低雷诺数下二维翼型绕流的流场特性分析

采用高精度有限差分格式,对低雷诺数下二维翼型绕流进行了直接数值模拟,计算了雷诺数为1.0×104,NACA0012翼型0°,4°以及10°攻角下的流场。计算结果表明:在0°和4°攻角条件下,翼型绕流尾迹区的统计特性相似,0°攻角下的统计量值具有很好的对称性;在距翼型尾缘0.3弦长以后的尾迹区,旋涡排列成类似涡街的结构,涡量的极值、压力的极小值都位于旋涡中心,沿着流向,涡量极值的绝对值逐渐减小,压力的极小值逐渐增大。10°攻角下,翼型上表面从前缘开始分离,尾迹区统计分析结果所得图象与0°和4°完全不同,数值上较后者结果大;在翼型尾缘处,涡量的卷吸,高压力区域的形成,是旋涡脱落的条件,正向和反向旋涡的交替脱落,形成了类似涡街的结构。 

The Analysis of Flow Around a 2-D Airfoil at Low Reynolds Number

Using high order finite difference scheme,a direct numerical simulation (DNS) of low Reynolds number flow around a NACA0012 airfoil was carried out.The Reynolds number based on chord is 1.0×10.4,the angles of attack are 0°,4° and 10°.The computation results indicate that the statistical traits of wake region are similar at angles of attack 0° and 4°.In the wake region distancing trailing edge 0.3 chord,ordered vortex streets exist,the extremum of vorticity and minimum of pressure are located in the center of vortices.Along the streamline,the absolute value of vorticity decreases gradually,while the minimum of pressure increase step by step.The statistical traits of wake region at angle of attack 10° are different from that at other two angles.The absorption of vorticity and formation of high pressure region are two conditions of vortices shedding.