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Journal of Zhejiang University-Science A(Applied Physics & Engineering) 2020年第9期21卷 761-769页

作者： Bin-xian SHEN Hong-peng LIU Wei-qiang LIU China Computational Aerodynamics Institute China Aerodynamics Research and Development CenterMianyang 621000China Science and Technology on Scramjet Laboratory College of Aerospace Science and EngineeringNational University of Defense TechnologyChangsha 410073China

Flying condition with angle of attack is inevitable in a hypersonic vehicle,and it may influence the thermal protection system(TPS)performance of opposing jet and its combinations.A 3D Navier–Stokes equation and shear stress transfer(SST)k-ωmodel with compressible correction are employed to simulate the angle of attack characteristics of a blunt body with opposing jet and platelet transpiration *** flowfield and heat flux transfer for angles of attack 0°,3°,6°with jet pressure ratio PR=0.1 and 0°,6°,12°with PR=0.2 are *** results show that the flowfield is no longer symmetrical with the effect of the angle of *** flowfield and heat transfer in windward and leeward performed *** recompression shock wave in windward is strengthened,which increases local temperature and strengthens heat *** opposing jet fails in thermal protection when the angle of attack reaches critical value;however,the critical angle of attack can be promoted by increasing ***,the transpiration gas can strengthen the cooling efficiency of windward,thereby,increasing the critical angle of attack.

关键词： Thermal protection Opposing jet Platelet transpiration angle of attack

Influence of angle of attack and Lateral Force between Wheel and Rail on Wear of Rail ——a Laboratory Study

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Journal of Modern Transportation 2000年第1期17卷 85-91页

作者：金雪岩王夏秋 School of Mechanical Engineering Southwest Jiaotong University Chengdu 610031 China

angle of attack and lateral force are two important parameters influencing wheel rail wear. This paper deals with the question of influences of the angle of attack and the lateral force on the wear of rail. A series of experiments are conducted on 1/4 JD 1 Wheel/Rail Tribology Simulation Facility. The angles of attack selected in the tests are 0°16′30″, 0°37′40″ and 1°0′0″ respectively. The lateral forces selected in the tests are 0.694 kN, 1.250 kN and 2.083 kN, respectively corresponding to the lateral forces of 25 kN, 45 kN and 75 kN measured in the field, with the aim of keeping the same ratio of L/V between laboratory and field conditions. It is found that the larger the angle of attack is, the more serious the wear of rail is. The relation of rail wear rate versus angle of attack is non linear, and the relation of rail wear rate versus lateral force is approximately linear. The influence of angle of attack is more serious than that of lateral force. For the tractive wheelset, the wear index involving linear and quadratic function terms of angle of attack has good agreement with the limited experimental data. Some conclusions are given.

关键词： angle of attack lateral force wheel and rail wear

Performance of wavecatcher intakes at angles of attack and sideslip

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Chinese Journal of Aeronautics 2021年第7期34卷 244-256页

作者： Fengyuan ZUO Sannu MO LDER Gang CHEN State Key Laboratory for Strength and Vibration of Mechanical Structures School of Aerospace EngineeringXi’an Jiaotong UniversityXi’an 710049China Ryerson University Toronto ON M5B 2K3Canada

A wavecatcher type scramjet intake,that reduces the Mach number number from 4 to 1.552,is used as the basis for a study of flow starting/unstarting as affected by freestream angles of attack and *** intake design is based on a morphed streamtube consisting of two conical flow streamlines using streamline tracing and osculating axisymmetric design *** flow and performance is modeled using the numerical CFD code and the k-e turbulence *** intake unstarts at a sideslip angle of 2,a positive angle of attack of 1.Both positive angle of attack and sideslip angle have an adverse effect on the startability of the MBus *** negative angles,the intake initially unstarts at5angle of attack,due to the thickened shear layer induced by the streamwise *** it re-starts at8angle of attack,mainly due to the expansion fan formed at the leading edge,causing the shock wave structures inside the intake to be reestablished.

