WorldWideScience

Sample records for supersonic flight regime

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

    Science.gov (United States)

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

    2014-12-01

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

  2. Low Density Supersonic Decelerator (LDSD) Supersonic Flight Dynamics Test (SFDT) Plume Induced Environment Modelling

    Science.gov (United States)

    Mobley, B. L.; Smith, S. D.; Van Norman, J. W.; Muppidi, S.; Clark, I

    2016-01-01

    Provide plume induced heating (radiation & convection) predictions in support of the LDSD thermal design (pre-flight SFDT-1) Predict plume induced aerodynamics in support of flight dynamics, to achieve targeted freestream conditions to test supersonic deceleration technologies (post-flight SFDT-1, pre-flight SFDT-2)

  3. Payload mass improvements of supersonic retropropulsive flight for human class missions to Mars

    Science.gov (United States)

    Fagin, Maxwell H.

    Supersonic retropropulsion (SRP) is the use of retrorockets to decelerate during atmospheric flight while the vehicle is still traveling in the supersonic/hypersonic flight regime. In the context of Mars exploration, subsonic retropropulsion has a robust flight heritage for terminal landing guidance and control, but all supersonic deceleration has, to date, been performed by non-propulsive (i.e. purely aerodynamic) methods, such as aeroshells and parachutes. Extending the use of retropropulsion from the subsonic to the supersonic regime has been identified as an enabling technology for high mass humans-to-Mars architectures. However, supersonic retropropulsion still poses significant design and control challenges, stemming mainly from the complex interactions between the hypersonic engine plumes, the oncoming air flow, and the vehicle's exterior surface. These interactions lead to flow fields that are difficult to model and produce counter intuitive behaviors that are not present in purely propulsive or purely aerodynamic flight. This study will provide an overview of the work done in the design of SRP systems. Optimal throttle laws for certain trajectories will be derived that leverage aero/propulsive effects to decrease propellant requirements and increase total useful landing mass. A study of the mass savings will be made for a 10 mT reference vehicle based on a propulsive version of the Orion capsule, followed by the 100 mT ellipsoid vehicle assumed by NASA's Mars Design Reference Architecture.

  4. Flight Research and Validation Formerly Experimental Capabilities Supersonic Project

    Science.gov (United States)

    Banks, Daniel

    2009-01-01

    This slide presentation reviews the work of the Experimental Capabilities Supersonic project, that is being reorganized into Flight Research and Validation. The work of Experimental Capabilities Project in FY '09 is reviewed, and the specific centers that is assigned to do the work is given. The portfolio of the newly formed Flight Research and Validation (FRV) group is also reviewed. The various projects for FY '10 for the FRV are detailed. These projects include: Eagle Probe, Channeled Centerbody Inlet Experiment (CCIE), Supersonic Boundary layer Transition test (SBLT), Aero-elastic Test Wing-2 (ATW-2), G-V External Vision Systems (G5 XVS), Air-to-Air Schlieren (A2A), In Flight Background Oriented Schlieren (BOS), Dynamic Inertia Measurement Technique (DIM), and Advanced In-Flight IR Thermography (AIR-T).

  5. Supersonic Flight Dynamics Test 1 - Post-Flight Assessment of Simulation Performance

    Science.gov (United States)

    Dutta, Soumyo; Bowes, Angela L.; Striepe, Scott A.; Davis, Jody L.; Queen, Eric M.; Blood, Eric M.; Ivanov, Mark C.

    2015-01-01

    NASA's Low Density Supersonic Decelerator (LDSD) project conducted its first Supersonic Flight Dynamics Test (SFDT-1) on June 28, 2014. Program to Optimize Simulated Trajectories II (POST2) was one of the flight dynamics codes used to simulate and predict the flight performance and Monte Carlo analysis was used to characterize the potential flight conditions experienced by the test vehicle. This paper compares the simulation predictions with the reconstructed trajectory of SFDT-1. Additionally, off-nominal conditions seen during flight are modeled in post-flight simulations to find the primary contributors that reconcile the simulation with flight data. The results of these analyses are beneficial for the pre-flight simulation and targeting of the follow-on SFDT flights currently scheduled for summer 2015.

  6. Flight assessment of a large supersonic drone aircraft for research use

    Science.gov (United States)

    Eckstrom, C. V.; Peele, E. L.

    1974-01-01

    An assessment is made of the capabilities of the BQM-34E supersonic drone aircraft as a test bed research vehicle. This assessment is made based on a flight conducted for the purpose of obtaining flight test measurements of wing loads at various maneuver flight conditions. Flight plan preparation, flight simulation, and conduct of the flight test are discussed along with a presentation of the test data obtained and an evaluation of how closely the flight test followed the test plan.

  7. A Direct-Fire Trajectory Model for Supersonic, Transonic, and Subsonic Projectile Flight

    Science.gov (United States)

    2014-07-01

    motions of the projectile about the trajectory due to the angular motion of the projectile . For a stable projectile , these motions are typically small...A Direct-Fire Trajectory Model for Supersonic, Transonic, and Subsonic Projectile Flight by Paul Weinacht ARL-TR-6998 July 2014...Direct-Fire Trajectory Model for Supersonic, Transonic, and Subsonic Projectile Flight Paul Weinacht Weapons and Materials Research Directorate, ARL

  8. Aerodynamics characteristic of axisymmetric surface protuberance in supersonic regime

    KAUST Repository

    Qamar, Adnan

    2012-01-01

    The present work deals with the problem of an axi-symmetric surface protuberance mounted on a spherical nosed body of revolution. The numerical computations are carried out for laminar supersonic viscous flow for trapezoidal shape axi-symmetric protuberances. A free stream Mach number ranging from 3 to 8 in steps of 1 at a fixed free stream Reynolds number of 1.8x10(4) has been used in the present study. The steady solutions are obtained using a time marching approach. A newly developed Particle Velocity Upwinding (PVU) scheme has been used for the computation. The spatial flow pattern exhibits a strong bow shock in front of the hemispherical nose, which engulfs the entire base body. Near the protuberance, the fluid particle decelerates due to the adverse pressure created by the protuberance and thus the flow separates in front of the protuberance. This point of separation is found to be a function of Mach number and the protuberance shape. A low-pressure expansion region dominates the base region of the obstacle. The reattachment point for the base separation is also a function of Mach number. As the Mach number is increased the reattachment point shifts toward the protuberances base. A weak recompression shock is also seen in the base, which affects the separated zone behind the protuberance. The important design parameters such as skin friction, heat transfer, drag, and surface pressure coefficients are reported extensively.

  9. Flight tests of a supersonic natural laminar flow airfoil

    Science.gov (United States)

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

    2015-06-01

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

  10. Thermal Design and Analysis of the Supersonic Flight Dynamics Test Vehicle for the Low Density Supersonic Decelerator Project

    Science.gov (United States)

    Mastropietro, A. J.; Pauken, Michael; Sunada, Eric; Gray, Sandria

    2013-01-01

    The thermal design and analysis of the experimental Supersonic Flight Dynamics Test (SFDT) vehicle is presented. The SFDT vehicle is currently being designed as a platform to help demonstrate key technologies for NASA's Low Density Supersonic Decelerator (LDSD) project. The LDSD project is charged by NASA's Office of the Chief Technologist (OCT) with the task of advancing the state of the art in Mars Entry, Descent, and Landing (EDL) systems by developing and testing three new technologies required for landing heavier payloads on Mars. The enabling technologies under development consist of a large 33.5 meter diameter Supersonic Ringsail (SSRS) parachute and two different types of Supersonic Inflatable Aerodynamic Decelerator (SIAD) devices - a robotic class, SIAD-R, that inflates to a 6 meter diameter torus, and an exploration class, SIAD-E, that inflates to an 8 meter diameter isotensoid. As part of the technology development effort, the various elements of the new supersonic decelerator system must be tested in a Mars-like environment. This is currently planned to be accomplished by sending a series of SFDT vehicles into Earth's stratosphere. Each SFDT vehicle will be lifted to a stable float altitude by a large helium carrier balloon. Once at altitude, the SFDT vehicles will be released from their carrier balloon and spun up via spin motors to provide trajectory stability. An onboard third stage solid rocket motor will propel each test vehicle to supersonic flight in the upper atmosphere. After main engine burnout, each vehicle will be despun and testing of the deceleration system will begin: first an inflatable decelerator will be deployed around the aeroshell to increase the drag surface area, and then the large parachute will be deployed to continue the deceleration and return the vehicle back to the Earth's surface. The SFDT vehicle thermal system must passively protect the vehicle structure and its components from cold temperatures experienced during the

  11. Testing SiC fiber-reinforced ZrB2 sharp component in supersonic regime

    OpenAIRE

    Silvestroni, Laura; Monteverde, Frederic; Savino, Raffaele; SCITI, Diletta

    2012-01-01

    Ultra-high temperature ceramics are currently the most promising materials for thermal protection structures like wing leading edges in next generation space vehicles flying at hypersonic speed or/and re-entering the earth's atmosphere, which are characterized by sharp profiles to increase performances and maneuverability. In this contribution, the aero-dynamic behaviour of a very sharp ZrB2-SiC fiber composite is tested in a plasma wind tunnel in supersonic regime. A wedge with curvature rad...

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

    Science.gov (United States)

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

    2016-09-01

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

  13. Full Flight Envelope Direct Thrust Measurement on a Supersonic Aircraft

    Science.gov (United States)

    Conners, Timothy R.; Sims, Robert L.

    1998-01-01

    Direct thrust measurement using strain gages offers advantages over analytically-based thrust calculation methods. For flight test applications, the direct measurement method typically uses a simpler sensor arrangement and minimal data processing compared to analytical techniques, which normally require costly engine modeling and multisensor arrangements throughout the engine. Conversely, direct thrust measurement has historically produced less than desirable accuracy because of difficulty in mounting and calibrating the strain gages and the inability to account for secondary forces that influence the thrust reading at the engine mounts. Consequently, the strain-gage technique has normally been used for simple engine arrangements and primarily in the subsonic speed range. This paper presents the results of a strain gage-based direct thrust-measurement technique developed by the NASA Dryden Flight Research Center and successfully applied to the full flight envelope of an F-15 aircraft powered by two F100-PW-229 turbofan engines. Measurements have been obtained at quasi-steady-state operating conditions at maximum non-augmented and maximum augmented power throughout the altitude range of the vehicle and to a maximum speed of Mach 2.0 and are compared against results from two analytically-based thrust calculation methods. The strain-gage installation and calibration processes are also described.

  14. Advancing Supersonic Retropropulsion Using Mars-Relevant Flight Data: An Overview

    Science.gov (United States)

    Braun, Robert D.; Sforzo, Brandon; Campbell, Charles H.

    2017-01-01

    Advanced robotic and human missions to Mars require landed masses well in excess of current capabilities. One approach to safely land these large payloads on the Martian surface is to extend the propulsive capability currently required during subsonic descent to supersonic initiation velocities. However, until recently, no rocket engine had ever been fired into an opposing supersonic freestream. In September 2013, SpaceX performed the first supersonic retropropulsion (SRP) maneuver to decelerate the entry of the first stage of their Falcon 9 rocket. Since that flight, SpaceX has continued to perform SRP for the reentry of their vehicle first stage, having completed multiple SRP events in Mars-relevant conditions in July 2017. In FY 2014, NASA and SpaceX formed a three-year public-private partnership centered upon SRP data analysis. These activities focused on flight reconstruction, CFD analysis, a visual and infrared imagery campaign, and Mars EDL design analysis. This paper provides an overview of these activities undertaken to advance the technology readiness of Mars SRP.

  15. Investigation on in-flight particle velocity in supersonic plasma spraying

    Institute of Scientific and Technical Information of China (English)

    Li Changqing; Ma Shining; Ye Xionglin

    2005-01-01

    In-flight particle velocity and flux distribution were measured using CCD thermal spray monitor system during supersonic plasma spray processing with nano-structured Al203-TiO2 feed stocks. According to the results of particle flux measurement, the largest radian of the divergent particle stream is about 0. 2. Within the measuring range, top speed of inflight particles reached 800 m/s. Particle acceleration was accomplished within 4 cm down stream of the nozzle. Average particle velocity ( about 450 m/s) exceeded local sound speed (340 m/s) even at a mean standoff distance of 17 cm. With increasing mean standoff distance, average velocity of in-flight particle decreased according to a parabolic rule approximately.Image diagnosis showed that the result of in-flight particle velocity measurement is credible.

  16. Method and system for control of upstream flowfields of vehicle in supersonic or hypersonic atmospheric flight

    Science.gov (United States)

    Daso, Endwell O. (Inventor); Pritchett, II, Victor E. (Inventor); Wang, Ten-See (Inventor); Farr, Rebecca Ann (Inventor)

    2012-01-01

    The upstream flowfield of a vehicle traveling in supersonic or hypersonic atmospheric flight is actively controlled using attribute(s) experienced by the vehicle. Sensed attribute(s) include pressure along the vehicle's outer mold line, temperature along the vehicle's outer mold line, heat flux along the vehicle's outer mold line, and/or local acceleration response of the vehicle. A non-heated, non-plasma-producing gas is injected into an upstream flowfield of the vehicle from at least one surface location along the vehicle's outer mold line. The pressure of the gas so-injected is adjusted based on the attribute(s) so-sensed.

  17. Flight and wind-tunnel calibrations of a flush airdata sensor at high angles of attack and sideslip and at supersonic Mach numbers

    Science.gov (United States)

    Moes, Timothy R.; Whitmore, Stephen A.; Jordan, Frank L., Jr.

    1993-01-01

    A nonintrusive airdata-sensing system was calibrated in flight and wind-tunnel experiments to an angle of attack of 70 deg and to angles of sideslip of +/- 15 deg. Flight-calibration data have also been obtained to Mach 1.2. The sensor, known as the flush airdata sensor, was installed on the nosecap of an F-18 aircraft for flight tests and on a full-scale F-18 forebody for wind-tunnel tests. Flight tests occurred at the NASA Dryden Flight Research Facility, Edwards, California, using the F-18 High Alpha Research Vehicle. Wind-tunnel tests were conducted in the 30- by 60-ft wind tunnel at the NASA LaRC, Hampton, Virginia. The sensor consisted of 23 flush-mounted pressure ports arranged in concentric circles and located within 1.75 in. of the tip of the nosecap. An overdetermined mathematical model was used to relate the pressure measurements to the local airdata quantities. The mathematical model was based on potential flow over a sphere and was empirically adjusted based on flight and wind-tunnel data. For quasi-steady maneuvering, the mathematical model worked well throughout the subsonic, transonic, and low supersonic flight regimes. The model also worked well throughout the angles-of-attack and -sideslip regions studied.

  18. Investigation of estimating accuracy for aerodynamic characteristics of a scaled supersonic experimental airplane using IMU data based on flight simulation

    OpenAIRE

    1999-01-01

    This paper describes a pre-flight estimation method for aerodynamic characteristics and investigates the accuracy of the estimated aerodynamic characteristics of the scaled supersonic experimental airplane, using IMU (Inertial Measurement Unit) data obtained in a flight simulation. The results demonstrate that the required accuracy is not achieved and that the main sources of error are in the estimation of dynamic pressure, misalignment between the body axis and IMU chassis axis, and IMU disc...

  19. Flight-measured lift and drag characteristics of a large, flexible, high supersonic cruise airplane

    Science.gov (United States)

    Arnaiz, H. H.

    1977-01-01

    Flight measurements of lift, drag, and angle of attack were obtained for the XB-70 airplane, a large, flexible, high supersonic cruise airplane. This airplane had a length of over 57 meters, a takeoff gross mass of over 226,800 kilograms, and a design cruise speed of Mach 3 at an altitude of 21,340 meters. The performance measurements were made at Mach numbers from 0.72 to 3.07 and altitudes from approximately 7620 meters to 21,340 meters. The measurements were made to provide data for evaluating the techniques presently being used to design and predict the performance of aircraft in this category. Such performance characteristics as drag polars, lift-curve slopes, and maximum lift-to-drag ratios were derived from the flight data. The base drag of the airplane, changes in airplane drag with changes in engine power setting at transonic speeds, and the magnitude of the drag components of the propulsion system are also discussed.

  20. 14 CFR 25.1155 - Reverse thrust and propeller pitch settings below the flight regime.

    Science.gov (United States)

    2010-01-01

    ... 14 Aeronautics and Space 1 2010-01-01 2010-01-01 false Reverse thrust and propeller pitch settings... Powerplant Controls and Accessories § 25.1155 Reverse thrust and propeller pitch settings below the flight regime. Each control for reverse thrust and for propeller pitch settings below the flight regime must...

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

    Science.gov (United States)

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

    2011-11-01

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

  2. Preliminary performance of a vertical-attitude takeoff and landing, supersonic cruise aircraft concept having thrust vectoring integrated into the flight control system

    Science.gov (United States)

    Robins, A. W.; Beissner, F. L., Jr.; Domack, C. S.; Swanson, E. E.

    1985-01-01

    A performance study was made of a vertical attitude takeoff and landing (VATOL), supersonic cruise aircraft concept having thrust vectoring integrated into the flight control system. Those characteristics considered were aerodynamics, weight, balance, and performance. Preliminary results indicate that high levels of supersonic aerodynamic performance can be achieved. Further, with the assumption of an advanced (1985 technology readiness) low bypass ratio turbofan engine and advanced structures, excellent mission performance capability is indicated.

  3. Current Characteristics and Trends of the Tracked Satellite Population in the Human Space Flight Regime

    Science.gov (United States)

    Johnson, Nicholas L.

    2006-01-01

    Since the end of the Apollo program in 1972, human space flight has been restricted to altitudes below 600 km above the Earth s surface with most missions restricted to a ceiling below 400 km. An investigation of the tracked satellite population transiting and influencing the human space flight regime during the past 11 years (equivalent to a full solar cycle) has recently been completed. The overall effects of satellite breakups and solar activity are typically less pronounced in the human space flight regime than other regions of low Earth orbit. As of January 2006 nearly 1500 tracked objects resided in or traversed the human space flight regime, although two-thirds of these objects were in orbits of moderate to high eccentricity, significantly reducing their effect on human space flight safety. During the period investigated, the spatial density of tracked objects in the 350-400 km altitude regime of the International Space Station demonstrated a steady decline, actually decreasing by 50% by the end of the period. On the other hand, the region immediately above 600 km experienced a significant increase in its population density. This regime is important for future risk assessments, since this region represents the reservoir of debris which will influence human space flight safety in the future. The paper seeks to put into sharper perspective the risks posed to human space flight by the tracked satellite population, as well as the influences of solar activity and the effects of compliance with orbital debris mitigation guidelines on human space flight missions. Finally, the methods and successes of characterizing the population of smaller debris at human space flight regimes are addressed.

  4. Time-of-flight expansion of trapped dipolar Fermi gases: from collisionless to hydrodynamic regime

    CERN Document Server

    Veljic, Vladimir; Pelster, Axel

    2016-01-01

    A recent time-of-flight (TOF) expansion experiment with polarized fermionic erbium atoms measured a Fermi surface deformation from a sphere to an ellipsoid due to dipole-dipole interaction, thus confirming previous theoretical predictions. Here we perform a systematic study of the ground-state properties and TOF dynamics for trapped dipolar Fermi gases from the collisionless to the hydrodynamic regime at zero temperature. To this end we solve analytically the underlying Boltzmann-Vlasov equation within the relaxation-time approximation in the vicinity of equilibrium by using a suitable rescaling of the equilibrium distribution. The resulting ordinary differential equations for the respective scaling parameters are then solved numerically for experimentally realistic parameters and relaxation times that correspond to the collisionless, collisional, and hydrodynamic regime. The equations for the collisional regime are first solved in the approximation of a fixed relaxation time, and then this approach is extend...

  5. Molecular relaxation in supersonic free jets of N2 and CH4 from stimulated Raman spectroscopy and time-of-flight measurements

    OpenAIRE

    Abad, Laura; Bermejo, Dionisio; Herrero, Víctor J.; Santos, J.; Tanarro, Isabel

    1997-01-01

    The relaxation of the energy stored in the translational and rotational degrees of freedom of N2 and CH4 in the course of free jet expansions has been experimentally studied. Rotational temperatures along the expansion axis were obtained by means of stimulated Raman spectroscopy, and terminal flow velocities and translational temperatures were determined from supersonic beam time-of-flight measurements. From these measurements low-temperature cross sections for rotational relaxation have been...

  6. Supersonic free jet, molecular free regime; Fondamenti fisici dei fasci molecolari supersonici. Parte 7. Il getto libero supersonico

    Energy Technology Data Exchange (ETDEWEB)

    Sanna, G. [ENEA, Centro Ricerche Frascati, Rome (Italy). Dipt. Innovazione; Tomassetti, G. [L' Aquila Univ., L' Aquila (Italy). Dipt. di Fisica

    1999-07-01

    The structure of the free jet emitted by a converging nozzle as obtained by the method of characteristics by Ashkenas e Sherman is described in details. In particular the dependence of the field variable by the distance from the nozzle is given. The transition from continuum to molecular free regime is then considered and the sudden freeze approximation is introduced. The processing of monoatomic and polyatomic gasses is also considered. [Italian] Le caratteristiche del campo di flusso in regime continuo di un getto libero supersonico ottenute col metodo delle caratteristiche da Ashekanas e Sherman sono messe in evidenza. In paricolare le relazioni analitiche per i parametri di flusso in funzione della distanza dal nozzle sono riportate. Viene poi considerata la transizione al regime molecolare ed e' introdotta la sudden freeze approximation. Vengono anche considerate le situazioni di non equilibrio tra gradi di liberta' interni ed esterni.

  7. In-flight imaging of transverse gas jets injected into transonic and supersonic crossflows: Design and development. M.S. Thesis, Mar. 1993

    Science.gov (United States)

    Wang, Kon-Sheng Charles

    1994-01-01

    The design and development of an airborne flight-test experiment to study nonreacting gas jets injected transversely into transonic and supersonic crossflows is presented. Free-stream/crossflow Mach numbers range from 0.8 to 2.0. Planar laser-induced fluorescence (PLIF) of an iodine-seeded nitrogen jet is used to visualize the jet flow. Time-dependent images are obtained with a high-speed intensified video camera synchronized to the laser pulse rate. The entire experimental assembly is configured compactly inside a unique flight-test-fixture (FTF) mounted under the fuselage of the F-104G research aircraft, which serves as a 'flying wind tunnel' at NASA Dryden Flight Research Center. The aircraft is flown at predetermined speeds and altitudes to permit a perfectly expanded (or slightly underexpanded) gas jet to form just outside the FTF at each free-stream Mach number. Recorded gas jet images are then digitized to allow analysis of jet trajectory, spreading, and mixing characteristics. Comparisons will be made with analytical and numerical predictions. This study shows the viability of applying highly sophisticated groundbased flow diagnostic techniques to flight-test vehicle platforms that can achieve a wide range of thermo/fluid dynamic conditions. Realistic flow environments, high enthalpies, unconstrained flowfields, and moderate operating costs are also realized, in contrast to traditional wind-tunnel testing.

  8. Analysis of Photoablation Products Resulting from Polymer Materials by Supersonic Beam/Multiphoton Ionization/Time-of-Flight Mass Spectrometry.

    Science.gov (United States)

    Lin, C H; Murata, Y; Imasaka, T

    1996-04-01

    Photoablation products arising from polymer materials were examined by supersonic beam spectrometry, and the results are compared with those obtained by thermal decomposition. The high selectivity provided by supersonic beam spectrometry allows detection of minor species, e.g., styrene occurred from poly(α-methylstyrene) by cleavage of a methyl group and by proton rearrangement. Because ablation techniques involve high temperatures, thermally stable materials such as poly(p-methylstyrene) can be examined. The latter material is difficult to examine by thermal decomposition, even at 350 °C. It is also possible to differentiate between isomer ablation products, e.g., α-methylstyrene and p-methylstyrene. The instrumental setup described herein was used to examine several authentic samples, such as ABS resin (acrylonitrile-butadiene-styrene) and O-ring (SBR, styrene-butadiene rubber), as well as polystyrene foam. As a result, a styrene segment could be confirmed to be present in these materials. However, no evidence was found for its presence in a glue sample that was suspected to contain styrene on the basis of conventional mass spectrometry. The latter finding confirms the high degree of selectivity of the technique.

  9. Silent and Efficient Supersonic Bi-Directional Flying Wing Project

    Data.gov (United States)

    National Aeronautics and Space Administration — We propose a Phase I study for a novel concept of a supersonic bi-directional (SBiDir) flying wing (FW) that has the potential to revolutionize supersonic flight...

  10. Method and System for Weakening Shock Wave Strength at Leading Edge Surfaces of Vehicle in Supersonic Atmospheric Flight

    Science.gov (United States)

    Daso, Endwell O. (Inventor); Pritchett, Victor E., II (Inventor); Wang, Ten-See (Inventor); Farr, Rebecca Ann (Inventor); Auslender, Aaron Howard (Inventor); Blankson, Isaiah M. (Inventor); Plotkin, Kenneth J. (Inventor)

    2015-01-01

    A method and system are provided to weaken shock wave strength at leading edge surfaces of a vehicle in atmospheric flight. One or more flight-related attribute sensed along a vehicle's outer mold line are used to control the injection of a non-heated, non-plasma-producing gas into a local external flowfield of the vehicle from at least one leading-edge surface location along the vehicle's outer mold line. Pressure and/or mass flow rate of the gas so-injected is adjusted in order to cause a Rankine-Hugoniot Jump Condition along the vehicle's outer mold line to be violated.

  11. X-33 Attitude Control System Design for Ascent, Transition, and Entry Flight Regimes

    Science.gov (United States)

    Hall, Charles E.; Gallaher, Michael W.; Hendrix, Neal D.

    1998-01-01

    The Vehicle Control Systems Team at Marshall Space Flight Center, Systems Dynamics Laboratory, Guidance and Control Systems Division is designing under a cooperative agreement with Lockheed Martin Skunkworks, the Ascent, Transition, and Entry flight attitude control system for the X-33 experimental vehicle. Ascent flight control begins at liftoff and ends at linear aerospike main engine cutoff (NECO) while Transition and Entry flight control begins at MECO and concludes at the terminal area energy management (TAEM) interface. TAEM occurs at approximately Mach 3.0. This task includes not only the design of the vehicle attitude control systems but also the development of requirements for attitude control system components and subsystems. The X-33 attitude control system design is challenged by a short design cycle, the design environment (Mach 0 to about Mach 15), and the X-33 incremental test philosophy. The X-33 design-to-launch cycle of less than 3 years requires a concurrent design approach while the test philosophy requires design adaptation to vehicle variations that are a function of Mach number and mission profile. The flight attitude control system must deal with the mixing of aerosurfaces, reaction control thrusters, and linear aerospike engine control effectors and handle parasitic effects such as vehicle flexibility and propellant sloshing from the uniquely shaped propellant tanks. The attitude control system design is, as usual, closely linked to many other subsystems and must deal with constraints and requirements from these subsystems.

  12. Wind-tunnel/flight correlation study of aerodynamic characteristics of a large flexible supersonic cruise airplane (XB-70-1). 3: A comparison between characteristics predicted from wind-tunnel measurements and those measured in flight

    Science.gov (United States)

    Arnaiz, H. H.; Peterson, J. B., Jr.; Daugherty, J. C.

    1980-01-01

    A program was undertaken by NASA to evaluate the accuracy of a method for predicting the aerodynamic characteristics of large supersonic cruise airplanes. This program compared predicted and flight-measured lift, drag, angle of attack, and control surface deflection for the XB-70-1 airplane for 14 flight conditions with a Mach number range from 0.76 to 2.56. The predictions were derived from the wind-tunnel test data of a 0.03-scale model of the XB-70-1 airplane fabricated to represent the aeroelastically deformed shape at a 2.5 Mach number cruise condition. Corrections for shape variations at the other Mach numbers were included in the prediction. For most cases, differences between predicted and measured values were within the accuracy of the comparison. However, there were significant differences at transonic Mach numbers. At a Mach number of 1.06 differences were as large as 27 percent in the drag coefficients and 20 deg in the elevator deflections. A brief analysis indicated that a significant part of the difference between drag coefficients was due to the incorrect prediction of the control surface deflection required to trim the airplane.

  13. Analytical and computational investigations of a magnetohydrodynamics (MHD) energy-bypass system for supersonic gas turbine engines to enable hypersonic flight

    Science.gov (United States)

    Benyo, Theresa Louise

    Historically, the National Aeronautics and Space Administration (NASA) has used rocket-powered vehicles as launch vehicles for access to space. A familiar example is the Space Shuttle launch system. These vehicles carry both fuel and oxidizer onboard. If an external oxidizer (such as the Earth's atmosphere) is utilized, the need to carry an onboard oxidizer is eliminated, and future launch vehicles could carry a larger payload into orbit at a fraction of the total fuel expenditure. For this reason, NASA is currently researching the use of air-breathing engines to power the first stage of two-stage-to-orbit hypersonic launch systems. Removing the need to carry an onboard oxidizer leads also to reductions in total vehicle weight at liftoff. This in turn reduces the total mass of propellant required, and thus decreases the cost of carrying a specific payload into orbit or beyond. However, achieving hypersonic flight with air-breathing jet engines has several technical challenges. These challenges, such as the mode transition from supersonic to hypersonic engine operation, are under study in NASA's Fundamental Aeronautics Program. One propulsion concept that is being explored is a magnetohydrodynamic (MHD) energy- bypass generator coupled with an off-the-shelf turbojet/turbofan. It is anticipated that this engine will be capable of operation from takeoff to Mach 7 in a single flowpath without mode transition. The MHD energy bypass consists of an MHD generator placed directly upstream of the engine, and converts a portion of the enthalpy of the inlet flow through the engine into electrical current. This reduction in flow enthalpy corresponds to a reduced Mach number at the turbojet inlet so that the engine stays within its design constraints. Furthermore, the generated electrical current may then be used to power aircraft systems or an MHD accelerator positioned downstream of the turbojet. The MHD accelerator operates in reverse of the MHD generator, re-accelerating the

  14. The Edge supersonic transport

    Science.gov (United States)

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

    1992-01-01

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

  15. Supersonic compressor

    Science.gov (United States)

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

    2016-04-12

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

  16. Two lighter than air systems in opposing flight regimes: An unmanned short haul, heavy load transport balloon and a manned, light payload airship

    Science.gov (United States)

    Pohl, R. A.

    1975-01-01

    Lighter Than Air vehicles are generally defined or categorized by the shape of the balloon, payload capacity and operational flight regime. Two balloon systems that are classed as being in opposite categories are described. One is a cable guided, helium filled, short haul, heavy load transport Lighter Than Air system with a natural shaped envelope. The other is a manned, aerodynamic shaped airship which utilizes hot air as the buoyancy medium and is in the light payload class. While the airship is in the design/fabrication phase with flight tests scheduled for the latter part of 1974, the transport balloon system has been operational for some eight years.

  17. Computational study of collisions between O(3P) and NO(2Π) at temperatures relevant to the hypersonic flight regime.

    Science.gov (United States)

    Castro-Palacio, Juan Carlos; Nagy, Tibor; Bemish, Raymond J; Meuwly, Markus

    2014-10-28

    Reactions involving N and O atoms dominate the energetics of the reactive air flow around spacecraft when reentering the atmosphere in the hypersonic flight regime. For this reason, the thermal rate coefficients for reactive processes involving O((3)P) and NO((2)Π) are relevant over a wide range of temperatures. For this purpose, a potential energy surface (PES) for the ground state of the NO2 molecule is constructed based on high-level ab initio calculations. These ab initio energies are represented using the reproducible kernel Hilbert space method and Legendre polynomials. The global PES of NO2 in the ground state is constructed by smoothly connecting the surfaces of the grids of various channels around the equilibrium NO2 geometry by a distance-dependent weighting function. The rate coefficients were calculated using Monte Carlo integration. The results indicate that at high temperatures only the lowest A-symmetry PES is relevant. At the highest temperatures investigated (20,000 K), the rate coefficient for the "O1O2+N" channel becomes comparable (to within a factor of around three) to the rate coefficient of the oxygen exchange reaction. A state resolved analysis shows that the smaller the vibrational quantum number of NO in the reactants, the higher the relative translational energy required to open it and conversely with higher vibrational quantum number, less translational energy is required. This is in accordance with Polanyi's rules. However, the oxygen exchange channel (NO2+O1) is accessible at any collision energy. Finally, this work introduces an efficient computational protocol for the investigation of three-atom collisions in general.

  18. The Effect of Magnetohydrodynamic (MHD) Energy Bypass on Specific Thrust for a Supersonic Turbojet Engine

    Science.gov (United States)

    Benyo, Theresa L.

    2010-01-01

    This paper describes the preliminary results of a thermodynamic cycle analysis of a supersonic turbojet engine with a magnetohydrodynamic (MHD) energy bypass system that explores a wide range of MHD enthalpy extraction parameters. Through the analysis described here, it is shown that applying a magnetic field to a flow path in the Mach 2.0 to 3.5 range can increase the specific thrust of the turbojet engine up to as much as 420 N/(kg/s) provided that the magnitude of the magnetic field is in the range of 1 to 5 Tesla. The MHD energy bypass can also increase the operating Mach number range for a supersonic turbojet engine into the hypersonic flight regime. In this case, the Mach number range is shown to be extended to Mach 7.0.

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

    Data.gov (United States)

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

  20. Findings from the Supersonic Qualification Program of the Mars Science Laboratory Parachute System

    Science.gov (United States)

    Sengupta, Anita; Steltzner, Adam; Witkowski, Allen; Candler, Graham; Pantano, Carlos

    2009-01-01

    In 2012, the Mars Science Laboratory Mission (MSL) will deploy NASA's largest extra-terrestrial parachute, a technology integral to the safe landing of its advanced robotic explorer on the surface. The supersonic parachute system is a mortar deployed 21.5 m disk-gap-band (DGB) parachute, identical in geometric scaling to the Viking era DGB parachutes of the 1970's. The MSL parachute deployment conditions are Mach 2.3 at a dynamic pressure of 750 Pa. The Viking Balloon Launched Decelerator Test (BLDT) successfully demonstrated a maximum of 700 Pa at Mach 2.2 for a 16.1 m DGB parachute in its AV4 flight. All previous Mars deployments have derived their supersonic qualification from the Viking BLDT test series, preventing the need for full scale high altitude supersonic testing. The qualification programs for Mars Pathfinder, Mars Exploration Rover, and Phoenix Scout Missions were all limited to subsonic structural qualification, with supersonic performance and survivability bounded by the BLDT qualification. The MSL parachute, at the edge of the supersonic heritage deployment space and 33% larger than the Viking parachute, accepts a certain degree of risk without addressing the supersonic environment in which it will deploy. In addition, MSL will spend up to 10 seconds above Mach 1.5, an aerodynamic regime that is associated with a known parachute instability characterized by significant canopy projected area fluctuation and dynamic drag variation. This aerodynamic instability, referred to as "area oscillations" by the parachute community has drag performance, inflation stability, and structural implications, introducing risk to mission success if not quantified for the MSL parachute system. To minimize this risk and as an alternative to a prohibitively expensive high altitude test program, a multi-phase qualification program using computation simulation validated by subscale test was developed and implemented for MSL. The first phase consisted of 2% of fullscale

  1. Flight Test Results from the Rake Airflow Gage Experiment on the F-15B

    Science.gov (United States)

    Frederick, Michael; Ratnayake, Nalin

    2011-01-01

    The results are described of the Rake Airflow Gage Experiment (RAGE), which was designed and fabricated to support the flight test of a new supersonic inlet design using Dryden's Propulsion Flight Test Fixture (PFTF) and F-15B testbed airplane (see figure). The PFTF is a unique pylon that was developed for flight-testing propulsion-related experiments such as inlets, nozzles, and combustors over a range of subsonic and supersonic flight conditions. The objective of the RAGE program was to quantify the local flowfield at the aerodynamic interface plane of the Channeled Centerbody Inlet Experiment (CCIE). The CCIE is a fixed representation of a conceptual mixed-compression supersonic inlet with a translating biconic centerbody. The primary goal of RAGE was to identify the relationship between free-stream and local Mach number in the low supersonic regime, with emphasis on the identification of the particular free-stream Mach number that produced a local Mach number of 1.5. Measurements of the local flow angularity, total pressure distortion, and dynamic pressure over the interface plane were also desired. The experimental data for the RAGE program were obtained during two separate research flights. During both flights, local flowfield data were obtained during straight and level acceleration segments out to steady-state test points. The data obtained from the two flights showed small variations in Mach number, flow angularity, and dynamic pressure across the interface plane at all flight conditions. The data show that a free-stream Mach number of 1.65 will produce the desired local Mach number of 1.5 for CCIE. The local total pressure distortion over the interface plane at this condition was approximately 1.5%. At this condition, there was an average of nearly 2 of downwash over the interface plane. This small amount of downwash is not expected to adversely affect the performance of the CCIE inlet.

  2. On supersonic combustion

    Institute of Scientific and Technical Information of China (English)

    袁生学

    1999-01-01

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

  3. Final Report for the Advanced Concept Studies for Supersonic Commercial Transports Entering Service in the 2030 to 2035 Period, N+3 Supersonic Program

    Science.gov (United States)

    Morgenstern, John; Norstrud, Nicole; Stelmack, Marc; Skoch, Craig

    2010-01-01

    The N+3 Final Report documents the work and progress made by Lockheed Martin Aeronautics in response to the NASA sponsored program "N+3 NRA Advanced Concept Studies for Supersonic Commercial Transports Entering Service in the 2030 to 2035 Period." The key technical objective of this effort was to generate promising supersonic concepts for the 2030 to 2035 timeframe and to develop plans for maturing the technologies required to make those concepts a reality. The N+3 program is aligned with NASA's Supersonic Project and is focused on providing alternative system-level solutions capable of overcoming the efficiency, environmental, and performance barriers to practical supersonic flight

  4. Supersonic unstalled flutter

    Science.gov (United States)

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

    1978-01-01

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

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

    Science.gov (United States)

    Townsend, J. C.

    1976-01-01

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

  6. Supersonic Injection of Aerated Liquid Jet

    Science.gov (United States)

    Choudhari, Abhijit; Sallam, Khaled

    2016-11-01

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

  7. Entropy Minimization Design Approach of Supersonic Internal Passages

    Directory of Open Access Journals (Sweden)

    Jorge Sousa

    2015-08-01

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

  8. Flying qualities design criteria applicable to supersonic cruise aircraft

    Science.gov (United States)

    Chalk, C. R.

    1980-01-01

    A comprehensive set of flying qualities design criteria was prepared for use in the supersonic cruise research program. The framework for stating the design criteria is established and design criteria are included which address specific failures, approach to dangerous flight conditions, flight at high angle of attack, longitudinal and lateral directional stability and control, the primary flight control system, and secondary flight controls. Examples are given of lateral directional design criteria limiting lateral accelerations at the cockpit, time to roll through 30 deg of bank, and time delay in the pilot's command path. Flight test data from the Concorde certification program are used to substantiate a number of the proposed design criteria.

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

    Science.gov (United States)

    Timofeev, Ivan; Aniskin, Vladimir; Mironov, Sergey

    2016-10-01

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

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

    Science.gov (United States)

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

    2015-05-01

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

  11. Computational Fluid Dynamics Modeling of a Supersonic Nozzle and Integration into a Variable Cycle Engine Model

    Science.gov (United States)

    Connolly, Joseph W.; Friedlander, David; Kopasakis, George

    2015-01-01

    This paper covers the development of an integrated nonlinear dynamic simulation for a variable cycle turbofan engine and nozzle that can be integrated with an overall vehicle Aero-Propulso-Servo-Elastic (APSE) model. A previously developed variable cycle turbofan engine model is used for this study and is enhanced here to include variable guide vanes allowing for operation across the supersonic flight regime. The primary focus of this study is to improve the fidelity of the model's thrust response by replacing the simple choked flow equation convergent-divergent nozzle model with a MacCormack method based quasi-1D model. The dynamic response of the nozzle model using the MacCormack method is verified by comparing it against a model of the nozzle using the conservation element/solution element method. A methodology is also presented for the integration of the MacCormack nozzle model with the variable cycle engine.

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

    Data.gov (United States)

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

  13. Computational study of collisions between O({sup 3}P) and NO({sup 2}Π) at temperatures relevant to the hypersonic flight regime

    Energy Technology Data Exchange (ETDEWEB)

    Castro-Palacio, Juan Carlos; Nagy, Tibor; Meuwly, Markus, E-mail: m.meuwly@unibas.ch [Department of Chemistry, University of Basel, Klingelbergstrasse 80, CH-4056 Basel (Switzerland); Bemish, Raymond J. [Air Force Research Laboratory, Space Vehicles Directorate, Kirtland AFB, New Mexico 87117 (United States)

    2014-10-28

    Reactions involving N and O atoms dominate the energetics of the reactive air flow around spacecraft when reentering the atmosphere in the hypersonic flight regime. For this reason, the thermal rate coefficients for reactive processes involving O({sup 3}P) and NO({sup 2}Π) are relevant over a wide range of temperatures. For this purpose, a potential energy surface (PES) for the ground state of the NO{sub 2} molecule is constructed based on high-level ab initio calculations. These ab initio energies are represented using the reproducible kernel Hilbert space method and Legendre polynomials. The global PES of NO{sub 2} in the ground state is constructed by smoothly connecting the surfaces of the grids of various channels around the equilibrium NO{sub 2} geometry by a distance-dependent weighting function. The rate coefficients were calculated using Monte Carlo integration. The results indicate that at high temperatures only the lowest A-symmetry PES is relevant. At the highest temperatures investigated (20 000 K), the rate coefficient for the “O1O2+N” channel becomes comparable (to within a factor of around three) to the rate coefficient of the oxygen exchange reaction. A state resolved analysis shows that the smaller the vibrational quantum number of NO in the reactants, the higher the relative translational energy required to open it and conversely with higher vibrational quantum number, less translational energy is required. This is in accordance with Polanyi's rules. However, the oxygen exchange channel (NO2+O1) is accessible at any collision energy. Finally, this work introduces an efficient computational protocol for the investigation of three-atom collisions in general.

  14. Supersonic flows over cavities

    Institute of Scientific and Technical Information of China (English)

    Tianwen FANG; Meng DING; Jin ZHOU

    2008-01-01

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

  15. Review and prospect of supersonic business jet design

    Science.gov (United States)

    Sun, Yicheng; Smith, Howard

    2017-04-01

    This paper reviews the environmental issues and challenges appropriate to the design of supersonic business jets (SSBJs). There has been a renewed, worldwide interest in developing an environmentally friendly, economically viable and technologically feasible supersonic transport aircraft. A historical overview indicates that the SSBJ will be the pioneer for the next generation of supersonic airliners. As a high-end product itself, the SSBJ will likely take a market share in the future. The mission profile appropriate to this vehicle is explored considering the rigorous environmental constraints. Mitigation of the sonic boom and improvements aerodynamic efficiency in flight are the most challenging features of civil supersonic transport. Technical issues and challenges associated with this type of aircraft are identified, and methodologies for the SSBJ design are discussed. Due to the tightly coupled issues, a multidisciplinary design, analysis and optimization environment is regarded as the essential approach to the creation of a low-boom low-drag supersonic aircraft. Industrial and academic organizations have an interest in this type of vehicle are presented. Their investments in SSBJ design will hopefully get civil supersonic transport back soon.

  16. Infinitesimal Conical Supersonic Flow

    Science.gov (United States)

    Busemann, Adolf

    1947-01-01

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

  17. Aerodynamic Models for the Low Density Supersonic Decelerator (LDSD) Test Vehicles

    Science.gov (United States)

    Van Norman, John W.; Dyakonov, Artem; Schoenenberger, Mark; Davis, Jody; Muppidi, Suman; Tang, Chun; Bose, Deepak; Mobley, Brandon; Clark, Ian

    2016-01-01

    An overview of aerodynamic models for the Low Density Supersonic Decelerator (LDSD) Supersonic Flight Dynamics Test (SFDT) campaign test vehicle is presented, with comparisons to reconstructed flight data and discussion of model updates. The SFDT campaign objective is to test Supersonic Inflatable Aerodynamic Decelerator (SIAD) and large supersonic parachute technologies at high altitude Earth conditions relevant to entry, descent, and landing (EDL) at Mars. Nominal SIAD test conditions are attained by lifting a test vehicle (TV) to 36 km altitude with a helium balloon, then accelerating the TV to Mach 4 and 53 km altitude with a solid rocket motor. Test flights conducted in June of 2014 (SFDT-1) and 2015 (SFDT-2) each successfully delivered a 6 meter diameter decelerator (SIAD-R) to test conditions and several seconds of flight, and were successful in demonstrating the SFDT flight system concept and SIAD-R technology. Aerodynamic models and uncertainties developed for the SFDT campaign are presented, including the methods used to generate them and their implementation within an aerodynamic database (ADB) routine for flight simulations. Pre- and post-flight aerodynamic models are compared against reconstructed flight data and model changes based upon knowledge gained from the flights are discussed. The pre-flight powered phase model is shown to have a significant contribution to off-nominal SFDT trajectory lofting, while coast and SIAD phase models behaved much as predicted.

  18. Terminal area energy management regime investigations utilizing an 0.030-scale model (47-0) of the space shuttle vehicle orbiter configuration 140A/B/C/R in the Ames Research Center 11 x 11 foot transonic wind tunnel (OA148), volume 5

    Science.gov (United States)

    Hawthorne, P. J.

    1976-01-01

    Data obtained in wind tunnel test OA148 are presented. The objectives of the test series were to: (1) obtain pressure distributions, forces and moments over the vehicle 5 orbiter in the thermal area energy management (TAEM) and approach phases of flight; (2) obtain elevon and rudder hinge moments in the TAEM and approach phases of flight; (3) obtain body flap and elevon loads for verification of loads balancing with integrated pressure distributions; and (4) obtain pressure distributions near the short OMS pods in the high subsonic, transonic and low supersonic Mach number regimes.

  19. Continuous supersonic plasma wind tunnel

    DEFF Research Database (Denmark)

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

    1968-01-01

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

  20. Continuous supersonic plasma wind tunnel

    DEFF Research Database (Denmark)

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

    1969-01-01

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

  1. A Preliminary Evaluation of Supersonic Transport Category Vehicle Operations in the National Airspace System

    Science.gov (United States)

    Underwood, Matthew C.; Guminsky, Michael D.

    2015-01-01

    Several public sector businesses and government agencies, including the National Aeronautics and Space Administration are currently working on solving key technological barriers that must be overcome in order to realize the vision of low-boom supersonic flights conducted over land. However, once these challenges are met, the manner in which this class of aircraft is integrated in the National Airspace System may become a potential constraint due to the significant environmental, efficiency, and economic repercussions that their integration may cause. Background research was performed on historic supersonic operations in the National Airspace System, including both flight deck procedures and air traffic controller procedures. Using this information, an experiment was created to test some of these historic procedures in a current-day, emerging Next Generation Air Transportation System (NextGen) environment and observe the interactions between commercial supersonic transport aircraft and modern-day air traffic. Data was gathered through batch simulations of supersonic commercial transport category aircraft operating in present-day traffic scenarios as a base-lining study to identify the magnitude of the integration problems and begin the exploration of new air traffic management technologies and architectures which will be needed to seamlessly integrate subsonic and supersonic transport aircraft operations. The data gathered include information about encounters between subsonic and supersonic aircraft that may occur when supersonic commercial transport aircraft are integrated into the National Airspace System, as well as flight time data. This initial investigation is being used to inform the creation and refinement of a preliminary Concept of Operations and for the subsequent development of technologies that will enable overland supersonic flight.

  2. Advanced Concept Studies for Supersonic Commercial Transports Entering Service in the 2018 to 2020 Period

    Science.gov (United States)

    Morgenstern, John; Norstrud, Nicole; Sokhey, Jack; Martens, Steve; Alonso, Juan J.

