Secondary injection thrust vector control(SITVC) of rockets has been in use for sometime. This paper presents an experimental and analytical study on disturbances produced by secondary injection and on an estimation of control forces produced by SITVC. SITVC is done by gas injection or by liquid injection. The control force producing mechanism of gas injection TVC is a little different from that of liquid injection TVC. Most part of the present study is devoted to investigating the disturbances produced by under－expanding gas injection TVC and to presenting an analytical method for estimating control forces of gas injection. Disturbances such as under－expanding gas injection flow, complicated flowfield ahead of injection flow, and leading shock wave in a conical supersonic flowfield are investigated by using two-dimensional cold and dry air flow and by using conical lens method. An analytical model to predict disturbances induced by secondary gas injection is presented. The comparison of the analysis with the induced disturbed flow is shown in good correlation. Based on the analysis, an estimation of produced control forces by gas injection is tried. The measured control forces produced by secondary gas injection thrust vector control(GITVC) tests, conducted on solid propellant rockets, are compared with the estimated control forces. Liquid injection thrust vector control(LITVC) also was conducted and the produced control forces were measured by multi components thrusts measuring stand. The regions contributing to the generation of control force of LITVC are discussed by means of an analytical model to predict liquid injectant trajectory. The difference between gas injection and liquid injection is discussed.
An Investigation of Secondary Injection Thrust Vector Control
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