Towards the Effects of Initial Grain Temperature and Erosive Burning on the Solid Propellant Combustion

Abstract

On the basis of an improved mathematical model it was explored how the derived nonlinear pressure coupling response function, depending on pressure and frequency, behaves at extreme initial grain temperatures. This is accomplished by extending the existing model QSHOD (Α Β) to incorporate the effects of nonlinearity. Pressure - frequency analysis of nonlinear combustion response function at the pressure coupling is a relevant input of this paper and provides useful data on the occurrence of the combustion instability in the case of unsteady DB homogeneous solid propellant burning with and without erosion. A study concerning the combustion stability prediction based on the classical linear stability theory was also included in our paper. The model incorporates unsteady rotational sources and sinks in the acoustic energy assessment and thus a more accurate acoustic instability evaluation can be achieved. This method involves the computing of minimum 11 growth rate terms that arise in the dynamics of an oscillating complex flow. Finally, the paper gives an overview of some experimental results on combustion instabilities and pressure oscillations in DB solid propellant rocket motors (SPRM-01, 02 and 03). Some particular pressure-time traces, at extreme grain initial temperatures, with significant perturbed pressure signal were recorded and FFT analysed.

Keywords

• combustion instability
• Double-Base homogeneous solid propellant
• unsteady burning rate
• acoustic growth rate terms
• pressure coupled response function