    2013-01-01

    Lockheed Martin Aeronautics Company (LM), working in conjunction with General Electric Global Research (GE GR), Rolls-Royce Liberty Works (RRLW), and Stanford University, herein presents results from the "N+2 Supersonic Validations" contract s initial 22 month phase, addressing the NASA solicitation "Advanced Concept Studies for Supersonic Commercial Transports Entering Service in the 2018 to 2020 Period." This report version adds documentation of an additional three month low boom test task. The key technical objective of this effort was to validate integrated airframe and propulsion technologies and design methodologies. These capabilities aspired to produce a viable supersonic vehicle design with environmental and performance characteristics. Supersonic testing of both airframe and propulsion technologies (including LM3: 97-023 low boom testing and April-June nozzle acoustic testing) verified LM s supersonic low-boom design methodologies and both GE and RRLW's nozzle technologies for future implementation. The N+2 program is aligned with NASA s Supersonic Project and is focused on providing system-level solutions capable of overcoming the environmental and performance/efficiency barriers to practical supersonic flight. NASA proposed "Initial Environmental Targets and Performance Goals for Future Supersonic Civil Aircraft". The LM N+2 studies are built upon LM s prior N+3 100 passenger design studies. The LM N+2 program addresses low boom design and methodology validations with wind tunnel testing, performance and efficiency goals with system level analysis, and low noise validations with two nozzle (GE and RRLW) acoustic tests.

  3. Mixing in Supersonic Turbulence

    CERN Document Server

    Pan, Liubin

    2010-01-01

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

  4. Macroeconomic regimes

    NARCIS (Netherlands)

    Baele, L.T.M.; Bekaert, G.R.J.; Cho, S.; Inghelbrecht, K.; Moreno, A.

    2015-01-01

    A New-Keynesian macro-model is estimated accommodating regime-switching behavior in monetary policy and macro-shocks. A key to our estimation strategy is the use of survey-based expectations for inflation and output. Output and inflation shocks shift to the low volatility regime around 1985 and 1990

  5. Supersonic induction plasma jet modeling

    Energy Technology Data Exchange (ETDEWEB)

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

    2001-06-01

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

  6. Flight and analytical investigations of a structural mode excitation system on the YF-12A airplane

    Science.gov (United States)

    Goforth, E. A.; Murphy, R. C.; Beranek, J. A.; Davis, R. A.

    1987-01-01

    A structural excitation system, using an oscillating canard vane to generate force, was mounted on the forebody of the YF-12A airplane. The canard vane was used to excite the airframe structural modes during flight in the subsonic, transonic, and supersonic regimes. Structural modal responses generated by the canard vane forces were measured at the flight test conditions by airframe-mounted accelerometers. Correlations of analytical and experimental aeroelastic results were made. Doublet lattice, steady state double lattice with uniform lag, Mach box, and piston theory all produced acceptable analytical aerodynamic results within the restrictions that apply to each. In general, the aerodynamic theory methods, carefully applied, were found to predict the dynamic behavior of the YF-12A aircraft adequately.

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

    Science.gov (United States)

    Vishwakarma, Manmohan; Vaidyanathan, Aravind

    2016-01-01

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

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

    Science.gov (United States)

    Fischer, Michael C.

    1992-01-01

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

  9. Tesseract supersonic business transport

    Science.gov (United States)

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

    1992-01-01

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

  10. Tesseract: Supersonic business transport

    Science.gov (United States)

    Reshotko, Eli; Garbinski, Gary

    1992-01-01

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

  11. Base pressure and heat transfer tests of the 0.0225-scale space shuttle plume simulation model (19-OTS) in yawed flight conditions in the NASA-Lewis 10x10-foot supersonic wind tunnel (test IH83)

    Science.gov (United States)

    Foust, J. W.

    1979-01-01

    Wind tunnel tests were performed to determine pressures, heat transfer rates, and gas recovery temperatures in the base region of a rocket firing model of the space shuttle integrated vehicle during simulated yawed flight conditions. First and second stage flight of the space shuttle were simulated by firing the main engines in conjunction with the SRB rocket motors or only the SSME's into the continuous tunnel airstream. For the correct rocket plume environment, the simulated altitude pressures were halved to maintain the rocket chamber/altitude pressure ratio. Tunnel freestream Mach numbers from 2.2 to 3.5 were simulated over an altitude range of 60 to 130 thousand feet with varying angle of attack, yaw angle, nozzle gimbal angle and SRB chamber pressure. Gas recovery temperature data derived from nine gas temperature probe runs are presented. The model configuration, instrumentation, test procedures, and data reduction are described.

  12. Supersonic flow past a flat lattice of cylindrical rods

    Science.gov (United States)

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

    2016-06-01

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

  13. Effect of Microjet Injection on Supersonic Jet Noise

    Science.gov (United States)

    Zaman, K. B. M. Q.; Podboy, G. G.

    2010-01-01

    The effect of microjet (jet) injection on the noise from supersonic jets is investigated. Three convergent-divergent (C-D) nozzles and one convergent nozzle, all having the same exit diameters, are used in the study. The jets are injected perpendicular to the primary jet close to the nozzle lip from six equally-spaced ports having a jet-to-primary-jet diameter ratio of 0.0054. Effects in the over-expanded, fully expanded as well as underexpanded flow regimes are explored. Relative to the effect on subsonic jets, larger reductions in the overall sound pressure level (OASPL) are achieved in most supersonic conditions. The largest reductions are typically associated with suppression of screech and transonic tones. For a shock-free, fully expanded case, the OASPL reductions achieved are comparable to that in the subsonic case; the same correlation, found for subsonic jet noise reduction at shallow observation angle, applies.

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

    NARCIS (Netherlands)

    Sun, Z.

    2014-01-01

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

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

    Science.gov (United States)

    Bulat, Pavel V.; Volkov, Konstantin N.

    2016-01-01

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

  16. Supersonic Dislocation Bursts in Silicon

    Science.gov (United States)

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

    2016-06-01

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

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

    Science.gov (United States)

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

    2016-10-01

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

  18. Properties of Supersonic Evershed Downflows

    Science.gov (United States)

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

    2016-12-01

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

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

    Science.gov (United States)

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

    2016-06-01

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

  20. Ongoing Validation of Computational Fluid Dynamics for Supersonic Retro-Propulsion

    Science.gov (United States)

    Schauerhamer, Guy; Trumble, Kerry; Carlson, Jan-Renee; Edquist, Karl; Buning, Pieter; Sozer, Emre

    2011-01-01

    During the Entry, Decent, and Landing phase of planetary exploration, previous methods of deceleration do not scale with high mass spacecraft. Supersonic Retro-Propulsion(SRP)is a viable method to decelerate large spacecraft including those that will carry humans to Mars. Flow data at these conditions are difficult to obtain through flight or wind tunnel experiments

  1. Supersonic Wing Optimization Using SpaRibs

    Science.gov (United States)

    Locatelli, David; Mulani, Sameer B.; Liu, Qiang; Tamijani, Ali Y.; Kapania, Rakesh K.

    2014-01-01

    This research investigates the advantages of using curvilinear spars and ribs, termed SpaRibs, to design a supersonic aircraft wing-box in comparison to the use of classic design concepts that employ straight spars and ribs. The objective is to achieve a more efficient load-bearing mechanism and to passively control the deformation of the structure under the flight loads. Moreover, the use of SpaRibs broadens the design space and allows for natural frequencies and natural mode shape tailoring. The SpaRibs concept is implemented in a new optimization MATLAB-based framework referred to as EBF3SSWingOpt. This optimization scheme performs both the sizing and the shaping of the internal structural elements, connecting the optimizer with the analysis software. The shape of the SpaRibs is parametrically defined using the so called Linked Shape method. Each set of SpaRibs is placed in a one by one square domain of the natural space. The set of curves is subsequently transformed in the physical space for creating the wing structure geometry layout. The shape of each curve of each set is unique; however, mathematical relations link the curvature in an effort to reduce the number of design variables. The internal structure of a High Speed Commercial Transport aircraft concept developed by Boeing is optimized subjected to stress, subsonic flutter and supersonic flutter constraints. The results show that the use of the SpaRibs allows for the reduction of the aircraft's primary structure weight without violating the constraints. A weight reduction of about 15 percent is observed.

  2. Properties of Supersonic Evershed Downflows

    CERN Document Server

    Pozuelo, Sara Esteban; Rodriguez, Jaime de la Cruz

    2016-01-01

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

  3. In-flight investigation of a rotating cylinder-based structural excitation system for flutter testing

    Science.gov (United States)

    Vernon, Lura

    1993-01-01

    A research excitation system was test flown at the NASA Dryden Flight Research Facility on the two-seat F-16XL aircraft. The excitation system is a wingtip-mounted vane with a rotating slotted cylinder at the trailing edge. As the cylinder rotates during flight, the flow is alternately deflected upward and downward through the slot, resulting in a periodic lift force at twice the cylinder's rotational frequency. Flight testing was conducted to determine the excitation system's effectiveness in the subsonic, transonic, and supersonic flight regimes. Primary research objectives were to determine the system's ability to develop adequate force levels to excite the aircraft's structure and to determine the frequency range over which the system could excite structural modes of the aircraft. In addition, studies were conducted to determine optimal excitation parameters, such as sweep duration, sweep type, and energy levels. The results from the exciter were compared with results from atmospheric turbulence excitation at the same flight conditions. The comparison indicated that the vane with a rotating slotted cylinder provides superior results. The results from the forced excitation were of higher quality and had less variation than the results from atmospheric turbulence. The forced excitation data also invariably yielded higher structural damping values than those from the atmospheric turbulence data.

  4. Mixing of Supersonic Streams

    Science.gov (United States)

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

    1998-01-01

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

  5. Regimes internacionais

    OpenAIRE

    Meireles, André Bezerra

    2004-01-01

    Dissertação (mestraddo) - Universidade Federal de Santa Catarina, Centro de Ciências Jurídicas. Programa de Pós-Graduação em Direito. Qual o papel dos regimes internacionais com relação ao comportamento dos agentes das relações internacionais contemporâneas, em especial, o Estado? Dentro das negociações de uma esfera internacional caracterizada por uma forte interdependência econômica, verificada a existência de múltiplos canais de conexões entre as sociedades, e uma tendência contínua p...

  6. Supersonic Plasma Flow Control Experiments

    Science.gov (United States)

    2005-12-01

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

  7. Supersonic Chordwise Bending Flutter in Cascades

    Science.gov (United States)

    1975-05-31

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

  8. Supersonic flow imaging via nanoparticles

    Institute of Scientific and Technical Information of China (English)

    2009-01-01

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

  9. Development of semi-free jet test facility for supersonic engine; Choonsoku engine shiken shisetsu semi free jet shiken sochi no kaihatsu

    Energy Technology Data Exchange (ETDEWEB)

    Kato, T.; Taguchi, H.; Omi, J.; Sakamoto, K. [Ishikawajima-Harima Heavy Industries Co. Ltd., Tokyo (Japan)

    2000-01-01

    IHI has been developing the SETF (Supersonic Engine Test Facility) to aim at the research and development of engines for the next generation commercial supersonic transport in the NAL (National Aerospace Laboratory in Japan). The SETF will supply the functions to test the supersonic engine performance in high altitude flight condition and supersonic intake-engine matching. The semi-free jet test mode was adopted for the supersonic intake-engine matching test, but this test configuration has not been conducted previously in Japan and there were a large number of unknown factors. IHI has developed a sub-scale test model in cooperation with NAL to identify the test conditions and a start sequence of the semi-free jet test mode. In addition, the designs of facility component were optimized and verified by using the CFD (Computational Fluid Dynamics) method. (author)

  10. D-558-2 launch and flight

    Science.gov (United States)

    1954-01-01

    ,000 feet and push over into a slight dive, Crossfield made aviation history on November 20, 1953, when he flew to Mach 2.005 (1,291 miles per hour). He became the first pilot to reach Mach 2 in this, the only flight in which the Skyrocket flew that fast. Following this flight, Crossfield and NACA pilots Joseph A. Walker and John B. McKay flew the airplane for such purposes as to gather data on pressure distribution, structural loads, and structural heating. The last flight in the program occurred on December 20, 1956, when McKay obtained dynamic stability data and sound-pressure levels at transonic speeds and above. Meanwhile, NACA 145 had completed 21 contractor flights by Douglas Aircraft pilots Eugene F. May and Bill Bridgeman in November 1950. In this jet-and-rocket-propelled craft, Scott Crossfield and Walter Jones began the NACA investigation of pitchup, which lasted from September 1951 well into the summer of 1953. They flew the Skyrocket with a variety of wing-fence, wing-slat, and leading-edge chord extension configurations, performing various maneuvers as well as straight-and-level flying at transonic speeds. While fences significantly aided recovery from pitchup conditions, leading edge chord extensions did not, disproving wind-tunnel tests to the contrary. Slats (long, narrow auxiliary airfoils) in the fully open position eliminated pitchup except in the speed range around Mach 0.8 to 0.85. In June 1954, Crossfield began an investigation of the effects of external stores (bomb shapes and fuel tanks) upon the D-558-2 transonic behavior. McKay and Stanley Butchart completed the NACA investigation of this issue, with McKay flying the final mission on August 28, 1956. Besides setting several records, the Skyrocket pilots had gathered important data and understanding about what would and would not work to provide stable, controlled flight of a swept-wing aircraft in the transonic and supersonic flight regimes. The data they gathered also helped to enable a better

  11. Detonation in supersonic radial outflow

    KAUST Repository

    Kasimov, Aslan R.

    2014-11-07

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

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

    Science.gov (United States)

    2014-08-18

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

  13. Overview of the LaNCETS Flight Experiment and CFD Analysis. Supplemental Movies

    Science.gov (United States)

    Cliatt, Larry J., II; Haering, Edward A., Jr.; Bui, Trong

    2008-01-01

    This presentation focuses on nearfield airborne pressure signatures from the Lift and Nozzle Change Effect on Tail Shocks (LaNCETS) flight test experiment. The primary motivation for nearfield probing in the supersonic regime is to measure the shock structure of aircraft in an ongoing effort to overcome the overland sonic boom barrier for commercial supersonic transportation. LaNCETS provides the opportunity to investigate lift distribution and engine plume effects. During Phase 1 flight testing an F-15B was used to probe the F-15 LaNCETS aircraft in order to validate CFD and pre-flight prediction tools. A total of 29 probings were taken at 40,000 ft. altitude at Machs 1.2, 1.4 and 1.6. LaNCETS Phase 1 flight data are presented as a detailed pressure signature superimposed over a picture of the LaNCETS aircraft. The attenuation of the Inlet-Canard shocks with distance as well as its forward propagation and the coalescence of the noseboom shock are illustrated. A detailed CFD study on a simplified LaNCETS aircraft jet nozzle was performed providing the ability to more accurately capture the shocks from the propulsion system and emphasizing how under- and over-expanding the nozzle affects the existence of shock trains inside the jet plume. With Phase 1 being a success preparations are being made to move forward to Phase 2. Phase 2 will fly similar flight conditions, but this time changing the aircraft's lift distribution by biasing the canard positions, and changing the plume shape by under- and over-expanding the nozzle. Nearfield probing will again be completed in the same manner as in Phase 1. An additional presentation focuses on LaNCETS CFD solution methodology. Discussions highlight grid preprocessing, grid shearing and stretching, flow solving and contour plots. Efforts are underway to better capture the flow features via grid modification and flow solution methodology, which will help to achieve better agreement with flight data. An included CD-ROM provides

  14. Application of advanced computational codes in the design of an experiment for a supersonic throughflow fan rotor

    Science.gov (United States)

    Wood, Jerry R.; Schmidt, James F.; Steinke, Ronald J.; Chima, Rodrick V.; Kunik, William G.

    1987-01-01

    Increased emphasis on sustained supersonic or hypersonic cruise has revived interest in the supersonic throughflow fan as a possible component in advanced propulsion systems. Use of a fan that can operate with a supersonic inlet axial Mach number is attractive from the standpoint of reducing the inlet losses incurred in diffusing the flow from a supersonic flight Mach number to a subsonic one at the fan face. The design of the experiment using advanced computational codes to calculate the components required is described. The rotor was designed using existing turbomachinery design and analysis codes modified to handle fully supersonic axial flow through the rotor. A two-dimensional axisymmetric throughflow design code plus a blade element code were used to generate fan rotor velocity diagrams and blade shapes. A quasi-three-dimensional, thin shear layer Navier-Stokes code was used to assess the performance of the fan rotor blade shapes. The final design was stacked and checked for three-dimensional effects using a three-dimensional Euler code interactively coupled with a two-dimensional boundary layer code. The nozzle design in the expansion region was analyzed with a three-dimensional parabolized viscous code which corroborated the results from the Euler code. A translating supersonic diffuser was designed using these same codes.

  15. A Study on the Estimation of Aeroheating upon the Warhead Nose at Supersonic Speed

    Institute of Scientific and Technical Information of China (English)

    LI Fu-song; TANG Li-tie; XU Min; MA Xu-hui

    2006-01-01

    An expression for estimating the aeroheating on a warhead nose at different supersonic speeds is proposed by incorporating CFD (computational fluid dynamics) and the least-square method. Compared with the traditional estimation formula, the expression is more accurate, convenient and can be used in the optimized design of warheads. The error from the result obtained in the test of a ball cartridge flight is less than 3 %. It satisfies the engineering requirements.

  16. Pdf prediction of supersonic hydrogen flames

    Science.gov (United States)

    Eifler, P.; Kollmann, W.

    1993-01-01

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

  17. A compressible multiphase framework for simulating supersonic atomization

    Science.gov (United States)

    Regele, Jonathan D.; Garrick, Daniel P.; Hosseinzadeh-Nik, Zahra; Aslani, Mohamad; Owkes, Mark

    2016-11-01

    The study of atomization in supersonic combustors is critical in designing efficient and high performance scramjets. Numerical methods incorporating surface tension effects have largely focused on the incompressible regime as most atomization applications occur at low Mach numbers. Simulating surface tension effects in high speed compressible flow requires robust numerical methods that can handle discontinuities caused by both material interfaces and shocks. A shock capturing/diffused interface method is developed to simulate high-speed compressible gas-liquid flows with surface tension effects using the five-equation model. This includes developments that account for the interfacial pressure jump that occurs in the presence of surface tension. A simple and efficient method for computing local interface curvature is developed and an acoustic non-dimensional scaling for the surface tension force is proposed. The method successfully captures a variety of droplet breakup modes over a range of Weber numbers and demonstrates the impact of surface tension in countering droplet deformation in both subsonic and supersonic cross flows.

  18. Terminal area energy management regime investigations utilizing an 0.030-scale model (47-0) of the space shuttle vehicle orbiter configuration 140A/B/C/R in the Ames Research Center 11 x 11 foot transonic wind tunnel (0A148), volume 1

    Science.gov (United States)

    Hawthorne, P. J.

    1976-01-01

    Data obtained in wind tunnel tests are presented. The objectives of the tests were to: (1) obtain pressure distributions, forces and moments over the vehicle 5 Orbiter in the terminal area energy management (TAEM) and approach phases of flight; (2) obtain elevon and rudder hinge moments in the TAEM and approach phases of flight; (3) obtain body flap and elevon loads for verification of loads balancing with integrated pressure distributions; and (4) obtain pressure distributions near the short OMS pods in the high subsonic, transonic and low supersonic Mach number regimes. Testing was conducted over a Mach number range from 0.6 to 1.4 with Reynolds number variations from 4.57 million to 2.74 million per foot. Model angle-of-attack was varied from -4 to 16 degrees and angles of side slip ranged from -8 to 8 degrees.

  19. Terminal area energy management regime investigations utilizing an 0.030-scale model (47-0) of the space shuttle vehicle orbiter configuration 140A/B/C/R in the Ames Research Center 11 x 11 foot transonic wind tunnel (OH/48)

    Science.gov (United States)

    Hawthorne, P. J.

    1976-01-01

    Data obtained in a wind tunnel test were examined to: (1) obtain pressure distributions, forces and moments over the vehicle 5 Orbiter in the terminal area energy management (TAEM) and approach phases of flight; (2) obtain elevon and rudder hinge moments in the TAEM and approach phases of flight; (3) obtain body flap and elevon loads for verification of loads balancing with integrated pressure distributions; and (4) obtain pressure distributions near the short OMS pods in the high subsonic, transonic and low supersonic Mach number regimes. Testing was conducted over a Mach number range from 0.6 to 1.4 with Reynolds number variations from 7.57 x 1 million to 2.74 x 1 million per foot. Model angle of attack was varied from -4 to 16 degrees and angles of sideslip ranged from -8 to 8 degrees.

  20. Experiments on free and impinging supersonic microjets

    Energy Technology Data Exchange (ETDEWEB)

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

    2008-05-15

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

  1. Experiments on free and impinging supersonic microjets

    Science.gov (United States)

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

    2008-05-01

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

  2. Unsteady transonic aerodynamics and aeroelastic calculations at low-supersonic freestreams

    Science.gov (United States)

    Guruswamy, Guru P.; Goorjian, Peter M.

    1988-01-01

    A computational procedure is presented to simulate transonic unsteady flows and corresponding aeroelasticity of wings at low-supersonic freestreams. The flow is modeled by using the transonic small-perturbation theory. The structural equations of motions are modeled using modal equations of motion directly coupled with aerodynamics. Supersonic freestreams are simulated by properly accounting for the boundary conditions based on pressure waves along the flow characteristics in streamwise planes. The flow equations are solved using the time-accurate, alternating-direction implicit finite-difference scheme. The coupled aeroelastic equations of motion are solved by an integration procedure based on the time-accurate, linear-acceleration method. The flow modeling is verified by comparing calculations with experiments for both steady and unsteady flows at supersonic freestreams. The unsteady computations are made for oscillating wings. Comparisons of computed results with experiments show good agreement. Aeroelastic responses are computed for a rectangular wing at Mach numbers ranging from subtransonic to upper-transonic (supersonic) freestreams. The extension of the transonic dip into the upper transonic regime is illustrated.

  3. DAST in Flight

    Science.gov (United States)

    1980-01-01

    The modified BQM-34 Firebee II drone with Aeroelastic Research Wing (ARW-1), a supercritical airfoil, during a 1980 research flight. The remotely-piloted vehicle, which was air launched from NASA's NB-52B mothership, participated in the Drones for Aerodynamic and Structural Testing (DAST) program which ran from 1977 to 1983. The DAST 1 aircraft (Serial #72-1557), pictured, crashed on 12 June 1980 after its right wing ripped off during a test flight near Cuddeback Dry Lake, California. The crash occurred on the modified drone's third free flight. These are the image contact sheets for each image resolution of the NASA Dryden Drones for Aerodynamic and Structural Testing (DAST) Photo Gallery. From 1977 to 1983, the Dryden Flight Research Center, Edwards, California, (under two different names) conducted the DAST Program as a high-risk flight experiment using a ground-controlled, pilotless aircraft. Described by NASA engineers as a 'wind tunnel in the sky,' the DAST was a specially modified Teledyne-Ryan BQM-34E/F Firebee II supersonic target drone that was flown to validate theoretical predictions under actual flight conditions in a joint project with the Langley Research Center, Hampton, Virginia. The DAST Program merged advances in electronic remote control systems with advances in airplane design. Drones (remotely controlled, missile-like vehicles initially developed to serve as gunnery targets) had been deployed successfully during the Vietnamese conflict as reconnaissance aircraft. After the war, the energy crisis of the 1970s led NASA to seek new ways to cut fuel use and improve airplane efficiency. The DAST Program's drones provided an economical, fuel-conscious method for conducting in-flight experiments from a remote ground site. DAST explored the technology required to build wing structures with less than normal stiffness. This was done because stiffness requires structural weight but ensures freedom from flutter-an uncontrolled, divergent oscillation of

  4. Design project: LONGBOW supersonic interceptor

    Science.gov (United States)

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

    1993-01-01

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

  5. On highly focused supersonic microjets

    CERN Document Server

    Tagawa, Yoshiyuki; Willem, Claas; Peters, Ivo R; van der Meer, Deveraj; Sun, Chao; Prosperetti, Andrea; Lohse, Detlef

    2011-01-01

    By focusing a laser pulse in a liquid-filled glass-microcapillary open at one end, a small mass of liquid is instantaneously vapourised. This leads to a shock wave which travels towards the concave free surface where it generates a high-speed microjet. The initial shape of the meniscus plays a dominant role in the process. The velocity of the jet can reach supersonic speeds up to 850\\,m/s while maintaining a very sharp geometry. The entire evolution of the jet is observed by high-speed recordings of up to $10^6\\,$fps. A parametric study of the jet velocity as a function of the contact angle of the liquid-glass interface, the energy absorbed by the liquid, the diameter of the capillary tube, and the distance between the laser focus and the free surface is performed, and the results are rationalised. The method could be used for needle-free injection of vaccines or drugs.

  6. Supersonic Cloud Collision-II

    CERN Document Server

    Anathpindika, S

    2009-01-01

    In this, second paper of the sequel of two papers, we present five SPH simulations of fast head-on cloud collisions and study the evolution of the ram pressure confined gas slab. Anathpindika (2008) (hereafter paper I) considered highly supersonic cloud collisions and examined the effect of bending and shearing instabilities on the shocked gas slab. The post-collision shock here, as in paper I, is also modelled by a simple barotropic equation of state (EOS). However, a much stiffer EOS is used to model the shock resulting from a low velocity cloud collision. We explore the parameter space by varying the pre-collision velocity and the impact parameter. We observe that pressure confined gas slabs become Jeans unstable if the sound crossing time, $t_{cr}$, is much larger than the freefall time, $t_{ff}$, of putative clumps condensing out of them. Self gravitating clumps may spawn multiple/larger $N$-body star clusters. We also suggest that warmer gas slabs are unlikely to fragment and may end up as diffuse gas c...

  7. Characteristics of laser supersonic heating method for producing micro metallic particles

    Science.gov (United States)

    Lin, Shih-Lung; Lin, Jehnming

    2005-10-01

    In this article, the authors analyzed the process characteristics of laser supersonic heating method for producing metallic particles and predicted the in-flight tracks and shapes of micro-particles. A pulse Nd-YAG laser was used to heat the carbon steel target placed within an air nozzle. The high-pressure air with supersonic velocity was used to carry out carbon steel particles in the nozzle. The shock wave structures at the nozzle exit were visualized by the shadowgraph method. The carbon steel particles produced by laser supersonic heating method were grabbed and the spraying angles of the particle tracks were visualized. The velocity of the in-flight particles was measured by a photodiode sensor and compared with the numerical result. The solidification of carbon steel particles with diameters of 1-50 μm in compressible flow fields were investigated. The result shows that there is no significant difference in the dimension of solid carbon steel particles produced at shock wave fields under various entrance pressures (3-7 bar) with a constant laser energy radiation.

  8. LDSD POST2 Modeling Enhancements in Support of SFDT-2 Flight Operations

    Science.gov (United States)

    White, Joseph; Bowes, Angela L.; Dutta, Soumyo; Ivanov, Mark C.; Queen, Eric M.

    2016-01-01

    Program to Optimize Simulated Trajectories II (POST2) was utilized to develop trajectory simulations characterizing all flight phases from drop to splashdown for the Low-Density Supersonic Decelerator (LDSD) project's first and second Supersonic Flight Dynamics Tests (SFDT-1 and SFDT-2) which took place June 28, 2014 and June 8, 2015, respectively. This paper describes the modeling improvements incorporated into the LDSD POST2 simulations since SFDT-1 and presents how these modeling updates affected the predicted SFDT-2 performance and sensitivity to the mission design. The POST2 simulation flight dynamics support during the SFDT-2 launch, operations, and recovery is also provided.

  9. SFDT-1 Camera Pointing and Sun-Exposure Analysis and Flight Performance

    Science.gov (United States)

    White, Joseph; Dutta, Soumyo; Striepe, Scott

    2015-01-01

    The Supersonic Flight Dynamics Test (SFDT) vehicle was developed to advance and test technologies of NASA's Low Density Supersonic Decelerator (LDSD) Technology Demonstration Mission. The first flight test (SFDT-1) occurred on June 28, 2014. In order to optimize the usefulness of the camera data, analysis was performed to optimize parachute visibility in the camera field of view during deployment and inflation and to determine the probability of sun-exposure issues with the cameras given the vehicle heading and launch time. This paper documents the analysis, results and comparison with flight video of SFDT-1.

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

    Science.gov (United States)

    Chen, Gui-Qiang

    2017-08-01

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

  11. Bibliography of Supersonic Cruise Research (SCR) program from 1977 to mid-1980

    Science.gov (United States)

    Hoffman, S.

    1980-01-01

    The supersonic cruise research (SCR) program, initiated in July 1972, includes system studies and the following disciplines: propulsion, stratospheric emission impact, structures and materials, aerodynamic performance, and stability and control. In a coordinated effort to provide a sound basis for any future consideration that may be given by the United States to the development of an acceptable commercial supersonic transport, integration of the technical disciplines was undertaken, analytical tools were developed, and wind tunnel, flight, and laboratory investigations were conducted. The present bibliography covers the time period from 1977 to mid-1980. It is arranged according to system studies and the above five SCR disciplines. There are 306 NASA reports and 135 articles, meeting papers, and company reports cited.

  12. Sustainable urban regime adjustments

    DEFF Research Database (Denmark)

    Quitzau, Maj-Britt; Jensen, Jens Stissing; Elle, Morten

    2013-01-01

    The endogenous agency that urban governments increasingly portray by making conscious and planned efforts to adjust the regimes they operate within is currently not well captured in transition studies. There is a need to acknowledge the ambiguity of regime enactment at the urban scale. This directs...... attention to the transformative implications of conscious strategic maneuvering by incumbent regime actors, when confronting regime structurations. This article provides insight to processes of regime enactment performed by local governments by applying a flow-oriented perspective on regime dynamics...

  13. Supersonic combustion engine testbed, heat lightning

    Science.gov (United States)

    Hoying, D.; Kelble, C.; Langenbahn, A.; Stahl, M.; Tincher, M.; Walsh, M.; Wisler, S.

    1990-01-01

    The design of a supersonic combustion engine testbed (SCET) aircraft is presented. The hypersonic waverider will utilize both supersonic combustion ramjet (SCRAMjet) and turbofan-ramjet engines. The waverider concept, system integration, electrical power, weight analysis, cockpit, landing skids, and configuration modeling are addressed in the configuration considerations. The subsonic, supersonic and hypersonic aerodynamics are presented along with the aerodynamic stability and landing analysis of the aircraft. The propulsion design considerations include: engine selection, turbofan ramjet inlets, SCRAMjet inlets and the SCRAMjet diffuser. The cooling requirements and system are covered along with the topics of materials and the hydrogen fuel tanks and insulation system. A cost analysis is presented and the appendices include: information about the subsonic wind tunnel test, shock expansion calculations, and an aerodynamic heat flux program.

  14. Simulating Supersonic Turbulence in Galaxy Outflows

    CERN Document Server

    Scannapieco, Evan

    2010-01-01

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

  15. Flight Test of an Intelligent Flight-Control System

    Science.gov (United States)

    Davidson, Ron; Bosworth, John T.; Jacobson, Steven R.; Thomson, Michael Pl; Jorgensen, Charles C.

    2003-01-01

    inputs with the outputs provided to instrumentation only. The IFCS was not used to control the airplane. In another stage of the flight test, the Phase I pre-trained neural network was integrated into a Phase III version of the flight control system. The Phase I pretrained neural network provided realtime stability and control derivatives to a Phase III controller that was based on a stochastic optimal feedforward and feedback technique (SOFFT). This combined Phase I/III system was operated together with the research flight-control system (RFCS) of the F-15 ACTIVE during the flight test. The RFCS enables the pilot to switch quickly from the experimental- research flight mode back to the safe conventional mode. These initial IFCS ACP flight tests were completed in April 1999. The Phase I/III flight test milestone was to demonstrate, across a range of subsonic and supersonic flight conditions, that the pre-trained neural network could be used to supply real-time aerodynamic stability and control derivatives to the closed-loop optimal SOFFT flight controller. Additional objectives attained in the flight test included (1) flight qualification of a neural-network-based control system; (2) the use of a combined neural-network/closed-loop optimal flight-control system to obtain level-one handling qualities; and (3) demonstration, through variation of control gains, that different handling qualities can be achieved by setting new target parameters. In addition, data for the Phase-II (on-line-learning) neural network were collected, during the use of stacked-frequency- sweep excitation, for post-flight analysis. Initial analysis of these data showed the potential for future flight tests that will incorporate the real-time identification and on-line learning aspects of the IFCS.

  16. The IMF as a function of supersonic turbulence

    CERN Document Server

    Motta, Clio Bertelli; Glover, Simon C O; Klessen, Ralf S; Pasquali, Anna

    2016-01-01

    Recent studies seem to suggest that the stellar initial mass function (IMF) in early-type galaxies might be different from a classical Kroupa or Chabrier IMF, i.e. contain a larger fraction of the total mass in low-mass stars. From a theoretical point of view, supersonic turbulence has been the subject of interest in many analytical theories proposing a strong correlation with the characteristic mass of the core mass function (CMF) in star forming regions, and as a consequence with the stellar IMF. Performing two suites of smoothed particles hydrodynamics (SPH) simulations with different mass resolutions, we aim at testing the effects of variations in the turbulent properties of a dense, star forming molecular cloud on the shape of the system mass function in different density regimes. While analytical theories predict a shift of the peak of the CMF towards lower masses with increasing velocity dispersion of the cloud, we observe in the low-density regime the opposite trend, with high Mach numbers giving rise...

  17. Supersonic Flutter of Laminated Curved Panels

    Directory of Open Access Journals (Sweden)

    M. Ganapathi

    1995-04-01

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

  18. Supersonic gas shell for puff pinch experiments

    Science.gov (United States)

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

    1982-09-01

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

  19. The Effect of the Recombination Shock behind a Backward Step on the Mixing Characteristics of an Inclined Sonic Methane Jet in a Supersonic Crossflow

    Science.gov (United States)

    Wen, A. C. Y.; Chang, B. Y. C.; Su, C. Y. H.; Yuan, D. H. F.

    The scramjet engines have been extensively studied for use in aircraft and future space transportation systems operating at speeds of about Mach 5 and above. At these high flight velocities, the incoming air is slowed down and maintained supersonic speed within the combustor

  20. Plasma-enhanced mixing and flameholding in supersonic flow

    Science.gov (United States)

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

    2015-01-01

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

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

    Institute of Scientific and Technical Information of China (English)

    2002-01-01

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

  2. Ignition length study of jp-8 + 100 in a supersonic duct

    Science.gov (United States)

    Bateup, M. L.

    2016-07-01

    In scramjets, hydrocarbon fuels are being considered for their endothermic potential and for use in flights where compact, volume critical designs are required at flight speeds at Mach 5+. Long-chain hydrocarbon (LCHC) fuels, like aviation kerosene, have handling and storage advantages over hazardous and volatile fuels, like hydrogen, that are more aligned with current flight systems. This research investigates the conditions under which kerosene fuel (JP-8 + 100) may be used in a supersonic duct at a hypervelocity impulse facility. Experimental data on kerosene ignition lengths for temperatures in the range 1100-1550 K, pressure of 1 atm, and equivalence ratios of 0.2-2.5 are compared with ignition delay correlations from literature.

  3. Instability of Supersonic Cold Streams Feeding Galaxies I: Linear Kelvin-Helmholtz Instability with Body Modes

    CERN Document Server

    Mandelker, Nir; Dekel, Avishai; Birnboim, Yuval; Burkert, Andreas; Krumholz, Mark R; Steinberg, Elad

    2016-01-01

    Massive galaxies at high redshift are predicted to be fed from the cosmic web by narrow, dense, cold streams. These streams penetrate supersonically through the hot medium encompassed by a stable shock near the virial radius of the dark-matter halo. Our long-term goal is to explore the heating and dissipation rate of the streams and their fragmentation and possible breakup, in order to understand how galaxies are fed, and how this affects their star-formation rate and morphology. We present here the first step, where we analyze the linear Kelvin-Helmholtz instability (KHI) of a cold, dense slab or cylinder flowing through a hot, dilute medium in the transonic regime. The current analysis is limited to the adiabatic case with no gravity and assuming equal pressure in the stream and the medium. By analytically solving the linear dispersion relation, we find a transition from a dominance of the familiar rapidly growing surface modes in the subsonic regime to more slowly growing body modes in the supersonic regim...

  4. The IMF as a function of supersonic turbulence

    Science.gov (United States)

    Bertelli Motta, C.; Clark, P. C.; Glover, S. C. O.; Klessen, R. S.; Pasquali, A.

    2016-11-01

    Recent studies seem to suggest that the stellar initial mass function (IMF) in early-type galaxies might be different from a classical Kroupa or Chabrier IMF, i.e. contain a larger fraction of the total mass in low-mass stars. From a theoretical point of view, supersonic turbulence has been the subject of interest in many analytical theories proposing a strong correlation with the characteristic mass of the core mass function (CMF) in star-forming regions, and as a consequence with the stellar IMF. Performing two suites of smoothed particle hydrodynamics (SPH) simulations with different mass resolutions, we aim at testing the effects of variations in the turbulent properties of a dense, star-forming molecular cloud on the shape of the system mass function in different density regimes. While analytical theories predict a shift of the peak of the CMF towards lower masses with increasing velocity dispersion of the cloud, we observe in the low-density regime the opposite trend, with high Mach numbers giving rise to a top-heavy mass distribution. For the high-density regime we do not find any trend correlating the Mach number with the characteristic mass of the resulting IMF, implying that the dynamics of protostellar accretion discs and fragmentation on small scales is not strongly affected by turbulence driven at the scale of the cloud. Furthermore, we suggest that a significant fraction of dense cores are disrupted by turbulence before stars can be formed in their interior through gravitational collapse. Although this particular study has limitations in its numerical resolution, we suggest that our results, along with those from other studies, cast doubt on the turbulent fragmentation models on the IMF that simply map the CMF to the IMF.

  5. Conditions for supersonic bent Marshak waves

    CERN Document Server

    Xu, Qiang; Li, Jing; Dan, Jia-kun; Wang, Kun-lun; Zhou, Shao-tong

    2014-01-01

    Supersonic radiation diffusion approximation is a useful way to study the radiation transportation. Considering the bent Marshak wave theory in 2-dimensions, and an invariable source temperature, we get the supersonic radiation diffusion conditions which are about the Mach number $M>8(1+\\sqrt{\\ep})/3$, and the optical depth $\\tau>1$. A large Mach number requires a high temperature, while a large optical depth requires a low temperature. Only when the source temperature is in a proper region these conditions can be satisfied. Assuming the material opacity and the specific internal energy depend on the temperature and the density as a form of power law, for a given density, these conditions correspond to a region about source temperature and the length of the sample. This supersonic diffusion region involves both lower and upper limit of source temperature, while that in 1-dimension only gives a lower limit. Taking $\\rm SiO_2$ and the Au for example, we show the supersonic region numerically.

  6. Dielectric barrier discharge source for supersonic beams

    Energy Technology Data Exchange (ETDEWEB)

    Luria, K.; Lavie, N.; Even, U. [Sackler School of Chemistry, Tel Aviv University, Tel Aviv 69978 (Israel)

    2009-10-15

    We present a new excitation source for pulsed supersonic beams. The excitation is based on dielectric barrier discharge in the beam. It produces cold beams of metastable atoms, dissociated neutral atoms from molecular precursors, and both positive and negative ions with high efficiency and reliability.

  7. Numerical and experimental investigations on supersonic ejectors

    Energy Technology Data Exchange (ETDEWEB)

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

    2005-02-01

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

  8. Azimuthally Varying Noise Reduction Techniques Applied to Supersonic Jets

    Science.gov (United States)

    Heeb, Nicholas S.

    An experimental investigation into the effect of azimuthal variance of chevrons and fluidically enhanced chevrons applied to supersonic jets is presented. Flow field measurements of streamwise and cross-stream particle imaging velocimetry were employed to determine the causes of noise reduction, which was demonstrated through acoustic measurements. Results were obtained in the over- and under- expanded regimes, and at the design condition, though emphasis was placed on the overexpanded regime due to practical application. Surveys of chevron geometry, number, and arrangement were undertaken in an effort to reduce noise and/or incurred performance penalties. Penetration was found to be positively correlated with noise reduction in the overexpanded regime, and negatively correlated in underexpanded operation due to increased effective penetration and high frequency penalty, respectively. The effect of arrangement indicated the beveled configuration achieved optimal abatement in the ideally and underexpanded regimes due to superior BSAN reduction. The symmetric configuration achieved optimal overexpanded noise reduction due to LSS suppression from improved vortex persistence. Increases in chevron number generally improved reduction of all noise components for lower penetration configurations. Higher penetration configurations reached levels of saturation in the four chevron range, with the potential to introduce secondary shock structures and generate additional noise with higher number. Alternation of penetration generated limited benefit, with slight reduction of the high frequency penalty caused by increased shock spacing. The combination of alternating penetration with beveled and clustered configurations achieved comparable noise reduction to the standard counterparts. Analysis of the entire data set indicated initial improvements with projected area that saturated after a given level and either plateaued or degraded with additional increases. Optimal reductions

  9. Condensed-Phase Mass Fraction in a Supersonic Molecular Beam Containing Clusters

    Science.gov (United States)

    Knuth, Eldon L.; Toennies, J. Peter

    2008-12-01

    For a supersonic molecular beam containing clusters, a relatively general and simple conservation-of-energy procedure for deducing from time-of-flight measurements the fraction of the beam in the condensed phase is developed. The procedure is applied to measurements for 4He beams formed by expansions which approach the two-phase region either near the critical point or to the liquid side of the critical point. The deduced values of the mass fraction are correlated using a scaling parameter which was used previously for correlating mean values of cluster sizes formed via fragmentation in free-jet expansions of liquid 4He.

  10. Structure and Chemistry of Atomic Clusters from Supersonic Beams.

    Science.gov (United States)

    Yang, Shi-He.

    A tandem time-of-flight (TOF) apparatus was designed to study the structure and chemistry of cold transition metal cluster ions from supersonic beams. By means of a photodissociation laser fluence dependence technique, binding energies of Nb_{rm x }^{+} (x = 2 - 20), Co_{rm x}^{+ } (x = 4 - 20) and etc. were found to generally increase with cluster size. The desorption energies of Nb_{rm x}N _2^{+} (x = 2 - 17) and Nb_{rm x} CO^{+} (x = 2 - 10) also increase with cluster size with some oscillations similar to the size dependent reactivities of these clusters. Photodetachment studies revealed that electron affinities of copper clusters increase with cluster size with a sharp even/odd alternation. Unlike other noble metals, Ag_{rm x}^ {-} clusters display two competing processes: photodissociation and photodetachment. Relative reactivities of cluster ions of Nb, Co, Ag, and etc. have been measured using a fast flow cluster reactor, displaying a similar function of cluster size to that of the neutrals. In addition, preliminary photoelectron experiments have been performed on Cu_{ rm x}^{-} and Nb _{rm x}^{-}. A magnetic Time-of-flight ultraviolet photoelectron spectrometer (MTOFUPS) has been developed to study electronic structures of cold metal and semiconductor cluster anions prepared in supersonic beams. Application of this spectrometer to carbon clusters with a F_2 laser (7.9 eV) allowed their electron affinities and UPS patterns to be measured,demonstrating a remarkable structural evolution of these clusters: Chains (C_2^{ -}-C_9^{-} ) - Rings (C_{10}^ {-}-C_{29}^ {-}) - Cages (C_{38 }^{-}-C_{84 }^{-}). In particular, the UPS of C_{60}^{-} is in excellent agreement with the CNDO/S calculation, providing a striking spectral evidence for the highly symmetric icosahedral soccer ball structure--Buckminsterfullerene. For comparison, the UPS of Si_ {rm x}^{-} and Ge_{rm x}^{ -} are presented. Unlike carbon clusters which prefer structures of low dimensionality, these

  11. National aero-space plane: Flight mechanics

    Science.gov (United States)

    Mciver, Duncan E.; Morrell, Frederick R.

    1990-01-01

    The current status and plans of the U.S. National Aero-Space Plane (NASP) program are reviewed. The goal of the program is to develop technology for single stage, hypersonic vehicles which use airbreathing propulsion to fly directly to orbit. The program features an X-30 flight research vehicle to explore altitude-speed regimes not amenable to ground testing. The decision to build the X-30 is now scheduled for 1993, with the first flight in the late 1990's. The flight mechanics, controls, flight management, and flight test considerations for the X-30 are discussed.

  12. Underexpanded Supersonic Plume Surface Interactions: Applications for Spacecraft Landings on Planetary Bodies

    Science.gov (United States)

    Mehta, M.; Sengupta, A.; Renno, N. O.; Norman, J. W.; Gulick, D. S.

    2011-01-01

    Numerical and experimental investigations of both far-field and near-field supersonic steady jet interactions with a flat surface at various atmospheric pressures are presented in this paper. These studies were done in assessing the landing hazards of both the NASA Mars Science Laboratory and Phoenix Mars spacecrafts. Temporal and spatial ground pressure measurements in conjunction with numerical solutions at altitudes of approx.35 nozzle exit diameters and jet expansion ratios (e) between 0.02 and 100 are used. Data from steady nitrogen jets are compared to both pulsed jets and rocket exhaust plumes at Mach approx.5. Due to engine cycling, overpressures and the plate shock dynamics are different between pulsed and steady supersonic impinging jets. In contrast to highly over-expanded (e plumes, results show that there is a relative ground pressure load maximum for moderately underexpanded (e approx.2-5) jets which demonstrate a long collimated plume shock structure. For plumes with e much >5 (lunar atmospheric regime), the ground pressure is minimal due to the development of a highly expansive shock structure. We show this is dependent on the stability of the plate shock, the length of the supersonic core and plume decay due to shear layer instability which are all a function of the jet expansion ratio. Asymmetry and large gradients in the spatial ground pressure profile and large transient overpressures are predominantly linked to the dynamics of the plate shock. More importantly, this study shows that thruster plumes exhausting into martian environments possess the largest surface pressure loads and can occur at high spacecraft altitudes in contrast to the jet interactions at terrestrial and lunar atmospheres. Theoretical and analytical results also show that subscale supersonic cold gas jets adequately simulate the flow field and loads due to rocket plume impingement provided important scaling parameters are in agreement. These studies indicate the critical

  13. Supersonic Turbulent Boundary Layer: DNS and RANS

    Institute of Scientific and Technical Information of China (English)

    XU Jing-Lei; MA Hui-Yang

    2007-01-01

    We assess the performance of a few turbulence models for Reynolds averaged Navier-Stokes (RANS) simulation of supersonic boundary layers, compared to the direct numerical simulations (DNS) of supersonic flat-plate turbulent boundary layers, carried out by Gao et al. [Chin. Phys. Lett. 22 (2005) 1709] and Huang et al. [Sci.Chin. 48 (2005) 614], as well as some available experimental data. The assessment is made for two test cases, with incoming Mach numbers and Reynolds numbers M = 2.25, Re = 365, 000/in, and M = 4.5, Re - 1.7 × 107/m,respectively. It is found that in the first case the prediction of RANS models agrees well with the DNS and the experimental data, while for the second case the agreement of the DNS models with experiment is less satisfactory.The compressibility effect on the RANS models is discussed.

  14. Turbulent Shear Layers in Supersonic Flow

    CERN Document Server

    Smits, Alexander J

    2006-01-01

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

  15. Study of active cooling for supersonic transports

    Science.gov (United States)

    Brewer, G. D.; Morris, R. E.

    1975-01-01

    The potential benefits of using the fuel heat sink of hydrogen fueled supersonic transports for cooling large portions of the aircraft wing and fuselage are examined. The heat transfer would be accomplished by using an intermediate fluid such as an ethylene glycol-water solution. Some of the advantages of the system are: (1) reduced costs by using aluminum in place of titanium, (2) reduced cabin heat loads, and (3) more favorable environmental conditions for the aircraft systems. A liquid hydrogen fueled, Mach 2.7 supersonic transport aircraft design was used for the reference uncooled vehicle. The cooled aircraft designs were analyzed to determine their heat sink capability, the extent and location of feasible cooled surfaces, and the coolant passage size and spacing.

