control scheme developed in this paper overcomes the limitations of neural approximation region by employing a switching mechanism which incorporates an additional robust controller outside the neural approximation region to pull the transient state variables back when they overstep the neural approximation region, such that globally uniformly ultimately bounded stability can be guaranteed. Especially, the developed global adaptive neural control also improves the tracking performance by introducing an error transformation mechanism, such that both transient and steady-state performance can be shaped according to the predefined bounds. Simulation studies on the hypersonic flight vehicle validate that the designed controller has good velocity modulation and velocity stability performance.

Further analysis of MHD acceleration for a hypersonic wind tunnel

International Nuclear Information System (INIS)

Christiansen, M.J.; Schmidt, H.J.; Chapman, J.N.

1995-01-01

A previously completed MHD study of the use of an MHD accelerator with seeded air from a state-of-the-art arc heater, was generally hailed as showing that the system studied has some promise of meeting the most critical hypersonic testing requirements. However, some concerns existed about certain aspects of the results. This paper discusses some of these problems and presents analysis of potential solutions. Specifically the problems addressed are; reducing the amount of seed in the flow, reducing test chamber temperatures, and reducing the oxygen dissociation. Modeling techniques are used to study three design variables of the MHD accelerator. The accelerator channel inlet Mach number, the accelerator channel divergence angle, and the magnetic field strength are all studied. These variables are all optimized to meet the goals for seed, temperature, and dissociated oxygen reduction. The results of this paper are encouraging, showing that all three goals can be met. General relationships are observed as to how the design variables affect the performance of the MHD accelerator facility. This paper expands on the results presented in the UTSI report and further supports the feasibility of MHD acceleration as a means to provide hypersonic flight simulation

Effects of shock on hypersonic boundary layer stability

Science.gov (United States)

Pinna, F.; Rambaud, P.

2013-06-01

The design of hypersonic vehicles requires the estimate of the laminar to turbulent transition location for an accurate sizing of the thermal protection system. Linear stability theory is a fast scientific way to study the problem. Recent improvements in computational capabilities allow computing the flow around a full vehicle instead of using only simplified boundary layer equations. In this paper, the effect of the shock is studied on a mean flow provided by steady Computational Fluid Dynamics (CFD) computations and simplified boundary layer calculations.

Modeling study of rarefied gas effects on hypersonic reacting stagnation flows

Science.gov (United States)

Wang, Zhihui; Bao, Lin

2014-12-01

Recent development of the near space hypersonic sharp leading vehicles has raised a necessity to fast and accurately predict the aeroheating in hypersonic rarefied flows, which challenges our understanding of the aerothermodynamics and aerothermochemistry. The present flow and heat transfer problem involves complex rarefied gas effects and nonequilibrium real gas effects which are beyond the scope of the traditional prediction theory based on the continuum hypothesis and equilibrium assumption. As a typical example, it has been found that the classical Fay-Riddell equation fails to predict the stagnation point heat flux, when the flow is either rarefied or chemical nonequilibrium. In order to design a more general theory covering the rarefied reacting flow cases, an intuitive model is proposed in this paper to describe the nonequilibrium dissociation-recombination flow along the stagnation streamline towards a slightly blunted nose in hypersonic rarefied flows. Some characteristic flow parameters are introduced, and based on these parameters, an explicitly analytical bridging function is established to correct the traditional theory to accurately predict the actual aeroheating performance. It is shown that for a small size nose in medium density flows, the flow at the outer edge of the stagnation point boundary layer could be highly nonequilibrium, and the aeroheating performance is distinguished from that of the big blunt body reentry flows at high altitudes. As a result, when the rarefied gas effects and the nonequilibrium real gas effects are both significant, the classical similarity law could be questionable, and it is inadequate to directly analogize results from the classical blunt body reentry problems to the present new generation sharp-leading vehicles. In addition, the direct simulation Monte Carlo method is also employed to validate the conclusion.

A Low Cost Approach to the Design of Autopilot for Hypersonic Glider

Science.gov (United States)

Liang, Wang; Weihua, Zhang; Ke, Peng; Donghui, Wang

2017-12-01

This paper proposes a novel integrated guidance and control (IGC) approach to improve the autopilot design with low cost for hypersonic glider in dive and pull-up phase. The main objective is robust and adaptive tracking of flight path angle (FPA) under severe flight scenarios. Firstly, the nonlinear IGC model is developed with a second order actuator dynamics. Then the adaptive command filtered back-stepping control is implemented to deal with the large aerodynamics coefficient uncertainties, control surface uncertainties and unmatched time-varying disturbances. For the autopilot, a back-stepping sliding mode control is designed to track the control surface deflection, and a nonlinear differentiator is used to avoid direct differentiating the control input. Through a series of 6-DOF numerical simulations, it’s shown that the proposed scheme successfully cancels out the large uncertainties and disturbances in tracking different kinds of FPA trajectory. The contribution of this paper lies in the application and determination of nonlinear integrated design of guidance and control system for hypersonic glider.

Study of flow control by localized volume heating in hypersonic boundary layers

Science.gov (United States)

Keller, M. A.; Kloker, M. J.; Kirilovskiy, S. V.; Polivanov, P. A.; Sidorenko, A. A.; Maslov, A. A.

2014-12-01

Boundary-layer flow control is a prerequisite for a safe and efficient operation of future hypersonic transport systems. Here, the influence of an electric discharge—modeled by a heat-source term in the energy equation—on laminar boundary-layer flows over a flat plate with zero pressure gradient at Mach 3, 5, and 7 is investigated numerically. The aim was to appraise the potential of electro-gasdynamic devices for an application as turbulence generators in the super- and hypersonic flow regime. The results with localized heat-source elements in boundary layers are compared to cases with roughness elements serving as classical passive trips. The numerical simulations are performed using the commercial code ANSYS FLUENT (by ITAM) and the high-order finite-difference DNS code NS3D (by IAG), the latter allowing for the detailed analysis of laminar flow instability. For the investigated setups with steady heating, transition to turbulence is not observed, due to the Reynolds-number lowering effect of heating.

Soliton generation via continuous stokes acoustic self-scattering of hypersonic waves in a paramagnetic crystal

International Nuclear Information System (INIS)

Bugay, A. N.; Sazonov, S. V.

2008-01-01

A new mechanism is proposed for continuous frequency down-conversion of acoustic waves propagating in a paramagnetic crystal at a low temperature in an applied magnetic field. A transverse hypersonic pulse generating a carrier-free longitudinal strain pulse via nonlinear effects is scattered by the generated pulse. This leads to a Stokes shift in the transverse hypersonic wave proportional to its intensity, and both pulses continue to propagate in the form of a mode-locked soliton. As the transverse-pulse frequency is Stokes shifted, its spectrum becomes narrower. This process can be effectively implemented only if the linear group velocity of the transverse hypersonic pulse equals the phase velocity of the longitudinal strain wave. These velocities are renormalized by spin-phonon coupling and can be made equal by adjusting the magnitude of the applied magnetic field. The transverse structure of the soliton depends on the sign of the group velocity dispersion of the transverse component. When the dispersion is positive, planar solitons can develop whose transverse component has a topological defect of dark vortex type and longitudinal component has a hole. In the opposite case, the formation of two-component acoustic 'bullets' or vortices localized in all directions is possible

Fluid dynamic modeling and numerical simulation of low-density hypersonic flow

Science.gov (United States)

Cheng, H. K.; Wong, Eric Y.

1988-01-01

The concept of a viscous shock-layer and several related versions of continuum theories/methods are examined for their adequacy as a viable framework to study flow physics and aerothermodynamics of relevance to sustained hypersonic flights. Considering the flat plate at angle of attack, or the wedge, as a generic example for the major aerodynamic component of a hypersonic vehicle, the relative importance of the molecular-transport effects behind the shock (in the form of the 'shock slip') and the wall-slip effects are studied. In the flow regime where the shock-transition-zone thickness remains small compared to the shock radius of curvature, a quasi-one-dimensional shock structure under the Burnett/thirteen-moment approximation, as well as particulate/collisional models, can be consistently developed. The fully viscous version of the shock-layer model is shown to provide the crucial boundary condition downstream the shock in this case. The gas-kinetic basis of the continuum description for the flow behind the bow shock, and certain features affecting the non-equilibrium flow chemistry, are also discussed.

DSMC Simulation of Separated Flows About Flared Bodies at Hypersonic Conditions

Science.gov (United States)

Moss, James N.

2000-01-01

This paper describes the results of a numerical study of interacting hypersonic flows at conditions that can be produced in ground-based test facilities. The computations are made with the direct simulation Monte Carlo (DSMC) method of Bird. The focus is on Mach 10 flows about flared axisymmetric configurations, both hollow cylinder flares and double cones. The flow conditions are those for which experiments have been or will be performed in the ONERA R5Ch low-density wind tunnel and the Calspan-University of Buffalo Research Center (CUBRC) Large Energy National Shock (LENS) tunnel. The range of flow conditions, model configurations, and model sizes provides a significant range of shock/shock and shock/boundary layer interactions at low Reynolds number conditions. Results presented will highlight the sensitivity of the calculations to grid resolution, contrast the differences in flow structure for hypersonic cold flows and those of more energetic but still low enthalpy flows, and compare the present results with experimental measurements for surface heating, pressure, and extent of separation.

Concentrated energy addition for active drag reduction in hypersonic flow regime

Science.gov (United States)

Ashwin Ganesh, M.; John, Bibin

2018-01-01

Numerical optimization of hypersonic drag reduction technique based on concentrated energy addition is presented in this study. A reduction in wave drag is realized through concentrated energy addition in the hypersonic flowfield upstream of the blunt body. For the exhaustive optimization presented in this study, an in-house high precision inviscid flow solver has been developed. Studies focused on the identification of "optimum energy addition location" have revealed the existence of multiple minimum drag points. The wave drag coefficient is observed to drop from 0.85 to 0.45 when 50 Watts of energy is added to an energy bubble of 1 mm radius located at 74.7 mm upstream of the stagnation point. A direct proportionality has been identified between energy bubble size and wave drag coefficient. Dependence of drag coefficient on the upstream added energy magnitude is also revealed. Of the observed multiple minimum drag points, the energy deposition point (EDP) that offers minimum wave drag just after a sharp drop in drag is proposed as the most optimum energy addition location.

Numerical simulation as an important tool in developing novel hypersonic technologies

International Nuclear Information System (INIS)

Bocharov, A N; Bityurin, V A; Medin, S A; Naumov, N D; Petrovskiy, V P; Ryabkov, O I; Tatarinov, A V; Teplyakov, I O; Fortov, V E; Balakirev, B A; Golovin, N N; Solomonov, Yu S; Tikhonov, A A; Gryaznov, V K; Iosilevskiy, I L; Evstigneev, N M

2015-01-01

Development of novel hypersonic technologies necessarily requires the development of methods for analyzing a motion of hypervelocity vehicles. This paper could be considered as the initial stage in developing of complex computational model for studying flows around hypervelocity vehicles of arbitrary shape. Essential part of the model is a solution to three-dimensional transport equations for mass, momentum and energy for the medium in the state of both LTE (local thermodynamic equilibrium) and non-LTE. One of the primary requirements to the developed model is the realization on the modern heterogeneous computer systems including both CPU and GPU. The paper presents the first results on numerical simulation of hypersonic flow. The first problem considered is three-dimensional flow around curved body under angle of attack. The performance of heterogeneous 4-GPU computer system is tested. The second problem highlights the capabilities of the developed model to study heat and mass transfer problems. Namely, interior heat problem is considered which takes into account ablation of thermal protection system and variation of the surface shape of the vehicle. (paper)

Radiatively-driven winds: model improvements, ionization balance and the infared spectrum

International Nuclear Information System (INIS)

Castor, J.I.

1979-01-01

Recent improvements to theoretical stellar wind models and the results of empirical modelling of the ionization balance and the infrared continuum are discussed. The model of a wind driven by radiation pressure in spectral lines is improved by accounting for overlap of the driving lines, dependence of ionization balance on density, and stellar rotation. These effects produce a softer velocity law than that given by Castor, Abbott and Klein (1975). The ionization balance in zeta Puppis is shown to agree with that estimated for an optically thick wind at a gas temperature of 60,000 K. The ionization model is not unique. The infrared continuum of zeta Pup measured by Barlow and Cohen is fitted to a cool model with a linear rise of velocity with radius; this fit is also not unique. It is concluded that one should try to find a model that fits several kinds of evidence simultaneously. (Auth.)

Computational Study of Hypersonic Boundary Layer Stability on Cones

Science.gov (United States)

Gronvall, Joel Edwin

Due to the complex nature of boundary layer laminar-turbulent transition in hypersonic flows and the resultant effect on the design of re-entry vehicles, there remains considerable interest in developing a deeper understanding of the underlying physics. To that end, the use of experimental observations and computational analysis in a complementary manner will provide the greatest insights. It is the intent of this work to provide such an analysis for two ongoing experimental investigations. The first focuses on the hypersonic boundary layer transition experiments for a slender cone that are being conducted at JAXA's free-piston shock tunnel HIEST facility. Of particular interest are the measurements of disturbance frequencies associated with transition at high enthalpies. The computational analysis provided for these cases included two-dimensional CFD mean flow solutions for use in boundary layer stability analyses. The disturbances in the boundary layer were calculated using the linear parabolized stability equations. Estimates for transition locations, comparisons of measured disturbance frequencies and computed frequencies, and a determination of the type of disturbances present were made. It was found that for the cases where the disturbances were measured at locations where the flow was still laminar but nearly transitional, that the highly amplified disturbances showed reasonable agreement with the computations. Additionally, an investigation of the effects of finite-rate chemistry and vibrational excitation on flows over cones was conducted for a set of theoretical operational conditions at the HIEST facility. The second study focuses on transition in three-dimensional hypersonic boundary layers, and for this the cone at angle of attack experiments being conducted at the Boeing/AFOSR Mach-6 quiet tunnel at Purdue University were examined. Specifically, the effect of surface roughness on the development of the stationary crossflow instability are investigated

Evaluation of Delivery Costs for External Beam Radiation Therapy and Brachytherapy for Locally Advanced Cervical Cancer Using Time-Driven Activity-Based Costing.

Science.gov (United States)

Bauer-Nilsen, Kristine; Hill, Colin; Trifiletti, Daniel M; Libby, Bruce; Lash, Donna H; Lain, Melody; Christodoulou, Deborah; Hodge, Constance; Showalter, Timothy N

2018-01-01

To evaluate the delivery costs, using time-driven activity-based costing, and reimbursement for definitive radiation therapy for locally advanced cervical cancer. Process maps were created to represent each step of the radiation treatment process and included personnel, equipment, and consumable supplies used to deliver care. Personnel were interviewed to estimate time involved to deliver care. Salary data, equipment purchasing information, and facilities costs were also obtained. We defined the capacity cost rate (CCR) for each resource and then calculated the total cost of patient care according to CCR and time for each resource. Costs were compared with 2016 Medicare reimbursement and relative value units (RVUs). The total cost of radiation therapy for cervical cancer was $12,861.68, with personnel costs constituting 49.8%. Brachytherapy cost $8610.68 (66.9% of total) and consumed 423 minutes of attending radiation oncologist time (80.0% of total). External beam radiation therapy cost $4055.01 (31.5% of total). Personnel costs were higher for brachytherapy than for the sum of simulation and external beam radiation therapy delivery ($4798.73 vs $1404.72). A full radiation therapy course provides radiation oncologists 149.77 RVUs with intensity modulated radiation therapy or 135.90 RVUs with 3-dimensional conformal radiation therapy, with total reimbursement of $23,321.71 and $16,071.90, respectively. Attending time per RVU is approximately 4-fold higher for brachytherapy (5.68 minutes) than 3-dimensional conformal radiation therapy (1.63 minutes) or intensity modulated radiation therapy (1.32 minutes). Time-driven activity-based costing was used to calculate the total cost of definitive radiation therapy for cervical cancer, revealing that brachytherapy delivery and personnel resources constituted the majority of costs. However, current reimbursement policy does not reflect the increased attending physician effort and delivery costs of brachytherapy. We

Properties of Neutrino-driven Ejecta from the Remnant of a Binary Neutron Star Merger: Pure Radiation Hydrodynamics Case

Energy Technology Data Exchange (ETDEWEB)

Fujibayashi, Sho [Yukawa Institute for Theoretical Physics, Kyoto University, Kyoto 606-8502 (Japan); Sekiguchi, Yuichiro [Department of Physics, Toho University, Funabashi, Chiba 274-8510 (Japan); Kiuchi, Kenta; Shibata, Masaru, E-mail: sho.fujibayashi@yukawa.kyoto-u.ac.jp [Center for Gravitational Physics, Yukawa Institute for Theoretical Physics, Kyoto University, Kyoto 606-8502 (Japan)

2017-09-10

We performed general relativistic, long-term, axisymmetric neutrino radiation hydrodynamics simulations for the remnant formed after a binary neutron star merger, which consists of a massive neutron star and a torus surrounding it. As an initial condition, we employ the result derived in a three-dimensional, numerical relativity simulation for the binary neutron star merger. We investigate the properties of neutrino-driven ejecta. Due to the pair-annihilation heating, the dynamics of the neutrino-driven ejecta are significantly modified. The kinetic energy of the ejecta is about two times larger than that in the absence of pair-annihilation heating. This suggests that the pair-annihilation heating plays an important role in the evolution of merger remnants. The relativistic outflow, which is required for driving gamma-ray bursts, is not observed because the specific heating rate around the rotational axis is not sufficiently high, due to the baryon loading caused by the neutrino-driven ejecta from the massive neutron star. We discuss the condition for launching the relativistic outflow and the nucleosynthesis in the ejecta.

Lightweight Ultrahigh Temperature CMC-Encased C/C Structure for Reentry and Hypersonic Applications, Phase I

Data.gov (United States)

National Aeronautics and Space Administration — The reentry spacecraft and hypersonic cruisers of the future will require advanced lightweight thermal protection systems that can provide the dual functionality of...

Minimum weight passive insulation requirements for hypersonic cruise vehicles.

Science.gov (United States)

Ardema, M. D.

1972-01-01

Analytical solutions are derived for two representative cases of the transient heat conduction equation to determine the minimum weight requirements for passive insulation systems of hypersonic cruise vehicles. The cases discussed are the wet wall case with the interior wall temperature held to that of the boiling point of the fuel throughout the flight, and the dry wall case where the heat transferred through the insulation is absorbed by the interior structure whose temperature is allowed to rise.

Simulation of hypersonic shock wave - laminar boundary layer interactions

Science.gov (United States)

Kianvashrad, N.; Knight, D.

2017-06-01

The capability of the Navier-Stokes equations with a perfect gas model for simulation of hypersonic shock wave - laminar boundary layer interactions is assessed. The configuration is a hollow cylinder flare. The experimental data were obtained by Calspan-University of Buffalo (CUBRC) for total enthalpies ranging from 5.07 to 21.85 MJ/kg. Comparison of the computed and experimental surface pressure and heat transfer is performed and the computed §ow¦eld structure is analyzed.

Rarefaction Effects in Hypersonic Aerodynamics

Science.gov (United States)

Riabov, Vladimir V.

2011-05-01

The Direct Simulation Monte-Carlo (DSMC) technique is used for numerical analysis of rarefied-gas hypersonic flows near a blunt plate, wedge, two side-by-side plates, disk, torus, and rotating cylinder. The role of various similarity parameters (Knudsen and Mach numbers, geometrical and temperature factors, specific heat ratios, and others) in aerodynamics of the probes is studied. Important kinetic effects that are specific for the transition flow regime have been found: non-monotonic lift and drag of plates, strong repulsive force between side-by-side plates and cylinders, dependence of drag on torus radii ratio, and the reverse Magnus effect on the lift of a rotating cylinder. The numerical results are in a good agreement with experimental data, which were obtained in a vacuum chamber at low and moderate Knudsen numbers from 0.01 to 10.

A QMU approach for characterizing the operability limits of air-breathing hypersonic vehicles

International Nuclear Information System (INIS)

Iaccarino, Gianluca; Pecnik, Rene; Glimm, James; Sharp, David

2011-01-01

The operability limits of a supersonic combustion engine for an air-breathing hypersonic vehicle are characterized using numerical simulations and an uncertainty quantification methodology. The time-dependent compressible flow equations with heat release are solved in a simplified configuration. Verification, calibration and validation are carried out to assess the ability of the model to reproduce the flow/thermal interactions that occur when the engine unstarts due to thermal choking. quantification of margins and uncertainty (QMU) is used to determine the safe operation region for a range of fuel flow rates and combustor geometries. - Highlights: → In this work we introduce a method to study the operability limits of hypersonic scramjet engines. → The method is based on a calibrated heat release model. → It accounts explicitly for uncertainties due to flight conditions and model correlations. → We examine changes due to the combustor geometry and fuel injection.

Dynamic calibration and validation of an accelerometer force balance for hypersonic lifting models.

Science.gov (United States)

Singh, Prakash; Trivedi, Sharad; Menezes, Viren; Hosseini, Hamid

2014-01-01

An accelerometer-based force balance was designed and developed for the measurement of drag, lift, and rolling moment on a blunt-nosed, flapped delta wing in a short-duration hypersonic shock tunnel. Calibration and validation of the balance were carried out by a convolution technique using hammer pulse test and surface pressure measurements. In the hammer pulse test, a known impulse was applied to the model in the appropriate direction using an impulse hammer, and the corresponding output of the balance (acceleration) was recorded. Fast Fourier Transform (FFT) was operated on the output of the balance to generate a system response function, relating the signal output to the corresponding load input. Impulse response functions for three components of the balance, namely, axial, normal, and angular, were obtained for a range of input load. The angular system response function was corresponding to rolling of the model. The impulse response functions thus obtained, through dynamic calibration, were operated on the output (signals) of the balance under hypersonic aerodynamic loading conditions in the tunnel to get the time history of the unknown aerodynamic forces and moments acting on the model. Surface pressure measurements were carried out on the model using high frequency pressure transducers, and forces and moments were deduced thereon. Tests were carried out at model angles of incidence of 0, 5, 10, and 15 degrees. A good agreement was observed among the results of different experimental methods. The balance developed is a comprehensive force/moment measurement device that can be used on complex, lifting, aerodynamic geometries in ground-based hypersonic test facilities.

Acoustic properties of a porous glass (vycor) at hypersonic frequencies

International Nuclear Information System (INIS)

Levelut, C; Pelous, J

2007-01-01

Brillouin scattering experiments have been performed from 5 to 1600 K in vycor, a porous silica glass. The acoustic velocity and attenuation at hypersonic frequencies are compared to those of bulk silica and others porous silica samples. The experimental evidence for the influence of porosity on the scattering by acoustic waves is compared to calculations. The correlation between internal friction and thermal conductivity at low temperature is discussed

Radiative heat exchange of a meteor body in the approximation of radiant heat conduction

International Nuclear Information System (INIS)

Pilyugin, N.N.; Chernova, T.A.

1986-01-01

The problem of the thermal and dynamic destruction of large meteor bodies moving in planetary atmospheres is fundamental for the clarification of optical observations and anomalous phenomena in the atmosphere, the determination of the physicochemical properties of meteoroids, and the explanation of the fall of remnants of large meteorites. Therefore, it is important to calculate the coefficient of radiant heat exchange (which is the determining factor under these conditions) for large meteor bodies as they move with hypersonic velocities in an atmosphere. The solution of this problem enables one to find the ablation of a meteorite during its aerodynamic heating and to determine the initial conditions for the solution of problems of the breakup of large bodies and their subsequent motion and ablation. Hypersonic flow of an inviscid gas stream over an axisymmetric blunt body is analyzed with allowance for radiative transfer in a thick-thin approximation. The gas-dynamic problem of the flow of an optically thick gas over a large body is solved by the method of asymptotic joined expansions, using a hypersonic approximation and local self-similarity. An equation is obtained for the coefficient of radiant heat exchange and the peculiarities of such heat exchange for meteor bodies of large size are noted

Micromechanical Resonator Driven by Radiation Pressure Force.

Science.gov (United States)

Boales, Joseph A; Mateen, Farrukh; Mohanty, Pritiraj

2017-11-22

Radiation pressure exerted by light on any surface is the pressure generated by the momentum of impinging photons. The associated force - fundamentally, a quantum mechanical aspect of light - is usually too small to be useful, except in large-scale problems in astronomy and astrodynamics. In atomic and molecular optics, radiation pressure can be used to trap or cool atoms and ions. Use of radiation pressure on larger objects such as micromechanical resonators has been so far limited to its coupling to an acoustic mode, sideband cooling, or levitation of microscopic objects. In this Letter, we demonstrate direct actuation of a radio-frequency micromechanical plate-type resonator by the radiation pressure force generated by a standard laser diode at room temperature. Using two independent methods, the magnitude of the resonator's response to forcing by radiation pressure is found to be proportional to the intensity of the incident light.

Trajectory Optimization and Conceptual Study of Small Test Vehicles for Hypersonic Engine Using High-Altitude Balloon

Science.gov (United States)

Tsuchiya, Takeshi; Takenaka, Youichi; Taguchi, Hideyuki; Sawai, Shujiro

Japan Aerospace Exploration Agency, JAXA announced a long-term vision recently. In the vision, JAXA aims to develop hypersonic aircrafts. A pre-cooled turbojet engine has great potential as one of newly developed hypersonic air-breathing engines. We also expect the engine to be installed in space transportation vehicles in future. For combustion test in real flight condition of the engines, JAXA has an experimental plan with a small test vehicle falling from a high-altitude balloon. This paper applies numerical analysis and optimization techniques to conceptual designs of the test vehicle in order to obtain the best configuration and trajectory that can achieve the flight test. The results show helpful knowledge when we design prototype vehicles.

Six sigma tools for a patient safety-oriented, quality-checklist driven radiation medicine department.

Science.gov (United States)

Kapur, Ajay; Potters, Louis

2012-01-01

The purpose of this work was to develop and implement six sigma practices toward the enhancement of patient safety in an electronic, quality checklist-driven, multicenter, paperless radiation medicine department. A quality checklist process map (QPM), stratified into consultation through treatment-completion stages was incorporated into an oncology information systems platform. A cross-functional quality management team conducted quality-function-deployment and define-measure-analyze-improve-control (DMAIC) six sigma exercises with a focus on patient safety. QPM procedures were Pareto-sorted in order of decreasing patient safety risk with failure mode and effects analysis (FMEA). Quantitative metrics for a grouped set of highest risk procedures were established. These included procedural delays, associated standard deviations and six sigma Z scores. Baseline performance of the QPM was established over the previous year of usage. Data-driven analysis led to simplification, standardization, and refinement of the QPM with standard deviation, slip-day reduction, and Z-score enhancement goals. A no-fly policy (NFP) for patient safety was introduced at the improve-control DMAIC phase, with a process map interlock imposed on treatment initiation in the event of FMEA-identified high-risk tasks being delayed or not completed. The NFP was introduced in a pilot phase with specific stopping rules and the same metrics used for performance assessments. A custom root-cause analysis database was deployed to monitor patient safety events. Relative to the baseline period, average slip days and standard deviations for the risk-enhanced QPM procedures improved by over threefold factors in the NFP period. The Z scores improved by approximately 20%. A trend for proactive delays instead of reactive hard stops was observed with no adverse effects of the NFP. The number of computed potential no-fly delays per month dropped from 60 to 20 over a total of 520 cases. The fraction of computed

Nonspherical Radiation Driven Wind Models Applied to Be Stars

Science.gov (United States)

Arauxo, F. X.

1990-11-01

ABSTRACT. In this work we present a model for the structure of a radiatively driven wind in the meridional plane of a hot star. Rotation effects and simulation of viscous forces were included in the motion equations. The line radiation force is considered with the inclusion of the finite disk correction in self-consistent computations which also contain gravity darkening as well as distortion of the star by rotation. An application to a typical BlV star leads to mass-flux ratios between equator and pole of the order of 10 and mass loss rates in the range 5.l0 to Mo/yr. Our envelope models are flattened towards the equator and the wind terminal velocities in that region are rather high (1000 Km/s). However, in the region near the star the equatorial velocity field is dominated by rotation. RESUMEN. Se presenta un modelo de la estructura de un viento empujado radiativamente en el plano meridional de una estrella caliente. Se incluyeron en las ecuaciones de movimiento los efectos de rotaci6n y la simulaci6n de fuerzas viscosas. Se consider6 la fuerza de las lineas de radiaci6n incluyendo la correcci6n de disco finito en calculos autoconsistentes los cuales incluyen oscurecimiento gravitacional asi como distorsi6n de la estrella por rotaci6n. La aplicaci6n a una estrella tipica BlV lleva a cocientes de flujo de masa entre el ecuador y el polo del orden de 10 de perdida de masa en el intervalo 5.l0 a 10 Mo/ano. Nuestros modelos de envolvente estan achatados hacia el ecuador y las velocidads terminales del viento en esa regi6n son bastante altas (1000 Km/s). Sin embargo, en la regi6n cercana a la estrella el campo de velocidad ecuatorial esta dominado por la rotaci6n. Key words: STARS-BE -- STARS-WINDS

Role of Turbulent Prandtl Number on Heat Flux at Hypersonic Mach Number

Science.gov (United States)

Xiao, X.; Edwards, J. R.; Hassan, H. A.

