Analysis of High Amplitude Acoustic Pressure Field Dynamics in a LOX/H2 rocket combustor

Abstract

High frequency combustion instabilities present a serious problem for liquid propellant rocket engines. These interactions between combustion chamber acoustics and variations of the heat release rate are difficult to predict, because the underlying coupling mechanisms are still not fully understood. For this reason self-excited combustion instabilities are investigated with a cryogenic research combustor at DLR Lampoldshausen. In order to get a better understanding of the coupling mechanisms the acoustic pressure field inside the combustion chamber needs to be described precisely. Due to the highly turbulent nature of the processes in a rocket combustor it can be expected that also the acoustic pressure field shows some variation during unstable combustion. The framework of this report new methods with high time resolution were applied to experimental data to analyze the dynamics of the pressure field for different types of instability. The results reveal that the applied methods give further insight into the excited pressure field and may help to identify the coupling mechanisms in the future.