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Simulation of three-dimensional nonideal MHD flow at high magnetic Reynolds number

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中国科学：技术科学英文版 2010年第1期53卷 206-212页

作者： LU HaoYu1 & Lee ChunHian2 1 School of astronautics,Beihang university,beijing 100191,{3. 2 national laboratory for computational fluid dynamics,Beihang university,beijing 100191,{3. School of astronautics Beihang University Beijing China national laboratory for computational {3. dynamics Beihang University Beijing China

A conservative TVD scheme is adopted to solve the equations governing the three-dimensional flow of a nonideal compressible conducting fluid in a magnetic *** eight-wave equations for magnetohydrodynamics(MHD) are proved to be a non-strict hyperbolic system,therefore it is difficult to develop its *** developed a new set of equations which cannot be numerically simulated by conservative TVD scheme directly due to its non-conservative form.A conservative TVD scheme augmented with a new set of eigenvectors is proposed in the *** validate this scheme,1-D MHD shock tube,unsteady MHD Rayleigh problem and steady MHD Hartmann problem for different flow conditions are *** simulated results are in good agreement with the existing analytical *** this scheme can be used to effectively simulate high-conductivity fluids such as cosmic MHD problem and hypersonic MHD flow over a blunt body,etc.

关键词： magnetohydrodynamics(MHD) numerical simulation TVD MHD Rayleigh flow MHD Hartmann flow

Physical analysis and numerical simulation for the dynamic behaviour of vehicles in pitching oscillations or rocking motions

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Science china(Technological Sciences) 2007年第4期50卷 385-401页

作者： ZHANG HanXin1,2,3. ZHANG Zhao1,3. YUAN XianXu1,2, LIU Wei1, XIE YuFei1,2 & YE YouDa1,2 1 china Aerodynamics Research and Development Center, Mianyang 621000, china {3., beijing university of aeronautics and astronautics, beijing 100083. china 3.School of Aerospace, Tsinghua university, beijing 100084, china china Aerodynamics Research and Development Center Mianyan China national laboratory for computational {3. dynamics Beijing University of Aeronautics and Astronautics Beijing China School of Aerospace Tsinghua University Beijing China

Analytical methods of nonlinear dynamics and numerical simulations for the cou-pling equations of Navier-Stokes and flight mechanics are used to study the dynamic behaviour of pitching motions of reentry capsules with the variation of Mach number, and rocking motions of swept wings with the variation of angle of attack. Conditions under which the dynamic instability, Hopf bifurcation and saddle-node bifurcation occur are obtained. The node-saddle-node topological structure in the phase portrait, i.e. the state of bi-attractors (attracting basins) is described. The evolving process of dynamic behaviour and flow fields are given. The theories are compared with some numerical simulations conducted by the authors. Besides, some verifiable experi-mental results are cited. The agreement between them is very well.

关键词： physical analysis numerical simulation pitching oscillation rocking motion bifurcation

Effects of flexibility on aerodynamic performance of delta wings with different sweep angles

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Science china(Physics,Mechanics & Astronomy) 2010年第5期53卷 915-922页

作者： LIU Yang,ZUO LinXuan & WANG JinJun Institute of fluid Mechanics,beijing university of {3. and astronautics and fluid Mechanics Key laboratory,Ministry of Education,beijing 100191,china Institute of fluid Mechanics Beijing University of Aeronautics and Astronautics and Fluid Mechanics Key Laboratory Ministry of Education Beijing China

Force measurement and surface oil flow visualization experiments were conducted in a wind tunnel to investigate the effects of flexibility on aerodynamic performance of delta wings with different sweep *** experimental results indicate that the maximum lift coefficient is increased and the stall angle is delayed as the sweep angle increases for both rigid and flexible *** is also found that the maximum lift coefficients of the flexible wings with a sweep angle from 3.° to 50° are higher than those of the rigid *** increment of the maximum lift coefficient in particular achieves 3..9% compared with the case without lift enhancement for the 40° flexible delta ***,the surface oil flow visualization experiments show that the stall of the flexible wing of the moderate low sweep angle is accompanied by helical flow structure,while the vortex bursting appears on the corresponding rigid wing.

