Nonlinear Combustion Stability Prediction of Solid Rocket Motors

Period of Performance: 11/02/2002 - 05/02/2002


Phase 1 SBIR

Recipient Firm

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


Software & Engineering Associates, Inc., proposes to develop a new tool to analyze solid rocket motor combustion stability which will predict for an unstable motor the combustion chamber's maximum over-pressurization. When a rocket motor experiences combustion instability, it often does not experience a catastrophic failure, but a temporary amplitude limited pressure fluctuation. If the magnitude of the fluctuation can be predicted, one can then determine if it is sufficiently low as to be ignored, or if it will damage the payload or cause unacceptable flight variations. The current stability analysis code examines each of the combustion chamber's acoustic modes separately. As such, it cannot model the transfer of energy between unstable and stable acoustic modes, transfers which can act to dampen the unstable mode, resulting in an amplitude limited pressure fluctuation (limit cycle). A new non-linear analysis technique developed at Cal Tech compares a given unstable acoustic mode with the other modes in the system, and from that predicts the maximum amplitude of the over-pressurization. The focus of this Phase I SBIR will be to identify the algorithms and inputs required to implement a non-linear stability analysis into the current solid rocket motor combustion stability code. 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.