Starting Transient Flow Phenomena in Inert Simulators of Solid Rocket Motors with Divergent Ports

Abstract

The basic idea behind a solid rocket motor (SRM) is simple but its design is a complex technological problem requiring expertise in diverse subdisciplines to address all of the physics involved. The design optimization of high-performance rockets is more complex when the mission demands dual thrust. The motivation for the present study emanates from the desire to explain the phenomena or mechanism(s) responsible for the high ignition peak pressure (pressure peak), pressure-rise rate, instabilities, and pressure oscillations often observed during the static tests and the actual flights of certain class of high-performance SRMs with nonuniform ports [1–9]. In the SRM industry many dual-thrust motors (DTMs) are known to have experienced abnormal high ignition peak pressure often on the order of 5 times the steady state value [6]. Various measures were taken to eliminate the peak pressure, but none of the conventional remedies seemed to help. Nevertheless, through the empirical techniques increasing the port area of the motor has been proposed as one of the remedies for reducing the unusual ignition peak of the DTM. Although such a remedy could negate the unacceptable peak pressure, it has affected the high-performance nature of the motor. Hence the elimination of the unusual ignition peak and the pressure-rise rate without sacrificing the basic grain configuration or the volume loading became a meaningful objective for further studies.