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AIAA JOURNAL 2005年第12期43卷 2558-2564页

作者： Wright, MJ Bose, D Palmer, GE Levin, E NASA Ames Res Ctr Reacting Flow Environm Branch Moffett Field CA 94035 USA NASA Ames Res Ctr Eloret Corp Moffett Field CA 94035 USA

A review of the best-available data for calculating a complete set of binary collision integral data for the computation of the mixture transport properties (viscosity, thermal conductivity, and ordinary and thermal diffusion) of 13-species weakly ionized air is presented. Although the fidelity of the data varies, all collision integrals presented herein, except for electron-neutral interactions, are estimated to be accurate to within 25% over the temperature range of interest (300-15,000 K) for reentry and laboratory plasmas. In addition, most of the dominant atom-atom and atom-ion interactions for dissociated weakly ionized air were derived from ab initio methods that are estimated to be accurate to within 10%. The accuracy and valid temperature range for electron-neutral interactions vary because of scarcity of the required cross-sectional data.

关键词： Conductivity Coefficients Thermal Conductivity Thermodynamic Equilibrium Thermal Diffusion Polarization Earth computational fluid dynamics code Thermal Diffusion Coefficient Chapman Enskog Theory Numerical Integration

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Transient Analysis for Hypersonic Inlet Accelerative Restarting Process

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JOURNAL OF SPACECRAFT AND ROCKETS 2017年第2期54卷 376-385页

作者： Su, Wei-Yi Hu, Zhiwei Tang, Piao-Ping Chen, Yun Nanjing Univ Aeronaut & Astronaut Jiangsu Prov Key Lab Aerosp Power Syst Coll Energy & Power Engn Nanjing 210016 Peoples R China Univ Southampton Fac Engn & Environm Aerodynam & Flight Mech Res Grp Southampton SO17 1BJ Hants England

A three-dimensional computational fluid dynamics code that solves the unsteady compressible Reynolds-averaged Navier-Stokes equations was used to investigate the transient accelerative restarting processes of a planar hypersonic inlet. The characteristics of the accelerative restarting process were analyzed, and they revealed that the wall pressure time histories could be used to monitor whether the hypersonic inlet restarted. In addition, the effects of acceleration and flight trajectories on the transient accelerative process were studied. The results showed that the process of the disappearance of the separation bubble was delayed as the acceleration was increased. As a result, the corresponding flight Mach number at which the inlet restarted increased accordingly. The unsteady simulation results also indicated that the trajectory had great impact on the accelerative restarting process.

关键词： Hypersonic Inlets Freestream Mach Number Reynolds Averaged Navier Stokes computational fluid dynamics code Flight Trajectory Scramjet Engines Skin Friction Coefficient Hysteresis Loops Static Pressure Flow Conditions

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Computation of Aircraft Stability Derivatives Using an Automatic Differentiation Adjoint Approach

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AIAA JOURNAL 2011年第12期49卷 2737-2750页

作者： Mader, Charles A. Martins, Joaquim R. R. A. Univ Toronto Inst Aerosp Studies Toronto ON M3H 5T6 Canada Univ Michigan Dept Aerosp Engn Ann Arbor MI 48109 USA

This paper presents a method for the computation of the static and dynamic stability derivatives of arbitrary aircraft configurations. Three-dimensional computational fluid dynamics are used in this method to simulate the flow characteristics around the configuration, and a moving-grid formulation is included in the flow solver to handle the rotational physics necessary for the computation of the dynamic derivatives. To obtain the stability derivatives, the computational fluid dynamics code is differentiated using the automatic differentiation adjoint (ADjoint) approach. This approach enables the efficient and accurate computation of derivatives for a wide variety of variables, including the dynamic model states that are typical of the stability derivatives. To demonstrate the effectiveness of this approach, stability derivatives are computed for a NACA 0012 airfoil and an ONERA M6 wing.

