旋翼桨-涡干扰气动特性计算及参数影响研究

建立了一个适用于旋翼桨-涡干扰(BVI)气动特性分析的数值方法。在该方法中,控制方程采用惯性坐标系下的非定常Euler方程,以适合于分析BVI流场的特点;为便于前飞流场分区求解和信息传递,使用了嵌套网格方法;对于流场中涡线的模拟,建立了一种适用于有限体积格式的涡引入方法——广义网格速度法,以简化计算。应用上述方法对旋翼BVI流场进行了计算,并与可得到的试验数据进行对比,验证了方法的有效性。通过对比桨叶弦向位置压强的变化得出,在旋翼BVI过程中,气动载荷主要来自桨叶10%弦长内的前缘部分的压强突变。文中还进一步分析了涡强、干扰距离和干扰角度对BVI气动特性的影响。本文的BVI数值计算表明:当涡接近桨叶前缘时,升力达到最大;而涡位于后缘位置时,诱导速度改变桨叶环量分布,破坏了后缘的库塔条件,但随着涡的远离,桨叶表面环量开始重构。

Numerical Calculation and Parametric Study of Aerodynamics of Rotor Blade-vortex Interaction

A numerical method for modeling the aerodynamics of blade vortex interaction (BVI) is developed which adopts the unsteady Euler equations in inertial coordinate systems to capture the features of the rotor BVI flow and uses the overset grid technique to realize multi zone solution and information exchange in forward flight. To incorporate the effect of the vortex in the solution, an effective approach, called the “generalized grid velocity approach” is presented to simplify computation. Numerical examples on the rotor BVI flow field are performed by this method, and a comparison of the calculated results with available experimental data demonstrats its validity. By comparing the pressure variations for various chord locations, it is shown that the BVI loading is mainly caused by the high rate of change of the pressure within 10% of the leading edge. Furthermore, additional calculations are carried out to analyze the effect of vortex strength, miss distance and interaction angle on the aerodynamic characteristics of BVI. The present investigation indicates that lift reaches its maximum when the vortex position is slightly upstream of the leading edge of the airfoil, and that the circulation on the blade surface suitable for the trailing edge Kutta condition is altered by the induced velocity of the vortex passing the trailing edge, but it starts to be re established as the vortex moves farther away.