2004-01-01

Present simulation of turbulent flows involving shock wave/boundary layer interaction invariably overestimates heat flux by almost a factor of two. One possible reason for such a performance is a result of the fact that the turbulence models employed make use of Morkovin's hypothesis. This hypothesis is valid for non-hypersonic Mach numbers and moderate rates of heat transfer. At hypersonic Mach numbers, high rates of heat transfer exist in regions where shock wave/boundary layer interactions are important. As a result, one should not expect traditional turbulence models to yield accurate results. The goal of this investigation is to explore the role of a variable Prandtl number formulation in predicting heat flux in flows dominated by strong shock wave/boundary layer interactions. The intended applications involve external flows in the absence of combustion such as those encountered in supersonic inlets. This can be achieved by adding equations for the temperature variance and its dissipation rate. Such equations can be derived from the exact Navier-Stokes equations. Traditionally, modeled equations are based on the low speed energy equation where the pressure gradient term and the term responsible for energy dissipation are ignored. It is clear that such assumptions are not valid for hypersonic flows. The approach used here is based on the procedure used in deriving the k-zeta model, in which the exact equations that governed k, the variance of velocity, and zeta, the variance of vorticity, were derived and modeled. For the variable turbulent Prandtl number, the exact equations that govern the temperature variance and its dissipation rate are derived and modeled term by term. The resulting set of equations are free of damping and wall functions and are coordinate-system independent. Moreover, modeled correlations are tensorially consistent and invariant under Galilean transformation. The final set of equations will be given in the paper.

Computational investigations of blunt body drag-reduction spikes in hypersonic flows

International Nuclear Information System (INIS)

Kamran, N.; Zahir, S.; Khan, M.A.

2003-01-01

Drag is an important parameter in the designing of high-speed vehicles. Such vehicles include hypervelocity projectiles, reentry modules, and hypersonic aircrafts. Therefore, there exists an active or passive technique to reduce drag due to the high pressures at nosetip region of the vehicle. Drag can be reduced by attaching a forward facing spike on the nose of the vehicle. The present study reviews and deals with the CFD analysis made on a standard blunt body to reduce aerodynamic drag due to the attachment of forward facing spikes for High-Speed vehicles. Different spike lengths have been examined to study the forebody flowfield. The investigation concludes that spikes are an effective way to reduce the aerodynamic drag due to reduced dynamic pressure on the nose caused by the separated flow on the spikes. With the accomplishment of confidence on computational data, study was extended in hypersonic Mach range with a drag prediction accuracy of ± 10%. In the present work, viscous fluid dynamics studies were performed for a complete freestream Mach number range of 5.0, 6.0, 7.0 and 8.0 for different spike lengths and zero degree angle of attack. (author)

PIV measurements in two hypersonic shock wave / turbulent boundary layer interactions

Science.gov (United States)

Schreyer, Anne-Marie; Williams, Owen; Smits, Alexander J.

2017-11-01

Particle Image Velocimetry measurements were performed to study two compression corner interactions in hypersonic flow. The experiments, carried out at Mach 7.2 and at a Reynolds number based on momentum thickness of 3500, included mean flow surveys as well as turbulence measurements in the near-field of the interaction. For the 8° compression corner, the flow remained attached, and for the 33° compression corner a large separation bubble formed. For the attached case, the influence of the shock wave on the streamwise turbulence intensities is weak, but the wall-normal component and the Reynolds shear stress show considerable amplification. In the fully separated case, both the streamwise and wall normal velocity fluctuations, as well as the Reynolds shear stresses, show strong amplification across the interaction. In contrast with the behavior in the attached case, equilibrium flow is approached much more rapidly in the separated case. Turbulence measurements in such complex hypersonic flows are far from trivial, with particle frequency response limitations often significantly reducing the measured wall-normal turbulence. We will therefore discuss these influences on overall data quality as well as the interpretation of flow physics based on these results.

Investigation of turbulence models with compressibility corrections for hypersonic boundary flows

Directory of Open Access Journals (Sweden)

Han Tang

2015-12-01

Full Text Available The applications of pressure work, pressure-dilatation, and dilatation-dissipation (Sarkar, Zeman, and Wilcox models to hypersonic boundary flows are investigated. The flat plate boundary layer flows of Mach number 5–11 and shock wave/boundary layer interactions of compression corners are simulated numerically. For the flat plate boundary layer flows, original turbulence models overestimate the heat flux with Mach number high up to 10, and compressibility corrections applied to turbulence models lead to a decrease in friction coefficients and heating rates. The pressure work and pressure-dilatation models yield the better results. Among the three dilatation-dissipation models, Sarkar and Wilcox corrections present larger deviations from the experiment measurement, while Zeman correction can achieve acceptable results. For hypersonic compression corner flows, due to the evident increase of turbulence Mach number in separation zone, compressibility corrections make the separation areas larger, thus cannot improve the accuracy of calculated results. It is unreasonable that compressibility corrections take effect in separation zone. Density-corrected model by Catris and Aupoix is suitable for shock wave/boundary layer interaction flows which can improve the simulation accuracy of the peak heating and have a little influence on separation zone.

First results of radiation-driven, layered deuterium-tritium implosions with a 3-shock adiabat-shaped drive at the National Ignition Facility

Energy Technology Data Exchange (ETDEWEB)

Smalyuk, V. A.; Robey, H. F.; Döppner, T.; Jones, O. S.; Milovich, J. L.; Bachmann, B.; Baker, K. L.; Berzak Hopkins, L. F.; Bond, E.; Callahan, D. A.; Casey, D. T.; Celliers, P. M.; Cerjan, C.; Clark, D. S.; Dixit, S. N.; Edwards, M. J.; Haan, S. W.; Hamza, A. V.; Hurricane, O. A.; Jancaitis, K. S. [Lawrence Livermore National Laboratory, Livermore, California 94550 (United States); and others

2015-08-15

Radiation-driven, layered deuterium-tritium plastic capsule implosions were carried out using a new, 3-shock “adiabat-shaped” drive on the National Ignition Facility. The purpose of adiabat shaping is to use a stronger first shock, reducing hydrodynamic instability growth in the ablator. The shock can decay before reaching the deuterium-tritium fuel leaving it on a low adiabat and allowing higher fuel compression. The fuel areal density was improved by ∼25% with this new drive compared to similar “high-foot” implosions, while neutron yield was improved by more than 4 times, compared to “low-foot” implosions driven at the same compression and implosion velocity.

Study of effect of a smooth hump on hypersonic boundary layer instability

Science.gov (United States)

Park, Donghun; Park, Seung O.

2016-12-01

Effect of a two-dimensional smooth hump on linear instability of hypersonic boundary layer is studied by using parabolized stability equations. Linear evolution of mode S over a hump is analyzed for Mach 4.5 and 5.92 flat plate and Mach 7.1 sharp cone boundary layers. Mean flow for stability analysis is obtained by solving the parabolized Navier-Stokes equations. Hump with height smaller than local boundary layer thickness is considered. The case of flat plate and sharp cone without the hump are also studied to provide comparable data. For flat plate boundary layers, destabilization and stabilization effect is confirmed for hump located at upstream and downstream of synchronization point, respectively. Results of parametric studies to examine the effect of hump height, location, etc., are also given. For sharp cone boundary layer, stabilization influence of hump is also identified for a specific range of frequency. Stabilization influence of hump on convective instability of mode S is found to be a possible cause of previous experimental observations of delaying transition in hypersonic boundary layers.

Wind-US Code Physical Modeling Improvements to Complement Hypersonic Testing and Evaluation

Science.gov (United States)

Georgiadis, Nicholas J.; Yoder, Dennis A.; Towne, Charles S.; Engblom, William A.; Bhagwandin, Vishal A.; Power, Greg D.; Lankford, Dennis W.; Nelson, Christopher C.

2009-01-01

This report gives an overview of physical modeling enhancements to the Wind-US flow solver which were made to improve the capabilities for simulation of hypersonic flows and the reliability of computations to complement hypersonic testing. The improvements include advanced turbulence models, a bypass transition model, a conjugate (or closely coupled to vehicle structure) conduction-convection heat transfer capability, and an upgraded high-speed combustion solver. A Mach 5 shock-wave boundary layer interaction problem is used to investigate the benefits of k- s and k-w based explicit algebraic stress turbulence models relative to linear two-equation models. The bypass transition model is validated using data from experiments for incompressible boundary layers and a Mach 7.9 cone flow. The conjugate heat transfer method is validated for a test case involving reacting H2-O2 rocket exhaust over cooled calorimeter panels. A dual-mode scramjet configuration is investigated using both a simplified 1-step kinetics mechanism and an 8-step mechanism. Additionally, variations in the turbulent Prandtl and Schmidt numbers are considered for this scramjet configuration.

Artist Concept of X-43A/Hyper-X Hypersonic Experimental Research Vehicle in Flight

Science.gov (United States)

1998-01-01

An artist's conception of the X-43A Hypersonic Experimental Vehicle, or 'Hyper-X' in flight. The X-43A was developed to flight test a dual-mode ramjet/scramjet propulsion system at speeds from Mach 7 up to Mach 10 (7 to 10 times the speed of sound, which varies with temperature and altitude). Hyper-X, the flight vehicle for which is designated as X-43A, is an experimental flight-research program seeking to demonstrate airframe-integrated, 'air-breathing' engine technologies that promise to increase payload capacity for future vehicles, including hypersonic aircraft (faster than Mach 5) and reusable space launchers. This multiyear program is currently underway at NASA Dryden Flight Research Center, Edwards, California. The Hyper-X schedule calls for its first flight later this year (2000). Hyper-X is a joint program, with Dryden sharing responsibility with NASA's Langley Research Center, Hampton, Virginia. Dryden's primary role is to fly three unpiloted X-43A research vehicles to validate engine technologies and hypersonic design tools as well as the hypersonic test facility at Langley. Langley manages the program and leads the technology development effort. The Hyper-X Program seeks to significantly expand the speed boundaries of air-breathing propulsion by being the first aircraft to demonstrate an airframe-integrated, scramjet-powered free flight. Scramjets (supersonic-combustion ramjets) are ramjet engines in which the airflow through the whole engine remains supersonic. Scramjet technology is challenging because only limited testing can be performed in ground facilities. Long duration, full-scale testing requires flight research. Scramjet engines are air-breathing, capturing their oxygen from the atmosphere. Current spacecraft, such as the Space Shuttle, are rocket powered, so they must carry both fuel and oxygen for propulsion. Scramjet technology-based vehicles need to carry only fuel. By eliminating the need to carry oxygen, future hypersonic vehicles will

A local-velocity meter for hypersonic plasma jet

International Nuclear Information System (INIS)

Nyazev, A.A.; Lerner, N.B.; Svinolupov, K.I.

1985-01-01

This paper describes a system for a resonant laser Doppler meter for the local velocity in a hypersonic plasma flow. Preliminary test results on the prototype are reported for a jet of air containing sodium at 1100 degrees K, air pressure in the working region 20-200 Pa, and jet speed 6-8 km/sec. Measured speeds agree with theoretical predictions. The prototype and the method do not impose constraints on the working conditions but can be extended to wide ranges in temperature and pressure, such as ones in which the line width does not exceed the Doppler shift

Radiation and detection of gravitational waves in laboratory conditions

International Nuclear Information System (INIS)

Bogolyubov, P.N.; Pisarev, A.F.; Shavokhina, N.S.

1981-01-01

Two variants are proposed and analyzed for an experiment on radiation and detection of gravitational waves in laboratory conditions in the optical and superhigh frequency range (band). In the first variant the laser light is parametrically transformed to the gravitational wave in the optical-inhomogeneous medium. The gravitational flux produced is registered by the inverse parametric transformation of the gravitational to light wave. In the second variant the radiation of gravitational waves is realized through hypersonic oscillations in piezocrystals, and the reception of waves is made by the superconducting coaxial resonator in which the gravitational wave resonantly transforms into the electromag= . netic wave. The analysis performed testifies to the possibility of an experiment of this type at the present time [ru

Electromagnetically driven radiative shocks and their measurements

International Nuclear Information System (INIS)

Kondo, K.; Watanabe, M.; Nakajima, M.; Kawamura, T.; Horioka, K.

2005-01-01

Experimental results on a generation of strong shocks in a compact pulse power device are reported. The characteristics of strong shocks are different from hydrodynamical shocks' because they depend on not only collisions but radiation processes. Radiative shocks are relevant to high energy density phenomena such as the explosions of supernovae. When initial pressure is lower than about 50 mtorr, an interesting structure is confirmed at the shock front, which might indicate a phenomenon proceeded by the radiative process. (author)

CFD application to supersonic/hypersonic inlet airframe integration. [computational fluid dynamics (CFD)

Science.gov (United States)

Benson, Thomas J.

1988-01-01

Supersonic external compression inlets are introduced, and the computational fluid dynamics (CFD) codes and tests needed to study flow associated with these inlets are outlined. Normal shock wave turbulent boundary layer interaction is discussed. Boundary layer control is considered. Glancing sidewall shock interaction is treated. The CFD validation of hypersonic inlet configurations is explained. Scramjet inlet modules are shown.

Current delivery and radiation yield in plasma flow switch-driven implosions

International Nuclear Information System (INIS)

Baker, W.L.; Degnan, J.H.; Beason, J.D.

1995-01-01

Vacuum inductive-store, plasma flow switch-driven implosion experiments have been performed using the Shiva Star capacitor bank (1300 μf, 3 nH, 120 kV, 9.4 MJ). A coaxial plasma gun arrangement is employed to store magnetic energy in the vacuum volume upstream of a dynamic discharge during the 3- to 4-μs rise of current from the capacitor bank. Motion of the discharge off the end of the inner conductor of the gun releases this energy to implode a coaxial cylindrical foil. The implosion loads are 5-cm-radius, 2-cm-long, 200 to 400 μg/cm 2 cylinders of aluminum or aluminized Formvar. With 5 MJ stored initially in the capacitor bank, more than 9 MA are delivered to the implosion load with a rise time of nearly 200 ns. The subsequent implosion results in a radiation output of 0.95 MJ at a power exceeding 5 TW (assuming isotropic emission). Experimental results and related two-dimensional magnetohydrodynamic simulations are discussed. 10 refs., 12 figs

Radiation therapy with laser-driven accelerated particle beams: physical dosimetry and spatial dose distribution

Energy Technology Data Exchange (ETDEWEB)

Reinhardt, Sabine; Assmann, Walter [Ludwig-Maximilians Universitaet Muenchen (Germany); Kneschaurek, Peter; Wilkens, Jan [MRI, Technische Universitaet Muenchen (Germany)

2011-07-01

One of the main goals of the Munich Centre for Advanced Photonics (MAP) is the application of laser driven accelerated (LDA) particle beams for radiation therapy. Due to the unique acceleration process ultrashort particle pulses of high intensity (> 10{sup 7} particles /cm{sup 2}/ns) are generated, which makes online detection an ambitious task. So far, state of the art detection of laser accelerated ion pulses are non-electronic detectors like radiochromic films (RCF), imaging plates (IP) or nuclear track detectors (e.g. CR39). All these kind of detectors are offline detectors requiring several hours of processing time. For this reason they are not qualified for an application in radiation therapy where quantitative real time detection of the beam is an essential prerequisite. Therefore we are investigating pixel detectors for real time monitoring of LDA particle pulses. First tests of commercially available systems with 8-20 MeV protons are presented. For radiobiological experiments second generation Gafchromic films (EBT2) have been calibrated with protons of 12 and 20 MeV for a dose range of 0.3-10 Gy. Dose verification in proton irradiation of subcutaneous tumours in mice was successfully accomplished using these films.

Theory of radiatively driven stellar winds. I. A physical interpretation

International Nuclear Information System (INIS)

Abbott, D.C.

1980-01-01

This series of papers extends the line-driven wind theory of Castor, Abbott, and Klein (CAK). The present paper develops a physical interpretation of line-driven flows using analytic methods. Numerical results will follow in two subsequent papers

LES of hypersonic flow over a 3D single-fin

OpenAIRE

Fang, J.; Yao, Y.; Lu, L.; Zheng, Y.

2015-01-01

LES of hypersonic flow passing a 3D single-fin at Mach 5 and Re∞=3.7×107/m was conducted using a newly developed 7th-order low-dissipation monotonicity-preserving NS solver with dynamic Smagorinsky subgrid model. The simulation captures salient flow phenome such as shock systems, flow separation structures, and turbulence characteristics. It was found that in the reverse flow region, the streamwise elongated coherent structures are regenerated beneath the main separation vortex, almost immedi...

Validation of contour-driven thin-plate splines for tracking fraction-to-fraction changes in anatomy and radiation therapy dose mapping

International Nuclear Information System (INIS)

Schaly, B; Bauman, G S; Battista, J J; Dyk, J Van

2005-01-01

The goal of this study is to validate a deformable model using contour-driven thin-plate splines for application to radiation therapy dose mapping. Our testing includes a virtual spherical phantom as well as real computed tomography (CT) data from ten prostate cancer patients with radio-opaque markers surgically implanted into the prostate and seminal vesicles. In the spherical mathematical phantom, homologous control points generated automatically given input contour data in CT slice geometry were compared to homologous control point placement using analytical geometry as the ground truth. The dose delivered to specific voxels driven by both sets of homologous control points were compared to determine the accuracy of dose tracking via the deformable model. A 3D analytical spherically symmetric dose distribution with a dose gradient of ∼10% per mm was used for this phantom. This test showed that the uncertainty in calculating the delivered dose to a tissue element depends on slice thickness and the variation in defining homologous landmarks, where dose agreement of 3-4% in high dose gradient regions was achieved. In the patient data, radio-opaque marker positions driven by the thin-plate spline algorithm were compared to the actual marker positions as identified in the CT scans. It is demonstrated that the deformable model is accurate (∼2.5 mm) to within the intra-observer contouring variability. This work shows that the algorithm is appropriate for describing changes in pelvic anatomy and for the dose mapping application with dose gradients characteristic of conformal and intensity modulated radiation therapy

Validation of contour-driven thin-plate splines for tracking fraction-to-fraction changes in anatomy and radiation therapy dose mapping.

Science.gov (United States)

Schaly, B; Bauman, G S; Battista, J J; Van Dyk, J

2005-02-07

The goal of this study is to validate a deformable model using contour-driven thin-plate splines for application to radiation therapy dose mapping. Our testing includes a virtual spherical phantom as well as real computed tomography (CT) data from ten prostate cancer patients with radio-opaque markers surgically implanted into the prostate and seminal vesicles. In the spherical mathematical phantom, homologous control points generated automatically given input contour data in CT slice geometry were compared to homologous control point placement using analytical geometry as the ground truth. The dose delivered to specific voxels driven by both sets of homologous control points were compared to determine the accuracy of dose tracking via the deformable model. A 3D analytical spherically symmetric dose distribution with a dose gradient of approximately 10% per mm was used for this phantom. This test showed that the uncertainty in calculating the delivered dose to a tissue element depends on slice thickness and the variation in defining homologous landmarks, where dose agreement of 3-4% in high dose gradient regions was achieved. In the patient data, radio-opaque marker positions driven by the thin-plate spline algorithm were compared to the actual marker positions as identified in the CT scans. It is demonstrated that the deformable model is accurate (approximately 2.5 mm) to within the intra-observer contouring variability. This work shows that the algorithm is appropriate for describing changes in pelvic anatomy and for the dose mapping application with dose gradients characteristic of conformal and intensity modulated radiation therapy.

Hypersonic Poration: A New Versatile Cell Poration Method to Enhance Cellular Uptake Using a Piezoelectric Nano-Electromechanical Device.

Science.gov (United States)

Zhang, Zhixin; Wang, Yanyan; Zhang, Hongxiang; Tang, Zifan; Liu, Wenpeng; Lu, Yao; Wang, Zefang; Yang, Haitao; Pang, Wei; Zhang, Hao; Zhang, Daihua; Duan, Xuexin

2017-05-01

Efficient delivery of genes and therapeutic agents to the interior of the cell is critical for modern biotechnology. Herein, a new type of chemical-free cell poration method-hypersonic poration-is developed to improve the cellular uptake, especially the nucleus uptake. The hypersound (≈GHz) is generated by a designed piezoelectric nano-electromechanical resonator, which directly induces normal/shear stress and "molecular bombardment" effects on the bilayer membranes, and creates reversible temporal nanopores improving the membrane permeability. Both theory analysis and cellular uptake experiments of exogenous compounds prove the high delivery efficiency of hypersonic poration. Since target molecules in cells are accumulated with the treatment, the delivered amount can be controlled by tuning the treatment time. Furthermore, owing to the intrinsic miniature of the resonator, localized drug delivery at a confined spatial location and tunable arrays of the resonators that are compatible with multiwell plate can be achieved. The hypersonic poration method shows great delivery efficacy combined with advantage of scalability, tunable throughput, and simplification in operation and provides a potentially powerful strategy in the field of molecule delivery, cell transfection, and gene therapy. © 2017 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim.

Radiation yield from SHIVA Star plasma flow switch driven fast liner implosions

International Nuclear Information System (INIS)

Degnan, J.H.; Baker, W.L.; Beason, J.D.

1987-01-01

A 2.5 Terawatt 0.5 MJ isotropic equivalent radiation yield was obtained in a SHIVA Star plasma flow switch driven fast liner implosion. The 1313 μF 80 kV discharge delivered 13 MA to a coaxial vacuum inductive store with a plasma armature. Over 9.4 MA current was plasma flow switched to the implosion load (>90% of the gun muzzle current at that time). The load wa a 5 cm radius, 2 cm tall, 200 μg/cm/sup 2/ aluminum plated Formvar cylindrical foil. The radiation pulse was measured with an array of seven X-ray diodes (XRDs). The XRDs all had aluminum photocathodes, a variety of filters and nickel mesh to reduce the incident X-ray photon flux to avoid Child-Langmuir saturation. The filters were chosen so that the authors had seven different diode response functions covering the energy range from 15 eV to about 3 keV. The filters were mounted remote (about 30 cm) from the XRDs. The anode mesh served as part of the mesh array. The distance between meshes was greater than 10 cm. Each XRD had a 5 cm diameter cathode with an aperture limited to a 2 cm diameter. The XRD anode-cathode gap was 1 cm and the bias was 5 kV. The theoretical Child-Langmuir saturation signal was 125 V with 50 Ω termination. The maximum observed signal was 75 V

Recent advances in laser-driven neutron sources

Science.gov (United States)

Alejo, A.; Ahmed, H.; Green, A.; Mirfayzi, S. R.; Borghesi, M.; Kar, S.

2016-11-01

Due to the limited number and high cost of large-scale neutron facilities, there has been a growing interest in compact accelerator-driven sources. In this context, several potential schemes of laser-driven neutron sources are being intensively studied employing laser-accelerated electron and ion beams. In addition to the potential of delivering neutron beams with high brilliance, directionality and ultra-short burst duration, a laser-driven neutron source would offer further advantages in terms of cost-effectiveness, compactness and radiation confinement by closed-coupled experiments. Some of the recent advances in this field are discussed, showing improvements in the directionality and flux of the laser-driven neutron beams.

Hyper-X and Pegasus Launch Vehicle: A Three-Foot Model of the Hypersonic Experimental Research Vehic

Science.gov (United States)

1997-01-01

The configuration of the X-43A Hypersonic Experimental Research Vehicle, or Hyper-X, attached to a Pegasus launch vehicle is displayed in this three-foot-long model at NASA's Dryden Flight Research Center, Edwards, California. Hyper-X, the flight vehicle for which is designated as X-43A, is an experimental flight-research program seeking to demonstrate airframe-integrated, 'air-breathing' engine technologies that promise to increase payload capacity for future vehicles, including hypersonic aircraft (faster than Mach 5) and reusable space launchers. This multiyear program is currently underway at NASA Dryden Flight Research Center, Edwards, California. The Hyper-X schedule calls for its first flight later this year (2000). Hyper-X is a joint program, with Dryden sharing responsibility with NASA's Langley Research Center, Hampton, Virginia. Dryden's primary role is to fly three unpiloted X-43A research vehicles to validate engine technologies and hypersonic design tools as well as the hypersonic test facility at Langley. Langley manages the program and leads the technology development effort. The Hyper-X Program seeks to significantly expand the speed boundaries of air-breathing propulsion by being the first aircraft to demonstrate an airframe-integrated, scramjet-powered free flight. Scramjets (supersonic-combustion ramjets) are ramjet engines in which the airflow through the whole engine remains supersonic. Scramjet technology is challenging because only limited testing can be performed in ground facilities. Long duration, full-scale testing requires flight research. Scramjet engines are air-breathing, capturing their oxygen from the atmosphere. Current spacecraft, such as the Space Shuttle, are rocket powered, so they must carry both fuel and oxygen for propulsion. Scramjet technology-based vehicles need to carry only fuel. By eliminating the need to carry oxygen, future hypersonic vehicles will be able to carry heavier payloads. Another unique aspect of the X-43

Terminal Sliding Mode Control with Unidirectional Auxiliary Surfaces for Hypersonic Vehicles Based on Adaptive Disturbance Observer

Directory of Open Access Journals (Sweden)

Naibao He

2015-01-01

Full Text Available A novel flight control scheme is proposed using the terminal sliding mode technique, unidirectional auxiliary surfaces and the disturbance observer model. These proposed dynamic attitude control systems can improve control performance of hypersonic vehicles despite uncertainties and external disturbances. The terminal attractor is employed to improve the convergence rate associated with the critical damping characteristics problem noted in short-period motions of hypersonic vehicles. The proposed robust attitude control scheme uses a dynamic terminal sliding mode with unidirectional auxiliary surfaces. The nonlinear disturbance observer is designed to estimate system uncertainties and external disturbances. The output of the disturbance observer aids the robust adaptive control scheme and improves robust attitude control performance. Finally, simulation results are presented to illustrate the effectiveness of the proposed terminal sliding mode with unidirectional auxiliary surfaces.

Anisotropic lattice expansion of three-dimensional colloidal crystals and its impact on hypersonic phonon band gaps.

Science.gov (United States)

Wu, Songtao; Zhu, Gaohua; Zhang, Jin S; Banerjee, Debasish; Bass, Jay D; Ling, Chen; Yano, Kazuhisa

2014-05-21

We report anisotropic expansion of self-assembled colloidal polystyrene-poly(dimethylsiloxane) crystals and its impact on the phonon band structure at hypersonic frequencies. The structural expansion was achieved by a multistep infiltration-polymerization process. Such a process expands the interplanar lattice distance 17% after 8 cycles whereas the in-plane distance remains unaffected. The variation of hypersonic phonon band structure induced by the anisotropic lattice expansion was recorded by Brillouin measurements. In the sample before expansion, a phononic band gap between 3.7 and 4.4 GHz is observed; after 17% structural expansion, the gap is shifted to a lower frequency between 3.5 and 4.0 GHz. This study offers a facile approach to control the macroscopic structure of colloidal crystals with great potential in designing tunable phononic devices.

Hypersonic aerodynamics on thin bodies with interaction and upstream influence

OpenAIRE

Smith, F. T.; Khorrami, A. F.

1994-01-01

In the fundamental configuration studied here, a steady hypersonic free stream flows over a thin sharp aligned airfoil or flat plate with a leading-edge shock wave, and the flow field in the shock layer (containing a viscous and an inviscid layer) is steady laminar and two-dimensional, for a perfect gas without real and high-temperature gas effects. The viscous and inviscid layers are analysed and computed simultaneously in the region from the leading edge to the trailing edge, including the ...

Pressure Fluctuations Induced by a Hypersonic Turbulent Boundary Layer

Science.gov (United States)

Duan, Lian; Choudhari, Meelan M.; Zhang, Chao

2016-01-01

Direct numerical simulations (DNS) are used to examine the pressure fluctuations generated by a spatially-developed Mach 5.86 turbulent boundary layer. The unsteady pressure field is analyzed at multiple wall-normal locations, including those at the wall, within the boundary layer (including inner layer, the log layer, and the outer layer), and in the free stream. The statistical and structural variations of pressure fluctuations as a function of wall-normal distance are highlighted. Computational predictions for mean velocity pro les and surface pressure spectrum are in good agreement with experimental measurements, providing a first ever comparison of this type at hypersonic Mach numbers. The simulation shows that the dominant frequency of boundary-layer-induced pressure fluctuations shifts to lower frequencies as the location of interest moves away from the wall. The pressure wave propagates with a speed nearly equal to the local mean velocity within the boundary layer (except in the immediate vicinity of the wall) while the propagation speed deviates from the Taylor's hypothesis in the free stream. Compared with the surface pressure fluctuations, which are primarily vortical, the acoustic pressure fluctuations in the free stream exhibit a significantly lower dominant frequency, a greater spatial extent, and a smaller bulk propagation speed. The freestream pressure structures are found to have similar Lagrangian time and spatial scales as the acoustic sources near the wall. As the Mach number increases, the freestream acoustic fluctuations exhibit increased radiation intensity, enhanced energy content at high frequencies, shallower orientation of wave fronts with respect to the flow direction, and larger propagation velocity.

Photogrammetry of a Hypersonic Inflatable Aerodynamic Decelerator

Science.gov (United States)

Kushner, Laura Kathryn; Littell, Justin D.; Cassell, Alan M.

2013-01-01

In 2012, two large-scale models of a Hypersonic Inflatable Aerodynamic decelerator were tested in the National Full-Scale Aerodynamic Complex at NASA Ames Research Center. One of the objectives of this test was to measure model deflections under aerodynamic loading that approximated expected flight conditions. The measurements were acquired using stereo photogrammetry. Four pairs of stereo cameras were mounted inside the NFAC test section, each imaging a particular section of the HIAD. The views were then stitched together post-test to create a surface deformation profile. The data from the photogram- metry system will largely be used for comparisons to and refinement of Fluid Structure Interaction models. This paper describes how a commercial photogrammetry system was adapted to make the measurements and presents some preliminary results.