关键词： angle of attack Sideslip angle Unstart Wavecatcher intake

An experimental study on the effects of friction modifiers on wheel-rail dynamic interactions with various angles of attack

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Railway Engineering Science 2022年第3期30卷 360-382页

作者： Zhen Yang Pan Zhang Jan Moraal Zili Li Section of Railway Engineering Delft University of TechnologyStevinweg 12628 CN DelftThe Netherlands

By modifying friction to the desired level,the application of friction modifiers(FMs)has been considered as a promising emerging tool in the railway engineering for increasing braking/traction force in poor adhesion conditions and mitigating wheel/rail interface deterioration,energy consumption,vibration and *** the effectiveness of FMs in wheel–rail dynamic interactions is crucial to their proper applications in practice,which has,however,not been well *** study experimentally investigates the effects of two types of top-of-rail FM,***-A and FM-B,and their application dosages on wheel–rail dynamic interactions with a range of angles of attack(AoAs)using an innovative well-controlled V-track test *** tested FMs have been used to provide intermediate friction for wear and noise *** effectiveness of the FMs is assessed in terms of the wheel–rail adhesion characteristics and friction rolling induced axle box acceleration(ABA).This study provides the following new insights into the study of FM:the applications of the tested FMs can both reduce the wheel–rail adhesion level and change the negative friction characteristic to positive;stick–slip can be generated in the V-Track and eliminated by FM-A but intensified by FM-B,depending on the dosage of the FMs applied;the negative friction characteristic is not a must for stick–slip;the increase in ABA with AoA is insignificant until stick–slip occurs and the ABA can thus be influenced by the applications of FM.

关键词： Friction modifier V-track test rig Adhesion Wheel–rail dynamic interaction angle of attack Axle box acceleration

Quantification of wing and body kinematics in connection to torque generation during damselfly yaw turn

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Science China(Physics,Mechanics & Astronomy) 2017年第1期60卷 32-41页

作者： Samane Zeyghami Ayodeji T. Bode-Oke HaiBo Dong Department of Mechanical and Aerospace Engineering University of Virginia Charlottesville 22903 USA

This study provides accurate measurements of the wing and body kinematics of three different species of damselflies in free yaw turn fights. The yaw turn is characterized by a short acceleration phase which is immediately followed by an elongated deceleration phase. Most of the heading change takes place during the latter stage of the flight. Our observations showed that yaw turns are executed via drastic rather than subtle changes in the kinematics of all four wings. The motion of the inner and outer wings were found to be strongly linked through their orientation as well as their velocities with the inner wings moving faster than the outer wings. By controlling the pitch angle and wing velocity, a damselfly adjusts the angle of attack. The wing angle of attack exerted the strongest influence on the yaw torque, followed by the flapping and deviation velocities of the wings. Moreover, no evidence of active generation of counter torque was found in the flight data implying that deceleration and stopping of the maneuver is dominated by passive damping. The systematic analysis carried out on the free flight data advances our understanding of the mechanisms by which these insects achieve their observed maneuverability. In addition, the inspiration drawn from this study can be employed in the design of low frequency flapping wing micro air vehicles （MAV＇s）.

关键词： damselfly yaw turn angle of attack low flapping frequency wing kinematics flapping flight dynamics

Optimization of projectile state and trajectory of reentry body considering attainment of carrying aircraft

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Journal of Systems Engineering and Electronics 2017年第1期28卷 137-144页

作者： Changsheng Gao Chunwang Jiang Wuxing Jing School of Astronautics Harbin Institute of TechnologyHarbin 150001China

As an improvement of traditional maximum range trajectory optimization, both the projectile state and control sequence of reentry body are optimized to achieve the maximum range. To ensure the optimal projectile state is in the reachable domain of the carrying aircraft, the climb of the carrying aircraft and the flight of reentry body are optimized as a whole based on the hp-adaptive pseudospectral method. Meanwhile, the path constraints, control constraints and initial/terminal states constraints are considered in the optimization as well. In face of the fact that the range of the optimal control solution resulted from the pseudospectral method may be unsmooth, virtual control variables (second derivatives of the angle of attack and bank angle) are proposed in the optimization, while the angle of attack and bank angle are treated as the virtual state variables to guarantee the smoothness of the optimal control solution. The validity of the virtual control variables in smoothing the optimal control solution is verified by simulation, and the optimality of the resulting projectile state and control sequence for reaching the maximum range is confirmed using the indirect approach. © 1990-2011 Beijing Institute of Aerospace Information.

