风沙条件下颗粒对翼型流动分离的影响

运用延迟脱体涡模拟(delayed detached eddy simulation,DDES)技术对NREL S809三维翼型在洁净空气环境中和在不同直径颗粒环境下进行了数值模拟,由此预测了风沙环境下颗粒对翼型绕流分离的影响.研究结果表明:当攻角为8°时,DDES捕捉到了翼型吸力面的涡脱落现象,并且颗粒的加入显著地改变了翼型吸力面的涡脱规律,使得尾涡范围扩大、耗散更快,然而随着颗粒直径的增大,尾涡也逐渐恢复到接近洁净空气时的状态;当攻角较小(6°)时,翼型表面没有发生流动分离,颗粒的加入对流场的影响很小;当攻角较大(12°)时,颗粒对翼型绕流的影响也很小;不同攻角下颗粒对翼型升力系数有不同程度的影响.分析不同攻角下颗粒对翼型表面流动分离的影响规律表明:S809翼型绕流情况受颗粒影响最严重的攻角在7°~10°.

The effect of particles on the separation flow around airfoil in dusty environment

A delayed detached eddy simulation method is employed for the numerical simulation of flows around NREL S809 3D airfoil in clean air and various dusty environment with particles of different diameters. The effect of particle on the flow separation of airfoil was studied. It is shown that at an attacking angle of 8°, DDES has demonstrated the eddy shedding on the suction surface of the airfoil, and addition of particles significantly changes the regularity of eddy shedding on the suction surface of the airfoil, thus enlarging the range of the rear eddy and dissipating it faster. However, with the increase of particle diameter, the tail eddy gradually returns to the state closer to that of clean air. When the attacking angle is less than 6°, there is no flow separation on the surface of the airfoil, and the particles have little effect on the flow region. When the attacking angle is greater than 12°, the particles have even more little effect on the flow around the airfoil. Particles at different attacking angles have different effects on lift factor of the wing. The analysis of the effect of particles on the flow separation on the airfoil surface at different attacking angles shows that the attacking angle most affected seriously by particles is between 7°to 10°.