Schlieren Visualization of the Energy Addition by Multi Laser Pulse in Hypersonic Flow

International Nuclear Information System (INIS)

Oliveira, A. C.; Minucci, M. A. S.; Toro, P. G. P.; Chanes, J. B. Jr; Myrabo, L. N.

2008-01-01

The experimental results of the energy addition by multi laser pulse in Mach 7 hypersonic flow are presented. Two high power pulsed CO 2 TEA lasers (TEA1 5.5 J, TEA2 3.9 J) were assembled sharing the same optical cavity to generate the plasma upstream of a hemispherical model installed in the tunnel test section. The lasers can be triggered with a selectable time delay and in the present report the results obtained with delay between 30 μs and 80 μs are shown. The schlieren technique associated with a high speed camera was used to accomplish the influence of the energy addition in the mitigation of the shock wave formed on the model surface by the hypersonic flow. A piezoelectric pressure transducer was used to obtain the time history of the impact pressure at stagnation point of the model and the pressure reduction could be measured. The total recovery of the shock wave between pulses as well as the prolonged effect of the mitigation without recovery was observed by changing the delay

Space Shuttle and Hypersonic Entry

Science.gov (United States)

Campbell, Charles H.; Gerstenmaier, William H.

2014-01-01

Fifty years of human spaceflight have been characterized by the aerospace operations of the Soyuz, of the Space Shuttle and, more recently, of the Shenzhou. The lessons learned of this past half decade are important and very significant. Particularly interesting is the scenario that is downstream from the retiring of the Space Shuttle. A number of initiatives are, in fact, emerging from in the aftermath of the decision to terminate the Shuttle program. What is more and more evident is that a new era is approaching: the era of the commercial usage and of the commercial exploitation of space. It is probably fair to say, that this is the likely one of the new frontiers of expansion of the world economy. To make a comparison, in the last 30 years our economies have been characterized by the digital technologies, with examples ranging from computers, to cellular phones, to the satellites themselves. Similarly, the next 30 years are likely to be characterized by an exponential increase of usage of extra atmospheric resources, as a result of more economic and efficient way to access space, with aerospace transportation becoming accessible to commercial investments. We are witnessing the first steps of the transportation of future generation that will drastically decrease travel time on our Planet, and significantly enlarge travel envelope including at least the low Earth orbits. The Steve Jobs or the Bill Gates of the past few decades are being replaced by the aggressive and enthusiastic energy of new entrepreneurs. It is also interesting to note that we are now focusing on the aerospace band, that lies on top of the aeronautical shell, and below the low Earth orbits. It would be a mistake to consider this as a known envelope based on the evidences of the flights of Soyuz, Shuttle and Shenzhou. Actually, our comprehension of the possible hypersonic flight regimes is bounded within really limited envelopes. The achievement of a full understanding of the hypersonic flight

The NASA Ames Hypersonic Combustor-Model Inlet CFD Simulations and Experimental Comparisons

Science.gov (United States)

Venkatapathy, E.; Tokarcik-Polsky, S.; Deiwert, G. S.; Edwards, Thomas A. (Technical Monitor)

1995-01-01

Computations have been performed on a three-dimensional inlet associated with the NASA Ames combustor model for the hypersonic propulsion experiment in the 16-inch shock tunnel. The 3-dimensional inlet was designed to have the combustor inlet flow nearly two-dimensional and of sufficient mass flow necessary for combustion. The 16-inch shock tunnel experiment is a short duration test with test time of the order of milliseconds. The flow through the inlet is in chemical non-equilibrium. Two test entries have been completed and limited experimental results for the inlet region of the combustor-model are available. A number of CFD simulations, with various levels of simplifications such as 2-D simulations, 3-D simulations with and without chemical reactions, simulations with and without turbulent conditions, etc., have been performed. These simulations have helped determine the model inlet flow characteristics and the important factors that affect the combustor inlet flow and the sensitivity of the flow field to these simplifications. In the proposed paper, CFD modeling of the hypersonic inlet, results from the simulations and comparison with available experimental results will be presented.

Transition Experiments on Large Bluntness Cones with Distributed Roughness in Hypersonic Flight

Science.gov (United States)

Reda, Daniel. C.; Wilder, Michael C.; Prabhu, Dinesh K.

2012-01-01

Large bluntness cones with smooth nosetips and roughened frusta were flown in the NASA Ames hypersonic ballistic range at a Mach number of 10 through quiescent air environments. Global surface intensity (temperature) distributions were optically measured and analyzed to determine transition onset and progression over the roughened surface. Real-gas Navier-Stokes calculations of model flowfields, including laminar boundary layer development in these flowfields, were conducted to predict values of key dimensionless parameters used to correlate transition on such configurations in hypersonic flow. For these large bluntness cases, predicted axial distributions of the roughness Reynolds number showed (for each specified freestream pressure) that this parameter was a maximum at the physical beginning of the roughened zone and decreased with increasing run length along the roughened surface. Roughness-induced transition occurred downstream of this maximum roughness Reynolds number location, and progressed upstream towards the beginning of the roughened zone as freestream pressure was systematically increased. Roughness elements encountered at the upstream edge of the roughened frusta thus acted like a finite-extent trip array, consistent with published results concerning the tripping effectiveness of roughness bands placed on otherwise smooth surfaces.

Unsteady Heat-Flux Measurements of Second-Mode Instability Waves in a Hypersonic Boundary Layer

Science.gov (United States)

Kergerise, Michael A.; Rufer, Shann J.

2016-01-01

In this paper we report on the application of the atomic layer thermopile (ALTP) heat- flux sensor to the measurement of laminar-to-turbulent transition in a hypersonic flat plate boundary layer. The centerline of the flat-plate model was instrumented with a streamwise array of ALTP sensors and the flat-plate model was exposed to a Mach 6 freestream over a range of unit Reynolds numbers. Here, we observed an unstable band of frequencies that are associated with second-mode instability waves in the laminar boundary layer that forms on the flat-plate surface. The measured frequencies, group velocities, phase speeds, and wavelengths of these instability waves are in agreement with data previously reported in the literature. Heat flux time series, and the Morlet-wavelet transforms of them, revealed the wave-packet nature of the second-mode instability waves. In addition, a laser-based radiative heating system was developed to measure the frequency response functions (FRF) of the ALTP sensors used in the wind tunnel test. These measurements were used to assess the stability of the sensor FRFs over time and to correct spectral estimates for any attenuation caused by the finite sensor bandwidth.

Impact of state-specific flowfield modeling on atomic nitrogen radiation

Science.gov (United States)

Johnston, Christopher O.; Panesi, Marco

2018-01-01

A hypersonic flowfield model that treats electronic levels of the dominant afterbody radiator N as individual species is presented. This model allows electron-ion recombination rate and two-temperature modeling improvements, the latter which are shown to decrease afterbody radiative heating by up to 30%. This decrease is primarily due to the addition of the electron-impact excitation energy-exchange term to the energy equation governing the vibrational-electronic electron temperature. This model also allows the validity of the often applied quasi-steady-state (QSS) approximation to be assessed. The QSS approximation is shown to fail throughout most of the afterbody region for lower electronic states, although this impacts the radiative intensity reaching the surface by less than 15%. By computing the electronic-state populations of N within the flowfield solver, instead of through the QSS approximation in the radiation solver, the coupling of nonlocal radiative transition rates to the species continuity equations becomes feasible. Implementation of this higher-fidelity level of coupling between the flowfield and radiation solvers is shown to increase the afterbody radiation by up to 50% relative to the conventional model.

Shock Tunnel Studies of the Hypersonic Flowfield around the Hypervelocity Ballistic Models with Aerospikes

Science.gov (United States)

Balakalyani, G.; Saravanan, S.; Jagadeesh, G.

Reduced drag and aerodynamic heating are the two basic design requirements for any hypersonic vehicle [1]. The flowfield around an axisymmetric blunt body is characterized by a bow shockwave standing ahead of its nose. The pressure and temperature behind this shock wave are very high. This increased pressure and temperature are responsible for the high levels of drag and aerodynamic heating over the body. In the past, there have been many investigations on the use of aerospikes as a drag reduction tool. These studies on spiked bodies aim at reducing both the drag and aerodynamic heating by modifying the hypersonic flowfield ahead of the nose of the body [2]. However, most of them used very simple configurations to experimentally study the drag reduction using spikes at hypersonic speeds [3] and therefore very little experimental data is available for a realistic geometric configuration. In the present study, the standard AGARD Hypervelocity Ballistic model 1 is used as the test model. The addition of the spike to the blunt body significantly alters the flowfield ahead of the nose, leading to the formation of a low pressure conical recirculation region, thus causing a reduction in drag and wall heat flux [4]. In the present investigation, aerodynamic drag force is measured over the Hypervelocity Ballistic model-1, with and without spike, at a flow enthalpy of 1.7 MJ/kg. The experiments are carried out at a Mach number of 8 and at zero angle of attack. An internally mountable accelerometer based 3-component force balance system is used to measure the aerodynamic forces on the model. Also computational studies are carried out to complement the experiments.

Trajectory Optimization and Conceptual Study of Small Test Vehicles for a Hypersonic Engine Using a High-Altitude Balloon

Science.gov (United States)

Tsuchiya, Takeshi; Takenaka, Youichi; Taguchi, Hideyuki; Sawai, Shujiro

The Japan Aerospace Exploration Agency, JAXA, announced a long-term vision recently. In the vision, JAXA aims to develop hypersonic aircrafts. A pre-cooled turbojet engine has great potential as one of newly developed hypersonic airbreathing engines. We also expect the engine to be installed in space transportation vehicles in the future. For combustion test in the real flight conditions of the engines, JAXA has an experimental plan where a small test vehicle is released from a high-altitude balloon. This paper applies numerical analysis and optimization techniques to conceptual designs of the test vehicle in order to obtain the best configuration and trajectory for the flight test. The results show helpful knowledge for designing prototype vehicles.

Characterization of diagnostic hole-closure in Z-pinch driven hohlraums

International Nuclear Information System (INIS)

Baker, K. L.; Porter, J. L.; Ruggles, L. E.; Chandler, G. A.; Deeney, Chris; Vargas, M.; Moats, Ann; Struve, Ken; Torres, J.; McGurn, J. S.

2000-01-01

In this article we investigate the partial closure of diagnostic holes in Z-pinch driven hohlraums. These hohlraums differ from current laser-driven hohlraums in a number of ways such as their larger size, greater x-ray drive energy, and lower temperature. Although the diameter of the diagnostic holes on these Z-pinch driven hohlraums can be much greater than their laser-driven counterparts, 4 mm in diameter or larger, radiation impinges on the wall material surrounding the hole for the duration of the Z pinch, nearly 100 ns. This incident radiation causes plasma to ablate from the hohlraum walls surrounding the diagnostic hole and partially obscure this diagnostic hole. This partial obscuration reduces the effective area over which diagnostics view the hohlraum's radiation. This reduction in area can lead to an underestimation of the wall temperature when nonimaging diagnostics such as x-ray diodes and bolometers are used to determine power and later to infer a wall temperature. In this article we describe the techniques used to characterize the hole-closure in these hohlraums and present the experimental measurements of this process. (c) 2000 American Institute of Physics

Characterization of diagnostic hole-closure in Z-pinch driven hohlraums

Energy Technology Data Exchange (ETDEWEB)

Baker, K. L. [Sandia National Laboratory, Albuquerque, New Mexico 87185 (United States); Porter, J. L. [Sandia National Laboratory, Albuquerque, New Mexico 87185 (United States); Ruggles, L. E. [Sandia National Laboratory, Albuquerque, New Mexico 87185 (United States); Chandler, G. A. [Sandia National Laboratory, Albuquerque, New Mexico 87185 (United States); Deeney, Chris [Sandia National Laboratory, Albuquerque, New Mexico 87185 (United States); Vargas, M. [Sandia National Laboratory, Albuquerque, New Mexico 87185 (United States); Moats, Ann [Sandia National Laboratory, Albuquerque, New Mexico 87185 (United States); Struve, Ken [Sandia National Laboratory, Albuquerque, New Mexico 87185 (United States); Torres, J. [Sandia National Laboratory, Albuquerque, New Mexico 87185 (United States); McGurn, J. S. [Sandia National Laboratory, Albuquerque, New Mexico 87185 (United States)] (and others)

2000-02-01

In this article we investigate the partial closure of diagnostic holes in Z-pinch driven hohlraums. These hohlraums differ from current laser-driven hohlraums in a number of ways such as their larger size, greater x-ray drive energy, and lower temperature. Although the diameter of the diagnostic holes on these Z-pinch driven hohlraums can be much greater than their laser-driven counterparts, 4 mm in diameter or larger, radiation impinges on the wall material surrounding the hole for the duration of the Z pinch, nearly 100 ns. This incident radiation causes plasma to ablate from the hohlraum walls surrounding the diagnostic hole and partially obscure this diagnostic hole. This partial obscuration reduces the effective area over which diagnostics view the hohlraum's radiation. This reduction in area can lead to an underestimation of the wall temperature when nonimaging diagnostics such as x-ray diodes and bolometers are used to determine power and later to infer a wall temperature. In this article we describe the techniques used to characterize the hole-closure in these hohlraums and present the experimental measurements of this process. (c) 2000 American Institute of Physics.

Design, Validation, and Testing of a Hot-Film Anemometer for Hypersonic Flow

Science.gov (United States)

Sheplak, Mark

The application of constant-temperature hot-film anemometry to hypersonic flow has been reviewed and extended in this thesis. The objective of this investigation was to develop a measurement tool capable of yielding continuous, high-bandwidth, quantitative, normal mass-flux and total -temperature measurements in moderate-enthalpy environments. This research has produced a probe design that represents a significant advancement over existing designs, offering the following improvements: (1) a five-fold increase in bandwidth; (2) true stagnation-line sensor placement; (3) a two order-of-magnitude decrease in sensor volume; and (4) over a 70% increase in maximum film temperature. These improvements were achieved through substrate design, sensor placement, the use of high-temperature materials, and state -of-the-art microphotolithographic fabrication techniques. The experimental study to characterize the probe was performed in four different hypersonic wind tunnels at NASA-Langley Research Center. The initial test consisted of traversing the hot film through a Mach 6, flat-plate, turbulent boundary layer in air. The detailed static-calibration measurements that followed were performed in two different hypersonic flows: a Mach 11 helium flow and Mach 6 air flow. The final test of this thesis consisted of traversing the probe through the Mach 6 wake of a 70^ circ blunt body. The goal of this test was to determine the state (i.e., laminar or turbulent) of the wake. These studies indicate that substrate conduction effects result in instrumentation characteristics that prevent the hot-film anemometer from being used as a quantitative tool. The extension of this technique to providing quantitative information is dependent upon the development of lower thermal-conductivity substrate materials. However, the probe durability, absence of strain gauging, and high bandwidth represent significant improvements over the hot-wire technique for making qualitative measurements. Potential

Laser-driven wakefield electron acceleration and associated radiation sources

International Nuclear Information System (INIS)

Davoine, X.

2009-10-01

The first part of this research thesis introduces the basic concepts needed for the understanding of the laser-driven wakefield acceleration. It describes the properties of the used laser beams and plasmas, presents some notions about laser-plasma interactions for a better understanding of the physics of laser-driven acceleration. The second part deals with the numerical modelling and the presentation of simulation tools needed for the investigation of laser-induced wakefield acceleration. The last part deals with the optical control of the injection, a technique analogous to the impulsion collision scheme

Radiation loss driven instabilities in laser heated plasmas

International Nuclear Information System (INIS)

Evans, R.G.

1985-01-01

Any plasma in which a significant part of the power balance is due to optically thin radiative losses may be subject to a radiation cooling instability. A simple analytical model gives the dispersion relation for the instability and inclusion of a realistic radiation loss term in a two dimensional hydrodynamic simulation shows that ''jet'' like features form in moderate to high Z plasmas

Robust Adaptive Flight Control Design of Air-breathing Hypersonic Vehicles

Science.gov (United States)

2016-12-07

advantages over rocket - based systems for space access vehicles. The major advantage of using air-breathing engine is that the extra oxidizer is not...sideslip angle (β) is calculated as Vt = p u2 + v2 +w2, α= t an−1 ( wu ), β= si n−1 ( vVt ) The rotational dynamic equations of AHV are given as Ṗ = c1QR...inverse controller for hypersonic vehicle. In 2010 International Conference on Information, Networking and Automation (ICINA), volume 2, pages V2 –240

Theoretical investigation of non-equilibrium chemistry and optical radiation in hypersonic flow fields

Science.gov (United States)

Whiting, Ellis E.

1990-01-01

Future space vehicles returning from distant missions or high earth orbits may enter the upper regions of the atmosphere and use aerodynamic drag to reduce their velocity before they skip out of the atmosphere and enter low earth orbit. The Aeroassist Flight Experiment (AFE) is designed to explore the special problems encountered in such entries. A computer code was developed to calculate the radiative transport along line-or-sight in the general 3-D flow field about an arbitrary entry vehicle, if the temperatures and species concentrations along the line-of-sight are known. The radiative heating calculation at the stagnation point of the AFE vehicle along the entry trajectory was performed, including a detailed line-by-line accounting of the radiative transport in the vacuum ultraviolet (below 200 nm) by the atomic N and O lines. A method was developed for making measurements of the haze particles in the Titan atmosphere above 200 km altitude. Several other tasks of a continuing nature, to improve the technical ability to calculate the nonequilibrium gas dynamic flow field and radiative heating of entry vehicles, were completed or advanced.

Nonlinear evolution of Mack modes in a hypersonic boundary layer

Science.gov (United States)

Chokani, Ndaona

2005-01-01

In hypersonic boundary layer flows the nonlinear disturbance evolution occurs relatively slowly over a very long length scale and has a profound effect on boundary layer transition. In the case of low-level freestream disturbances and negligible surface roughness, the transition is due to the modal growth of exponentially growing Mack modes that are destabilized by wall cooling. Cross-bicoherence measurements, derived from hot-wire data acquired in a quiet hypersonic tunnel, are used to identify and quantify phase-locked, quadratic sum and difference interactions involving the Mack modes. In the early stages of the nonlinear disturbance evolution, cross-bicoherence measurements indicate that the energy exchange between the Mack mode and the mean flow first occurs to broaden the sidebands; this is immediately followed by a sum interaction of the Mack mode to generate the first harmonic. In the next stages of the nonlinear disturbance evolution, there is a difference interaction of the first harmonic, which is also thought to contribute to the mean flow distortion. This difference interaction, in the latter stages, is also accompanied by a difference interaction between Mack mode and first harmonic, and a sum interaction, which forces the second harmonic. Analysis using the digital complex demodulation technique, shows that the low-frequency, phase-locked interaction that is identified in the cross bicoherence when the Mack mode and first harmonic have large amplitudes, arises due to the amplitude modulation of Mack mode and first harmonic.

Prediction of forces and moments for flight vehicle control effectors. Part 1: Validation of methods for predicting hypersonic vehicle controls forces and moments

Science.gov (United States)

Maughmer, Mark D.; Ozoroski, L.; Ozoroski, T.; Straussfogel, D.

1990-01-01

Many types of hypersonic aircraft configurations are currently being studied for feasibility of future development. Since the control of the hypersonic configurations throughout the speed range has a major impact on acceptable designs, it must be considered in the conceptual design stage. The ability of the aerodynamic analysis methods contained in an industry standard conceptual design system, APAS II, to estimate the forces and moments generated through control surface deflections from low subsonic to high hypersonic speeds is considered. Predicted control forces and moments generated by various control effectors are compared with previously published wind tunnel and flight test data for three configurations: the North American X-15, the Space Shuttle Orbiter, and a hypersonic research airplane concept. Qualitative summaries of the results are given for each longitudinal force and moment and each control derivative in the various speed ranges. Results show that all predictions of longitudinal stability and control derivatives are acceptable for use at the conceptual design stage. Results for most lateral/directional control derivatives are acceptable for conceptual design purposes; however, predictions at supersonic Mach numbers for the change in yawing moment due to aileron deflection and the change in rolling moment due to rudder deflection are found to be unacceptable. Including shielding effects in the analysis is shown to have little effect on lift and pitching moment predictions while improving drag predictions.

Numerical study on aerodynamic heat of hypersonic flight

Directory of Open Access Journals (Sweden)

Huang Haiming

2016-01-01

Full Text Available Accurate prediction of the shock wave has a significant effect on the development of space transportation vehicle or exploration missions. Taking Lobb sphere as the example, the aerodynamic heat of hypersonic flight in different Mach numbers is simulated by the finite volume method. Chemical reactions and non-equilibrium heat are taken into account in this paper, where convective flux of the space term adopts the Roe format, and discretization of the time term is achieved by backward Euler algorithm. The numerical results reveal that thick mesh can lead to accurate prediction, and the thickness of the shock wave decreases as grid number increases. Furthermore, most of kinetic energy converts into internal energy crossing the shock wave.

Radiation-pressure-driven sub-Keplerian rotation of the disc around the AGB star L2 Pup

Science.gov (United States)

Haworth, Thomas J.; Booth, Richard A.; Homan, Ward; Decin, Leen; Clarke, Cathie J.; Mohanty, Subhanjoy

2018-01-01

We study the sub-Keplerian rotation and dust content of the circumstellar material around the asymptotic giant branch (AGB) star L2 Puppis. We find that the thermal pressure gradient alone cannot explain the observed rotation profile. We find that there is a family of possible dust populations for which radiation pressure can drive the observed sub-Keplerian rotation. This set of solutions is further constrained by the spectral energy distribution (SED) of the system, and we find that a dust-to-gas mass ratio of ∼10-3 and a maximum grain size that decreases radially outwards can satisfy both the rotation curve and SED. These dust populations are dynamically tightly coupled to the gas azimuthally. However, grains larger than ∼ 0.5 μm are driven outwards radially by radiation pressure at velocities ∼5 km s-1, which implies a dust replenishment rate of ∼3 × 10-9 M⊙ yr-1. This replenishment rate is consistent with observational estimates to within uncertainties. Coupling between the radial motion of the dust and gas is weak and hence the gas does not share in this rapid outward motion. Overall, we conclude that radiation pressure is a capable and necessary mechanism to explain the observed rotation profile of L2 Pup, and offers other additional constraints on the dust properties.

CAN-DO, CFD-based Aerodynamic Nozzle Design and Optimization program for supersonic/hypersonic wind tunnels

Science.gov (United States)

Korte, John J.; Kumar, Ajay; Singh, D. J.; White, J. A.

1992-01-01

A design program is developed which incorporates a modern approach to the design of supersonic/hypersonic wind-tunnel nozzles. The approach is obtained by the coupling of computational fluid dynamics (CFD) with design optimization. The program can be used to design a 2D or axisymmetric, supersonic or hypersonic, wind-tunnel nozzles that can be modeled with a calorically perfect gas. The nozzle design is obtained by solving a nonlinear least-squares optimization problem (LSOP). The LSOP is solved using an iterative procedure which requires intermediate flowfield solutions. The nozzle flowfield is simulated by solving the Navier-Stokes equations for the subsonic and transonic flow regions and the parabolized Navier-Stokes equations for the supersonic flow regions. The advantages of this method are that the design is based on the solution of the viscous equations eliminating the need to make separate corrections to a design contour, and the flexibility of applying the procedure to different types of nozzle design problems.

Nonequilibrium radiation behind a strong shock wave in CO 2-N 2

Science.gov (United States)

Rond, C.; Boubert, P.; Félio, J.-M.; Chikhaoui, A.

2007-11-01

This work presents experiments reproducing plasma re-entry for one trajectory point of a Martian mission. The typical facility to investigate such hypersonic flow is shock tube; here we used the free-piston shock tube TCM2. Measurements of radiative flux behind the shock wave are realized thanks to time-resolved emission spectroscopy which is calibrated in intensity. As CN violet system is the main radiator in near UV-visible range, we have focused our study on its spectrum. Moreover a physical model, based on a multi-temperature kinetic code and a radiative code, for calculation of non equilibrium radiation behind a shock wave is developed for CO 2-N 2-Ar mixtures. Comparisons between experiments and calculations show that standard kinetic models (Park, McKenzie) are inefficient to reproduce our experimental results. Therefore we propose new rate coefficients in particular for the dissociation of CO 2, showing the way towards a better description of the chemistry of the mixture.

Combustion Efficiency, Flameout Operability Limits and General Design Optimization for Integrated Ramjet-Scramjet Hypersonic Vehicles

Science.gov (United States)

Mbagwu, Chukwuka Chijindu

High speed, air-breathing hypersonic vehicles encounter a varied range of engine and operating conditions traveling along cruise/ascent missions at high altitudes and dynamic pressures. Variations of ambient pressure, temperature, Mach number, and dynamic pressure can affect the combustion conditions in conflicting ways. Computations were performed to understand propulsion tradeoffs that occur when a hypersonic vehicle travels along an ascent trajectory. Proper Orthogonal Decomposition methods were applied for the reduction of flamelet chemistry data in an improved combustor model. Two operability limits are set by requirements that combustion efficiency exceed selected minima and flameout be avoided. A method for flameout prediction based on empirical Damkohler number measurements is presented. Operability limits are plotted that define allowable flight corridors on an altitude versus flight Mach number performance map; fixed-acceleration ascent trajectories were considered for this study. Several design rules are also presented for a hypersonic waverider with a dual-mode scramjet engine. Focus is placed on ''vehicle integration" design, differing from previous ''propulsion-oriented" design optimization. The well-designed waverider falls between that of an aircraft (high lift-to-drag ratio) and a rocket (high thrust-to-drag ratio). 84 variations of an X-43-like vehicle were run using the MASIV scramjet reduced order model to examine performance tradeoffs. Informed by the vehicle design study, variable-acceleration trajectory optimization was performed for three constant dynamic pressures ascents. Computed flameout operability limits were implemented as additional constraints to the optimization problem. The Michigan-AFRL Scramjet In-Vehicle (MASIV) waverider model includes finite-rate chemistry, applied scaling laws for 3-D turbulent mixing, ram-scram transition and an empirical value of the flameout Damkohler number. A reduced-order modeling approach is justified

An experimental setup for visualizations and measurements on free hypersonic jets

Directory of Open Access Journals (Sweden)

Tordella Daniela

2012-04-01

Full Text Available The free hypersonic jets can be found in several technological applications and even in astrophysical observations. This article is mainly devoted to explain an experiment about visualizations and measurements on free hypersonic jets extending on length scales in the order of hundreds of initial diameters and traveling in a medium not necessarily made of the same gas of the jets. The experiments are performed by means of special facilities where the jet Mach numbers and the jetto-ambient density ratios can be set independently of each other, what permits the investigation of a wide parameters range in the relevant physics. The Mach number of the jets ranges from 5 to 20 and the jet-to ambient density ratio, which plays an important role in the jets morphology, can be set from 0.1 up to values exceeding 100. The present setup produces the jets by means of a fast piston system (for high Mach numbers or injection valves (for low Mach numbers, both coupled with de Laval nozzles. The visualizations and measurements are based on the electron beam technique: the jets are weakly ionized, then a fast CMOS camera captures images that are analyzed by image processing techniques. A sample of the results obtained by this experimental system is included at the end of this work.

Boundary layer-shock interaction in hypersonic flows with chemical reaction effects

International Nuclear Information System (INIS)

Mirzaei, M.; Shadaram, A.; Jahantigh, N.

2003-01-01

In this paper, viscous interaction phenomenon in hypersonic flows with chemical reactions is numerically simulated. Two-dimensional Navier-Stokes equations are solved to simulate this phenomenon. Inviscid fluxes are approximated using Van Leer flux vector splitting method and to increase the accuracy of this approximation, MUSCL approach with Van albada limiters is applied. Chemical reactions are considered to be in equilibrium conditions. With this assumption there is no closed form for equation of state for the gas (air) and relation between thermodynamic properties are calculated from thermodynamic tables. In addition, transport properties (viscosity and conductivity) are functions of two independent thermodynamic properties. These functions are calculated using kinetic theory. To evaluate the performance of the model used in this research, some test cases are studied. First test case is flow over a ramp with various angles. The results of this test case are compared with the results of other numerical methods and the effect of geometry on separation length is studied. The second case is a hypersonic flow over a 15-degree ramp. The results are in good agreement compared with experimental data. In addition, there results are compared with the results of ideal gas (non-reacting flow) calculations. It can be seen that ideal gas assumption for air introduces considerable deviation form experimental data. (author)

Transition Prediction in Hypersonic Boundary Layers Using Receptivity and Freestream Spectra

Science.gov (United States)

Balakumar, P.; Chou, Amanda

2016-01-01

Boundary-layer transition in hypersonic flows over a straight cone can be predicted using measured freestream spectra, receptivity, and threshold values for the wall pressure fluctuations at the transition onset points. Simulations are performed for hypersonic boundary-layer flows over a 7-degree half-angle straight cone with varying bluntness at a freestream Mach number of 10. The steady and the unsteady flow fields are obtained by solving the two-dimensional Navier-Stokes equations in axisymmetric coordinates using a 5th-order accurate weighted essentially non-oscillatory (WENO) scheme for space discretization and using a third-order total-variation-diminishing (TVD) Runge-Kutta scheme for time integration. The calculated N-factors at the transition onset location increase gradually with increasing unit Reynolds numbers for flow over a sharp cone and remain almost the same for flow over a blunt cone. The receptivity coefficient increases slightly with increasing unit Reynolds numbers. They are on the order of 4 for a sharp cone and are on the order of 1 for a blunt cone. The location of transition onset predicted from the simulation including the freestream spectrum, receptivity, and the linear and the weakly nonlinear evolutions yields a solution close to the measured onset location for the sharp cone. The simulations over-predict transition onset by about twenty percent for the blunt cone.

