An Exploratory Study of Open Wake Effects Upon the Pressure Distribution of a Hypersonic Body

摘要

High base pressures have resulted in the formation of separation regions on hypersonic bodies. To investigate this occurrence, air was injected against a small flat plate in the wake region of an axially symmetric ellipsoid, and the boundary layer was separated. The tests were conducted in a four-inch hypersonic wind tunnel at Mach numbers of 14 and 17. It was concluded that the effects from side mounted stings were the most probable cause of open wakes. It was necessary to increase the Reynolds number with increasing Mach number if an open wake was to be avoided. Two conditions of laminar boundary layer stability were encountered: One stability condition produced a free-interaction between boundary layer separation and reattachment, while the more stable condition always produced a strong interaction between them. It was noted that the model temperature necessary for the increased stability phase of a laminar boundary layer, decreased with increasing Mach number. The method of air injection used is a simple and effective means by which the boundary layer-shock wave interaction can be investigated along the length of a body. (Author)