Acoustic resonance upon propellant combustion

The effect of errors in initial data necessary to predict the stability conditions of operation of a solid-propellant rocket motor (SRM) on the accuracy of predicting the boundary of stability is discussed. It is shown that small variations of the characteristics of the steady regime of propellant combustion lead to large changes in the unsteady response because of the resonance dependence of the response of unsteady combustion to the frequency of harmonically varying pressure. By the example of the simplest problem of acoustic instability of propulsion, the relationship between the measurement errors in initial data and the accuracy of stability prediction is studied. It is emphasized that it is almost impossible to predict the stability of a motor under certain actual conditions of its operation at the existing level of measurement accuracy of the steady parameters of propellant combustion.