Flight Experiments for Hypersonic Vehicle Development (Experimentations envol pour le developpement d'un vehicule hypersonique) (CD-ROM)

National Research Council Canada - National Science Library

2007-01-01

...: 1 CD-ROM; 4 3/4 in.; 124 MB. ABSTRACT: This RTO-AVT/VKI Lecture Series brought together specialists from Europe, USA, and Russia to discuss flight experiments that pertain to the development of hypersonic vehicles...

Tracking error constrained robust adaptive neural prescribed performance control for flexible hypersonic flight vehicle

Directory of Open Access Journals (Sweden)

Zhonghua Wu

2017-02-01

Full Text Available A robust adaptive neural control scheme based on a back-stepping technique is developed for the longitudinal dynamics of a flexible hypersonic flight vehicle, which is able to ensure the state tracking error being confined in the prescribed bounds, in spite of the existing model uncertainties and actuator constraints. Minimal learning parameter technique–based neural networks are used to estimate the model uncertainties; thus, the amount of online updated parameters is largely lessened, and the prior information of the aerodynamic parameters is dispensable. With the utilization of an assistant compensation system, the problem of actuator constraint is overcome. By combining the prescribed performance function and sliding mode differentiator into the neural back-stepping control design procedure, a composite state tracking error constrained adaptive neural control approach is presented, and a new type of adaptive law is constructed. As compared with other adaptive neural control designs for hypersonic flight vehicle, the proposed composite control scheme exhibits not only low-computation property but also strong robustness. Finally, two comparative simulations are performed to demonstrate the robustness of this neural prescribed performance controller.

Picosecond phase-velocity dispersion of hypersonic phonons imaged with ultrafast electron microscopy

International Nuclear Information System (INIS)

Cremons, Daniel R.; Du, Daniel X.; Flannigan, David J.

2017-01-01

We describe the direct imaging—with four-dimensional ultrafast electron microscopy—of the emergence, evolution, dispersion, and decay of photoexcited, hypersonic coherent acoustic phonons in nanoscale germanium wedges. Coherent strain waves generated via ultrafast in situ photoexcitation were imaged propagating with initial phase velocities of up to 35 km/s across discrete micrometer-scale crystal regions. We then observe that, while each wave front travels at a constant velocity, the entire wave train evolves with a time-varying phase-velocity dispersion, displaying a single-exponential decay to the longitudinal speed of sound (5 km/s) and with a mean lifetime of 280 ps. We also find that the wave trains propagate along a single in-plane direction oriented parallel to striations introduced during specimen preparation, independent of crystallographic direction. Elastic-plate modeling indicates the dynamics arise from excitation of a single, symmetric (dilatational) guided acoustic mode. Further, by precisely determining the experiment time-zero position with a plasma-lensing method, we find that wave-front emergence occurs approximately 100 ps after femtosecond photoexcitation, which matches well with Auger recombination times in germanium. We conclude by discussing the similarities between the imaged hypersonic strain-wave dynamics and electron/hole plasma-wave dynamics in strongly photoexcited semiconductors.

Picosecond phase-velocity dispersion of hypersonic phonons imaged with ultrafast electron microscopy

Science.gov (United States)

Cremons, Daniel R.; Du, Daniel X.; Flannigan, David J.

2017-12-01

Here, we describe the direct imaging—with four-dimensional ultrafast electron microscopy—of the emergence, evolution, dispersion, and decay of photoexcited, hypersonic coherent acoustic phonons in nanoscale germanium wedges. Coherent strain waves generated via ultrafast in situ photoexcitation were imaged propagating with initial phase velocities of up to 35 km/s across discrete micrometer-scale crystal regions. We observe that, while each wave front travels at a constant velocity, the entire wave train evolves with a time-varying phase-velocity dispersion, displaying a single-exponential decay to the longitudinal speed of sound (5 km/s) and with a mean lifetime of 280 ps. We also find that the wave trains propagate along a single in-plane direction oriented parallel to striations introduced during specimen preparation, independent of crystallographic direction. Elastic-plate modeling indicates the dynamics arise from excitation of a single, symmetric (dilatational) guided acoustic mode. Further, by precisely determining the experiment time-zero position with a plasma-lensing method, we find that wave-front emergence occurs approximately 100 ps after femtosecond photoexcitation, which matches well with Auger recombination times in germanium. We conclude by discussing the similarities between the imaged hypersonic strain-wave dynamics and electron/hole plasma-wave dynamics in strongly photoexcited semiconductors.

RADIATIVE RAYLEIGH-TAYLOR INSTABILITIES

International Nuclear Information System (INIS)

Jacquet, Emmanuel; Krumholz, Mark R.

2011-01-01

We perform analytic linear stability analyses of an interface separating two stratified media threaded by a radiation flux, a configuration relevant in several astrophysical contexts. We develop a general framework for analyzing such systems and obtain exact stability conditions in several limiting cases. In the optically thin, isothermal regime, where the discontinuity is chemical in nature (e.g., at the boundary of a radiation pressure-driven H II region), radiation acts as part of an effective gravitational field, and instability arises if the effective gravity per unit volume toward the interface overcomes that away from it. In the optically thick a diabaticregime where the total (gas plus radiation) specific entropy of a Lagrangian fluid element is conserved, for example at the edge of radiation pressure-driven bubble around a young massive star, we show that radiation acts like a modified equation of state and derive a generalized version of the classical Rayleigh-Taylor stability condition.

Development of a Z-pinch-driven ICF hohlraum concept on Z

International Nuclear Information System (INIS)

Cuneo, M.E.; Porter, J.L. Jr.; Vesey, R.A.

1999-01-01

Recent development of high power z-pinches (> 150 MW) on the Z driver has permitted the study of high-temperature, radiation-driven hohlraums. Three complementary, Z-pinch source-hohlraum-ICF capsule configurations are being developed to harness the x-ray output of these Z-pinch's. These are the dynamic-hohlraum, static-wall hohlraum, and Z-pinch-driven hohlraum concepts. Each has different potential strengths and concerns. In this paper, the authors report on the first experiments with the Z-pinch-driven hohlraum (ZPDH) concept. A high-yield ICF capsule design for this concept appears feasible, when driven by z-pinches from a 60 MA-class driver. Initial experiments characterize the behavior of the spoke array on Z-pinch performance and x-ray transmission, and the uniformity of radiation flux incident on a foam capsule in the secondary, for a single-sided drive. Measurements of x-ray wall re-emission power and spectrum, radiation temperatures, spoke-plasma location, and drive uniformity will be presented and compared with 0-D energetics, 2-D Lasnex rad-hydro, and 3-D radiosity calculations of energy transport and drive uniformity

Development of a Z-pinch-driven ICF hohlraum concept on Z

Energy Technology Data Exchange (ETDEWEB)

Cuneo, M E; Porter, Jr, J L; Vesey, R A [and others

1999-07-01

Recent development of high power z-pinches (> 150 MW) on the Z driver has permitted the study of high-temperature, radiation-driven hohlraums. Three complementary, Z-pinch source-hohlraum-ICF capsule configurations are being developed to harness the x-ray output of these Z-pinch's. These are the dynamic-hohlraum, static-wall hohlraum, and Z-pinch-driven hohlraum concepts. Each has different potential strengths and concerns. In this paper, the authors report on the first experiments with the Z-pinch-driven hohlraum (ZPDH) concept. A high-yield ICF capsule design for this concept appears feasible, when driven by z-pinches from a 60 MA-class driver. Initial experiments characterize the behavior of the spoke array on Z-pinch performance and x-ray transmission, and the uniformity of radiation flux incident on a foam capsule in the secondary, for a single-sided drive. Measurements of x-ray wall re-emission power and spectrum, radiation temperatures, spoke-plasma location, and drive uniformity will be presented and compared with 0-D energetics, 2-D Lasnex rad-hydro, and 3-D radiosity calculations of energy transport and drive uniformity.

Observable Signatures of Wind-driven Chemistry with a Fully Consistent Three-dimensional Radiative Hydrodynamics Model of HD 209458b

Science.gov (United States)

Drummond, B.; Mayne, N. J.; Manners, J.; Carter, A. L.; Boutle, I. A.; Baraffe, I.; Hébrard, É.; Tremblin, P.; Sing, D. K.; Amundsen, D. S.; Acreman, D.

2018-03-01

We present a study of the effect of wind-driven advection on the chemical composition of hot-Jupiter atmospheres using a fully consistent 3D hydrodynamics, chemistry, and radiative transfer code, the Met Office Unified Model (UM). Chemical modeling of exoplanet atmospheres has primarily been restricted to 1D models that cannot account for 3D dynamical processes. In this work, we couple a chemical relaxation scheme to the UM to account for the chemical interconversion of methane and carbon monoxide. This is done consistently with the radiative transfer meaning that departures from chemical equilibrium are included in the heating rates (and emission) and hence complete the feedback between the dynamics, thermal structure, and chemical composition. In this Letter, we simulate the well studied atmosphere of HD 209458b. We find that the combined effect of horizontal and vertical advection leads to an increase in the methane abundance by several orders of magnitude, which is directly opposite to the trend found in previous works. Our results demonstrate the need to include 3D effects when considering the chemistry of hot-Jupiter atmospheres. We calculate transmission and emission spectra, as well as the emission phase curve, from our simulations. We conclude that gas-phase nonequilibrium chemistry is unlikely to explain the model–observation discrepancy in the 4.5 μm Spitzer/IRAC channel. However, we highlight other spectral regions, observable with the James Webb Space Telescope, where signatures of wind-driven chemistry are more prominant.

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.

A method for the direct numerical simulation of hypersonic boundary-layer instability with finite-rate chemistry

International Nuclear Information System (INIS)

Marxen, Olaf; Magin, Thierry E.; Shaqfeh, Eric S.G.; Iaccarino, Gianluca

2013-01-01

A new numerical method is presented here that allows to consider chemically reacting gases during the direct numerical simulation of a hypersonic fluid flow. The method comprises the direct coupling of a solver for the fluid mechanical model and a library providing the physio-chemical model. The numerical method for the fluid mechanical model integrates the compressible Navier–Stokes equations using an explicit time advancement scheme and high-order finite differences. This Navier–Stokes code can be applied to the investigation of laminar-turbulent transition and boundary-layer instability. The numerical method for the physio-chemical model provides thermodynamic and transport properties for different gases as well as chemical production rates, while here we exclusively consider a five species air mixture. The new method is verified for a number of test cases at Mach 10, including the one-dimensional high-temperature flow downstream of a normal shock, a hypersonic chemical reacting boundary layer in local thermodynamic equilibrium and a hypersonic reacting boundary layer with finite-rate chemistry. We are able to confirm that the diffusion flux plays an important role for a high-temperature boundary layer in local thermodynamic equilibrium. Moreover, we demonstrate that the flow for a case previously considered as a benchmark for the investigation of non-equilibrium chemistry can be regarded as frozen. Finally, the new method is applied to investigate the effect of finite-rate chemistry on boundary layer instability by considering the downstream evolution of a small-amplitude wave and comparing results with those obtained for a frozen gas as well as a gas in local thermodynamic equilibrium

High-order non-uniform grid schemes for numerical simulation of hypersonic boundary-layer stability and transition

International Nuclear Information System (INIS)

Zhong Xiaolin; Tatineni, Mahidhar

2003-01-01

The direct numerical simulation of receptivity, instability and transition of hypersonic boundary layers requires high-order accurate schemes because lower-order schemes do not have an adequate accuracy level to compute the large range of time and length scales in such flow fields. The main limiting factor in the application of high-order schemes to practical boundary-layer flow problems is the numerical instability of high-order boundary closure schemes on the wall. This paper presents a family of high-order non-uniform grid finite difference schemes with stable boundary closures for the direct numerical simulation of hypersonic boundary-layer transition. By using an appropriate grid stretching, and clustering grid points near the boundary, high-order schemes with stable boundary closures can be obtained. The order of the schemes ranges from first-order at the lowest, to the global spectral collocation method at the highest. The accuracy and stability of the new high-order numerical schemes is tested by numerical simulations of the linear wave equation and two-dimensional incompressible flat plate boundary layer flows. The high-order non-uniform-grid schemes (up to the 11th-order) are subsequently applied for the simulation of the receptivity of a hypersonic boundary layer to free stream disturbances over a blunt leading edge. The steady and unsteady results show that the new high-order schemes are stable and are able to produce high accuracy for computations of the nonlinear two-dimensional Navier-Stokes equations for the wall bounded supersonic flow

Assessment of CFD Capability for Hypersonic Shock Wave Laminar Boundary Layer Interactions

OpenAIRE

Mehrnaz Rouhi Youssefi; Doyle Knight

2017-01-01

The goal of this study is to assess CFD capability for the prediction of shock wave laminar boundary layer interactions at hypersonic velocities. More specifically, the flow field over a double-cone configuration is simulated using both perfect gas and non-equilibrium Navier–Stokes models. Computations are compared with recent experimental data obtained from measurements conducted in the LENS XX (Large Energy National Shock Expansion Tunnel Version 2) at the Calspan University of Buffalo Rese...

Design, Performance, and Operation of Efficient Ramjet/Scramjet Combined Cycle Hypersonic Propulsion

Science.gov (United States)

2009-10-16

simulations, the blending of the RANS and LES portions is handled by the standard DES equations, now referred to as DES97. The one-equation Spalart...think that RANS can capture these dynamics. • Much remains to be learned about how to model chemistry-turbulence interactions in scramjet flows...BILLIG, F. S., R. BAURLE, AND C. TAM 1999 Design and Analysis of Streamline Traced Hypersonic Inlets. AIAA Paper 1999-4974. BILLIG, F.S., AND

Filtering of elastic waves by opal-based hypersonic crystal.

Science.gov (United States)

Salasyuk, Alexey S; Scherbakov, Alexey V; Yakovlev, Dmitri R; Akimov, Andrey V; Kaplyanskii, Alexander A; Kaplan, Saveliy F; Grudinkin, Sergey A; Nashchekin, Alexey V; Pevtsov, Alexander B; Golubev, Valery G; Berstermann, Thorsten; Brüggemann, Christian; Bombeck, Michael; Bayer, Manfred

2010-04-14

We report experiments in which high quality silica opal films are used as three-dimensional hypersonic crystals in the 10 GHz range. Controlled sintering of these structures leads to well-defined elastic bonding between the submicrometer-sized silica spheres, due to which a band structure for elastic waves is formed. The sonic crystal properties are studied by injection of a broadband elastic wave packet with a femtosecond laser. Depending on the elastic bonding strength, the band structure separates long-living surface acoustic waves with frequencies in the complete band gap from bulk waves with band frequencies that propagate into the crystal leading to a fast decay.

Applications of Radiative Heating for Space Exploration

Science.gov (United States)

Brandis, Aaron

2017-01-01

Vehicles entering planetary atmospheres at high speeds (6 - 12 kms) experience intense heating by flows with temperatures of the order 10 000K. The flow around the vehicle experiences significant dissociation and ionization and is characterized by thermal and chemical non-equilibrium near the shock front, relaxing toward equilibrium. Emission from the plasma is intense enough to impart a significant heat flux on the entering spacecraft, making it necessary to predict the magnitude of radiative heating. Shock tubes represent a unique method capable of characterizing these processes in a flight-similar environment. The Electric Arc Shock tube (EAST) facility is one of the only facilities in its class, able to produce hypersonic flows at speeds up to Mach 50. This talk will review the characterization of radiation measured in EAST with simulations by the codes DPLR and NEQAIR, and in particular, focus on the impact these analyses have on recent missions to explore the solar system.

Control Relevant Modeling and Design of Scramjet-Powered Hypersonic Vehicles

Science.gov (United States)

Dickeson, Jeffrey James

This report provides an overview of scramjet-powered hypersonic vehicle modeling and control challenges. Such vehicles are characterized by unstable non-minimum phase dynamics with significant coupling and low thrust margins. Recent trends in hypersonic vehicle research are summarized. To illustrate control relevant design issues and tradeoffs, a generic nonlinear 3DOF longitudinal dynamics model capturing aero-elastic-propulsive interactions for wedge-shaped vehicle is used. Limitations of the model are discussed and numerous modifications have been made to address control relevant needs. Two different baseline configurations are examined over a two-stage to orbit ascent trajectory. The report highlights how vehicle level-flight static (trim) and dynamic properties change over the trajectory. Thermal choking constraints are imposed on control system design as a direct consequence of having a finite FER margin. The implication of this state-dependent nonlinear FER margin constraint, the right half plane (RHP) zero, and lightly damped flexible modes, on control system bandwidth (BW) and FPA tracking has been discussed. A control methodology has been proposed that addresses the above dynamics while providing some robustness to modeling uncertainty. Vehicle closure (the ability to fly a trajectory segment subject to constraints) is provided through a proposed vehicle design methodology. The design method attempts to use open loop metrics whenever possible to design the vehicle. The design method is applied to a vehicle/control law closed loop nonlinear simulation for validation. The 3DOF longitudinal modeling results are validated against a newly released NASA 6DOF code.

A Compact Tunable Diode Laser Absorption Spectrometer to Monitor CO2 at 2.7 µm Wavelength in Hypersonic Flows

Directory of Open Access Journals (Sweden)

Raphäel Vallon

2010-06-01

Full Text Available Since the beginning of the Mars planet exploration, the characterization of carbon dioxide hypersonic flows to simulate a spaceship’s Mars atmosphere entry conditions has been an important issue. We have developed a Tunable Diode Laser Absorption Spectrometer with a new room-temperature operating antimony-based distributed feedback laser (DFB diode laser to characterize the velocity, the temperature and the density of such flows. This instrument has been tested during two measurement campaigns in a free piston tunnel cold hypersonic facility and in a high enthalpy arc jet wind tunnel. These tests also demonstrate the feasibility of mid-infrared fiber optics coupling of the spectrometer to a wind tunnel for integrated or local flow characterization with an optical probe placed in the flow.

Large carbon cluster thin film gauges for measuring aerodynamic heat transfer rates in hypersonic shock tunnels

International Nuclear Information System (INIS)

Srinath, S; Reddy, K P J

2015-01-01

Different types of Large Carbon Cluster (LCC) layers are synthesized by a single-step pyrolysis technique at various ratios of precursor mixture. The aim is to develop a fast responsive and stable thermal gauge based on a LCC layer which has relatively good electrical conduction in order to use it in the hypersonic flow field. The thermoelectric property of the LCC layer has been studied. It is found that these carbon clusters are sensitive to temperature changes. Therefore suitable thermal gauges were developed for blunt cone bodies and were tested in hypersonic shock tunnels at a flow Mach number of 6.8 to measure aerodynamic heating. The LCC layer of this thermal gauge encounters high shear forces and a hostile environment for test duration in the range of a millisecond. The results are favorable to use large carbon clusters as a better sensor than a conventional platinum thin film gauge in view of fast responsiveness and stability. (paper)

Radiation Coupling with the FUN3D Unstructured-Grid CFD Code

Science.gov (United States)

Wood, William A.

2012-01-01

The HARA radiation code is fully-coupled to the FUN3D unstructured-grid CFD code for the purpose of simulating high-energy hypersonic flows. The radiation energy source terms and surface heat transfer, under the tangent slab approximation, are included within the fluid dynamic ow solver. The Fire II flight test, at the Mach-31 1643-second trajectory point, is used as a demonstration case. Comparisons are made with an existing structured-grid capability, the LAURA/HARA coupling. The radiative surface heat transfer rates from the present approach match the benchmark values within 6%. Although radiation coupling is the focus of the present work, convective surface heat transfer rates are also reported, and are seen to vary depending upon the choice of mesh connectivity and FUN3D ux reconstruction algorithm. On a tetrahedral-element mesh the convective heating matches the benchmark at the stagnation point, but under-predicts by 15% on the Fire II shoulder. Conversely, on a mixed-element mesh the convective heating over-predicts at the stagnation point by 20%, but matches the benchmark away from the stagnation region.

Unsteady heat-flux measurements of second-mode instability waves in a hypersonic flat-plate boundary layer

Science.gov (United States)

Kegerise, Michael A.; Rufer, Shann J.

2016-08-01

In this paper, we report on the application of the atomic layer thermopile (ALTP) heat-flux sensor to the measurement of laminar-to-turbulent transition in a hypersonic flat-plate boundary layer. The centerline of the flat-plate model was instrumented with a streamwise array of ALTP sensors, and the flat-plate model was exposed to a Mach 6 freestream over a range of unit Reynolds numbers. Here, we observed an unstable band of frequencies that are associated with second-mode instability waves in the laminar boundary layer that forms on the flat-plate surface. The measured frequencies, group velocities, phase speeds, and wavelengths of these instability waves are consistent with data previously reported in the literature. Heat flux time series, and the Morlet wavelet transforms of them, revealed the wave-packet nature of the second-mode instability waves. In addition, a laser-based radiative heating system was used to measure the frequency response functions (FRF) of the ALTP sensors used in the wind tunnel test. These measurements were used to assess the stability of the sensor FRFs over time and to correct spectral estimates for any attenuation caused by the finite sensor bandwidth.

Influence of radiation on predictive accuracy in numerical simulations of the thermal environment in industrial buildings with buoyancy-driven natural ventilation

International Nuclear Information System (INIS)

Meng, Xiaojing; Wang, Yi; Liu, Tiening; Xing, Xiao; Cao, Yingxue; Zhao, Jiangping

2016-01-01

Highlights: • The effects of radiation on predictive accuracy in numerical simulations were studied. • A scaled experimental model with a high-temperature heat source was set up. • Simulation results were discussed considering with and without radiation model. • The buoyancy force and the ventilation rate were investigated. - Abstract: This paper investigates the effects of radiation on predictive accuracy in the numerical simulations of industrial buildings. A scaled experimental model with a high-temperature heat source is set up and the buoyancy-driven natural ventilation performance is presented. Besides predicting ventilation performance in an industrial building, the scaled model in this paper is also used to generate data to validate the numerical simulations. The simulation results show good agreement with the experiment data. The effects of radiation on predictive accuracy in the numerical simulations are studied for both pure convection model and combined convection and radiation model. Detailed results are discussed regarding the temperature and velocity distribution, the buoyancy force and the ventilation rate. The temperature and velocity distributions through the middle plane are presented for the pure convection model and the combined convection and radiation model. It is observed that the overall temperature and velocity magnitude predicted by the simulations for pure convection were significantly greater than those for the combined convection and radiation model. In addition, the Grashof number and the ventilation rate are investigated. The results show that the Grashof number and the ventilation rate are greater for the pure convection model than for the combined convection and radiation model.

Nonequilibrium radiation behind a strong shock wave in CO{sub 2}-N{sub 2}

Energy Technology Data Exchange (ETDEWEB)

Rond, C. [Universite de Provence - IUSTI, 5 rue Enrico Fermi, Marseille 13013 (France)], E-mail: rond@coria.fr; Boubert, P.; Felio, J.-M.; Chikhaoui, A. [Universite de Provence - IUSTI, 5 rue Enrico Fermi, Marseille 13013 (France)

2007-11-09

This work presents experiments reproducing plasma re-entry for one trajectory point of a Martian mission. The typical facility to investigate such hypersonic flow is shock tube; here we used the free-piston shock tube TCM2. Measurements of radiative flux behind the shock wave are realized thanks to time-resolved emission spectroscopy which is calibrated in intensity. As CN violet system is the main radiator in near UV-visible range, we have focused our study on its spectrum. Moreover a physical model, based on a multi-temperature kinetic code and a radiative code, for calculation of non equilibrium radiation behind a shock wave is developed for CO{sub 2}-N{sub 2}-Ar mixtures. Comparisons between experiments and calculations show that standard kinetic models (Park, McKenzie) are inefficient to reproduce our experimental results. Therefore we propose new rate coefficients in particular for the dissociation of CO{sub 2}, showing the way towards a better description of the chemistry of the mixture.

Aerodynamic Modeling of Oscillating Wing in Hypersonic Flow: a Numerical Study

Science.gov (United States)

Zhu, Jian; Hou, Ying-Yu; Ji, Chen; Liu, Zi-Qiang

2016-06-01

Various approximations to unsteady aerodynamics are examined for the unsteady aerodynamic force of a pitching thin double wedge airfoil in hypersonic flow. Results of piston theory, Van Dyke’s second-order theory, Newtonian impact theory, and CFD method are compared in the same motion and Mach number effects. The results indicate that, for this thin double wedge airfoil, Newtonian impact theory is not suitable for these Mach number, while piston theory and Van Dyke’s second-order theory are in good agreement with CFD method for Ma<7.

The 1 × 1 m hypersonic wind tunnel Kochel/Tullahoma 1940-1960

Science.gov (United States)

Eckardt, Dietrich

2015-03-01

Peenemünde and Cape Canaveral mark cornerstones of space history. Kochel in Southern Germany and Tullahoma in Tennessee, USA also belong in this category. The technically unique Kochel wind tunnel was part of the German long-distance missile development strategy, planned and prepared in secret before the beginning of World War II. A 57 MW closed-circuit wind tunnel facility with 1 × 1 m measuring section was planned for continuous-flow simulation at high Mach numbers Ma 7-10. In the early 1940 s a site beside the Walchensee Power Station at Kochel am See in Upper Bavaria, Germany was chosen to provide the required altitude difference of 200 m for the hydraulic turbine drives. The preparatory activities for the erection of this impressive hypersonic wind tunnel facility were pushed ahead until an enforced temporary pause in September 1944. In early May 1945 US troops occupied the area and, in due course, scientists of General Arnold's Scientific Advisory Group, the `von Kármán team', ordered the transfer to the USA of available equipment, design materials and other paperwork. Here, at the Arnold Engineering Development Center (AEDC) Tullahoma, TN this `Tunnel A' was built to begin operation around 1957. The testing was conducted on the Mach 7 experimental aircraft X-15, space shuttle developments and still secret investigations on unmanned hypersonic vehicles.

Studies on the propagation of relativistic plasma waves in high density plasmas produced by hypersonic ionizing shock waves

International Nuclear Information System (INIS)

Williams, R.L.; Johnson, J.A. III

1993-01-01

The feasibility of using an ionizing shock wave to produce high density plasmas suitable for the propagation large amplitude relativistic plasma waves is being investigated. A 20 kv arc driven shock tube of coaxial geometry produces a hypersonic shock wave (10 p > 10 17 cm -3 ). The shock can be made to reflect off the end of the tube, collide with its wake, and thus increase the plasma density further. After reflecting, the plasma is at rest. The shock speed is measured using piezoelectric pressure probes and the ion density is measured using laser induced fluorescence (LIF) techniques on argon 488.0 nm and 422.8 nm lines. The future plans are to excite large amplitude relativistic plasma waves in this plasma by either injecting a short pulse laser (Laser Wake Field Scheme), two beating lasers (Plasma Beat Wave Scheme), or a short bunch of relativistic electrons (Plasma Wake Field Scheme). Results of recent computational and theoretical studies, as well as initial experimental measurements on the plasma using LIF, are reported. Implications for the application of high density plasmas produced in this way to such novel schemes as the plasma wave accelerator, photon accelerator, plasma wave undulator, and also plasma lens, are discussed. The effect of plasma turbulence is also discussed

On Stability and Control of SSTO Spaceplane in Super-and Hypersonic Ascending Phase

OpenAIRE

DIEKMANN, Andreas; MATSUSHIMA, Koichi; 松島, 弘一

1991-01-01

The natural dynamic stability of a single stage to orbit (SSTO) National Aerospace Laboratory Spaceplane Configuration is evaluated at seven reference points on a super-to hypersonic and constant dynamic pressure ascent trajectory. It is shown that dynamic instability occurs in the longitudinal and lateral motion during wide parts of the regarded trajectory. To counteract these instabilities a simple output feedback control is introduced to achieve a pole assignment of the dominant modes acco...

A compact tunable diode laser absorption spectrometer to monitor CO2 at 2.7 μm wavelength in hypersonic flows.

Science.gov (United States)

Vallon, Raphäel; Soutadé, Jacques; Vérant, Jean-Luc; Meyers, Jason; Paris, Sébastien; Mohamed, Ajmal

2010-01-01

Since the beginning of the Mars planet exploration, the characterization of carbon dioxide hypersonic flows to simulate a spaceship's Mars atmosphere entry conditions has been an important issue. We have developed a Tunable Diode Laser Absorption Spectrometer with a new room-temperature operating antimony-based distributed feedback laser (DFB) diode laser to characterize the velocity, the temperature and the density of such flows. This instrument has been tested during two measurement campaigns in a free piston tunnel cold hypersonic facility and in a high enthalpy arc jet wind tunnel. These tests also demonstrate the feasibility of mid-infrared fiber optics coupling of the spectrometer to a wind tunnel for integrated or local flow characterization with an optical probe placed in the flow.

Computations of the Shock Waves at Hypersonic Velocities Taken into Account the Chemical Reactions that Appear in the Air at High Temperatures

Directory of Open Access Journals (Sweden)

Mihai Leonida NICULESCU

2015-09-01

Full Text Available The temperature in the nose region of a hypersonic vehicle can be extremely high, for example, reaching approximately 11 000 K at a Mach number of 36 (Apollo reentry. The bow shock wave is normal, or nearly normal, in the nose region of a blunt body, and the gas temperature behind this shock wave can be enormous at hypersonic speeds. In this case, the assumption of a calorically perfect nonreacting gas with the ratio of specific heats  of 1.4 gives an unrealistically high value of temperature. Therefore, the proper inclusion of chemically reacting effects is vital to the calculation of an accurate normal shock wave temperature.