  16. Supersonic Motions of Galaxies in Clusters

    CERN Document Server

    Faltenbacher, A; Nagai, D; Gottlöber, S; Faltenbacher, Andreas; Kravtsov, Andrey V.; Nagai, Daisuke; Gottloeber, Stefan

    2004-01-01

    We study motions of galaxies in galaxy clusters formed in the concordance LCDM cosmology. We use high-resolution cosmological simulations that follow dynamics of dark matter and gas and include various physical processes critical for galaxy formation: gas cooling, heating and star formation. Analysing motions of galaxies and the properties of intracluster gas in the sample of eight simulated clusters at z=0, we study velocity dispersion profiles of the dark matter, gas, and galaxies. We measure the mean velocity of galaxy motions and gas sound speed as a function of radius and calculate the average Mach number of galaxy motions. The simulations show that galaxies, on average, move supersonically with the average Mach number of ~1.4, approximately independent of the cluster-centric radius. The supersonic motions of galaxies may potentially provide an important source of heating for the intracluster gas by driving weak shocks and via dynamical friction, although these heating processes appear to be inefficient ...

  17. Control of star formation by supersonic turbulence

    CERN Document Server

    MacLow, M M; Low, Mordecai-Mark Mac; Klessen, Ralf S.

    2004-01-01

    Understanding the formation of stars in galaxies is central to much of modern astrophysics. For several decades it has been thought that stellar birth is primarily controlled by the interplay between gravity and magnetostatic support, modulated by ambipolar diffusion. Recently, however, both observational and numerical work has begun to suggest that support by supersonic turbulence rather than magnetic fields controls star formation. In this review we outline a new theory of star formation relying on the control by turbulence. We demonstrate that although supersonic turbulence can provide global support, it nevertheless produces density enhancements that allow local collapse. Inefficient, isolated star formation is a hallmark of turbulent support, while efficient, clustered star formation occurs in its absence. The consequences of this theory are then explored for both local star formation and galactic scale star formation. (Abstract abbreviated)

  18. Transonic and Low-Supersonic Aeroelastic Analysis of a Two-Degree Airfoil with a Freeplay Non-Linearity

    Science.gov (United States)

    KIM, DONG-HYUN; LEE, IN

    2000-07-01

    A two-degree-of-freedom airfoil with a freeplay non-linearity in the pitch and plunge directions has been analyzed in the transonic and low-supersonic flow region, where aerodynamic non-linearities also exist. The primary purpose of this study is to show aeroelastic characteristics due to freeplay structural non-linearity in the transonic and low-supersonic regions. The unsteady aerodynamic forces on the airfoil were evaluated using two-dimensional unsteady Euler code, and the resulting aeroelastic equations are numerically integrated to obtain the aeroelastic time responses of the airfoil motions and to investigate the dynamic instability. The present model has been considered as a simple aeroelastic model, which is equivalent to the folding fin of an advanced generic missile. From the results of the present study, characteristics of important vibration responses and aeroelastic instabilities can be observed in the transonic and supersonic regions, especially considering the effect of structural non-linearity in the pitch and plunge directions. The regions of limit-cycle oscillation are shown at much lower velocities, especially in the supersonic flow region, than the divergent flutter velocities of the linear structure model. It is also shown that even small freeplay angles can lead to severe dynamic instabilities and dangerous fatigue conditions for the flight vehicle wings and control fins.

  19. Conceptual Design of a Supersonic Jet Engine

    OpenAIRE

    Kareliusson, Joakim; Nordqvist, Melker

    2014-01-01

    This thesis is a response to the request for proposal issued by a joint collaboration between the AIAA Foundation and ASME/IGTI as a student competition to design a new turbofan engine intended for a conceptual supersonic business jet expected to enter service in 2025. Due to the increasing competition in the aircraft industry and the more stringent environmental legislations the new engine is expected to provide a lower fuel burn than the current engine intended for the aircraft to increase ...

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

    Science.gov (United States)

    Farshchi, M.

    1990-01-01

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

  1. Research of low boom and low drag supersonic aircraft design

    OpenAIRE

    Feng Xiaoqiang; Li Zhanke; Song Bifeng

    2014-01-01

    Sonic boom reduction will be an issue of utmost importance in future supersonic transport, due to strong regulations on acoustic nuisance. The paper describes a new multi-objective optimization method for supersonic aircraft design. The method is developed by coupling Seebass–George–Darden (SGD) inverse design method and multi-objective genetic algorithm. Based on the method, different codes are developed. Using a computational architecture, a conceptual supersonic aircraft design environment...

  2. Supersonic and subsonic measurements of mesospheric ionization.

    Science.gov (United States)

    Hale, L. C.; Nickell, L. C.; Kennedy, B.; Powell, T. A.

    1972-01-01

    An Arcas rocket-parachute system was used at night to compare supersonic and subsonic ionization measurements below 75 km. A hemispherical nose-tip probe was used on ascent and a parachute-borne blunt probe on descent to measure polar conductivities, which were due entirely to positive and negative ions. The velocity of the supersonic probe was Mach 2.5 at 50 km and 1.75 at 70 km; the blunt probe was subsonic below 71 km. Between 65 and 75 km the ratio of negative to positive conductivities (and thus of mobilities) determined by the blunt probe was about 1.2, and it approached 1 below this altitude range. The ratio obtained by the nose-tip probe varied from 1.5 at 75 km to .6 at 65 km, thus indicating a rapid variation of the effects of the shock wave on the sampled ions. The absolute values of positive conductivity measured subsonically and supersonically were essentially identical from 60 to 75 km, indicating that the sampled ions were unchanged by the shock. However, below 60 km the shock apparently 'broke up' the positive ions, as indicated by higher measured conductivities.

  3. Supersonic Jet Excitation using Flapping Injection

    CERN Document Server

    Hafsteinsson, Haukur; Andersson, Niklas; Cuppoletti, Daniel; Gutmark, Ephraim; Prisell, Erik

    2013-01-01

    Supersonic jet noise reduction is important for high speed military aircraft. Lower acoustic levels would reduce structural fatigue leading to longer lifetime of the jet aircraft. It is not solely structural aspects which are of importance, health issues of the pilot and the airfield per- sonnel are also very important, as high acoustic levels may result in severe hearing damage. It remains a major challenge to reduce the overall noise levels of the aircraft, where the supersonic exhaust is the main noise source for near ground operation. Fluidic injection into the supersonic jet at the nozzle exhaust has been shown as a promising method for noise reduction. It has been shown to speed up the mix- ing process of the main jet, hence reducing the kinetic energy level of the jet and the power of the total acoustic radiation. Furthermore, the interaction mechanism between the fluidic injection and the shock structure in the jet exhaust plays a crucial role in the total noise radia- tion. In this study, LES is used...

  4. Supersonic Gas-Liquid Cleaning System

    Science.gov (United States)

    Kinney, Frank

    1996-01-01

    The Supersonic Gas-Liquid Cleaning System Research Project consisted mainly of a feasibility study, including theoretical and engineering analysis, of a proof-of-concept prototype of this particular cleaning system developed by NASA-KSC. The cleaning system utilizes gas-liquid supersonic nozzles to generate high impingement velocities at the surface of the device to be cleaned. The cleaning fluid being accelerated to these high velocities may consist of any solvent or liquid, including water. Compressed air or any inert gas is used to provide the conveying medium for the liquid, as well as substantially reduce the total amount of liquid needed to perform adequate surface cleaning and cleanliness verification. This type of aqueous cleaning system is considered to be an excellent way of conducting cleaning and cleanliness verification operations as replacements for the use of CFC 113 which must be discontinued by 1995. To utilize this particular cleaning system in various cleaning applications for both the Space Program and the commercial market, it is essential that the cleaning system, especially the supersonic nozzle, be characterized for such applications. This characterization consisted of performing theoretical and engineering analysis, identifying desirable modifications/extensions to the basic concept, evaluating effects of variations in operating parameters, and optimizing hardware design for specific applications.

  5. Unsteady transverse injection of kerosene into a supersonic flow

    Institute of Scientific and Technical Information of China (English)

    2000-01-01

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

  6. Unsteady transverse injection of kerosene into a supersonic flow

    Institute of Scientific and Technical Information of China (English)

    徐胜利; R.D.Archer; B.E.Milton; 岳朋涛

    2000-01-01

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

  7. On the Coupling Between a Supersonic Turbulent Boundary Layer and a Flexible Structure

    Science.gov (United States)

    Frendi, Abdelkader

    1996-01-01

    A mathematical model and a computer code have been developed to fully couple the vibration of an aircraft fuselage panel to the surrounding flow field, turbulent boundary layer and acoustic fluid. The turbulent boundary layer model is derived using a triple decomposition of the flow variables and applying a conditional averaging to the resulting equations. Linearized panel and acoustic equations are used. Results from this model are in good agreement with existing experimental and numerical data. It is shown that in the supersonic regime, full coupling of the flexible panel leads to lower response and radiation from the panel. This is believed to be due to an increase in acoustic damping on the panel in this regime. Increasing the Mach number increases the acoustic damping, which is in agreement with earlier work.

  8. Skin Friction and Pressure Measurements in Supersonic Inlets Project

    Data.gov (United States)

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

  9. Acoustic measurements of models of military style supersonic nozzle jets

    Directory of Open Access Journals (Sweden)

    Ching-Wen Kuo

    2014-02-01

    Full Text Available Modern military aircraft jet engines are designed with variable-geometry nozzles to provide optimal thrust in different operating conditions, depending on the flight envelope. However, acoustic measurements for such nozzles are scarce, due to the cost involved in making full-scale measurements and the lack of details about the exact geometries of these nozzles. Thus the present effort at Pennsylvania State University (PSU in partnership with GE Aviation and the NASA Glenn Research Center is aiming to study and characterize the acoustic field produced by supersonic jets issuing from converging-diverging military style nozzles, and to identify and test promising noise reduction techniques. An equally important objective is to develop methodology for using data obtained from small- and moderate-scale experiments to reliably predict the full-scale engine noise. The experimental results presented show reasonable agreement between small-scale and medium-scale jets, as well as between heated jets and heat-simulated ones.

  10. Field Ionization detection of supersonic helium atom beams

    Science.gov (United States)

    Doak, R. B.

    2003-10-01

    Field ionization detectors (FID) may offer near-unity detection efficiency and nanoscale spatial resolution. To date, FID detection of molecular beams has been limited to effusive beams of broad Maxwellian velocity distributions. We report FID measurements on monoenergetic helium beams, including intensity measurements and time-of-flight measurements. The FID tips were carefully prepared and characterized in a field ionization microscope prior to use. With the supersonic helium beam we find a much smaller effective detection area ( 50 sq. nm) than was reported in the effusive helium beam experiments ( 200,000 sq. nm). This suggests that the FID ionization yield depends strongly on energy loss by the impinging atom during its initial collision with the FID surface: Our thermal energy, monoenergetic helium beam atoms likely lose little or no energy upon scattering from the clean tungsten FID surface, allowing the scattered atoms to escape the FID polarization field and therby reducing the ionization yield. To improve signal levels, inelastic scattering might be enhanced by use of lower beam velocities (present in the tails of a Maxwellian) or by adsorbing an overlayer on the FID tip (present at cryogenic tip temperatures). These factors likely explain the higher detection yields measured in the effusive beam experiments.

  11. Acoustic measurements of models of military style supersonic nozzle jets

    Institute of Scientific and Technical Information of China (English)

    Ching-Wen Kuo; Jérémy Veltin; Dennis K. McLaughlin

    2014-01-01

    Modern military aircraft jet engines are designed with variable-geometry nozzles to provide optimal thrust in different operating conditions, depending on the flight envelope. How-ever, acoustic measurements for such nozzles are scarce, due to the cost involved in making full-scale measurements and the lack of details about the exact geometries of these nozzles. Thus the present effort at Pennsylvania State University (PSU) in partnership with GE Aviation and the NASA Glenn Research Center is aiming to study and characterize the acoustic field produced by supersonic jets issuing from converging-diverging military style nozzles, and to identify and test promising noise reduction techniques. An equally important objective is to develop methodology for using data obtained from small-and moderate-scale experiments to reliably predict the full-scale engine noise. The experimental results presented show reasonable agreement between small-scale and medium-scale jets, as well as between heated jets and heat-simulated ones.

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

    Directory of Open Access Journals (Sweden)

    S.B.H Shah

    2012-01-01

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

  13. CFD Simulations of the Supersonic Inflatable Aerodynamic Decelerator (SIAD) Ballistic Range Tests

    Science.gov (United States)

    Brock, Joseph; Stern, Eric; Wilder, Michael

    2017-01-01

    A series of ballistic range tests were performed on a scaled model of the Supersonic Flight Demonstration Test (SFDT) intended to test the Supersonic Inflatable Aerodynamic Decelerator (SIAD) geometry. The purpose of these experiments were to provide aerodynamic coefficients of the vehicle to aid in mission and vehicle design. The experimental data spans the moderate Mach number range, $3.8-2.0$, with a total angle of attack ($alpha_T$) range, $10o-20o$. These conditions are intended to span the Mach-$alpha$ space for the majority of the SFDT experiment. In an effort to validate the predictive capabilities of Computational Fluid Dynamics (CFD) for free-flight aerodynamic behavior, numerical simulations of the ballistic range experiment are performed using the unstructured finite volume Navier-Stokes solver, US3D. Comparisons to raw vehicle attitude, and post-processed aerodynamic coefficients are made between simulated results and experimental data. The resulting comparisons for both raw model attitude and derived aerodynamic coefficients show good agreement with experimental results. Additionally, near body pressure field values for each trajectory simulated are investigated. Extracted surface and wake pressure data gives further insights into dynamic flow coupling leading to a potential mechanism for dynamic instability.

  14. Measuring autocratic regime stability

    Directory of Open Access Journals (Sweden)

    Joseph Wright

    2016-01-01

    Full Text Available Researchers measure regime stability in autocratic contexts using a variety of data sources that capture distinct concepts. Often this research uses concepts developed for the study of democratic politics, such as leadership change or institutionalized authority, to construct measures of regime breakdown in non-democratic contexts. This article assesses whether the measure a researcher chooses influences the results they obtain by examining data on executive leadership, political authority, and autocratic regimes. We illustrate the conceptual differences between these variables by extending recent studies in the literature on the political consequences of non-tax revenue and unearned foreign income.

  15. Exchange rate regime choice

    Directory of Open Access Journals (Sweden)

    Beker Emilija

    2006-01-01

    Full Text Available The choice of an adequate exchange rate regime proves to be a highly sensitive field within which the economic authorities present and confirm themselves. The advantages and disadvantages of fixed and flexible exchange rate regimes, which have been quite relativized from the conventional point of view, together with simultaneous, but not synchronized effects of structural and external factors, remain permanently questioned throughout a complex process of exchange rate regime decision making. The paper reflects the attempt of critical identification of the key exchange rate performances with emphasis on continuous non-uniformity and (uncertainty of shelf life of a relevant choice.

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

    Science.gov (United States)

    Chiles, Harry R.

    1988-01-01

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

  17. Accretion to a Magnetized Neutron Star in the "Propeller" Regime

    CERN Document Server

    Toropina, O D; Lovelace, R V E

    2006-01-01

    We investigate spherical accretion to a rotating magnetized star in the "propeller" regime using axisymmetric resistive magnetohydrodynamic simulations. The regime is predicted to occur if the magnetospheric radius is larger than the corotation radius and smaller than the light cylinder radius. The simulations show that accreting matter is expelled from the equatorial region of the magnetosphere and that it moves away from the star in a supersonic, disk-shaped outflow. At larger radial distances the outflow slows down and becomes subsonic. The equatorial matter outflow is initially driven by the centrifugal force, but at larger distances the pressure gradient force becomes significant. We find the fraction of the Bondi accretion rate which accretes to the surface of the star.

  18. Interstellar Probe: The Next Step To Flight

    Science.gov (United States)

    McNutt, Ralph; Zurbuchen, Thomas H.

    2016-07-01

    In the years following the discovery of the solar wind, the term "heliosphere" was coined and defined as "the region of interplanetary space where the solar wind is flowing supersonically." In June 1971, with the development of the Pioneer probes to Jupiter and beyond well underway, a session of the American Astronautical Society meeting considered scientific exploration reaching beyond the solar system and into the interstellar medium. Despite many discussions, studies, and meetings since, the most recent held under the auspices of the Keck Institute for Space Studies (8-11 September 2014 and 13-15 January 2015), such missions have been relegated to the '"future" due to the large distances and solar system escape speeds contemplated for their execution. In the meantime, the Voyager Interstellar Mission (VIM), consisting of the twin Voyager spacecraft almost 40 years since their respective launches, are making inroads into this region beyond the termination shock of the solar wind, a new region of the solid bodies of the solar system has been opened by the New Horizons flyby of the Pluto system, and the Cassini Ion and Neutral CAmera (INCA) and Interstellar Boundary Explorer (IBEX) have remotely sensed neutral atoms that have provided significant clues to the global structure of the interaction of the solar wind and interstellar medium. It is now time for a dedicated mission to the regime beyond the solar system to explore our galactic environment. A first, near-term implementation can be carried out with the near-current flight system technology. What is also clear is that the high speeds required will limit the spacecraft to a relatively small mass of no more than ~500 kg, regardless of the propulsion details. The recent success of the New Horizons mission at the Pluto system illustrates that with modern technologies, such spacecraft sizes can still accommodate the means to produce paradigm-shifting science, providing for a compelling scientific mission. The

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

    Directory of Open Access Journals (Sweden)

    Chen Jian

    2015-01-01

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

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

    Science.gov (United States)

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

    2016-07-01

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

  1. High speed titanium coating by Supersonic Laser Deposition

    OpenAIRE

    LUPOI, ROCCO

    2011-01-01

    PUBLISHED The importance of metal coating technologies drives the continuous improvement of metal deposition techniques for application in a wide range of industrial sectors. This work presents the foundations of a new process technology f or the deposition of t itanium coatings on steel tube substrates using supersonic powder streams and impact site laser heating , known as Supersonic Laser Deposition (SLD). M et...

  2. Low-Boom and Low-Drag Optimization of the Twin Engine Version of Silent Supersonic Business Jet

    Science.gov (United States)

    Sato, Koma; Kumano, Takayasu; Yonezawa, Masahito; Yamashita, Hiroshi; Jeong, Shinkyu; Obayashi, Shigeru

    Multi-Objective Optimization has been applied to a design problem of the twin engine concept for Silent Supersonic Business Jet (SSBJ). This problem aims to find main wing, body, tail wing and engine nacelle configurations, which can minimize both sonic boom and drag in a supersonic cruising flight. The multi-objective genetic algorithm (MOGA) coupled with the Kriging model has been used to globally and effectively search for optimal design candidates in the multi-objective problem. The drag and the sonic boom have been evaluated by the computational fluid dynamics (CFD) simulation and the waveform parameter method. As a result, the present optimization has successfully obtained low-boom and low-drag design candidates, which are better than the baseline design by more than 40% regarding each performance. Moreover, the structure of design space has been visualized by the self-organizing map (SOM).

  3. An Aileron Flutter Experiment and Analysis Using Semi-Span Model for the Small Supersonic Experimental Aircraft

    Science.gov (United States)

    Saitoh, Kenichi; Tamayama, Masato; Kikuchi, Takao; Machida, Shigeru; Nakamichi, Jiro

    This paper reports a wind-tunnel experiment and analysis that have been conducted under the National Experimental Airplane for Supersonic Transports (NEXST-1) project of JAXA. In order to perform the flight experiment, the design of the vehicle was examined from the stand point of aeroelasticity. The aileron buzz as well as flutter was of much concern for its aileron system on the main wing. Therefore, both wind-tunnel test and analysis were carried out by using a semi-span model with fuselage. Although the buzz was not observed in the test, damping responses of the aileron rotation mode were obtained. Critical damping was observed in supersonic flow, that meant a buzz could occur in ``region C'' of Lambourne's classification. Linear unsteady aerodynamic analysis is applicable to this type of buzz and the characteristics of the buzz of the model is discussed.

  4. Advanced Noise Abatement Procedures for a Supersonic Business Jet

    Science.gov (United States)

    Berton, Jeffrey J.; Jones, Scott M.; Seidel, Jonathan A.; Huff, Dennis L.

    2017-01-01

    Supersonic civil aircraft present a unique noise certification challenge. High specific thrust required for supersonic cruise results in high engine exhaust velocity and high levels of jet noise during takeoff. Aerodynamics of thin, low-aspect-ratio wings equipped with relatively simple flap systems deepen the challenge. Advanced noise abatement procedures have been proposed for supersonic aircraft. These procedures promise to reduce airport noise, but they may require departures from normal reference procedures defined in noise regulations. The subject of this report is a takeoff performance and noise assessment of a notional supersonic business jet. Analytical models of an airframe and a supersonic engine derived from a contemporary subsonic turbofan core are developed. These models are used to predict takeoff trajectories and noise. Results indicate advanced noise abatement takeoff procedures are helpful in reducing noise along lateral sidelines.

  5. New results in gravity dependent two-phase flow regime mapping

    Science.gov (United States)

    Kurwitz, Cable; Best, Frederick

    2002-01-01

    Accurate prediction of thermal-hydraulic parameters, such as the spatial gas/liquid orientation or flow regime, is required for implementation of two-phase systems. Although many flow regime transition models exist, accurate determination of both annular and slug regime boundaries is not well defined especially at lower flow rates. Furthermore, models typically indicate the regime as a sharp transition where data may indicate a transition space. Texas A&M has flown in excess of 35 flights aboard the NASA KC-135 aircraft with a unique two-phase package. These flights have produced a significant database of gravity dependent two-phase data including visual observations for flow regime identification. Two-phase flow tests conducted during recent zero-g flights have added to the flow regime database and are shown in this paper with comparisons to selected transition models. .

  6. Measurements of leading edge vortices in a supersonic stream

    Science.gov (United States)

    Milanovic, Ivana Milija

    An experimental investigation of the leading edge vortices from a 75° sweptback, sharp edge delta wing has been carried out in a Mach 2.49 stream. Five-hole conical probe traverses were conducted vertically and horizontally through the primary vortices at the trailing edge and at one half chord downstream station for 7° and 12° angles of attack. The main objective was to determine the Mach number and pressure distributions in the primary vortex and to present comparisons of flow properties at different survey stations. In response to the continued interest in efficient supersonic flight vehicles, particularly in the missile arena, the motivation for this research has been to provide the quantitative details of supersonic leading edge vortices, the understanding of which up to now has been largely based on flow visualizations and presumed similarity to low speed flows. As a prerequisite to the measurement campaign, the employed five-hole conical probe was numerically calibrated using a three-dimensional Thin Layer Navier-Stokes solver in order to circumvent the traditional experimental approach vastly demanding on resources. The pressure readings at the probe orifices were computed for a range of Mach numbers and pitch angles, and subsequently verified in wind tunnel tests. The calibration phase also demonstrated the profound influence of the probe bluntness on the nearby static pressure ports, its relevance to the ultimate modeling strategy and the resulting calibration charts. Flow diagnostics of the leading edge vortices included both qualitative flow visualizations, as well as quantitative measurements. Shadowgraphs provided information regarding the trajectory and relative size of the generated vortices while assuring that no probe-induced vortex breakdown occurred. Surface oil patterns revealed the general spanwise locations of leeward vortices, and confirmed topological similarity to their low speed counterparts. The probe measurements revealed substantial

  7. Miracle Flights

    Science.gov (United States)

    ... her future. Donate Now Make your donation today Saving Lives One Flight At A ... “To improve access to health care by providing financial assistance to low income children for commercial air ...

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

    Science.gov (United States)

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

    1992-01-01

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

  9. Instability of Supersonic Cold Streams Feeding Galaxies I: Linear Kelvin-Helmholtz Instability with Body Modes

    Science.gov (United States)

    Mandelker, Nir; Padnos, Dan; Dekel, Avishai; Birnboim, Yuval; Burkert, Andreas; Krumholz, Mark R.; Steinberg, Elad

    2016-09-01

    Massive galaxies at high redshift are predicted to be fed from the cosmic web by narrow, dense streams of cold gas that penetrate through the hot medium encompassed by a stable shock near the virial radius of the dark-matter halo. Our long-term goal is to explore the heating and dissipation rate of the streams and their fragmentation and possible breakup, in order to understand how galaxies are fed, and how this affects their star-formation rate and morphology. We present here the first step, where we analyze the linear Kelvin-Helmholtz instability (KHI) of a cold, dense slab or cylinder in 3D flowing supersonically through a hot, dilute medium. The current analysis is limited to the adiabatic case with no gravity. By analytically solving the linear dispersion relation, we find a transition from a dominance of the familiar rapidly growing surface modes in the subsonic regime to more slowly growing body modes in the supersonic regime. The system is parametrized by three parameters: the density contrast between stream and medium, the Mach number of stream velocity with respect to the medium, and the stream width with respect to the halo virial radius. A realistic choice for these parameters places the streams near the mode transition, with the KHI exponential-growth time in the range 0.01-10 virial crossing times for a perturbation wavelength comparable to the stream width. We confirm our analytic predictions with idealized hydrodynamical simulations. Our linear estimates thus indicate that KHI may be effective in the evolution of streams before they reach the galaxy. More definite conclusions await the extension of the analysis to the nonlinear regime and the inclusion of cooling, thermal conduction, the halo potential well, self-gravity and magnetic fields.

  10. Instability of supersonic cold streams feeding galaxies - I. Linear Kelvin-Helmholtz instability with body modes

    Science.gov (United States)

    Mandelker, Nir; Padnos, Dan; Dekel, Avishai; Birnboim, Yuval; Burkert, Andreas; Krumholz, Mark R.; Steinberg, Elad

    2016-12-01

    Massive galaxies at high redshift are predicted to be fed from the cosmic web by narrow, dense streams of cold gas that penetrate through the hot medium encompassed by a stable shock near the virial radius of the dark-matter halo. Our long-term goal is to explore the heating and dissipation rate of the streams and their fragmentation and possible breakup, in order to understand how galaxies are fed, and how this affects their star formation rate and morphology. We present here the first step, where we analyse the linear Kelvin-Helmholtz instability (KHI) of a cold, dense slab or cylinder in 3D flowing supersonically through a hot, dilute medium. The current analysis is limited to the adiabatic case with no gravity. By analytically solving the linear dispersion relation, we find a transition from a dominance of the familiar rapidly growing surface modes in the subsonic regime to more slowly growing body modes in the supersonic regime. The system is parametrized by three parameters: the density contrast between stream and medium, the Mach number of stream velocity with respect to the medium and the stream width with respect to the halo virial radius. A realistic choice for these parameters places the streams near the mode transition, with the KHI exponential-growth time in the range 0.01-10 virial crossing times for a perturbation wavelength comparable to the stream width. We confirm our analytic predictions with idealized hydrodynamical simulations. Our linear estimates thus indicate that KHI may be effective in the evolution of streams before they reach the galaxy. More definite conclusions await the extension of the analysis to the non-linear regime and the inclusion of cooling, thermal conduction, the halo potential well, self-gravity and magnetic fields.

  11. Supersonic Jet Interactions in a Plenum Chamber

    Directory of Open Access Journals (Sweden)

    K. M. Venugopal

    2004-07-01

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

  12. Numerical simulation of supersonic gap flow.

    Science.gov (United States)

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

    2015-01-01

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

  13. Numerical simulation of supersonic gap flow.

    Directory of Open Access Journals (Sweden)

    Xu Jing

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

  14. Coupling dynamic of twin supersonic jets

    Science.gov (United States)

    Kuo, Ching-Wen; Cluts, Jordan; Samimy, Mo

    2015-11-01

    In a supersonic shock-containing jet, the interaction of large-scale structures in the jet's shear layer with the shock waves generates acoustic waves. The waves propagate upstream, excite the jet initial shear layer instability, establish a feedback loop at certain conditions, and generate screech noise. The screech normally contains different modes of various strengths. Similarly, twin-jet plumes contain screech tones. If the dynamics of the two jet plumes are synchronized, the screech amplitude could be significantly amplified. There is a proposed analytical model in the literature for screech synchronization in twin rectangular jets. This model shows that with no phase difference in acoustic waves arriving at neighboring nozzle lips, twin-jet plumes feature a strong coupling with a significant level of screech tones. In this work the maximum nozzle separation distance for sustained screech synchronization and strong coupling is analytically derived. This model is used with our round twin-jet experiments and the predicted coupling level agrees well with the experimental results. Near-field microphone measurements and schlieren visualization along with the analytical model are used to investigate the coupling mechanisms of twin supersonic jets. Supported by ONR.

  15. World Nonproliferation Regime

    Institute of Scientific and Technical Information of China (English)

    Ouyang Liping; Wu Xingzuo

    2007-01-01

    2006 witnessed an intense struggle between nuclear proliferation and nonproliferation. Iran's nuclear issue and North Korea's nuclear test have cast a deep shadow over the current international nonproliferation regime. The international contest for civil nuclear development became especially fierce as global energy prices went up. Such a situation , to some extent, accelerated the pace of nuclear proliferation. Furthermore, the existing international nonproliferation regime, based upon the Nuclear Nonproliferation Treaty (NPT), was affected by loopholes, and the U.S. failed in its ambition to unite other forces to mend fences. The international community needs to come up with a comprehensive and long-term strategy to meet the demand for an effective future nonproliferation regime in a healthy nuclear order.

  16. Regimes of justification

    NARCIS (Netherlands)

    Arts, Irma; Buijs, A.E.; Verschoor, G.M.

    2017-01-01

    Legitimacy of environmental management and policies is an important topic in environmental research. Based on the notion of ‘regimes of justification’, we aim to analyse the dynamics in argumentations used to legitimize and de-legitimize Dutch nature conservation practices. Contrary to prior

  17. An Introduction to the Supersonic Molecular Beam Injection

    Institute of Scientific and Technical Information of China (English)

    2001-01-01

    Recently a new fuelling method with supersonic molecular beam injection (MBI) has been developed and used in the tokamaks experiments successfully. It is economical to develop and maintain. The advantages of supersonic MBI compared with the conventional of gas-puffing method are as follows: deep deposition of fuel, better fuelling efficiency, reduced recycling and pure plasma. Particle and energy confinement can be improved and density limit extended. This review described the Laval nozzle molecular beam and a simple collective model for the injection of a supersonic MBI into the tokamak plasma.

  18. Methodology for the Design of Streamline-Traced External-Compression Supersonic Inlets

    Science.gov (United States)

    Slater, John W.

    2014-01-01

    A design methodology based on streamline-tracing is discussed for the design of external-compression, supersonic inlets for flight below Mach 2.0. The methodology establishes a supersonic compression surface and capture cross-section by tracing streamlines through an axisymmetric Busemann flowfield. The compression system of shock and Mach waves is altered through modifications to the leading edge and shoulder of the compression surface. An external terminal shock is established to create subsonic flow which is diffused in the subsonic diffuser. The design methodology was implemented into the SUPIN inlet design tool. SUPIN uses specified design factors to design the inlets and computes the inlet performance, which includes the flow rates, total pressure recovery, and wave drag. A design study was conducted using SUPIN and the Wind-US computational fluid dynamics code to design and analyze the properties of two streamline-traced, external-compression (STEX) supersonic inlets for Mach 1.6 freestream conditions. The STEX inlets were compared to axisymmetric pitot, two-dimensional, and axisymmetric spike inlets. The STEX inlets had slightly lower total pressure recovery and higher levels of total pressure distortion than the axisymmetric spike inlet. The cowl wave drag coefficients of the STEX inlets were 20% of those for the axisymmetric spike inlet. The STEX inlets had external sound pressures that were 37% of those of the axisymmetric spike inlet, which may result in lower adverse sonic boom characteristics. The flexibility of the shape of the capture cross-section may result in benefits for the integration of STEX inlets with aircraft.

  19. Impact of ablator thickness and laser drive duration on a platform for supersonic, shockwave-driven hydrodynamic instability experiments

    Science.gov (United States)

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

    2017-03-01

    We discuss changes to a target design that improved the quality and consistency of data obtained through a novel experimental platform that enables the study of hydrodynamic instabilities in a compressible regime. The experiment uses a laser to drive steady, supersonic shockwave over well-characterized initial perturbations. Early experiments were adversely affected by inadequate experimental timescales and, potentially, an unintended secondary shockwave. These issues were addressed by extending the 4x1013 W/cm2 laser pulse from 19 ns to 28 ns, and increasing the ablator thickness from 185 μm to 500 μm. We present data demonstrating the performance of the platform.

  20. H-infinity based integrated flight/propulsion control design for a STOVL aircraft in transition flight

    Science.gov (United States)

    Garg, Sanjay; Mattern, Duane L.; Bright, Michelle; Ouzts, Peter

    1990-01-01

    This paper presents results from an application of H(infinity) control design methodology to a centralized integrated flight/propulsion control (IFPC) system design for a supersonic STOVL fighter aircraft in transition flight. The overall design methodology consists of a centralized IFPC design with controller partitioning. Design and evaluation vehicle models are summarized, and insight is provided into formulating the H(infinity) control problem such that it reflects the IFPC design objective. The H(infinity) controller is shown to provide decoupled command tracking for the design model. The controller order could be significantly reduced by modal residualization of the fast controller modes without any deterioration in performance.

  1. Reactive Collisions and Final State Analysis in Hypersonic Flight Regime

    Science.gov (United States)

    2016-09-13

    mechanics; Addison - Wesley , 2003. 37 DISTRIBUTION A. Approved for public release: distribution unlimited. [57] Porter, R.; Raff, L.; Miller, W. J. Chem. Phys...Corporation, 1964. [96] Liboff, R. L. Introductory Quantum Mechanics (4th ed.); Addison - Wesley , Mas- sachusetts, 2003. [97] Peterson, J.; Le Padellec, A

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

    Directory of Open Access Journals (Sweden)

    Silong Zhang

    2014-02-01

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

  3. Effect of Ablation on Heat Transfer & Performance of an Axisymmetric Supersonic Nozzle

    Science.gov (United States)

    Raza, M. A.

    The theoretical prediction of heat transfer effects in compressible turbulent flows is fundamentally complex phenomenon. Computational fluid dynamics (CFD) analysis is employed using Baldwin-Lomax turbulent model to simulate the effect of various nozzle geometry defects on the heat transfer state in supersonic nozzles. The study is done in terms of various heat transfer correlations and analogies by characteristic flow regimes numbers. Theses are calculated from modified Reynolds analogy for laminar flow over flat plate, the Dittus-Boelter correlation for fully developed turbulent flow, Sieder-Tate correlation for turbulent pipe flow with property variation and Bartz correlation for variable cross sections flow. In addition to these, modified Stanton correlation for high speed flows for pipe flow analogy is also used. The contribution of ablation on the formation of new nozzle contours at various regions is simulated using energy equation for charring ablators. The effect of heat transfer correlations on nozzle performance with various geometrical defects is also discussed. In addition to it, the supersonic flow behavior is also simulated in the nozzles in terms of pressure, temperature, Mach number and density distribution with ablated surfaces.

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

    Science.gov (United States)

    Wang, Yunpeng; Ozawa, Hiroshi; Nakamura, Yoshiaki

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

  5. Phase Coherence Analysis of Insect Flight

    CERN Document Server

    Shchekinova, E Y

    2009-01-01

    During insect flight a high--frequency wing oscillatory motion is generated. Here we present analysis of kinematic data of tethered Drosophila melanogaster flight. For a reliable detection of specific regimes of frequency variation we propose phase coherence method. The approach is generic and can be applied to nonstationary biological signals that feature multi- scale frequency variations. Our analysis reveals existence of distinct oscillatory modes.

  6. Gas turbine engine with supersonic compressor

    Science.gov (United States)

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

    2015-10-20

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

  7. Linear stability analysis of supersonic axisymmetric jets

    Directory of Open Access Journals (Sweden)

    Zhenhua Wan

    2014-01-01

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

  8. The shock waves in decaying supersonic turbulence

    CERN Document Server

    Smith, M D; Zuev, J M; Smith, Michael D.; Low, Mordecai-Mark Mac; Zuev, Julia M.

    2000-01-01

    We here analyse numerical simulations of supersonic, hypersonic andmagnetohydrodynamic turbulence that is free to decay. Our goals are tounderstand the dynamics of the decay and the characteristic properties of theshock waves produced. This will be useful for interpretation of observations ofboth motions in molecular clouds and sources of non-thermal radiation. We find that decaying hypersonic turbulence possesses an exponential tail offast shocks and an exponential decay in time, i.e. the number of shocks isproportional to t exp (-ktv) for shock velocity jump v and mean initialwavenumber k. In contrast to the velocity gradients, the velocity ProbabilityDistribution Function remains Gaussian with a more complex decay law. The energy is dissipated not by fast shocks but by a large number of low Machnumber shocks. The power loss peaks near a low-speed turn-over in anexponential distribution. An analytical extension of the mapping closuretechnique is able to predict the basic decay features. Our analytic descrip...

  9. Aeroacoustic properties of supersonic elliptic jets

    Science.gov (United States)

    Kinzie, Kevin W.; McLaughlin, Dennis K.

    1999-09-01

    The aerodynamic and acoustic properties of supersonic elliptic and circular jets are experimentally investigated. The jets are perfectly expanded with an exit Mach number of approximately 1.5 and are operated in the Reynolds number range of 25 000 to 50 000. The reduced Reynolds number facilitates the use of conventional hot-wire anemometry and a glow discharge excitation technique which preferentially excites the varicose or flapping modes in the jets. In order to simulate the high-velocity and low-density effects of heated jets, helium is mixed with the air jets. This allows the large-scale structures in the jet shear layer to achieve a high enough convective velocity to radiate noise through the Mach wave emission process.

  10. ARBITRARY INTERACTION OF PLANE SUPERSONIC FLOWS

    Directory of Open Access Journals (Sweden)

    P. V. Bulat

    2015-11-01

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

  11. Aeroelastic passive control optimization of supersonic composite wing with external stores

    Science.gov (United States)

    Sulaeman, E.; Abdullah, N. A.; Kashif, S. M.

    2017-03-01

    This paper provides a study on passive aeroelastic control optimization, by means of aeroelastic tailoring, of a composite supersonic wing equipped with external stores. The objective of the optimization is to minimize wing weight by considering the aeroelastic flutter and divergence instability speeds as constraints at several flight altitudes. The optimization variables are the composite ply angle and skin thickness of the wing box, wing rib and its control surfaces. The aeroelastic instability speed is set as constraint such that it should be higher than the flutter speed of a metallic base line model of supersonic wing having previously published. A finite element analysis is applied to determine the stiffness and mass matric of the wing and its multi stores. The boundary element method in the form of doublet lattice method is used to model the unsteady aerodynamic load. The results indicate that, for the present wing configuration, the high modulus Graphite/Epoxy composite provides a desired higher flutter speed and lower wing weight compare to that of Kevlar/Epoxy composite as well as the base line metallic wing materials. The aeroelastic boundary thus can be enlarged to higher speed zone and in the same time reduce the structural weight which is important for a further optimization process.

  12. Pilot Human Factors in Stall/Spin Accidents of Supersonic Fighter Aircraft

    Science.gov (United States)

    Anderson, S. B.; Enevoldson, E. K.; Nguyen, L. T.

    1983-01-01

    A study has been made of pilot human factors related to stall/spin accidents of supersonic fighter aircraft. The military specifications for flight at high angles of attack are examined. Several pilot human factors problems related to stall/spin are discussed. These problems include (1) unsatisfactory nonvisual warning cues; (2) the inability of the pilot to quickly determine if the aircraft is spinning out of control, or to recognize the type of spin; (3) the inability of the pilot to decide on and implement the correct spin recovery technique; (4) the inability of the pilot to move, caused by high angular rotation; and (5) the tendency of pilots to wait too long in deciding to abandon the irrecoverable aircraft. Psycho-physiological phenomena influencing pilot's behavior in stall/spin situations include (1) channelization of sensory inputs, (2) limitations in precisely controlling several muscular inputs, (3) inaccurate judgment of elapsed time, and (4) disorientation of vestibulo-ocular inputs. Results are given of pilot responses to all these problems in the F14A, F16/AB, and F/A-18A aircraft. The use of departure spin resistance and automatic spin prevention systems incorporated on recent supersonic fighters are discussed. These systems should help to improve the stall/spin accident record with some compromise in maneuverability.

  13. 1 Ft. x 1 Ft. Supersonic Wind Tunnel, Bldg. 37

    Data.gov (United States)

    Federal Laboratory Consortium — The 1- by 1-Foot Supersonic Wind Tunnel (1x), located in the Engine Research Building, is one of the most active test facilities at the Glenn Research Center. Used...

  14. Supersonic Jet Noise: Main Sources and Reduction Methodologies

    Directory of Open Access Journals (Sweden)

    Mohammadreza Azimi

    2014-07-01

    Full Text Available The large velocity ratio and the presence of Shocks in the exhaust plume from low bypass engines or supersonic jetliners cause jet noise to be dominant component of overall aircraft noise, and therefore is an important issue in design of the next generation of civil supersonic transport. Jet noise reduction technology also has application in the design of highperformance tactical aircraft. Jet noise is of particular concern on aircraft carriers where it is necessary for deck crew to be in relatively close proximity to the aircraft at takeoff and landing. In this paper, a brief discussion about supersonic jet noise sources and a review of the main passive technologies employed for the reduction of supersonic jet noise are presented.

  15. THERMAL AND AERODYNAMIC PERFORMANCES OF THE SUPERSONIC MOTION

    Directory of Open Access Journals (Sweden)

    Dejan P Ninković

    2010-01-01

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

  16. Nanomanufacturing of titania interfaces with controlled structural and functional properties by supersonic cluster beam deposition

    Science.gov (United States)

    Podestà, Alessandro; Borghi, Francesca; Indrieri, Marco; Bovio, Simone; Piazzoni, Claudio; Milani, Paolo

    2015-12-01

    Great emphasis is placed on the development of integrated approaches for the synthesis and the characterization of ad hoc nanostructured platforms, to be used as templates with controlled morphology and chemical properties for the investigation of specific phenomena of great relevance in interdisciplinary fields such as biotechnology, medicine, and advanced materials. Here, we discuss the crucial role and the advantages of thin film deposition strategies based on cluster-assembling from supersonic cluster beams. We select cluster-assembled nanostructured titania (ns-TiO2) as a case study to demonstrate that accurate control over morphological parameters can be routinely achieved, and consequently, over several relevant interfacial properties and phenomena, like surface charging in a liquid electrolyte, and proteins and nanoparticles adsorption. In particular, we show that the very good control of nanoscale morphology is obtained by taking advantage of simple scaling laws governing the ballistic deposition regime of low-energy, mass-dispersed clusters with reduced surface mobility.

  17. Nanomanufacturing of titania interfaces with controlled structural and functional properties by supersonic cluster beam deposition

    Energy Technology Data Exchange (ETDEWEB)

    Podestà, Alessandro, E-mail: alessandro.podesta@mi.infn.it, E-mail: pmilani@mi.infn.it; Borghi, Francesca; Indrieri, Marco; Bovio, Simone; Piazzoni, Claudio; Milani, Paolo, E-mail: alessandro.podesta@mi.infn.it, E-mail: pmilani@mi.infn.it [Centro Interdisciplinare Materiali e Interfacce Nanostrutturati (C.I.Ma.I.Na.), Dipartimento di Fisica, Università degli Studi di Milano, via Celoria 16, 20133 Milano (Italy)

    2015-12-21

    Great emphasis is placed on the development of integrated approaches for the synthesis and the characterization of ad hoc nanostructured platforms, to be used as templates with controlled morphology and chemical properties for the investigation of specific phenomena of great relevance in interdisciplinary fields such as biotechnology, medicine, and advanced materials. Here, we discuss the crucial role and the advantages of thin film deposition strategies based on cluster-assembling from supersonic cluster beams. We select cluster-assembled nanostructured titania (ns-TiO{sub 2}) as a case study to demonstrate that accurate control over morphological parameters can be routinely achieved, and consequently, over several relevant interfacial properties and phenomena, like surface charging in a liquid electrolyte, and proteins and nanoparticles adsorption. In particular, we show that the very good control of nanoscale morphology is obtained by taking advantage of simple scaling laws governing the ballistic deposition regime of low-energy, mass-dispersed clusters with reduced surface mobility.

  18. Regimes Of Helium Burning

    CERN Document Server

    Timmes, F X

    2000-01-01

    The burning regimes encountered by laminar deflagrations and ZND detonations propagating through helium-rich compositions in the presence of buoyancy-driven turbulence are analyzed. Particular attention is given to models of X-ray bursts which start with a thermonuclear runaway on the surface of a neutron star, and the thin shell helium instability of intermediate-mass stars. In the X-ray burst case, turbulent deflagrations propagating in the lateral or radial directions encounter a transition from the distributed regime to the flamlet regime at a density of 10^8 g cm^{-3}. In the radial direction, the purely laminar deflagration width is larger than the pressure scale height for densities smaller than 10^6 g cm^{-3}. Self-sustained laminar deflagrations travelling in the radial direction cannot exist below this density. Similarily, the planar ZND detonation width becomes larger than the pressure scale height at 10^7 g cm^{-3}, suggesting that a steady-state, self-sustained detonations cannot come into exista...

  19. Experimental Study on Electrostatic Guiding of Supersonic D2O Molecular Beam with Two Charged Wires

    Institute of Scientific and Technical Information of China (English)

    YIN Ya-Ling; XIA Yong; Chen Hai-Bo; YIN Jian-Ping

    2007-01-01

    We demonstrate the guiding of a supersonic heavy-water(D2O)molecular beam using a hollow electrostatic field generated by the combination of two parallel charged-wires and two grounded metal-plates,and report some new and preliminary experimental results.In the experiment,we detect the guiding signals by using the method of time-of-flight mass spectrum and study the dependence of the relative transmission of the beam guide on the guiding voltage.Our study shows that the relative transmission of the beam guide is increased linearly with increasing guiding voltage Vguid,and the number of the guided D2O molecules is at least increased by 89.4%when the guiding voltage is +20.0kV.Finally,some potential applications of our guiding scheme in the molecule optics are briefly discussed.

  20. Model predictions of latitude-dependent ozone depletion due to supersonic transport operations

    Science.gov (United States)

    Borucki, W. J.; Whitten, R. C.; Watson, V. R.; Woodward, H. T.; Riegel, C. A.; Capone, L. A.; Becker, T.

    1976-01-01

    Results are presented from a two-dimensional model of the stratosphere that simulates the seasonal movement of ozone by both wind and eddy transport, and contains all the chemistry known to be important. The calculated reductions in ozone due to NO2 injection from a fleet of supersonic transports are compared with the zonally averaged results of a three-dimensional model for a similar episode of injection. The agreement is good in the northern hemisphere, but is not as good in the southern hemisphere. Both sets of calculations show a strong corridor effect in that the predicted ozone depletions are largest to the north of the flight corridor for aircraft operating in the northern hemisphere.

  1. Fabrication and evaluation of advanced titanium structural panels for supersonic cruise aircraft

    Science.gov (United States)

    Payne, L.

    1977-01-01

    Flightworthy primary structural panels were designed, fabricated, and tested to investigate two advanced fabrication methods for titanium alloys. Skin-stringer panels fabricated using the weldbraze process, and honeycomb-core sandwich panels fabricated using a diffusion bonding process, were designed to replace an existing integrally stiffened shear panel on the upper wing surface of the NASA YF-12 research aircraft. The investigation included ground testing and Mach 3 flight testing of full-scale panels, and laboratory testing of representative structural element specimens. Test results obtained on full-scale panels and structural element specimens indicate that both of the fabrication methods investigated are suitable for primary structural applications on future civil and military supersonic cruise aircraft.

  2. Atlas occipitalization in a supersonic fighter pilot involved in a midair collision: a case report.

    Science.gov (United States)

    Gips, Hadas; Hiss, Jehuda; Davidson, Benjamin

    2010-11-01

    We report a case of a midair collision between two F16 fighter aircraft, in which one pilot survived and the other was ejected upon impact and his remains recovered from sea. In autopsy, no patholgy was detected, other than the expected evidence of mechanical trauma. No defects in the aircraft or faults in the parachute or ejection mechanism were found. Reconstruction of the shattered skull base and the cervical vertebrae revealed fusion of the atlanto-occipital joint (occipitalization) and a left paracondylar process. The effective diameter of the spinal canal was decreased by the abnormal articulation. Such malformations can cause a wide range of neurologic deficits. Considering the skill and alertness needed to operate a supersonic fighter aircraft, with the pressure applied by the heavy protective head gear and various G forces endured by the spinal column during flight, we postulate that the collision was related to the pilot's sudden incapacitation.

