Combustion instability of solid rocket motor with complicated grain shape

Combustion instability or oscillation combustion which occurred in three high capacity solid rocket motors using high energy composite propellant with finocyl grain shape was discussed in this paper. The reasons of the acoustic combustion instability were also discussed. Three engineering methods that can help to eliminate combustion instability in solid rocket motor chamber with complicated grain shape were proposed and discussed. In this study, the results show that combustion instability mainly depends on propellant grain shape, nozzle structure that can damp the acoustic energy and mass generation rate of combustion gas. Static test results of the redesigned rocket motors indicate that the proposed methods can significantly eliminate the combustion instability and improve the motor internal ballistic performance.