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Streamline-Based Transition Prediction Techniques in an Unstructured computational fluid dynamics code

AIAA JOURNAL 2017年第5期55卷 1548-1564页

作者： Krumbein, Andreas Krimmelbein, Normann Grabe, Cornelia German Aerosp Ctr DLR Inst Aerodynam & Flow Technol Ctr Comp Applicat Aerosp Sci & Engn Bunsenstr 10 D-37073 Gottingen Germany German Aerosp Ctr DLR Inst Aerodynam & Flow Technol Ctr Comp Applicat Aerosp Sci & Engn Lilienthalpl 7 D-38108 Braunschweig Germany

An unstructured flow solver has been equipped with transition prediction techniques based on different streamline-based approaches, applying the e(N) method for the estimation of the points of transition onset. The integration paths for the N-factor integration can be approximated using lines parallel to the direction of the oncoming flow for some configurations. If arbitrary three-dimensional geometries are to be computed, the local flow direction can be taken into account. The calculation of the laminar boundary-layer data can either be carried out applying a suitable laminar boundary-layer method or by direct determination from the field solution of the unstructured computational fluid dynamics code. The development and characteristics of the two streamline-based transition prediction techniques, their elements, and properties are described. The focus is put on the latest achievements in the development activities of the two approaches and on their application to various configurations, most of them of industrial relevance. In addition, the specific advantages and shortcomings of the different approaches are discussed. Eventually, a number of challenges for the future development and extension of the transition prediction techniques against the background of a multidisciplinary simulation environment and for the application of computational fluid dynamics solvers to cruise and high-lift aircraft configurations are specified.

关键词： computational fluid dynamics code Laminar Turbulent Transition Direct Numerical Simulation Aircraft Configurations Industrial Relevance Reynolds Averaged Navier Stokes Natural Laminar Flow Lift Coefficient Hybrid Laminar Flow Control Parabolized Stability Equations

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Development of an Anti-Icing computational fluid dynamics code

Development of an Anti-Icing Computational Fluid Dynamics Co...

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AIAA Science and Technology Forum and Exposition (AIAA SciTech)

作者： Maudsley, Donovan Etele, J. Carleton Univ Mech Engn Ottawa ON K1S 5B6 Canada Carleton Univ Mech & Aerosp Engn Ottawa ON K1S 5B6 Canada

ISBN: (数字)9781624105951

ISBN: (纸本)9781624105951

Ice accretion on aircraft surfaces can negatively affect aircraft performance and stability, and result in deteriorating flight safety. Icing codes developed over the past three decades have helped reduce the risks posed by ice accretion. Recently dielectric barrier discharge (DBD) plasma systems have been proposed as a solution to both flow control in near-stall conditions and wing anti-icing. Numerically modelling ice accretion and DBD anti-icing will prove invaluable to the aircraft development process. This paper outlines the general requirements for such an ice accretion code and how these requirements will be met using the open source CFD software OpenFOAM and MATLAB.

关键词： Anti Icing System Dielectric Barrier Discharge computational fluid dynamics Supercooled Large Droplets MATLAB computational fluid dynamics code Aircraft Performance Lift Coefficient Conjugate Heat Transfer Stagnation Point

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Soft-Finite-Element-Method-Driven Multiphysics Airfoil Optimization

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AIAA JOURNAL 2025年第1期63卷 148-161页

作者： Nguyen, Van-Dung Naharro, Pablo-Sanchez Pena, Jose-Maria Jerusalem, Antoine Univ Oxford Dept Engn Sci Oxford OX1 3PJ England Lurtis Ltd Wood Ctr Innovat Stansfeld Pk Quarry Rd Oxford OX3 8SB England Univ Oxford Dept Engn Sci Oxford OX1 3PJ England