  3. Passive Thermal Control for the Low Density Supersonic Decelerator (LDSD) Test Vehicle Spin Motors Sub-System

    Science.gov (United States)

    Redmond, Matthew; Mastropietro, A. J.; Pauken, Michael; Mobley, Brandon

    2014-01-01

    Future missions to Mars will require improved entry, descent, and landing (EDL) technology over the Viking-heritage systems which recently landed the largest payload to date, the 900 kg Mars Science Laboratory. As a result, NASA's Low Density Supersonic Decelerator (LDSD) project is working to advance the state of the art in Mars EDL systems by developing and testing three key technologies which will enable heavier payloads and higher altitude landing sites on the red planet. These technologies consist of a large 33.5 m diameter Supersonic Disk Sail (SSDS) parachute and two different Supersonic Inflatable Aerodynamic Decelerator (SIAD) devices - a robotic class that inflates to a 6 m diameter torus (SIAD-R), and an exploration class that inflates to an 8 m diameter isotensoid (SIADE). All three technologies will be demonstrated on test vehicles at high earth altitudes in order to simulate the Mars EDL environment. Each vehicle will be carried to altitude by a large helium balloon, released, spun up using spin motors to stabilize the vehicle's trajectory, and accelerated to supersonic speeds using a large solid rocket motor. The vehicle will then be spun down using another set of spin motors, and will deploy either the SIAD-R or SIAD-E, followed by the SSDS parachute until the vehicle lands in the ocean. Component level testing and bounding analysis are used to ensure the survival of system components in extreme thermal environments and predict temperatures throughout the flight. This paper presents a general description of the thermal testing, model correlation, and analysis of the spin motor passive thermal control sub-system to maintain spin motor performance, prescribed vehicle trajectory, and structural integrity of the test vehicle. The spin motor subsystem is predicted to meet its requirements with margin.

  4. Passive Thermal Control for the Low Density Supersonic Decelerator (LDSD) Test Vehicle Spin Motors Sub-System

    Science.gov (United States)

    Redmond, Matthew; Mastropietro, A. J.; Pauken, Michael; Mobley, Brandon

    2014-01-01

    Future missions to Mars will require improved entry, descent, and landing (EDL) technology over the Viking-heritage systems which recently landed the largest payload to date, the 900 kg Mars Science Laboratory. As a result, NASA's Low Density Supersonic Decelerator (LDSD) project is working to advance the state of the art in Mars EDL systems by developing and testing three key technologies which will enable heavier payloads and higher altitude landing sites on the red planet. These technologies consist of a large 33.5 m diameter Supersonic Disk Sail (SSDS) parachute and two different Supersonic Inflatable Aerodynamic Decelerator (SIAD) devices - a robotic class that inflates to a 6 m diameter torus (SIAD-R), and an exploration class that inflates to an 8 m diameter isotensoid (SIADE). All three technologies will be demonstrated on test vehicles at high earth altitudes in order to simulate the Mars EDL environment. Each vehicle will be carried to altitude by a large helium balloon, released, spun up using spin motors to stabilize the vehicle's trajectory, and accelerated to supersonic speeds using a large solid rocket motor. The vehicle will then be spun down using another set of spin motors, and will deploy either the SIAD-R or SIAD-E, followed by the SSDS parachute until the vehicle lands in the ocean. Component level testing and bounding analysis are used to ensure the survival of system components in extreme thermal environments and predict temperatures throughout the flight. This paper presents a general description of the thermal testing, model correlation, and analysis of the spin motor passive thermal control sub-system to maintain spin motor performance, prescribed vehicle trajectory, and structural integrity of the test vehicle. The spin motor subsystem is predicted to meet its requirements with margin.

  5. FLIGHT INFORMATION

    Institute of Scientific and Technical Information of China (English)

    2011-01-01

    Check in With Singapore Airlines, Check out With Paypal Singapore Airlines customers in the United States, Singapore and five other Asia Pacific countries and territories can now pay for their flights with PayPal on singaporeair.com. This facility will progressively be made available to the airline’s customers in up to 17 countries, making this the largest collaboration between PayPal and an Asian carrier to date.

  6. Budgerigar flight in a varying environment: flight at distinct speeds?

    Science.gov (United States)

    Schiffner, Ingo; Srinivasan, Mandyam V

    2016-06-01

    How do flying birds respond to changing environments? The behaviour of budgerigars, Melopsittacus undulatus, was filmed as they flew through a tapered tunnel. Unlike flying insects-which vary their speed progressively and continuously by holding constant the optic flow induced by the walls-the birds showed a tendency to fly at only two distinct, fixed speeds. They switched between a high speed in the wider section of the tunnel, and a low speed in the narrower section. The transition between the two speeds was abrupt, and anticipatory. The high speed was close to the energy-efficient, outdoor cruising speed for these birds, while the low speed was approximately half this value. This is the first observation of the existence of two distinct, preferred flight speeds in birds. A dual-speed flight strategy may be beneficial for birds that fly in varying environments, with the high speed set at an energy-efficient value for flight through open spaces, and the low speed suited to safe manoeuvring in a cluttered environment. The constancy of flight speed within each regime enables the distances of obstacles and landmarks to be directly calibrated in terms of optic flow, thus facilitating simple and efficient guidance of flight through changing environments.

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

    Science.gov (United States)

    Clark, Kylen D.

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

  8. Analysis of the turbojet engine for propulsion of supersonic fighter airplanes / David S. Gabriel, Richard P. Krebs, E.Clinton Wilcox, Stanley L.Koutz

    Science.gov (United States)

    Gabriel, David S; Krebs, Richard P; Wilcox, E Clinton; Koutz, Stanley L

    1953-01-01

    An analytical investigation was made of two supersonic interceptor type airplanes to determine the most desirable turbojet engine characteristics for this application The airplanes were designed differently primarily because of the amount of subsonic flight incorporated in the flight plan--one flight having none and the other, a cruise radius of 400 nautical miles. Several power plant design variables were varied independently to determine the effect of changes in each parameter on airplane performance. These parameters included compressor pressure ratio, compressor efficiency, turbine-inlet temperature, afterburner temperature, engine specific weight, and air-handling capacity. The effects of using a convergent-divergent exhaust nozzle and of changing the design flight Mach number were also investigated.

  9. East Asian welfare regime

    DEFF Research Database (Denmark)

    Abrahamson, Peter

    2017-01-01

    . Political science studies tend to conclude that the region has left the old legacies behind and are now welfare states comparable to European states including them either in the conservative type (e.g. Japan), the liberal type (e.g. Korea) or even as a tendency in the Nordic type (e.g. China), while studies......The paper asks if East Asian welfare regimes are still productivist and Confucian? And, have they developed public care policies? The literature is split on the first question but (mostly) confirmative on the second. Care has to a large, but insufficient extent, been rolled out in the region...

  10. Phoenix Mars Scout Parachute Flight Behavior and Observations

    Science.gov (United States)

    Adams, Douglas S.; Witkowski, Allen; Kandis, Mike

    2011-01-01

    The data returned from the successful Phoenix Mars Scout mission are analyzed in order to determine characteristics and behaviors of the supersonic parachute that was used to slow the entry body during its descent to the surface. At least one significant drag reduction event was observed when the vehicle was traveling at Mach 1.6; this is consistent with previously reported terrestrial high altitude testing and is likely associated with an area oscillation of the parachute. The parachute is shown to possess some lateral instability relative to the anti-velocity vector that is also at a level that is consistent with the same historic data. Ramifications of the lateral instability and, in particular, the unsteadiness in the parachute drag are discussed as energizing elements of the entry body wrist mode. The apparent coefficient of drag for the parachute is calculated and shown to have relatively small variations on an average basis over the supersonic portion of flight.

  11. Stationary flow conditions in pulsed supersonic beams.

    Science.gov (United States)

    Christen, Wolfgang

    2013-10-21

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

  12. Supersonic Jet Noise Reduction Using Microjets

    Science.gov (United States)

    Gutmark, Ephraim; Cuppoletti, Dan; Malla, Bhupatindra

    2013-11-01

    Fluidic injection for jet noise reduction involves injecting secondary jets into a primary jet to alter the noise characteristics of the primary jet. A major challenge has been determining what mechanisms are responsible for noise reduction due to varying injector designs, injection parameters, and primary jets. The current study provides conclusive results on the effect of injector angle and momentum ux ratio on the acoustics and shock structure of a supersonic Md = 1.56 jet. It is shown that the turbulent mixing noise scales primarily with the injector momentum flux ratio. Increasing the injector momentum flux ratio increases streamwise vorticity generation and reduces peak turbulence levels. It is found that the shock-related noise components are most affected by the interaction of the shocks from the injectors with the primary shock structure of the jet. Increasing momentum flux ratio causes shock noise reduction until a limit where shock noise increases again. It is shown that the shock noise components and mixing noise components are reduced through fundamentally different mechanisms and maximum overall noise reduction is achieved by balancing the reduction of both components.

  13. Coherent structures in a supersonic complex nozzle

    Science.gov (United States)

    Magstadt, Andrew; Berry, Matthew; Glauser, Mark

    2016-11-01

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

  14. Accretion of Supersonic Winds on Boson Stars

    CERN Document Server

    Gracia-Linares, M

    2016-01-01

    We present the evolution of a supersonic wind interacting with a Boson Star (BS) and compare the resulting wind density profile with that of the shock cone formed when the wind is accreted by a non-rotating Black Hole (BH) of the same mass. The physical differences between these accretors are that a BS, unlike a BH has no horizon, it does not have a mechanical surface either and thus the wind is expected to trespass the BS. Despite these conditions, on the BS space-time the gas achieves a stationary flux with the gas accumulating in a high density elongated structure comparable to the shock cone formed behind a BH. The highest density resides in the center of the BS whereas in the case of the BH it is found on the downstream part of the BH near the event horizon. The maximum density of the gas is smaller in the BS than in the BH case. Our results indicate that the highest density of the wind is more similar on the BS to that on the BH when the BS has high self-interaction, when it is more compact and when the...

  15. Particle Streak Velocimetry of Supersonic Nozzle Flows

    Science.gov (United States)

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

    2016-01-01

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

  16. Supersonic collisions between two gas streams

    CERN Document Server

    Lee, H M; Ryu, D; Lee, Hyung Mok; Kang, Hyesung; Ryu, Dongsu

    1995-01-01

    A star around a massive black hole can be disrupted tidally by the gravity of the black hole. Then, its debris may form a precessing stream which may even collide with itself. In order to understand the dynamical effects of the stream-stream collision on the eventual accretion of the stellar debris onto the black hole, we have studied how gas flow behaves when the outgoing stream collides supersonically with the incoming stream. We have investigated the problem analytically with one-dimensional plane-parallel streams and numerically with more realistic three-dimensional streams. A shock formed around the contact surface converts the bulk of the orbital streaming kinetic energy into thermal energy. In three-dimensional simulations, the accumulated hot post-shock gas then expands adiabatically and drives another shock into the low density ambient region. Through this expansion, thermal energy is converted back to the kinetic energy associated with the expanding motion. Thus, in the end, only a small fraction of...

  17. Drag Force Anemometer Used in Supersonic Flow

    Science.gov (United States)

    Fralick, Gustave C.

    1998-01-01

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

  18. Supersonic Magnetic Flows in the Quiet Sun

    CERN Document Server

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

    2012-01-01

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

  19. External-Compression Supersonic Inlet Design Code

    Science.gov (United States)

    Slater, John W.

    2011-01-01

    A computer code named SUPIN has been developed to perform aerodynamic design and analysis of external-compression, supersonic inlets. The baseline set of inlets include axisymmetric pitot, two-dimensional single-duct, axisymmetric outward-turning, and two-dimensional bifurcated-duct inlets. The aerodynamic methods are based on low-fidelity analytical and numerical procedures. The geometric methods are based on planar geometry elements. SUPIN has three modes of operation: 1) generate the inlet geometry from a explicit set of geometry information, 2) size and design the inlet geometry and analyze the aerodynamic performance, and 3) compute the aerodynamic performance of a specified inlet geometry. The aerodynamic performance quantities includes inlet flow rates, total pressure recovery, and drag. The geometry output from SUPIN includes inlet dimensions, cross-sectional areas, coordinates of planar profiles, and surface grids suitable for input to grid generators for analysis by computational fluid dynamics (CFD) methods. The input data file for SUPIN and the output file from SUPIN are text (ASCII) files. The surface grid files are output as formatted Plot3D or stereolithography (STL) files. SUPIN executes in batch mode and is available as a Microsoft Windows executable and Fortran95 source code with a makefile for Linux.

  20. Instrumentation and Performance Analysis Plans for the HIFiRE Flight 2 Experiment

    Science.gov (United States)

    Gruber, Mark; Barhorst, Todd; Jackson, Kevin; Eklund, Dean; Hass, Neal; Storch, Andrea M.; Liu, Jiwen

    2009-01-01

    Supersonic combustion performance of a bi-component gaseous hydrocarbon fuel mixture is one of the primary aspects under investigation in the HIFiRE Flight 2 experiment. In-flight instrumentation and post-test analyses will be two key elements used to determine the combustion performance. Pre-flight computational fluid dynamics (CFD) analyses provide valuable information that can be used to optimize the placement of a constrained set of wall pressure instrumentation in the experiment. The simulations also allow pre-flight assessments of performance sensitivities leading to estimates of overall uncertainty in the determination of combustion efficiency. Based on the pre-flight CFD results, 128 wall pressure sensors have been located throughout the isolator/combustor flowpath to minimize the error in determining the wall pressure force at Mach 8 flight conditions. Also, sensitivity analyses show that mass capture and combustor exit stream thrust are the two primary contributors to uncertainty in combustion efficiency.

  1. Characterization of the supersonic wake of a generic space launcher

    Science.gov (United States)

    Schreyer, A.-M.; Stephan, S.; Radespiel, R.

    2017-03-01

    The wake flow of a generic axisymmetric space-launcher model is investigated experimentally for flow cases with and without propulsive jet to gain insight into the wake-flow phenomena at a supersonic stage of the flight trajectory which is especially critical with respect to dynamic loads on the structure. Measurements are performed at Mach 2.9 and a Reynolds number Re D = 1.3 × 106 based on model diameter D. The nozzle exit velocity of the jet is at Mach 2.5, and the flow is moderately underexpanded ( p e/ p ∞ = 5.7). The flow topology is described based on velocity measurements in the wake by means of particle image velocimetry and schlieren visualizations. Mean and fluctuating mass-flux profiles are obtained from hot-wire measurements, and unsteady wall-pressure measurements on the main-body base are performed simultaneously. This way, the evolution of the wake flow and its spectral content can be observed along with the footprint of this highly dynamic flow on the launcher main-body base. For the case without propulsive jet, a large separated zone is forming downstream of the main body shoulder, and the flow is reattaching further downstream on the afterbody. The afterexpanding propulsive jet (air) causes a displacement of the shear layer away from the wall, preventing the reattachment of the flow. In the spectral analysis of the baseline case, a dominant frequency around St D = 0.25 is found in the pressure-fluctuation signal at the main-body base of the launcher. This frequency is related to the shedding of the separation bubble and is less pronounced in the presence of the propulsive jet. In the shear layer itself, the spectra obtained from the hot-wire signal have a more broadband low-frequency content, which also reflects the characteristic frequency of turbulent structures convected in the shear layer, a swinging motion ( St D = 0.6), as well as the radial flapping motion of the shear layer ( St D = 0.85), respectively. Moving downstream along the

  2. Supply regimes in fisheries

    DEFF Research Database (Denmark)

    Nielsen, Max

    2006-01-01

    Supply in fisheries is traditionally known for its backward bending nature, owing to externalities in production. Such a supply regime, however, exist only for pure open access fisheries. Since most fisheries worldwide are neither pure open access, nor optimally managed, rather between the extremes......-economic supply model with mesh sizes is developed. It is found that in the presence of realistic management schemes, the supply curves are close to vertical in the relevant range. Also, the supply curve under open access with mesh size limitations is almost vertical in the relevant range, owing to constant...... recruitment. The implications are that the effects on supply following from e.g. trade liberalisation and reductions of subsidies are small in several and probably most fisheries worldwide. Keywords: backward-bending supply, regulated open access, regulated restricted access, mesh size regulation, Beverton...

  3. Observations on the non-mixed length and unsteady shock motion in a two dimensional supersonic ejector

    Science.gov (United States)

    Rao, Srisha M. V.; Jagadeesh, Gopalan

    2014-03-01

    Key features that drive the operation of a supersonic ejector are the complex gasdynamic interactions of the primary and secondary flows within a variable area duct and the phenomenon of compressible turbulent mixing between them, which have to be understood at a fundamental level. An experimental study has been carried out on the mixing characteristics of a two dimensional supersonic ejector with a supersonic primary flow (air) of Mach number 2.48 and the secondary flow (subsonic) which is induced from the ambient. The non-mixed length, which is the length within the ejector for which the primary and secondary flow remain visually distinct is used to characterize the mixing in the ejector. The operating pressures, flow rates and wall static pressures along the ejector have been measured. Two flow visualization tools have been implemented—time resolved schlieren and laser scattering flow visualization. An important contribution has been the development of in-house image processing algorithms on the MATLAB platform to detect the non-mixed length from the schlieren and laser scattering images. The ratio of mass flow rates of the secondary flow to primary flow (entrainment ratio) has been varied in a range of 0.15-0.69 for two locations of the primary nozzle in the ejector duct. Representative cases have been computed using commercial CFD tool (Fluent) to supplement the experiments. Significant outcomes of the study are—the non-mixed length quantified from the flow visualization images is observed to lie within 4.5 to 5.2 times the height of the mixing duct which is confirmed by the wall static pressure profiles. The flow through the supersonic ejector in the mixed regime is explained using corroborative evidences from different diagnostic tools. A reduction of the non-mixed length by 46.7% is observed at operating conditions when the nozzle is sufficiently overexpanded. The disturbance caused to the mixing layer due to unsteady shock-boundary layer interactions

  4. Dispersion of Own Frequency of Ion-Dipole by Supersonic Transverse Wave in Solid

    Directory of Open Access Journals (Sweden)

    Minasyan V.

    2010-10-01

    Full Text Available First, we predict an existence of transverse electromagnetic field formed by supersonic transverse wave in solid. This electromagnetic wave acquires frequency and speed of sound, and it propagates along of direction propagation of supersonic wave. We also show that own frequency of ion-dipole depends on frequency of supersonic transverse wave.

  5. Simulation of underexpanded supersonic jet flows with chemical reactions

    Directory of Open Access Journals (Sweden)

    Fu Debin

    2014-06-01

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

  6. Simulation of underexpanded supersonic jet flows with chemical reactions

    Institute of Scientific and Technical Information of China (English)

    Fu Debin; Yu Yong; Niu Qinglin

    2014-01-01

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

  7. The Turbulent Dynamo in Highly Compressible Supersonic Plasmas

    CERN Document Server

    Federrath, Christoph; Bovino, Stefano; Schleicher, Dominik R G

    2014-01-01

    The turbulent dynamo may explain the origin of cosmic magnetism. While the exponential amplification of magnetic fields has been studied for incompressible gases, little is known about dynamo action in highly-compressible, supersonic plasmas, such as the interstellar medium of galaxies and the early Universe. Here we perform the first quantitative comparison of theoretical models of the dynamo growth rate and saturation level with three-dimensional magnetohydrodynamical simulations of supersonic turbulence with grid resolutions of up to 1024^3 cells. We obtain numerical convergence and find that dynamo action occurs for both low and high magnetic Prandtl numbers Pm = nu/eta = 0.1-10 (the ratio of viscous to magnetic dissipation), which had so far only been seen for Pm >= 1 in supersonic turbulence. We measure the critical magnetic Reynolds number, Rm_crit = 129 (+43, -31), showing that the compressible dynamo is almost as efficient as in incompressible gas. Considering the physical conditions of the present a...

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

    Energy Technology Data Exchange (ETDEWEB)

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

    2001-07-01

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

  9. Dynamics and density distributions in a capillary-discharge waveguide with an embedded supersonic jet

    Energy Technology Data Exchange (ETDEWEB)

    Matlis, N. H., E-mail: nmatlis@gmail.com; Gonsalves, A. J.; Steinke, S.; Tilborg, J. van; Shaw, B.; Mittelberger, D. E.; Geddes, C. G. R. [Lawrence Berkeley National Laboratory, Berkeley, California 94720 (United States); Matlis, E. H. [Department of Aerospace and Mechanical Engineering, University of Notre Dame, Notre Dame, Indiana 46556 (United States); Leemans, W. P. [Lawrence Berkeley National Laboratory, Berkeley, California 94720 (United States); Department of Physics, University of California, Berkeley, California 94720 (United States)

    2015-11-28

    We present an analysis of the gas dynamics and density distributions within a capillary-discharge waveguide with an embedded supersonic jet. This device provides a target for a laser plasma accelerator which uses longitudinal structuring of the gas-density profile to enable control of electron trapping and acceleration. The functionality of the device depends sensitively on the details of the density profile, which are determined by the interaction between the pulsed gas in the jet and the continuously-flowing gas in the capillary. These dynamics are captured by spatially resolving recombination light from several emission lines of the plasma as a function of the delay between the jet and the discharge. We provide a phenomenological description of the gas dynamics as well as a quantitative evaluation of the density evolution. In particular, we show that the pressure difference between the jet and the capillary defines three regimes of operation with qualitatively different longitudinal density profiles and show that jet timing provides a sensitive method for tuning between these regimes.

  10. X-1 in flight

    Science.gov (United States)

    1947-01-01

    The Bell Aircraft Corporation X-1-1 (#46-062) in flight. The shock wave pattern in the exhaust plume is visible. The X-1 series aircraft were air-launched from a modified Boeing B-29 or a B-50 Superfortress bombers. The X-1-1 was painted a bright orange by Bell Aircraft. It was thought that the aircraft would be more visable to those doing the tracking during a flight. When NACA received the airplanes they were painted white, which was an easier color to find in the skies over Muroc Air Field in California. This particular craft was nicknamed 'Glamorous Glennis' by Chuck Yeager in honor of his wife, and is now on permanent display in the Smithsonian Institution's National Air and Space Museum in Washington, DC. There were five versions of the Bell X-1 rocket-powered research aircraft that flew at the NACA High-Speed Flight Research Station, Edwards, California. The bullet-shaped X-1 aircraft were built by Bell Aircraft Corporation, Buffalo, N.Y. for the U.S. Army Air Forces (after 1947, U.S. Air Force) and the National Advisory Committee for Aeronautics (NACA). The X-1 Program was originally designated the XS-1 for EXperimental Sonic. The X-1's mission was to investigate the transonic speed range (speeds from just below to just above the speed of sound) and, if possible, to break the 'sound barrier.' Three different X-1s were built and designated: X-1-1, X-1-2 (later modified to become the X-1E), and X-1-3. The basic X-1 aircraft were flown by a large number of different pilots from 1946 to 1951. The X-1 Program not only proved that humans could go beyond the speed of sound, it reinforced the understanding that technological barriers could be overcome. The X-1s pioneered many structural and aerodynamic advances including extremely thin, yet extremely strong wing sections; supersonic fuselage configurations; control system requirements; powerplant compatibility; and cockpit environments. The X-1 aircraft were the first transonic-capable aircraft to use an all

  11. Resilience of river flow regimes.

    Science.gov (United States)

    Botter, Gianluca; Basso, Stefano; Rodriguez-Iturbe, Ignacio; Rinaldo, Andrea

    2013-08-06

    Landscape and climate alterations foreshadow global-scale shifts of river flow regimes. However, a theory that identifies the range of foreseen impacts on streamflows resulting from inhomogeneous forcings and sensitivity gradients across diverse regimes is lacking. Here, we derive a measurable index embedding climate and landscape attributes (the ratio of the mean interarrival of streamflow-producing rainfall events and the mean catchment response time) that discriminates erratic regimes with enhanced intraseasonal streamflow variability from persistent regimes endowed with regular flow patterns. Theoretical and empirical data show that erratic hydrological regimes typical of rivers with low mean discharges are resilient in that they hold a reduced sensitivity to climate fluctuations. The distinction between erratic and persistent regimes provides a robust framework for characterizing the hydrology of freshwater ecosystems and improving water management strategies in times of global change.

  12. Supersonic stall flutter of high-speed fans

    Science.gov (United States)

    Adamczyk, J. J.; Stevans, W.; Jutras, R.

    1981-01-01

    An analytical model is proposed for predicting the onset of supersonic stall bending flutter in high-speed rotors. The analysis is based on a modified two-dimensional, compressible, unsteady actuator disk theory. The stability boundary predicted by the analysis is shown to be in good agreement with the measured boundary of a high speed fan. The prediction that the flutter mode would be a forward traveling wave sensitive to wheel speed and aerodynamic loading is confirmed by experimental measurements. In addition, the analysis shows that reduced frequency and dynamic head also play a significant role in establishing the supersonic stall bending flutter boundary of an unshrouded fan.

  13. The impact of emerging technologies on an advanced supersonic transport

    Science.gov (United States)

    Driver, C.; Maglieri, D. J.

    1986-01-01

    The effects of advances in propulsion systems, structure and materials, aerodynamics, and systems on the design and development of supersonic transport aircraft are analyzed. Efficient propulsion systems with variable-cycle engines provide the basis for improved propulsion systems; the propulsion efficienies of supersonic and subsonic engines are compared. Material advances consist of long-life damage-tolerant structures, advanced material development, aeroelastic tailoring, and low-cost fabrication. Improvements in the areas of aerodynamics and systems are examined. The environmental problems caused by engine emissions, airport noise, and sonic boom are studied. The characteristics of the aircraft designed to include these technical advances are described.

  14. Continuing Validation of Computational Fluid Dynamics for Supersonic Retropropulsion

    Science.gov (United States)

    Schauerhamer, Daniel Guy; Trumble, Kerry A.; Kleb, Bil; Carlson, Jan-Renee; Edquist, Karl T.

    2011-01-01

    A large step in the validation of Computational Fluid Dynamics (CFD) for Supersonic Retropropulsion (SRP) is shown through the comparison of three Navier-Stokes solvers (DPLR, FUN3D, and OVERFLOW) and wind tunnel test results. The test was designed specifically for CFD validation and was conducted in the Langley supersonic 4 x4 Unitary Plan Wind Tunnel and includes variations in the number of nozzles, Mach and Reynolds numbers, thrust coefficient, and angles of orientation. Code-to-code and code-to-test comparisons are encouraging and possible error sources are discussed.

  15. Subsonic and Supersonic Jet Noise Calculations Using PSE and DNS

    Science.gov (United States)

    Balakumar, P.; Owis, Farouk

    1999-01-01

    Noise radiated from a supersonic jet is computed using the Parabolized Stability Equations (PSE) method. The evolution of the instability waves inside the jet is computed using the PSE method and the noise radiated to the far field from these waves is calculated by solving the wave equation using the Fourier transform method. We performed the computations for a cold supersonic jet of Mach number 2.1 which is excited by disturbances with Strouhal numbers St=.2 and .4 and the azimuthal wavenumber m=l. Good agreement in the sound pressure level are observed between the computed and the measured (Troutt and McLaughlin 1980) results.

  16. 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.

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

    Energy Technology Data Exchange (ETDEWEB)

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

    1980-07-01

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

  18. DAST Being Calibrated for Flight in Hangar

    Science.gov (United States)

    1982-01-01

    DAST-2, a modified BQM-34 Firebee II drone, undergoes calibration in a hangar at the NASA Dryden Flight Research Center. After the crash of the first DAST vehicle, project personnel fitted a second Firebee II (serial # 72-1558) with the rebuilt ARW-1 (ARW-1R) wing. The DAST-2 made a captive flight aboard the B-52 on October 29, 1982, followed by a free flight on November 3, 1982. During January and February of 1983, three launch attempts from the B-52 had to be aborted due to various problems. Following this, the project changed the launch aircraft to a DC-130A. Two captive flights occurred in May 1983. The first launch attempt from the DC-130 took place on June 1, 1983. The mothership released the DAST-2, but the recovery system immediately fired without being commanded. The parachute then disconnected from the vehicle, and the DAST-2 crashed into a farm field near Harper Dry Lake. Wags called this the 'Alfalfa Field Impact Test.' These are the image contact sheets for each image resolution of the NASA Dryden Drones for Aerodynamic and Structural Testing (DAST) Photo Gallery. From 1977 to 1983, the Dryden Flight Research Center, Edwards, California, (under two different names) conducted the DAST Program as a high-risk flight experiment using a ground-controlled, pilotless aircraft. Described by NASA engineers as a 'wind tunnel in the sky,' the DAST was a specially modified Teledyne-Ryan BQM-34E/F Firebee II supersonic target drone that was flown to validate theoretical predictions under actual flight conditions in a joint project with the Langley Research Center, Hampton, Virginia. The DAST Program merged advances in electronic remote control systems with advances in airplane design. Drones (remotely controlled, missile-like vehicles initially developed to serve as gunnery targets) had been deployed successfully during the Vietnamese conflict as reconnaissance aircraft. After the war, the energy crisis of the 1970s led NASA to seek new ways to cut fuel use and

  19. DAST in Flight Showing Diverging Wingtip Oscillations

    Science.gov (United States)

    1980-01-01

    Two BQM-34 Firebee II drones were modified with supercritical airfoils, called the Aeroelastic Research Wing (ARW), for the Drones for Aerodynamic and Structural Testing (DAST) program, which ran from 1977 to 1983. In this view of DAST-1 (Serial # 72-1557), taken on June 12, 1980, severe wingtip flutter is visible. Moments later, the right wing failed catastrophically and the vehicle crashed near Cuddeback Dry Lake. Before the drone was lost, it had made two captive and two free flights. Its first free flight, on October 2, 1979, was cut short by an uplink receiver failure. The drone was caught in midair by an HH-3 helicopter. The second free flight, on March 12, 1980, was successful, ending in a midair recovery. The third free flight, made on June 12, was to expand the flutter envelope. All of these missions launched from the NASA B-52. From 1977 to 1983, the Dryden Flight Research Center, Edwards, California, (under two different names) conducted the DAST Program as a high-risk flight experiment using a ground-controlled, pilotless aircraft. Described by NASA engineers as a 'wind tunnel in the sky,' the DAST was a specially modified Teledyne-Ryan BQM-34E/F Firebee II supersonic target drone that was flown to validate theoretical predictions under actual flight conditions in a joint project with the Langley Research Center, Hampton, Virginia. The DAST Program merged advances in electronic remote control systems with advances in airplane design. Drones (remotely controlled, missile-like vehicles initially developed to serve as gunnery targets) had been deployed successfully during the Vietnamese conflict as reconnaissance aircraft. After the war, the energy crisis of the 1970s led NASA to seek new ways to cut fuel use and improve airplane efficiency. The DAST Program's drones provided an economical, fuel-conscious method for conducting in-flight experiments from a remote ground site. DAST explored the technology required to build wing structures with less than

  20. A Grid Sourcing and Adaptation Study Using Unstructured Grids for Supersonic Boom Prediction

    Science.gov (United States)

    Carter, Melissa B.; Deere, Karen A.

    2008-01-01

    NASA created the Supersonics Project as part of the NASA Fundamental Aeronautics Program to advance technology that will make a supersonic flight over land viable. Computational flow solvers have lacked the ability to accurately predict sonic boom from the near to far field. The focus of this investigation was to establish gridding and adaptation techniques to predict near-to-mid-field (sources along the body the aircraft, far field sourcing and far field boundaries. The study then examined several techniques for grid adaptation. During the course of the study, volume sourcing was introduced as a new way to source grids using the grid generation code VGRID. Two different methods of using the volume sources were examined. The first method, based on manual insertion of the numerous volume sources, made great improvements in the prediction capability of USM3D for boom signatures. The second method (SSGRID), which uses an a priori adaptation approach to stretch and shear the original unstructured grid to align the grid and pressure waves, showed similar results with a more automated approach. Due to SSGRID s results and ease of use, the rest of the study focused on developing a best practice using SSGRID. The best practice created by this study for boom predictions using the CFD code USM3D involved: 1) creating a small cylindrical outer boundary either 1 or 2 body lengths in diameter (depending on how far below the aircraft the boom prediction is required), 2) using a single volume source under the aircraft, and 3) using SSGRID to stretch and shear the grid to the desired length.

  1. Flight Test Results for the F-16XL With a Digital Flight Control System

    Science.gov (United States)

    Stachowiak, Susan J.; Bosworth, John T.

    2004-01-01

    In the early 1980s, two F-16 airplanes were modified to extend the fuselage length and incorporate a large area delta wing planform. These two airplanes, designated the F-16XL, were designed by the General Dynamics Corporation (now Lockheed Martin Tactical Aircraft Systems) (Fort Worth, Texas) and were prototypes for a derivative fighter evaluation program conducted by the United States Air Force. Although the concept was never put into production, the F-16XL prototypes provided a unique planform for testing concepts in support of future high-speed supersonic transport aircraft. To extend the capabilities of this testbed vehicle the F-16XL ship 1 aircraft was upgraded with a digital flight control system. The added flexibility of a digital flight control system increases the versatility of this airplane as a testbed for aerodynamic research and investigation of advanced technologies. This report presents the handling qualities flight test results covering the envelope expansion of the F-16XL with the digital flight control system.

  2. Unitary Housing Regimes in Transition

    DEFF Research Database (Denmark)

    Bengtsson, Bo; Jensen, Lotte

    2013-01-01

    to the Danish and Swedish housing regimes are analysed and the responses and outcomes in terms of policy change and/or institutional continuity (path dependence) are compared. Overall, the more decentralized Danish housing regime seems to have resisted pressures for change and retrenchment better so far than...

  3. Regime shifts in resource management

    NARCIS (Netherlands)

    de Zeeuw, A.J.

    2014-01-01

    Resource management has to take account of the possibility of tipping points and regime shifts in ecological systems that provide the resources. This article focuses on the typical model of regime shifts in the ecological literature and analyzes optimal management and common-property issues when tra

  4. Examination Regimes and Student Achievement

    Science.gov (United States)

    Cosentino de Cohen, Clemencia

    2010-01-01

    Examination regimes at the end of secondary school vary greatly intra- and cross-nationally, and in recent years have undergone important reforms often geared towards increasing student achievement. This research presents a comparative analysis of the relationship between examination regimes and student achievement in the OECD. Using a micro…

  5. 'Regime shopping' across (blurring) boundaries

    NARCIS (Netherlands)

    Houwerzijl, M.S.; Evju, Stein

    2014-01-01

    This book chapter identifies and explores the (blurring) boundaries between the legal regimes for labour mobility across the EU. In the context of - what is sometimes called - 'regime shopping' a close look is taken into the law on freedom of movement within the EU. Several categories of transnation

  6. 'Regime shopping' across (blurring) boundaries

    NARCIS (Netherlands)

    Houwerzijl, M.S.; Evju, Stein

    2014-01-01

    This book chapter identifies and explores the (blurring) boundaries between the legal regimes for labour mobility across the EU. In the context of - what is sometimes called - 'regime shopping' a close look is taken into the law on freedom of movement within the EU. Several categories of

  7. Research of low boom and low drag supersonic aircraft design

    Institute of Scientific and Technical Information of China (English)

    Feng Xiaoqiang; Li Zhanke; Song Bifeng

    2014-01-01

    Sonic boom reduction will be an issue of utmost importance in future supersonic trans-port, due to strong regulations on acoustic nuisance. The paper describes a new multi-objective optimization method for supersonic aircraft design. The method is developed by coupling Seebass-George-Darden (SGD) inverse design method and multi-objective genetic algorithm. Based on the method, different codes are developed. Using a computational architecture, a concep-tual supersonic aircraft design environment (CSADE) is constructed. The architecture of CSADE includes inner optimization level and out optimization level. The low boom configuration is gener-ated in inner optimization level by matching the target equivalent area distribution and actual equivalent area distribution. And low boom/low drag configuration is generated in outer optimiza-tion level by using NSGA-II multi-objective genetic algorithm to optimize the control parameters of SGD method and aircraft shape. Two objective functions, low sonic boom and low wave drag, are considered in CSADE. Physically reasonable Pareto solutions are obtained from the present optimization. Some supersonic aircraft configurations are selected from Pareto front and the optimization results indicate that the swept forward wing configuration has benefits in both sonic boom reduction and wave drag reduction. The results are validated by using computational fluid dynamics (CFD) analysis.

  8. Titanium honeycomb structure. [for supersonic aircraft wing structure

    Science.gov (United States)

    Davis, R. A.; Elrod, S. D.; Lovell, D. T.

    1972-01-01

    A brazed titanium honeycomb sandwich system for supersonic transport wing cover panels provides the most efficient structure spanwise, chordwise, and loadwise. Flutter testing shows that high wing stiffness is most efficient in a sandwich structure. This structure also provides good thermal insulation if liquid fuel is carried in direct contact with the wing structure in integral fuel tanks.

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

    Directory of Open Access Journals (Sweden)

    Tropina, A. A.

    2013-06-01

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

  10. 76 FR 30231 - Civil Supersonic Aircraft Panel Discussion

    Science.gov (United States)

    2011-05-24

    ... for attendees. The purpose of the meeting is to raise public awareness of the continuing technological... joint meeting of the 159th Acoustical Society of America and NOISE-CON 2010 in Baltimore, Maryland 21202. The purpose of these meetings is to raise public awareness on advances in supersonic technology,...

  11. Multiresolution analysis of density fluctuation in supersonic mixing layer

    Institute of Scientific and Technical Information of China (English)

    2010-01-01

    Due to the difficulties in measuring supersonic density field, the multiresolution analysis of supersonic mixing layer based on experimental images is still a formidable challenge. By utilizing the recently developed nanoparticle based planar laser scattering method, the density field of a supersonic mixing layer was measured at high spatiotemporal resolution. According to the dynamic behavior of coherent structures, the multiresolution characteristics of density fluctuation signals and density field images were studied based on Taylor’s hypothesis of space-time conversion and wavelet analysis. The wavelet coefficients reflect the characteristics of density fluctuation signals at different scales, and the detailed coefficients reflect the differences of approximation at adjacent levels. The density fluctuation signals of supersonic mixing layer differ from the periodic sine signal and exhibit similarity to the fractal Koch signal. The similarity at different scales reveals the fractal characteristic of mixing layer flowfield. The two-dimensional wavelet decomposition and reconstruction of density field images extract the approximate and detailed signals at different scales, which effectively resolve the characteristic structures of the flowfield at different scales.

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

    Institute of Scientific and Technical Information of China (English)

    LEE; ChunHian

    2010-01-01

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

  13. Toward Active Control of Noise from Hot Supersonic Jets

    Science.gov (United States)

    2013-02-15

    applied a double divergence directly to the incompressible Reynolds stress giving Ö U’UI dxgJ = -£ijk(sijUJk + ryWfc). (1) This neglected...SUPERSONIC JETS | QUARTERLY RPT. 6 ^ EXPERIMENTAL FACILITY j^i;r\\’ii Mo/ P I V • Page 6 • Prev • Wart • Last • Full Screen • Close

  14. Research of low boom and low drag supersonic aircraft design

    Directory of Open Access Journals (Sweden)

    Feng Xiaoqiang

    2014-06-01

    Full Text Available Sonic boom reduction will be an issue of utmost importance in future supersonic transport, due to strong regulations on acoustic nuisance. The paper describes a new multi-objective optimization method for supersonic aircraft design. The method is developed by coupling Seebass–George–Darden (SGD inverse design method and multi-objective genetic algorithm. Based on the method, different codes are developed. Using a computational architecture, a conceptual supersonic aircraft design environment (CSADE is constructed. The architecture of CSADE includes inner optimization level and out optimization level. The low boom configuration is generated in inner optimization level by matching the target equivalent area distribution and actual equivalent area distribution. And low boom/low drag configuration is generated in outer optimization level by using NSGA-II multi-objective genetic algorithm to optimize the control parameters of SGD method and aircraft shape. Two objective functions, low sonic boom and low wave drag, are considered in CSADE. Physically reasonable Pareto solutions are obtained from the present optimization. Some supersonic aircraft configurations are selected from Pareto front and the optimization results indicate that the swept forward wing configuration has benefits in both sonic boom reduction and wave drag reduction. The results are validated by using computational fluid dynamics (CFD analysis.

  15. In-flight spectrometers status and new developments

    CERN Document Server

    Geissel, H; Weick, H

    2002-01-01

    In-flight spectrometers have been successfully used for the investigation of exotic nuclei from low energies near the Coulomb barrier up to the A GeV regime. The in-flight method takes advantage of the reaction kinematics to efficiently separate short-lived nuclei at the limits of stability down to a sensitivity of single atoms. Modern in-flight separators are combined with high-resolution devices such as electromagnetic spectrometers, storage-cooler rings, and ion traps. Atomic interaction in matter is a versatile tool to tailor the phase space of nuclear reaction products for efficient separation in flight.

  16. LES Modeling of Supersonic Combustion at SCRAMJET Conditions

    Science.gov (United States)

    Vane, Zachary; Lacaze, Guilhem; Oefelein, Joseph

    2016-11-01

    Results from a series of large-eddy simulations (LES) of the Hypersonic International Flight Research Experiment (HIFiRE) are examined with emphasis placed on the coupled performance of the wall and combustion models. The test case of interest corresponds to the geometry and conditions found in the ground based experiments performed in the HIFiRE Direct Connect Rig (HDCR) in dual-mode operation. In these calculations, the turbulence and mixing characteristics of the high Reynolds number turbulent boundary layer with multi-species fuel injection are analyzed using a simplified chemical model and combustion closure to predict the heat release measured experimentally. These simulations are then used to identify different flame regimes in the combustor section. Concurrently, the performance of an equilibrium wall-model is evaluated in the vicinity of the fuel injectors and in the flame-holding cavity where regions of boundary layer and thermochemical non-equilibrium are present. Support for this research was provided by the Defense Advanced Research Projects Agency (DARPA).

  17. Flight simulator for hypersonic vehicle and a study of NASP handling qualities

    Science.gov (United States)

    Ntuen, Celestine A.; Park, Eui H.; Deeb, Joseph M.; Kim, Jung H.

    1992-01-01

    The research goal of the Human-Machine Systems Engineering Group was to study the existing handling quality studies in aircraft with sonic to supersonic speeds and power in order to understand information requirements needed for a hypersonic vehicle flight simulator. This goal falls within the NASA task statements: (1) develop flight simulator for hypersonic vehicle; (2) study NASP handling qualities; and (3) study effects of flexibility on handling qualities and on control system performance. Following the above statement of work, the group has developed three research strategies. These are: (1) to study existing handling quality studies and the associated aircraft and develop flight simulation data characterization; (2) to develop a profile for flight simulation data acquisition based on objective statement no. 1 above; and (3) to develop a simulator and an embedded expert system platform which can be used in handling quality experiments for hypersonic aircraft/flight simulation training.

  18. The discrete regime of flame propagation

    Science.gov (United States)

    Tang, Francois-David; Goroshin, Samuel; Higgins, Andrew

    The propagation of laminar dust flames in iron dust clouds was studied in a low-gravity envi-ronment on-board a parabolic flight aircraft. The elimination of buoyancy-induced convection and particle settling permitted measurements of fundamental combustion parameters such as the burning velocity and the flame quenching distance over a wide range of particle sizes and in different gaseous mixtures. The discrete regime of flame propagation was observed by substitut-ing nitrogen present in air with xenon, an inert gas with a significantly lower heat conductivity. Flame propagation in the discrete regime is controlled by the heat transfer between neighbor-ing particles, rather than by the particle burning rate used by traditional continuum models of heterogeneous flames. The propagation mechanism of discrete flames depends on the spa-tial distribution of particles, and thus such flames are strongly influenced by local fluctuations in the fuel concentration. Constant pressure laminar dust flames were observed inside 70 cm long, 5 cm diameter Pyrex tubes. Equally-spaced plate assemblies forming rectangular chan-nels were placed inside each tube to determine the quenching distance defined as the minimum channel width through which a flame can successfully propagate. High-speed video cameras were used to measure the flame speed and a fiber optic spectrometer was used to measure the flame temperature. Experimental results were compared with predictions obtained from a numerical model of a three-dimensional flame developed to capture both the discrete nature and the random distribution of particles in the flame. Though good qualitative agreement was obtained between model predictions and experimental observations, residual g-jitters and the short reduced-gravity periods prevented further investigations of propagation limits in the dis-crete regime. The full exploration of the discrete flame phenomenon would require high-quality, long duration reduced gravity environment

  19. Effect of emerging technology on a convertible, business/interceptor, supersonic-cruise jet

    Science.gov (United States)

    Beissner, F. L., Jr.; Lovell, W. A.; Robins, A. W.; Swanson, E. E.

    1986-01-01

    This study was initiated to assess the feasibility of an eight-passenger, supersonic-cruise long range business jet aircraft that could be converted into a military missile carrying interceptor. The baseline passenger version has a flight crew of two with cabin space for four rows of two passenger seats plus baggage and lavatory room in the aft cabin. The ramp weight is 61,600 pounds with an internal fuel capacity of 30,904 pounds. Utilizing an improved version of a current technology low-bypass ratio turbofan engine, range is 3,622 nautical miles at Mach 2.0 cruise and standard day operating conditions. Balanced field takeoff distance is 6,600 feet and landing distance is 5,170 feet at 44,737 pounds. The passenger section from aft of the flight crew station to the aft pressure bulkhead in the cabin was modified for the interceptor version. Bomb bay type doors were added and volume is sufficient for four advanced air-to-air missiles mounted on a rotary launcher. Missile volume was based on a Phoenix type missile with a weight of 910 pounds per missile for a total payload weight of 3,640 pounds. Structural and equipment weights were adjusted and result in a ramp weight of 63,246 pounds with a fuel load of 30,938 pounds. Based on a typical intercept mission flight profile, the resulting radius is 1,609 nautical miles at a cruise Mach number of 2.0.

  20. SR-71 flight

    Science.gov (United States)

    1990-01-01

    The movie clip shown here runs about 13 seconds and shows an air-to-air shot of the front of the SR-71 aircraft and a head-on view of it coming in for a landing. Two SR-71A aircraft on loan from the U.S. Air Force have been used for high-speed, high-altitude research at the NASA Dryden Flight Research Center, Edwards, California, since 1991. One of them was later returned to the Air Force. A third SR-71 on loan from the Air Force is an SR-71B used for training but not for flight research. Developed for the U.S. Air Force as reconnaissance aircraft more than 30 years ago, SR-71 aircraft are still the world's fastest and highest-flying production aircraft. These aircraft can fly more than 2200 miles per hour (Mach 3+ or more than three times the speed of sound) and at altitudes of over 85,000 feet. This operating environment makes the aircraft excellent platforms to carry out research and experiments in a variety of areas--aerodynamics, propulsion, structures, thermal protection materials, high-speed and high-temperature instrumentation, atmospheric studies, and sonic-boom characterization. Data from the SR-71 high-speed research program may be used to aid designers of future supersonic or hypersonic aircraft and propulsion systems, including a possible high-speed civil transport. The SR-71 program at Dryden has been part of the NASA overall high-speed aeronautical research program, and projects have involved other NASA research centers, other government agencies, universities, and commercial firms. One of the first major experiments to be flown in the NASA SR-71 program was a laser air-data collection system. This system used laser light instead of air pressure to produce airspeed and attitude reference data such as angle of attack and angle of sideslip. These data are normally obtained with small tubes and vanes extending into the air stream, or from tubes with flush openings on the aircraft outer skin. The flights provided information on the presence of

  1. Sonic Boom Research at NASA Dryden: Objectives and Flight Results from the Lift and Nozzle Change Effects on Tail Shock (LaNCETS) Project

    Science.gov (United States)

    Moes, Timothy R.

    2009-01-01

    The principal objective of the Supersonics Project is to develop and validate multidisciplinary physics-based predictive design, analysis and optimization capabilities for supersonic vehicles. For aircraft, the focus will be on eliminating the efficiency, environmental and performance barriers to practical supersonic flight. Previous flight projects found that a shaped sonic boom could propagate all the way to the ground (F-5 SSBD experiment) and validated design tools for forebody shape modifications (F-5 SSBD and Quiet Spike experiments). The current project, Lift and Nozzle Change Effects on Tail Shock (LaNCETS) seeks to obtain flight data to develop and validate design tools for low-boom tail shock modifications. Attempts will be made to alter the shock structure of NASA's NF-15B TN/837 by changing the lift distribution by biasing the canard positions, changing the plume shape by under- and over-expanding the nozzles, and changing the plume shape using thrust vectoring. Additional efforts will measure resulting shocks with a probing aircraft (F-15B TN/836) and use the results to validate and update predictive tools. Preliminary flight results are presented and are available to provide truth data for developing and validating the CFD tools required to design low-boom supersonic aircraft.