关键词： Aerodynamic Characteristics Detached Eddy Simulation NACA 0012 computational fluid dynamics code Aircraft Configurations Flow Characteristics Lift Coefficient Reynolds Averaged Navier Stokes High Performance Computing Two Dimensional Flow

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Open-Source Direct Simulation MonteCarlo Chemistry Modeling for Hypersonic Flows

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AIAA JOURNAL 2015年第6期53卷 1670-1680页

作者： Scanlon, Thomas J. White, Craig Borg, Matthew K. Palharini, Rodrigo C. Farbar, Erin Boyd, Iain D. Reese, Jason M. Brown, Richard E. Univ Strathclyde Dept Mech & Aerosp Engn James Weir Fluids Lab Glasgow G1 1XJ Lanark Scotland Univ Michigan Dept Aerosp Engn Ann Arbor MI 48109 USA Univ Edinburgh Sch Engn Edinburgh EH9 3HL Midlothian Scotland Univ Strathclyde Dept Mech & Aerosp Engn Ctr Future Air Space Transportat Technol Glasgow G1 1XJ Lanark Scotland

An open-source implementation of chemistry modeling for the direct simulation Monte Carlo method is presented. Following the recent work of Bird (Bird, G. A., " The Q-K Model for Gas Phase Chemical Reaction Rates," Physics of fluids, Vol. 23, No. 10, 2011, Paper 106101), an approach known as the quantum-kinetic method has been adopted to describe chemical reactions in a five-species air model using direct simulation Monte Carlo procedures based on microscopic gas information. The quantum-kinetic technique has been implemented within the framework of the dsmcFoam code, a derivative of the open-source computational-fluid-dynamics code OpenFOAM. Results for vibrational relaxation, dissociation, and exchange reaction rates for an adiabatic bath demonstrate the success of the quantum-kinetic model implementation in dsmcFoam when compared with analytical solutions for both inert and reacting conditions. A comparison is also made between the quantum-kinetic and total collision energy chemistry approaches for a hypersonic flow benchmark case.

关键词： Nonequilibrium Flows Direct Simulation Monte Carlo computational fluid dynamics code Conservation of Mass Vibrational Energy Nonreacting Flow Stagnation Streamlines Thermodynamic Equilibrium Activation Energy Bhatnagar Gross Krook

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Characteristics of Y-shaped rectangular diffusing duct at different inflow conditions

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JOURNAL OF AIRCRAFT 2005年第1期42卷 113-120页

作者： Patel, T Singh, SN Seshadri, V Indian Inst Technol Dept Appl Math New Delhi 110 016 India

Y-Shaped diffusing intake ducts are extensively used for engines in fighter aircrafts. These ducts normally operate under steady and symmetric conditions but, during some maneuvers, the inflow becomes asymmetric. An attempt has been made to analyze the flow characteristics within the Y-shaped rectangular diffusing duct having a turn angle of 22.5/22.5 deg and an overall area ratio of 2.0 with a circular outlet. The inlet of this duct is through two rectangular openings with an aspect ratio of 2.0. Detailed analyses are carried out using the computational, fluid dynamics code FLUENT for skewed axial velocity distribution in one limb and uniform flow in the other limb at average inlet velocities of 30, 60, and 90 m/s. The results show that static pressure recovery reduces with increases in skewness, and strong secondary flows are observed throughout the length of the diffuser with a highly complex flow pattern at, the merging plane. The performance characteristics of the Y-shaped duct with uniform flow at the inlet of the two limbs is found to be independent of Reynolds number over the range analyzed. Longitudinal velocity contours show the deflection of the flow toward the outer wall all along the length of the diffuser for all inflow conditions.

