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

Abstract

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 numerical modal analysis of 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 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 flame response allowed addressing the question, whether the coupling of acoustics to combustion is via pressure or velocity sensitive processes.