  2. Optimization of Mass Bleed Control for Base Drag Reduction of Supersonic Flight Bodies

    Institute of Scientific and Technical Information of China (English)

    Y.-K.Lee; H.-D.Kim

    2006-01-01

    The minimization of base drag using mass bleed control is examined in consideration of various base to orifice exit area ratios for a body of revolution in the Mach 2.47 freestream. Axisymmtric, compressible, mass-averaged Navier-Stokes equations are solved using the standard k-ω turbulence model, a fully implicit finite volume scheme, and a second order upwind scheme. Base flow characteristics are explained regarding the base configuration as well as the injection parameter which is defined as the mass flow rate of bleed jet non-dimensionalized by the product of the base area and freestream mass flux. The results obtained through the present study show that for a smaller base area, the optimum mass bleed condition leading to minimum base drag occurs at relatively larger mass bleed, and a larger orifice exit can offer better drag control.

  3. Locomotor problems of supersonic aviation and astronautics.

    Science.gov (United States)

    Remes, P

    1989-04-01

    Modern high-speed aviation and space flight are fraught with many problems and require a high standard of health and fitness. Those responsible for the health of pilots must appreciate the importance of early diagnosis even before symptoms appear. This is particularly true in terms of preventing spinal injuries where even a single Schmorl's node may make a pilot unfit for high-speed flying. Spinal fractures are frequent during emergency ejection and landing. Helicopter crews are particularly prone to spinal disc degeneration due to vibration. By effective lowering of vibration by changes in the seats, a reduction in such lesions is possible. The osteoporosis and muscle atrophy occurring among astronauts subjected to prolonged weightlessness can be prevented by regular physical exercises.

  4. Experimental and Numerical Studies of Vitiated Air Effects on Hydrogen-fueled Supersonic Combustor Performance

    Institute of Scientific and Technical Information of China (English)

    LUO Feiteng; SONG Wenyan; ZHANG Zhiqiang; LI Weiqiang; LI Jianping

    2012-01-01

    This paper deals with the vitiation effects of test air on the scramjet performance in the ground combustion heated facilities.The primary goal is to evaluate the effects of H2O and CO2,the two major vitiated species generated by combustion heater,on hydrogen-fueled supersonic combustor performance with experimental and numerical approaches.The comparative experiments in the clean air and vitiated air are conducted by using the resistance heated direct-connected facility,with the typical Mach 4 flight conditions simulated.The H2O and CO2 species with accurately controlled contents are added to the high enthalpy clean air from resistance heater,to synthesize the vitiated air of a combustion-type heater.Typically,the contents of H2O species can be varied within the range of 3.5%-30o% by mole,and 3.0%-10% for CO2 species.The total temperature,total pressure,Mach number and O2 mole fraction at the combustor entrance are well-matched between the clean air and vitiated air.The combustion experiments are completed at the fuel equivalence ratios of 0.53 and 0.42 respectively.Furthermore,three-dimensional (3D) reacting flow simulations of combustor towpath are performed to provide insight into flow field structures and combustion chemistry details that cannot resolved by experimental instruments available.Finally,the experimental data,combined with computational results,are employed to analyze the effects of H2O and CO2 vitiated air on supersonic combustion characteristics and performance.It is concluded that H2O and CO2 contaminants can significantly inhibit the combustion induced pressure rise measured from combustor wall,and the pressure profile decreases with the increasing H2O and CO2 contents in nonlinear trend;simulation results agree well with experimental data and the overall vitiation effects are captured; direct extrapolation of the results from vitiated air to predict the performance of actual flight conditions could result in over-fueling the combustor

  5. The Choice of Monetary Regime

    DEFF Research Database (Denmark)

    Østrup, Finn

    , a comparisonbetween monetary regimes suggests that welfare is highest under nominalincome targeting where the nominal income target is determined to bring aboutprice stability.Keywords: Monetary regimes; fiscal policy; monetary non-neutrality.JEL classicification: E42, E61, E62.......The article examines how government spending is determined in a closedeconomy where the nominal wage is pre-set through contracts and the wage settershave perfect foresight regarding subsequent policy decisions. The monetaryregime affects government spending because: (i) with a pre-set nominal wage......, agiven change in government spending has different effects on employment andinflation under different monetary regimes, and (ii) the authorities' inclinationto expand government spending is affected by the inflation rate which dependson the monetary regime. If the costs related to inflation are high...

  6. THE ETHIOPIAN ENVIRONMENTAL REGIME VERSUS ...

    African Journals Online (AJOL)

    Haramaya Law Review ... ozone layer and climate change regimes, among others, to succeed. Id. ... international act dealing with general aspects of air pollution. ..... environmental and developmental decisions that affect their interests or the.

  7. Experimental characterization of a transition from collisionless to collisional interaction between head-on-merging supersonic plasma jets

    CERN Document Server

    Moser, A L

    2014-01-01

    We present results from experiments on the head-on merging of two supersonic plasma jets in an initially collisionless regime for the counter-streaming ions [A. L. Moser & S. C. Hsu, Phys. Plasmas, submitted (2014)]. The plasma jets are of either an argon/impurity or hydrogen/impurity mixture and are produced by pulsed-power-driven railguns. Based on time- and space-resolved fast-imaging, multi-chord interferometry, and survey-spectroscopy measurements of the overlapping region between the merging jets, we observe that the jets initially interpenetrate, consistent with calculated inter-jet ion collision lengths, which are long. As the jets interpenetrate, a rising mean-charge state causes a rapid decrease in the inter-jet ion collision length. Finally, the interaction becomes collisional and the jets stagnate, eventually producing structures consistent with collisional shocks. These experimental observations can aid in the validation of plasma collisionality and ionization models for plasmas with complex ...

  8. Techniques for determining propulsion system forces for accurate high speed vehicle drag measurements in flight

    Science.gov (United States)

    Arnaiz, H. H.

    1975-01-01

    As part of a NASA program to evaluate current methods of predicting the performance of large, supersonic airplanes, the drag of the XB-70 airplane was measured accurately in flight at Mach numbers from 0.75 to 2.5. This paper describes the techniques used to determine engine net thrust and the drag forces charged to the propulsion system that were required for the in-flight drag measurements. The accuracy of the measurements and the application of the measurement techniques to aircraft with different propulsion systems are discussed. Examples of results obtained for the XB-70 airplane are presented.

  9. Passive Acoustic Radar for Detecting Supersonic Cruise Missile

    Institute of Scientific and Technical Information of China (English)

    XIAO Feng; XIAO Hui

    2005-01-01

    A Passive Acoustic Radar is presented as a necessary complement to electromagnetic wave radar, which will be expected to be an effective means for detecting cruise missiles. Acoustic characteristics of supersonic flying projectiles with diverse shapes are expounded via experiment. It is pointed out that simulation experiment could be implemented using bullet or shell instead of cruise missile. Based on theoretical analysis and experiment, the "acoustic fingerprint" character of cruise missile is illustrated to identify it in a strong noise environment. After establishing a locating mathematical model,the technique of acoustic embattling is utilized to resolve a problem of confirming the time of early-warning, considering the fact that velocity of sound is much slower than that of light. Thereby, a whole system of passive acoustic radar for detecting supersonic cruise missile is formed.

  10. Ethylene tetrafluoroethylene nanofibers prepared by CO2 laser supersonic drawing

    Directory of Open Access Journals (Sweden)

    A. Suzuki

    2013-06-01

    Full Text Available Ethylene tetrafluoroethylene (ETFE nanofibers were prepared by carbon dioxide (CO2 laser irradiation of asspun ETFE fibers with four different melt flow rates (MFRs in a supersonic jet that was generated by blowing air into a vacuum chamber through the fiber injection orifice. The drawability and superstructure of fibers produced by CO2 laser supersonic drawing depend on the laser power, the chamber pressure, the fiber injection speed, and the MFR. Nanofibers obtained using a laser power of 20 W, a chamber pressure of 20 kPa, and an MFR of 308 g•10 min–1 had an average diameter of 0.303 µm and a degree of crystallinity of 54%.

  11. Features of Ignition and Stable Combustion in Supersonic Combustor

    Science.gov (United States)

    Goldfeld, M.; Starov, A.; Timofeev, K.

    2009-01-01

    Present paper describes the results of experimental investigations of the supersonic combustor with entrance Mach numbers from 2 to 4 at static pressure from 0.8 to 2.5 bars, total temperature from 2000K to 3000K. Hydrogen and kerosene were used as fuel. The conditions, under which the self-ignition and intensive combustion of the fuel realized were found. Position of ignition area in the channel was determined and features of flame propagation in the channel presented. A possibility to ensure an efficient combustion of hydrogen and kerosene at a high supersonic flow velocity at the combustor entrance without special throttling and/or pseudo-shock introduction was shown. Analysis of applicability of existing methods of criterion descriptions of conditions of self-ignition and extinction of combustion is executed for generalization of experimental results on the basis of results obtained.

  12. Supersonic laser-induced jetting of aluminum micro-droplets

    Energy Technology Data Exchange (ETDEWEB)

    Zenou, M. [Racah Institute of Physics and the Harvey M. Kruger Family Center for Nano-science and Nanotechnology, The Hebrew University of Jerusalem, 91904 Jerusalem (Israel); Additive Manufacturing Lab, Orbotech Ltd., P.O. Box 215, 81101 Yavne (Israel); Sa' ar, A. [Racah Institute of Physics and the Harvey M. Kruger Family Center for Nano-science and Nanotechnology, The Hebrew University of Jerusalem, 91904 Jerusalem (Israel); Kotler, Z. [Additive Manufacturing Lab, Orbotech Ltd., P.O. Box 215, 81101 Yavne (Israel)

    2015-05-04

    The droplet velocity and the incubation time of pure aluminum micro-droplets, printed using the method of sub-nanosecond laser induced forward transfer, have been measured indicating the formation of supersonic laser-induced jetting. The incubation time and the droplet velocity were extracted by measuring a transient electrical signal associated with droplet landing on the surface of the acceptor substrate. This technique has been exploited for studying small volume droplets, in the range of 10–100 femto-litters for which supersonic velocities were measured. The results suggest elastic propagation of the droplets across the donor-to-acceptor gap, a nonlinear deposition dynamics on the surface of the acceptor and overall efficient energy transfer from the laser beam to the droplets.

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

    CERN Document Server

    Thun, Daniel; Schmidt, Franziska; Kley, Wilhelm

    2016-01-01

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

  14. The effects of profiles on supersonic jet noise

    Science.gov (United States)

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

    1994-01-01

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

  15. A new method for laminar boundary layer transition visualization in flight: Color changes in liquid crystal coatings

    Science.gov (United States)

    Holmes, B. J.; Gall, P. D.; Croom, C. C.; Manuel, G. S.; Kelliher, W. C.

    1986-01-01

    The visualization of laminar to turbulent boundary layer transition plays an important role in flight and wind-tunnel aerodynamic testing of aircraft wing and body surfaces. Visualization can help provide a more complete understanding of both transition location as well as transition modes; without visualization, the transition process can be very difficult to understand. In the past, the most valuable transition visualization methods for flight applications included sublimating chemicals and oil flows. Each method has advantages and limitations. In particular, sublimating chemicals are impractical to use in subsonic applications much above 20,000 feet because of the greatly reduced rates of sublimation at lower temperatures (less than -4 degrees Farenheit). Both oil flow and sublimating chemicals have the disadvantage of providing only one good data point per flight. Thus, for many important flight conditions, transition visualization has not been readily available. This paper discusses a new method for visualizing transition in flight by the use of liquid crystals. The new method overcomes the limitations of past techniques, and provides transition visualization capability throughout almost the entire altitude and speed ranges of virtually all subsonic aircraft flight envelopes. The method also has wide applicability for supersonic transition visualization in flight and for general use in wind tunnel research over wide subsonic and supersonic speed ranges.

  16. Handbook of Supersonic Aerodynamics. Section 18. Shock Tubes

    Science.gov (United States)

    1959-12-01

    Supersonic Aerodynamics. The continued encouragement received from Dr. G. N. Patterson is sincerely acknowledged. Thanks are due to E. 0. Gadamer , K...the focal point. However, it is assumed that it is smoothed out very quickly (Ref. 1). This type of wave is difficult to generate in practice , as it...since in practice they quickly turn into a shock front. 2a1The piston velocity u 1--1 - (N - 1), and following the method of Eq. (6), the piston

  17. Supersonic Vortex Gerdien Arc with Magnetic Thermal Insulation

    Science.gov (United States)

    Winterberg, F.

    1988-02-01

    Temperatures up to ~ 5 x 104 oK have been obtained with water vortex Gerdien arcs, and temperatures of ~ 105oK have been reached in hydrogen plasma arcs with magnetic thermal insulation through an externally applied strong magnetic field. It is suggested that a further increase in arc temperatures up to 106oK can conceivably be attained by a combination of both techniques, using a Gerdien arc with a supersonic hydrogen gas vortex.

  18. Wave-driven Rotation in Supersonically Rotating Mirrors

    Energy Technology Data Exchange (ETDEWEB)

    A. Fetterman and N.J. Fisch

    2010-02-15

    Supersonic rotation in mirrors may be produced by radio frequency waves. The waves produce coupled diffusion in ion kinetic and potential energy. A population inversion along the diffusion path then produces rotation. Waves may be designed to exploit a natural kinetic energy source or may provide the rotation energy on their own. Centrifugal traps for fusion and isotope separation may benefit from this wave-driven rotation.

  19. Dynamical separation of spherical bodies in supersonic flow

    OpenAIRE

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

    2012-01-01

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

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

    OpenAIRE

    Vázquez, Mariano; Dervieux, Alain; Koobus, Bruno

    2003-01-01

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

  1. Study on the Characteristics of Supersonic Coanda Jet

    Institute of Scientific and Technical Information of China (English)

    ShigeruMatsuo; ShenYu; 等

    1998-01-01

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

  2. Research on the mechanics of underwater supersonic gas jets

    Science.gov (United States)

    Shi, Honghui; Wang, Boyi; Dai, Zhenqing

    2010-03-01

    An experimental research was carried out to study the fluid mechanics of underwater supersonic gas jets. High pressure air was injected into a water tank through converging-diverging nozzles (Laval nozzles). The jets were operated at different conditions of over-, full- and under-expansions. The jet sequences were visualized using a CCD camera. It was found that the injection of supersonic air jets into water is always accompanied by strong flow oscillation, which is related to the phenomenon of shock waves feedback in the gas phase. The shock wave feedback is different from the acoustic feedback when a supersonic gas jet discharges into open air, which causes screech tone. It is a process that the shock waves enclosed in the gas pocket induce a periodic pressure with large amplitude variation in the gas jet. Consequently, the periodic pressure causes the jet oscillation including the large amplitude expansion. Detailed pressure measurements were also conducted to verify the shock wave feedback phenomenon. Three kinds of measuring methods were used, i.e., pressure probe submerged in water, pressure measurements from the side and front walls of the nozzle devices respectively. The results measured by these methods are in a good agreement. They show that every oscillation of the jets causes a sudden increase of pressure and the average frequency of the shock wave feedback is about 5-10 Hz.

  3. Technical and environmental challenges for the next generation supersonic transport

    Energy Technology Data Exchange (ETDEWEB)

    Pacull, M. [Aerospatiale (France); Hume, Ch. [British Aerospace (United Kingdom)

    1994-12-31

    The next century will be marked by the entry into service of new supersonic transport. The real question concerning the next generation supersonic transport is not will it happen, but when, and how. There is a general agreement that such an airplane will result from a worldwide venture. Who will participate, to what extend and how we will put the vehicle and partners together, are an interesting concern that will need some time to resolve. The other challenges will be to design, build and market an aircraft that will be a viable product: for the passenger, who wants the service of a fast airliner with a reasonable surcharge; for the airline which wants competitive operating cost so that it will make sense to introduce such an airplane in its fleet; for the manufacturer, which not only does not want to go bankruptcy, but seeks to make a profit in the long term within the environmental constraints: no adverse impact on high atmosphere ozone; compliance with noise requirements, operations compatible with sonic boom. This paper does not try to answer all these question, but rather highlight major technical and environmental issues for the next generation supersonic transport. The topics discussed are: general specification, noise, atmospheric emissions, sonic boom, aerodynamics, structures, engine integration, systems. (authors)

  4. Hydrogen tube vehicle for supersonic transport: 2. Speed and energy

    Energy Technology Data Exchange (ETDEWEB)

    Miller, Arnold R. [Vehicle Projects Inc and Supersonic Tubevehicle LLC, 200 Violet St, Suite 100, Golden, CO 80401 (United States)

    2010-06-15

    The central concept of a new idea in high-speed transport is that operation of a vehicle in a hydrogen atmosphere, because of the low density of hydrogen, would increase sonic speed by a factor of 3.8 and decrease drag by 15 relative to air. A hydrogen atmosphere requires that the vehicle operate within a hydrogen-filled tube or pipeline, which serves as a phase separator. The supersonic tube vehicle (STV) can be supersonic with respect to air outside the tube while remaining subsonic inside. It breathes hydrogen fuel for its propulsion fuel cells from the tube itself. This paper, second in a series on the scientific foundations of the supersonic tube vehicle, tests the hypothesis that the STV will be simultaneously fast and energy efficient by comparing its predicted speed and energy consumption with that of four long-haul passenger transport modes: road, rail, maglev, and air. The study establishes the speed ranking STV >> airplane > maglev > train > coach (intercity bus) and the normalized energy consumption ranking Airplane >> coach > maglev > train > STV. Consistent with the hypothesis, the concept vehicle is both the fastest and lowest energy consuming mode. In theory, the vehicle can cruise at Mach 2.8 while consuming less than half the energy per passenger of a Boeing 747 at a cruise speed of Mach 0.81. (author)

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

    Science.gov (United States)

    He, G.; Zhao, Y. X.; Zhou, J.

    2017-03-01

    The interaction of a swept shock wave and a supersonic wake has been studied. The swept shock wave is generated by a swept compression sidewall, and the supersonic wake is generated by a wake generator. The flow field is visualized with the nanoparticle-based planar laser scattering method, and a supplementary numerical simulation is conducted by solving the Reynolds-averaged Navier-Stokes equations. The results show that the pressure rise induced by the swept shock wave can propagate upstream in the wake, which makes the location where vortices are generated move upstream, thickens the laminar section of the wake, and enlarges the generated vortices. The wake is swept away from the swept compression sidewall by the pressure gradient of the swept shock wave. This pressure gradient is not aligned with the density gradient of the supersonic wake, so the baroclinic torque generates streamwise vorticity and changes the distribution of the spanwise vorticity. The wake shock is curved, so the flow downstream of it is non-uniform, leaving the swept shock wave being distorted. A three-dimensional Mach disk structure is generated when the wake shock interacts with the swept shock wave.

  6. Research on the mechanics of underwater supersonic gas jets

    Institute of Scientific and Technical Information of China (English)

    2010-01-01

    An experimental research was carried out to study the fluid mechanics of underwater supersonic gas jets. High pressure air was injected into a water tank through converging-diverging nozzles (Laval nozzles). The jets were operated at different conditions of over-, full- and under-expansions. The jet sequences were visualized using a CCD camera. It was found that the injection of supersonic air jets into water is always accompanied by strong flow oscillation, which is related to the phenomenon of shock waves feedback in the gas phase. The shock wave feedback is different from the acoustic feedback when a supersonic gas jet discharges into open air, which causes screech tone. It is a process that the shock waves enclosed in the gas pocket induce a periodic pressure with large amplitude variation in the gas jet. Consequently, the periodic pressure causes the jet oscillation including the large amplitude expansion. Detailed pressure measurements were also conducted to verify the shock wave feedback phenomenon. Three kinds of measuring methods were used, i.e., pressure probe submerged in water, pressure measurements from the side and front walls of the nozzle devices respectively. The results measured by these methods are in a good agreement. They show that every oscillation of the jets causes a sudden increase of pressure and the average frequency of the shock wave feedback is about 5–10 Hz.

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

    Science.gov (United States)

    He, G.; Zhao, Y. X.; Zhou, J.

    2017-09-01

    The interaction of a swept shock wave and a supersonic wake has been studied. The swept shock wave is generated by a swept compression sidewall, and the supersonic wake is generated by a wake generator. The flow field is visualized with the nanoparticle-based planar laser scattering method, and a supplementary numerical simulation is conducted by solving the Reynolds-averaged Navier-Stokes equations. The results show that the pressure rise induced by the swept shock wave can propagate upstream in the wake, which makes the location where vortices are generated move upstream, thickens the laminar section of the wake, and enlarges the generated vortices. The wake is swept away from the swept compression sidewall by the pressure gradient of the swept shock wave. This pressure gradient is not aligned with the density gradient of the supersonic wake, so the baroclinic torque generates streamwise vorticity and changes the distribution of the spanwise vorticity. The wake shock is curved, so the flow downstream of it is non-uniform, leaving the swept shock wave being distorted. A three-dimensional Mach disk structure is generated when the wake shock interacts with the swept shock wave.

  8. Manufacturing of A micro probe using supersonic aided electrolysis process

    CERN Document Server

    Shyu, R F; Ho, Chi-Ting

    2008-01-01

    In this paper, a practical micromachining technology was applied for the fabrication of a micro probe using a complex nontraditional machining process. A series process was combined to machine tungsten carbide rods from original dimension. The original dimension of tungsten carbide rods was 3mm ; the rods were ground to a fixed-dimension of 50 micrometers using precision grinding machine in first step. And then, the rod could be machined to a middle-dimension of 20 micrometers by electrolysis. A final desired micro dimension can be achieved using supersonic aided electrolysis. High-aspect-ratio of micro tungsten carbide rod was easily obtained by this process. Surface roughness of the sample with supersonic aided agitation was compared with that with no agitation in electrolysis. The machined surface of the sample is very smooth due to ionized particles of anode could be removed by supersonic aided agitation during electrolysis. Deep micro holes can also be achieved by the machined high-aspect-rati tungsten c...

  9. THE TURBULENT DYNAMO IN HIGHLY COMPRESSIBLE SUPERSONIC PLASMAS

    Energy Technology Data Exchange (ETDEWEB)

    Federrath, Christoph [Research School of Astronomy and Astrophysics, The Australian National University, Canberra, ACT 2611 (Australia); Schober, Jennifer [Universität Heidelberg, Zentrum für Astronomie, Institut für Theoretische Astrophysik, Albert-Ueberle-Strasse 2, D-69120 Heidelberg (Germany); Bovino, Stefano; Schleicher, Dominik R. G., E-mail: christoph.federrath@anu.edu.au [Institut für Astrophysik, Georg-August-Universität Göttingen, Friedrich-Hund-Platz 1, D-37077 Göttingen (Germany)

    2014-12-20

    The turbulent dynamo may explain the origin of cosmic magnetism. While the exponential amplification of magnetic fields has been studied for incompressible gases, little is known about dynamo action in highly compressible, supersonic plasmas, such as the interstellar medium of galaxies and the early universe. Here we perform the first quantitative comparison of theoretical models of the dynamo growth rate and saturation level with three-dimensional magnetohydrodynamical simulations of supersonic turbulence with grid resolutions of up to 1024{sup 3} cells. We obtain numerical convergence and find that dynamo action occurs for both low and high magnetic Prandtl numbers Pm = ν/η = 0.1-10 (the ratio of viscous to magnetic dissipation), which had so far only been seen for Pm ≥ 1 in supersonic turbulence. We measure the critical magnetic Reynolds number, Rm{sub crit}=129{sub −31}{sup +43}, showing that the compressible dynamo is almost as efficient as in incompressible gas. Considering the physical conditions of the present and early universe, we conclude that magnetic fields need to be taken into account during structure formation from the early to the present cosmic ages, because they suppress gas fragmentation and drive powerful jets and outflows, both greatly affecting the initial mass function of stars.

  10. Mixed exhaust flow supersonic jet engine and method

    Energy Technology Data Exchange (ETDEWEB)

    Klees, G.W.

    1993-06-08

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

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

    Science.gov (United States)

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

    2016-10-01

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

  12. Study of the flow characteristics of supersonic coaxial jets

    Energy Technology Data Exchange (ETDEWEB)

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

    2001-12-01

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

  13. Flow and acoustic features of a supersonic tapered nozzle

    Science.gov (United States)

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

    1992-05-01

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

  14. MULTILATERAL DIPLOMACY AND INTERNATIONAL REGIMES

    Directory of Open Access Journals (Sweden)

    BENEA Ciprian-Beniamin

    2014-12-01

    Full Text Available The history of diplomacy can by divided in three main periods: one is that of occasional diplomacy peculiar to Middle Ages, while other belong to permane diplomacy, peculiar to modern times. But this one can be divided in two parts, too: one with a bilateral character, previos to 1st World War, and one with a multilateral character, manifested especially after the end on 1st World War. This third type is the focus of present paper. And it cannot be separated from the newly international constructs: international regimes, and international organizations. International instritutions the area where international regimes are belonging to – are legal constructs which provide the formal (and legal framework for continous negotiations. They are the most visible part of the new diplomacy – the one which has a permanent character, and it has an more open face. Anyway, the most important connection has to do with the international institutions, international regimes, and multilateral international negotiations. In the era of the new diplomacy, they all have a permanent character. International institutions help international negotiations carring on; while in their turn, they provide the base for international regimes’ creation, and especially for their evolution. The international regimes’ evolution is an inseparable part of a permanent international framework. And if there is missing a permanent international framework (international organization connected to a specific regime, this regime is a difuse one, its members have only informal relations among them, while they survey each other, looking at their behavior, but they don’t have a formal relationship among them, which could help them solving their future common interests, and protect them from their common fears. International regimes are very important in the era when evrithing touches, and influences everything. In the same time, the complexity of our present world can be successfully

  15. Mach number study of supersonic turbulence: The properties of the density field

    CERN Document Server

    Konstandin, Lukas; Girichidis, Philipp; Peters, Thomas; Shetty, Rahul; Klessen, Ralf S

    2015-01-01

    We model driven, compressible, isothermal, turbulence with Mach numbers ranging from the subsonic ($\\mathcal{M} \\approx 0.65$) to the highly supersonic regime ($\\mathcal{M}\\approx 16 $). The forcing scheme consists both solenoidal (transverse) and compressive (longitudinal) modes in equal parts. We find a relation $\\sigma_{s}^2 = \\mathrm{b}\\log{(1+\\mathrm{b}^2\\mathcal{M}^2)}$ between the Mach number and the standard deviation of the logarithmic density with $\\mathrm{b} = 0.457 \\pm 0.007$. The density spectra follow $\\mathcal{D}(k,\\,\\mathcal{M}) \\propto k^{\\zeta(\\mathcal{M})}$ with scaling exponents depending on the Mach number. We find $\\zeta(\\mathcal{M}) = \\alpha \\mathcal{M}^{\\beta}$ with a coefficient $\\alpha$ that varies slightly with resolution, whereas $\\beta$ changes systematically. We extrapolate to the limit of infinite resolution and find $\\alpha = -1.91 \\pm 0.01,\\, \\beta =-0.30\\pm 0.03$. The dependence of the scaling exponent on the Mach number implies a fractal dimension $D=2+0.96 \\mathcal{M}^{-0.3...

  16. Electrochemical impedance spectroscopy on nanostructured carbon electrodes grown by supersonic cluster beam deposition

    Energy Technology Data Exchange (ETDEWEB)

    Bettini, Luca Giacomo; Bardizza, Giorgio; Podesta, Alessandro; Milani, Paolo; Piseri, Paolo, E-mail: piseri@mi.infn.it [Universita degli Studi di Milano, Dipartimento di Fisica and CIMaINa (Italy)

    2013-02-15

    Nanostructured porous films of carbon with density of about 0.5 g/cm{sup 3} and 200 nm thickness were deposited at room temperature by supersonic cluster beam deposition (SCBD) from carbon clusters formed in the gas phase. Carbon film surface topography, determined by atomic force microscopy, reveals a surface roughness of 16 nm and a granular morphology arising from the low kinetic energy ballistic deposition regime. The material is characterized by a highly disordered carbon structure with predominant sp2 hybridization as evidenced by Raman spectroscopy. The interface properties of nanostructured carbon electrodes were investigated by cyclic voltammetry and electrochemical impedance spectroscopy employing KOH 1 M solution as aqueous electrolyte. An increase of the double layer capacitance is observed when the electrodes are heat treated in air or when a nanostructured nickel layer deposited by SCBD on top of a sputter deposited film of the same metal is employed as a current collector instead of a plain metallic film. This enhancement is consistent with an improved charge injection in the active material and is ascribed to the modification of the electrical contact at the interface between the carbon and the metal current collector. Specific capacitance values up to 120 F/g have been measured for the electrodes with nanostructured metal/carbon interface.

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

    Science.gov (United States)

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

    2008-11-01

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

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

    Science.gov (United States)

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

    2016-05-01

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

  19. Bifurcation Tools for Flight Dynamics Analysis and Control System Design Project

    Data.gov (United States)

    National Aeronautics and Space Administration — Modern bifurcation analysis methods have been proposed for investigating flight dynamics and control system design in highly nonlinear regimes and also for the...

  20. Great Lakes' regional climate regimes

    Science.gov (United States)

    Kravtsov, Sergey; Sugiyama, Noriyuki; Roebber, Paul

    2016-04-01

    We simulate the seasonal cycle of the Great Lakes' water temperature and lake ice using an idealized coupled lake-atmosphere-ice model. Under identical seasonally varying boundary conditions, this model exhibits more than one seasonally varying equilibrium solutions, which we associate with distinct regional climate regimes. Colder/warmer regimes are characterized by abundant/scarce amounts of wintertime ice and cooler/warmer summer temperatures, respectively. These regimes are also evident in the observations of the Great Lakes' climate variability over recent few decades, and are found to be most pronounced for Lake Superior, the deepest of the Great Lakes, consistent with model predictions. Multiple climate regimes of the Great Lakes also play a crucial role in the accelerated warming of the lakes relative to the surrounding land regions in response to larger-scale global warming. We discuss the physical origin and characteristics of multiple climate regimes over the lakes, as well as their implications for a longer-term regional climate variability.

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

    Science.gov (United States)

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

    1952-01-01

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

  2. Conceptual design of high speed supersonic aircraft: A brief review on SR-71 (Blackbird) aircraft

    Science.gov (United States)

    Xue, Hui; Khawaja, H.; Moatamedi, M.

    2014-12-01

    The paper presents the conceptual design of high-speed supersonic aircraft. The study focuses on SR-71 (Blackbird) aircraft. The input to the conceptual design is a mission profile. Mission profile is a flight profile of the aircraft defined by the customer. This paper gives the SR-71 aircraft mission profile specified by US air force. Mission profile helps in defining the attributes the aircraft such as wing profile, vertical tail configuration, propulsion system, etc. Wing profile and vertical tail configurations have direct impact on lift, drag, stability, performance and maneuverability of the aircraft. A propulsion system directly influences the performance of the aircraft. By combining the wing profile and the propulsion system, two important parameters, known as wing loading and thrust to weight ratio can be calculated. In this work, conceptual design procedure given by D. P. Raymer (AIAA Educational Series) is applied to calculate wing loading and thrust to weight ratio. The calculated values are compared against the actual values of the SR-71 aircraft. Results indicates that the values are in agreement with the trend of developments in aviation.

  3. An experimental system for release simulation of internal stores in a supersonic wind tunnel

    Directory of Open Access Journals (Sweden)

    Wei Liu

    2017-02-01

    Full Text Available Aerodynamic parameters obtained from separation experiments of internal stores in a wind tunnel are significant in aircraft designs. Accurate wind tunnel tests can help to improve the release stability of the stores and in-flight safety of the aircrafts in supersonic environments. A simulative system for free drop experiments of internal stores based on a practical project is provided in this paper. The system contains a store release mechanism, a control system and an attitude measurement system. The release mechanism adopts a six-bar linkage driven by a cylinder, which ensures the release stability. The structure and initial aerodynamic parameters of the stores are also designed and adjusted. A high speed vision measurement system for high speed rolling targets is utilized to measure the pose parameters of the internal store models and an optimizing method for the coordinates of markers is presented based on a priori model. The experimental results show excellent repeatability of the system, and indicate that the position measurement precision is less than 0.13 mm, and the attitude measurement precision for pitch and yaw angles is less than 0.126°, satisfying the requirements of practical wind tunnel tests. A separation experiment for the internal stores is also conducted in the FL-3 wind tunnel of China Aerodynamics Research Institute.

  4. The gas density measurement of one long distance supersonic molecular beam

    Science.gov (United States)

    Liu, D.; Han, J. F.; Chen, Z. Y.; Bai, L. X.; Zhou, J. X.

    2016-12-01

    The gas density of the supersonic molecular beam (SMB) is a crucial parameter for the fueling or diagnostic process in the tokamak experiments. Using the microphone, one improved method of gas density measurement is proposed, which can greatly improve the measurement capacity by about 3 orders of magnitude by studying the pulsed signal characteristic of the microphone when it is pushed by the SMB. The gas density of the SMB is measured within the axial range of 20-2000 mm, and the axial central density at 2000 mm is about 100 times less than that at 20 mm. It is also found that the radial density distribution follows the Gaussian function in both free expansion (where the SMB can expand freely without any influence from the vacuum chamber) and restricted expansion (where the expansion of the SMB is restricted inside the flight tube of the vacuum system). And the axial central density decreases with the axial distance, which follows the inverse square law in the free expansion, but it deviates from this law in the restricted expansion.

  5. An Experimental Investigation of the Aeroacoustics of a Two-Dimensional Bifurcated Supersonic Inlet

    Science.gov (United States)

    LI, S.-M.; HANUSKA, C. A.; NG, W. F.

    2001-11-01

    An experiment was conducted on a two-dimensional bifurcated, supersonic inlet to investigate the aeroacoustics at take-off and landing conditions. A 104·1 mm (4·1 in) diameter turbofan simulator was coupled to the inlet to generate the noise typical of a turbofan engine. Aerodynamic and acoustic data were obtained in an anechoic chamber under ground-static conditions (i.e., no forward flight effect). Results showed that varying the distance between the trailing edge of the bifurcated ramp of the inlet and the fan face had negligible effect on the total noise level. Thus, one can have a large freedom to design the bifurcated ramp mechanically and aerodynamically, with minimum impact on the aeroacoustics. However, the effect of inlet guide vanes' (IGV) axial spacing to the fan face has a first order effect on the aeroacoustics for the bifurcated 2-D inlet. As much as 5 dB reduction in the overall sound pressure level and as much as 15 dB reduction in the blade passing frequency tone were observed when the IGV was moved from 0·8 chord of rotor blade upstream of the fan face to 2·0 chord of the blade upstream. The wake profile similarity of the IGV was also found in the flow environment of the 2-D bifurcated inlet, i.e., the IGV wakes followed the usual Gauss' function.

  6. Friction Regimes in the Lubricants Solid-State Regime

    NARCIS (Netherlands)

    Schipper, D.J.; Maathuis, O.; Dowson, D.; Taylor, C.M.; Childs, T.H.C.; Dalmaz, G.

    1995-01-01

    Friction measurements were performed in the lubricant's solid-state regime to study the transition from full-film lubrication, in which the separation is maintained by a solidified lubricant, to mixed lubrication. Special attention is paid to the influence of temperature (inlet viscosity) and roughn

  7. Manned Flight Simulator (MFS)

    Data.gov (United States)

    Federal Laboratory Consortium — The Aircraft Simulation Division, home to the Manned Flight Simulator (MFS), provides real-time, high fidelity, hardware-in-the-loop flight simulation capabilities...

  8. 14 CFR 91.109 - Flight instruction; Simulated instrument flight and certain flight tests.

    Science.gov (United States)

    2010-01-01

    ... 14 Aeronautics and Space 2 2010-01-01 2010-01-01 false Flight instruction; Simulated instrument flight and certain flight tests. 91.109 Section 91.109 Aeronautics and Space FEDERAL AVIATION... OPERATING AND FLIGHT RULES Flight Rules General § 91.109 Flight instruction; Simulated instrument flight...

  9. On the Comparison of the Long Penetration Mode (LPM) Supersonic Counterflowing Jet to the Supersonic Screech Jet

    Science.gov (United States)

    Farr, Rebecca A.; Chang, Chau-Lyan.; Jones, Jess H.; Dougherty, N. Sam

    2015-01-01

    The authors provide a brief overview of the classic tonal screech noise problem created by underexpanded supersonic jets, briefly describing the fluid dynamic-acoustics feedback mechanism that has been long established as the basis for this well-known aeroacoustics problem. This is followed by a description of the Long Penetration Mode (LPM) supersonic underexpanded counterflowing jet phenomenon which has been demonstrated in several wind tunnel tests and modeled in several computational fluid dynamics (CFD) simulations. The authors provide evidence from test and CFD analysis of LPM that indicates that acoustics feedback and fluid interaction seen in LPM are analogous to the aeroacoustics interactions seen in screech jets. Finally, the authors propose applying certain methodologies to LPM which have been developed and successfully demonstrated in the study of screech jets and mechanically induced excitation in fluid oscillators for decades. The authors conclude that the large body of work done on jet screech, other aeroacoustic phenomena, and fluid oscillators can have direct application to the study and applications of LPM counterflowing supersonic cold flow jets.

  10. On the regimes of premixing

    Energy Technology Data Exchange (ETDEWEB)

    Angelini, S.; Theofanous, T.G.; Yuen, W.W. [California Univ., Santa Barbara, CA (United States). Center for Risk Studies and Safety

    1998-01-01

    The conditions of the MAGICO-2000 experiment are extended to more broadly investigate the regimes of premixing, and the corresponding internal structures of mixing zones. With the help of the data and numerical simulations using the computer code PM-ALPHA, we can distinguish extremes of behavior dominated by inertia and thermal effects - we name these the inertia and thermal regimes, respectively. This is an important distinction that should guide future experiments aimed at code verification in this area. Interesting intermediate behaviors are also delineated and discussed. (author)

  11. Surface tension dominates insect flight on fluid interfaces.

    Science.gov (United States)

    Mukundarajan, Haripriya; Bardon, Thibaut C; Kim, Dong Hyun; Prakash, Manu

    2016-03-01

    Flight on the 2D air-water interface, with body weight supported by surface tension, is a unique locomotion strategy well adapted for the environmental niche on the surface of water. Although previously described in aquatic insects like stoneflies, the biomechanics of interfacial flight has never been analysed. Here, we report interfacial flight as an adapted behaviour in waterlily beetles (Galerucella nymphaeae) which are also dexterous airborne fliers. We present the first quantitative biomechanical model of interfacial flight in insects, uncovering an intricate interplay of capillary, aerodynamic and neuromuscular forces. We show that waterlily beetles use their tarsal claws to attach themselves to the interface, via a fluid contact line pinned at the claw. We investigate the kinematics of interfacial flight trajectories using high-speed imaging and construct a mathematical model describing the flight dynamics. Our results show that non-linear surface tension forces make interfacial flight energetically expensive compared with airborne flight at the relatively high speeds characteristic of waterlily beetles, and cause chaotic dynamics to arise naturally in these regimes. We identify the crucial roles of capillary-gravity wave drag and oscillatory surface tension forces which dominate interfacial flight, showing that the air-water interface presents a radically modified force landscape for flapping wing flight compared with air.

  12. Ornithopter flight stabilization

    Science.gov (United States)

    Dietl, John M.; Garcia, Ephrahim

    2007-04-01

    The quasi-steady aerodynamics model and the vehicle dynamics model of ornithopter flight are explained, and numerical methods are described to capture limit cycle behavior in ornithopter flight. The Floquet method is used to determine stability in forward flight, and a linear discrete-time state-space model is developed. This is used to calculate stabilizing and disturbance-rejecting controllers.

  13. White flight or flight from poverty?

    CERN Document Server

    Jego, C; Jego, Charles; Roehner, Bertrand M.

    2006-01-01

    The phenomenon of White flight is often illustrated by the case of Detroit whose population dropped from 1.80 million to 0.95 million between 1950 and 2000 while at the same time its Black and Hispanic component grew from 30 percent to 85 percent. But is this case really representative? The present paper shows that the phenomenon of White flight is in fact essentially a flight from poverty. As a confirmation, we show that the changes in White or Black populations are highly correlated which means that White flight is always paralleled by Black flight (and Hispanic flight as well). This broader interpretation of White flight accounts not only for the case of northern cities such as Cincinnati, Cleveland or Detroit, but for all population changes at county level, provided the population density is higher than a threshold of about 50 per square-kilometer which corresponds to moderately urbanized areas (as can be found in states like Indiana or Virginia for instance).

  14. Monetary regimes in open economies

    NARCIS (Netherlands)

    Korpos, A.

    2006-01-01

    This thesis presents a two-country open economy framework for the analysis of strategic interactions among monetary authorities and wage bargaining institutions. From this perspective, the thesis investigates the economic consequences of replacing flexible and fixed exchange rate regimes with a mone

  15. Microgravity Flow Regime Data: Buoyancy and Mixing Apparatus Effects

    Science.gov (United States)

    Shephard, Adam; Best, Frederick

    2010-01-01

    Zero-g two-phase flow data set qualification and flight experiment design have not been standardized and as a result, agreement among researchers has not been reached regarding what experimental conditions adequately approximate those of microgravity. The effects of buoyancy forces and mixing apparatus on the flow regime transitions are presented in this study. The gravity conditions onboard zero-g aircraft are at best 10-3 g which is used to approximate the 10-5 g conditions of microgravity, thus the buoyancy forces present on zero-g aircraft can become significantly large and unrepresentative of microgravity. When buoyancy forces approach those of surface tension forces, buoyancy induced coalescence occurs. When discussing flow regime transitions, these large buoyancy forces lead to flow regime transitions which otherwise would not occur. The buoyancy attributes of the two-phase flow data sets available in the literature are evaluated to determine which data sets exhibit buoyancy induced transitions. Upon comparison of the representative data sets, the affects of different mixing apparatus can be seen in the superficial velocity flow regime maps.

  16. Supersonic transient magnetic resonance elastography for quantitative assessment of tissue elasticity

    Science.gov (United States)

    Liu, Yu; Liu, Jingfei; Fite, Brett Z.; Foiret, Josquin; Ilovitsh, Asaf; Leach, J. Kent; Dumont, Erik; Caskey, Charles F.; Ferrara, Katherine W.

    2017-05-01

    Non-invasive, quantitative methods to assess the properties of biological tissues are needed for many therapeutic and tissue engineering applications. Magnetic resonance elastography (MRE) has historically relied on external vibration to generate periodic shear waves. In order to focally assess a biomaterial or to monitor the response to ablative therapy, the interrogation of a specific region of interest by a focused beam is desirable and transient MRE (t-MRE) techniques have previously been developed to accomplish this goal. Also, strategies employing a series of discrete ultrasound pulses directed to increasing depths along a single line-of-sight have been designed to generate a quasi-planar shear wave. Such ‘supersonic’ excitations have been applied for ultrasound elasticity measurements. The resulting shear wave is higher in amplitude than that generated from a single excitation and the properties of the media are simply visualized and quantified due to the quasi-planar wave geometry and the opportunity to generate the wave at the site of interest. Here for the first time, we extend the application of supersonic methods by developing a protocol for supersonic transient magnetic resonance elastography (sst-MRE) using an MR-guided focused ultrasound system capable of therapeutic ablation. We apply the new protocol to quantify tissue elasticity in vitro using biologically-relevant inclusions and tissue-mimicking phantoms, compare the results with elasticity maps acquired with ultrasound shear wave elasticity imaging (US-SWEI), and validate both methods with mechanical testing. We found that a modified time-of-flight (TOF) method efficiently quantified shear modulus from sst-MRE data, and both the TOF and local inversion methods result in similar maps based on US-SWEI. With a three-pulse excitation, the proposed sst-MRE protocol was capable of visualizing quasi-planar shear waves propagating away from the excitation location and detecting differences in shear

  17. X-1A in flight with flight data superimposed

    Science.gov (United States)

    1953-01-01

    crew returned to base in satisfactory condition. Four pilots had completed 29 flights (including aborts). X-1B The Bell Aircraft Corporation X-1B was similar to the Bell X-1A except for the installation of wingtips extensions for its last three flight. The NACA portion of the X-1B flight test program was for the purpose of aerodynamic heating research, accumulating data during 1956-1958. The X-1B was fitted with special instrumentation for exploratory aerodynamic heating tests. It had over 300 thermocouples installed on it. It was the first aircraft to fly with a reaction control system, a prototype of the control system used on the X-15 and other piloted aircraft. Midway through its flight test program, the X-1B was equipped with an Reaction Motors, Inc. XLR-11-RM-9 engine which differed, from the other XLR-11s, only in having an electric spark, low-tension interrupter type ignition in place of the older high-tension type. On January 27, 1959 the X-1B was given to the Air Force Museum at Wright-Patterson Air Force Base, Ohio, for preservation and public display. This aircraft completed a total of 27 glide and powered flights made by eight USAF test pilots and two NACA test pilots. X-1C Following the X-1B was the projected X-1C, which was canceled while still in the mock-up stage. The birth of transonic and supersonic-capable aircraft like the North American F-86 Sabre and the North American F-100 Super Sabre eventually eliminated the need for the X-1C. X-1D The X-1D was the first advanced model of the X-1 family to roll from Bell Aircraft Corporation's plant. It arrived at Edwards, California, in July 1951 suspended from the bomb bay shackles of a Boeing EB-50A, (46-006) aircraft. On July 24, 1951, with Bell test pilot Jean 'Skip' Ziegler at the controls, the X-1D had the only successful flight of its career. It was an unpowered glide flight, and on landing the nose gear failed with the plane sliding to a stop. The aircraft was repaired and ready once more for flight

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

    Institute of Scientific and Technical Information of China (English)

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

    2016-01-01

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

  19. Bibliography of Supersonic Cruise Research (SCR) program from 1980 to 1983

    Science.gov (United States)

    Hoffman, S.

    1984-01-01

    A bibliography for the Supersonic Cruise Research (SCR) and Variable Cycle Engine (VCE) Programs is presented. An annotated bibliography for the last 123 formal reports and a listing of titles for 44 articles and presentations is included. The studies identifies technologies for producing efficient supersonic commercial jet transports for cruise Mach numbers from 2.0 to 2.7.

