A comparison of time and frequency domain descriptions of high frequency acoustics in rocket engines with focus on dome coupling

Abstract

A comparison of time and frequency domain descriptions for acoustic considerations in rocket engines with focus on the acoustic coupling behaviour between the combustion chamber and the oxidizer dome is presented. To simplify pre- and post-processing and to allow for simple validation, a cold-case setup without combustion is used. The comparisons show that both frequency and time domain based descriptions are suitable to predict the acoustic behaviour in typical rocket engine configurations including especially the damping capabilities of the nozzle and face plate. Advantages and disadvantages of both frameworks are discussed showing that in case of linear wave propagation, frequency based computations are fast and provide excellent accuracy. The time domain code is favourable if wave propagation becomes relevantly non-linear. On the other hand, general conclusions concerning the relevance of the dome coupling are drawn from the results, showing that damping is greatly influenced by the coupling.