关键词： Flow Characteristics Incompressible Flow Aerodynamic Testing Static Pressure FLUENT Kinetic Energy Aspect Ratio Turbulence Models Fighter Aircraft computational fluid dynamics code

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Preliminary Investigation on Lithium Hydride as Fuel for Solid-Fueled Scramjet Engines

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JOURNAL OF PROPULSION AND POWER 2009年第4期25卷 875-884页

作者： Simone, D. Bruno, C. Univ Roma La Sapienza Dept Mech & Aeronaut I-00184 Rome Italy

The aim of this work is to study the combustion of a LiH grain in a supersonic airstream, as a preliminary to investigate its potential as fuel in a solid-fueled scramjet. This hydride is interesting because it reacts exothermically with many substances and contains hydrogen, suggesting its use when a much higher density (compared with that of LH2) would be beneficial. In fact, LiH releases H-2 and Li by thermal decomposition;at the same time, the Li produced behaves as a highly energetic fuel in the presence of a high-temperature airstream. Because of the scarce data present in literature, the thermochemical properties of LiH and its decomposition were calculated, estimated, or modeled, and issues associated with its combustion in a hot supersonic stream were investigated;a simplified physical model describing its vaporization and combustion was built that was successively simulated by means of a computational fluid dynamics code. Results show that LiH is an ideal candidate for solid-fueled-scramjet applications, behaving not only as a high-energy-density bifuel system, but also as a safe and compact hydrogen carrier. An intense flame zone is predicted to be present over the decomposing surface and downstream of the grain;the flame is stable and high temperatures (on the order of 2900 K) are obtainable. Moreover, specific impulse and thrust density predicted at a flight Mach = 7 are also interesting, being 10,000 and 200-300 m/s, respectively.

关键词： Solid Fuels Scramjet Combustion Chambers Fuels Thermal Decomposition Energy Density computational fluid dynamics code Combustors Compressible Flow Adiabatic Flame Temperature Chemical Equilibrium

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Formation and stability of near Chapman-Jouguet standing oblique detonation waves

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AIAA JOURNAL 2005年第7期43卷 1591-1604页

作者： Fusina, G Sislian, JP Parent, B Def Res & Dev Canada Ottawa ON K1A 0Z4 Canada Univ Toronto Downsview ON M3H 5T6 Canada Seoul Natl Univ Seoul 151744 South Korea

A numerical investigation of the behavior of standing oblique detonation waves (ODWs) near the Chapman-Jouguet (minimum entropy) point is the main purpose of this investigation. The laminar, two-dimensional Navier-Stokes equations coupled with a nonequilibrium hydrogen-air combustion model based on chemical kinetics are used to represent the physical system. The equations are solved with the window allocatable resolver for propulsion computational fluid dynamics code (Parent, B., and Sislian, J. P., "The Use of Domain Decomposition in Accelerating the Convergence of Quasihyperbolic Systems," journal of computational Physics, Vol. 179, No. 1, 2002, pp. 140-169). A time-accurate simulation of the formation of a standing ODW near the Chapman-Jouguet condition yields a nonoscillatory, stable structure. The stability of the ODW to inhomogeneities in the oncoming fuel-air mixture is assessed through other time-accurate simulations by artificially introducing small disturbances consisting of pure air just upstream of the ODW structure. The ODW is shown to be resilient to these disturbances. The induction process and radical formation within the ODW structure are also analyzed.

关键词： Detonation Waves Reaction Rate Constant Navier Stokes Equations Entropy computational fluid dynamics code Combustion Products Blunt Bodies Shcramjet Rankine Hugoniot Equations Numerical Simulation

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Aerodynamic database development for Mars Smart Lander vehicle configurations

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JOURNAL OF SPACECRAFT AND ROCKETS 2006年第2期43卷 303-310页

作者： Bobskill, GJ Parikh, PC Prabhu, RK Tyler, ED NASA Langley Res Ctr Verhicle Anal Branch Syst Anal & Concepts Directorate Hampton VA 23681 USA NASA Langley Res Ctr Configurat Aerodynam Branch Res & Technol Directorate Hampton VA 23681 USA Lockheed Marting Engn & Sci Co Hampton VA 23681 USA Swales Aerosp Hampton VA 23681 USA

