旋翼翼型动态失速流场特性PIV试验研究及L-B模型修正

为测量翼型动态失速的非定常涡流场特性，采用3D-PIV 技术，对典型直升机旋翼翼型SC1095 的动态失速流场特性进行测量，发现涡在不同位置处的输运速度不同:位于翼型表面的涡的无量纲速度为0.39，位于尾迹区的涡的无量纲速度为0.55. 利用前缘涡输运速度变化这一特征，改进了经典的翼型动态失速利什曼-贝多斯（Leishman-Beddoes，L-B）模型，将该模型中固定的涡时间常数修正为可以随涡位置变化的时变函数，修正后的模型计算得到翼型法向力峰值相对原L-B 模型提升5%，力矩系数负峰值相对原L-B 模型提升13%，与试验值相比更加吻合，表明修正后的翼型动态失速模型更好地体现了翼型前缘涡的物理特征. 

PIV EXPERIMENTS ON FLOWFIELD CHARACTERISTICS OF ROTOR AIRFOIL DYNAMIC STALL AND MODIFICATIONS OF L-B MODEL

To investigate the flowfiled characteristics of airfoil dynamic stall, the advanced 3D-PIV technology was employed to measure the dynamic stall flowfield of helicopter rotor airfoil SC1095. It was found that the leading edge vortex convective velocity changed with the location of vortex. The dimensionless vortex velocity was 0.39 when the vortex was moving on airfoil surface, and was 0.55 at airfoil wake zone. Based on the different leading-edge vortex convective velocities, classical Leishman-Beddoes model was then modified, in which the vortex time constant in classical model is replaced by a time varying function. Comparing with the classical model, the peak of airfoil normal force coefficient calculated by the modified model was increased about 5%, and the negative peak of airfoil moment coefficient was promoted about 13%; both of these had better agreements with the experimental data, and it was demonstrated that the modified model gave a more reasonable physical meaning of airfoil leading edge vortex.