  20. 3 TUNNELS IN THE ENGINE RESEARCH BUILDING ERB - IN CELL CE-26 VARIABLE REYNOLDS NUMBER SUPERSONIC NO

    Science.gov (United States)

    1956-01-01

    3 TUNNELS IN THE ENGINE RESEARCH BUILDING ERB - IN CELL CE-26 VARIABLE REYNOLDS NUMBER SUPERSONIC NOZZLE - CELL CE-4 6X6 INCH MACH NUMBER 2.96 SUPERSONIC AIRPLANE - CELL 1-NW 1X1 FOOT MACH 3.12 SUPERSONIC TUNNEL

  1. A unified flight control methodology for a compound rotorcraft in fundamental and aerobatic maneuvering flight

    Science.gov (United States)

    Thorsen, Adam

    regime. An energy management system was developed in order to manage performance limits (namely power required) to promote carefree maneuvering and alleviate pilot workload. This system features limits on pilot commands and has additional logic for preserving control margins and limiting maximum speed in a dive. Nonlinear dynamic inversion (NLDI) is the framework of the unified controller, which incorporates primary and redundant controls. The inner loop of the NLDI controller regulates bank angle, pitch attitude, and yaw rate, while the outer loop command structure is varied (three modes). One version uses an outer loop that commands velocities in the longitudinal and vertical axes (velocity mode), another commands longitudinal acceleration and vertical speed (acceleration mode), and the third commands longitudinal acceleration and transitions from velocity to acceleration command in the vertical axis (aerobatic mode). The flight envelope is discretized into low, cruise, and high speed flight regimes. The unified outer loop primary control effectors for the longitudinal and vertical axes (collective pitch, pitch attitude, and propeller pitch) vary depending on flight regime. A weighted pseudoinverse is used to phase either the collective or propeller pitch in/out of a redundant control role. The controllers were evaluated in Penn State's Rotorcraft Flight Simulator retaining the cyclic stick for vertical and lateral axis control along with pedal inceptors for yaw axis control. A throttle inceptor was used in place of the pilot's traditional left hand inceptor for longitudinal axis control. Ultimately, a simple rigid body model of the aircraft was sufficient enough to design a controller with favorable performance and stability characteristics. This unified flight control system promoted a low enough pilot workload so that an untrained pilot (the author) was able to pilot maneuvers of varying complexity with ease. The framework of this unified system is generalized

  2. Experimental investigation of the noise reduction of supersonic exhaust jets with fluidic inserts

    Science.gov (United States)

    Powers, Russell William Walter

    The noise produced by the supersonic, high temperature jets that exhaust from military aircraft is becoming a hazard to naval personnel and a disturbance to communities near military bases. Methods to reduce the noise produced from these jets in a practical full-scale environment are difficult. The development and analysis of distributed nozzle blowing for the reduction of radiated noise from supersonic jets is described. Model scale experiments of jets that simulate the exhaust jets from typical low-bypass ratio military jet aircraft engines during takeoff are performed. Fluidic inserts are created that use distributed blowing in the divergent section of the nozzle to simulate mechanical, hardwall corrugations, while having the advantage of being an active control method. This research focuses on model scale experiments to better understand the fluidic insert noise reduction method. Distributed blowing within the divergent section of the military-style convergent divergent nozzle alters the shock structure of the jet in addition to creating streamwise vorticity for the reduction of mixing noise. Enhancements to the fluidic insert design have been performed along with experiments over a large number of injection parameters and core jet conditions. Primarily military-style round nozzles have been used, with preliminary measurements of hardwall corrugations and fluidic inserts in rectangular nozzle geometries also performed. It has been shown that the noise reduction of the fluidic inserts is most heavily dependent upon the momentum flux ratio between the injector and core jet. Maximum reductions of approximately 5.5 dB OASPL have been observed with practical mass flow rates and injection pressures. The first measurements with fluidic inserts in the presence of a forward flight stream have been performed. Optimal noise reduction occurs at similar injector parameters in the presence of forward flight. Fluidic inserts in the presence of a forward flight stream were

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

    Science.gov (United States)

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

    2001-01-01

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

  4. Climate impact of supersonic air traffic: an approach to optimize a potential future supersonic fleet – results from the EU-project SCENIC

    Directory of Open Access Journals (Sweden)

    L. Gulstad

    2007-05-01

    Full Text Available The demand for intercontinental transportation is increasing and people are requesting short travel times, which supersonic air transportation would enable. However, besides noise and sonic boom issues, which we are not referring to in this investigation, emissions from supersonic aircraft are known to alter the atmospheric composition, in particular the ozone layer, and hence affect climate significantly more than subsonic aircraft. Here, we suggest a metric to quantitatively assess different options for supersonic transport with regard to the potential destruction of the ozone layer and climate impacts. Options for fleet size, engine technology (nitrogen oxide emission level, cruising speed, range, and cruising altitude, are analyzed, based on SCENIC emissions scenarios for 2050, which underlay the requirements to be as realistic as possible in terms of e.g. economic markets and profitable market penetration. This methodology is based on a number of atmosphere-chemistry and climate models to reduce model dependencies. The model results differ significantly in terms of the response to a replacement of subsonic aircraft by supersonic aircraft. However, model differences are smaller when comparing the different options for a supersonic fleet. The base scenario, where supersonic aircraft get in service in 2015, a first fleet fully operational in 2025 and a second in 2050, lead in our simulations to a near surface temperature increase in 2050 of around 7 mK and with constant emissions afterwards to around 21 mK in 2100. The related total radiative forcing amounts to 22 mWm²in 2050, with an uncertainty between 9 and 29 mWm². A reduced supersonic cruise altitude or speed (from March 2 to Mach 1.6 reduces both, climate impact and ozone destruction, by around 40%. An increase in the range of the supersonic aircraft leads to more emissions at lower latitudes since more routes to SE Asia are taken into account, which increases ozone depletion, but

  5. Development of air to air ejector for supersonic wind tunnel

    Directory of Open Access Journals (Sweden)

    Kracík Jan

    2014-03-01

    Full Text Available The contribution deals with the development of design of new conception of ejector with twelve primary annular nozzles arranged around the inlet part of the mixing chamber. The ejector is proposed to be used for propulsion of supersonic experimental wind tunnel with variable test section, which is now in development. The ejector is considered to be placed on outlet of this wind tunnel. The original design of the ejector has been modified to ensure its manufacturability. Software Ansys Fluent 14.0 was used for numerical verification of earlier work. The new design and dissimilarities of numerical results are presented in this work.

  6. Direct formulation of the supersonic acoustic intensity in space domain

    DEFF Research Database (Denmark)

    Fernandez Grande, Efren; Jacobsen, Finn; Leclre, Quentin

    2012-01-01

    This paper proposes and examines a direct formulation in space domain of the so-called supersonic acoustic intensity. This quantity differs from the usual (active) intensity by excluding the circulating energy in the near-field of the source, providing a map of the acoustic energy that is radiated...... by means of a two-dimensional convolution between the acoustic field and a spatial filter mask that corresponds to the space domain representation of the radiation circle. Therefore, the acoustic field that propagates effectively to the far field is calculated via direct filtering in space domain...

  7. Accuracy Of Hot-Wire Anemometry In Supersonic Turbulence

    Science.gov (United States)

    Logan, Pamela; Mckenzie, Robert L.; Bershader, Daniel

    1989-01-01

    Sensitivity of hot-wire probe compared to laser-induced-florescence measurements. Report discusses factors affecting readings of hot-wire anemometer in turbulent supersonic boundary layer. Presents theoretical analysis of responses of hot-wire probe to changes in flow; also compares measurements by hot-wire probe with measurements of same flows by laser-induced fluorescence (LIF). Because LIF provides spatially and temporally resolved data on temperature, density, and pressure, provides independent means to determine responses of hot-wire anemometers to these quantities.

  8. Laboratory plasma physics experiments using merging supersonic plasma jets

    OpenAIRE

    Hsu, S C; Moser, A. L.; Merritt, E. C.; Adams, C. S.; Dunn, J. P.; Brockington, S.; Case, A; Gilmore, M.; Lynn, A. G.; Messer, S. J.; Witherspoon, F. D.

    2014-01-01

    We describe a laboratory plasma physics experiment at Los Alamos National Laboratory that uses two merging supersonic plasma jets formed and launched by pulsed-power-driven rail guns. The jets can be formed using any atomic species or mixture available in a compressed-gas bottle and have the following nominal initial parameters at the railgun nozzle exit: $n_e\\approx n_i \\sim 10^{16}$ cm$^{-3}$, $T_e \\approx T_i \\approx 1.4$ eV, $V_{\\rm jet}\\approx 30$-100 km/s, mean charge $\\bar{Z}\\approx 1$...

  9. Pulsed supersonic helium beams for plasma edge diagnosis

    Science.gov (United States)

    Diez-Rojo, T.; Herrero, V. J.; Tanarro, I.; Tabarés, F. L.; Tafalla, D.

    1997-03-01

    An experimental setup for the production of pulsed supersonic He beams to be used for plasma edge diagnosis in fusion devices is described. A compromise between compact design, low cost, and good quality of the probe beams has been met. The main characteristics of the generated beams, such as pulse shape, absolute flux intensity, and velocity distribution, differ in general from those expected for ideal beam performance and have been determined and optimized experimentally. A first test of this He beam source at the TJ-I UP Torsatron in Madrid is also reported.

  10. Pulsed supersonic helium beams for plasma edge diagnosis

    Energy Technology Data Exchange (ETDEWEB)

    Diez-Rojo, T.; Herrero, V.J.; Tanarro, I. [Instituto de Estructura de la Materia (CSIC), Serrano 123, 28006 Madrid (Spain); Tabares, F.L.; Tafalla, D. [Asociacion EURATOM-CIEMAT para Fusion, Avenue Complutense 22, 28040 Madrid (Spain)

    1997-03-01

    An experimental setup for the production of pulsed supersonic He beams to be used for plasma edge diagnosis in fusion devices is described. A compromise between compact design, low cost, and good quality of the probe beams has been met. The main characteristics of the generated beams, such as pulse shape, absolute flux intensity, and velocity distribution, differ in general from those expected for ideal beam performance and have been determined and optimized experimentally. A first test of this He beam source at the TJ-I UP Torsatron in Madrid is also reported. {copyright} {ital 1997 American Institute of Physics.}

  11. Exchange rate regimes and monetary arrangements

    Directory of Open Access Journals (Sweden)

    Ivan Ribnikar

    2005-06-01

    Full Text Available There is a close relationship between a country’s exchange rate regime and monetary arrangement and if we are to examine monetary arrangements then exchange rate regimes must first be analysed. Within the conventional and most widely used classification of exchange rate regimes into rigid and flexible or into polar regimes (hard peg and float on one side, and intermediate regimes on the other there, is a much greater variety among intermediate regimes. A more precise and, as will be seen, more useful classification of exchange rate regimes is the first topic of the paper. The second topic is how exchange rate regimes influence or determine monetary arrangements and monetary policy or monetary policy regimes: monetary autonomy versus monetary nonautonomy and discretion in monetary policy versus commitment in monetary policy. Both topics are important for countries on their path to the EU and the euro area

  12. The Concept of Truth Regime

    Directory of Open Access Journals (Sweden)

    Lorna Weir

    2008-07-01

    Full Text Available “Truth regime” is a much used but little theorized concept, with the Foucauldian literature presupposing that truth in modernity is uniformly scientific/quasi-scientific and enhances power. I argue that the forms of truth characteristic of our present are wider than Foucault recognized, their relations to power more various, and their historicity more complex. The truth regime of advanced modernity is characterized by multiple, irreducible truth formulae that co-exist and sometimes vie for dominance. A truth formula stabilizes a network of elements: a relation between representation and presentation (words and things, truth and non-truth, and the place of the subject in discourse. Our contemporary truth regime comprises radically heterogeneous truthful knowledges – science, governance, religion/politics, and common culture – that have distinct histories and relations to power.

  13. Detecting spatial regimes in ecosystems

    Science.gov (United States)

    Sundstrom, Shana M.; Eason, Tarsha; Nelson, R. John; Angeler, David G.; Barichievy, Chris; Garmestani, Ahjond S.; Graham, Nicholas A.J.; Granholm, Dean; Gunderson, Lance; Knutson, Melinda; Nash, Kirsty L.; Spanbauer, Trisha; Stow, Craig A.; Allen, Craig R.

    2017-01-01

    Research on early warning indicators has generally focused on assessing temporal transitions with limited application of these methods to detecting spatial regimes. Traditional spatial boundary detection procedures that result in ecoregion maps are typically based on ecological potential (i.e. potential vegetation), and often fail to account for ongoing changes due to stressors such as land use change and climate change and their effects on plant and animal communities. We use Fisher information, an information theory-based method, on both terrestrial and aquatic animal data (U.S. Breeding Bird Survey and marine zooplankton) to identify ecological boundaries, and compare our results to traditional early warning indicators, conventional ecoregion maps and multivariate analyses such as nMDS and cluster analysis. We successfully detected spatial regimes and transitions in both terrestrial and aquatic systems using Fisher information. Furthermore, Fisher information provided explicit spatial information about community change that is absent from other multivariate approaches. Our results suggest that defining spatial regimes based on animal communities may better reflect ecological reality than do traditional ecoregion maps, especially in our current era of rapid and unpredictable ecological change.

  14. The very slow expansion of an ultracold plasma formed in a seeded supersonic molecular beam of NO

    CERN Document Server

    Morrison, J P; Grant, E R

    2008-01-01

    The double-resonant laser excitation of nitric oxide, cooled to 1 K in a seeded supersonic molecular beam, yields a gas of $\\approx10^{12}$ molecules cm$^{-3}$ in a single selected Ryberg state. This population evolves to produce prompt free electrons and a durable cold plasma of electrons and intact NO$^{+}$ ions. This plasma travels with the molecular beam through a field free region to encounter a grid. The atomic weight of the expansion gas controls the beam velocity and hence the flight time from the interaction region to the grid. Monitoring electron production as the plasma traverses this grid measures its longitudinal width as a function of flight time. Comparing these widths to the width of the laser beam that defines the initial size of the illuminated volume allows us to gauge the rate of expansion of the plasma. We find that the plasma created from the evolution of a Rydberg gas of NO expands at a small but measurable rate, and that this rate of expansion accords with the Vlasov equations for an i...

  15. Bat flight: aerodynamics, kinematics and flight morphology.

    Science.gov (United States)

    Hedenström, Anders; Johansson, L Christoffer

    2015-03-01

    Bats evolved the ability of powered flight more than 50 million years ago. The modern bat is an efficient flyer and recent research on bat flight has revealed many intriguing facts. By using particle image velocimetry to visualize wake vortices, both the magnitude and time-history of aerodynamic forces can be estimated. At most speeds the downstroke generates both lift and thrust, whereas the function of the upstroke changes with forward flight speed. At hovering and slow speed bats use a leading edge vortex to enhance the lift beyond that allowed by steady aerodynamics and an inverted wing during the upstroke to further aid weight support. The bat wing and its skeleton exhibit many features and control mechanisms that are presumed to improve flight performance. Whereas bats appear aerodynamically less efficient than birds when it comes to cruising flight, they have the edge over birds when it comes to manoeuvring. There is a direct relationship between kinematics and the aerodynamic performance, but there is still a lack of knowledge about how (and if) the bat controls the movements and shape (planform and camber) of the wing. Considering the relatively few bat species whose aerodynamic tracks have been characterized, there is scope for new discoveries and a need to study species representing more extreme positions in the bat morphospace.

  16. The shock-vortex interaction patterns affected by vortex flow regime and vortex models

    Science.gov (United States)

    Chang, Keun-Shik; Barik, Hrushikesh; Chang, Se-Myong

    2009-08-01

    We have used a third-order essentially non-oscillatory method to obtain numerical shadowgraphs for investigation of shock-vortex interaction patterns. To search different interaction patterns, we have tested two vortex models (the composite vortex model and the Taylor vortex model) and as many as 47 parametric data sets. By shock-vortex interaction, the impinging shock is deformed to a S-shape with leading and lagging parts of the shock. The vortex flow is locally accelerated by the leading shock and locally decelerated by the lagging shock, having a severely elongated vortex core with two vertices. When the leading shock escapes the vortex, implosion effect creates a high pressure in the vertex area where the flow had been most expanded. This compressed region spreads in time with two frontal waves, an induced expansion wave and an induced compression wave. They are subsonic waves when the shock-vortex interaction is weak but become supersonic waves for strong interactions. Under a intermediate interaction, however, an induced shock wave is first developed where flow speed is supersonic but is dissipated where the incoming flow is subsonic. We have identified three different interaction patterns that depend on the vortex flow regime characterized by the shock-vortex interaction.

  17. Digital flight control research

    Science.gov (United States)

    Potter, J. E.; Stern, R. G.; Smith, T. B.; Sinha, P.

    1974-01-01

    The results of studies which were undertaken to contribute to the design of digital flight control systems, particularly for transport aircraft are presented. In addition to the overall design considerations for a digital flight control system, the following topics are discussed in detail: (1) aircraft attitude reference system design, (2) the digital computer configuration, (3) the design of a typical digital autopilot for transport aircraft, and (4) a hybrid flight simulator.

  18. Flight Standards Automation System -

    Data.gov (United States)

    Department of Transportation — FAVSIS supports Flight Standards Service (AFS) by maintaining their information on entities such as air carriers, air agencies, designated airmen, and check airmen....

  19. Noise reduction in supersonic jets by nozzle fluidic inserts

    Science.gov (United States)

    Morris, Philip J.; McLaughlin, Dennis K.; Kuo, Ching-Wen

    2013-08-01

    Professor Philip Doak spent a very productive time as a consultant to the Lockheed-Georgia Company in the early 1970s. The focus of the overall research project was the prediction and reduction of noise from supersonic jets. Now, 40 years on, the present paper describes an innovative methodology and device for the reduction of supersonic jet noise. The goal is the development of a practical active noise reduction technique for low bypass ratio turbofan engines. This method introduces fluidic inserts installed in the divergent wall of a CD nozzle to replace hard-wall corrugation seals, which have been demonstrated to be effective by Seiner (2005) [1]. By altering the configuration and operating conditions of the fluidic inserts, active noise reduction for both mixing and shock noise has been obtained. Substantial noise reductions have been achieved for mixing noise in the maximum noise emission direction and in the forward arc for broadband shock-associated noise. To achieve these reductions (on the order of greater than 4 and 2 dB for the two main components respectively), practically achievable levels of injection mass flow rates have been used. The total injected mass flow rates are less than 4% of the core mass flow rate and the effective operating injection pressure ratio has been maintained at or below the same level as the nozzle pressure ratio of the core flow.

  20. Instability of a supersonic shock free elliptic jet

    Energy Technology Data Exchange (ETDEWEB)

    Baty, R.S. (Sandia National Labs., Albuquerque, NM (USA)); Seiner, J.M.; Ponton, M.K. (National Aeronautics and Space Administration, Hampton, VA (USA). Langley Research Center)

    1990-01-01

    This paper presents a comparison of the measured and the computed spatial stability properties of an aspect ratio 2 supersonic shock free elliptic jet. The shock free nature of the elliptic jet provides an ideal test of validity of modeling the large scale coherent structures in the initial mixing region of noncircular supersonic jets with linear hydrodynamic stability theory. Both aerodynamic and acoustic data were measured. The data are used to compute the mean velocity profiles and to provide a description of the spatial composition of pressure waves in the elliptic jet. A hybrid numerical scheme is applied to solve the Rayleigh problem governing the inviscid linear spatial stability of the jet. The measured mean velocity profiles are used to provide a qualitative model for the cross sectional geometry and the smooth velocity profiles used in the stability analysis. Computational results are presented for several modes of instability at two jet cross sections. The acoustic measurements show that a varicose instability is the jet's perferred mode of motion. The stability analysis predicts that the Strouhal number varies linearly as a function of axial distance in the jet's initial mixing region, which is in good qualitative agreement with previous measurements. 18 refs., 18 figs., 1 tab.

  1. Super-Sonic Turbulence in the Perseus Molecular Cloud

    CERN Document Server

    Padoan, P; Billawala, Y N; Juvela, M; Nordlund, A A; Padoan, Paolo; Bally, John; Billawala, Youssef; Juvela, Mika; Nordlund, AAke

    1999-01-01

    We compare the statistical properties of J=1-0 13CO spectra observed in the Perseus Molecular Cloud with synthetic J=1-0 13CO spectra, computed solving the non-LTE radiative transfer problem for a model cloud obtained as solutions of the three dimensional magneto-hydrodynamic (MHD) equations. The model cloud is a randomly forced super-Alfvenic and highly super-sonic turbulent isothermal flow. The purpose of the present work is to test if idealized turbulent flows, without self-gravity, stellar radiation, stellar outflows, or any other effect of star formation, are inconsistent or not with statistical properties of star forming molecular clouds. We present several statistical results that demonstrate remarkable similarity between real data and the synthetic cloud. Statistical properties of molecular clouds like Perseus are appropriately described by random super-sonic and super-Alfvenic MHD flows. Although the description of gravity and stellar radiation are essential to understand the formation of single prot...

  2. Thermonuclear dynamo inside ultracentrifuge with supersonic plasma flow stabilization

    Energy Technology Data Exchange (ETDEWEB)

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

    2016-01-15

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

  3. a Continuous Supersonic Expansion Discharge Nozzle for Rotationally Cold Ions

    Science.gov (United States)

    Kauffman, Carrie A.; Crabtree, Kyle N.; McCall, Benjamin J.

    2009-06-01

    Molecular ions play an important role in chemistry and astronomy. In particular, molecular ions are key reaction intermediates, and in the interstellar medium, where temperatures and densities are low, they dominate the chemistry. Studying these ions spectroscopically in the laboratory poses a difficult challenge due to their reactivity. In our effort to study molecular ions, our research group is building SCRIBES (Sensitive Cooled Resolved Ion BEam Spectroscopy), which combines a cold ion source, mass spectrometry, and cavity ring-down spectroscopy. With this apparatus, we will be able to record rotationally-resolved gas-phase spectra, enabling interstellar searches for these species. The SCRIBES instrument requires a source of rotationally cold ions, and this has been accomplished by coupling a supersonic expansion with an electric discharge. Other groups (e.g. Thaddeus and McCarthy at Harvard, Salama et. al at NASA-Ames) have produced cold ions in a similar fashion, but always with a pulsed discharge source. Due to our need for a continuous ion source for SCRIBES, we have designed a continuous supersonic expansion discharge nozzle. We will discuss the various design factors considered during the construction of our continuous self-aligning cold ion source.

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

    Science.gov (United States)

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

    1986-01-01

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

  5. Supersonic Line Broadening within Young and Massive Super Star Clusters

    CERN Document Server

    Tenorio-Tagle, G; Silich, S; Munoz-Tunon, C; Palous, J

    2009-01-01

    The origin of supersonic infrared and radio recombination nebular lines often detected in young and massive superstar clusters are discussed. We suggest that these arise from a collection of repressurizing shocks (RSs), acting effectively to re-establish pressure balance within the cluster volume and from the cluster wind which leads to an even broader although much weaker component. The supersonic lines are here shown to occur in clusters that undergo a bimodal hydrodynamic solution (Tenorio-Tagle et al. 2007), that is within clusters that are above the threshold line in the mechanical luminosity or cluster mass vs the size of the cluster (Silich et al. 2004). The plethora of repressurizing shocks is due to frequent and recurrent thermal instabilities that take place within the matter reinserted by stellar winds and supernovae. We show that the maximum speed of the RSs and of the cluster wind, are both functions of the temperature reached at the stagnation radius. This temperature depends only on the cluster...

  6. Observation of supersonic turbulent wakes by laser Fourier densitometry (LFD)

    Science.gov (United States)

    Gresillon, D.; Cabrit, B.; Bonnet, J. P.; Gemaux, G.

    Laser Fourier Densitometry (LFD) is an optical method appropriate for turbulent flow observations. It uses the collective scattering of coherent light, by optical index inhomogeneities. The principle of this method is described. It provides a signal proportional to the space Fourier transform amplitude of index distribution for a wavevector k defined by the optical arrangement. For a fluctuating flow, this amplitude is a function of time, and its frequency spectrum can be observed. The spectrum shape provides elementary parameters of the flow, such as: direction, modulus of mean velocity, and local temperature. It also provides means to distinguish different kinds of density fluctuations, such as convected inhomogeneities, or acoustic waves. The respective level of these different fluctuations types can be measured, as well as their power scale-law and absolute level. A compact optical bench has been set on a nozzle flow. The results of measurements performed in two supersonic wake configurations are presented, for Mach numbers of 1.6 and 4.2. These include density fluctuation spectra in supersonic flows, acoustic waves, variations with position, and comparison with hot wire anemometry.

  7. Gas-Liquid Supersonic Cleaning and Cleaning Verification Spray System

    Science.gov (United States)

    Parrish, Lewis M.

    2009-01-01

    NASA Kennedy Space Center (KSC) recently entered into a nonexclusive license agreement with Applied Cryogenic Solutions (ACS), Inc. (Galveston, TX) to commercialize its Gas-Liquid Supersonic Cleaning and Cleaning Verification Spray System technology. This technology, developed by KSC, is a critical component of processes being developed and commercialized by ACS to replace current mechanical and chemical cleaning and descaling methods used by numerous industries. Pilot trials on heat exchanger tubing components have shown that the ACS technology provides for: Superior cleaning in a much shorter period of time. Lower energy and labor requirements for cleaning and de-scaling uper.ninih. Significant reductions in waste volumes by not using water, acidic or basic solutions, organic solvents, or nonvolatile solid abrasives as components in the cleaning process. Improved energy efficiency in post-cleaning heat exchanger operations. The ACS process consists of a spray head containing supersonic converging/diverging nozzles, a source of liquid gas; a novel, proprietary pumping system that permits pumping liquid nitrogen, liquid air, or supercritical carbon dioxide to pressures in the range of 20,000 to 60,000 psi; and various hoses, fittings, valves, and gauges. The size and number of nozzles can be varied so the system can be built in configurations ranging from small hand-held spray heads to large multinozzle cleaners. The system also can be used to verify if a part has been adequately cleaned.

  8. Structural concept trends for commercial supersonic cruise aircraft design

    Science.gov (United States)

    Sakat, I. F.; Davis, G. W.; Saelman, B.

    1980-01-01

    Structural concept trends for future commercial supersonic transport aircraft are considered. Highlights, including the more important design conditions and requirements, of two studies are discussed. Knowledge of these design parameters, as determined through studies involving the application of flexible mathematical models, enabled inclusion of aeroelastic considerations in the structural-material concepts evaluation. The design trends and weight data of the previous contractual study of Mach 2.7 cruise aircraft were used as the basis for incorporating advanced materials and manufacturing approaches to the airframe for reduced weight and cost. Structural studies of design concepts employing advanced aluminum alloys, advanced composites, and advanced titanium alloy and manufacturing techniques are compared for a Mach 2.0 arrow-wing configuration concept. Appraisals of the impact of these new materials and manufacturing concepts to the airframe design are shown and compared. The research and development to validate the potential sources of weight and cost reduction identified as necessary to attain a viable advanced commercial supersonic transport are discussed.

  9. Flow Simulation of Supersonic Inlet with Bypass Annular Duct

    Science.gov (United States)

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

    2011-01-01

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

  10. Communication: Equilibrium rate coefficients from atomistic simulations: The O({sup 3}P) + NO({sup 2}Π) → O{sub 2}(X{sup 3}Σ{sub g}{sup −}) + N({sup 4}S) reaction at temperatures relevant to the hypersonic flight regime

    Energy Technology Data Exchange (ETDEWEB)

    Castro-Palacio, Juan Carlos [Department of Chemistry, University of Basel, Klingelbergstrasse 80, 4056 Basel (Switzerland); Bemish, Raymond J. [Air Force Research Laboratory, Space Vehicles Directorate, Kirtland AFB, New Mexico 87117 (United States); Meuwly, Markus, E-mail: m.meuwly@unibas.ch [Department of Chemistry, University of Basel, Klingelbergstrasse 80, 4056 Basel (Switzerland); Department of Chemistry, Brown University, Providence, Rhode Island 02912 (United States)

    2015-03-07

    The O({sup 3}P) + NO({sup 2}Π) → O{sub 2}(X{sup 3}Σ{sub g}{sup −}) + N({sup 4}S) reaction is among the N- and O- involving reactions that dominate the energetics of the reactive air flow around spacecraft during hypersonic atmospheric re-entry. In this regime, the temperature in the bow shock typically ranges from 1000 to 20 000 K. The forward and reverse rate coefficients for this reaction derived directly from trajectory calculations over this range of temperature are reported in this letter. Results compare well with the established equilibrium constants for the same reaction from thermodynamic quantities derived from spectroscopy in the gas phase which paves the way for large-scale in silico investigations of equilibrium rates under extreme conditions.

  11. The january effect across volatility regimes

    OpenAIRE

    Agnani, Betty; Aray, Henry

    2007-01-01

    Using a Markov regime switching model, this article presents evidence on the well-known January effect on stock returns. The specification allows a distinction to be drawn between two regimes, one with high volatility and other with low volatility. We obtain a time-varying January effect that is, in general, positive and significant in both volatility regimes. However, this effect is larger in the high volatility regime. In sharp contrast with most previous literature we find two major result...

  12. Experimental and numerical investigation of an air to air supersonic ejector for propulsion of a small supersonic wind tunnel

    Directory of Open Access Journals (Sweden)

    Kracík Jan

    2015-01-01

    Full Text Available The article deals with experimental and numerical investigation of an air to air supersonic ejector with twelve primary nozzles. The ejector is supposed to be used for propulsion of a small experimental supersonic wind tunnel which is situated in laboratories of Technical University of Liberec. A novel arrangement with 12 primary nozzles is used. The nozzles are placed at the periphery of the mixing chamber. The secondary stream enters the ejector through the free centre of the mixing chamber and is sucked into the space between the primary nozzles. Moreover the declination of the primary nozzles towards to ejector axis is 8.2° and the shape of the mixing chamber and diffuser walls is given by normal cubic spline function, which was investigated in previous work. The declination of the primary nozzles is supposed to eliminate reversal flow in the centre of the mixing chamber. Experimental results for different numbers of simultaneously activated primary nozzles are carried out. Experimental results are compared to the numerical simulation made with the help of Ansys Fluent software.

  13. Implementation Regimes and Street-Level Bureaucrats

    DEFF Research Database (Denmark)

    Winter, Søren; T. Dinesen, Peter; J. May, Peter

    -government regimes foster greater policy commitment, attention to rules, and adherence among frontline workers than is the case for a local-government implementation regime. These lead to actions of street-level bureaucrats in central-government regimes that are more in line with national policies than those...

  14. Accommodating human values in the climate regime

    NARCIS (Netherlands)

    Cook, Rosalind; Tauschinsky, Eljalill

    2008-01-01

    The climate regime addresses one of the most important challenges facing humankind today. However, while the environmental and economic sides of the problem are well represented, it lacks the inclusion of social and human aspects. The human rights regime, in contrast, is a regime which has been esta

  15. Effect of intermolecular potential on compressible Couette flow in slip and transitional regimes

    Science.gov (United States)

    Weaver, Andrew B.; Venkattraman, A.; Alexeenko, Alina A.

    2014-10-01

    The effect of intermolecular potentials on compressible, planar flow in slip and transitional regimes is investigated using the direct simulation Monte Carlo method. Two intermolecular interaction models, the variable hard sphere (VHS) and the Lennard-Jones (LJ) models, are first compared for subsonic and supersonic Couette flows of argon at temperatures of 40, 273, and 1,000 K, and then for Couette flows in the transitional regime ranging from Knudsen numbers (Kn) of 0.0051 to 1. The binary scattering model for elastic scattering using the Lennard-Jones (LJ) intermolecular potential proposed recently [A. Venkattraman and A. Alexeenko, "Binary scattering model for Lennard-Jones potential: Transport coefficients and collision integrals for non-equilibrium gas flow simulations," Phys. Fluids 24, 027101 (2012)] is shown to accurately reproduce both the theoretical collision frequency in an equilibrium gas as well as the theoretical viscosity variation with temperature. The use of a repulsive-attractive instead of a purely repulsive potential is found to be most important in the continuum and slip regimes as well as in flows with large temperature variations. Differences in shear stress of up to 28% between the VHS and LJ models is observed at Kn=0.0051 and is attributed to differences in collision frequencies, ultimately affecting velocity gradients at the wall. For Kn=1 where the Knudsen layer expands the entire domain, the effect of the larger collision frequency in the LJ model relative to VHS diminishes, and a 7% difference in shear stress is observed.

  16. Long-term space flights - personal impressions

    Science.gov (United States)

    Polyakov, V. V.

    During a final 4-month stage of a 1-year space flight of cosmonauts Titov and Manarov, a physician, Valery Polyakov was included on a crew for the purpose of evaluating their health, correcting physical status to prepare for the spacecraft reentry and landing operations. The complex program of scientific investigations and experiments performed by the physician included an evaluation of adaptation reactions of the human body at different stages of space mission using clinicophysiological and biochemical methods; testing of alternative regimes of exercise and new countermeasures to prevent an unfavourable effect of long-term weightlessness.

  17. Electromechanical flight control actuator

    Science.gov (United States)

    1979-01-01

    The feasibility of using an electromechanical actuator (EMA) as the primary flight control equipment in aerospace flight is examined. The EMA motor design is presented utilizing improved permanent magnet materials. The necessary equipment to complete a single channel EMA using the single channel power electronics breadboard is reported. The design and development of an improved rotor position sensor/tachometer is investigated.

  18. Java for flight software

    Science.gov (United States)

    Benowitz, E.; Niessner, A.

    2003-01-01

    This work involves developing representative mission-critical spacecraft software using the Real-Time Specification for Java (RTSJ). This work currently leverages actual flight software used in the design of actual flight software in the NASA's Deep Space 1 (DSI), which flew in 1998.

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

    Science.gov (United States)

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

    1983-01-01

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

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

    DEFF Research Database (Denmark)

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

    2016-01-01

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

  1. Adaptation in Collaborative Governance Regimes

    Science.gov (United States)

    Emerson, Kirk; Gerlak, Andrea K.

    2014-10-01

    Adaptation and the adaptive capacity of human and environmental systems have been of central concern to natural and social science scholars, many of whom characterize and promote the need for collaborative cross-boundary systems that are seen as flexible and adaptive by definition. Researchers who study collaborative governance systems in the public administration, planning and policy literature have paid less attention to adaptive capacity specifically and institutional adaptation in general. This paper bridges the two literatures and finds four common dimensions of capacity, including structural arrangements, leadership, knowledge and learning, and resources. In this paper, we focus on institutional adaptation in the context of collaborative governance regimes and try to clarify and distinguish collaborative capacity from adaptive capacity and their contributions to adaptive action. We posit further that collaborative capacities generate associated adaptive capacities thereby enabling institutional adaptation within collaborative governance regimes. We develop these distinctions and linkages between collaborative and adaptive capacities with the help of an illustrative case study in watershed management within the National Estuary Program.

  2. Radiative forcing from particle emissions by future supersonic aircraft

    Directory of Open Access Journals (Sweden)

    G. Pitari

    2008-07-01

    Full Text Available In this work we focus on the direct radiative forcing (RF of black carbon (BC and sulphuric acid particles emitted by future supersonic aircraft, as well as on the ozone RF due to changes produced by emissions of both gas species (NOx, H2O and aerosol particles capable of affecting stratospheric ozone chemistry. Heterogeneous chemical reactions on the surface of sulphuric acid stratospheric particles (SSA-SAD are the main link between ozone chemistry and supersonic aircraft emissions of sulphur precursors (SO2 and particles (H2O–H2SO4. Photochemical O3 changes are compared from four independent 3-D atmosphere-chemistry models (ACMs, using as input the perturbation of SSA-SAD calculated in the University of L'Aquila model, which includes on-line a microphysics code for aerosol formation and growth. The ACMs in this study use aircraft emission scenarios for the year 2050 developed by AIRBUS as a part of the EU project SCENIC, assessing options for fleet size, engine technology (NOx emission index, Mach number, range and cruising altitude. From our baseline modeling simulation, the impact of supersonic aircraft on sulphuric acid aerosol and BC mass burdens is 53 and 1.5 μg/m2, respectively, with a direct RF of −11.4 and 4.6 mW/m2 (net RF=−6.8 mW/m2. This paper discusses the similarities and differences amongst the participating models in terms of changes to O3 precursors due to aircraft emissions (NOx, HOx,Clx,Brx and the stratospheric ozone sensitivity to them. In the baseline case, the calculated global ozone change is −0.4 ±0.3 DU, with a net radiative forcing (IR+UV of −2.5± 2 mW/m2. The fraction of this O3-RF attributable to SSA-SAD changes is, however, highly variable among the models, depending on the NOx removal

  3. Measuring the effectiveness of international environmental regimes

    Energy Technology Data Exchange (ETDEWEB)

    Helm, C.; Sprinz, D.F.

    1999-05-01

    While past research has emphasized the importance of international regimes for international governance, systematic assessments of regime effects are missing. This article derives a standardized measurement concept for the effectiveness of international environmental regimes by developing an operational rational choice calculus to evaluate actual policy simultaneously against a non-regime counterfactual and a collective optimum. Subsequently, the empirical feasibility of the measurement instrument is demonstrated by way of two international treaties regulating transboundary air pollution in Europe. The results demonstrate that the regimes indeed show positive effects - but fall substantially short of the collective optima. (orig.)

  4. Performance of Several High Order Numerical Methods for Supersonic Combustion

    Science.gov (United States)

    Sjoegreen, Bjoern; Yee, H. C.; Don, Wai Sun; Mansour, Nagi N. (Technical Monitor)

    2001-01-01

    The performance of two recently developed numerical methods by Yee et al. and Sjoegreen and Yee using postprocessing nonlinear filters is examined for a 2-D multiscale viscous supersonic react-live flow. These nonlinear filters can improve nonlinear instabilities and at the same time can capture shock/shear waves accurately. They do not, belong to the class of TVD, ENO or WENO schemes. Nevertheless, they combine stable behavior at discontinuities and detonation without smearing the smooth parts of the flow field. For the present study, we employ a fourth-order Runge-Kutta in time and a sixth-order non-dissipative spatial base scheme for the convection and viscous terms. We denote the resulting nonlinear filter schemes ACM466-RK4 and WAV66-RK4.

  5. Optical wavefront distortion due to supersonic flow fields

    Institute of Scientific and Technical Information of China (English)

    CHEN ZhiQiang; FU Song

    2009-01-01

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

  6. Supersonic jets of hydrogen and helium for laser wakefield acceleration

    CERN Document Server

    Svensson, K.; Wojda, F.; Senje, L.; Burza, M.; Aurand, B.; Genoud, G.; Persson, A.; Wahlström, C.-G.; Lundh, O.

    2016-01-01

    The properties of laser wakefield accelerated electrons in supersonic gas flows of hydrogen and helium are investigated. At identical backing pressure, we find that electron beams emerging from helium show large variations in their spectral and spatial distributions, whereas electron beams accelerated in hydrogen plasmas show a higher degree of reproducibility. In an experimental investigation of the relation between neutral gas density and backing pressure, it is found that the resulting number density for helium is ∼30% higher than for hydrogen at the same backing pressure. The observed differences in electron beam properties between the two gases can thus be explained by differences in plasma electron density. This interpretation is verified by repeating the laser wakefield acceleration experiment using similar plasma electron densities for the two gases, which then yielded electron beams with similar properties.

  7. Survey of supersonic combustion ramjet research at Langley

    Science.gov (United States)

    Northam, G. B.; Anderson, G. Y.

    1986-01-01

    The Hypersonic Propulsion Branch at NASA Langley Research Center has maintained an active research program in supersonic combustion ramjet (scramjet) and high speed ramjet propulsion since the 1960s. The focus for this research has centered on propulsion for manned reuseable vehicles with cryogenic hydrogen fuel. This paper presents some highlights of this research. The design philosophy of the Langley fixed-geometry airframe-integrated modular scramjet is discussed. The component development and research programs that have supported the successful demonstration of the engine concept using subscale engine module hardware is reviewed and a brief summary of the engine tests presented. An extensive bibliography of research supported by the Langley program is also included.

  8. Survey of supersonic combustion ramjet research at Langley

    Science.gov (United States)

    Northam, G. B.; Anderson, G. Y.

    1986-01-01

    The Hypersonic Propulsion Branch at NASA Langley Research Center has maintained an active research program in supersonic combustion ramjet (scramjet) and high speed ramjet propulsion since the 1960s. The focus for this research has centered on propulsion for manned reuseable vehicles with cryogenic hydrogen fuel. This paper presents some highlights of this research. The design philosophy of the Langley fixed-geometry airframe-integrated modular scramjet is discussed. The component development and research programs that have supported the successful demonstration of the engine concept using subscale engine module hardware is reviewed and a brief summary of the engine tests presented. An extensive bibliography of research supported by the Langley program is also included.

  9. Dissipation and Heating in Supersonic Hydrodynamic and MHD Turbulence

    CERN Document Server

    Lemaster, M Nicole

    2008-01-01

    We study energy dissipation and heating by supersonic MHD turbulence in molecular clouds using Athena, a new higher-order Godunov code. We analyze the dependence of the saturation amplitude, energy dissipation characteristics, power spectra, sonic scaling, and indicators of intermittency in the turbulence on factors such as the magnetic field strength, driving scale, energy injection rate, and numerical resolution. While convergence in the energies is reached at moderate resolutions, we find that the power spectra require much higher resolutions that are difficult to obtain. In a 1024^3 hydro run, we find a power law relationship between the velocity dispersion and the spatial scale on which it is measured, while for an MHD run at the same resolution we find no such power law. The time-variability and temperature intermittency in the turbulence both show a dependence on the driving scale, indicating that numerically driving turbulence by an arbitrary mechanism may not allow a realistic representation of these...

  10. Vortex development on slender missiles at supersonic speeds

    Science.gov (United States)

    Allen, J. M.; Dillenius, M. F. E.

    1979-01-01

    A theoretical and experimental effort has been made to develop a vortex-prediction capability on circular and noncircular missiles at supersonic speeds. Predicted vortex patterns are computed by two linear-theory computer codes. One calculates the strengths and initial locations of the vortices, and the other calculates their trajectories. A short color motion picture has been produced from the calculations to illustrate the predicted vortex patterns on a typical missile. Experimental vapor-screen photographs are presented to show the longitudinal development of the vortices on a fin-control missile. Comparisons are made between these data and the predicted vortices to assess the accuracy of the theory. The theory appears to be fairly accurate in predicting the number, locations, and relative strengths of individual vortices which develop over the missile, but cannot predict vortex sheets or diffuse vorticity whenever they occur.

  11. Gas dynamics of a supersonic radial jet. Part II

    Science.gov (United States)

    Kosarev, V. F.; Klinkov, S. V.; Zaikovskii, V. N.

    2016-05-01

    The paper presents the radial distributions of the pressure measured with a Pitot tube for the case of a radial jet with/without swirling of the input flow in the pre-chamber; the length of the supersonic part of the jet, dependency of the jet thickness as a function of the distance from the nozzle outlet, and approximating analytical formula for the jet thickness that generalizes the experimental data. Experimental data demonstrated that at the deposition distances lower than 4-6 gauges from the nozzle outlet, the solid particle velocity and temperature are almost uniform over the jet cross section. This means that the target surface can be allocated here without loss in coating quality and deposition coefficient. The maximal recommended distance where the deposition is still possible is the length of l s0 ~ 16 gauges.

  12. Supersonic flutter analysis of thin cracked functionally graded material plates

    CERN Document Server

    Natarajan, S; Bordas, S

    2012-01-01

    In this paper, the flutter behaviour of simply supported square functionally graded material plates immersed in a supersonic flow is studied. An enriched 4-noded quadrilateral element based on field consistency approach is used for this study and the crack is modelled independent of the underlying mesh. The material properties are assumed to be temperature dependent and graded only in the thickness direction. The effective material properties are estimated using the rule of mixtures. The formulation is based on the first order shear deformation theory and the shear correction factors are evaluated employing the energy equivalence principle. The influence of the crack length, the crack orientation, the flow angle and the gradient index on the aerodynamic pressure and the frequency are numerically studied. The results obtained here reveal that the critical frequency and the critical pressure decreases with increase in crack length and it is minimum when the crack is aligned to the flow angle.

  13. Modeling supersonic combustion using a fully-implicit numerical method

    Science.gov (United States)

    Maccormack, Robert W.; Wilson, Gregory J.

    1990-01-01

    A fully-implicit finite-volume algorithm for two-dimensional axisymmetric flows has been coupled to a detailed hydrogen-air reaction mechanism (13 species and 33 reactions) so that supersonic combustion phenomena may be investigated. Numerical computations are compared with ballistic-range shadowgraphs of Lehr (1972) that exhibit two discontinuities caused by a blunt body as it passes through a premixed stoichiometric hydrogen-air mixture. The suitability of the numerical procedure for simulating these double-front flows is shown. The requirements for the physical formulation and the numerical modeling of these flowfields are discussed. Finally, the sensitivity of these external flowfields to changes in certain key reaction rate constants is examined.

  14. Nonlinear closures for scale separation in supersonic magnetohydrodynamic turbulence

    CERN Document Server

    Grete, Philipp; Schmidt, Wolfram; Schleicher, Dominik R G; Federrath, Christoph

    2015-01-01

    Turbulence in compressible plasma plays a key role in many areas of astrophysics and engineering. The extreme plasma parameters in these environments, e.g. high Reynolds numbers, supersonic and super-Alfvenic flows, however, make direct numerical simulations computationally intractable even for the simplest treatment -- magnetohydrodynamics (MHD). To overcome this problem one can use subgrid-scale (SGS) closures -- models for the influence of unresolved, subgrid-scales on the resolved ones. In this work we propose and validate a set of constant coefficient closures for the resolved, compressible, ideal MHD equations. The subgrid-scale energies are modeled by Smagorinsky-like equilibrium closures. The turbulent stresses and the electromotive force (EMF) are described by expressions that are nonlinear in terms of large scale velocity and magnetic field gradients. To verify the closures we conduct a priori tests over 137 simulation snapshots from two different codes with varying ratios of thermal to magnetic pre...

  15. Overexpanded viscous supersonic jet interacting with a unilateral barrier

    Science.gov (United States)

    Dobrynin, B. M.; Maslennikov, V. G.; Sakharov, V. A.; Serova, E. V.

    1986-07-01

    The interaction of a two-dimensional supersonic jet with a unilateral barrier parallel to the flow symmetry plane was studied to account for effects due to gas viscosity and backgound-gas ejection from the region into which the jet expands. In the present experiments, the incident shock wave was reflected at the end of a shock tube equipped with a nozzle. The jet emerged into a pressure chamber 6 cu m in volume and the environmental pressure ratio of the flow in the quasi-stationary phase remained constant. The light source was an OGM-20 laser operating in the giant-pulse mode. Due to background-gas ejection, the gas density in the vicinity of the barrier is much less than on the unconfined side of the jet. The resulting flow is characterized by two distinct environmental pressure ratios: the flow is underexpanded near the barrier, while on the other side it is overexpanded.

  16. Supersonic Relative Velocity Effect on the Baryonic Acoustic Oscillation Measurements

    CERN Document Server

    Yoo, Jaiyul; Seljak, Uros

    2011-01-01

    We investigate the effect of supersonic relative velocities between baryons and dark matter, recently shown to arise generically at high redshift, on baryonic acoustic oscillation (BAO) measurements at low redshift. The amplitude of the relative velocity effect at low redshift is model-dependent, but can be parameterized by using an unknown bias. We find that if unaccounted, the relative velocity effect can shift the BAO peak position and bias estimates of the dark energy equation-of-state due to its non-smooth, out-of-phase oscillation structure around the BAO scale. Fortunately, the relative velocity effect can be easily modeled in constraining cosmological parameters without substantially inflating the error budget. We also demonstrate that the presence of the relative velocity effect gives rise to a unique signature in the galaxy bispectrum, which can be utilized to isolate this effect. Future dark energy surveys can accurately measure the relative velocity effect and subtract it from the power spectrum a...

  17. Comparing Numerical Methods for Isothermal Magnetized Supersonic Turbulence

    CERN Document Server

    Kritsuk, Alexei G; Collins, David; Padoan, Paolo; Norman, Michael L; Abel, Tom; Banerjee, Robi; Federrath, Christoph; Flock, Mario; Lee, Dongwook; Li, Pak Shing; Mueller, Wolf-Christian; Teyssier, Romain; Ustyugov, Sergey D; Vogel, Christian; Xu, Hao

    2011-01-01

    We employ simulations of supersonic super-Alfv\\'enic turbulence decay as a benchmark test problem to assess and compare the performance of nine astrophysical MHD methods actively used to model star formation. The set of nine codes includes: ENZO, FLASH, KT-MHD, LL-MHD, PLUTO, PPML, RAMSES, STAGGER, and ZEUS. We present a comprehensive set of statistical measures designed to quantify the effects of numerical dissipation in these MHD solvers. We compare power spectra for basic fields to determine the effective spectral bandwidth of the methods and rank them based on their relative effective Reynolds numbers. We also compare numerical dissipation for solenoidal and dilatational velocity components to check for possible impacts of the numerics on small-scale density statistics. Finally, we discuss convergence of various characteristics for the turbulence decay test and impacts of various components of numerical schemes on the accuracy of solutions. We show that the best performing codes employ a consistently high...

  18. High-frequency supersonic heating of hydrogen for propulsion

    Energy Technology Data Exchange (ETDEWEB)

    Bonneville, Jacques M.

