Experimental observations of turbulent flame propagation effected by flame acceleration in the end gas of closed combustion chamber

Abstract

In present study, a new designed constant volume combustion bomb (CVCB) equipped with an orifice plate and visualized by high speed schlieren photography has been employed to study the turbulent flame propagation effected by flame acceleration in the end gas region. The orifice plate is employed to achieve flame acceleration and obtain different turbulent flames at different equivalence ratios. We investigate the flame propagation speed, the formation mechanism of compression front, the influence of flame acceleration on the end-gas as well as the flame structure changes. The results show that the laminar flame can be accelerated and transferred to a wrinkled turbulent flame through the orifice plate significantly and there forms a clear compression front ahead of the turbulent flame. The flame propagation speed without orifice plate shows the trend of initial increase and consequence decrease in the confined space. Moreover, the turbulent flame propagation speed shows the significantly different trend and demonstrates the “M” shape evolution including the self-acceleration, unstable and deceleration process. Finally, the evolution of turbulent flame in the end gas of the confined chamber was described in detail with three stages: compression front formation, flame front distortion and reverse propagation.