天体物理学与航空航天技术

Modulated Thermoacoustic Singularities on Lifted Premixed Flames

Abstract

Sayantan Saha and Vinayak Malhotra

Efficient propulsion development is an area of major interest in space industry. Chemical propulsion-oriented rockets and space systems are well known to encounter acoustic instabilities. The modified heat fluxes, owing to wall temperature, reaction rates and non-linear heat transfer are observed. The thermoacoustic instabilities significantly result in reduced combustion efficiency leading to uncontrolled rocket engine performance, serious hazards to systems, assisted testing facilities, enormous loss of resources and every year substantial amount of money is being spent to prevent them. Appreciable work had been carried out in the past leading to a progressive stand however, the complexity of the problem has prevented a comprehensive solution. Present work attempts to fundamentally understand the mechanisms governing the thermoacoustic combustion in rocket engines using a simplified experimental setup comprising of a butane cylinder and an impinging acoustic source. The RL-10 engine generates a noise of 180 Db at its base. Systematic studies are carried out for varying fuel flow rates, acoustic levels and observations are made on the flames. The work is expected to yield a good physical insight into the development of acoustic devices that could effectively enhance combustion efficiency leading to safer missions and better fire safety.