MODELING THE ACOUSTIC BEHAVIOR OF A LIQUID ROCKET COMBUSTION CHAMBER AT ROOM AND OPERATIONAL CONDITIONS
Carlos dAndrade Souto1; Rogério Pirk1; Tiago Barbosa de Araújo2; Daniel Soares de Almeida2
1 IAE/AIE; 2 IAE/APE
doi:10.20906/CPS/COB-2015-1022
Resumo
Combustion instabilities occur when a great amount of energy is concentrated in one or more frequencies, generating pressure peaks much stronger than the background combustion noise. Liquid rocket engines can be affected by low and high frequency instabilities. The latter is related to the interaction of chamber acoustics with combustion process or with propellant injection flow oscillations. Combustion instabilities had been present in the development of liquid rocket engines since the infancy of this technology in the World War II. It can affect the rocket's propulsion system performance even resulting in catastrophic failure and still remains a major design concern. Some researchers pointed out that the combustion does not affect severely the acoustic behavior of a combustion chamber but its acoustic eigenfrequencies (at room temperature) are multiplied by a constant dependent of the operational temperature. In this work the eigenfrequencies of some acoustic modes of a liquid rocket chamber are calculated for room and operational conditions by using analytical methods and the finite element method. A harmonic response analysis is also performed.
Palavras-chave: combustion instabilities; acoustics; finite elements