圆柱-平板角区湍流流动控制的风洞试验研究

Experimental study on control of the cylinder-flat-plate turbulent junction flow

角区流动中马蹄涡系的存在通常会造成不良影响。对圆柱-平板角区流动,在圆柱上游放置一倾斜的小圆棒能够改变角区流动结构。利用油流法和平板表面压力测量方法探讨了湍流流态下不同的小圆棒对平板表面的摩擦力线和压力分布的影响。油流实验揭示了倾斜棒能够改变角区的三维分离,新的分离线由倾斜棒和圆柱共同作用引起;倾斜棒对角区的作用可归类为两种不同的物理现象;倾斜棒能够引起圆柱侧面的分离线向下游发生极大的迁移,导致圆柱底部区域尾迹变窄。平板表面压力测量实验揭示附加的倾斜棒能够极大地改变压力分布情况,角区的逆压梯度相应减小;由此,逆压梯度引起的三维分离必然被削弱。

The horseshoe vortex system in the juncture region is usually a disadvantageous factor to the flow.An inclined rod upstream of the cylinder can modify the flow structure in the circular cylinder flat plate junction region.The effects of the rods,which were located upstream of the primary vortex,on the skin friction line and the distribution of the pressure were expounded for the turbulent junction flows,with oil-flow and manometry.The results from the oil-flow experiments show that an inclined rod can alter the 3-D separation,and the new separation line is induced by the combination of the cylinder and the rod.The action can be classified into two categories.The separation lines shift downstream greatly,so the wake from the cylinder near the plate becomes narrows.The pressure distribution is modified by the inclined rod,the adverse pressure gradient decreases,so the separation is weakened.