Assessment of CFD Hypersonic Turbulent Heating Rates for Space Shuttle Orbiter

Science.gov (United States)

Wood, William A.; Oliver, A. Brandon

2011-01-01

Turbulent CFD codes are assessed for the prediction of convective heat transfer rates at turbulent, hypersonic conditions. Algebraic turbulence models are used within the DPLR and LAURA CFD codes. The benchmark heat transfer rates are derived from thermocouple measurements of the Space Shuttle orbiter Discovery windward tiles during the STS-119 and STS-128 entries. The thermocouples were located underneath the reaction-cured glass coating on the thermal protection tiles. Boundary layer transition flight experiments conducted during both of those entries promoted turbulent flow at unusually high Mach numbers, with the present analysis considering Mach 10{15. Similar prior comparisons of CFD predictions directly to the flight temperature measurements were unsatisfactory, showing diverging trends between prediction and measurement for Mach numbers greater than 11. In the prior work, surface temperatures and convective heat transfer rates had been assumed to be in radiative equilibrium. The present work employs a one-dimensional time-accurate conduction analysis to relate measured temperatures to surface heat transfer rates, removing heat soak lag from the flight data, in order to better assess the predictive accuracy of the numerical models. The turbulent CFD shows good agreement for turbulent fuselage flow up to Mach 13. But on the wing in the wake of the boundary layer trip, the inclusion of tile conduction effects does not explain the prior observed discrepancy in trends between simulation and experiment; the flight heat transfer measurements are roughly constant over Mach 11-15, versus an increasing trend with Mach number from the CFD.

Radiation-driven Turbulent Accretion onto Massive Black Holes

Energy Technology Data Exchange (ETDEWEB)

Park, KwangHo; Wise, John H.; Bogdanović, Tamara, E-mail: kwangho.park@physics.gatech.edu [Center for Relativistic Astrophysics, School of Physics, Georgia Institute of Technology, Atlanta, GA 30332 (United States)

2017-09-20

Accretion of gas and interaction of matter and radiation are at the heart of many questions pertaining to black hole (BH) growth and coevolution of massive BHs and their host galaxies. To answer them, it is critical to quantify how the ionizing radiation that emanates from the innermost regions of the BH accretion flow couples to the surrounding medium and how it regulates the BH fueling. In this work, we use high-resolution three-dimensional (3D) radiation-hydrodynamic simulations with the code Enzo , equipped with adaptive ray-tracing module Moray , to investigate radiation-regulated BH accretion of cold gas. Our simulations reproduce findings from an earlier generation of 1D/2D simulations: the accretion-powered UV and X-ray radiation forms a highly ionized bubble, which leads to suppression of BH accretion rate characterized by quasi-periodic outbursts. A new feature revealed by the 3D simulations is the highly turbulent nature of the gas flow in vicinity of the ionization front. During quiescent periods between accretion outbursts, the ionized bubble shrinks in size and the gas density that precedes the ionization front increases. Consequently, the 3D simulations show oscillations in the accretion rate of only ∼2–3 orders of magnitude, significantly smaller than 1D/2D models. We calculate the energy budget of the gas flow and find that turbulence is the main contributor to the kinetic energy of the gas but corresponds to less than 10% of its thermal energy and thus does not contribute significantly to the pressure support of the gas.

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

Numerical simulation of air hypersonic flows with equilibrium chemical reactions

Science.gov (United States)

Emelyanov, Vladislav; Karpenko, Anton; Volkov, Konstantin

2018-05-01

The finite volume method is applied to solve unsteady three-dimensional compressible Navier-Stokes equations on unstructured meshes. High-temperature gas effects altering the aerodynamics of vehicles are taken into account. Possibilities of the use of graphics processor units (GPUs) for the simulation of hypersonic flows are demonstrated. Solutions of some test cases on GPUs are reported, and a comparison between computational results of equilibrium chemically reacting and perfect air flowfields is performed. Speedup of solution on GPUs with respect to the solution on central processor units (CPUs) is compared. The results obtained provide promising perspective for designing a GPU-based software framework for practical applications.

Hypersonic rarefied-flow aerodynamics inferred from Shuttle Orbiter acceleration measurements

Science.gov (United States)

Blanchard, R. C.; Hinson, E. W.

1989-01-01

Data obtained from multiple flights of sensitive accelerometers on the Space Shuttle Orbiter during reentry have been used to develop an improved aerodynamic model for the Orbiter normal- and axial-force coefficients in hypersonic rarefied flow. The lack of simultaneous atmospheric density measurements was overcome in part by using the ratio of normal-to-axial acceleration, in which density cancels, as a constraint. Differences between the preflight model and the flight-acceleration-derived model in the continuum regime are attributed primarily to real gas effects. New insights are gained into the variation of the force coefficients in the transition between the continuum regime and free molecule flow.

An implicit flux-split algorithm to calculate hypersonic flowfields in chemical equilibrium

Science.gov (United States)

Palmer, Grant

1987-01-01

An implicit, finite-difference, shock-capturing algorithm that calculates inviscid, hypersonic flows in chemical equilibrium is presented. The flux vectors and flux Jacobians are differenced using a first-order, flux-split technique. The equilibrium composition of the gas is determined by minimizing the Gibbs free energy at every node point. The code is validated by comparing results over an axisymmetric hemisphere against previously published results. The algorithm is also applied to more practical configurations. The accuracy, stability, and versatility of the algorithm have been promising.

Simulation of the influence high-frequency (2 MHz) capacitive gas discharge and magnetic field on the plasma sheath near a surface in hypersonic gas flow

International Nuclear Information System (INIS)

Schweigert, I. V.

2012-01-01

The plasma sheath near the surface of a hypersonic aircraft formed under associative ionization behind the shock front shields the transmission and reception of radio signals. Using two-dimensional kinetic particle-in-cell simulations, we consider the change in plasma-sheath parameters near a flat surface in a hypersonic flow under the action of electrical and magnetic fields. The combined action of a high-frequency 2-MHz capacitive discharge, a constant voltage, and a magnetic field on the plasma sheath allows the local electron density to be reduced manyfold.

Active disturbance rejection attitude control for a hypersonic reentry vehicle with actuator saturation

Directory of Open Access Journals (Sweden)

Hongjiu Yang

2017-05-01

Full Text Available In this article, nonlinear uncertainty has been investigated for a hypersonic reentry vehicle subject to actuator saturation via active disturbance rejection control technology. A nonlinear extended state observer is designed to estimate “total disturbances,” which is compensated with a linear controller. Both convergence of the nonlinear extended state observer and stabilization of the closed-loop system are studied in this article. Some simulation results are given to illustrate the effectiveness of the proposed method.

Heat Transfer and Failure Mode Analyses of Ultrahigh-Temperature Ceramic Thermal Protection System of Hypersonic Vehicles

Directory of Open Access Journals (Sweden)

Tianbao Cheng

2014-01-01

Full Text Available The transient temperature distribution of the ultrahigh-temperature ceramic (UHTC thermal protection system (TPS of hypersonic vehicles is calculated using finite volume method. Convective cooling enables a balance of heat increment and loss to be achieved. The temperature in the UHTC plate at the balance is approximately proportional to the surface heat flux and is approximately inversely proportional to the convective heat transfer coefficient. The failure modes of the UHTCs are presented by investigating the thermal stress field of the UHTC TPS under different thermal environments. The UHTCs which act as the thermal protection materials of hypersonic vehicles can fail because of the tensile stress at the lower surface, an area above the middle plane, and the upper surface as well as because of the compressive stress at the upper surface. However, the area between the lower surface and the middle plane and a small area near the upper surface are relatively safe. Neither the compressive stress nor the tensile stress will cause failure of these areas.

Optimal Control of Hypersonic Planning Maneuvers Based on Pontryagin’s Maximum Principle

Directory of Open Access Journals (Sweden)

A. Yu. Melnikov

2015-01-01

Full Text Available The work objective is the synthesis of simple analytical formula of the optimal roll angle of hypersonic gliding vehicles for conditions of quasi-horizontal motion, allowing its practical implementation in onboard control algorithms.The introduction justifies relevance, formulates basic control tasks, and describes a history of scientific research and achievements in the field concerned. The author reveals a common disadvantage of the other authors’ methods, i.e. the problem of practical implementation in onboard control algorithms.The similar tasks of hypersonic maneuvers are systemized according to the type of maneuver, control parameters and limitations.In the statement of the problem the glider launched horizontally with a suborbital speed glides passive in the static Atmosphere on a spherical surface of constant radius in the Central field of gravitation.The work specifies a system of equations of motion in the inertial spherical coordinate system, sets the limits on the roll angle and optimization criteria at the end of the flight: high speed or azimuth and the minimum distances to the specified geocentric points.The solution.1 A system of equations of motion is transformed by replacing the time argument with another independent argument – the normal equilibrium overload. The Hamiltonian and the equations of mated parameters are obtained using the Pontryagin’s maximum principle. The number of equations of motion and mated vector is reduced.2 The mated parameters were expressed by formulas using current movement parameters. The formulas are proved through differentiation and substitution in the equations of motion.3 The Formula of optimal roll-position control by condition of maximum is obtained. After substitution of mated parameters, the insertion of constants, and trigonometric transformations the Formula of the optimal roll angle is obtained as functions of the current parameters of motion.The roll angle is expressed as the ratio

Two-dimensional simulations of magnetically-driven instabilities

International Nuclear Information System (INIS)

Peterson, D.; Bowers, R.; Greene, A.E.; Brownell, J.

1986-01-01

A two-dimensional Eulerian MHD code is used to study the evolution of magnetically-driven instabilities in cylindrical geometry. The code incorporates an equation of state, resistivity, and radiative cooling model appropriate for an aluminum plasma. The simulations explore the effects of initial perturbations, electrical resistivity, and radiative cooling on the growth and saturation of the instabilities. Comparisons are made between the 2-D simulations, previous 1-D simulations, and results from the Pioneer experiments of the Los Alamos foil implosion program

Lagrangian Particle Tracking in a Discontinuous Galerkin Method for Hypersonic Reentry Flows in Dusty Environments

Science.gov (United States)

Ching, Eric; Lv, Yu; Ihme, Matthias

2017-11-01

Recent interest in human-scale missions to Mars has sparked active research into high-fidelity simulations of reentry flows. A key feature of the Mars atmosphere is the high levels of suspended dust particles, which can not only enhance erosion of thermal protection systems but also transfer energy and momentum to the shock layer, increasing surface heat fluxes. Second-order finite-volume schemes are typically employed for hypersonic flow simulations, but such schemes suffer from a number of limitations. An attractive alternative is discontinuous Galerkin methods, which benefit from arbitrarily high spatial order of accuracy, geometric flexibility, and other advantages. As such, a Lagrangian particle method is developed in a discontinuous Galerkin framework to enable the computation of particle-laden hypersonic flows. Two-way coupling between the carrier and disperse phases is considered, and an efficient particle search algorithm compatible with unstructured curved meshes is proposed. In addition, variable thermodynamic properties are considered to accommodate high-temperature gases. The performance of the particle method is demonstrated in several test cases, with focus on the accurate prediction of particle trajectories and heating augmentation. Financial support from a Stanford Graduate Fellowship and the NASA Early Career Faculty program are gratefully acknowledged.

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.

A line driven Rayleigh-Taylor-type instability in hot stars

International Nuclear Information System (INIS)

Nelson, G.D.; Hearn, A.G.

1978-01-01

The existence of a Rayleigh-Taylor-type instability in the atmosphere of hot stars, driven by the radiative force associated with impurity ion resonance lines, is demonstrated. In a hot star with an effective temperature of 50 000 K, the instability will grow exponentially with a time scale of approximately 50 s in the layers where the stellar wind velocity is 5% of the thermal velocity of the ion. As a result, radially symmetric stellar winds driven by resonance line radiative forces will break up in small horizontal scale lengths. The energy fed into the instability provides a possible source of mechanical heating in the atmosphere for a chromosphere or corona. (orig.) [de

Dynamic surface tracking controller design for a constrained hypersonic vehicle based on disturbance observer

Directory of Open Access Journals (Sweden)

Fang Wang

2017-05-01

Full Text Available The tracking control problem of a flexible air-breathing hypersonic vehicle subjects to aerodynamic parameter uncertainty and input constraint is investigated by combining nonlinear disturbance observer and dynamic surface control. To design controller simply, a control-oriented model is firstly derived and divided into two subsystems, velocity subsystem and altitude subsystem based on the engineering backgrounds of flexible air-breathing hypersonic vehicle. In every subsystem, compounded disturbances are included to consider aerodynamic uncertainty and the effect of the flexible modes. Then, disturbance observer is not only used to handle the compounded disturbance but also to handle the input constraint, where the estimation error converges to a random small region through appropriately choosing the observer parameters. To sequel, the disturbance observer–based robust control scheme and the disturbance observer-based dynamic surface control scheme are developed for the velocity subsystem and altitude subsystem, respectively. Besides, novel filters are designed to alleviate the problem of “explosion of terms” induced by backstepping method. On the basis of Lyapunov stability theory, the presented control scheme can assure that tracking error converges to an arbitrarily small neighborhood around zero by rigorous theoretical analysis. At last, simulation result shows the effectiveness of the presented control method.

Weakly Ionized Plasmas in Hypersonics: Fundamental Kinetics and Flight Applications

International Nuclear Information System (INIS)

Macheret, Sergey

2005-01-01

The paper reviews some of the recent studies of applications of weakly ionized plasmas to supersonic/hypersonic flight. Plasmas can be used simply as means of delivering energy (heating) to the flow, and also for electromagnetic flow control and magnetohydrodynamic (MHD) power generation. Plasma and MHD control can be especially effective in transient off-design flight regimes. In cold air flow, nonequilibrium plasmas must be created, and the ionization power budget determines design, performance envelope, and the very practicality of plasma/MHD devices. The minimum power budget is provided by electron beams and repetitive high-voltage nanosecond pulses, and the paper describes theoretical and computational modeling of plasmas created by the beams and repetitive pulses. The models include coupled equations for non-local and unsteady electron energy distribution function (modeled in forward-back approximation), plasma kinetics, and electric field. Recent experimental studies at Princeton University have successfully demonstrated stable diffuse plasmas sustained by repetitive nanosecond pulses in supersonic air flow, and for the first time have demonstrated the existence of MHD effects in such plasmas. Cold-air hypersonic MHD devices are shown to permit optimization of scramjet inlets at Mach numbers higher than the design value, while operating in self-powered regime. Plasma energy addition upstream of the inlet throat can increase the thrust by capturing more air (Virtual Cowl), or it can reduce the flow Mach number and thus eliminate the need for an isolator duct. In the latter two cases, the power that needs to be supplied to the plasma would be generated by an MHD generator downstream of the combustor, thus forming the 'reverse energy bypass' scheme. MHD power generation on board reentry vehicles is also discussed

An unstructured shock-fitting solver for hypersonic plasma flows in chemical non-equilibrium

Science.gov (United States)

Pepe, R.; Bonfiglioli, A.; D'Angola, A.; Colonna, G.; Paciorri, R.

2015-11-01

A CFD solver, using Residual Distribution Schemes on unstructured grids, has been extended to deal with inviscid chemical non-equilibrium flows. The conservative equations have been coupled with a kinetic model for argon plasma which includes the argon metastable state as independent species, taking into account electron-atom and atom-atom processes. Results in the case of an hypersonic flow around an infinite cylinder, obtained by using both shock-capturing and shock-fitting approaches, show higher accuracy of the shock-fitting approach.

Planar channeled relativistic electrons and positrons in the field of resonant hypersonic wave

International Nuclear Information System (INIS)

Grigoryan, L.Sh.; Mkrtchyan, A.H.; Khachatryan, H.F.; Tonoyan, V.U.; Wagner, W.

2003-01-01

The wave function of a planar channeled relativistic particle (electron, positron) in a single crystal excited by longitudinal hypersonic vibrations (HVs) is determined. The obtained expression is valid for periodic (not necessarily harmonic) HV of desired profile and single crystals with an arbitrary periodic continuous potential. A revised formula for the wave number of HV that exert resonance influence on the state of a channeled particle was deduced to allow for non-linear effects due to the influence of HV

Hypersonic research engine project. Phase 2: Preliminary report on the performance of the HRE/AIM at Mach 6

Science.gov (United States)

Sun, Y. H.; Sainio, W. C.

1975-01-01

Test results of the Aerothermodynamic Integration Model are presented. A program was initiated to develop a hydrogen-fueled research-oriented scramjet for operation between Mach 3 and 8. The primary objectives were to investigate the internal aerothermodynamic characteristics of the engine, to provide realistic design parameters for future hypersonic engine development as well as to evaluate the ground test facility and testing techniques. The engine was tested at the NASA hypersonic tunnel facility with synthetic air at Mach 5, 6, and 7. The hydrogen fuel was heated up to 1500 R prior to injection to simulate a regeneratively cooled system. The engine and component performance at Mach 6 is reported. Inlet performance compared very well both with theory and with subscale model tests. Combustor efficiencies up to 95 percent were attained at an equivalence ratio of unity. Nozzle performance was lower than expected. The overall engine performance was computed using two different methods. The performance was also compared with test data from other sources.

Basic materials and structures aspects for hypersonic transport vehicles (HTV)

Science.gov (United States)

Steinheil, E.; Uhse, W.

A Mach 5 transport design is used to illustrate structural concepts and criteria for materials selections and also key technologies that must be followed in the areas of computational methods, materials and construction methods. Aside from the primary criteria of low weight, low costs, and conceivable risks, a number of additional requirements must be met, including stiffness and strength, corrosion resistance, durability, and a construction adequate for inspection, maintenance and repair. Current aircraft construction requirements are significantly extended for hypersonic vehicles. Additional consideration is given to long-duration temperature resistance of the airframe structure, the integration of large-volume cryogenic fuel tanks, computational tools, structural design, polymer matrix composites, and advanced manufacturing technologies.

Engineering the hypersonic phononic band gap of hybrid Bragg stacks.

Science.gov (United States)

Schneider, Dirk; Liaqat, Faroha; El Boudouti, El Houssaine; El Hassouani, Youssef; Djafari-Rouhani, Bahram; Tremel, Wolfgang; Butt, Hans-Jürgen; Fytas, George

2012-06-13

We report on the full control of phononic band diagrams for periodic stacks of alternating layers of poly(methyl methacrylate) and porous silica combining Brillouin light scattering spectroscopy and theoretical calculations. These structures exhibit large and robust on-axis band gaps determined by the longitudinal sound velocities, densities, and spacing ratio. A facile tuning of the gap width is realized at oblique incidence utilizing the vector nature of the elastic wave propagation. Off-axis propagation involves sagittal waves in the individual layers, allowing access to shear moduli at nanoscale. The full theoretical description discerns the most important features of the hypersonic one-dimensional crystals forward to a detailed understanding, a precondition to engineer dispersion relations in such structures.

Application of CLIPPER in the design of radiation history card for a radiation worker

International Nuclear Information System (INIS)

Datta, D.; Pendharkar, K.A.; Krishnamony, S.

1994-01-01

Radiation history card for the plant workers has been designed based on a PC software. The software is developed using CLIPPER language and is menu driven. The card gives instant information about the radiation data of an occupational worker useful for effective exposure control. (author). 1 tab

Optimal Growth in Hypersonic Boundary Layers

Science.gov (United States)

Paredes, Pedro; Choudhari, Meelan M.; Li, Fei; Chang, Chau-Lyan

2016-01-01

The linear form of the parabolized linear stability equations is used in a variational approach to extend the previous body of results for the optimal, nonmodal disturbance growth in boundary-layer flows. This paper investigates the optimal growth characteristics in the hypersonic Mach number regime without any high-enthalpy effects. The influence of wall cooling is studied, with particular emphasis on the role of the initial disturbance location and the value of the spanwise wave number that leads to the maximum energy growth up to a specified location. Unlike previous predictions that used a basic state obtained from a self-similar solution to the boundary-layer equations, mean flow solutions based on the full Navier-Stokes equations are used in select cases to help account for the viscous- inviscid interaction near the leading edge of the plate and for the weak shock wave emanating from that region. Using the full Navier-Stokes mean flow is shown to result in further reduction with Mach number in the magnitude of optimal growth relative to the predictions based on the self-similar approximation to the base flow.

An improved wavelength selection scheme for Monte Carlo solvers applied to hypersonic plasmas

International Nuclear Information System (INIS)

Feldick, Andrew; Modest, Michael F.

2011-01-01

A new databasing scheme is developed for Monte Carlo Ray Tracing methods applied to hypersonic planetary entry. In this scheme, the complex relationships for the emission wavelength selection of atomic and molecular species in nonequilibrium flows are simplified by developing random number relationships for individual transitions, as opposed to using relationships for the spectral emission coefficient of a given species. These new techniques speed up wavelength selection by about 2 orders of magnitude, and offer flexibility for use in weighted or part-spectrum Monte Carlo solvers.

Temperature-Driven Convection

Science.gov (United States)

Bohan, Richard J.; Vandegrift, Guy

2003-02-01

Warm air aloft is stable. This explains the lack of strong winds in a warm front and how nighttime radiative cooling can lead to motionless air that can trap smog. The stability of stratospheric air can be attributed to the fact that it is heated from above as ultraviolet radiation strikes the ozone layer. On the other hand, fluid heated from below is unstable and can lead to Bernard convection cells. This explains the generally turbulent nature of the troposphere, which receives a significant fraction of its heat directly from the Earth's warmer surface. The instability of cold fluid aloft explains the violent nature of a cold front, as well as the motion of Earth's magma, which is driven by radioactive heating deep within the Earth's mantle. This paper describes how both effects can be demonstrated using four standard beakers, ice, and a bit of food coloring.

Prospects for coherently driven nuclear radiation by Coulomb excitation

International Nuclear Information System (INIS)

Karamyan, S.A.; Carroll, J.J.

2006-01-01

Possible experiments are discussed in which the Coulomb excitation of nuclear isomers would be followed by sequential energy release. The possibility of the coherent Coulomb excitation of nuclei ensconced in a crystal by channeled relativistic heavy projectiles is considered. The phase shift between neighbor-nuclei excitations can be identical to the photon phase shift for emission in forward direction. Thus, the elementary string of atoms can radiate coherently with emission of characteristic nuclear γ rays and the intensity of the radiation could be increased due to the summation of amplitudes. The Moessbauer conditions should be important for this new type of collective radiation that could be promising in the context of the γ-lasing problem

Accelerator driven radiation clean nuclear power system conceptual research symposium

International Nuclear Information System (INIS)

Zhao Zhixiang

2000-06-01

The R and D of ADS (Accelerators Driven Subcritical System) in China introduced. 31 theses are presented. It includes the basic principle of ADS, accelerators, sub-critical reactors, neutron physics, nuclear data, partitioning and transmutation

Propulsion integration of hypersonic air-breathing vehicles utilizing a top-down design methodology

Science.gov (United States)

Kirkpatrick, Brad Kenneth

In recent years, a focus of aerospace engineering design has been the development of advanced design methodologies and frameworks to account for increasingly complex and integrated vehicles. Techniques such as parametric modeling, global vehicle analyses, and interdisciplinary data sharing have been employed in an attempt to improve the design process. The purpose of this study is to introduce a new approach to integrated vehicle design known as the top-down design methodology. In the top-down design methodology, the main idea is to relate design changes on the vehicle system and sub-system level to a set of over-arching performance and customer requirements. Rather than focusing on the performance of an individual system, the system is analyzed in terms of the net effect it has on the overall vehicle and other vehicle systems. This detailed level of analysis can only be accomplished through the use of high fidelity computational tools such as Computational Fluid Dynamics (CFD) or Finite Element Analysis (FEA). The utility of the top-down design methodology is investigated through its application to the conceptual and preliminary design of a long-range hypersonic air-breathing vehicle for a hypothetical next generation hypersonic vehicle (NHRV) program. System-level design is demonstrated through the development of the nozzle section of the propulsion system. From this demonstration of the methodology, conclusions are made about the benefits, drawbacks, and cost of using the methodology.

Feasibility study of a nonequilibrium MHD accelerator concept for hypersonic propulsion ground testing

International Nuclear Information System (INIS)

Lee, Ying-Ming; Simmons, G.A.; Nelson, G.L.

1995-01-01

A National Aeronautics and Space Administration (NASA) funded research study to evaluate the feasibility of using magnetohydrodynamic (MHD) body force accelerators to produce true air simulation for hypersonic propulsion ground testing is discussed in this paper. Testing over the airbreathing portion of a transatmospheric vehicle (TAV) hypersonic flight regime will require high quality air simulation for actual flight conditions behind a bow shock wave (forebody, pre-inlet region) for flight velocities up to Mach 16 and perhaps beyond. Material limits and chemical dissociation at high temperature limit the simulated flight Mach numbers in conventional facilities to less than Mach 12 for continuous and semi-continuous testing and less than Mach 7 for applications requiring true air chemistry. By adding kinetic energy directly to the flow, MHD accelerators avoid the high temperatures and pressures required in the reservoir region of conventional expansion facilities, allowing MHD to produce true flight conditions in flight regimes impossible with conventional facilities. The present study is intended to resolve some of the critical technical issues related to the operation of MHD at high pressure. Funding has been provided only for the first phase of a three to four year feasibility study that would culminate in the demonstration of MHD acceleration under conditions required to produce true flight conditions behind a bow shock wave to flight Mach numbers of 16 or greater. MHD critical issues and a program plan to resolve these are discussed

Tuning and switching the hypersonic phononic properties of elastic impedance contrast nanocomposites.

Science.gov (United States)

Sato, Akihiro; Pennec, Yan; Shingne, Nitin; Thurn-Albrecht, Thomas; Knoll, Wolfgang; Steinhart, Martin; Djafari-Rouhani, Bahram; Fytas, George

2010-06-22

Anodic aluminum oxide (AAO) containing arrays of aligned cylindrical nanopores infiltrated with polymers is a well-defined model system for the study of hypersound propagation in polymer nanocomposites. Hypersonic phononic properties of AAO/polymer nanocomposites such as phonon localization and anisotropic sound propagation can be tailored by adjusting elastic contrast and density contrast between the components. Changes in density and elastic properties of the component located in the nanopores induced by phase transitions allow reversible modification of the phononic band structure and mode switching. As example in case, the crystallization and melting of poly(vinylidene difluoride) inside AAO was investigated.

Hypersonic ground test capabilities for T and E testing above mach 8 ''a case where S and T meets T and E''

International Nuclear Information System (INIS)

Constantino, M; Miles, R; Brown, G; Laster, M; Nelson, G

1999-01-01

Simulation of hypersonic flight in ground test and evaluation (T and E) facilities is a challenging and formidable task, especially to fully duplicate the flight environment above approximately Mach 8 for most all hypersonic flight systems that have been developed, conceived, or envisioned. Basically, and for many years, the enabling technology to build such a ground test wind tunnel facility has been severely limited in the area of high-temperature, high-strength materials and thermal protection approaches. To circumvent the problems, various approaches have been used, including partial simulation and use of similarity laws and reduced test time. These approaches often are not satisfactory, i.e. operability and durability testing for air-breathing propulsion development and thermal protection development of many flight systems. Thus, there is a strong need for science and technology (S and T) community involvement in technology development to address these problems. This paper discusses a specific case where this need exists and where significant S and T involvement has made and continues to make significant contributions. The case discussed will be an Air Force research program currently underway to develop enabling technologies for a Mach 8-15 hypersonic true temperature wind tunnel with relatively long run time. The research is based on a concept proposed by princeton University using radiant or beamed energy into the supersonic nozzle flow

CFD code calibration and inlet-fairing effects on a 3D hypersonic powered-simulation model

Science.gov (United States)

Huebner, Lawrence D.; Tatum, Kenneth E.

1993-01-01

A three-dimensional (3D) computational study has been performed addressing issues related to the wind tunnel testing of a hypersonic powered-simulation model. The study consisted of three objectives. The first objective was to calibrate a state-of-the-art computational fluid dynamics (CFD) code in its ability to predict hypersonic powered-simulation flows by comparing CFD solutions with experimental surface pressure dam. Aftbody lower surface pressures were well predicted, but lower surface wing pressures were less accurately predicted. The second objective was to determine the 3D effects on the aftbody created by fairing over the inlet; this was accomplished by comparing the CFD solutions of two closed-inlet powered configurations with a flowing-inlet powered configuration. Although results at four freestream Mach numbers indicate that the exhaust plume tends to isolate the aftbody surface from most forebody flowfield differences, a smooth inlet fairing provides the least aftbody force and moment variation compared to a flowing inlet. The final objective was to predict and understand the 3D characteristics of exhaust plume development at selected points on a representative flight path. Results showed a dramatic effect of plume expansion onto the wings as the freestream Mach number and corresponding nozzle pressure ratio are increased.