关键词： delta wing wing flexibility aerodynamics sweep angle

Study on flow behavior and structure over chined fuselage at high angle of attack

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Science china(Technological Sciences) 2010年第8期53卷 2057-2067页

作者： TIAN Wei,DENG XueYing ,WANG YanKui,FAN GuoLei&DONG Chao Ministry of Education Key laboratory of fluid Mechanics,beijing {3. of aeronautics and astronautics,beijing 100191,china Ministry of Education Key laboratory of fluid Mechanics Beijing University of Aeronautics and Astronautics Beijing China

A study of leeward vortex structure over chined fuselage and the effects of micro tip perturbation on its vortex flow have been carried out in wind tunnel experiments at Reynolds numbers from 1.26×105 to 5.04×105 with PIV and pressure measurement ***,the experiment results have proved that micro tip perturbation has no effects on the vortex flow and its aerodynamic characteristics over chined fuselage at high angle of attack,in which there are not any non-deterministic flow ***,the evolution of leeward vortex structure over chined fuselage along the axis of model can be divided into four flow regimes:linear conical developed regime,decay regime of leeward vortex intensity,asymmetric leeward vortex break down regime and completely break down *** a correlation between leeward vortex structure and sectional aerodynamic force was also revealed in the present ***,the experiment results show the behavior of leeward vortex core trajectories and zonal characteristics of leeward vortex structure with angles of ***,the experiment results of Reynolds number effect on the leeward vortex flow have further confirmed research conclusions from previous studies:the flows over chined fuselage at high angles of attack are insensitive to variation of Reynolds number,and there is a little effect on the secondary boundary layer separation and the suction peak induced by leeward vortex.

关键词： high angle of attack aerodynamics chined fuselage tip perturbation leeward vortex structure zonal characteristics

Unsteady aerodynamic modeling based on POD-observer method

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Science china(Technological Sciences) 2010年第8期53卷 2032-2037页

作者： YANG Chao,LIU XiaoYan &WU ZhiGang beijing university of aeronautics and astronautics,beijing 100191,china beijing university of aeronautics and {3. Beijing China

A new hybrid approach to constructing reduced-order models(ROM)of unsteady aerodynamics applicable to aeroelastic analysis is presented by using proper orthogonal decomposition(POD)in combination with observer *** modes are generated through POD by sampling observations of solutions derived from the full-order *** response in the POD training is projected onto the fluid modes to determine the time history of the modal *** resulting data are used to extract the Markov parameters of the low-dimensional model for modal amplitudes using a related deadbeat *** state-space realization is synthesized from the system's Markov parameters that are processed with the eigensystem realization *** POD-observer method is applied to a two-dimensional airfoil system in subsonic flow *** results predicted by the ROM are in general agreement with those from the full-order *** ROM obtained by the hybrid approach captures the essence of a fluid system and produces vast reduction in both degrees of freedom and {3. time relative to the full-order model.

关键词： aeroelasticity aerodynamic modeling proper orthogonal decomposition observer eigensystem realization algorithm

Flow structures in flat plate boundary layer induced by pulsed plasma actuator

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Science china(Technological Sciences) 2010年第4期53卷 2772-2782页

作者： ZHANG PanFeng1,2, LIU AiBing1 & WANG JinJun1,2 1Institute of fluid Mechanics, beijing university of aeronautics and astronautics, beijing 100191,{3. 2Key laboratory of fluid Mechanics, Ministry of Education, beijing 100191,{3. Institute of fluid Mechanics Beijing University of Aeronautics and Astronautics Beijing China Key laboratory of fluid Mechanics Ministry of Education Beijing China

The flow field in the flat plate boundary layer induced by the pulsed plasma actuator was simulated by solving the Navier-Stokes equations with a phenomenological DBD plasma model. The effects of actuation strength,wave form and frequency on the flow structures induced by the unsteady pulsed plasma actuator were investigated. The results indicated that a series of vortex pairs were formed in the boundary layer,and decayed in downstream convection following the exponential law. The strength of vortex pair was dominated by the effective plasma actuation strength,and the vortex streamwise spacing depended on the actuation frequency. If the duty cycle is not so large that interaction of adjacent vortex pairs can be negligible,then the actuation wave form has little influence on the vortex pair induced by the unsteady plasma actuator.