An aerodynamic database has been generated for the Mars Smart Lander shelf-all configuration. Beginning with all effort to validate the computational tools against sets of experimental data, the static aerodynamic database was constructed by correcting experimental data to Mars atmospheric flight conditions at supersonic speeds, in addition to performing discrete hypersonic analyses in the continuum and noncontinuum atmospheric regimes. Three different computational fluid dynamics codes, two based on unstructured grid technology and one an established and validated structured grid-based code, were used. As part of this database development, the results for the Mars continuum atmosphere were validated with experimental data and comparisons made where applicable. The validation with the Unitary experimental data, the use of intermediate check analyses, and the validation with the Mach 6 CF4 experimental data provided a higher confidence in the ability of the computational analyses to provide accurate aerodynamic data for the determination of static trim characteristics for longitudinal stability within the continuum and noncontinuum atmospheric regimes. The analyses of the noncontinuum regime showed the existence of multiple trim angles of attack that can be unstable or stable trial points. These trends assisted in the development of all entry controller for a nominal trajectory.

关键词： Freestream Mach Number Angle of Attack computational fluid dynamics code Knudsen Numbers Sideslip Angle Ballistic Coefficient Unstructured Grid Supersonic Speed Lift to Drag Ratio Longitudinal Stability

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Industrial computational fluid dynamics Tools for the Evaluation of Aerodynamic Coefficients

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JOURNAL OF AIRCRAFT 2009年第6期46卷 1973-1983页

作者： Necci, Carlo Ceresola, Nicola Guglieri, Giorgio Quagliotti, Fulvia Alenia Aeronaut CFD Grp Numer Simulat Lab I-10146 Turin Italy Politecn Torino Dipartimento Ingn Aeronaut & Spaziale I-10129 Turin Italy

An automatic differentiation technique is applied here to an industrial computational fluid dynamics code with the goal of efficiently evaluating aerodynamic coefficients. Basic concepts about the numerical technique to automatically differential code are first discussed, and then methodologies;to apply the capabilities of the Institut National tie Recherche en Informatique et en Automatique derivation tool to an industrial finite volume Solver are discussed. Afterward, two examples of application to representative two-dimensional and three-dimensional test case,;are shown and, for each one, comparisons are carried out between the results gathered using the automatic differentiation and the classical second-order finite difference technique for the evaluation of derivatives. Such comparison highlights the capability of automatic differentiation to produce reliable results even it applied to complex configurations and in very complex numerical structures. Finally, tradeoff considerations are made as a conclusion.

关键词： Aerodynamic Characteristics Courant Friedrichs Lewy Angle of Sideslip computational fluid dynamics code Aerodynamic Efficiency Message Passing Interface Aeroplane Yaw Wing Root Boundary Layer Thickness

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Flow simulation around an airfoil by lattice Boltzmann method on generalized coordinates

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AIAA JOURNAL 2005年第9期43卷 1968-1973页

作者： Imamura, T Suzuki, K Nakamura, T Yoshida, M Japan Aerosp Explorat Agcy Computat Aerodynam & Optimizat Team Ctr Informat Technol Inst Space Technol & Aeronaut Tokyo 1828522 Japan Univ Tokyo Dep Adv Energy Div Transdisciplinary Sci Grad Sch Frontier Sci Tokyo 1130033 Japan

Flow simulations around. an airfoil (NACA0012) using the lattice Boltzmann method (LBM) are performed. Originally, the LBM is an incompressible flow solver on orthogonal coordinates. However, to resolve the boundary layer of the airfoil accurately, the algorithm is extended to generalized coordinates. Also, a suitable wall boundary condition is introduced for generalized coordinates. First, the numerical method is validated at a relatively small Reynolds number (Re = 500). The velocity profile of the boundary layer is compared in detail with the computational fluid dynamics code CFL3D (developed at NASA Langley Research Center) results, and consistent results are obtained. Second, the method is combined with the Baldwin-Lomax turbulence model and results at relatively high Reynolds number (Re= 5 x 10(5)) are shown. The results are in good agreement with the experimental data. With the same grid resolution, the method can solve high-Reynolds-number flows as accurately as traditional Navier-Stokes solvers.

关键词： Airfoil Lattice Boltzmann Equation Aerodynamic Coefficients Spalart Allmaras Turbulence Model computational fluid dynamics code Adaptive Mesh Refinement Flow Separation Incompressible Flow Velocity Profiles NASA Langley Research Center

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