Nonlinear control of linear parameter varying systems with applications to hypersonic vehicles

Science.gov (United States)

Wilcox, Zachary Donald

The focus of this dissertation is to design a controller for linear parameter varying (LPV) systems, apply it specifically to air-breathing hypersonic vehicles, and examine the interplay between control performance and the structural dynamics design. Specifically a Lyapunov-based continuous robust controller is developed that yields exponential tracking of a reference model, despite the presence of bounded, nonvanishing disturbances. The hypersonic vehicle has time varying parameters, specifically temperature profiles, and its dynamics can be reduced to an LPV system with additive disturbances. Since the HSV can be modeled as an LPV system the proposed control design is directly applicable. The control performance is directly examined through simulations. A wide variety of applications exist that can be effectively modeled as LPV systems. In particular, flight systems have historically been modeled as LPV systems and associated control tools have been applied such as gain-scheduling, linear matrix inequalities (LMIs), linear fractional transformations (LFT), and mu-types. However, as the type of flight environments and trajectories become more demanding, the traditional LPV controllers may no longer be sufficient. In particular, hypersonic flight vehicles (HSVs) present an inherently difficult problem because of the nonlinear aerothermoelastic coupling effects in the dynamics. HSV flight conditions produce temperature variations that can alter both the structural dynamics and flight dynamics. Starting with the full nonlinear dynamics, the aerothermoelastic effects are modeled by a temperature dependent, parameter varying state-space representation with added disturbances. The model includes an uncertain parameter varying state matrix, an uncertain parameter varying non-square (column deficient) input matrix, and an additive bounded disturbance. In this dissertation, a robust dynamic controller is formulated for a uncertain and disturbed LPV system. The developed

Multichannel High Resolution Wide Swath SAR Imaging for Hypersonic Air Vehicle with Curved Trajectory

Directory of Open Access Journals (Sweden)

Rui Zhou

2018-01-01

Full Text Available Synthetic aperture radar (SAR equipped on the hypersonic air vehicle in near space has many advantages over the conventional airborne SAR. However, its high-speed maneuvering characteristics with curved trajectory result in serious range migration, and exacerbate the contradiction between the high resolution and wide swath. To solve this problem, this paper establishes the imaging geometrical model matched with the flight trajectory of the hypersonic platform and the multichannel azimuth sampling model based on the displaced phase center antenna (DPCA technology. Furthermore, based on the multichannel signal reconstruction theory, a more efficient spectrum reconstruction model using discrete Fourier transform is proposed to obtain the azimuth uniform sampling data. Due to the high complexity of the slant range model, it is difficult to deduce the processing algorithm for SAR imaging. Thus, an approximate range model is derived based on the minimax criterion, and the optimal second-order approximate coefficients of cosine function are obtained using the two-population coevolutionary algorithm. On this basis, aiming at the problem that the traditional Omega-K algorithm cannot compensate the residual phase with the difficulty of Stolt mapping along the range frequency axis, this paper proposes an Exact Transfer Function (ETF algorithm for SAR imaging, and presents a method of range division to achieve wide swath imaging. Simulation results verify the effectiveness of the ETF imaging algorithm.

Multichannel High Resolution Wide Swath SAR Imaging for Hypersonic Air Vehicle with Curved Trajectory.

Science.gov (United States)

Zhou, Rui; Sun, Jinping; Hu, Yuxin; Qi, Yaolong

2018-01-31

Synthetic aperture radar (SAR) equipped on the hypersonic air vehicle in near space has many advantages over the conventional airborne SAR. However, its high-speed maneuvering characteristics with curved trajectory result in serious range migration, and exacerbate the contradiction between the high resolution and wide swath. To solve this problem, this paper establishes the imaging geometrical model matched with the flight trajectory of the hypersonic platform and the multichannel azimuth sampling model based on the displaced phase center antenna (DPCA) technology. Furthermore, based on the multichannel signal reconstruction theory, a more efficient spectrum reconstruction model using discrete Fourier transform is proposed to obtain the azimuth uniform sampling data. Due to the high complexity of the slant range model, it is difficult to deduce the processing algorithm for SAR imaging. Thus, an approximate range model is derived based on the minimax criterion, and the optimal second-order approximate coefficients of cosine function are obtained using the two-population coevolutionary algorithm. On this basis, aiming at the problem that the traditional Omega-K algorithm cannot compensate the residual phase with the difficulty of Stolt mapping along the range frequency axis, this paper proposes an Exact Transfer Function (ETF) algorithm for SAR imaging, and presents a method of range division to achieve wide swath imaging. Simulation results verify the effectiveness of the ETF imaging algorithm.

A hybrid CFD/characteristics method for fast characterization of hypersonic blunt forebody/inlet flow

Science.gov (United States)

Gao, WenZhi; Li, ZhuFei; Yang, JiMing

2015-10-01

A hybrid CFD/characteristic method (CCM) was proposed for fast design and evaluation of hypersonic inlet flow with nose bluntness, which targets the combined advantages of CFD and method of characteristics. Both the accuracy and efficiency of the developed CCM were verified reliably, and it was well demonstrated for the external surfaces design of a hypersonic forebody/inlet with nose bluntness. With the help of CCM method, effects of nose bluntness on forebody shock shapes and the flowfield qualities which dominate inlet performance were examined and analyzed on the two-dimensional and axisymmetric configurations. The results showed that blunt effects of a wedge forebody are more substantial than that of related cone cases. For a conical forebody with a properly blunted nose, a recovery of the shock front back to that of corresponding sharp nose is exhibited, accompanied with a gradually fading out of entropy layer effects. Consequently a simplification is thought to be reasonable for an axisymmetric inlet with a proper compression angle, and a blunt nose of limited radius can be idealized as a sharp nose, as the spillage and flow variations at the entrance are negligible, even though the nose scale increases to 10% cowl lip radius. Whereas for two-dimensional inlets, the blunt effects are substantial since not only the inlet capturing/starting capabilities, but also the flow uniformities are obviously degraded.

Measurement of temperature and pressure on the surface of a blunt cone using FBG sensor in hypersonic wind tunnel

Science.gov (United States)

Prasad, A. S. Guru; Sharath, U.; Nagarjun, V.; Hegde, G. M.; Asokan, S.

2013-09-01

Measurement of temperature and pressure exerted on the leeward surface of a blunt cone specimen has been demonstrated in the present work in a hypersonic wind tunnel using fiber Bragg grating (FBG) sensors. The experiments were conducted on a 30° apex-angle blunt cone with 51 mm base diameter at wind flow speeds of Mach 6.5 and 8.35 in a 300 mm hypersonic wind tunnel of Indian Institute of Science, Bangalore. A special pressure insensitive temperature sensor probe along with the conventional bare FBG sensors was used for explicit temperature and aerodynamic pressure measurement respectively on the leeward surface of the specimen. computational fluid dynamics (CFD) simulation of the flow field around the blunt cone specimen has also been carried out to obtain the temperature and pressure at conditions analogous to experiments. The results obtained from FBG sensors and the CFD simulations are found to be in good agreement with each other.

Measurement of temperature and pressure on the surface of a blunt cone using FBG sensor in hypersonic wind tunnel

International Nuclear Information System (INIS)

Guru Prasad, A S; Sharath, U; Asokan, S; Nagarjun, V; Hegde, G M

2013-01-01

Measurement of temperature and pressure exerted on the leeward surface of a blunt cone specimen has been demonstrated in the present work in a hypersonic wind tunnel using fiber Bragg grating (FBG) sensors. The experiments were conducted on a 30° apex-angle blunt cone with 51 mm base diameter at wind flow speeds of Mach 6.5 and 8.35 in a 300 mm hypersonic wind tunnel of Indian Institute of Science, Bangalore. A special pressure insensitive temperature sensor probe along with the conventional bare FBG sensors was used for explicit temperature and aerodynamic pressure measurement respectively on the leeward surface of the specimen. computational fluid dynamics (CFD) simulation of the flow field around the blunt cone specimen has also been carried out to obtain the temperature and pressure at conditions analogous to experiments. The results obtained from FBG sensors and the CFD simulations are found to be in good agreement with each other. (paper)

ICME-driven sheath regions deplete the outer radiation belt electrons

Science.gov (United States)

Hietala, H.; Kilpua, E. K.; Turner, D. L.

2013-12-01

It is an outstanding question in space weather and solar wind-magnetosphere interaction studies, why some storms result in an increase of the outer radiation belt electron fluxes, while others deplete them or produce no change. One approach to this problem is to look at differences in the storm drivers. Traditionally drivers have been classified to Stream Interaction Regions (SIRs) and Interplanetary Coronal Mass Ejections (ICMEs). However, an 'ICME event' is a complex structure: The core is a magnetic cloud (MC; a clear flux rope structure). If the mass ejection is fast enough, it can drive a shock in front of it. This leads to the formation of a sheath region between the interplanetary shock and the leading edge of the MC. While both the sheath and the MC feature elevated solar wind speed, their other properties are very different. For instance, the sheath region has typically a much higher dynamic pressure than the magnetic cloud. Moreover, the sheath region has a high power in magnetic field and dynamic pressure Ultra Low Frequency (ULF) range fluctuations, while the MC is characterised by an extremely smooth magnetic field. Magnetic clouds have been recognised as important drivers magnetospheric activity since they can comprise long periods of very large southward Interplanetary Magnetic Field (IMF). Nevertheless, previous studies have shown that sheath regions can also act as storm drivers. In this study, we analyse the effects of ICME-driven sheath regions on the relativistic electron fluxes observed by GOES satellites on the geostationary orbit. We perform a superposed epoch analysis of 31 sheath regions from solar cycle 23. Our results show that the sheaths cause an approximately one order of magnitude decrease in the 24h-averaged electron fluxes. Typically the fluxes also stay below the pre-event level for more than two days. Further analysis reveals that the decrease does not depend on, e.g., whether the sheath interval contains predominantly northward

LPV H-infinity Control for the Longitudinal Dynamics of a Flexible Air-Breathing Hypersonic Vehicle

Science.gov (United States)

Hughes, Hunter Douglas

This dissertation establishes the method needed to synthesize and simulate an Hinfinity Linear Parameter-Varying (LPV) controller for a flexible air-breathing hypersonic vehicle model. A study was conducted to gain the understanding of the elastic effects on the open loop system. It was determined that three modes of vibration would be suitable for the hypersonic vehicle model. It was also discovered from the open loop study that there is strong coupling in the hypersonic vehicle states, especially between the angle of attack, pitch rate, pitch attitude, and the exible modes of the vehicle. This dissertation outlines the procedure for synthesizing a full state feedback Hinfinity LPV controller for the hypersonic vehicle. The full state feedback study looked at both velocity and altitude tracking for the exible vehicle. A parametric study was conducted on each of these controllers to see the effects of changing the number of gridding points in the parameter space and changing the parameter variation rate limits in the system on the robust performance of the controller. As a result of the parametric study, a 7 x 7 grid ranging from Mach 7 to Mach 9 in velocity and from 70,000 feet to 90,000 feet in altitude, and a parameter variation rate limit of [.5 200]T was used for both the velocity tracking and altitude tracking cases. The resulting Hinfinity robust performances were gamma = 2.2224 for the velocity tracking case and = 1:7582 for the altitude tracking case. A linear analysis was then conducted on five different selected trim points from the Hinfinity LPV controller. This was conducted for the velocity tracking and altitude tracking cases. The results of linear analysis show that there is a slight difference in the response of the Hinfinity LPV controller and the fixed point H infinity controller. For the tracking task, the Hinfinity controller responds more quickly, and has a lower Hinfinity performance value. Next, the H infinity LPV controller was simulated

Simulation of an hypersonic gas turbine ramjet engine intake in the supersonic regime

OpenAIRE

El Houas Ghouddana, Ismael

2017-01-01

Since the beginning of time, we have fixed our eyes in space, imagining the possibility to arrive there. After hundreds of years of investigation, in the 20th century, we have achieved this goal. Now, in the 21st century, making the space accessible is the new challenge which we have proposed. There are different ways in order to achieve this goal: reusable rockets, pico-satellites or hypersonic vehicles. The idea of using vehicles that are able of going from a runway to space is the base of ...

Multi-Disciplinary Design Optimization of Hypersonic Air-Breathing Vehicle

Science.gov (United States)

Wu, Peng; Tang, Zhili; Sheng, Jianda

2016-06-01

A 2D hypersonic vehicle shape with an idealized scramjet is designed at a cruise regime: Mach number (Ma) = 8.0, Angle of attack (AOA) = 0 deg and altitude (H) = 30kms. Then a multi-objective design optimization of the 2D vehicle is carried out by using a Pareto Non-dominated Sorting Genetic Algorithm II (NSGA-II). In the optimization process, the flow around the air-breathing vehicle is simulated by inviscid Euler equations using FLUENT software and the combustion in the combustor is modeled by a methodology based on the well known combination effects of area-varying pipe flow and heat transfer pipe flow. Optimization results reveal tradeoffs among total pressure recovery coefficient of forebody, lift to drag ratio of vehicle, specific impulse of scramjet engine and the maximum temperature on the surface of vehicle.

SINS/CNS Nonlinear Integrated Navigation Algorithm for Hypersonic Vehicle

Directory of Open Access Journals (Sweden)

Yong-jun Yu

2015-01-01

Full Text Available Celestial Navigation System (CNS has characteristics of accurate orientation and strong autonomy and has been widely used in Hypersonic Vehicle. Since the CNS location and orientation mainly depend upon the inertial reference that contains errors caused by gyro drifts and other error factors, traditional Strap-down Inertial Navigation System (SINS/CNS positioning algorithm setting the position error between SINS and CNS as measurement is not effective. The model of altitude azimuth, platform error angles, and horizontal position is designed, and the SINS/CNS tightly integrated algorithm is designed, in which CNS altitude azimuth is set as measurement information. GPF (Gaussian particle filter is introduced to solve the problem of nonlinear filtering. The results of simulation show that the precision of SINS/CNS algorithm which reaches 130 m using three stars is improved effectively.

Z-petawatt driven ion beam radiography development.

Energy Technology Data Exchange (ETDEWEB)

Schollmeier, Marius; Geissel, Matthias; Rambo, Patrick K.; Schwarz, Jens; Sefkow, Adam B.

2013-09-01

Laser-driven proton radiography provides electromagnetic field mapping with high spatiotemporal resolution, and has been applied to many laser-driven High Energy Density Physics (HEDP) experiments. Our report addresses key questions about the feasibility of ion radiography at the Z-Accelerator (%E2%80%9CZ%E2%80%9D), concerning laser configuration, hardware, and radiation background. Charged particle tracking revealed that radiography at Z requires GeV scale protons, which is out of reach for existing and near-future laser systems. However, it might be possible to perform proton deflectometry to detect magnetic flux compression in the fringe field region of a magnetized liner inertial fusion experiment. Experiments with the Z-Petawatt laser to enhance proton yield and energy showed an unexpected scaling with target thickness. Full-scale, 3D radiation-hydrodynamics simulations, coupled to fully explicit and kinetic 2D particle-in-cell simulations running for over 10 ps, explain the scaling by a complex interplay of laser prepulse, preplasma, and ps-scale temporal rising edge of the laser.

A CFD-based aerodynamic design procedure for hypersonic wind-tunnel nozzles

Science.gov (United States)

Korte, John J.

1993-01-01

A new procedure which unifies the best of current classical design practices, computational fluid dynamics (CFD), and optimization procedures is demonstrated for designing the aerodynamic lines of hypersonic wind-tunnel nozzles. The new procedure can be used to design hypersonic wind tunnel nozzles with thick boundary layers where the classical design procedure has been shown to break down. An efficient CFD code, which solves the parabolized Navier-Stokes (PNS) equations using an explicit upwind algorithm, is coupled to a least-squares (LS) optimization procedure. A LS problem is formulated to minimize the difference between the computed flow field and the objective function, consisting of the centerline Mach number distribution and the exit Mach number and flow angle profiles. The aerodynamic lines of the nozzle are defined using a cubic spline, the slopes of which are optimized with the design procedure. The advantages of the new procedure are that it allows full use of powerful CFD codes in the design process, solves an optimization problem to determine the new contour, can be used to design new nozzles or improve sections of existing nozzles, and automatically compensates the nozzle contour for viscous effects as part of the unified design procedure. The new procedure is demonstrated by designing two Mach 15, a Mach 12, and a Mach 18 helium nozzles. The flexibility of the procedure is demonstrated by designing the two Mach 15 nozzles using different constraints, the first nozzle for a fixed length and exit diameter and the second nozzle for a fixed length and throat diameter. The computed flow field for the Mach 15 least squares parabolized Navier-Stokes (LS/PNS) designed nozzle is compared with the classically designed nozzle and demonstrates a significant improvement in the flow expansion process and uniform core region.

Effect of local energy supply to a hypersonic flow on the drag of bodies with different nose bluntness

International Nuclear Information System (INIS)

Borzov, V.Yu.; Rybka, I.V.; Yur'ev, A.S.

1995-01-01

Parameters of the axisymmetric flow around bodies with different bluntness are compared in the case of constant energy supply to the main hypersonic flow. Flow structures, drag coefficients, and expenditure of energy on overcoming drag are analyzed with the effect of thermal energy on the flow taken into account for different bodies with equal volume

Hypersonic vehicle control law development using H(infinity) and micron-synthesis

Science.gov (United States)

Gregory, Irene M.; Mcminn, John D.; Shaughnessy, John D.; Chowdhry, Rajiv S.

1993-01-01

Hypersonic vehicle control law development using H(infinity) and mu-synthesis is discussed. Airbreathing SSTO vehicles has a mutli-faceted mission that includes orbital operations, as well as re-entry and descent culminating in horizontal landing. However, the most challenging part of the operations is the ascent to orbit. The airbreathing propulsion requires lengthy atmospheric flight that may last as long as 30 minutes and take the vehicle half way around the globe. The vehicles's ascent is characterized by tight payload to orbit margins which translate into minimum fuel orbit as the performance criteria. Issues discussed include: SSTO airbreathing vehicle issues; control system performance requirements; robust control law framework; H(infinity) controller frequency analysis; and mu controller frequency analysis.

On-design solutions of hypersonic flows past elliptic-cone derived waveriders

International Nuclear Information System (INIS)

Yoon, Bok Hyun

1992-01-01

The hypersonic flows past a class of elliptic-conederived waverider at the on-design condition are analyzed. A CFD(Computational Fluid Dynamics) algorithm due to Lawrence is utilized to numerically integrate the steady Euler equations. The singular behavior at the sharp leading-edge of a waverider where a bow shock is to be attached for the ideal situation makes the computation extremely difficult for convergence of numerical solution. Various types of grids are generated and tested for converged solutions. A new formula for more accurate waverider shape is established and by means of this new waverider configuration the reason for the shock stand-off which was detected in previous investigations is clarified in this paper. (Author)

Schlieren diagnostics of the Los Alamos hypersonic gas target neutron generator

International Nuclear Information System (INIS)

Haasz, A.A.; Lever, J.H.

1981-01-01

The gasdynamic behaviour of a planar model of the Los Alamos geometry hypersonic gas target neutron generator (GTNG) was investigated using Schlieren flow visualization photographs, static and total pressure and spill flow measurements. The model consisted of two symmetrical expansion nozzles with 220 μm throats producing a combined flow of about Mach 4 in the GTNG channel. Stagnation pressures of 100-800 kPa were used. Two basic flow configurations, spill line closed and spill line open, were studied in order to gain insight into the complex boundary layer development near the nozzle exit planes. Both flow configurations are discussed qualitatively, making use of the pressure measurements and theoretical analysis. (orig.)

Extreme ultraviolet spectroscopy of low pressure helium microwave driven discharges

Science.gov (United States)

Espinho, Susana; Felizardo, Edgar; Tatarova, Elena; Alves, Luis Lemos

2016-09-01

Surface wave driven discharges are reliable plasma sources that can produce high levels of vacuum and extreme ultraviolet radiation (VUV and EUV). The richness of the emission spectrum makes this type of discharge a possible alternative source in EUV/VUV radiation assisted applications. However, due to challenging experimental requirements, publications concerning EUV radiation emitted by microwave plasmas are scarce and a deeper understanding of the main mechanisms governing the emission of radiation in this spectral range is required. To this end, the EUV radiation emitted by helium microwave driven plasmas operating at 2.45 GHz has been studied for low pressure conditions. Spectral lines from excited helium atoms and ions were detected via emission spectroscopy in the EUV/VUV regions. Novel data concerning the spectral lines observed in the 23 - 33 nm wavelength range and their intensity behaviour with variation of the discharge operational conditions are presented. The intensity of all the spectral emissions strongly increases with the microwave power delivered to the plasma up to 400 W. Furthermore, the intensity of all the ion spectral emissions in the EUV range decreases by nearly one order of magnitude as the pressure was raised from 0.2 to 0.5 mbar. Work funded by FCT - Fundacao para a Ciencia e a Tecnologia, under Project UID/FIS/50010/2013 and grant SFRH/BD/52412/2013 (PD-F APPLAuSE).

Dynamic Testing of the NASA Hypersonic Project Combined Cycle Engine Testbed for Mode Transition Experiments

Science.gov (United States)

2011-01-01

NASA is interested in developing technology that leads to more routine, safe, and affordable access to space. Access to space using airbreathing propulsion systems has potential to meet these objectives based on Airbreathing Access to Space (AAS) system studies. To this end, the NASA Fundamental Aeronautics Program (FAP) Hypersonic Project is conducting fundamental research on a Turbine Based Combined Cycle (TBCC) propulsion system. The TBCC being studied considers a dual flow-path inlet system. One flow-path includes variable geometry to regulate airflow to a turbine engine cycle. The turbine cycle provides propulsion from take-off to supersonic flight. The second flow-path supports a dual-mode scramjet (DMSJ) cycle which would be initiated at supersonic speed to further accelerate the vehicle to hypersonic speed. For a TBCC propulsion system to accelerate a vehicle from supersonic to hypersonic speed, a critical enabling technology is the ability to safely and effectively transition from the turbine to the DMSJ-referred to as mode transition. To experimentally test methods of mode transition, a Combined Cycle Engine (CCE) Large-scale Inlet testbed was designed with two flow paths-a low speed flow-path sized for a turbine cycle and a high speed flow-path designed for a DMSJ. This testbed system is identified as the CCE Large-Scale Inlet for Mode Transition studies (CCE-LIMX). The test plan for the CCE-LIMX in the NASA Glenn Research Center (GRC) 10- by 10-ft Supersonic Wind Tunnel (10x10 SWT) is segmented into multiple phases. The first phase is a matrix of inlet characterization (IC) tests to evaluate the inlet performance and establish the mode transition schedule. The second phase is a matrix of dynamic system identification (SysID) experiments designed to support closed-loop control development at mode transition schedule operating points for the CCE-LIMX. The third phase includes a direct demonstration of controlled mode transition using a closed loop control

Analytical solutions of hypersonic type IV shock - shock interactions

Science.gov (United States)

Frame, Michael John

An analytical model has been developed to predict the effects of a type IV shock interaction at high Mach numbers. This interaction occurs when an impinging oblique shock wave intersects the most normal portion of a detached bow shock. The flowfield which develops is complicated and contains an embedded jet of supersonic flow, which may be unsteady. The jet impinges on the blunt body surface causing very high pressure and heating loads. Understanding this type of interaction is vital to the designers of cowl lips and leading edges on air- breathing hypersonic vehicles. This analytical model represents the first known attempt at predicting the geometry of the interaction explicitly, without knowing beforehand the jet dimensions, including the length of the transmitted shock where the jet originates. The model uses a hyperbolic equation for the bow shock and by matching mass continuity, flow directions and pressure throughout the flowfield, a prediction of the interaction geometry can be derived. The model has been shown to agree well with the flowfield patterns and properties of experiments and CFD, but the prediction for where the peak pressure is located, and its value, can be significantly in error due to a lack of sophistication in the model of the jet fluid stagnation region. Therefore it is recommended that this region of the flowfield be modeled in more detail and more accurate experimental and CFD measurements be used for validation. However, the analytical model has been shown to be a fast and economic prediction tool, suitable for preliminary design, or for understanding the interactions effects, including the basic physics of the interaction, such as the jet unsteadiness. The model has been used to examine a wide parametric space of possible interactions, including different Mach number, impinging shock strength and location, and cylinder radius. It has also been used to examine the interaction on power-law shaped blunt bodies, a possible candidate for

An improved flux-split algorithm applied to hypersonic flows in chemical equilibrium

Science.gov (United States)

Palmer, Grant

1988-01-01

An explicit, finite-difference, shock-capturing numerical algorithm is presented and applied to hypersonic flows assumed to be in thermochemical equilibrium. Real-gas chemistry is either loosely coupled to the gasdynamics by way of a Gibbs free energy minimization package or fully coupled using species mass conservation equations with finite-rate chemical reactions. A scheme is developed that maintains stability in the explicit, finite-rate formulation while allowing relatively high time steps. The codes use flux vector splitting to difference the inviscid fluxes and employ real-gas corrections to viscosity and thermal conductivity. Numerical results are compared against existing ballistic range and flight data. Flows about complex geometries are also computed.

Hypersonic aerodynamic characteristics of a family of power-law, wing body configurations

Science.gov (United States)

Townsend, J. C.

1973-01-01

The configurations analyzed are half-axisymmetric, power-law bodies surmounted by thin, flat wings. The wing planform matches the body shock-wave shape. Analytic solutions of the hypersonic small disturbance equations form a basis for calculating the longitudinal aerodynamic characteristics. Boundary-layer displacement effects on the body and the wing upper surface are approximated. Skin friction is estimated by using compressible, laminar boundary-layer solutions. Good agreement was obtained with available experimental data for which the basic theoretical assumptions were satisfied. The method is used to estimate the effects of power-law, fineness ratio, and Mach number variations at full-scale conditions. The computer program is included.

Development and characterization of a Z-pinch-driven hohlraum high-yield inertial confinement fusion target concept

International Nuclear Information System (INIS)

Cuneo, Michael E.; Vesey, Roger A.; Porter, John L. Jr.; Chandler, Gordon A.; Fehl, David L.; Gilliland, Terrance L.; Hanson, David L.; McGurn, John S.; Reynolds, Paul G.; Ruggles, Laurence E.; Seamen, Hans; Spielman, Rick B.; Struve, Ken W.; Stygar, William A.; Simpson, Walter W.; Torres, Jose A.; Wenger, David F.; Hammer, James H.; Rambo, Peter W.; Peterson, Darrell L.

2001-01-01

Initial experiments to study the Z-pinch-driven hohlraum high-yield inertial confinement fusion (ICF) concept of Hammer, Tabak, and Porter [Hammer et al., Phys. Plasmas 6, 2129 (1999)] are described. The relationship between measured pinch power, hohlraum temperature, and secondary hohlraum coupling ('hohlraum energetics') is well understood from zero-dimensional semianalytic, and two-dimensional view factor and radiation magnetohydrodynamics models. These experiments have shown the highest x-ray powers coupled to any Z-pinch-driven secondary hohlraum (26±5 TW), indicating the concept could scale to fusion yields of >200 MJ. A novel, single-sided power feed, double-pinch driven secondary that meets the pinch simultaneity requirements for polar radiation symmetry has also been developed. This source will permit investigation of the pinch power balance and hohlraum geometry requirements for ICF relevant secondary radiation symmetry, leading to a capsule implosion capability on the Z accelerator [Spielman et al., Phys. Plasmas 5, 2105 (1998)

The HYTHIRM Project: Flight Thermography of the Space Shuttle During the Hypersonic Re-entry

Science.gov (United States)

Horvath, Thomas J.; Tomek, Deborah M.; Berger, Karen T.; Zalameda, Joseph N.; Splinter, Scott C.; Krasa, Paul W.; Schwartz, Richard J.; Gibson, David M.; Tietjen, Alan B.; Tack, Steve

2010-01-01

This report describes a NASA Langley led endeavor sponsored by the NASA Engineering Safety Center, the Space Shuttle Program Office and the NASA Aeronautics Research Mission Directorate to demonstrate a quantitative thermal imaging capability. A background and an overview of several multidisciplinary efforts that culminated in the acquisition of high resolution calibrated infrared imagery of the Space Shuttle during hypervelocity atmospheric entry is presented. The successful collection of thermal data has demonstrated the feasibility of obtaining remote high-resolution infrared imagery during hypersonic flight for the accurate measurement of surface temperature. To maximize science and engineering return, the acquisition of quantitative thermal imagery and capability demonstration was targeted towards three recent Shuttle flights - two of which involved flight experiments flown on Discovery. In coordination with these two Shuttle flight experiments, a US Navy NP-3D aircraft was flown between 26-41 nautical miles below Discovery and remotely monitored surface temperature of the Orbiter at Mach 8.4 (STS-119) and Mach 14.7 (STS-128) using a long-range infrared optical package referred to as Cast Glance. This same Navy aircraft successfully monitored the Orbiter Atlantis traveling at approximately Mach 14.3 during its return from the successful Hubble repair mission (STS-125). The purpose of this paper is to describe the systematic approach used by the Hypersonic Thermodynamic Infrared Measurements team to develop and implement a set of mission planning tools designed to establish confidence in the ability of an imaging platform to reliably acquire, track and return global quantitative surface temperatures of the Shuttle during entry. The mission planning tools included a pre-flight capability to predict the infrared signature of the Shuttle. Such tools permitted optimization of the hardware configuration to increase signal-to-noise and to maximize the available

Employment of hypersonic glide vehicles: Proposed criteria for use

Energy Technology Data Exchange (ETDEWEB)

Olguin, Abel [Sandia National Lab. (SNL-NM), Albuquerque, NM (United States)

2014-07-01

Hypersonic Glide Vehicles (HGVs) are a type of reentry vehicle that couples the high speed of ballistic missiles with the maneuverability of aircraft. The HGV has been in development since the 1970s, and its technology falls under the category of Conventional Prompt Global Strike (CPGS) weapons. As noted by James M. Acton, a senior associate in the Nuclear Policy Program at the Carnegie Endowment, CPGS is a “missile in search of a mission.” With the introduction of any significant new military capability, a doctrine for use—including specifics regarding how, when and where it would be used, as well as tactics, training and procedures—must be clearly defined and understood by policy makers, military commanders, and planners. In this paper, benefits and limitations of the HGV are presented. Proposed criteria and four scenarios illustrate a possible method for assessing when to use an HGV.

