On some properties of reattaching laminar and transitional high speed flows.

This paper is a review of some of the work done at the von Karman Institute over the past years on separated flows. Emphasis is given on a fundamental phenomenon developing in reattaching high speed flows. namely, spatially periodic patterns of counter-rotating streamwise vortices. Detailed surveys made with pitot-static tubes, hot wire probes, recovery temperature and heat transfer gages are presented. The effect of streamwise vortices on transit ion was studied using axisymmetric models on which the strength of vortices could be artificially controlled. For this purpose, a new criterion for transition detection was used. The effect of air and foreign gas injection in separated flow was studied and its application to suppressing local heat transfer peaks examined.