Investigation of the Combustion Chamber Acoustics and its Interaction with LOX/H₂-Spray Flames

Abstract

The acoustics of combustion chambers is investigated experimentally in cold flow and hot fire tests. The performance of absorber elements is analyzed in respect to their effect on combustion chamber eigenfrequencies as well as to their damping characteristics. It is shown that predictions of 2D- and 3D-modal analysis of the chamber acoustics are in very good agreement with measurements. In hot fire tests a burning LOX/H₂ spray is acoustically excited with a siren wheel and the combustion response is recorded with dynamic pressure sensors and by high speed visualization of the spray and the flame. Although no combustion instability could be observed, analyzing the temporal and spatial distribution of the flame response allowed addressing the question, whether the coupling of acoustics to combustion is via pressure or velocity sensitive processes.