关键词： plasma actuator unsteady actuation boundary layer numerical simulation

An adaptive version of ghost-cell immersed boundary method for incompressible flows with complex stationary and moving boundaries

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Science china(Physics,Mechanics & Astronomy) 2010年第5期53卷 923-932页

作者： WANG Liang1 & WU ChuiJie2,3.1 School of Science,PLA university of Science and Technology,Nanjing 211101,china 2 State Key laboratory of Structural Analysis for Industrial Equipment,Dalian university of Technology,Dalian 116024,china 3.School of aeronautics and astronautics,Dalian university of Technology,Dalian 116024,china School of Science PLA University of Science and Technology Nanjing China State Key laboratory of Structural Analysis for Industrial Equipment Dalian University of Technology Dalian China School of aeronautics and astronautics Dalian University of Technology Dalian China

An adaptive version of immersed boundary method for simulating flows with complex stationary and moving boundaries is *** method employs a ghost-cell methodology which allows for a sharp representation of the immersed *** simplify the implementation of the methodology,a volume-of-fluid method is introduced to identify the immersed *** addition,the domain is spatially discretized using a tree-based discretization which is relatively simple to implement a fully flexible adaptive refinement ***,the methodology is validated by comparing it with numerical and experimental results on three cases:(1) the flow passing a circular cylinder at Re=40 and Re=100,(2) a periodic oscillation of a circular cylinder in fluid at rest and(3. the self-propelled fish-like swimming at Re=6400.

关键词： adaptive mesh refinement ghost-cell immersed boundary method moving boundaries

THE STUDY OF ENTROPY CORRECTION FUNCTION IN TVD SCHEMES

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THE STUDY OF ENTROPY CORRECTION FUNCTION IN TVD SCHEMES

Optimization design study of low-Reynolds-number high-lift airfoils for the high-efficiency propeller of low-dynamic vehicles in stratosphere

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作者： LU Ye WU Song Pingnational laboratory of computational {3. dynamics beijing university of aeronautics and astronautics beijing 100083.china

＜正＞ A modified form based on Yee’s velocity-dependent entropy correction function is proposed and some factors are considered in this form such as the subsonic region behind shock waves, the temperature-increasing section and the aspect ratio of grids. It can keep the flow parameters well when simulating the chemically reacting flows over complex three-dimension body and acquire the satisfactory flow characteristics.

关键词： hypersonic flows TVD scheme entropy correction function

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Science china(Technological Sciences) 2010年第10期53卷 2792-2807页

作者： MA Rong1, ZHONG BoWen2 & LIU PeiQing1 1 Key laboratory of fluid Mechanics, Ministry of Education, Institute of fluid Mechanics, School of Aeronautical Science and Engineering,{3., beijing 100191, china 2 Department of Aerospace Science, School of Engineering, Cranfield university, MK43.0AL, United Kingdom Key laboratory of fluid Mechanics Ministry of Education Institute of Fluid Mechanics School of Aeronautical Science and Engineering Beijing University of Aeronautics and Astronautics Beijing China Department of Aerospace Science School of Engineering Cranfield University Cranfield UK

Aerodynamic performance of low-Reynolds-number high-lift airfoil makes a great impact on designing a high-efficiency propeller for low-dynamic vehicles in stratosphere. At high altitude,low-Reynolds-number airfoils are supposed to have high lift-drag ratio or high endurance factor at cruising attack angle along with good stall characteristics. To design such a high-performance low-Reynolds-number high-lift airfoil,the paper established a hierarchical multi-objective optimization platform by combing direct search optimization algorithm EXTREM and airfoil flow field solver XFOIL to automatically and quickly calculate aerodynamic performance function of airfoil by computer. It provides an effective solution to multi-point design problem of low-speed low-Reynolds-number airfoil. It can be seen from the results of three typical optimization examples,the new airfoil E3.7_OPT2,FX63.13._OPT2 and S1223.OPT2 based on hot low-Reynolds-number high-lift airfoils (Eppler 3.7 airfoil,Wortmann FX63.13. airfoil and S1223.airfoil) can meet the optimization design requirements and have very good aerodynamic characteristics in both design state and non-design state. Thus,the applicability and effectiveness of hierarchical multi-objective optimization platform are verified.

关键词： multi-objective optimization low Reynolds number airfoil EXTREM hierarchical multi-objective optimization