Cerenkov Radiator Driven by a Superconducting RF Electron Gun

International Nuclear Information System (INIS)

Poole, B.R.; Harris, J.R.

2011-01-01

The Naval Postgraduate School (NPS), Niowave, Inc., and Boeing have recently demonstrated operation of the first superconducting RF electron gun based on a quarter wave resonator structure. In preliminary tests, this gun has produced 10 ps long bunches with charge in excess of 78 pC, and with beam energy up to 396 keV. Initial testing occurred at Niowave's Lansing, MI facility, but the gun and diagnostic beam line are planned for installation in California in the near future. The design of the diagnostic beam line is conducive to the addition of a Cerenkov radiator without interfering with other beam line operations. Design and simulations of a Cerenkov radiator, consisting of a dielectric lined waveguide will be presented. The dispersion relation for the structure is determined and the beam interaction is studied using numerical simulations. The characteristics of the microwave radiation produced in both the short and long bunch regimes will be presented.

Time dependent shear stress and temperature distribution over an insulated flat plate moving at hypersonic speed.

Science.gov (United States)

Rodkiewicz, C. M.; Gupta, R. N.

1971-01-01

The laminar two-dimensional flow over a stepwise accelerated flat plate moving with hypersonic speed at zero angle of attack is analysed. The governing equations in the self-similar form are linearized and solved numerically for small times. The solutions obtained are the deviations of the velocity and the temperature profiles from those of steady state. The presented results may be used to find the first order boundary layer induced pressure on the plate.

Hypersonic Experimental and Computational Capability, Improvement and Validation. Volume 2. (l’Hypersonique experimentale et de calcul - capacite, ameliorafion et validation)

Science.gov (United States)

1998-12-01

Reactive Gas Flows Within Shock Tunnels", Australian Journal of Physics, 37 (2) 157-177 (1984). 24 Hannemann , K., and Brenner, G., "Numeri- cal... Hannemann K., Butefisch K., Koppenwallner G. 1991 Review of the European Hypersonic Wind Tunnel Performance and Simulation Requirements. ESA Paper

CFD Validation Studies for Hypersonic Flow Prediction

Science.gov (United States)

Gnoffo, Peter A.

2001-01-01

A series of experiments to measure pressure and heating for code validation involving hypersonic, laminar, separated flows was conducted at the Calspan-University at Buffalo Research Center (CUBRC) in the Large Energy National Shock (LENS) tunnel. The experimental data serves as a focus for a code validation session but are not available to the authors until the conclusion of this session. The first set of experiments considered here involve Mach 9.5 and Mach 11.3 N2 flow over a hollow cylinder-flare with 30 degree flare angle at several Reynolds numbers sustaining laminar, separated flow. Truncated and extended flare configurations are considered. The second set of experiments, at similar conditions, involves flow over a sharp, double cone with fore-cone angle of 25 degrees and aft-cone angle of 55 degrees. Both sets of experiments involve 30 degree compressions. Location of the separation point in the numerical simulation is extremely sensitive to the level of grid refinement in the numerical predictions. The numerical simulations also show a significant influence of Reynolds number on extent of separation. Flow unsteadiness was easily introduced into the double cone simulations using aggressive relaxation parameters that normally promote convergence.

Determination of the hypersonic-continuum/rarefied-flow drag coefficient of the Viking lander capsule 1 aeroshell from flight data

Science.gov (United States)

Blanchard, R. C.; Walberg, G. D.

1980-01-01

Results of an investigation to determine the full scale drag coefficient in the high speed, low density regime of the Viking lander capsule 1 entry vehicle are presented. The principal flight data used in the study were from onboard pressure, mass spectrometer, and accelerometer instrumentation. The hypersonic continuum flow drag coefficient was unambiguously obtained from pressure and accelerometer data; the free molecule flow drag coefficient was indirectly estimated from accelerometer and mass spectrometer data; the slip flow drag coefficient variation was obtained from an appropriate scaling of existing experimental sphere data. Comparison of the flight derived drag hypersonic continuum flow regime except for Reynolds numbers from 1000 to 100,000, for which an unaccountable difference between flight and ground test data of about 8% existed. The flight derived drag coefficients in the free molecule flow regime were considerably larger than those previously calculated with classical theory. The general character of the previously determined temperature profile was not changed appreciably by the results of this investigation; however, a slightly more symmetrical temperature variation at the highest altitudes was obtained.

On Parametric Sensitivity of Reynolds-Averaged Navier-Stokes SST Turbulence Model: 2D Hypersonic Shock-Wave Boundary Layer Interactions

Science.gov (United States)

Brown, James L.

2014-01-01

Examined is sensitivity of separation extent, wall pressure and heating to variation of primary input flow parameters, such as Mach and Reynolds numbers and shock strength, for 2D and Axisymmetric Hypersonic Shock Wave Turbulent Boundary Layer interactions obtained by Navier-Stokes methods using the SST turbulence model. Baseline parametric sensitivity response is provided in part by comparison with vetted experiments, and in part through updated correlations based on free interaction theory concepts. A recent database compilation of hypersonic 2D shock-wave/turbulent boundary layer experiments extensively used in a prior related uncertainty analysis provides the foundation for this updated correlation approach, as well as for more conventional validation. The primary CFD method for this work is DPLR, one of NASA's real-gas aerothermodynamic production RANS codes. Comparisons are also made with CFL3D, one of NASA's mature perfect-gas RANS codes. Deficiencies in predicted separation response of RANS/SST solutions to parametric variations of test conditions are summarized, along with recommendations as to future turbulence approach.

BOW SHOCK FRAGMENTATION DRIVEN BY A THERMAL INSTABILITY IN LABORATORY ASTROPHYSICS EXPERIMENTS

Energy Technology Data Exchange (ETDEWEB)

Suzuki-Vidal, F.; Lebedev, S. V.; Pickworth, L. A.; Swadling, G. F.; Skidmore, J.; Hall, G. N.; Bennett, M.; Bland, S. N.; Burdiak, G.; De Grouchy, P.; Music, J.; Suttle, L. [Blackett Laboratory, Imperial College London, Prince Consort Road, London SW7 2BW (United Kingdom); Ciardi, A. [Sorbonne Universités, UPMC Univ. Paris 6, UMR 8112, LERMA, F-75005, Paris (France); Rodriguez, R.; Gil, J. M.; Espinosa, G. [Departamento de Fisica de la Universidad de Las Palmas de Gran Canaria, E-35017 Las Palmas de Gran Canaria (Spain); Hartigan, P. [Department of Physics and Astronomy, Rice University, 6100 S. Main, Houston, TX 77521-1892 (United States); Hansen, E.; Frank, A., E-mail: f.suzuki@imperial.ac.uk [Department of Physics and Astronomy, University of Rochester, Rochester, NY 14627 (United States)

2015-12-20

The role of radiative cooling during the evolution of a bow shock was studied in laboratory-astrophysics experiments that are scalable to bow shocks present in jets from young stellar objects. The laboratory bow shock is formed during the collision of two counterstreaming, supersonic plasma jets produced by an opposing pair of radial foil Z-pinches driven by the current pulse from the MAGPIE pulsed-power generator. The jets have different flow velocities in the laboratory frame, and the experiments are driven over many times the characteristic cooling timescale. The initially smooth bow shock rapidly develops small-scale nonuniformities over temporal and spatial scales that are consistent with a thermal instability triggered by strong radiative cooling in the shock. The growth of these perturbations eventually results in a global fragmentation of the bow shock front. The formation of a thermal instability is supported by analysis of the plasma cooling function calculated for the experimental conditions with the radiative packages ABAKO/RAPCAL.

Basic aspects of spallation radiation damage to materials

Energy Technology Data Exchange (ETDEWEB)

Wechsler, M.S.; Lin, C. [North Carolina State Univ., Raleigh, NC (United States); Sommer, W.F. [Los Alamos National Laboratory, NM (United States)

1995-10-01

The nature of radiation effects, as learned from investigations using reactor neutron irradiations, is reviewed, and its relevance to spallation radiation damage to materials in accelerator-driven neutron sources is discussed. Property changes upon irradiation are due to (1) displaced atoms, producing vacancy and interstitial defect clusters, which cause radiation hardening and embrittlement; (2) helium production, the helium then forming bubbles, which engenders high-temperature grain-boundary fracture; and (3) transmutations, which means that impurity concentrations are introduced. Methods for analyzing displacement production are related, and recent calculations of displacement cross sections using SPECTER and LAHET are described, with special reference to tungsten, a major candidate for a target material in accelerator-driven neutron systems.

Time-dependent mass loss from hot stars with and without radiative driving

International Nuclear Information System (INIS)

Castor, J.I.; Owocki, S.P.; Rybicki, G.B.

1988-01-01

A numerical hydrodynamics code is used to investigate two aspects of the winds of hot stars. The first is the question of the instability of the massive radiatively-driven wind of an O star that is caused by the line shape mechanism: modulation of the radiation force by velocity fluctuations. The evolution of this instability is studied in a model O star wind, and is found, /ital modulo/ some numerical uncertainty, to lead to wave structures that are compatible with observations of wind instabilities. The other area of investigation is of main-sequence B star winds. Attempts were made to simulate a radiatively-driven and a pulsation-driven wind in a B star, but in each case the wind turned out to be very weak. It is argued that the pulsation-driven wind model is not likely to apply to B stars. 28 refs., 11 figs

The physics of radiation driven ICF hohlraums

International Nuclear Information System (INIS)

Rosen, M.D.

1995-01-01

On the Nova Laser at LLNL, we have recently demonstrated many of the key elements required for assuring that the next proposed laser, the National Ignition Facility (NIF) will drive an Inertial Confinement Fusion (ICF) target to ignition. The target uses the recently declassified indirect drive (sometimes referred to as open-quotes radiation driveclose quotes) approach which converts laser light to x-rays inside a gold cylinder, which then acts as an x-ray open-quotes ovenclose quotes (called a hohlraum) to drive the fusion capsule in its center. On Nova we've demonstrated good understanding of the temperatures reached in hohlraums and of the ways to control the uniformity with which the x-rays drive the spherical fusion capsules. In this lecture we briefly review the fundamentals of ICF, and describe the capsule implosion symmetry advantages of the hohlraum approach. We then concentrate on a quantitative understanding of the scaling of radiation drive with hohlraum size and wall material, and with laser pulse length and power. We demonstrate that coupling efficiency of x-ray drive to the capsule increases as we proceed from Nova to the NIF and eventually to a reactor, thus increasing the gain of the system

Response-driven imaging biomarkers for predicting radiation necrosis of the brain

International Nuclear Information System (INIS)

Nazem-Zadeh, Mohammad-Reza; Chapman, Christopher H; Lawrence, Theodore S; Ten Haken, Randall K; Tsien, Christina I; Cao, Yue; Chenevert, Thomas

2014-01-01

Radiation necrosis is an uncommon but severe adverse effect of brain radiation therapy (RT). Current predictive models based on radiation dose have limited accuracy. We aimed to identify early individual response biomarkers based upon diffusion tensor (DT) imaging and incorporated them into a response model for prediction of radiation necrosis. Twenty-nine patients with glioblastoma received six weeks of intensity modulated RT and concurrent temozolomide. Patients underwent DT-MRI scans before treatment, at three weeks during RT, and one, three, and six months after RT. Cases with radiation necrosis were classified based on generalized equivalent uniform dose (gEUD) of whole brain and DT index early changes in the corpus callosum and its substructures. Significant covariates were used to develop normal tissue complication probability models using binary logistic regression. Seven patients developed radiation necrosis. Percentage changes of radial diffusivity (RD) in the splenium at three weeks during RT and at six months after RT differed significantly between the patients with and without necrosis (p = 0.05 and p = 0.01). Percentage change of RD at three weeks during RT in the 30 Gy dose–volume of the splenium and brain gEUD combined yielded the best-fit logistic regression model. Our findings indicate that early individual response during the course of RT, assessed by radial diffusivity, has the potential to aid the prediction of delayed radiation necrosis, which could provide guidance in dose-escalation trials. (paper)

Aerothermodynamics of expert ballistic vehicle at hypersonic speeds

Science.gov (United States)

Kharitonov, A. M.; Adamov, N. P.; Chirkashenko, V. F.; Mazhul, I. I.; Shpak, S. I.; Shiplyuk, A. N.; Vasenyov, L. G.; Zvegintsev, V. I.; Muylaert, J. M.

2012-01-01

The European EXPErimental Re-entry Test bed (EXPERT) vehicle is intended for studying various basic phenomena, such as the boundary-layer transition on blunted bodies, real gas effects during shock wave/boundary layer interaction, and effect of surface catalycity. Another task is to develop methods for recalculating the results of windtunnel experiments to flight conditions. The EXPERT program implies large-scale preflight research, in particular, various calculations with the use of advanced numerical methods, experimental studies of the models in various wind tunnels, and comparative analysis of data obtained for possible extrapolation of data to in-flight conditions. The experimental studies are performed in various aerodynamic centers of Europe and Russia under contracts with ESA-ESTEC. In particular, extensive experiments are performed at the Von Karman Institute for Fluid Dynamics (VKI, Belgium) and also at the DLR aerospace center in Germany. At ITAM SB RAS, the experimental studies of the EXPERT model characteristic were performed under ISTC Projects 2109, 3151, and 3550, in the T-313 supersonic wind tunnel and AT-303 hypersonic wind tunnel.

Combined free-stream disturbance measurements and receptivity studies in hypersonic wind tunnels by means of a slender wedge probe and direct numerical simulation

Science.gov (United States)

Wagner, Alexander; Schülein, Erich; Petervari, René; Hannemann, Klaus; Ali, Syed R. C.; Cerminara, Adriano; Sandham, Neil D.

2018-05-01

Combined free-stream disturbance measurements and receptivity studies in hypersonic wind tunnels were conducted by means of a slender wedge probe and direct numerical simulation. The study comprises comparative tunnel noise measurements at Mach 3, 6 and 7.4 in two Ludwieg tube facilities and a shock tunnel. Surface pressure fluctuations were measured over a wide range of frequencies and test conditions including harsh test environments not accessible to measurement techniques such as pitot probes and hot-wire anemometry. Quantitative results of the tunnel noise are provided in frequency ranges relevant for hypersonic boundary layer transition. In combination with the experimental studies, direct numerical simulations of the leading-edge receptivity to fast and slow acoustic waves were performed for the slender wedge probe at conditions corresponding to the experimental free-stream conditions. The receptivity to fast acoustic waves was found to be characterized by an early amplification of the induced fast mode. For slow acoustic waves an initial decay was found close to the leading edge. At all Mach numbers, and for all considered frequencies, the leading-edge receptivity to fast acoustic waves was found to be higher than the receptivity to slow acoustic waves. Further, the effect of inclination angles of the acoustic wave with respect to the flow direction was investigated. The combined numerical and experimental approach in the present study confirmed the previous suggestion that the slow acoustic wave is the dominant acoustic mode in noisy hypersonic wind tunnels.

Pressure-sensitive paint on a truncated cone in hypersonic flow at incidences

International Nuclear Information System (INIS)

Yang, L.; Erdem, E.; Zare-Behtash, H.; Kontis, K.; Saravanan, S.

2012-01-01

Highlights: ► Global pressure map over the truncated cone is obtained at various incidence angles in Mach 5 flow. ► Successful application of AA-PSP in hypersonic flow expands operation area of this technique. ► AA-PSP reveals complex three-dimensional pattern which is difficult for transducer to obtain. ► Quantitative data provides strong correlation with colour Schlieren and oil flow results. ► High spatial resolution pressure mappings identify small scale vortices and flow separation. - Abstract: The flow over a truncated cone is a classical and fundamental problem for aerodynamic research due to its three-dimensional and complicated characteristics. The flow is made more complex when examining high angles of incidence. Recently these types of flows have drawn more attention for the purposes of drag reduction in supersonic/hypersonic flows. In the present study the flow over a truncated cone at various incidences was experimentally investigated in a Mach 5 flow with a unit Reynolds number of 13.5 × 10 6 m −1 . The cone semi-apex angle is 15° and the truncation ratio (truncated length/cone length) is 0.5. The incidence of the model varied from −12° to 12° with 3° intervals relative to the freestream direction. The external flow around the truncated cone was visualised by colour Schlieren photography, while the surface flow pattern was revealed using the oil flow method. The surface pressure distribution was measured using the anodized aluminium pressure-sensitive paint (AA-PSP) technique. Both top and sideviews of the pressure distribution on the model surface were acquired at various incidences. AA-PSP showed high pressure sensitivity and captured the complicated flow structures which correlated well with the colour Schlieren and oil flow visualisation results.

Prediction and Validation of Mars Pathfinder Hypersonic Aerodynamic Data Base

Science.gov (United States)

Gnoffo, Peter A.; Braun, Robert D.; Weilmuenster, K. James; Mitcheltree, Robert A.; Engelund, Walter C.; Powell, Richard W.

1998-01-01

Postflight analysis of the Mars Pathfinder hypersonic, continuum aerodynamic data base is presented. Measured data include accelerations along the body axis and axis normal directions. Comparisons of preflight simulation and measurements show good agreement. The prediction of two static instabilities associated with movement of the sonic line from the shoulder to the nose and back was confirmed by measured normal accelerations. Reconstruction of atmospheric density during entry has an uncertainty directly proportional to the uncertainty in the predicted axial coefficient. The sensitivity of the moment coefficient to freestream density, kinetic models and center-of-gravity location are examined to provide additional consistency checks of the simulation with flight data. The atmospheric density as derived from axial coefficient and measured axial accelerations falls within the range required for sonic line shift and static stability transition as independently determined from normal accelerations.

Simulation of hypersonic rarefied flows with the immersed-boundary method

Science.gov (United States)

Bruno, D.; De Palma, P.; de Tullio, M. D.

2011-05-01

This paper provides a validation of an immersed boundary method for computing hypersonic rarefied gas flows. The method is based on the solution of the Navier-Stokes equation and is validated versus numerical results obtained by the DSMC approach. The Navier-Stokes solver employs a flexible local grid refinement technique and is implemented on parallel machines using a domain-decomposition approach. Thanks to the efficient grid generation process, based on the ray-tracing technique, and the use of the METIS software, it is possible to obtain the partitioned grids to be assigned to each processor with a minimal effort by the user. This allows one to by-pass the expensive (in terms of time and human resources) classical generation process of a body fitted grid. First-order slip-velocity boundary conditions are employed and tested for taking into account rarefied gas effects.

Pulsed power driven hohlraum research at Sandia National Laboratories

Energy Technology Data Exchange (ETDEWEB)

Leeper, R J; Alberts, T E; Allshouse, G A [Sandia Labs., Albuquerque, NM (United States); and others

1997-12-31

Three pulsed power driven hohlraum concepts are being investigated at Sandia National Laboratories. These hohlraums are driven by intense proton and Li ion beams as well as by two different types of z-pinch x-ray sources. The paper is an overview of the experiments that have been conducted on these hohlraum systems and discusses several new and novel hohlraum characterization diagnostics that have been developed for this work. These diagnostics include an active shock breakout measurement of hohlraum temperature and a new transmission grating spectrograph for detailed thermal radiation spectral measurements. (author). 3 figs., 6 refs.

Pulsed power driven hohlraum research at Sandia National Laboratories

International Nuclear Information System (INIS)

Leeper, R.J.; Alberts, T.E.; Allshouse, G.A.

1996-01-01

Three pulsed power driven hohlraum concepts are being investigated at Sandia National Laboratories. These hohlraums are driven by intense proton and Li ion beams as well as by two different types of z-pinch x-ray sources. The paper is an overview of the experiments that have been conducted on these hohlraum systems and discusses several new and novel hohlraum characterization diagnostics that have been developed for this work. These diagnostics include an active shock breakout measurement of hohlraum temperature and a new transmission grating spectrograph for detailed thermal radiation spectral measurements. (author). 3 figs., 6 refs

Hypersonic simulations using open-source CFD and DSMC solvers

Science.gov (United States)

Casseau, V.; Scanlon, T. J.; John, B.; Emerson, D. R.; Brown, R. E.

2016-11-01

Hypersonic hybrid hydrodynamic-molecular gas flow solvers are required to satisfy the two essential requirements of any high-speed reacting code, these being physical accuracy and computational efficiency. The James Weir Fluids Laboratory at the University of Strathclyde is currently developing an open-source hybrid code which will eventually reconcile the direct simulation Monte-Carlo method, making use of the OpenFOAM application called dsmcFoam, and the newly coded open-source two-temperature computational fluid dynamics solver named hy2Foam. In conjunction with employing the CVDV chemistry-vibration model in hy2Foam, novel use is made of the QK rates in a CFD solver. In this paper, further testing is performed, in particular with the CFD solver, to ensure its efficacy before considering more advanced test cases. The hy2Foam and dsmcFoam codes have shown to compare reasonably well, thus providing a useful basis for other codes to compare against.

A Two-Temperature Open-Source CFD Model for Hypersonic Reacting Flows, Part One: Zero-Dimensional Analysis

OpenAIRE

Vincent Casseau; Rodrigo C. Palharini; Thomas J. Scanlon; Richard E. Brown

2016-01-01

A two-temperature CFD (computational fluid dynamics) solver is a prerequisite to any spacecraft re-entry numerical study that aims at producing results with a satisfactory level of accuracy within realistic timescales. In this respect, a new two-temperature CFD solver, hy2Foam, has been developed within the framework of the open-source CFD platform OpenFOAM for the prediction of hypersonic reacting flows. This solver makes the distinct juncture between the trans-rotational and multiple vibrat...

Powerful FEM-generator driven by microsecond sheet beam

Energy Technology Data Exchange (ETDEWEB)

Agafonov, M A; Arzhannikov, A V; Sinitskij, S L; Tarasov, A V [Institute of Nuclear Physics, Novosibirsk (Russian Federation); Ginzburg, N S; Peskov, N Yu [Institute of Applied Physics, Nizhny Novgorod (Russian Federation)

1997-12-31

The results of experimental and theoretical investigations in the creation of a powerful mm-band generator driven by a sheet beam are presented. A microsecond pulse of mm-radiation with a 200 J energy content was obtained in the experiments. The possibility of increasing this energy content up to tens of kJ was demonstrated. 3 figs., 8 refs.

Assessment of CFD Capability for Hypersonic Shock Wave Laminar Boundary Layer Interactions

Directory of Open Access Journals (Sweden)

Mehrnaz Rouhi Youssefi

2017-04-01

Full Text Available The goal of this study is to assess CFD capability for the prediction of shock wave laminar boundary layer interactions at hypersonic velocities. More specifically, the flow field over a double-cone configuration is simulated using both perfect gas and non-equilibrium Navier–Stokes models. Computations are compared with recent experimental data obtained from measurements conducted in the LENS XX (Large Energy National Shock Expansion Tunnel Version 2 at the Calspan University of Buffalo Research Center (CUBRC. Four separate cases of freestream conditions are simulated to examine the models for a range of stagnation enthalpies from 5.44 MJ/kg to 21.77 MJ/kg and Mach numbers from 10.9 to 12.82.

Adaptive Finite-Time Control for a Flexible Hypersonic Vehicle with Actuator Fault

Directory of Open Access Journals (Sweden)

Jie Wang

2013-01-01

Full Text Available The problem of robust fault-tolerant tracking control is investigated. Simulation on the longitudinal model of a flexible air-breathing hypersonic vehicle (FAHV with actuator faults and uncertainties is conducted. In order to guarantee that the velocity and altitude track their desired commands in finite time with the partial loss of actuator effectiveness, an adaptive fault-tolerant control strategy is presented based on practical finite-time sliding mode method. The adaptive update laws are used to estimate the upper bound of uncertainties and the minimum value of actuator efficiency factor. Finally, simulation results show that the proposed control strategy is effective in rejecting uncertainties even in the presence of actuator faults.

Tip-to-tail numerical simulation of a hypersonic air-breathing engine with ethylene fuel

Science.gov (United States)

Dharavath, Malsur; Manna, P.; Chakraborty, Debasis

2016-11-01

End to end CFD simulations of external and internal flow paths of an ethylene fueled hypersonic airbreathing vehicle with including forebody, horizontal fins, vertical fins, intake, combustor, single expansion ramp nozzle are carried out. The performance of the scramjet combustor and vehicle net thrust-drag is calculated for hypersonic cruise condition. Three-dimensional Navier-Stokes equations are solved along with SST-k-ω turbulence model using the commercial CFD software CFX-14. Single step chemical reaction based on fast chemistry assumption is used for combustion of gaseous ethylene fuel. Simulations captured complex shock structures including the shocks generated from the vehicle nose and compression ramps, impingement of cowl-shock on vehicle undersurface and its reflection in the intake and combustor etc. Various thermochemical parameters are analyzed and performance parameters are evaluated for nonreacting and reacting cases. Very good mixing ( 98%) of fuel with incoming air stream is observed. Positive thrust-drag margins are obtained for fuel equivalence ratio of 0.6 and computed combustion efficiency is observed to be 94 %. Effect of equivalence ratio on the vehicle performance is studied parametrically. Though the combustion efficiency has come down by 8% for fuel equivalence ratio of 0.8, net vehicle thrust is increased by 44%. Heat flux distribution on the various walls of the whole vehicle including combustor is estimated for the isothermal wall condition of 1000 K in reacting flow. Higher local heat flux values are observed at all the leading edges of the vehicle (i.e., nose, wing, fin and cowl leading edges) and strut regions of the combustor.

LASNEX simulations of the classical and laser-driven Rayleigh-Taylor instability

International Nuclear Information System (INIS)

Mikaelian, K.O.

1990-01-01

We present the results of two-dimensional LASNEX simulations of the classical and laser-driven Rayleigh-Taylor instability. Our growth rates and eigenmodes for classical two- and three-fluid problems agree closely with the exact analytic expressions. We illustrate in several examples how perturbations feed through from one interface to another. For targets driven by a 1/4-μm laser at I=2x10 14 W/cm 2 our growth rates are 40--80 % of the classical case rates for wavelengths between 5 and 100 μm. We find that radiation transport has a stabilizing effect on the Rayleigh-Taylor instability, particularly at high intensities. A brief comparison with a laser-driven experiment is also presented

X-Ray-Driven Gamma Emission

International Nuclear Information System (INIS)

Carroll, J. J.; Karamian, S. A.; Rivlin, L. A.; Zadernovsky, A. A.

2001-01-01

X-ray-driven gamma emission describes processes that may release nuclear energy in a 'clean' way, as bursts of incoherent or coherent gamma rays without the production of radioactive by-products. Over the past decade, studies in this area, as a part of the larger field of quantum nucleonics, have gained tremendous momentum. Since 1987 it has been established that photons could trigger gamma emission from a long-lived metastable nuclear excited state of one nuclide and it appears likely that triggering in other isotopes will be demonstrated conclusively in the near future. With these experimental results have come new proposals for the creation of collective and avalanche-like incoherent gamma-ray bursts and even for the ultimate light source, a gamma-ray laser. Obviously, many applications would benefit from controlled bursts of gamma radiation, whether coherent or not. This paper reviews the experimental results and concepts for the production of gamma rays, driven by externally produced X-rays

Gluino reach and mass extraction at the LHC in radiatively-driven natural SUSY

Energy Technology Data Exchange (ETDEWEB)

Baer, Howard; Savoy, Michael; Sengupta, Dibyashree [University of Oklahoma, Department of Physics and Astronomy, Norman, OK (United States); Barger, Vernon [University of Wisconsin, Department of Physics, Madison, WI (United States); Gainer, James S.; Tata, Xerxes [University of Hawaii, Department of Physics and Astronomy, Honolulu, HI (United States); Huang, Peisi [University of Chicago, Enrico Fermi Institute, Chicago, IL (United States); HEP Division, Argonne National Laboratory, Argonne, IL (United States); Texas A and M University, Mitchell Institute for Fundamental Physics and Astronomy, College Station, TX (United States)

2017-07-15

Radiatively-driven natural SUSY (RNS) models enjoy electroweak naturalness at the 10% level while respecting LHC sparticle and Higgs mass constraints. Gluino and top-squark masses can range up to several TeV (with other squarks even heavier) but a set of light Higgsinos are required with mass not too far above m{sub h} ∝ 125 GeV. Within the RNS framework, gluinos dominantly decay via g → tt{sub 1}{sup *}, anti tt{sub 1} → t anti tZ{sub 1,2} or t anti bW{sub 1}{sup -} + c.c., where the decay products of the higgsino-like W{sub 1} and Z{sub 2} are very soft. Gluino pair production is, therefore, signaled by events with up to four hard b-jets and large E{sub T}. We devise a set of cuts to isolate a relatively pure gluino sample at the (high-luminosity) LHC and show that in the RNS model with very heavy squarks, the gluino signal will be accessible for m{sub g} < 2400 (2800) GeV for an integrated luminosity of 300 (3000) fb{sup -1}. We also show that the measurement of the rate of gluino events in the clean sample mentioned above allows for a determination of m{sub g} with a statistical precision of 2-5% (depending on the integrated luminosity and the gluino mass) over the range of gluino masses where a 5σ discovery is possible at the LHC. (orig.)

A Preliminary Study Associated with the Experimental Measurement of the Aero-Optic Characteristics of Hypersonic Configurations

Science.gov (United States)

1992-06-01

and Neubauer , R.A., "Experimental Studies of Pulsed Microwave Breakdown Effects in a Hypersonic Air Plasma," Calspan Report No. AA-2053-Y-2, AFCRL...perhaps 100 jim intervals. For example 16 images will be exposed on 128 x 128 pixels sectors of a 512 x 512 pixel CCD camera , all during a 3.2 ms period of...device uses a laser and CCD camera . Acoustic-optic beam deflectors will scan the LOS during the short duration test, allowing image exposure durations

Thermally driven convective cells and tokamak edge turbulence

International Nuclear Information System (INIS)

Thayer, D.R.; Diamond, P.H.

