EXPERIMENTAL-STUDY ON LIQUID QUENCH OF SOLID ROCKET MOTOR

This article proposes a physical model for liquid quench of solid rocket motor and presents the results of experimental study. It is found that there is a critical value of injection pressure drop during liquid quench of solid rocket motor. The critical value of injection pressure drop increases with propellant energy (Q(f)). The additive selected appropriately added in liquid is able to reduce significantly the liquid quantity required (LQR) Ws, for extinction of solid rocket motor. LQR reduced by the addition of 0.5% CE by weight in water are about 35 and 25% for double base propellant and nonmetalized polyurethane-ammonium perchlorate composite propellant, respectively. LQR is mainly dependent upon the propellant energy, i.e., it increases with increasing propellant energy. For pure water, Ws is-proportional-to 0.1Q(f) and for water + 0.5% CE, Ws is-proportional-to 0.76Q(f). The variation of LQR with the chamber pressure is related to pressure exponent of propellant (n). If n > 0, it increases with increasing chamber pressure; and if n < 0, it decreases with increasing chamber pressure. With the injection pressure drop increasing, LQR decreases and the depressurization rate of solid rocket motor increases, respectively. The experimental results and the analysis indicate that the theoretical study on liquid quench of solid rocket motor should include the coupling effects of transient burning of propellant, heat transfer of liquid jet impinged on burning surface, evaporation of liquid droplets, and internal ballistics of rocket motor.