Some solid propellants have an intermediate self-quenching pressure range (ISQPR), which is around several MPa. When the propellants are burned in a motor under a pressure near the lower limit of the ISQPR, the motor exhibits oscillatory combustion. In a previous study, we attempted combustion interruption to pressurize the motor chamber from the oscillatory combustion state into the ISQPR. After pressurization by inert gas, water spray sometimes quenched the burning surface, but sometimes failed. We should clarify how the timing of water spray in the pressure oscillation aspect affects the interruption. In the present study, our objectives were to control the pressure oscillation aspect and to examine the relationship between the water spray timing in the controlled pressure oscillation and the interruption. An experiment revealed that the oscillatory aspect was controllable by adjusting the direction of inert gas injection. The timing of water spray had little effect, but holding the pressure around the higher limit of the ISQPR was effective for interruption.
solid rocket motor, propellant, rocket propulsion, combustion