The soft finite element method (SoftFEM) was recently developed as an efficient black-box engineering optimization framework combining population-based evolutionary global optimization and a local search technique using a hybrid self-adaptive strategy. This framework simultaneously leverages exploration and exploitation without the need to know a priori which strategy is best fitted to the problem at hand. In this work, we first improve SoftFEM by replacing the original differential evolution by the so-called success-history-based adaptive differential evolution. The developed framework is then applied to optimize the aerodynamic performance of 1) an airfoil, 2) a wing, and 3) the fluid-structure interaction problem of an airfoil with a flexible trailing edge. In the first two cases, the open-source computational fluid dynamics code OpenFOAM is considered to evaluate the aerodynamic characteristics of the airfoil, while in the latter case, we combine OpenFOAM and MuPhiSim-our recently released open-source code for computational solids mechanics-to conduct fluid-structure interaction simulations. The results demonstrate that this approach can effectively find optimal solutions with improved aerodynamic performance in all three cases. The proposed framework has the potential to significantly impact the design and optimization of aerodynamic systems in complex design spaces. In particular, new systems involving soft components and soft-hard junctions would benefit from a seamless application of the developed framework to their optimization.

关键词： Aerofoil Aerodynamic Performance fluid Structure Interaction Aerodynamic Design Optimization Finite Element Method Aircraft Wing Design Flight Recorder computational fluid dynamics code Multidisciplinary Design Optimization Solid Mechanics

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Correlation-Based Transition Modeling for Unstructured Parallelized computational fluid dynamics codes

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AIAA JOURNAL 2009年第12期47卷 2894-2906页

作者： Langtry, Robin B. Menter, Florian R. Boeing Co Enabling Technol & Res Seattle WA 98124 USA ANSYS Germany Fluids Business Unit D-83624 Otterfing Germany

A new correlation-based transition model has been developed, which is built strictly on local variables. As a result, the transition model is compatible with modern computational fluid dynamics techniques such as unstructured grids and massively parallel execution. The model is based on two transport equations, one for intermittency and one for a transition onset criterion in terms of momentum-thickness Reynolds number. A number of validation papers have been published on the basic formulation of the model. However, until now the full model correlations have not been published. The main goal of the present paper is to publish the full model and release it to the research community so that it can continue to be further validated and possibly extended or improved. Included in this paper are a number of test cases that can be used to validate the implementation of the model in a given computational fluid dynamics code. The authors believe that the current formulation is a significant step forward in engineering transition modeling, as it allows the combination of transition correlations with general-purpose computational fluid dynamics codes. There is a strong potential that the model will allow the first-order effects of transition to be included in everyday industrial computational fluid dynamics simulations.

关键词： Freestream Mach Number computational fluid dynamics code Unstructured Grid Laminar to Turbulent Transition Reynolds Averaged Navier Stokes Turbulence Kinetic Energy High Pressure Turbine Lift Coefficient Skin Friction Coefficient Velocity Profiles

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Investigation of metallized and nonmetallized hydroxyl terminated polybutadiene/hydrogen peroxide hybrid rockets

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JOURNAL OF PROPULSION AND POWER 2007年第2期23卷 476-486页

作者： Farbar, E. Louwers, J. Kaya, T. Carleton Univ Ottawa ON K1S 5B6 Canada Cesaroni Technol Inc Gormley ON L0H 1G0 Canada

Results from 15 static test firings of lab scale hybrid rocket motors using 90% concentrated unstabilized hydrogen peroxide as an oxidizer with hydroxyl terminated polybutadiene fuel are presented. Thirteen of those tests used aluminum or aluminum/magnesium alloy additive in the fuel. The performance characteristics of the propellant combinations were determined. The experimental results indicated combustion efficiencies of 0.72-0.89 and regression rates of 0.5-1.3 mm/s for the metallized fuel combinations. A correlation of the regression rate data for the metallized propellants deviated from that which was derived for turbulent convective heat transfer dominated behavior. A numerical model of the hydrogen peroxide/nonmetallized hydroxyl terminated polybutadiene motor was built using a commercial computational fluid dynamics code. The model was combined with an in-house code to predict the regression rate of the propellant combination, and the flowfield characteristics at the initial operating conditions for two of the experimental tests. The results of the model indicated that the proposed numerical model is a promising tool for mapping the temporal and spatial variation of the regression rate in hybrid motors operating with homogeneous hydrocarbon fuels.