1987-07-01

A unified theory for the dynamics of thermally driven convective cell turbulence is presented. The cells are excited by the combined effects of radiative cooling and resistivity gradient drive. The model also includes impurity dynamics. Parallel thermal and impurity flows enhanced by turbulent radial duffusion regulate and saturate overlapping cells, even in regimes dominated by thermal instability. Transport coefficients and fluctuation levels characteristic of the saturated turbulence are calculated. It is found that the impurity radiation increases transport coefficients for high density plasmas, while the parallel conduction damping, elevated by radial diffusion, in turn quenches the thermal instability. The enhancement due to radiative cooling provides a resolution to the dilemma of explaining the experimental observation that potential fluctuations exceed density fluctuations in the edge plasma (e PHI/T/sub e/ > n/n 0 )

AGN Obscuration Through Dusty Infrared Dominated Flows. II. Multidimensional, Radiation-Hydrodynamics Modeling

Science.gov (United States)

Dorodnitsyn, Anton; Kallman, Tim; Bisno\\vatyiI-Kogan, Gennadyi

2011-01-01

We explore a detailed model in which the active galactic nucleus (AGN) obscuration results from the extinction of AGN radiation in a global ow driven by the pressure of infrared radiation on dust grains. We assume that external illumination by UV and soft X-rays of the dusty gas located at approximately 1pc away from the supermassive black hole is followed by a conversion of such radiation into IR. Using 2.5D, time-dependent radiation hydrodynamics simulations in a ux-limited di usion approximation we nd that the external illumination can support a geometrically thick obscuration via out ows driven by infrared radiation pressure in AGN with luminosities greater than 0:05 L(sub edd) and Compton optical depth, Tau(sub T) approx > & 1.

Generation of quasi-monoenergetic protons from a double-species target driven by the radiation pressure of an ultraintense laser pulse

Energy Technology Data Exchange (ETDEWEB)

Pae, Ki Hong [Center for Relativistic Laser Science, Institute for Basic Science, Gwangju 61005 (Korea, Republic of); Kim, Chul Min, E-mail: chulmin@gist.ac.kr [Center for Relativistic Laser Science, Institute for Basic Science, Gwangju 61005 (Korea, Republic of); Advanced Photonics Research Institute, Gwangju Institute of Science and Technology, Gwangju 61005 (Korea, Republic of); Nam, Chang Hee, E-mail: chnam@gist.ac.kr [Center for Relativistic Laser Science, Institute for Basic Science, Gwangju 61005 (Korea, Republic of); Department of Physics and Photon Science, Gwangju Institute of Science and Technology, Gwangju 61005 (Korea, Republic of)

2016-03-15

In laser-driven proton acceleration, generation of quasi-monoenergetic proton beams has been considered a crucial feature of the radiation pressure acceleration (RPA) scheme, but the required difficult physical conditions have hampered its experimental realization. As a method to generate quasi-monoenergetic protons under experimentally viable conditions, we investigated using double-species targets of controlled composition ratio in order to make protons bunched in the phase space in the RPA scheme. From a modified optimum condition and three-dimensional particle-in-cell simulations, we showed by varying the ion composition ratio of proton and carbon that quasi-monoenergetic protons could be generated from ultrathin plane targets irradiated with a circularly polarized Gaussian laser pulse. The proposed scheme should facilitate the experimental realization of ultrashort quasi-monoenergetic proton beams for unique applications in high field science.

Numerical simulations of radiation hydrodynamics and modeling of high temperature hohlraum cavities

International Nuclear Information System (INIS)

Gupta, N.K.; Godwal, B.K.

2003-10-01

A summary of our efforts towards the validation of radiation hydrodynamics and opacity models are presented. Effects of various parameters on the radiation temperature inside an inertial confinement fusion (ICF) hohlraum, the effects of non-local thermodynamic equilibrium conditions on emission and absorption, and the hydrodynamics of aluminium and gold foils driven by radiation are studied. LTE and non-LTE predictions for emitted radiation are compared with the experimental results and it is seen that non-LTE simulations show a marked improvement over LTE results. It is shown that the mixing of two high Z materials can lead to an enhancement in the Rosseland mean. An experimental study of soft x-ray emission from laser-irradiated Au-Cu mix-Z targets confirmed these predictions. It is seen that only multi group non-LTE radiation transport is able to explain experimentally observed features in the conversion efficiency of laser light to x-rays. One group radiation transport under predicts the radiation temperature. It is shown that erroneous results can be obtained if the space mesh in the hohlraum wall is not fine enough. Hydrodynamics of a wedge shaped aluminium foil driven by the hohlraum radiation is also presented and results are compared with NOVA laser experiments. Laser driven shock wave EOS and gold hohlraum experiments carried out at CAT are analyzed and they confirmed our theoretical estimates. (author)

Numerical Simulations of Turbulent Molecular Clouds Regulated by Radiation Feedback Forces. II. Radiation-Gas Interactions and Outflows

Science.gov (United States)

Raskutti, Sudhir; Ostriker, Eve C.; Skinner, M. Aaron

2017-12-01

Momentum deposition by radiation pressure from young, massive stars may help to destroy molecular clouds and unbind stellar clusters by driving large-scale outflows. We extend our previous numerical radiation hydrodynamic study of turbulent star-forming clouds to analyze the detailed interaction between non-ionizing UV radiation and the cloud material. Our simulations trace the evolution of gas and star particles through self-gravitating collapse, star formation, and cloud destruction via radiation-driven outflows. These models are idealized in that we include only radiation feedback and adopt an isothermal equation of state. Turbulence creates a structure of dense filaments and large holes through which radiation escapes, such that only ˜50% of the radiation is (cumulatively) absorbed by the end of star formation. The surface density distribution of gas by mass as seen by the central cluster is roughly lognormal with {σ }{ln{{Σ }}}=1.3{--}1.7, similar to the externally projected surface density distribution. This allows low surface density regions to be driven outwards to nearly 10 times their initial escape speed {v}{esc}. Although the velocity distribution of outflows is broadened by the lognormal surface density distribution, the overall efficiency of momentum injection to the gas cloud is reduced because much of the radiation escapes. The mean outflow velocity is approximately twice the escape speed from the initial cloud radius. Our results are also informative for understanding galactic-scale wind driving by radiation, in particular, the relationship between velocity and surface density for individual outflow structures and the resulting velocity and mass distributions arising from turbulent sources.

Aerodynamic heating in transitional hypersonic boundary layers: Role of second-mode instability

Science.gov (United States)

Zhu, Yiding; Chen, Xi; Wu, Jiezhi; Chen, Shiyi; Lee, Cunbiao; Gad-el-Hak, Mohamed

2018-01-01

The evolution of second-mode instabilities in hypersonic boundary layers and its effects on aerodynamic heating are investigated. Experiments are conducted in a Mach 6 wind tunnel using fast-response pressure sensors, fluorescent temperature-sensitive paint, and particle image velocimetry. Calculations based on parabolic stability equations and direct numerical simulations are also performed. It is found that second-mode waves, accompanied by high-frequency alternating fluid compression and expansion, produce intense aerodynamic heating in a small region that rapidly heats the fluid passing through it. As the second-mode waves decay downstream, the dilatation-induced aerodynamic heating decreases while its shear-induced counterpart keeps growing. The latter brings about a second growth of the surface temperature when transition is completed.

Radiation effects in materials for accelerator-driven neutron technologies

International Nuclear Information System (INIS)

Wechsler, M.S.; Lin, C.; Sommer, W.F.; Daemen, L.L.; Ferguson, P.D.

1997-01-01

The materials exposed to the most damaging radiation environments in an SNS (spallation neutron source) are those in the path of the incident proton beam. This includes target and window materials. These materials will experience damage from the incident protons and the spallation neutrons. The major solid targets in operating SNS's and under consideration for the 1--5 MW SNS's are W, U, and Pb. Tungsten is the target material at LANSCE, and is the project target material for an upgraded LANSCE target that is presently being designed. It is also the projected target material for the tritium producing SNS under design at LANL. In this paper, the authors present the results of spallation radiation damage calculations (displacement and He production) for tungsten

Experimental Study Of SHEFEX II Hypersonic Aerodynamics And Canard Efficiency In H2K

Science.gov (United States)

Neeb, D.; Gulhan, A.

2011-05-01

One main objective of the DLR SHEFEX programme is to prove that sharp edged vehicles are capable of performing a re-entry into earth atmosphere by using a simple thermal protection system consisting of flat ceramic tiles. In comparison to blunt nose configurations like the Space shuttle, which are normally used for re-entry configurations, the SHEFEX TPS design is able to significantly reduce the costs and complexity of TPS structures and simultaneously increase the aerodynamic performance of the flight vehicle [1], [2]. To study its characteristics and perform several defined in-flight experiments during re-entry, the vehicle’s attitude will be controlled actively by canards [3]. In the framework of the SHEFEX II project an experimental investigation has been conducted in the hypersonic wind tunnel H2K to characterize the aerodynamic performance of the vehicle in hypersonic flow regime. The model has a modular design to enable the study of a variety of different influencing parameters. Its 4 circumferential canards have been made independently adjustable to account for the simulation of different manoeuvre conditions. To study the control behaviour of the vehicle and validate CFD data, a variation of canard deflections, angle of attack and angle of sideslip have been applied. Tests have been carried out at Mach 7 and 8.7 with a Reynolds number sensitivity study at the lower Mach number. The model was equipped with a six component internal balance to realize accurate coefficient measurements. The flow topology has been analyzed using Schlieren images. Beside general aerodynamic performance and canard efficiencies, flow phenomena like shock impingement on the canards could be determined by Schlieren images as well as by the derived coefficients.

Space-marching gridless computation of steady supersonic/hypersonic flow

International Nuclear Information System (INIS)

Hui, W.H.; Hu, J.J.

2004-01-01

Most CFD work use Eulerian coordinates, which require generating a grid prior to flow filed computation. Despite three decades of research, grid generation is still a bottleneck of CFD, as it is time-consuming, tedious and requires specialized training. It will be shown in this paper that using the Unified Coordinates introduced by Hui et. al., there is no need for grid generation prior to flow computation; the grid is automatically generated while computing the flow. This greatly saves computing time. For steady supersonic/hypersonic flow, the Euler equations of gas dynamics are of hyperbolic type and a space-marching gridless computation along the streamlines - coordinate lines in the unified coordinates - is shown to be a complete success in that: (a) it is most robust, (b) it resolves both slip lines (also called contact lines) and shocks sharply, (c) its computing time is more than three orders of magnitude smaller than Eulerian computation and, (d) it by-passes the tedious and time-consuming grid generation stage which is needed in Eulerian computation. Three examples are given to justify these claims. (author)

Transition Delay in Hypersonic Boundary Layers via Optimal Perturbations

Science.gov (United States)

Paredes, Pedro; Choudhari, Meelan M.; Li, Fei

2016-01-01

The effect of nonlinear optimal streaks on disturbance growth in a Mach 6 axisymmetric flow over a 7deg half-angle cone is investigated in an e ort to expand the range of available techniques for transition control. Plane-marching parabolized stability equations are used to characterize the boundary layer instability in the presence of azimuthally periodic streaks. The streaks are observed to stabilize nominally planar Mack mode instabilities, although oblique Mack mode disturbances are destabilized. Experimentally measured transition onset in the absence of any streaks correlates with an amplification factor of N = 6 for the planar Mack modes. For high enough streak amplitudes, the transition threshold of N = 6 is not reached by the Mack mode instabilities within the length of the cone, but subharmonic first mode instabilities, which are destabilized by the presence of the streaks, reach N = 6 near the end of the cone. These results suggest a passive flow control strategy of using micro vortex generators to induce streaks that would delay transition in hypersonic boundary layers.

Design and Execution of the Hypersonic Inflatable Aerodynamic Decelerator Large-Article Wind Tunnel Experiment

Science.gov (United States)

Cassell, Alan M.

2013-01-01

The testing of 3- and 6-meter diameter Hypersonic Inflatable Aerodynamic Decelerator (HIAD) test articles was completed in the National Full-Scale Aerodynamics Complex 40 ft x 80 ft Wind Tunnel test section. Both models were stacked tori, constructed as 60 degree half-angle sphere cones. The 3-meter HIAD was tested in two configurations. The first 3-meter configuration utilized an instrumented flexible aerodynamic skin covering the inflatable aeroshell surface, while the second configuration employed a flight-like flexible thermal protection system. The 6-meter HIAD was tested in two structural configurations (with and without an aft-mounted stiffening torus near the shoulder), both utilizing an instrumented aerodynamic skin.

A kinetic-theory approach for computing chemical-reaction rates in upper-atmosphere hypersonic flows.

Science.gov (United States)

Gallis, Michael A; Bond, Ryan B; Torczynski, John R

2009-09-28

Recently proposed molecular-level chemistry models that predict equilibrium and nonequilibrium reaction rates using only kinetic theory and fundamental molecular properties (i.e., no macroscopic reaction-rate information) are investigated for chemical reactions occurring in upper-atmosphere hypersonic flows. The new models are in good agreement with the measured Arrhenius rates for near-equilibrium conditions and with both measured rates and other theoretical models for far-from-equilibrium conditions. Additionally, the new models are applied to representative combustion and ionization reactions and are in good agreement with available measurements and theoretical models. Thus, molecular-level chemistry modeling provides an accurate method for predicting equilibrium and nonequilibrium chemical-reaction rates in gases.

Soft X-Ray Measurements of Z-Pinch-Driven Vacuum Hohlraums

International Nuclear Information System (INIS)

Baker, K.L.; Porter, J.L.; Ruggles, L.E.; Chandler, G.A.; Deeney, Chris; Varas, M.; Moats, Ann; Struve, Ken; Torres, J.; McGurn, J.; Simpson, W.W.; Fehl, D.L.; Chrien, R.E.; Matuska, W.; Idzorek, G.C.

1999-01-01

This article reports the experimental characterization of a z-pinch driven-vacuum hohlraum. The authors have measured soft x-ray fluxes of 5 x 10 12 W/cm 2 radiating from the walls of hohlraums which are 2.4--2.5 cm in diameter by 1 cm tall. The x-ray source used to drive these hohlraums was a z-pinch consisting of a 300 wire tungsten array driven by a 2 MA, 100 ns current pulse. In this hohlraum geometry, the z-pinch x-ray source can produce energies in excess of 800 kJ and powers in excess of 100 TW to drive these hohlraums. The x-rays released in these hohlraums represent greater than a factor of 25 in energy and more than a factor of three in x-ray power over previous laboratory-driven hohlraums

Band structure of cavity-type hypersonic phononic crystals fabricated by femtosecond laser-induced two-photon polymerization

Energy Technology Data Exchange (ETDEWEB)

Rakhymzhanov, A. M.; Utegulov, Z. N., E-mail: zhutegulov@nu.edu.kz, E-mail: fytas@mpip-mainz.mpg.de [Department of Physics, School of Science and Technology, Nazarbayev University, Astana 010000 (Kazakhstan); Optics Laboratory, National Laboratory Astana, Nazarbayev University, Astana 10000 (Kazakhstan); Gueddida, A. [Institut d' Electronique, Microélectronique et Nanotechnologie, 59650 Villeneuve d' Ascq (France); LPMR, Département de Physique, Faculté des Sciences, Université Mohamed I, 60000 Oujda (Morocco); Alonso-Redondo, E. [Max Planck Institute of Polymer Research, Ackermannweg 10, 55128 Mainz (Germany); Perevoznik, D.; Kurselis, K. [Laser Zentrum Hannover e.V., 30419 Hannover (Germany); Chichkov, B. N. [Laser Zentrum Hannover e.V., 30419 Hannover (Germany); Institute of Laser and Information Technologies RAS, Moscow, 142092 Troitsk (Russian Federation); El Boudouti, E. H. [LPMR, Département de Physique, Faculté des Sciences, Université Mohamed I, 60000 Oujda (Morocco); Djafari-Rouhani, B. [Institut d' Electronique, Microélectronique et Nanotechnologie, 59650 Villeneuve d' Ascq (France); Fytas, G., E-mail: zhutegulov@nu.edu.kz, E-mail: fytas@mpip-mainz.mpg.de [Max Planck Institute of Polymer Research, Ackermannweg 10, 55128 Mainz (Germany); Department of Materials Science, University of Crete and FORTH, 71110 Heraklion (Greece)

2016-05-16

The phononic band diagram of a periodic square structure fabricated by femtosecond laser pulse-induced two photon polymerization is recorded by Brillouin light scattering (BLS) at hypersonic (GHz) frequencies and computed by finite element method. The theoretical calculations along the two main symmetry directions quantitatively capture the band diagrams of the air- and liquid-filled structure and moreover represent the BLS intensities. The theory helps identify the observed modes, reveals the origin of the observed bandgaps at the Brillouin zone boundaries, and unravels direction dependent effective medium behavior.

Analysis of directly driven ICF targets

International Nuclear Information System (INIS)

Velarde, G.; Aragones, J.M.; Gago, J.A.

1986-01-01

The current capabilities at DENIM for the analysis of directly driven targets are presented. These include theoretical, computational and applied physical studies and developments of detailed simulation models for the most relevant processes in ICF. The simulation of directly driven ICF targets is carried out with the one-dimensional NORCLA code developed at DENIM. This code contains two main segments: NORMA and CLARA, able to work fully coupled and in an iterative manner. NORMA solves the hydrodynamic equations in a lagrangian mesh. It has modular programs couple to it to treat the laser or particle beam interaction with matter. Equations of state, opacities and conductivities are taken from a DENIM atomic data library, generated externally with other codes that will also be explained in this work. CLARA solves the transport equation for neutrons, as well as for charged particles, and suprathermal electrons using discrete ordinates and finite element methods in the computational procedure. Parametric calculations of multilayered single-shell targets driven by heavy ion beams are also analyzed. Finally, conclusions are focused on the ongoing developments in the areas of interest such as: radiation transport, atomic physics, particle in cell method, charged particle transport, two-dimensional calculations and instabilities. (author)

Reaching High Altitudes on Mars with an Inflatable Hypersonic Drag Balloon (Ballute)

CERN Document Server

Griebel, Hannes

2010-01-01

The concept of probing the atmosphere of planet Mars by means of a hypersonic drag balloon, a device known as a “ballute”, is a novel approach to planetary science. In this concept, the probe deploys an inflatable drag body out in space and may then enter the atmosphere either once or several times until it slowly descends towards the ground, taking continuous atmospheric and other readings across a large altitude and ground range. Hannes Griebel discusses the theory behind such a mission along with experience gained during its practical implementation, such as mission design, manufacturing, packing and deployment techniques as well as ground and flight tests. The author also studies other ballute applications, specifically emergency low Earth orbit recovery and delivering payloads to high altitude landing sites on Mars.

Studies on radiation symmetrization in heavy-ion driven hohlraum targets

International Nuclear Information System (INIS)

Temporal, M.; Atzeni, S.

1993-01-01

Radiation symmetrization within spherical, ellipsoidal and cylindral hohlraum targets for heavy ion inertial confinement fusion (ICF) is studied by means of a 3-D numerical, static model, in which realistic assumptions are made concerning the geometry of the system and, particularly, of the radiation converters. Among the systems so far studied, only spherical hohlraums with six converters achieve the illumination symmetry of the fusion capsule considered necessary for ICF applications. A parametric study of cylindrical hohlraums enlightens the effect of several parameter changes, and suggests directions for further studies, aiming at the design of two-converter targets

Power plant by deuteron beams using indirect-driven target

International Nuclear Information System (INIS)

Niu, Keishiro

1989-01-01

An indirect-driven target is proposed to be used for 6-beam nonuniform irradiation of deuteron particles. The target consists of 5 layers; tamper, radiator, smoother (radiation gap), absorber (pusher) and solid DT fuel. The fluctuation comes from nonuniform energy deposition in the radiator layer. Through the smoother layer, radiative energy transport from the radiator layer to the absorber layer is expected to smooth out the temperature fluctuation in the absorber layer. The total beam energy of 12 MJ is launched to the target by 6 beams. In order to delete the charge of the front edge of the propagating deuteron beam, the electron beam is proposed to be launched to the target with the same velocity and with the same number density at the same time of the deuteron extraction form the diode. To stabilize the beam propagation, the electron beam has a rotation velocity which induces the magnetic field in the propagation direction. The construction of the power supply system whose total stored energy is 12 MJ seems to be not difficult and to be economical. (author)

0-d energetics scaling models for Z-pinch-driven hohlraums

International Nuclear Information System (INIS)

CUNEO, MICHAEL E.; VESEY, ROGER A.; HAMMER, J.H.; PORTER, JOHN L.

2000-01-01

Wire array Z-pinches on the Z accelerator provide the most intense laboratory source of soft x-rays in the world. The unique combination of a highly-Planckian radiation source with high x-ray production efficiency (15% wall plug), large x-ray powers and energies ( >150 TW, ge1 MJ in 7 ns), large characteristic hohlraum volumes (0.5 to >10 cm 3 ), and long pulse-lengths (5 to 20 ns) may make Z-pinches a good match to the requirements for driving high-yield scale ICF capsules with adequate radiation symmetry and margin. The Z-pinch driven hohlraum approach of Hammer and Porter [Phys.Plasmas, 6, 2129(1999)] may provide a conservative and robust solution to the requirements for high yield, and is currently being studied on the Z accelerator. This paper describes a multiple region, 0-d hohlraum energetic model for Z-pinch driven hohlraums in four configurations. The authors observe consistency between the models and the measured x-ray powers and hohlraum wall temperatures to within ±20% in flux, for the four configurations

A Two-Temperature Open-Source CFD Model for Hypersonic Reacting Flows, Part Two: Multi-Dimensional Analysis †

OpenAIRE

Vincent Casseau; Daniel E. R. Espinoza; Thomas J. Scanlon; Richard E. Brown

2016-01-01

hy2Foam is a newly-coded open-source two-temperature computational fluid dynamics (CFD) solver that has previously been validated for zero-dimensional test cases. It aims at (1) giving open-source access to a state-of-the-art hypersonic CFD solver to students and researchers; and (2) providing a foundation for a future hybrid CFD-DSMC (direct simulation Monte Carlo) code within the OpenFOAM framework. This paper focuses on the multi-dimensional verification of hy2Foam and firstly describes th...

Application of a Near Infrared Imaging System for Thermographic Imaging of the Space Shuttle during Hypersonic Re-Entry

Science.gov (United States)

Zalameda, Joseph N.; Tietjen, Alan B.; Horvath, Thomas J.; Tomek, Deborah M.; Gibson, David M.; Taylor, Jeff C.; Tack, Steve; Bush, Brett C.; Mercer, C. David; Shea, Edward J.

2010-01-01

High resolution calibrated near infrared (NIR) imagery was obtained of the Space Shuttle s reentry during STS-119, STS-125, and STS-128 missions. The infrared imagery was collected using a US Navy NP-3D Orion aircraft using a long-range infrared optical package referred to as Cast Glance. The slant ranges between the Space Shuttle and Cast Glance were approximately 26-41 nautical miles at point of closest approach. The Hypersonic Thermodynamic Infrared Measurements (HYTHIRM) project was a NASA Langley led endeavor sponsored by the NASA Engineering Safety Center, the Space Shuttle Program Office and the NASA Aeronautics Research Mission Directorate to demonstrate a quantitative thermal imaging capability. HYTHIRM required several mission tools to acquire the imagery. These tools include pre-mission acquisition simulations of the Shuttle trajectory in relationship to the Cast Glance aircraft flight path, radiance modeling to predict the infrared response of the Shuttle, and post mission analysis tools to process the infrared imagery to quantitative temperature maps. The spatially resolved global thermal measurements made during the Shuttle s hypersonic reentry provides valuable flight data for reducing the uncertainty associated with present day ground-to-flight extrapolation techniques and current state-of-the-art empirical boundary-layer transition or turbulent heating prediction methods. Laminar and turbulent flight data is considered critical for the development of turbulence models supporting NASA s next-generation spacecraft. This paper will provide the motivation and details behind the use of an upgraded NIR imaging system used onboard a Navy Cast Glance aircraft and describe the characterizations and procedures performed to obtain quantitative temperature maps. A brief description and assessment will be provided of the previously used analog NIR camera along with image examples from Shuttle missions STS-121, STS-115, and solar tower test. These thermal

Computational modeling of z-pinch-driven hohlraum experiments on Z

International Nuclear Information System (INIS)

Vesey, R.A.; Porter, J.L. Jr.; Cuneo, M.E.

1999-01-01

The high-yield inertial confinement fusion concept based on a double-ended z-pinch driven hohlraum tolerates the degree of spatial inhomogeneity present in z-pinch plasma radiation sources by utilizing a relatively large hohlraum wall surface to provide spatial smoothing of the radiation delivered to the fusion capsule. The z-pinch radiation sources are separated from the capsule by radial spoke arrays. Key physics issues for this concept are the behavior of the spoke array (effect on the z-pinch performance, x-ray transmission) and the uniformity of the radiation flux incident on the surface of the capsule. Experiments are underway on the Z accelerator at Sandia National laboratories to gain understanding of these issues in a single-sided drive geometry. These experiments seek to measure the radiation coupling among the z-pinch, source hohlraum, and secondary hohlraum, as well as the uniformity of the radiation flux striking a foam witness ball diagnostic positioned in the secondary hohlraum. This paper will present the results of computational modeling of various aspects of these experiments

Mechanically-Deployed Hypersonic Decelerator and Conformal Ablator Technologies for Mars Missions

Science.gov (United States)

Venkatapathy, Ethiraj; Wercinski, Paul F.; Beck, Robin A. S.; Hamm, Kenneth R.; Yount, Bryan C.; Makino, A.; Smith, B.; Gage, P.; Prabhu, D.

2012-01-01

The concept of a mechanically deployable hypersonic decelerator, developed initially for high mass (40 MT) human Mars missions, is currently funded by OCT for technology maturation. The ADEPT (Adaptive, Deployable Entry and Placement Technology) project has broad, game-changing applicability to in situ science missions to Venus, Mars, and the Outer Planets. Combined with maturation of conformal ablator technology (another current OCT investment), the two technologies provide unique low mass mission enabling capabilities otherwise not achievable by current rigid aeroshell or by inflatables. If this abstract is accepted, we will present results that illustrate the mission enabling capabilities of the mechanically deployable architecture for: (1) robotic Mars (Discovery or New Frontiers class) in the near term; (2) alternate approaches to landing MSL-class payloads, without the need for supersonic parachute or lifting entry, in the mid-term; and (3) Heavy mass and human missions to Mars in the long term.

The cooling of confined ions driven by laser beams

International Nuclear Information System (INIS)

Reyna, L.G.

1993-01-01

We finalize the dynamics of confined ions driven by a quantized radiation field. The ions can absorb photons from an incident laser beam and relax back to the ground state by either induced emissions or spontaneous emissions. Here we assume that the absorption of photons is immediately followed by spontaneous emissions, resulting in single-level ions perturbed by the exchange of momentum with the radiation field. The probability distribution of the ions is calculated using singular expansions in the low noise asymptotic limit. The present calculations reproduce the quantum results in the limit of heavy particles in static traps, and the classical results of ions in radio-frequency confining wells

Suppression of the Rayleigh-Taylor instability due to self-radiation in a multiablation target

International Nuclear Information System (INIS)

Fujioka, Shinsuke; Sunahara, Atsushi; Nishihara, Katsunobu; Johzaki, Tomoyuki; Shiraga, Hiroyuki; Shigemori, Keisuke; Nakai, Mitsuo; Ikegawa, Tadashi; Murakami, Masakatsu; Nagai, Keiji; Norimatsu, Takayoshi; Azechi, Hiroshi; Yamanaka, Tatsuhiko; Ohnishi, Naofumi

2004-01-01

A scheme to suppress the Rayleigh-Taylor instability has been investigated for a direct-drive inertial fusion target. In a high-Z doped-plastic target, two ablation surfaces are formed separately--one driven by thermal radiation and the other driven by electron conduction. The growth of the Rayleigh-Taylor instability is significantly suppressed on the radiation-driven ablation surface inside the target due to the large ablation velocity and long density scale length. A significant reduction of the growth rate was observed in simulations and experiments using a brominated plastic target. A new direct-drive pellet was designed using this scheme

Plasma-driven liners

International Nuclear Information System (INIS)

Kilic, H.; Linhart, J.G.; Bortolotti, A.; Nardi, V.

1992-01-01

The deposition of thermal energy by laser or ion beams in an ablator is capable of producing a very large acceleration of the adjacent pusher - for power densities of 100 Terrawatts/cm 2 , ablator pressure in the range of 10 Mbar is attainable. In the case of a plasma drive such driving pressures and accelerations are not directly possible. When a snowplough (SP) is used to accelerate a thin liner, the driving pressure is that of the magnetic piston pushing the SP, i.e. at most 0.1 Mbar. However, the initial radius r 0 of the liner can be a few centimeters, instead of 1 (mm) as in the case in direct pellet implosions. In order to compete with the performance of the beam-driven liners, the plasma drive must demonstrate that a) thin liner retains a high density during the implosion (lasting a fraction of a μsec); b) radial compression ratio r 0 /r min of the order of 100 can be attained. It is also attractive to consider the staging of two or more liners in order to get sharpening and amplifications of the pressure and/or radiation pulse. If a) and b) are verified then the final pressures produced will be comparable with those of the beam-driven implosions. (author) 5 refs., 3 figs