Liquid injection thrust vector control for hybrid rockets

Abstract

A liquid injection thrust vector control (LITVC) system which uses a hybrid rocket oxidizer as an injectant can be compactly integrated with hybrid rocket systems. In this research, the LITVC system for the hybrid rocket that uses 95 wt.% hydrogen peroxide and high-density polyethylene was designed, and the identical hydrogen peroxide was used as a liquid injectant. In the preliminary hot-fire test, the low LITVC performance was observed due to a low freestream Mach number near the injection location. To increase the flow Mach number, the chamber pressure was doubled, and the LITVC performance was investigated in terms of the injection location and injectant flow rate through a series of hot-fire tests. The test results suggested that the freestream Mach number and the static pressure of the injection point had a significant influence on the LITVC performance. As a result of increasing the chamber pressure, the side specific impulse was improved about 80 s. At X/L = 0.47, the LITVC system showed the highest performance among the injection locations. Moreover, it was visualized that the injectant flow path spread more under the higher injectant flow rate, and this radial spreading seemed to degrade the side specific impulse.