    1963-03-15

    The possibility of increasing the specific impulse of hydrogen by supersonic heating is shown on the basis of thermodynamics. The application of high-frequency electric fields to heat the gas permits a control over the heating rates in the nozzle, and results in a reduction in energy losses to walls, electrodes, etc. The efficiencies of the various energy transfer processes are considered in some detail. A simple process of expansion and heating is presented. Results of calculations of heat transfer rates to the nozzle wall are given. A consistent set of electron densities and electric fields are also calculated and presented. Some qualitative results of experimental work previously carried out are included. It is concluded that the process should increase the specific impulse of hydrogen appreciably, in a reasonably efficient manner, and that further experimental work is indicated. (auth)

  19. Fluid-structure interaction of panel in supersonic fluid passage

    Institute of Scientific and Technical Information of China (English)

    LIU Zhan-sheng; ZHANG Yun-feng; TIAN Xin

    2008-01-01

    Fluid-structure interaction of panel in supersonic fluid passage is studied with subcycling and spline interpolation based predict-correct scheme.The passage is formed with two parallel panels,one is risid and the other is flexible.The interaction between fluid flows and flexible panel is numerically studied,mainly focused on the effect of dynamic pressure and distance between two parallel panels.Subcycling and spline interpolation based predict-correct scheme is utihzed to combine the vibration and fluid analysis and to stabilize long-term calculations to get accurate resuhs.It's demonstrated that the flutter characteristic of flexible panel is more complex with the increase of dynamic pressure and the decrease of distance between two parallel panels.Via analyzing the propagation and reflection of disturbance in passage,it's determined as a main cause of the variations.

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

    Directory of Open Access Journals (Sweden)

    Chenxi Wu

    2014-01-01

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

  1. Airborne Turbulence Detection and Warning ACLAIM Flight Test Results

    Science.gov (United States)

    Hannon, Stephen M.; Bagley, Hal R.; Soreide, Dave C.; Bowdle, David A.; Bogue, Rodney K.; Ehernberger, L. Jack

    1999-01-01

    The Airborne Coherent Lidar for Advanced Inflight Measurements (ACLAIM) is a NASA/Dryden-lead program to develop and demonstrate a 2 micrometers pulsed Doppler lidar for airborne look-ahead turbulence detection and warning. Advanced warning of approaching turbulence can significantly reduce injuries to passengers and crew aboard commercial airliners. The ACLAIM instrument is a key asset to the ongoing Turbulence component of NASA's Aviation Safety Program, aimed at reducing the accident rate aboard commercial airliners by a factor of five over the next ten years and by a factor of ten over the next twenty years. As well, the advanced turbulence warning capability can prevent "unstarts" in the inlet of supersonic aircraft engines by alerting the flight control computer which then adjusts the engine to operate in a less fuel efficient, and more turbulence tolerant, mode. Initial flight tests of the ACLAIM were completed in March and April of 1998. This paper and presentation gives results from these initial flights, with validated demonstration of Doppler lidar wind turbulence detection several kilometers ahead of the aircraft.

  2. Magnesium and Space Flight

    Science.gov (United States)

    Smith, Scott M.; Zwart, Sara R.

    2016-01-01

    Magnesium is an essential nutrient for muscle, cardiovascular, and bone health on Earth, and during space flight. We sought to evaluate magnesium status in astronauts before, during, and after space missions, in 43 astronauts (34 male, 9 female) on 4-6 month space flight missions. We also studied individuals participating in a ground analog of space flight, (head-down tilt bed rest, n=27, 35 +/- 7 y). We evaluated serum concentration and 24-hour urinary excretion of magnesium along with estimates of tissue magnesium status from sublingual cells. Serum magnesium increased late in flight, while urinary magnesium excretion was higher over the course of 180-d space missions. Urinary magnesium increased during flight but decreased significantly at landing. Neither serum nor urinary magnesium changed during bed rest. For flight and bed rest, significant correlations existed between the area under the curve of serum and urinary magnesium and the change in total body bone mineral content. Tissue magnesium concentration was unchanged after flight and bed rest. Increased excretion of magnesium is likely partially from bone and partially from diet, but importantly, it does not come at the expense of muscle tissue stores. While further study is needed to better understand the implications of these findings for longer space exploration missions, magnesium homeostasis and tissue status seem well maintained during 4- to 6-month space missions.

  3. Supersonic Stall Flutter of High Speed Fans. [in turbofan engines

    Science.gov (United States)

    Adamczyk, J. J.; Stevens, W.; Jutras, R.

    1981-01-01

    An analytical model is developed for predicting the onset of supersonic stall bending flutter in axial flow compressors. The analysis is based on a modified two dimensional, compressible, unsteady actuator disk theory. It is applied to a rotor blade row by considering a cascade of airfoils whose geometry and dynamic response coincide with those of a rotor blade element at 85 percent of the span height (measured from the hub). The rotor blades are assumed to be unshrouded (i.e., free standing) and to vibrate in their first flexural mode. The effects of shock waves and flow separation are included in the model through quasi-steady, empirical, rotor total-pressure-loss and deviation-angle correlations. The actuator disk model predicts the unsteady aerodynamic force acting on the cascade blading as a function of the steady flow field entering the cascade and the geometry and dynamic response of the cascade. Calculations show that the present model predicts the existence of a bending flutter mode at supersonic inlet Mach numbers. This flutter mode is suppressed by increasing the reduced frequency of the system or by reducing the steady state aerodynamic loading on the cascade. The validity of the model for predicting flutter is demonstrated by correlating the measured flutter boundary of a high speed fan stage with its predicted boundary. This correlation uses a level of damping for the blade row (i.e., the log decrement of the rotor system) that is estimated from the experimental flutter data. The predicted flutter boundary is shown to be in good agreement with the measured boundary.

  4. Chirped Pulse Microwave Spectroscopy in Pulsed Uniform Supersonic Flows

    Science.gov (United States)

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

    2014-06-01

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

  5. 超音速靶机的总体设计与研究%Conceptual Design and Reserch of Supersonic Target Drone

    Institute of Scientific and Technical Information of China (English)

    刘靖; 刘志强

    2016-01-01

    According to the requirements of test and evaluation of weapon system, the general tech-nology requirements were put forward. The conceptual design of supersonic target drone on the aircraft design procedure was finished. The dynamic system, aerodynamic configuration and aerodynamic charac-teristics were designed in detail. The main flight performance was calculated. The foundation of engineer-ing implementation for the supersonic target drone has laid by the conceptual design.%根据武器系统试验需求,提出了超音速靶机的总体技术要求。按照飞行器设计的基本流程,完成了某型超音速靶机的总体设计,对该型靶机的动力系统、气动布局、气动特性等方面进行了详细设计,并对主要飞行性能进行了计算,为超音速靶机的工程实现打下了基础。

  6. Analysis of the Effects of Thermal Environment on Optical Systems for Navigation Guidance and Control in Supersonic Aircraft Based on Empirical Equations

    Directory of Open Access Journals (Sweden)

    Xuemin Cheng

    2016-10-01

    Full Text Available The thermal environment is an important factor in the design of optical systems. This study investigated the thermal analysis technology of optical systems for navigation guidance and control in supersonic aircraft by developing empirical equations for the front temperature gradient and rear thermal diffusion distance, and for basic factors such as flying parameters and the structure of the optical system. Finite element analysis (FEA was used to study the relationship between flying and front dome parameters and the system temperature field. Systematic deduction was then conducted based on the effects of the temperature field on the physical geometry and ray tracing performance of the front dome and rear optical lenses, by deriving the relational expressions between the system temperature field and the spot size and positioning precision of the rear optical lens. The optical systems used for navigation guidance and control in supersonic aircraft when the flight speed is in the range of 1–5 Ma were analysed using the derived equations. Using this new method it was possible to control the precision within 10% when considering the light spot received by the four-quadrant detector, and computation time was reduced compared with the traditional method of separately analysing the temperature field of the front dome and rear optical lens using FEA. Thus, the method can effectively increase the efficiency of parameter analysis and computation in an airborne optical system, facilitating the systematic, effective and integrated thermal analysis of airborne optical systems for navigation guidance and control.

  7. Analysis of the Effects of Thermal Environment on Optical Systems for Navigation Guidance and Control in Supersonic Aircraft Based on Empirical Equations.

    Science.gov (United States)

    Cheng, Xuemin; Yang, Yikang; Hao, Qun

    2016-10-17

    The thermal environment is an important factor in the design of optical systems. This study investigated the thermal analysis technology of optical systems for navigation guidance and control in supersonic aircraft by developing empirical equations for the front temperature gradient and rear thermal diffusion distance, and for basic factors such as flying parameters and the structure of the optical system. Finite element analysis (FEA) was used to study the relationship between flying and front dome parameters and the system temperature field. Systematic deduction was then conducted based on the effects of the temperature field on the physical geometry and ray tracing performance of the front dome and rear optical lenses, by deriving the relational expressions between the system temperature field and the spot size and positioning precision of the rear optical lens. The optical systems used for navigation guidance and control in supersonic aircraft when the flight speed is in the range of 1-5 Ma were analysed using the derived equations. Using this new method it was possible to control the precision within 10% when considering the light spot received by the four-quadrant detector, and computation time was reduced compared with the traditional method of separately analysing the temperature field of the front dome and rear optical lens using FEA. Thus, the method can effectively increase the efficiency of parameter analysis and computation in an airborne optical system, facilitating the systematic, effective and integrated thermal analysis of airborne optical systems for navigation guidance and control.

  8. Air-Launch TSTO With Subsonic In-Flight Collection-System and Technology Study

    Science.gov (United States)

    2007-11-02

    glider based on the FDL-7 series of hypersonic gliders developed and tested by A. Draper and M. Buck at the Flight Dynamics Laboratory in the ‘70’s...lot of kilograms and specific weight may be increased by a factor 2 to 2.5. By comparison, collecting at high supersonic / low hypersonic conditions...The vehicle of figure 4.7 is not a winged-cylindrical body configuration like on figure 4.8. It is a very efficient rocket-derived powered hypersonic

  9. Hall effect in hopping regime

    Energy Technology Data Exchange (ETDEWEB)

    Avdonin, A., E-mail: avdonin@ifpan.edu.pl [Institute of Physics, Polish Academy of Sciences, Al. Lotników 32/46, 02-668 Warszawa (Poland); Skupiński, P. [Institute of Physics, Polish Academy of Sciences, Al. Lotników 32/46, 02-668 Warszawa (Poland); Grasza, K. [Institute of Physics, Polish Academy of Sciences, Al. Lotników 32/46, 02-668 Warszawa (Poland); Institute of Electronic Materials Technology, ul. Wólczyńska 133, 01-919 Warszawa (Poland)

    2016-02-15

    A simple description of the Hall effect in the hopping regime of conductivity in semiconductors is presented. Expressions for the Hall coefficient and Hall mobility are derived by considering averaged equilibrium electron transport in a single triangle of localization sites in a magnetic field. Dependence of the Hall coefficient is analyzed in a wide range of temperature and magnetic field values. Our theoretical result is applied to our experimental data on temperature dependence of Hall effect and Hall mobility in ZnO. - Highlights: • Expressions for Hall coefficient and mobility for hopping conductivity are derived. • Theoretical result is compared with experimental curves measured on ZnO. • Simultaneous action of free and hopping conduction channels is considered. • Non-linearity of hopping Hall coefficient is predicted.

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

    Institute of Scientific and Technical Information of China (English)

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

    2006-01-01

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

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

    Science.gov (United States)

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

    1978-01-01

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

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

    Science.gov (United States)

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

    1977-01-01

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

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

    CSIR Research Space (South Africa)

    Meijer, M-C

    2015-08-01

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

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

    Institute of Scientific and Technical Information of China (English)

    2009-01-01

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

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

    Science.gov (United States)

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

    2017-03-01

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

  16. Energy-Deposition to Reduce Skin Friction in Supersonic Applications Project

    Data.gov (United States)

    National Aeronautics and Space Administration — NASA has drawn attention to an impending need to improve energy-efficiency in low supersonic (M<~3) platforms. Aerodynamic efficiency is the foundation of...

  17. Experimental Investigation on Noise Suppression in Supersonic Jets from Convergent-Divergent Nozzles with Baffles

    Institute of Scientific and Technical Information of China (English)

    Yoshiaki Miyazato; Yong-Hun Kweon; Toshiyuki Aoki; Mitsuharu Masuda; Kwon-Hee Lee; Heuy-Dong Kim; Toshiaki Setoguchi; Kazuyasu Matsuo

    2003-01-01

    The acoustic properties of supersonic jet noise from a convergent-divergent nozzle with a baffle have been studied experimentally over the range of nozzle pressure ratios from 2.0 to 8.0. Acoustic measurements were conducted in a carefully designed anechoic room providing a free-field environment. A new approach for screech noise suppression by a cross-wire is proposed. Schlieren photographs were taken to visualize the shock wave patterns in the supersonic jet with and without the cross-wire. The effects of the baffle and the cross-wire on acoustic properties are discussed. It is shown that the baffle has little effect on the screech frequency for the underexpanded supersonic jet without the cross-wire. Also, the cross-wire introduced in supersonic jets is found to lead to a significant reduction in overall sound pressure level.

  18. Sting Supported Bell XS-2 in the 9 Inch Supersonic Tunnel

    Science.gov (United States)

    1947-01-01

    A sting supported model of the Bell XS-2 was tested in the 9 Inch Supersonic Tunnel. Photograph published in Engineer in Charge: A History of the Langley Aeronautical Laboratory, 1917-1958 by James R. Hansen. Page 316.

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

    Institute of Scientific and Technical Information of China (English)

    ToshiakiSetoguchi; ShenYu; 等

    1997-01-01

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

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

    Institute of Scientific and Technical Information of China (English)

    HideoKashimura; ShenYu; 等

    1998-01-01

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

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

    Institute of Scientific and Technical Information of China (English)

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

    2009-01-01

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

  2. Initial Flight Test of the Production Support Flight Control Computers at NASA Dryden Flight Research Center

    Science.gov (United States)

    Carter, John; Stephenson, Mark

    1999-01-01

    The NASA Dryden Flight Research Center has completed the initial flight test of a modified set of F/A-18 flight control computers that gives the aircraft a research control law capability. The production support flight control computers (PSFCC) provide an increased capability for flight research in the control law, handling qualities, and flight systems areas. The PSFCC feature a research flight control processor that is "piggybacked" onto the baseline F/A-18 flight control system. This research processor allows for pilot selection of research control law operation in flight. To validate flight operation, a replication of a standard F/A-18 control law was programmed into the research processor and flight-tested over a limited envelope. This paper provides a brief description of the system, summarizes the initial flight test of the PSFCC, and describes future experiments for the PSFCC.

  3. The Intensity of the Light Diffraction by Supersonic Longitudinal Waves in Solid

    Directory of Open Access Journals (Sweden)

    Minasyan V.

    2010-04-01

    Full Text Available First, we predict existence of transverse electromagnetic field created by supersonic longitudinal waves in solid. This electromagnetic wave with frequency of ultrasonic field is moved by velocity of supersonic field toward of direction propagation of one. The average Poynting vector of superposition field is calculated by presence of the transverse electromagnetic and the optical fields which in turn provides appearance the diffraction of light.

  4. Aerodynamic Optimization of a Supersonic Bending Body Projectile by a Vector-Evaluated Genetic Algorithm

    Science.gov (United States)

    2016-12-01

    ARL-CR-0810 ● DEC 2016 US Army Research Laboratory Aerodynamic Optimization of a Supersonic Bending Body Projectile by a Vector...not return it to the originator. ARL-CR-0810 ● DEC 2016 US Army Research Laboratory Aerodynamic Optimization of a ...Supersonic Bending Body Projectile by a Vector-Evaluated Genetic Algorithm prepared by Justin L Paul Academy of Applied Science 24 Warren Street

  5. Flight Research Building (Hangar)

    Data.gov (United States)

    Federal Laboratory Consortium — The NASA Glenn Flight Research Building is located at the NASA Glenn Research Center with aircraft access to Cleveland Hopkins International Airport. The facility is...

  6. Hypersonic flight testing

    Energy Technology Data Exchange (ETDEWEB)

    Williamson, W.

    1987-01-01

    This presentation is developed for people attending the University of Texas week-long short course in hypersonics. The presentation will be late in the program after the audience has been exposed to computational tehniques and ground test methods. It will attempt to show why we flight test, flight test options, what we learn from flight tests and how we use this information to improve our knowledge of hypersonics. It presupposes that our primary interest is in developing vehicles which will fly in the hypersonic flight region and not in simply developing technology for technology's sake. The material is presented in annotated vugraph form so that the author's comments on each vugraph are on the back of the preceding page. It is hoped that the comments will help reinforce the message on the vugraph.

  7. Flight Systems Monitor Project

    Data.gov (United States)

    National Aeronautics and Space Administration — This SBIR Phase I project will develop the Flight System Monitor which will use non-intrusive electrical monitoring (NEMO). The electronic system health of...

  8. 超-超引射器多目标优化设计%Multi-objective optimization of supersonic-supersonic ejector

    Institute of Scientific and Technical Information of China (English)

    陈钦; 陈吉明; 蔡光明; 任泽斌

    2012-01-01

    推导出了超-超引射器性能计算和优化设计模型,借助Pareto优胜、Pareto最优解和Pareto前端等概念,采用基于多目标进化/分解算法(MOEA/D)的多目标优化方法,计算得到超-超引射器多目标优化问题的Pareto前端,解决了超-超引射器多目标优化设计问题,并与常规参数分析方法进行了比较.结果表明:超超引射器性能影响参数相互关系复杂,增压比和引射系数作为引射器主要性能参数相互冲突,通过常规分析难以得到较清晰的设计准则,利用多目标优化设计方法可有效地辅助多属性决策和系统优化设计.%For supersonic-supersonic ejector, the design model and corresponding analysis were presented, and the relation of design parameters and the performance was partly revealed. The results revealed the confliction of two performance objectives and the complexity of the design problem. To clarify the entangled relation of design parameters and objectives and to afford facilities for the design process, the Pareto front(PF) concept was introduced and an MOEA/D algorithm was programmed to calculate the PFs of specific supersonic-supersonic ejector multi-objective optimization problems. The methodology adopted here proved to be effective and efficient for the supersonic-supersonic ejector design problem.

  9. 1999 Flight Mechanics Symposium

    Science.gov (United States)

    Lynch, John P. (Editor)

    1999-01-01

    This conference publication includes papers and abstracts presented at the Flight Mechanics Symposium held on May 18-20, 1999. Sponsored by the Guidance, Navigation and Control Center of Goddard Space Flight Center, this symposium featured technical papers on a wide range of issues related to orbit-attitude prediction, determination, and control; attitude sensor calibration; attitude determination error analysis; attitude dynamics; and orbit decay and maneuver strategy. Government, industry, and the academic community participated in the preparation and presentation of these papers.

  10. Adaptive structures flight experiments

    Science.gov (United States)

    Martin, Maurice

    The topics are presented in viewgraph form and include the following: adaptive structures flight experiments; enhanced resolution using active vibration suppression; Advanced Controls Technology Experiment (ACTEX); ACTEX program status; ACTEX-2; ACTEX-2 program status; modular control patch; STRV-1b Cryocooler Vibration Suppression Experiment; STRV-1b program status; Precision Optical Bench Experiment (PROBE); Clementine Spacecraft Configuration; TECHSAT all-composite spacecraft; Inexpensive Structures and Materials Flight Experiment (INFLEX); and INFLEX program status.

  11. Climate impact of supersonic air traffic: an approach to optimize a potential future supersonic fleet - results from the EU-project SCENIC

    Science.gov (United States)

    Grewe, V.; Stenke, A.; Ponater, M.; Sausen, R.; Pitari, G.; Iachetti, D.; Rogers, H.; Dessens, O.; Pyle, J.; Isaksen, I. S. A.; Gulstad, L.; Søvde, O. A.; Marizy, C.; Pascuillo, E.

    2007-10-01

    The demand for intercontinental transportation is increasing and people are requesting short travel times, which supersonic air transportation would enable. However, besides noise and sonic boom issues, which we are not referring to in this investigation, emissions from supersonic aircraft are known to alter the atmospheric composition, in particular the ozone layer, and hence affect climate significantly more than subsonic aircraft. Here, we suggest a metric to quantitatively assess different options for supersonic transport with regard to the potential destruction of the ozone layer and climate impacts. Options for fleet size, engine technology (nitrogen oxide emission level), cruising speed, range, and cruising altitude, are analyzed, based on SCENIC emission scenarios for 2050, which underlay the requirements to be as realistic as possible in terms of e.g., economic markets and profitable market penetration. This methodology is based on a number of atmosphere-chemistry and climate models to reduce model dependencies. The model results differ significantly in terms of the response to a replacement of subsonic aircraft by supersonic aircraft, e.g., concerning the ozone impact. However, model differences are smaller when comparing the different options for a supersonic fleet. Those uncertainties were taken into account to make sure that our findings are robust. The base case scenario, where supersonic aircraft get in service in 2015, a first fleet fully operational in 2025 and a second in 2050, leads in our simulations to a near surface temperature increase in 2050 of around 7 mK and with constant emissions afterwards to around 21 mK in 2100. The related total radiative forcing amounts to 22 mWm2 in 2050, with an uncertainty between 9 and 29 mWm2. A reduced supersonic cruise altitude or speed (from Mach 2 to Mach 1.6) reduces both, climate impact and ozone destruction, by around 40%. An increase in the range of the supersonic aircraft leads to more emissions at

  12. Magnesium and Space Flight.

    Science.gov (United States)

    Smith, Scott M; Zwart, Sara R

    2015-12-08

    Magnesium is an essential nutrient for muscle, cardiovascular, and bone health on Earth, and during space flight. We sought to evaluate magnesium status in 43 astronauts (34 male, 9 female; 47 ± 5 years old, mean ± SD) before, during, and after 4-6-month space missions. We also studied individuals participating in a ground analog of space flight (head-down-tilt bed rest; n = 27 (17 male, 10 female), 35 ± 7 years old). We evaluated serum concentration and 24-h urinary excretion of magnesium, along with estimates of tissue magnesium status from sublingual cells. Serum magnesium increased late in flight, while urinary magnesium excretion was higher over the course of 180-day space missions. Urinary magnesium increased during flight but decreased significantly at landing. Neither serum nor urinary magnesium changed during bed rest. For flight and bed rest, significant correlations existed between the area under the curve of serum and urinary magnesium and the change in total body bone mineral content. Tissue magnesium concentration was unchanged after flight and bed rest. Increased excretion of magnesium is likely partially from bone and partially from diet, but importantly, it does not come at the expense of muscle tissue stores. While further study is needed to better understand the implications of these findings for longer space exploration missions, magnesium homeostasis and tissue status seem well maintained during 4-6-month space missions.

  13. Interprofessional Flight Camp.

    Science.gov (United States)

    Alfes, Celeste M; Rowe, Amanda S

    2016-01-01

    The Dorothy Ebersbach Academic Center for Flight Nursing in Cleveland, OH, holds an annual flight camp designed for master's degree nursing students in the acute care nurse practitioner program, subspecializing in flight nursing at the Frances Payne Bolton School of Nursing at Case Western Reserve University. The weeklong interprofessional training is also open to any health care provider working in an acute care setting and focuses on critical care updates, trauma, and emergency care within the critical care transport environment. This year, 29 graduate nursing students enrolled in a master's degree program from Puerto Rico attended. Although the emergency department in Puerto Rico sees and cares for trauma patients, there is no formal trauma training program. Furthermore, the country only has 1 rotor wing air medical transport service located at the Puerto Rico Medical Center in San Juan. Flight faculty and graduate teaching assistants spent approximately 9 months planning for their participation in our 13th annual flight camp. Students from Puerto Rico were extremely pleased with the learning experiences at camp and expressed particular interest in having more training time within the helicopter flight simulator.

  14. Designing Flight Deck Procedures

    Science.gov (United States)

    Degani, Asaf; Wiener, Earl

    2005-01-01

    Three reports address the design of flight-deck procedures and various aspects of human interaction with cockpit systems that have direct impact on flight safety. One report, On the Typography of Flight- Deck Documentation, discusses basic research about typography and the kind of information needed by designers of flight deck documentation. Flight crews reading poorly designed documentation may easily overlook a crucial item on the checklist. The report surveys and summarizes the available literature regarding the design and typographical aspects of printed material. It focuses on typographical factors such as proper typefaces, character height, use of lower- and upper-case characters, line length, and spacing. Graphical aspects such as layout, color coding, fonts, and character contrast are discussed; and several cockpit conditions such as lighting levels and glare are addressed, as well as usage factors such as angular alignment, paper quality, and colors. Most of the insights and recommendations discussed in this report are transferable to paperless cockpit systems of the future and computer-based procedure displays (e.g., "electronic flight bag") in aerospace systems and similar systems that are used in other industries such as medical, nuclear systems, maritime operations, and military systems.

  15. Biomechanics and biomimetics in insect-inspired flight systems.

    Science.gov (United States)

    Liu, Hao; Ravi, Sridhar; Kolomenskiy, Dmitry; Tanaka, Hiroto

    2016-09-26

    Insect- and bird-size drones-micro air vehicles (MAV) that can perform autonomous flight in natural and man-made environments are now an active and well-integrated research area. MAVs normally operate at a low speed in a Reynolds number regime of 10(4)-10(5) or lower, in which most flying animals of insects, birds and bats fly, and encounter unconventional challenges in generating sufficient aerodynamic forces to stay airborne and in controlling flight autonomy to achieve complex manoeuvres. Flying insects that power and control flight by flapping wings are capable of sophisticated aerodynamic force production and precise, agile manoeuvring, through an integrated system consisting of wings to generate aerodynamic force, muscles to move the wings and a control system to modulate power output from the muscles. In this article, we give a selective review on the state of the art of biomechanics in bioinspired flight systems in terms of flapping and flexible wing aerodynamics, flight dynamics and stability, passive and active mechanisms in stabilization and control, as well as flapping flight in unsteady environments. We further highlight recent advances in biomimetics of flapping-wing MAVs with a specific focus on insect-inspired wing design and fabrication, as well as sensing systems.This article is part of the themed issue 'Moving in a moving medium: new perspectives on flight'.

  16. Equilibrium yield curves under regime switching

    OpenAIRE

    García-Verdú, Santiago

    2010-01-01

    This paper studies how inflation as a macroeconomic indicator affects nominal bond prices. I consider an economy with a representative agent with Epstein- Zin preferences. Regime switching affects the state-space capturing inflation and consumption growth. Thus, the agent is concerned about the intertemporal distribution of risk, which is affected by the persistence of the variables and the regimes. Regime switching allows for structural changes in the volatility of unexpected shocks. To the ...

  17. Numerical Investigation on Hydrogen-Fueled Scramjet Combustor with Parallel Strut Fuel Injector at a Flight Mach Number of 6

    Directory of Open Access Journals (Sweden)

    Krishna Pandey

    2016-01-01

    Full Text Available A numerical analysis of the inlet-combustor interaction and flow structure through a scramjet engine at a flight Mach number M = 6 with parallel injection (Strut with circular inlet is presented in the present research article. Three different angles of attack (α=-4°, α=0°, α=4° have been studied for parallel injection. The scramjet configuration used here is a modified version of DLR scramjet model. Fuel is injected at supersonic speed (M=2 through a parallel strut injector. For parallel injection, the shape of the strut is chosen in a way to produce strong stream wise vorticity and thus to enhance the hydrogen/air mixing inside the combustor. These numerical simulations are aimed to study the flow structure, supersonic mixing, and combustion phenomena for the three different types of geometries along with circular shaped strut configuration.

  18. Thermal regime of Negotinska Krajina

    Directory of Open Access Journals (Sweden)

    Živković Ljiljana

    2005-01-01

    Full Text Available Negotin Krajina geographically belongs to Mezian tablet that means it is widely open to the influences from the East but main air influences come from the West and North-West causes specific thermal characteristics. Meteorological station "Negotin" is the only one respectable station in the Krajina then we analyze results from various periods since 1901. It is important to emphasize that station "Negotin" doesn't have work continuity since the beginning of the century, thus for analyzing certain climate elements we have had to use method of analogy with station "Zaječar". A part of that, observations were not done by the same methodology so there is lack of some important indicators for this first period. To determine air thermo-regime of Negotin Krajina during 20 century, standard periods (1901-1930., 1931-1960. and 1961-1990 for analyzing climate elements suggested by WMO, were compared. Also, periods from 1925. to 1940. and from 1990. to 2000. were added to this analysis (according to data we had.

  19. Supersonic Plasma Spray Deposition of CoNiCrAlY Coatings on Ti-6Al-4V Alloy

    Science.gov (United States)

    Caliari, F. R.; Miranda, F. S.; Reis, D. A. P.; Essiptchouk, A. M.; Filho, G. P.

    2017-06-01

    Plasma spray is a versatile technology used for production of environmental and thermal barrier coatings, mainly in the aerospace, gas turbine, and automotive industries, with potential application in the renewable energy industry. New plasma spray technologies have been developed recently to produce high-quality coatings as an alternative to the costly low-pressure plasma-spray process. In this work, we studied the properties of as-sprayed CoNiCrAlY coatings deposited on Ti-6Al-4V substrate with smooth surface ( R a = 0.8 μm) by means of a plasma torch operating in supersonic regime at atmospheric pressure. The CoNiCrAlY coatings were evaluated in terms of their surface roughness, microstructure, instrumented indentation, and phase content. Static and dynamic depositions were investigated to examine their effect on coating characteristics. Results show that the substrate surface velocity has a major influence on the coating properties. The sprayed CoNiCrAlY coatings exhibit low roughness ( R a of 5.7 μm), low porosity (0.8%), excellent mechanical properties ( H it = 6.1 GPa, E it = 155 GPa), and elevated interface toughness (2.4 MPa m1/2).

  20. Evaluating and optimizing horticultural regimes in space plant growth facilities

    Science.gov (United States)

    Berkovich, Y. A.; Chetirkin, P. V.; Wheeler, R. M.; Sager, J. C.

    2004-01-01

    In designing innovative space plant growth facilities (SPGF) for long duration space flight, various limitations must be addressed including onboard resources: volume, energy consumption, heat transfer and crew labor expenditure. The required accuracy in evaluating onboard resources by using the equivalent mass methodology and applying it to the design of such facilities is not precise. This is due to the uncertainty of the structure and not completely understanding the properties of all associated hardware, including the technology in these systems. We present a simple criteria of optimization for horticultural regimes in SPGF: Qmax = max [ M · (EBI) 2/( V · E · T) ], where M is the crop harvest in terms of total dry biomass in the plant growth system; EBI is the edible biomass index (harvest index), V is volume occupied by the crop; E is the crop light energy supply during growth; T is the crop growth duration. The criterion reflects directly on the consumption of onboard resources for crop production.

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

    Science.gov (United States)

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

    2016-05-01

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

  2. Comparing Numerical Methods for Isothermal Magnetized Supersonic Turbulence

    Science.gov (United States)

    Kritsuk, Alexei G.; Nordlund, Åke; Collins, David; Padoan, Paolo; Norman, Michael L.; Abel, Tom; Banerjee, Robi; Federrath, Christoph; Flock, Mario; Lee, Dongwook; Li, Pak Shing; Müller, Wolf-Christian; Teyssier, Romain; Ustyugov, Sergey D.; Vogel, Christian; Xu, Hao

    2011-08-01

    Many astrophysical applications involve magnetized turbulent flows with shock waves. Ab initio star formation simulations require a robust representation of supersonic turbulence in molecular clouds on a wide range of scales imposing stringent demands on the quality of numerical algorithms. We employ simulations of supersonic super-Alfvénic turbulence decay as a benchmark test problem to assess and compare the performance of nine popular astrophysical MHD methods actively used to model star formation. The set of nine codes includes: ENZO, FLASH, KT-MHD, LL-MHD, PLUTO, PPML, RAMSES, STAGGER, and ZEUS. These applications employ a variety of numerical approaches, including both split and unsplit, finite difference and finite volume, divergence preserving and divergence cleaning, a variety of Riemann solvers, and a range of spatial reconstruction and time integration techniques. We present a comprehensive set of statistical measures designed to quantify the effects of numerical dissipation in these MHD solvers. We compare power spectra for basic fields to determine the effective spectral bandwidth of the methods and rank them based on their relative effective Reynolds numbers. We also compare numerical dissipation for solenoidal and dilatational velocity components to check for possible impacts of the numerics on small-scale density statistics. Finally, we discuss the convergence of various characteristics for the turbulence decay test and the impact of various components of numerical schemes on the accuracy of solutions. The nine codes gave qualitatively the same results, implying that they are all performing reasonably well and are useful for scientific applications. We show that the best performing codes employ a consistently high order of accuracy for spatial reconstruction of the evolved fields, transverse gradient interpolation, conservation law update step, and Lorentz force computation. The best results are achieved with divergence-free evolution of the

  3. Capital Flight and Economic Performance

    OpenAIRE

    Beja, Edsel Jr.

    2007-01-01

    Capital flight aggravates resource constraints and contributes to undermine long-term economic growth. Counterfactual calculations on the Philippines suggest that capital flight contributed to lower the quality of long-term economic growth. Sustained capital flight over three decades means that capital flight had a role for the Philippines to lose the opportunities to achieve economic takeoff. Unless decisive policy actions are taken up to address enduring capital flight and manage the macroe...

  4. Recent estimates of capital flight

    OpenAIRE

    Claessens, Stijn; Naude, David

    1993-01-01

    Researchers and policymakers have in recent years paid considerable attention to the phenomenon of capital flight. Researchers have focused on four questions: What concept should be used to measure capital flight? What figure for capital flight will emerge, using this measure? Can the occurrence and magnitude of capital flight be explained by certain (economic) variables? What policy changes can be useful to reverse capital flight? The authors focus strictly on presenting estimates of capital...

  5. Long duration flights management

    Science.gov (United States)

    Sosa-Sesma, Sergio; Letrenne, Gérard; Spel, Martin; Charbonnier, Jean-Marc

    Long duration flights (LDF) require a special management to take the best decisions in terms of ballast consumption and instant of separation. As a contrast to short duration flights, where meteorological conditions are relatively well known, for LDF we need to include the meteorological model accuracy in trajectory simulations. Dispersions on the fields of model (wind, temperature and IR fluxes) could make the mission incompatible with safety rules, authorized zones and others flight requirements. Last CNES developments for LDF act on three main axes: 1. Although ECMWF-NCEP forecast allows generating simulations from a 4D point (altitude, latitude, longitude and UT time), result is not statistical, it is determinist. To take into account model dispersion a meteorological NCEP data base was analyzed. A comparison between Analysis (AN) and Forecast (FC) for the same time frame had been done. Result obtained from this work allows implementing wind and temperature dispersions on balloon flight simulator. 2. For IR fluxes, NCEP does not provide ascending IR fluxes in AN mode but only in FC mode. To obtain the IR fluxes for each time frame, satellite images are used. A comparison between FC and satellites measurements had been done. Results obtained from this work allow implementing flux dispersions on balloon flight simulator. 3. An improved cartography containing a vast data base had been included in balloon flight simulator. Mixing these three points with balloon flight dynamics we have obtained two new tools for observing balloon evolution and risk, one of them is called ASTERISK (Statistic Tool for Evaluation of Risk) for calculations and the other one is called OBERISK (Observing Balloon Evolution and Risk) for visualization. Depending on the balloon type (super pressure, zero pressure or MIR) relevant information for the flight manager is different. The goal is to take the best decision according to the global situation to obtain the largest flight duration with

  6. Eclipse takeoff and flight

    Science.gov (United States)

    1998-01-01

    This 25-second clip shows the QF-106 'Delta Dart' tethered to the USAF C-141A during takeoff and in flight. NASA Dryden Flight Research Center, Edwards, California, supported a Kelly Space and Technology, Inc. (KST)/U.S. Air Force project known as Eclipse, which demonstrated a reusable tow launch vehicle concept. The purpose of the project was to demonstrate a reusable tow launch vehicle concept that had been conceived and patented by KST. Kelly Space obtained a contract with the USAF Research Laboratory for the tow launch demonstration project under the Small Business Innovation Research (SBIR) program. The USAF SBIR contract included the modifications to turn the QF-106 into the Experimental Demonstrator #1 (EXD-01), and the C141A aircraft to incorporate the tow provisions to link the two aircraft, as well as conducting flight tests. The demonstration consisted of ground and flight tests. These tests included a Combined Systems Test of both airplanes joined by a tow rope, a towed taxi test, and six towed flights. The primary goal of the project was demonstrating the tow phase of the Eclipse concept using a scaled-down tow aircraft (C-141A) and a representative aerodynamically-shaped aircraft (QF-106A) as a launch vehicle. This was successfully accomplished. On December 20, 1997, NASA research pilot Mark Stucky flew a QF-106 on the first towed flight behind an Air Force C-141 in the joint Eclipse project with KST to demonstrate the reusable tow launch vehicle concept developed by KST. Kelly hoped to use the data from the tow tests to validate a tow-to-launch procedure for reusable space launch vehicles. Stucky flew six successful tow tests between December 1997 and February 6, 1998. On February 6, 1998, the sixth and final towed flight brought the project to a successful completion. Preliminary flight results determined that the handling qualities of the QF-106 on tow were very stable; actual flight measured values of tow rope tension were well within predictions

  7. 14 CFR 121.493 - Flight time limitations: Flight engineers and flight navigators.

    Science.gov (United States)

    2010-01-01

    ... 14 Aeronautics and Space 3 2010-01-01 2010-01-01 false Flight time limitations: Flight engineers and flight navigators. 121.493 Section 121.493 Aeronautics and Space FEDERAL AVIATION ADMINISTRATION... AND OPERATIONS OPERATING REQUIREMENTS: DOMESTIC, FLAG, AND SUPPLEMENTAL OPERATIONS Flight...

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

    Science.gov (United States)

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

    2014-07-01

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

  9. DAST in Flight just after Structural Failure of Right Wing

    Science.gov (United States)

    1980-01-01

    Two BQM-34 Firebee II drones were modified with supercritical airfoils, called the Aeroelastic Research Wing (ARW), for the Drones for Aerodynamic and Structural Testing (DAST) program, which ran from 1977 to 1983. This photo, taken 12 June 1980, shows the DAST-1 (Serial #72-1557) immediately after it lost its right wing after suffering severe wing flutter. The vehicle crashed near Cuddeback Dry Lake. The Firebee II was selected for the DAST program because its standard wing could be removed and replaced by a supercritical wing. The project's digital flutter suppression system was intended to allow lighter wing structures, which would translate into better fuel economy for airliners. Because the DAST vehicles were flown intentionally at speeds and altitudes that would cause flutter, the program anticipated that crashes might occur. These are the image contact sheets for each image resolution of the NASA Dryden Drones for Aerodynamic and Structural Testing (DAST) Photo Gallery. From 1977 to 1983, the Dryden Flight Research Center, Edwards, California, (under two different names) conducted the DAST Program as a high-risk flight experiment using a ground-controlled, pilotless aircraft. Described by NASA engineers as a 'wind tunnel in the sky,' the DAST was a specially modified Teledyne-Ryan BQM-34E/F Firebee II supersonic target drone that was flown to validate theoretical predictions under actual flight conditions in a joint project with the Langley Research Center, Hampton, Virginia. The DAST Program merged advances in electronic remote control systems with advances in airplane design. Drones (remotely controlled, missile-like vehicles initially developed to serve as gunnery targets) had been deployed successfully during the Vietnamese conflict as reconnaissance aircraft. After the war, the energy crisis of the 1970s led NASA to seek new ways to cut fuel use and improve airplane efficiency. The DAST Program's drones provided an economical, fuel-conscious method for

  10. Crustal stress regime in Italy

    Directory of Open Access Journals (Sweden)

    M. Cesaro

    1997-06-01

    Full Text Available In order to obtain a reliable map of the present-day stress field in Italy, needed to better understand the active tectonic processes and to contribute to the assessment of seismic hazard, in 1992 we started to collect and analyze new data from borehole breakouts in deep oil and geothermal wells and focal mechanisms of earthquakes (2.5 < M <5 occurred in Italy between 1988 and 1995. From about 200 deep wells and 300 focal mechanisms analyzed to date, we infer that: the internal (SW sector of the Northern Apenninic arc is extending with minimum compressional stress (Shmin oriented ? ENE, while the external front is thrusting over the Adriatic foreland (Shmin ? NW-SE. The entire Southern Apennine is extending in NE direction (from the Tyrrhenian margin to the Apulian foreland and compression (in the foredeep is no longer active at the outer (NE thrust front. Between these two arcs, an abrupt change in the tectonic regime is detected with directions of horizontal stress changing by as much as 90º in the external front, around latitude 430N. Along the Ionian side of the Calabrian arc the stress directions inferred from breakouts and focal mechanisms are scattered with a hint of rotation from N-S Shmin close to the Southern Apennines, to ~ E-W directions in the Messina Strait. In Sicily, a NW-SE direction of SHmax is evident in the Hyblean foreland, parallel to the direction of plate motion between Africa and Europe. A more complex pattern of stress directions is observed in the thrust belt zone, with rotations from the regional trend (NW í directed SHmax to NE oriented SHmax. A predominant NW direction of SHmax is also detected in mainland Sicily from earthquake focal mechanisms, but no well data are available in this region. In the northern part of Sicily (Aeolian Islands a ~N-S direction of SHmax is observed.

  11. Framing of regimes and transition strategies

    DEFF Research Database (Denmark)

    Jensen, Jens Stissing

    2012-01-01

    This article suggests that transition strategies are always formulated in the context of specific representations of the regime and the challenges it faces. It is argued that the framing of a regime affects the envisioning of transition strategies. An analysis of the current development agenda...

  12. Multiscale regime shifts and planetary boundaries

    NARCIS (Netherlands)

    Hughes, T.P.; Carpenter, S.; Rockstrom, J.; Scheffer, M.; Walker, B.

    2013-01-01

    Life on Earth has repeatedly displayed abrupt and massive changes in the past, and there is no reason to expect that comparable planetary-scale regime shifts will not continue in the future. Different lines of evidence indicate that regime shifts occur when the climate or biosphere transgresses a ti

  13. LEGAL MATRIMONIAL REGIME IN B&H

    Directory of Open Access Journals (Sweden)

    Boris Krešić

    2011-12-01

    Full Text Available Matrimonial regime between spouses or between extramarital partners, and between parents and children is regulated by the Family Law Act of Bosnia and Herzegovina Federation, hereinafter FLA B&HF (SG FBiH 35/05, 41/05, Family Law Act of the Republic of Srpska, hereinafter FLA RS (SG RS”54/02, 41/08 and the Family Law Act of Brčko District, hereinafter FLA BD (SG RS, 66/07. Legal rules used for the regulation of the matrimonial regime between spouses, as well as between spouses and third parties make matrimonial regime (Ponjavić, 2005, p. 361. Matrimonial regime between spouses in family legislation in Bosnia and Herzegovina (B&H is regulated in two following ways: as legal matrimonial regime and as contract matrimonial regime. Legal regime is the one which applies on spouses if not arranged otherwise prior to contracting marriage or during marriage. In this paper the author indicates the differences between the legal matrimonial regimes of the two entities as well as those between the entities and Brčko District of Bosnia and Herzegovina.

  14. LOW DOSE MAGNESIUM SULPHATE REGIME FOR ECLAMPSIA

    Directory of Open Access Journals (Sweden)

    Bangal V

    2009-09-01

    Full Text Available Pre- eclampsia is one of the commonest medical complications seen during pregnancy. It contributes significantly to maternal and perinatal morbidity and mortality. Dr.J.A.Pritchard in 1955, introduced magnesium sulphate for control of convulsions in eclampsia and is used worldwide. Considering the low body mass index of indian women, a low dose magnesium sulphate regime has been introduced by some authors. Present study was carried out at tertiary care centre in rural area. Fifty cases of eclampsia were randomly selected to find out the efficacy of low dose magnesium sulphate regime to control eclamptic convulsions. Maternal and perinatal outcome and magnesium toxicity were analyzed. It was observed that 86% cases responded to initial intravenous dose of 4 grams of 20% magnesium sulphate . Eight percent cases, who got recurrence of convulsion, were controlled by additional 2 grams of 20% magnesium sulphate. Six percent cases required shifting to standard Pritchard regime, as they did not respond to low dose magnesium sulphate regime. The average total dose of magnesium sulphate required for control of convulsions was 20 grams ie. 54.4% less than that of standard Pritchard regime. The maternal and perinatal morbidity and mortality in the present study werecomparable to those of standard Pritchard regime. The study did not find a single case of magnesium related toxicity with low dose magnesium sulphate regime. Low dose magnesium sulphate regime was found to be safe and effective in eclampsia.

  15. Flight calls and orientation

    DEFF Research Database (Denmark)

    Larsen, Ole Næsbye; Andersen, Bent Bach; Kropp, Wibke

    2008-01-01

    flight calls was simulated by sequential computer controlled activation of five loudspeakers placed in a linear array perpendicular to the bird's migration course. The bird responded to this stimulation by changing its migratory course in the direction of that of the ‘flying conspecifics' but after about......  In a pilot experiment a European Robin, Erithacus rubecula, expressing migratory restlessness with a stable orientation, was video filmed in the dark with an infrared camera and its directional migratory activity was recorded. The flight overhead of migrating conspecifics uttering nocturnal...... 30 minutes it drifted back to its original migration course. The results suggest that songbirds migrating alone at night can use the flight calls from conspecifics as additional cues for orientation and that they may compare this information with other cues to decide what course to keep....

  16. Flight calls and orientation

    DEFF Research Database (Denmark)

    Larsen, Ole Næsbye; Andersen, Bent Bach; Kropp, Wibke

    2008-01-01

      In a pilot experiment a European Robin, Erithacus rubecula, expressing migratory restlessness with a stable orientation, was video filmed in the dark with an infrared camera and its directional migratory activity was recorded. The flight overhead of migrating conspecifics uttering nocturnal...... flight calls was simulated by sequential computer controlled activation of five loudspeakers placed in a linear array perpendicular to the bird's migration course. The bird responded to this stimulation by changing its migratory course in the direction of that of the ‘flying conspecifics' but after about...... 30 minutes it drifted back to its original migration course. The results suggest that songbirds migrating alone at night can use the flight calls from conspecifics as additional cues for orientation and that they may compare this information with other cues to decide what course to keep....

  17. Flight Dynamics Laboratory overview

    Science.gov (United States)

    Sandford, Thaddeus

    1986-01-01

    The Flight Dynamics Laboratory (FDL) is one of four Air Force Wright Aeronautical Laboratories (AFWAL) and part of the Aeronautical Systems Division located at Wright-Patterson AFB, Ohio. The FDL is responsible for the planning and execution of research and development programs in the areas of structures and dynamics, flight controls, vehicle equipment/subsystems, and aeromechanics. Some of the areas being researched in the four FDL divisions are as follows: large space structures (LSS) materials and controls; advanced cockpit designs; bird-strike-tolerant windshields; and hypersonic interceptor system studies. Two of the FDL divisions are actively involved in programs that deal directly with LSS control/structures interaction: the Flight Controls Division and the Structures and Dynamics Division.

  18. Experimental observations of a complex, supersonic nozzle concept

    Science.gov (United States)

    Magstadt, Andrew; Berry, Matthew; Glauser, Mark; Ruscher, Christopher; Gogineni, Sivaram; Kiel, Barry; Skytop Turbulence Labs, Syracuse University Team; Spectral Energies, LLC. Team; Air Force Research Laboratory Team

    2015-11-01

    A complex nozzle concept, which fuses multiple canonical flows together, has been experimentally investigated via pressure, schlieren and PIV in the anechoic chamber at Syracuse University. Motivated by future engine designs of high-performance aircraft, the rectangular, supersonic jet under investigation has a single plane of symmetry, an additional shear layer (referred to as a wall jet) and an aft deck representative of airframe integration. Operating near a Reynolds number of 3 ×106 , the nozzle architecture creates an intricate flow field comprised of high turbulence levels, shocks, shear & boundary layers, and powerful corner vortices. Current data suggest that the wall jet, which is an order of magnitude less energetic than the core, has significant control authority over the acoustic power through some non-linear process. As sound is a direct product of turbulence, experimental and analytical efforts further explore this interesting phenomenon associated with the turbulent flow. The authors acknowledge the funding source, a SBIR Phase II project with Spectral Energies, LLC. and AFRL turbine engine branch under the direction of Dr. Barry Kiel.

