Aerodynamics of Low Reynolds Number Plunging Airfoil under Gusty Environment
Aerodynamics of Low Reynolds Number Plunging Airfoil under Gusty Environment
复制标题
阵风环境下低雷诺数下降翼型的气动特性
DOI：
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发表时间：
2007
期刊：
影响因子：
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通讯作者：
W. Shyy
中科院分区：
文献类型：
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作者：
Y. Lian;W. Shyy
在一定的幅值和频率组合下，纵倾翼型既能产生升力又能产生推力。出于对微型飞行器的兴趣，我们利用NavierStokes方程求解器来研究扑翼的空气动力学。研究了纵倾和纵摇振幅、频率和Strouhal数对系统运动的影响。对于零几何攻角、弦雷诺数为2×10 4的对称倾翻翼型NACA 0 0 12，在相同的倾翻频率下，根据倾翻幅度的不同，既可以产生阻力，也可以产生推力。在所考虑的倾翻幅度（从0.0125c到0.075c）下，流动历史比运动攻角对确定升力的影响更大。当产生阻力时，粘性力在总阻力中占主导地位，且影响随纵倾幅值的增大而减小。对于一个机翼经历组合的暴跌和俯仰运动，推力和输入功率增加与斯特劳哈尔数（在0.03至0.5的范围内）。对于所研究的情况，推力是由升力引起的，它近似地遵循运动攻角的曲线。前缘涡向下游移动并与后缘涡相互作用。本文还研究了阵风对静止翼型和扑动翼型的影响。在试验参数范围内，定常翼型升力与速度同相，阻力略有异相。对于扑翼，升力和阻力都不与速度同相。标称值CD =单位跨度阻力系数CL =单位跨度升力系数CP =输入功率系数CP，平均值=时均输入功率系数CT =推力系数CT，平均值=时均推力系数c =弦长
It is known that plunging airfoil can produce both lift and thrust with certain combination of plunging amplitude and frequency. Motivated by our interest in micro air vehicles (MAVs), we utilize a NavierStokes equation solver to investigate the aerodynamics of a flapping airfoil. The roles of the plunging and pitching amplitude and frequency, and Strouhal number are studied. For a symmetric plunging airfoil NACA0012 at zero geometric angle of attack and chord Reynolds number of 2×10 4 , at the same plunging frequency, it can produce either drag or thrust depending on the plunging amplitude. At the considered plunging amplitude (from 0.0125c to 0.075c), the flow history has more influence than the kinematic angle of attack to determine the lift. When drag is produced, the viscous force dominates the total drag with decreasing influence as the plunging amplitude increases. For an airfoil experiencing combined plunge and pitch motion, both thrust and input power increase with the Strouhal number (within the range of 0.03 to 0.5). For the case studied, the thrust is induced by the lift, which approximately follows the curve of the kinematic angle of attack. Leading edge vortex moves downstream and interacts with the trailing edge vortex. We also study the impact of gust on stationary airfoil and flapping airfoil. Within the range of the parameters tested, for stationary airfoil the lift is in phase with the velocity but the drag is slightly out of phase. For flapping airfoil, neither lift nor drag is in phase with the velocity. Nomenclature CD =Drag coefficient per unit span CL =Lift coefficient per unit span CP =input power coefficient CP,mean =time-averaged input power coefficient CT =thrust coefficient CT,mean =time-averaged thrust coefficient c =Chord length