Experiments were conducted with a counter-rotating, streamwise vortex pair embedded in flat plate boundary layers, in a low-turbulence wind tunnel, to understand the role of local separation on transition. Steady, streamwise vortices were generated downstream of gaps in spanwise-uniform, smooth hills (of height h) affixed to the plate, 175 mm from its leading edge. The flow between is directed away from the plate. At the four tunnel speeds 1.8–3.5 m/s considered, the Reynolds numbers based on displacement thickness at this location variedfrom 248 to 346. Small, medium and large gaps of 2, 4 and 8 mm, respectively, were set up; they were about a third to twice the boundary layer thickness (2/3 展开▼
机译：实验是在低湍流风洞中将逆向旋转的涡流对嵌入平板边界层中，以了解局部分离在过渡过程中的作用。在固定在距板前缘175 mm处的翼展均匀，光滑的山丘（高度为h）中，在缝隙的下游产生了稳定的沿流方向的涡流。之间的流动被引导远离板。在考虑四个隧道速度1.8-3.5 m / s时，基于位移厚度的雷诺数在该位置从248到346不等。分别设置了2、4和8 mm的小，中和大间隙。它们大约是边界层厚度的三分之一到两倍（2/3 展开▼
