Thermoacoustic Instabilities in Solid Rocket Motors

This work describes an unreported instability in so lid rocket motors found out by numerical simulations. A detailed numerical study s hows that this instability is thermoacoustic and results from a coupling between acoustic velocity and aluminum combustion heat release. The computations suggest that the driving parameter is the thickness of the aluminum combustion zone. The influence of the aluminum combustion model has been undertaken but appeared to be insignificant as long as the combustion thickness remains in a certain range. A theoretical assessment of this instability is also obtained using a linear stability analysis. Finally , the effect of the scale has also been addressed and showed that this thermoacoustic coupling is liable to happen at small scale too.