Mitigation of Combustion Instability of Solid Rocket Motors by Modifying the Chemical Composition

The compositional parameters influencing the acoustics-combustion interaction towards mitigating the combustion instability for a solid rocket motor is discussed in this paper. Full scale static tests with motor-A with composition, comp-1, motor-B with comp-1 and motor-B with comp-2 were conducted. While motor-A with comp-1 had shown tolerable pressure oscillations, the same composition had shown unacceptable pressure and thrust oscillations in motor-B. Comp-1 was modified to comp-2. Then comp-2 was used in motor-B which mitigated the pressure and thrust oscillations. The results revealed that the pressure fluctuations were reduced from 1.35×10 5 Pa to 2×10 3 Pa and the thrust fluctuations were reduced from 0.7×10 4 N to 400 N. Solid rocket motors experience combustion instability when the acoustic pressure fluctuations couples with the mass flux fluctuations. Mitigating such pressure and thrust oscillations is a herculean task and in this work an engineering approach is adopted with the available prior knowledge and basic understandings about the ingredients. This is useful for a quick-fix for the rocket motor programme and it purely depends on trial-and-error and though success rate is sometimes low, it is worth pursuing as systematic approaches are yet to mature.