Dynamic Response of a Dual-Manifold Injector Rocket Engine to Throttling

Abstract

The capability of a dual-manifold injector rocket engine scheme for deep throttling under extremely fuel-rich condition was demonstrated experimentally. The dynamic response of the rocket engine to throttling was analyzed as well. Under the extremely fuel-rich condition, the response of chamber pressure is sensitive to oxygen adjusting but insensitive to fuel adjusting. Response delay appears at the end of throttling, for both oxygen-adjusting cases and fuel-adjusting cases. The response delay mainly comes from the supply system for oxygen adjusting, whereas the response delay mainly results from the combustion process for fuel adjusting. The antiregulation, which means the chamber pressure variation is opposite to the throttling direction, occurs at the beginning of throttling. It can only be triggered by fuel adjusting, not by oxygen adjusting. It is found that fuel adjusting contributes to the antiregulation, whereas oxygen adjusting suppresses the antiregulation. Furthermore, the effects of oxygen adjusting and fuel adjusting on the antiregulation are positively related with their adjusting rate. The slow evaporation of liquid fuel under extremely fuel-rich condition is identified strongly with the response delay and the antiregulation. First, the evaporation time of liquid fuel is the main reason for response delay after the throttling process is terminated. Second, it is the interval between large amounts of heat absorption and large amounts of vapors released during the evaporation process of droplets that finally results in the antiregulation.