关键词： Aerodynamics angle of attack Optimal control systems Projectiles

The Role of Elytra in Beetle Flight: Ⅰ.Generation of Quasi-Static Aerodynamic Forces

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Journal of Bionic Engineering 2010年第4期7卷 354-363页

作者： Patar Ebenezer Sitorus Hoon Cheol Park Doyoung Byun Nam Seo Goo Cheol Heui Han National Research Laboratory for Biomimetics and Intelligent Microsystems Konkuk University Department of Advanced Technology Fusion Konkuk University Department of Aerospace Information System Engineering Konkuk University Department of Aeronautical and Mechanical Design Chungju National University

We conducted a comprehensive study to investigate the aerodynamic characteristics and force generation of the elytra of abeetle,Allomyrina *** analysis included wind tunnel experiments and three-dimensional computational fluiddynamics simulations using ANSYS-CFX *** first approach was a quasi-static study that considered the effect ofinduced flapping flow due to the flapping motion of the fore-wings (elytra) at a frequency of around 30 Hz to 40 *** dihedralangle was varied to represent flapping motion during the upstroke and *** found that an elytron producespositive lift at 0° geometric angle of attack,negative lift during the upstroke,and always produces drag during both the upstrokeand *** also found that the lift coefficient of an elytron does not drop even at a very high geometric angle of *** a beetle with a body weight of 5 g,based on the quasi-static method,the fore-wings (elytra) can produce lift of less than 1%of its body weight.

关键词： elytra angle of attack dihedral angle CFD wind tunnel test

Parameter study on lateral moments of banked wings in ground effect

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Chinese Journal of Aeronautics 2022年第3期35卷 53-61页

作者： Jingfeng XIE Lei SONG Jun HUANG Jingcheng FU School of Aeronautics Science and Engineering Beihang UniversityBeijing 100083China

Ground effect dramatically improves the performance of the Wing-in-Ground(WIG)vehicles near the ***,making coordinate turnings in ground effect zone may raise complexity in flight *** angle of attack(AOA)and height are believed to be important *** find the impact of these factors,three straight rectangular wings with different aspect ratios are simulated via CFD *** results show that in normal situations,the rolling moment tends to level the wing but less effective with the decreasing AOA and changes its direction when the AOA is less than a height dependent *** yaw moment exhibits complex behavior because two different effects generate oppose *** rolling moment coefficient is more influenced by the ground if a wing has larger Aspect Ratio(AR)and works at low to medium *** yawing coefficient is always more influenced if the wing has larger AR regardless *** findings can provide basic guidance for the design of control system and enable aircraft designers to reshape the crafts to avoid or utilize this effect.

关键词： angle of attack CFD Ground effect Lateral moments

Study of the Flow Mechanism of Wind Turbine Blades in the Yawed Condition

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Energy Engineering 2022年第4期119卷 1379-1392页

作者： Shuang Zhao Xijun Li Jianwen Wang College of Energy and Power Engineering Inner Mongolia University of TechnologyHohhot010051China Key Laboratory ofWind Energy and Solar Energy Technology Ministry of EducationHohhot010051China Key Laboratory of Wind and Solar Energy Utilization andOptimization in Inner Mongolia Autonomous Region Hohhot010051China Beijing Jingneng International Integrated Smart Energy Co. Ltd.Beijing100073China

The computational fluid dynamics method was used to simulate the flow field around a wind turbine at the yaw angles of 0°,15°,30°,and 45°.The angle of attack and the relative velocity of the spanwise sections of the blade were extracted with the reference points *** analyzing the pressure distribution and the flow characteristics of the blade surface,the flow mechanism of the blade surface in the yawed condition was *** results showed that the variations of the angle of attack and the relative velocity were related to the azimuth angle and the radius in the yawed *** larger the yaw angle was,the larger the variation *** pressure distribution in the spanwise sections was affected by both the angle of attack and the relative *** angle of attack was more influential than the relative *** the same yaw angle,when the angle of attack decreased,the c_(p)∼x/c curve shrunk inward and the lift force *** larger the yaw angle was,the more obvious the shrink *** effect of the yaw on the blade root region was higher than its effect on the blade tip region.

关键词： Flow characteristic angle of attack relative velocity pressure coefficient flow separation

Effects of Aeroelastic Modes on the dynamics of a Flexible Hypersonic Vehicle

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Effects of Aeroelastic Modes on the dynamics of a Flexible H...