  19. Pulsed rotating supersonic source used with merged molecular beams

    CERN Document Server

    Sheffield, L; Krasovitskiy, V; Rathnayaka, K D D; Lyuksyutov, I F; Herschbach, D R

    2012-01-01

    We describe a pulsed rotating supersonic beam source, evolved from an ancestral device [M. Gupta and D. Herschbach, J. Phys. Chem. A 105, 1626 (2001)]. The beam emerges from a nozzle near the tip of a hollow rotor which can be spun at high-speed to shift the molecular velocity distribution downward or upward over a wide range. Here we consider mostly the slowing mode. Introducing a pulsed gas inlet system, cryocooling, and a shutter gate eliminated the main handicap of the original device, in which continuous gas flow imposed high background pressure. The new version provides intense pulses, of duration 0.1-0.6 ms (depending on rotor speed) and containing ~10^12 molecules at lab speeds as low as 35 m/s and ~ 10^15 molecules at 400 m/s. Beams of any molecule available as a gas can be slowed (or speeded); e.g., we have produced slow and fast beams of rare gases, O2, Cl2, NO2, NH3, and SF6. For collision experiments, the ability to scan the beam speed by merely adjusting the rotor is especially advantageous when...

  20. Turbulence characteristics in a supersonic cascade wake flow

    Energy Technology Data Exchange (ETDEWEB)

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

    1994-10-01

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

  1. LPWA using supersonic gas jet with tailored density profile

    Science.gov (United States)

    Kononenko, O.; Bohlen, S.; Dale, J.; D'Arcy, R.; Dinter, M.; Erbe, J. H.; Indorf, G.; di Lucchio, L.; Goldberg, L.; Gruse, J. N.; Karstensen, S.; Libov, V.; Ludwig, K.; Martinez de La Ossa, A.; Marutzky, F.; Niroula, A.; Osterhoff, J.; Quast, M.; Schaper, L.; Schwinkendorf, J.-P.; Streeter, M.; Tauscher, G.; Weichert, S.; Palmer, C.; Horbatiuk, Taras

    2016-10-01

    Laser driven plasma wakefield accelerators have been explored as a potential compact, reproducible source of relativistic electron bunches, utilising an electric field of many GV/m. Control over injection of electrons into the wakefield is of crucial importance in producing stable, mono-energetic electron bunches. Density tailoring of the target, to control the acceleration process, can also be used to improve the quality of the bunch. By using gas jets to provide tailored targets it is possible to provide good access for plasma diagnostics while also producing sharp density gradients for density down-ramp injection. OpenFOAM hydrodynamic simulations were used to investigate the possibility of producing tailored density targets in a supersonic gas jet. Particle-in-cell simulations of the resulting density profiles modelled the effect of the tailored density on the properties of the accelerated electron bunch. Here, we present the simulation results together with preliminary experimental measurements of electron and x-ray properties from LPWA experiments using gas jet targets and a 25 TW, 25 fs Ti:Sa laser system at DESY.

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

    Science.gov (United States)

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

    2017-04-01

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

  3. Effects of streamwise vortex breakdown on supersonic combustion.

    Science.gov (United States)

    Hiejima, Toshihiko

    2016-04-01

    This paper presents a numerical simulation study of the combustion structure of streamwise vortex breakdown at Mach number 2.48. Hydrogen fuel is injected into a combustor at sonic speed from the rear of a hypermixer strut that can generate streamwise vortices. The results show that the burning behavior is enhanced at the points of the shock waves that are incident on the vortex and therefore the vortex breakdown in the subsonic region occurs due to combustion. The breakdown domain in the mainstream is found to form a flame-holding region suited to combustion and to lead to a stable combustion field with detached flames. In this way, streamwise vortex breakdown has an essential role in combustion enhancement and the formation of flames that hold under supersonic inflow conditions. Finally, the combustion property defined here is shown to coincide with the produced-water mass flow. This property shows that the amount of combustion is saturated at equivalence ratios over 0.4, although there is a slight increase beyond 1.

  4. Damping insert materials for settling chambers of supersonic wind tunnels

    Science.gov (United States)

    Wu, Jie; Radespiel, Rolf

    2017-03-01

    This study describes the application of a novel damping insert material for reducing the flow fluctuations in a tandem nozzle supersonic wind tunnel. This new damping material is composed of multi-layer stainless steel wired meshes. The influences of the multi-layer mesh, such as the quantity of the mesh layer and the installed location in the settling chamber, to the freestream quality have been investigated. A Pitot probe instrumented with a Kulite pressure sensor and a hot-wire probe are employed to monitor the flow fluctuation in the test section of the wind tunnel. Thereafter, a combined modal analysis is applied for the disturbance qualification. Additionally, the transient Mach number in the test section is measured. The disturbance qualification indicates that the multi-layer mesh performs well in providing reduction of vorticity reduction and acoustic fluctuations. Comparable flow quality of the freestream was also obtained using a combination of flexible damping materials. However, the life-span of the new damping materials is much longer. The time transient of the Mach number measured in the test section indicates that the mean flow is rather constant over run time. Furthermore, the time-averaged pressure along the settling chamber is recorded and it shows the distribution of pressure drop by settling chamber inserts.

  5. Characteristics of Supersonic Closed Loop with Disk CCMHD Generator

    Science.gov (United States)

    Yamasaki, Hiroyuki; Murakami, Tomoyuki; Okuno, Yoshihiro

    Results of experimental study on performance of the supersonic closed loop with a disk MHD generator are described. The high temperature (> 1900K) argon circulation was carried out successfully during 2.4 hours. The heat gain and loss of argon was investigated, and a large heat loss was found at the diffuser and the exhausting duct although an energy efficiency of recuperator was high. The large heat loss was ascribed to water cooling at the diffuser and the exhausting duct. At the same time, the enhancement of heat transfer coefficient was suggested. The argon temperature and the heat loss calculated under an assumption of four times larger heat transfer coefficient have shown a good agreement with experimental ones. The pressure ratio inside the loop was discussed, and the result has indicated that the total pressure at the upstream of nozzle throat is decided by the total temperature and the mass flow. On the other hand, the total pressure at the downstream is determined by the total mass in the loop and the total pressure at the upstream. The first power generation was carried out, and a good correlation between the load resistance and the Hall voltage was observed. However, the power output remained very small.

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

    Institute of Scientific and Technical Information of China (English)

    Zhixiang Xiao; Song Fu

    2009-01-01

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

  7. Linear and Nonlinear Evolution of Disturbances in Supersonic Streamwise Vortices

    Science.gov (United States)

    Khorrami, Mehdi R.; Chang, Chau-Lyan; Wie, Yong-Sun

    1997-11-01

    Effective control of compressible streamwise vortices play a significant role in both external and internal aerodynamics. In this study, evolution of disturbances in a supersonic vortex is studied by using quasi-cylindrical linear stability analysis and parabolized stability equations (PSE)footnote M. R. Malik and C.-L. Chang, AIAA Paper 97-0758. formulation. Appropriate mean-flow profilesfootnote M. K. Smart, I. M. Kalkhoran, and J. Bentson, AIAA Paper 94-2576. suitable for stability analysis were identified and modeled successfully. Using linear stability analysis, the stability characteristics of axisymmetric vortices were mapped thoroughly. The results indicate that viscosity has very little effect while increasing Mach number significantly stabilizes the disturbance. Linear PSE analysis shows that the effect of streamwise mean flow variation is small for the case considered here. Nonlinear evolution of helical modes is also studied by using PSE. The growth of the disturbances results in the appearance of coherent large scale motion and significant mean flow distortion in the axial velocity and temperature fields. In the end, nonlinear effects tend to stabilize the vortex.

  8. Supersonic Propagation of Heat Waves in Low Density Heavy Material

    Institute of Scientific and Technical Information of China (English)

    Jiang Shaoen; Zhang Wenhai; Yi Rongqing; Cui Yanli; Chen Jiusen; Xu Yan; Ding Yongkun; Lai Dongxian; Zheng Zhijian; Huang Yikiang; Li Jinghong; Sun Kexu; Hu Xin

    2005-01-01

    The propagation of a supersonic heat-wave through copper-doped foam with a density of 50 mg/cm3 was experimentally investigated. The wave is driven by 140 eV Holhraum radiations generated in a cylindrical gold cavity heated by a 2 k J, 1ns laser pulse (0.35 μm). The delayed breakout time of the radiation waves from the rear side of the foam is measured by a threechromatic streaked x-ray spectrometer (TCS) consisting of a set of three-imaging pinholes and an array of three transmission gratings coupled with an x-ray streak camera (XSC). With one shot,simultaneous measurements of the delays of the drive source and the radiation with two different energies (210 eV, 840 eV) through the foam have been made for the first time. The experimental results indicate that the time delays vary with photon energies. The radiation with an energy of 210 eV propagates at a lower velocity. The radiating heat wave propagates with a velocity that is larger than the sound speed. Using TGS, the transmitting spectrum was measured, and then lower limit of the optical depth which is more than 1, was obtained. The experimental data were in agreement with numerical simulations.

  9. CFD-based Analysis of Aeroelastic behavior of Supersonic Fins

    Directory of Open Access Journals (Sweden)

    Tianxing Cai

    2011-02-01

    Full Text Available The main goal of this paper is to analyze the flutter boundary, transient loads of a supersonic fin, and the flutter with perturbation. Reduced order mode (ROM based on Volterra Series is presented to calculate the flutter boundary, and CFD/CSD coupling is used to compute the transient aerodynamic load. The Volterra-based ROM is obtained using the derivative of unsteady aerodynamic step-response, and the infinite plate spline is used to perform interpolation of physical quantities between the fluid and the structural grids. The results show that inertia force plays a significant role in the transient loads, the moment cause by inertia force is lager than the aerodynamic force, because of the huge transient loads, structure may be broken by aeroelasticity below the flutter dynamic pressure. Perturbations of aircraft affect the aeroelastic response evident, the reduction of flutter dynamic pressure by rolling perturbation form 15.4% to 18.6% when Mach from 2.0 to 3.0. It is necessary to analyze the aeroelasticity behaviors under the compositive force environment.

  10. 2001 Flight Mechanics Symposium

    Science.gov (United States)

    Lynch, John P. (Editor)

    2001-01-01

    This conference publication includes papers and abstracts presented at the Flight Mechanics Symposium held on June 19-21, 2001. Sponsored by the Guidance, Navigation and Control Center of Goddard Space Flight Center, this symposium featured technical papers on a wide range of issues related to attitude/orbit determination, prediction and control; attitude simulation; attitude sensor calibration; theoretical foundation of attitude computation; dynamics model improvements; autonomous navigation; constellation design and formation flying; estimation theory and computational techniques; Earth environment mission analysis and design; and, spacecraft re-entry mission design and operations.

  11. Technologies for hypersonic flight

    Science.gov (United States)

    Steinheil, Eckart; Uhse, Wolfgang

    An account is given of the technology readiness requirements of the West German Saenger II air-breathing first-stage, two-stage reusable launcher system. The present, five-year conceptual development phase will give attention to propulsion, aerothermodynamic, materials/structures, and flight guidance technology development requirements. The second, seven-year development phase will involve other West European design establishments and lead to the construction of a demonstration vehicle. Attention is presently given to the air-breathing propulsion system, and to flight-weight structural systems under consideration for both external heating and internal cryogenic tankage requirements.

  12. Effect of particle in-flight behavior on the composition of thermal barrier coatings

    Energy Technology Data Exchange (ETDEWEB)

    Zhao, L. [State Key Laboratory for Mechanical Behavior of Materials, Xi’an Jiaotong University, Xi’an 710049 (China); Bai, Y., E-mail: byxjtu@gmail.com [State Key Laboratory for Mechanical Behavior of Materials, Xi’an Jiaotong University, Xi’an 710049 (China); School of Mechanical Engineering, Xi’an Jiaotong University, Xi’an 710049 (China); Tang, J.J.; Liu, K. [State Key Laboratory for Mechanical Behavior of Materials, Xi’an Jiaotong University, Xi’an 710049 (China); Ding, C.H. [State Key Laboratory for Strength and Vibration of Mechanical Structures, Xi’an Jiaotong University, Xi’an 710049 (China); Yang, J.F. [State Key Laboratory for Mechanical Behavior of Materials, Xi’an Jiaotong University, Xi’an 710049 (China); Han, Z.H., E-mail: zhhan1955@163.com [State Key Laboratory for Mechanical Behavior of Materials, Xi’an Jiaotong University, Xi’an 710049 (China)

    2013-12-01

    In this work, 6 to 11 mol% YO{sub 1.5}-stabilized zirconia (YSZ) coatings were deposited by supersonic and conventional atmospheric plasma spraying. During spraying, the surface temperature and velocity of in-flight particles were monitored by Spray Watch 2i on-line system. The phase composition of as-sprayed coatings was analyzed by X-ray diffractometry (XRD). Lattice parameters, tetragonality and the content of YO{sub 1.5} (mol%) of as-sprayed coatings were calculated according to the position of (0 0 4) and (4 0 0) diffraction peaks. It was found that the as-sprayed coatings were composed of metastable non-transformable tetragonal phase (t′). However, the amount of YO{sub 1.5} (mol%) in the as-sprayed coatings decreased with the increase of melting index of in-flight particles due to the partial evaporation of YO{sub 1.5} during spraying.

  13. Human engineering analysis for the high speed civil transport flight deck

    Science.gov (United States)

    Regal, David M.; Alter, Keith W.

    1993-01-01

    The Boeing Company is investigating the feasibility of building a second generation supersonic transport. If current studies support its viability, this airplane, known as the High Speed Civil Transport (HSCT), could be launched early in the next century. The HSCT will cruise at Mach 2.4, be over 300 feet long, have an initial range of between 5000 and 6000 NM, and carry approximately 300 passengers. We are presently involved in developing an advanced flight deck for the HSCT. As part of this effort we are undertaking a human engineering analysis that involves a top-down, mission driven approach that will allow a systematic determination of flight deck functional and information requirements. The present paper describes this work.

  14. Advanced Concept Studies for Supersonic Commercial Transports Entering Service in the 2018-2020 Period Phase 2

    Science.gov (United States)

    Morgenstern, John; Buonanno, Michael; Yao, Jixian; Murugappan, Mugam; Paliath, Umesh; Cheung, Lawrence; Malcevic, Ivan; Ramakrishnan, Kishore; Pastouchenko, Nikolai; Wood, Trevor; Martens, Steve; Viars, Phil; Tersmette, Trevor; Lee, Jason; Simmons, Ron; Plybon, David; Alonso, Juan; Palacios, Francisco; Lukaczyk, Trent; Carrier, Gerald

    2015-01-01

    Lockheed Martin Aeronautics Company (LM), working in conjunction with General Electric Global Research (GE GR) and Stanford University, executed a 19 month program responsive to the NASA sponsored "N+2 Supersonic Validation: Advanced Concept Studies for Supersonic Commercial Transports Entering Service in the 2018-2020 Period" contract. The key technical objective of this effort was to validate integrated airframe and propulsion technologies and design methodologies necessary to realize a supersonic vehicle capable of meeting the N+2 environmental and performance goals. The N+2 program is aligned with NASA's Supersonic Project and is focused on providing system level solutions capable of overcoming the efficiency, environmental, and performance barriers to practical supersonic flight. The N+2 environmental and performance goals are outlined in the technical paper, AIAA-2014-2138 (Ref. 1) along with the validated N+2 Phase 2 results. Our Phase 2 efforts built upon our Phase 1 studies (Ref. 2) and successfully demonstrated the ability to design and test realistic configurations capable of shaped sonic booms over the width of the sonic boom carpet. Developing a shaped boom configuration capable of meeting the N+2 shaped boom targets is a key goal for the N+2 program. During the LM Phase 1 effort, LM successfully designed and tested a shaped boom trijet configuration (1021) capable of achieving 85 PLdB under track (forward and aft shock) and up to 28 deg off-track at Mach 1.6. In Phase 2 we developed a refined configuration (1044-2) that extended the under 85 PLdB sonic boom level over the entire carpet of 52 deg off-track at a cruise Mach number of 1.7. Further, the loudness level of the configuration throughout operational conditions calculates to an average of 79 PLdB. These calculations rely on propagation employing Burger's (sBOOM) rounding methodology, and there are indications that the configuration average loudness would actually be 75 PLdB. We also added

  15. SCAMP: Rapid Focused Sonic Boom Waypoint Flight Planning Methods, Execution, and Results

    Science.gov (United States)

    Haering, Edward A., Jr.; Cliatt, Larry J., II; Delaney, Michael M., Jr.; Plotkin, Kenneth J.; Maglieri, Domenic J.; Brown, Jacob C.

    2012-01-01

    Successful execution of the flight phase of the Superboom Caustic Analysis and Measurement Project (SCAMP) required accurate placement of focused sonic booms on an array of prepositioned ground sensors. While the array was spread over a 10,000-ft-long area, this is a relatively small region when considering the speed of a supersonic aircraft and sonic boom ray path variability due to shifting atmospheric conditions and aircraft trajectories. Another requirement of the project was to determine the proper position for a microphone-equipped motorized glider to intercept the sonic boom caustic, adding critical timing to the constraints. Variability in several inputs to these calculations caused some shifts of the focus away from the optimal location. Reports of the sonic booms heard by persons positioned amongst the array were used to shift the focus closer to the optimal location for subsequent passes. This paper describes the methods and computations used to place the focused sonic boom on the SCAMP array and gives recommendations for their accurate placement by future quiet supersonic aircraft. For the SCAMP flights, 67% of the foci were placed on the ground array with measured positions within a few thousand feet of computed positions. Among those foci with large caustic elevation angles, 96% of foci were placed on the array, and measured positions were within a few hundred feet of computed positions. The motorized glider captured sonic booms on 59% of the passes when the instrumentation was operating properly.

  16. A collinear tandem time-of-flight mass spectrometer for infrared photodissociation spectroscopy of mass-selected ions

    Institute of Scientific and Technical Information of China (English)

    WANG GuanJun; CHI ChaoXian; XING XiaoPeng; DING ChuanFan; ZHOU MingFei

    2014-01-01

    An apparatus based on collinear tandem time-of-flight mass spectrometer has been designed for the measurement of infrared photodissociation spectroscopy of mass-selected ions in the gas phase.The ions from a pulsed laser vaporization supersonic ion source are skimmed and mass separated by a Wiley-McLaren time-of-flight mass spectrometer.The ion of interest is mass selected,decelerated and dissociated by a tunable IR laser.The fragment and parent ions are reaccelerated and mass analyzed by the second time-of-flight mass spectrometer.A simple new assembly integrated with mass gate,deceleration and reacceleration ion optics was designed,which allows us to measure the infrared spectra of mass selected ions with high sensitivity and easy timing synchronization.

  17. Acoustic measurements of models of military style supersonic nozzle jets

    NARCIS (Netherlands)

    Kuo, C.W.; Veltin, J.; McLaughlin, D.K.

    2014-01-01

    Modern military aircraft jet engines are designed with variable-geometry nozzles to provide optimal thrust in different operating conditions, depending on the flight envelope. However, acoustic measurements for such nozzles are scarce, due to the cost involved in making full-scale measurements and

  18. Acoustic measurements of models of military style supersonic nozzle jets

    NARCIS (Netherlands)

    Kuo, C.W.; Veltin, J.; McLaughlin, D.K.

    2014-01-01

    Modern military aircraft jet engines are designed with variable-geometry nozzles to provide optimal thrust in different operating conditions, depending on the flight envelope. However, acoustic measurements for such nozzles are scarce, due to the cost involved in making full-scale measurements and t

  19. Biomechanics and biomimetics in insect-inspired flight systems

    Science.gov (United States)

    Liu, Hao; Ravi, Sridhar; Kolomenskiy, Dmitry; Tanaka, Hiroto

    2016-01-01

    Insect- and bird-size drones—micro air vehicles (MAV) that can perform autonomous flight in natural and man-made environments are now an active and well-integrated research area. MAVs normally operate at a low speed in a Reynolds number regime of 104–105 or lower, in which most flying animals of insects, birds and bats fly, and encounter unconventional challenges in generating sufficient aerodynamic forces to stay airborne and in controlling flight autonomy to achieve complex manoeuvres. Flying insects that power and control flight by flapping wings are capable of sophisticated aerodynamic force production and precise, agile manoeuvring, through an integrated system consisting of wings to generate aerodynamic force, muscles to move the wings and a control system to modulate power output from the muscles. In this article, we give a selective review on the state of the art of biomechanics in bioinspired flight systems in terms of flapping and flexible wing aerodynamics, flight dynamics and stability, passive and active mechanisms in stabilization and control, as well as flapping flight in unsteady environments. We further highlight recent advances in biomimetics of flapping-wing MAVs with a specific focus on insect-inspired wing design and fabrication, as well as sensing systems. This article is part of the themed issue ‘Moving in a moving medium: new perspectives on flight’. PMID:27528780

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

    Science.gov (United States)

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

    2014-02-01

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

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

    Institute of Scientific and Technical Information of China (English)

    2009-01-01

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

  2. Fundamental Aeronautics Program: Overview of Propulsion Work in the Supersonic Cruise Efficiency Technical Challenge

    Science.gov (United States)

    Castner, Ray

    2012-01-01

    The Supersonics Project, part of NASA's Fundamental Aeronautics Program, contains a number of technical challenge areas which include sonic boom community response, airport noise, high altitude emissions, cruise efficiency, light weight durable engines/airframes, and integrated multi-discipline system design. This presentation provides an overview of the current (2012) activities in the supersonic cruise efficiency technical challenge, and is focused specifically on propulsion technologies. The intent is to develop and validate high-performance supersonic inlet and nozzle technologies. Additional work is planned for design and analysis tools for highly-integrated low-noise, low-boom applications. If successful, the payoffs include improved technologies and tools for optimized propulsion systems, propulsion technologies for a minimized sonic boom signature, and a balanced approach to meeting efficiency and community noise goals. In this propulsion area, the work is divided into advanced supersonic inlet concepts, advanced supersonic nozzle concepts, low fidelity computational tool development, high fidelity computational tools, and improved sensors and measurement capability. The current work in each area is summarized.

  3. Fundamental Aeronautics Program: Overview of Project Work in Supersonic Cruise Efficiency

    Science.gov (United States)

    Castner, Raymond

    2011-01-01

    The Supersonics Project, part of NASA?s Fundamental Aeronautics Program, contains a number of technical challenge areas which include sonic boom community response, airport noise, high altitude emissions, cruise efficiency, light weight durable engines/airframes, and integrated multi-discipline system design. This presentation provides an overview of the current (2011) activities in the supersonic cruise efficiency technical challenge, and is focused specifically on propulsion technologies. The intent is to develop and validate high-performance supersonic inlet and nozzle technologies. Additional work is planned for design and analysis tools for highly-integrated low-noise, low-boom applications. If successful, the payoffs include improved technologies and tools for optimized propulsion systems, propulsion technologies for a minimized sonic boom signature, and a balanced approach to meeting efficiency and community noise goals. In this propulsion area, the work is divided into advanced supersonic inlet concepts, advanced supersonic nozzle concepts, low fidelity computational tool development, high fidelity computational tools, and improved sensors and measurement capability. The current work in each area is summarized.

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

    Institute of Scientific and Technical Information of China (English)

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

    2009-01-01

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

  5. Space Shuttle flight control system

    Science.gov (United States)

    Klinar, W. J.; Kubiak, E. T.; Peters, W. H.; Saldana, R. L.; Smith, E. E., Jr.; Stegall, H. W.

    1975-01-01

    The Space Shuttle is a control stabilized vehicle with control provided by an all digital, fly-by-wire flight control system. This paper gives a description of the several modes of flight control which correspond to the Shuttle mission phases. These modes are ascent flight control (including open loop first stage steering, the use of four computers operating in parallel and inertial guidance sensors), on-orbit flight control (with a discussion of reaction control, phase plane switching logic, jet selection logic, state estimator logic and OMS thrust vector control), entry flight control and TAEM (terminal area energy management to landing). Also discussed are redundancy management and backup flight control.

  6. A Proposed Ascent Abort Flight Test for the Max Launch Abort System

    Science.gov (United States)

    Tartabini, Paul V.; Gilbert, Michael G.; Starr, Brett R.

    2016-01-01

    The NASA Engineering and Safety Center initiated the Max Launch Abort System (MLAS) Project to investigate alternate crew escape system concepts that eliminate the conventional launch escape tower by integrating the escape system into an aerodynamic fairing that fully encapsulates the crew capsule and smoothly integrates with the launch vehicle. This paper proposes an ascent abort flight test for an all-propulsive towerless escape system concept that is actively controlled and sized to accommodate the Orion Crew Module. The goal of the flight test is to demonstrate a high dynamic pressure escape and to characterize jet interaction effects during operation of the attitude control thrusters at transonic and supersonic conditions. The flight-test vehicle is delivered to the required test conditions by a booster configuration selected to meet cost, manufacturability, and operability objectives. Data return is augmented through judicious design of the boost trajectory, which is optimized to obtain data at a range of relevant points, rather than just a single flight condition. Secondary flight objectives are included after the escape to obtain aerodynamic damping data for the crew module and to perform a high-altitude contingency deployment of the drogue parachutes. Both 3- and 6-degree-of-freedom trajectory simulation results are presented that establish concept feasibility, and a Monte Carlo uncertainty assessment is performed to provide confidence that test objectives can be met.

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

    Science.gov (United States)

    Sabri, Farhad

    circular cylindrical shell or truncated conical shell subjected to internal/external pressure and axial compression loading. This is a typical example of external liquid propellant tanks of space shuttles and re-entry vehicles where they may experience this kind of loading during the flight. In the current work, different end boundary conditions of a circular cylindrical shell with different filling ratios were analyzed. To the best author' knowledge this is the first study where this kind of complex loading and boundary conditions are treated together during such an analysis. Only static instability, divergence, was observed where it showed that the fluid filling ratio does not have any effect on the critical buckling pressure and axial compression. It only reduces the vibration frequencies. It also revealed that the pressurized shell loses its stability at a higher critical axial load. (ii) Aeroelastic analysis of empty or partially liquid filled circular cylindrical and conical shells. Different boundary conditions with different geometries of shells subjected to supersonic air flow are studied here. In all of cases shell loses its stability though the coupled mode flutter. The results showed that internal pressure has a stabilizing effect and increases the critical flutter speed. It is seen that the value of critical dynamic pressure changes rapidly and widely as the filling ratio increases from a low value. In addition, by increasing the length ratio the decrement of flutter speed is decreased and vanishes. This rapid change in critical dynamic pressure at low filling ratios and its almost steady behaviour at large filling ratios indicate that the fluid near the bottom of the shell is largely influenced by elastic deformation when a shell is subjected to external subsonic flow. Based on comparison with the existing numerical, analytical and experimental data and the power of capabilities of this hybrid finite element method to model different boundary conditions and

  8. Flight Mechanics Symposium 1997

    Science.gov (United States)

    Walls, Donna M. (Editor)

    1997-01-01

    This conference publication includes papers and abstracts presented at the Flight Mechanics Symposium. This symposium featured technical papers on a wide range of issues related to orbit-attitude prediction, determination, and control; attitude sensor calibration; attitude determination error analysis; attitude dynamics; and orbit decay and maneuver strategy. Government, industry, and the academic community participated in the preparation and presentation of these papers.

  9. Overbooking Airline Flights.

    Science.gov (United States)

    Austin, Joe Dan

    1982-01-01

    The problems involved in making reservations for airline flights is discussed in creating a mathematical model designed to maximize an airline's income. One issue not considered in the model is any public relations problem the airline may have. The model does take into account the issue of denied boarding compensation. (MP)

  10. Overbooking Airline Flights.

    Science.gov (United States)

    Austin, Joe Dan

    1982-01-01

    The problems involved in making reservations for airline flights is discussed in creating a mathematical model designed to maximize an airline's income. One issue not considered in the model is any public relations problem the airline may have. The model does take into account the issue of denied boarding compensation. (MP)

  11. OMV In Flight

    Science.gov (United States)

    1988-01-01

    In this 1988 artist's concept, the Orbital Maneuvering Vehicle (OMV), closes in on a satellite. As envisioned by Marshall Space Flight plarners, the OMV would be a remotely-controlled free-flying space tug which would place, rendezvous, dock, and retrieve orbital payloads.

  12. H-infinity based integrated flight-propulsion control design for a STOVL aircraft in transition flight

    Science.gov (United States)

    Garg, Sanjay; Mattern, Duane L.; Bright, Michelle M.; Ouzts, Peter J.

    1990-01-01

    Results are presented from an application of H-infinity control design methodology to a centralized integrated flight/propulsion control (IFPC) system design for a supersonic Short Take-Off and Vertical Landing (STOVL) fighter aircraft in transition flight. The overall design methodology consists of a centralized IFPC controller design with controller partitioning. Only the feedback controller design portion of the methodology is addressed. Design and evaluation vehicle models are summarized, and insight is provided into formulating the H-infinity control problem such that it reflects the IFPC design objectives. The H-infinity controller is shown to provide decoupled command tracking for the design model. The controller order could be significantly reduced by modal residualization of the fast controller modes without any deterioration in performance. A discussion is presented of the areas in which the controller performance needs to be improved, and ways in which these improvements can be achieved within the framework of an H-infinity based linear control design.

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

    Institute of Scientific and Technical Information of China (English)

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

    2008-01-01

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

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

    Science.gov (United States)

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

    2016-10-01

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

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

    Institute of Scientific and Technical Information of China (English)

    2008-01-01

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

  16. An experimental study of aero-optical aberration and dithering of supersonic mixing layer via BOS

    Institute of Scientific and Technical Information of China (English)

    2010-01-01

    The optical performance of supersonic mixing layer is heavily deteriorated by the aero-optical aberration and dithering of coherent structures, but current measuring methods limit the spatiotemporal resolution in relevant studies. A high resolution whole-field aero-optical aberration and dithering measuring method based on the Background Orient Schlieren (BOS) technique was studied. The systematic structure, sensitivity and resolution of BOS are analyzed in this paper. The aero-optical aberration and dithering of streamwise structures in supersonic mixing layers were quantificationally studied with BOS. The aberration field of spanwise structures revealed the ribbon-like aberration structures, which heavily restrict the optical performance of a mixing layer. The quantifications of aero-optical aberration and dithering are very important in studying aero-optical performance of supersonic mixing layer.

  17. Design and Testing of CO2 Compression Using Supersonic Shock Wave Technology

    Energy Technology Data Exchange (ETDEWEB)

    Koopman, Aaron [Seattle Technology Center, Bellevue, WA (United States)

    2015-06-01

    This report summarizes work performed by Ramgen and subcontractors in pursuit of the design and construction of a 10 MW supersonic CO2 compressor and supporting facility. The compressor will demonstrate application of Ramgen’s supersonic compression technology at an industrial scale using CO2 in a closed-loop. The report includes details of early feasibility studies, CFD validation and comparison to experimental data, static test experimental results, compressor and facility design and analyses, and development of aerodynamic tools. A summary of Ramgen's ISC Engine program activity is also included. This program will demonstrate the adaptation of Ramgen's supersonic compression and advanced vortex combustion technology to result in a highly efficient and cost effective alternative to traditional gas turbine engines. The build out of a 1.5 MW test facility to support the engine and associated subcomponent test program is summarized.

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

    Institute of Scientific and Technical Information of China (English)

    YANG Hui; LI Feng; SUN Baigang

    2012-01-01

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

  19. Navier—Stokes Computations of the Supersonic Ejector—Diffuser System with a Second Throat

    Institute of Scientific and Technical Information of China (English)

    Heuy-DongKim; ToshiakiSetoguchi; 等

    1999-01-01

    The supersonic ejector-diffuser system with a second throat was simulated using CFD.An explicit finite volume scheme was applied to solve two-dimensional Navier-Stokes equations with standard κ-εturbulence model.The vacuum performance of the supersonic ejector-diffuser system was investigated by changing the ejector throat area ration and the operating pressure ratio.Two convergent-divergent nozzles with design Mach number of 2.11 and 3.41 were selected to give the supersonic operation of the ejector-diffuser system.The presence of a second throat strongly affected the shock wave structure inside the mixing tube as well as the spreading of the under-expanded jet discharging from the primary nozzle.There were optimum values of the operating pressure ratio and ejector throat area ratio for the vacuum performance of the system to maximize.

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

    Institute of Scientific and Technical Information of China (English)

    Zeng-YuanGuo; Zhi-HongLiu

    1994-01-01

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

  1. High Efficiency Low Cost CO2 Compression Using Supersonic Shock Wave Technology

    Energy Technology Data Exchange (ETDEWEB)

    Williams, J; Aarnio, M; Grosvenor, A; Taylor, D; Bucher, J

    2010-12-31

    Development and testing results from a supersonic compressor are presented. The compressor achieved record pressure ratio for a fully-supersonic stage and successfully demonstrated the technology potential. Several tasks were performed in compliance with the DOE award objectives. A high-pressure ratio compressor was retrofitted to improve rotordynamics behavior and successfully tested. An outside review panel confirmed test results and design approach. A computational fluid dynamics code used to analyze the Ramgen supersonic flowpath was extensively and successfully modified to improve use on high-performance computing platforms. A comprehensive R&D implementation plan was developed and used to lay the groundwork for a future full-scale compressor demonstration. Conceptual design for a CO2 demonstration compressor was developed and reviewed.

  2. Reverse Circulation Drilling Method Based on a Supersonic Nozzle for Dust Control

    Directory of Open Access Journals (Sweden)

    Dongyu Wu

    2016-12-01

    Full Text Available To reduce dust generated from drilling processes, a reverse circulation drilling method based on a supersonic nozzle is proposed. The suction performance is evaluated by the entrainment ratio. A series of preliminary laboratory experiments based on orthogonal experimental design were conducted to test the suction performance and reveal the main factors. Computational fluid dynamics (CFD were conducted to thoroughly understand the interaction mechanism of the flows. The Schlieren technique was further carried out to reveal the flow characteristic of the nozzle. The results show that the supersonic nozzle can significantly improve the reverse circulation effect. A high entrainment ratio up to 0.76 was achieved, which implied strong suction performance. The CFD results agreed well with experimental data with a maximum difference of 17%. This work presents the great potential for supersonic nozzles and reverse circulation in dust control, which is significant to protect the envrionment and people’s health.

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

    Institute of Scientific and Technical Information of China (English)

    HeuydongKim; ToshiakiSetoguchi; 等

    1999-01-01

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

  4. Linear models for sound from supersonic reacting mixing layers

    Science.gov (United States)

    Chary, P. Shivakanth; Samanta, Arnab

    2016-12-01

    We perform a linearized reduced-order modeling of the aeroacoustic sound sources in supersonic reacting mixing layers to explore their sensitivities to some of the flow parameters in radiating sound. Specifically, we investigate the role of outer modes as the effective flow compressibility is raised, when some of these are expected to dominate over the traditional Kelvin-Helmholtz (K-H) -type central mode. Although the outer modes are known to be of lesser importance in the near-field mixing, how these radiate to the far-field is uncertain, on which we focus. On keeping the flow compressibility fixed, the outer modes are realized via biasing the respective mean densities of the fast (oxidizer) or slow (fuel) side. Here the mean flows are laminar solutions of two-dimensional compressible boundary layers with an imposed composite (turbulent) spreading rate, which we show to significantly alter the growth of instability waves by saturating them earlier, similar to in nonlinear calculations, achieved here via solving the linear parabolized stability equations. As the flow parameters are varied, instability of the slow modes is shown to be more sensitive to heat release, potentially exceeding equivalent central modes, as these modes yield relatively compact sound sources with lesser spreading of the mixing layer, when compared to the corresponding fast modes. In contrast, the radiated sound seems to be relatively unaffected when the mixture equivalence ratio is varied, except for a lean mixture which is shown to yield a pronounced effect on the slow mode radiation by reducing its modal growth.

  5. Laser Desorption Supersonic Jet Spectroscopy of Hydrated Tyrosine

    Science.gov (United States)

    Oba, Hikari; Shimozono, Yoko; Ishiuchi, Shun-Ichi; Fujii, Masaaki; Carcabal, Pierre

    2013-06-01

    The structure of tyrosine (tyr) consists of amino-acid chain and phenol, and it has roughly two possible binding sites for water, amino-acid site and phenolic OH site. Investigating how water molecule binds to tyr will give fundamental information for hydrations of peptide and protein. Resonance enhanced multi photon ionization (REMPI) spectrum of tyr-water 1:1 cluster has already been reported by de Vries and co-workers, however, no analysis on the hydrated structures has been reported. In the REMPI spectrum, two clusters of bands are observed; one appears at ˜35600 cm^{-1} energy region which is the almost same with 0-0 transitions of tyr monomer, and another is observed at ˜300 cm^{-1} lower than the former. Based on the electronic transition energy of phenylalanine and the hydrated clusters, the former is expected to be derived from a structure that water binds to amino acid site. On the other hand, it is plausibly predicted that the latter originates from a structure that water binds to phenolic OH group, because the electronic transition of mono hydrated phenol is ˜300 cm^{-1} red-shifted from the monomer. We applied IR dip spectroscopy which can measure conformer selective IR spectra to the tyr-(H_{2}O)_{1} clusters by using laser desorption supersonic jet technique to confirm the assignments. Especially in the phenolic OH bound isomer, it was found that the intra molecular hydrogen bond within amino-acid chain, which is far from the water molecule and cannot interact directly with each other, is strengthened by the hydration. A. Abio-Riziq et al., J. Phys. Chem. A, 115, 6077 (2011). Y. Shimozono, et al., Phys. Chem. Chem. Phys., (2013) DOI: 10.1039/c3cp43573c. T. Ebata et al., Phys. Chem. Chem. Phys., 8, 4783 (2006). T. Watanabe et al., J. Chem. Phys., 105, 408 (1996).

  6. Transonic Aerodynamic Characteristics of a Model of a Proposed Six-Engine Hull-Type Seaplane Designed for Supersonic Flight

    Science.gov (United States)

    Wornom, Dewey E.

    1960-01-01

    Force tests of a model of a proposed six-engine hull-type seaplane were performed in the Langley 8-foot transonic pressure tunnel. The results of these tests have indicated that the model had a subsonic zero-lift drag coefficient of 0.0240 with the highest zero-lift drag coefficient slightly greater than twice the subsonic drag level. Pitchup tendencies were noted for subsonic Mach numbers at relatively high lift coefficients. Wing leading-edge droop increased the maximum lift-drag ratio approximately 8 percent at a Mach number of 0.80 but this effect was negligible at a Mach number of 0.90 and above. The configuration exhibited stable lateral characteristics over the test Mach number range.

  7. Environmental Impact Analysis Process. Environmental Impact Statement. Supersonic Flight Operations in the Reserve Military Operations Area, Holloman AFB, New Mexico

    Science.gov (United States)

    1983-09-01

    information 36. Year Month dayt 19 Cc. Returned for c. State f ~~(Name and telephone number Ending amendment -0 e____date_19 = d Deferred d. Local M___ 0...retail sales...the assessed evaluation of taxed property has increased very 3 Istronglyu. In its summary of its findings in the 4 active MOAs, this. I...upon the information presented and isinformation presented, omitted or misstated in this environmental mpact statement. In many ways this impact

  8. Environmental Impact Analysis Process. Final Environmental Impact Statement. Supersonic Flight Operations in the Reserve Military Operations Area, Holloman, New Mexico

    Science.gov (United States)

    1983-01-01

    protest, whether emotional, scientific, or otherwise. The only recourse for the common person is to recall exactly the freedoms that I the government...sonic boom is even less a hazard to hearing than the much higher intensity airbag impulses. 154: Comment noted. This is not the opinion of the

  9. Environmental Impact Statement Supersonic Flight Operations in the Valentine Military Operations Area, Holloman Air Force Base, New Mexico

    Science.gov (United States)

    1983-01-01

    miles from the southern border of the MOA. In addition, there is no mention of the many Mexican ejidos and settlements, ranches, and farms along the...mention is made of the many Mexican ejidos and settlements, ranches and farms along the Rio Grande in Mexico. The above population figures are 1980 census

  10. Environmental Impact Analysis Process. Final Environmental Impact Statement Supersonic Flight Operations in the Valentine Military Operations Area

    Science.gov (United States)

    1983-11-04

    population 13,000, just 15 miles from the southern border of the MOA. In addition, there is no mention of the many Mexican ejidos and settlements, ranches...Southern border. Also, 5 no mention is made of the many Mexican ejidos and settlements, ranches and farms along the Rio Grande in Mexico. 3 The above

  11. Analyzing the structure of the optical path difference of the supersonic film cooling

    Science.gov (United States)

    Ding, Haolin; Yi, Shihe; Fu, Jia; He, Lin

    2016-10-01

    While high-speed aircraft are flying in the atmosphere, its optical-hood is subjected to severe aerodynamic heating. Supersonic film cooling method can effectively isolate external heating, but the flow structures formed by the supersonic film cooling can cause the beam degradation and affect the imaging quality. To research the aero-optics of supersonic film cooling, an experimental model was adopted in this paper, its mainstream Mach number 3.4, designed jet Mach number 2.5, measured jet Mach number 2.45. High-resolution images of flow were acquired by the nano-based planar laser scattering (NPLS) technique, by reconstructing the density field of supersonic film cooling, and then, the optical path difference (OPD) were acquired by the ray-tracing method. Depending on the comparison between K-H vortex and OPD distribution, the valleys of OPD correspond to the vortex `rollers' and the peaks to the `braids'. However, the corresponding relationship becomes quite irregular for the flow field with developed vortices, and cannot be summarized in this manner. And then, the OPD were analyzed by correlation function and structure function, show that, there is a relationship between the shape of OPD correlation function and the vortex structure, the correlation function type changed with the development of the vortex. The correctness that the mixing layer makes a main contribution to the aero-optics of supersonic film cooling was verified, and the structure function of aero-optical distortion has a power relationship that is similar to that of atmospheric optics. At last, the power spectrum corresponding to the typical region of supersonic film cooling were acquired by improved periodgram.

  12. FLOW REGIMES BELOW AERATORS FOR DISCHARGE TUNNELS

    Institute of Scientific and Technical Information of China (English)

    MA Fei; WU Jian-hua

    2012-01-01

    The flow regimes below an aerator influence directly the air entrainment and the cavitation damage control.Based on the theoretical considerations,the experiments of the aerator for a discharge tunnel were conducted,and the relationships between the flow regime and hydraulic and geometric parameters were investigated.The results showed that,there are two kinds of threshold values for the flow regime conversions.One is Fr1-2 standing for the conversion from the fully filled cavity to the partially filled cavity,and the other is Fr2-3 which shows the change from the partially filled cavity to the net air cavity.Two empirical expressions were obtained for the conversions of the flow regimes,which can be used in the designs of the aerators.

  13. US Forest Service LANDFIRE Historical Fire Regimes

    Data.gov (United States)

    US Forest Service, Department of Agriculture — Historical fire regimes, intervals, and vegetation conditions are mapped using the Vegetation Dynamics Development Tool (VDDT). These data support fire and landscape...

  14. Figure 1: Basal-Bolus Regime

    African Journals Online (AJOL)

    Siegal_D

    Breakfast. Lunch. Dinner. Bedtime. Plasma insulin concentrations over time with a twice daily insulin mix regime .... Hypoglycaemia. Frequency, severity, awareness, precipitants, driving, ... Post GDM, family members, IGT etc. EXAMINATION.

  15. Regimes of validity for balanced models

    Science.gov (United States)

    Gent, Peter R.; McWilliams, James C.

    1983-07-01

    Scaling analyses are presented which delineate the atmospheric and oceanic regimes of validity for the family of balanced models described in Gent and McWilliams (1983a). The analyses follow and extend the classical work of Charney (1948) and others. The analyses use three non-dimensional parameters which represent the flow scale relative to the Earth's radius, the dominance of turbulent or wave-like processes, and the dominant component of the potential vorticity. For each regime, the models that are accurate both at leading order and through at least one higher order of accuracy in the appropriate small parameter are then identified. In particular, it is found that members of the balanced family are the appropriate models of higher-order accuracy over a broad range of parameter regimes. Examples are also given of particular atmospheric and oceanic phenomena which are in the regimes of validity for the different balanced models.

  16. The Two Regimes of Postwar Shipping

    DEFF Research Database (Denmark)

    Iversen, Martin Jes; Tenold, Stig

    2014-01-01

    The aim of this article is to illustrate the most important changes in the regulatory framework of the shipping sector from the 1960s to 2010, and to analyse the basis for, and effects of, these changes. In order to explain how the transformation has occurred, we use two traditional maritime...... nations—Denmark and Norway—as case studies. First, we introduce the two regimes of Danish and Norwegian shipping: ‘the national regime’ from the early 1960s to the mid-1970s; and ‘the competitive regime’, which was fully established by the middle of the 1990s and still persists. Then, we briefly sketch...... the bargaining that accompanied the shift from the national regime to the competitive regime. Specifically, we show that the new regime primarily accommodated the interests of private actors such as shipping companies, rather than the interests of the authorities and the trade unions....

  17. Exchange rate regimes and external financial stability

    Directory of Open Access Journals (Sweden)

    Stoica Ovidiu

    2016-01-01

    Full Text Available Financial stability within the framework of the global financial crisis has become a common topic for researchers and practitioners. In order to analyse the impact of exchange rate regimes on financial stability we use both the de jure and de facto exchange rate classifications. We apply the model to a 1999-2010 annual data sample for 135 countries and territories, grouped by the level of economic development. Our second focus is the investigation of the effects of the exchange rate regimes in three economic integration areas (member countries of the European Union 27, the Southern Common Market, and the Association of Southeast Asian Nations on financial stability. Our results generally support the central banks’ concerns that the flexibility of exchange rate regimes should be reduced in order to sustain financial stability; however, the findings are not robust when using alternative regime classifications.

  18. Bisphosphonate ISS Flight Experiment

    Science.gov (United States)

    LeBlanc, Adrian; Matsumoto, Toshio; Jones, Jeffrey; Shapiro, Jay; Lang, Thomas; Shackleford, Linda; Smith, Scott M.; Evans, Harlan; Spector, Elizabeth; Ploutz-Snyder, Robert; Sibonga, Jean; Keyak, Joyce; Nakamura, Toshitaka; Kohri, Kenjiro; Ohshima, Hiroshi; Moralez, Gilbert

    2014-01-01

    The bisphosphonate study is a collaborative effort between the NASA and JAXA space agencies to investigate the potential for antiresorptive drugs to mitigate bone changes associated with long-duration spaceflight. Elevated bone resorption is a hallmark of human spaceflight and bed rest (common zero-G analog). We tested whether an antiresorptive drug in combination with in-flight exercise would ameliorate bone loss and hypercalcuria during longduration spaceflight. Measurements include DXA, QCT, pQCT, and urine and blood biomarkers. We have completed analysis of 7 crewmembers treated with alendronate during flight and the immediate postflight (R+exercise device (ARED) during their missions. We previously reported the pre/postflight results of crew taking alendronate during flight (Osteoporosis Int. 24:2105-2114, 2013). The purpose of this report is to present the 12-month follow-up data in the treated astronauts and to compare these results with preliminary data from untreated crewmembers exercising with ARED (ARED control) or without ARED (Pre-ARED control). Results: the table presents DXA and QCT BMD expressed as percentage change from preflight in the control astronauts (18 Pre-ARED and the current 5 ARED-1-year data not yet available) and the 7 treated subjects. As shown previously the combination of exercise plus antiresorptive is effective in preventing bone loss during flight. Bone measures for treated subjects, 1 year after return from space remain at or near baseline values. Except in one region, the treated group maintained or gained bone 1 year after flight. Biomarker data are not currently available for either control group and therefore not presented. However, data from other studies with or without ARED show elevated bone resorption and urinary Ca excretion while bisphosphonate treated subjects show decreases during flight. Comparing the two control groups suggests significant but incomplete improvement in maintaining BMD using the newer exercise

  19. Portfolio Selection with Jumps under Regime Switching

    Directory of Open Access Journals (Sweden)

    Lin Zhao

    2010-01-01

    Full Text Available We investigate a continuous-time version of the mean-variance portfolio selection model with jumps under regime switching. The portfolio selection is proposed and analyzed for a market consisting of one bank account and multiple stocks. The random regime switching is assumed to be independent of the underlying Brownian motion and jump processes. A Markov chain modulated diffusion formulation is employed to model the problem.

  20. International Experiences with Different Monetary Policy Regimes

    OpenAIRE

    Mishkin, Frederic S.

    1999-01-01

    In recent years a growing consensus has emerged for price stability as the overriding, long-run goal of monetary policy. However, despite this consensus, the following question still remains: how should monetary policy be conducted to achieve the price stability goal? This paper examines the experience with different monetary policy regimes currently in use in a number of countries to shed light on this question. A central feature of all of the monetary regimes discussed here is the ise of a ...