A Study of Secondary Injection of Gases into a Supersonic Flow

Citation

Spaid, Frank William (1964) A Study of Secondary Injection of Gases into a Supersonic Flow. Dissertation (Ph.D.), California Institute of Technology. doi:10.7907/T76G-2R21. https://resolver.caltech.edu/CaltechETD:etd-10312002-082315

Abstract

The flow field around the injection port for secondary injection of a gas normal to a supersonic stream has been studied in a series of wind tunnel experiments. The experiments were conducted at free-stream Mach numbers of 1.38 to 4.54. Gaseous nitrogen, argon, and helium were injected through a circular hole or a transverse slot with sonic flow at the injection orifice. Data are presented which include static pressure distributions on the wall in the region of the injector, shock shapes, and injectant mass fraction, total pressure, and velocity profiles downstream of the injector. A scale parameter has been calculated, based on a simple, inviscid model of the flow field. This scale parameter gives a good general correlation of the data. Use of this scale parameter allows the prediction of a simple scaling law for the normal forces on a wall produced by secondary injection. For the case of injection through a slot, this scaling law has been compared with experimental results reported by other workers. This comparison indicates that further work will be necessary to clarify the effect of free-stream Mach number on the flow field. For the case of injection through a hole, the force scaling law is in approximate agreement with existing rocket motor test results.

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