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Impact of Blade-Flapping Vibration on aerodynamic characteristics of Wind Turbines under Yaw Conditions

Energy Engineering 2024年第8期121卷 2213-2229页

作者： Shaokun Liu Zhiying Gao Rina Su Mengmeng Yan Jianwen Wang College of Energy and Power Engineering Inner Mongolia University of TechnologyHohhot010051China Key Laboratory of Wind and Solar Energy Utilization Technology Ministry of EducationHohhot010051China

Although the aerodynamic loading of wind turbine blades under various conditions has been widely studied,the radial distribution of load along the blade under various yaw conditions and with blade flapping phenomena is poorly *** study aims to investigate the effects of second-order flapwise vibration on the mean and fluctuation characteristics of the torque and axial thrust of wind turbines under yaw conditions using computational fluid dynamics(CFD).In the CFD model,the blades are segmented radially to comprehensively analyze the distribution patterns of torque,axial load,and tangential *** following results are obtained.(i)After applying flapwise vibration,the torque and axial thrust of wind turbines decrease in relation to those of the rigid model,with significantly increased fluctuations.(ii)Flapwise vibration causes the blades to reciprocate along the axial direction,altering the local angle of attack and velocity of the blades relative to the incoming wind *** results in the contraction of the torque region from a circular shape to a complex“gear”shape,which is accompanied by evident oscillations.(iii)Compared to the tangential load,the axial load on the blades is more sensitive to flapwise vibration although both exhibit significantly enhanced *** study not only reveals the impact of flapwise vibration on wind turbine blade performance,including the reduction of torque and axial thrust and increased operational fluctuations,but also clarifies the radial distribution patterns of blade aerodynamic characteristics,which is of great significance for optimizing wind turbine blade design and reducing fatigue risks.

关键词： Wind turbine CFD numerical simulation aerodynamic characteristics yaw flapping vibration

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Effect of low operating temperature on the aerodynamic characteristics of a high-speed train

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Journal of Zhejiang University-Science A(Applied Physics & Engineering) 2023年第3期24卷 284-298页

作者： Xiujuan MIAO Guangjun GAO Jiabin WANG Yan ZHANG Wenfei SHANG College of Automotive and Mechanical Engineering Changsha University of Science&TechnologyChangsha 410076China Key Laboratory of Traffic Safety on Track of Ministry of Education School of Traffic&Transportation EngineeringCentral South UniversityChangsha 410075China Joint International Research Laboratory of Key Technology for Rail Traffic Safety Central South UniversityChangsha 410075China National&Local Joint Engineering Research Center of Safety Technology for Rail Vehicle Changsha 410075China

In this study,an improved delayed detached eddy simulation(IDDES)method based on the shear-stress transport(SST)k-ωturbulence model has been used to investigate the underbody flow characteristics of a high-speed train operating at lower temperatures with Reynolds number Re=1.85×10^(6).The accuracy of the numerical method has been validated by wind tunnel *** aerodynamic drag of the train,pressure distribution on the surface of the train,the flow around the vehicle,and the wake flow are compared for four temperature values:+15℃,0℃,−15℃,and−30℃.It was found that lower operating t emperatures significantly increased the aerodynamic drag force of the *** drag overall at low temperatures increased by 5.3%(0℃),11.0%(−15℃),and 17.4%(−30℃),respectively,relative to the drag at+15℃.In addition,the low temperature e nhances the positive and negative pressures around and on the surface of the car body,raising the peak positive and negative pressure values in areas susceptible to impingement flow and to rapid changes in flow *** range of train-induced winds around the car body is significantly reduced,the distribution area of vorticity moves backwards,and the airflow velocity in the bogie cavity is significantly *** the same time,the temperature causes a significant velocity reduction in the wake *** can be seen that the temperature reduction can seriously disturb the normal operation of the train while increasing the aerodynamic drag and energy consumption,and significantly interfering with the airflow characteristics around the car body.

关键词： High-speed train(HST) Low temperature aerodynamic characteristics Cold region Improved delayed detached eddy simulation(IDDES)

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aerodynamic characteristics,Power Requirements and Camber Effects of the Pitching-Down Flapping Hovering

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Journal of Bionic Engineering 2009年第2期6卷 120-134页

作者： Peng Bai,Er-jie Cui,Hui-ling ZhanChina Academy of Aerospace aerodynamics,Beijing 100074,P.R.China China Academy of Aerospace aerodynamics Beijing P. R. China

The pitching-down flapping is a new type of bionic flapping,which was invented by the author based on previous studies on the aerodynamic mechanisms of fruit fly(pitching-up)*** motivation of this invention is to improve the aerodynamic characteristics of flapping Micro Air Vehicles(MAVs).In this paper the pitching-down flapping is briefly *** major works include:(1)Computing the power requirements of pitching-down flapping in three modes(advanced,symmetrical, delayed),which were compared with those of pitching-up flapping;(2)Investigating the effects of translational acceleration time,Δτ_t,and rotational time,Δτ_r,at the end of a stroke,and the angle of attack,α,in the middle of a stroke on the aerodynamic characteristics in symmetrical mode;(3)Investigating the effect of camber on pitching-down *** the above works, conclusions can be drawn that:(1)Compared with the pitching-up flapping,the pitching-down flapping can greatly reduce the time-averaged power requirements;(2)The increase in Δτt and the decrease in Δτ_r can increase both the lift and drag coefficients, but the time-averaged ratio of lift to drag changes a *** α has significant effect on the aerodynamic characteristics of the pitching-down flapping;(3)The positive camber can effectively increase the lift coefficient and the ratio of lift to drag.

