The Visualization of Separated Flow over Slender Bodies at High Angles of Attack.

A new idea of the mechanism of the asymmetric separated flow is proposed based on the visualization of the separated flow over slender bodies of revolution at high angles of attack.Laser Light Sheet method is used in studying the detailed structure of the vortices in cross-sectional flow while a slide projector is used as a light source in visualizing the global flow pattern.It is found that the shear layer does not be rolled uniformally into a large scale single vortex but splits several times, each time accompanied with the formation of a new small scale vortex.Thus formed small scale vortices merge together to form a strong large scale vortex.The asymmetry in the vortex mergence and vortex breakdown position on the two sides of the body is found to be the cause of the global asymmetric separated flow.1.