Study of Combustion Oscillation Mechanism and Flame Image Processing

Abstract

In the pursuit of low emissions and large propulsion in the fields of civil and military aviation, combustion oscillation has been attracting increasing attention. In the present study, the coupling mechanisms of combustion oscillations in a model combustor are investigated. The oscillation characteristics and dynamic flame structure are studied for better comprehending their intrinsic nature. Current surveys show that inlet parameters, nozzle mounting positions, and fuel supply have important effects on combustion oscillation. The coupling and decoupling boundary composed of the factors mentioned above divides combustion into stable, transition, and instable regions. The effects of the operating conditions on combustion present a certain complexity in terms of studying oscillations. For the model combustor, periodic velocity fluctuation with large amplitudes is regarded as “bridge” that links pressure wave and heat release fluctuation, and it further leads to coupling processing. The acoustic simulation results suggest that the oscillation frequency is in accordance with the acoustic resonance frequency of the exhaust pipes. Finally, to investigate the internal spatiotemporal fluctuation mechanisms of the flame structure, the proper orthogonal decomposition method is used to decompose the dynamic flame structure. The phase relationship between the pressure wave and heat release fluctuation is investigated herein as well.