Non-Linear Combustion Stability Prediction of Solid Rocket Motors

Period of Performance: 12/18/2002 - 12/18/2004


Phase 2 SBIR

Recipient Firm

Software & Engineering Assoc., Inc.
1802 N. Carson Street, Suite 200
Carson City, NV 89701
Principal Investigator


Solid rocket motors are subject to combustion stability problems when the interior combustion processes interact with the combustion chamber's acoustic modes, resulting in large pressure amplitude fluctuations. While the initial excitation process can be predicted using linear analysis, the instability often enters a "limit-cycle", in which the maximum pressure amplitude levels off. This limit-cycle amplitude may only be predicted using non- linear analysis. It will be helpful for SRM designers to know if a predicted instability will be detrimental or if the amplitude is small enough to be ignored. The current 1-D stability prediction code (SSP) only performs the linear analysis. In Phase I of this SBIR, SEA examined the current non-linear combustion stability theories and mathematical approaches. Not only has SEA determined that the non-linear approach may be incorporated into the SPP/SSP code set, but SEA has also implemented a 1-D nonlinear model and linked it to the output of SPP/SSP. Testing of this model and implementation of further models 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 the multi-dimensional stability analysis code currently being implemented. This product will bridge the gap between university (MURI) research and the solid rocket motor community.