Effect of the Constrictive Area Ratio on the Rocket Exhaust Flow-Field in the Launcher
Aerospace engineering rept.
TEXAS UNIV AT AUSTIN DEPT OF AEROSPACE ENGINEERING AND ENGINEERING MECHANICS
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There are a variety of military rockets which are launched from variable-area launch tubes. The change in cross section allows the rocket to be initially constrained after ignition, while momentum is gained. The flow of the high temperature and high pressure rocket exhaust gas is of practical interest in the structural design of the launcher. Of special concern is the possible generation of unbalanced forces on the rocket by exhaust gases which are deflected upstream i.e., blow-by flow and which could influence the trajectory, once the rocket is released from its constraints. Flow in the so- called non-tipoff launch tubes is particularly complex since these tubes have diameter changes so that the rocket flies free of any tube support for a short distance as it emerges from the tube. The objectives of the experimental program included the determination of the parameters which govern the generation of a strong shock wave which may occur when the exhaust flow impinges on the wall. Of special interest was the determination of the ratio of the radius of the aft tube to the radius of forward tube for which the flow was no longer choked by the constriction.