关键词： aerodynamic characteristics flapping wing power requirements camber effect pitching-down-flapping MAVs

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Numerical study of aerodynamic characteristics of FSW aircraft with different wing positions under supersonic condition

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Chinese Journal of Aeronautics 2016年第4期29卷 914-923页

作者： Lei Juanmian Zhao Shuai Wang Suozhu School of Aerospace Engineering Beijing Institute of Technology

This paper investigates the influence of forward-swept wing (FSW) positions on the aerodynamic characteristics of aircraft under supersonic condition (Ma = 1.5). The numerical method based on Reynolds-averaged Navier-Stokes (RANS) equations, Spalart-Allmaras (S-A) turbulence model and implicit algorithm is utilized to simulate the flow field of the aircraft. The aerodynamic parameters and flow field structures of the horizontal tail and the whole aircraft are presented. The results demonstrate that the spanwise flow of FSW flows from the wingtip to the wing root, generating an upper wing surface vortex and a trailing edge vortex nearby the wing root. The vortexes generated by FSW have a strong downwash effect on the tail. The lower the vertical position of FSW, the stronger the downwash effect on tail. Therefore, the effective angle of attack of tail becomes smaller. In addition, the lift coefficient, drag coefficient and lift-drag ratio of tail decrease, and the center of pressure of tail moves backward gradually. For the whole aircraft, the lower the vertical position of FSW, the smaller lift, drag and center of pressure coefficients of aircraft. The closer the FSW moves towards tail, the bigger pitching moment and center of pressure coefficients of the whole aircraft, but the lift and drag characteristics of the horizontal tail and the whole aircraft are basically unchanged. The results have potential application for the design of new concept aircraft. (C) 2016 Chinese Society of Aeronautics and Astronautics. Production and hosting by Elsevier Ltd.

关键词： aerodynamic characteristics Downwash effect Forward-swept wing Numerical simulation Supersonic flow

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Numerical and experimental study of the aerodynamic characteristics around two-dimensional terrain with different slope angles

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Frontiers of Earth Science 2019年第4期13卷 705-720页

作者： Pingzhi FANG Deqian ZHENG Liang LI Wenyong MA Shengming TANG Shanghai Typhoon Institute of China Meteorological Administration Shanghai 200030China School of Civil Engineering and Architecture Henan University of TechnologyZhengzhou 450001China Wind Engineering Research Center Shijiazhuang Tiedao UniversityShijiazhuang 050043China

Complicated terrain was considered and simplified as two-dimensional(2D)terrain in a dynamical downscaling model and a parametric wind field model for typhoons developed by the Shanghai Typhoon *** 2D terrain was further modeled as uphill and downhill segments with various slope angles relative to the incoming *** wind speed ratios and pressure characteristics around the 2D terrain were numerically and experimentally investigated in this *** characteristics of the 2D terrain with a limitedlength upper surface were first investigated in the wind tunnel with sheared incoming *** corresponding numerical investigation was also conducted by using the commercial computational fluid dynamics code FLUENT with the realizable k-ε turbulence *** efforts were made to maintain the inflow boundary conditions throughout the computational *** characteristics were then investigated for the ideal 2D terrain with an unlimited-length upper surface by using a numerical method with uniform incoming *** of the different terrain models and incoming flows from the above studies show that the wind pressure coefficients and the wind speed ratios are both affected by the slope angle.A negative peak value of the wind pressure coefficients exists at the escarpment point,where flow separation occurs,for the uphill and downhill terrain models with slope angles of 40°and 30°,***,the streamwise wind speed ratios at the points above the escarpment point for the uphill terrain model increase with increasing slope angle,reach their peak values at the slope angle of a=40°and decrease when the slope angle increases *** the downhill terrain model,similar trends exist at the points above the escarpment point with the exception that the critical slope angle is a=30°.

关键词： numerical simulation wind tunnel test aerodynamic characteristics critical slope angle

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Research on the aerodynamic characteristics of Leading Edge and Bulge of Ram-Air Parafoil Based on CFD

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World Journal of Engineering and Technology 2023年第4期11卷 989-999页

作者： Lei Ding Lingrui Chen Yalei Bai Huimin Yao Chuanyu Gao College of Aerospace Engineering Nanjing University of Aeronautics and Astronautics Nanjing China

This study focuses on the aerodynamic characteristics and flow mechanism of three different configurations of ram-air parafoil with open/closed air inlet and bulges. Firstly, we designed a special parafoil configuration for this study. Then we used numerical simulation to obtain the aerodynamic data of three parafoils at different angles of attack, and studied the influence of the bulge and the leading edge open/closed inlet on the aerodynamic performance of the ram-air parafoil. Finally, we study the flow mechanism of the ram-air parafoil through the pressure distribution and flow field. The results of the study show that compared with the aerodynamic parameters of the parafoil without bulges, the optimal angle of attack of the two parafoils with bulges is increased by 4?, the maximum lift to drag ratio of the parafoil with closed leading edge is reduced by about 4.3% and the optimal angle of attack is reduced by about 2?. The maximum lift to drag ratio of the parafoil with open leading edge is reduced by about 23.6% and the stalling angle of attack is reduced by about 4?. The pressure on the surface of a ram-air parafoil with open leading edge inlet is the highest. .