关键词： Hydroxyl Terminated Polybutadiene Hybrid Rocket Bipropellants Combustion Instability Numerical Modeling Convective Heat Transfer Hybrid Rocket Motor Hydrocarbon Fuels computational fluid dynamics code Magnesium Alloys

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AEROTHERMODYNAMIC MEASUREMENT AND PREDICTION FOR MODIFIED ORBITER AT MACH-6 AND MACH-10

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JOURNAL OF SPACECRAFT AND ROCKETS 1995年第5期32卷 737-748页

作者： MICOL, JR NASA Langley Research Center Hampton VA

Detailed heat-transfer rate distributions measured laterally over the windward surface of an orbiter-like configuration using thin-film resistance heat-transfer gauges and globally using the newly developed relative intensity, two-color thermographic phosphor technique are presented for Mach 6 and 10 in air. The angle of attack was varied from 0 to 40 deg, and the freestream Reynolds number based on the model length was varied from 4 x 10(5) to 6 x 10(6) at Mach 6, corresponding to laminar, transitional, and turbulent boundary layers;the Reynolds number at Mach 10 was 4 x 10(5), corresponding to laminar flow. The primary objective of the present study was to provide detailed benchmark heat-transfer data for the calibration of computational fluid-dynamics codes. Predictions from a Navier-Stokes solver referred to as the Langley aerothermodynamic upwind relaxation algorithm and an approximate boundary-layer solving method known as the axisymmetric analog three-dimensional boundary Layer code are compared with measurement. In general, predicted laminar heat-transfer rates are in good agreement with measurements.

关键词： Aerothermodynamic Measurements Heat Transfer Coefficients Angle of Attack Three Dimensional Boundary Layer Reynolds Number Thin Films Hypersonic Flows Navier Stokes Solver computational fluid dynamics code Bow Shock

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Development of hybrid simulation for supersonic chemical oxygen-iodine laser

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AIAA JOURNAL 2007年第1期45卷 90-97页

作者： Endo, Masamori Masuda, Taizo Uchiyama, Taro Tokai Univ Dept Phys Sch Sci Hiratsuka Kanagawa 2591292 Japan Keio Univ Fac Sci & Engn Dept Syst Design Engn Yokohama Kanagawa 2238522 Japan

A numerical simulation method for a supersonic chemical oxygen-iodine laser is developed. The model is a combination of a three-dimensional computational fluid dynamics code without kinetics and a detailed one-dimensional, multiple-leaky-stream-tubes kinetics code. In the proposed method, the detailed flowfield characteristic is calculated by solving a full Navier-Stokes equation that does not involve chemical reactions, and the resultant temperature, velocity, and mixing characteristics are input to the kinetics code as its boundary conditions. A "nonuniform coefficient" is introduced to transform the fluid-dynamic mixing to the diffusive mixing term of the kinetics code. As a result, precise predictions of the gain distribution and laser output are given with a reasonable computational cost. The developed model is applied to the X-wing-type supersonic mixing chemical oxygen-iodine laser, which we have developed, and the calculated gain and output power are compared with the experimental results. The excellent agreements of calculated and experimental results show the validity of the developed method.

关键词： Chemical Oxygen Iodine Lasers Numerical Simulation Navier Stokes Simulation computational fluid dynamics code Transmittance Stagnation Temperature Vortices Stimulated Emission Vortex Generators Supersonic Flow

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Effects of Continuum Breakdown on the Surface Properties of a Hypersonic Sphere

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JOURNAL OF THERMOPHYSICS AND HEAT TRANSFER 2009年第4期23卷 660-673页

作者： Holman, Timothy D. Boyd, Iain D. Univ Michigan Dept Aerosp Engn Ann Arbor MI 48109 USA

This study investigates the effects of continuum breakdown on the surface aerothermodynamic properties (pressure, shear, heat transfer rate) of a sphere in Mach 10, 25, and 45 flows of nitrogen gas in regimes varying from continuum to rarefied gas. A rotational energy relaxation model is employed in the computational fluid dynamics code and is tested to confirm its accuracy. As the global Knudsen number is increased, from continuum flow to a rarefied gas, the amount of continuum breakdown seen in the flow and on the surface is increased. This increase in continuum breakdown affects the surface properties, such that an increase in the differences between computational fluid dynamics and direct simulation Monte Carlo method is observed. As the Mach number is increased, the amount of continuum breakdown observed in the flow is increased, but the gradient length local Knudsen number stays approximately constant. Even though the amount of continuum breakdown has increased, the difference between computational fluid dynamics and direct simulation Monte Carlo method remains relatively constant. The last part of this study compares the results of the sphere with that of the analogous cylinder case. At the same global Knudsen number, the differences in the surface properties between computational fluid dynamics and direct simulation Monte Carlo method increase when the simulation is run axisymmetrically.

