Non-Linear Combustion Stability Prediction of Solid Rocket Motors

"Solid rocket motors are subject to combustion stability problemswhen the interior combustion processes interact with thecombustion chamber's acoustic modes, resulting in large pressureamplitude fluctuations. While the initial excitation process canbe predicted using linear analysis, the instability often entersa "limit-cycle", in which the maximum pressure amplitude levelsoff. This limit-cycle amplitude may only be predicted using non-linear analysis. It will be helpful for SRM designers to know ifa predicted instability will be detrimental or if the amplitudeis small enough to be ignored. The current 1-D stabilityprediction code (SSP) only performs the linear analysis. InPhase I of this SBIR, SEA examined the current non-linearcombustion stability theories and mathematical approaches. Notonly has SEA determined that the non-linear approach may beincorporated into the SPP/SSP code set, but SEA has alsoimplemented a 1-D nonlinear model and linked it to the output ofSPP/SSP. Testing of this model and implementation of furthermodels will be conducted in Phase II.BENEFITS: This research will result in an innovative design tool to predict combustion instability amplitudes of an unstable solid rocket motor during the design phase. This new tool will take advantage of themulti-dimensional stability analysis code currently being implemented. This product will bridge the gap between university (MURI) research and the solid rocket mot