关键词： Ram-Air Parafoil Numerical Simulation aerodynamic characteristics Flow Mechanism

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Calculation of aerodynamic characteristics of Hypersonic Vehicles Based on the Surface Element Method

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Advances in Aerospace Science and Technology 2022年第2期7卷 112-122页

作者： Tianqiang Huang Guoyi He Qi Wang Nanchang Hangkong University Nanchang China

A program for calculating the aerodynamic properties of hypersonic vehicles based on the surface element method was developed using the general-purpose programming language C++. The calculated values of lift coefficients, drag coefficients, and surface pressure coefficients are discussed with the results of wind tunnel experiments using the HL-20 lift body and the NASA hypersonic aircraft STS Columbia OV-102 as research subjects. Finally, the results of the experimental and wind tunnel studies of the aerodynamic characteristics of the HL-20 lift body at an altitude of 65 km and Mach numbers of 6 and 10 Ma are discussed. The maximum error in the aerodynamic characteristics at 6 Ma does not exceed 3%, consistent with the results. The maximum error at 10 Ma occurs in the 11° - 14° angle of attack and does not exceed 10%, which is still within the error tolerance. The STS results for NASA’s hypersonic aircraft were also tested using this procedure. Experimental aerodynamic data for the Colombian OV-102 aircraft. The results show that the program takes only 10 minutes to calculate the results, with no more than 2% error from the wind tunnel experimental results.

关键词： Surface Element Method Hypersonic Vehicle C++ aerodynamic characteristics Engineering Calculations

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Numerical Study on aerodynamic characteristics of Ducted Fan Aircraft

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Journal of Beijing Institute of Technology 2010年第1期19卷 19-24页

作者：范宁军徐嘉杨继伟 School of Mechatronical Engineering Beijing Institute of Technology

Based on investigations into the flow field of ducted fan aircrafts,structural parameters of duct are quantified.A three-dimensional model is established for numerical simulation,and adaptive Cartesian grid is used to mesh the model in order to improve calculation speed and solution ***-dimensional Navier-Stokes equations are brought in to analyze different duct *** of simulation results leads to several conclusions in duct aerodynamics to help design ducted fan aircrafts.

关键词： ducted fan aircraft aerodynamic characteristics structural parameter numerical calculation

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Experimental Study of Effects of Tail Wings on Submunition aerodynamic characteristics

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Journal of Beijing Institute of Technology 2004年第3期13卷 331-335页

作者：王海福李向荣 State Key Laboratory for the Prevention and Control of Explosion Disasters Beijing Institute of Technology Beijing100081 China

Aimed at the needs of deceleration of submunitions dispensed from the ballistic missile, wind tunnel tests were performed on the submunitions with different tail wing sizes at the Mach number range from 0.7 to 3.0 and the angle of attack range from 0° to 14°. Experimental data about the variance of aerodynamic coefficients with the Mach number and angle of attack were obtained systemically. The effects of the tail wing sizes on the drag coefficients and the center of pressure coefficients were discussed. Analyzed results show the arc tail wings designed are beneficial to both the deceleration effect and static stability. These results are significant to the tail wing design and its applications to the submunitions deceleration..

关键词： wind tunnel tests aerodynamic characteristics deceleration static stability

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Wind Tunnel Experimental Investigation on the aerodynamic characteristics of the Multifin Rockets and Missiles

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Journal of Beijing Institute of Technology 2005年第3期14卷 293-296页

作者：郝璐吴甲生 School of Mechatronics Engineering Beijing Institute of Technology Beijing100081 China School

The transonic-supersonic wind tunnel experiment on the aerodynamics of the rockets and missiles that have four, six, eight flat or wrap-around fins is introduced. The experimental results show, while M∞〈2.0, with the increase of the fins＇number, the derivative of lift coefficient is increasing, the pressure center is shifting backwards, and the longitudinal static stability is augmenting. On the contrary, while the Mach number exceeds a certain supersonic value, the aerodynamic effectiveness of the eight-fin missiles would be lower than that of the six-fin missiles. For the low speed short-range missiles, by adopting six, eight or ten flat fins configuration, the lift effectiveness can be greatly increased, the pressure center can be shifted backwards, the static and dynamic stability can be obviously enhanced. For the high speed long-range large rockets and missiles launched from multi-tube launcher, the configuration adopting more than six fins can not be useful for increasing the stability but would make the rolling rate instable during the flight.

关键词： multifin wrap-around fins flat fins aerodynamic characteristics wind tunnel experiment

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