关键词： Surface Properties Direct Simulation Monte Carlo CFD Simulation Pressure Coefficient Freestream Conditions Nonequilibrium Flows Heat Transfer Coefficients Aerothermodynamics computational fluid dynamics code Shear Stress

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Numerical Simulations and Measurements of the Helicopter Wake in Ground Effect

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JOURNAL OF AIRCRAFT 2017年第1期54卷 209-219页

作者： Sugiura, Masahiko Tanabe, Yasutada Sugawara, Hideaki Matayoshi, Naoki Ishii, Hirokazu Japan Aerosp Explorat Agcy Next Generat Aeronaut Innovat Hub Ctr 6-13-1 Osawa Mitaka Tokyo 1810015 Japan Ryoyu Syst Aerosp Engn Solut Div Minato Ku 6-19 Oe Cho Nagoya Aichi 4550024 Japan Japan Aerosp Explorat Agcy Flight Res Unit 6-13-1 Osawa Mitaka Tokyo 1810015 Japan

When a helicopter takes off, lands, or makes hovering or taxiing flights in ground effect, its downwash interferes with the ground. Encounters with such highly turbulent helicopter wakes have resulted in the two small fixed-wing aircraft crashes in the United Kingdom. Due to these accidents, the Japan Aerospace Exploration Agency is investigating the helicopter wake structure in ground effect, especially during taxiing, by means of computational fluid dynamics and flight testing. The base computational fluid dynamics code is structured grid solver rFlow3D, which has systematically been developed for helicopter applications at the Japan Aerospace Exploration Agency. The rFlow3D solver is a highly versatile computational fluid dynamics code that can numerically simulate flows around helicopters with a wide range of Reynolds and Mach numbers and can perform rotor trim analysis with elastic blade deformations. In the flight experiment described herein, the Japan Aerospace Exploration Agency research helicopter H145 (EC145, BK117 C-2) performed taxiing above a runway, and its wakes were measured by Light Detection and Ranging and ultrasonic anemometers. The variation of the characteristic wake structure with the advance ratio was clearly revealed in the computational fluid dynamics and was supported indirectly by the flight experiment results.

关键词： Helicopter Rotor Numerical Simulation Fixed Wing Aircraft Anemometer LIDAR Flight Testing Runways Japan Aerospace Exploration Agency Aerodynamic Simulation computational fluid dynamics code

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Calculation of thermal response of ablator under arcjet flow condition

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JOURNAL OF THERMOPHYSICS AND HEAT TRANSFER 2007年第2期21卷 257-266页

作者： Suzuki, Toshiyuki Sakai, Takeharu Yamada, Tetsuya Nagoya Univ Dept Aerosp Engn Chikusa Ku Aichi 4648603 Japan Japan Aerosp Explorat Agcy Inst Space & Astronaut Sci Kanagawa 2298510 Japan

An integrated computational method is developed to calculate thermal response of ablator under an arcjet flow condition. In the method, the arcjet freestream condition in the test section is evaluated by calculating the flows in the arcjet wind tunnel fully theoretically. The thermal response of the ablator is calculated by loosely coupling the shock layer computational fluid dynamics code and the 2-D version of ablation code using the arcjet freestream condition so evaluated. The method is applied to the heating tests conducted in the I MW arcjet wind tunnel for one operating condition. The influence of catalytic conditions of ablating surface and the effect of nitridation reaction and surface roughness on the thermal response of the ablator are investigated. Comparison of the temperature profile at the ablating surface between calculation and measurement suggests that the measured temperature profile can be reproduced with a low catalytic efficiency of the surface. It is found that the nitridation reaction increase the surface temperature moderately, and that the effect of the roughness on the surface were small for the present operating condition.

关键词： Thermal Response Freestream Conditions Wind Tunnels Ablative Materials Shock Layers Surface Roughness computational Methods computational fluid dynamics code Pyrolysis Stagnation Region

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