Effects of Turbulence on Combustion of Homogeneous Mixture of Fuel and Air in Closed Vessel

Abstract

The effects of turbulence on the flame propagation in closed vessel were investigated by analyzing the high speed schlieren motion pictures of flames and the pressure changes. Turbulent conditions were prepared by moving a perforated plate quickly once for each experiment, and the characteristics of turbulence were measured by a laser Doppler velocimeter. The main results are as follows: (1) The flame propagation speed and the rate of pressure rise increase with an increasing intensity of turbulence. The volume enveloped by turbulent flame, however, is larger than that by laminar flame at the same mass fraction burned. This fact suggests that turbulent flame has some mass fraction burned. This fact suggests that turbulent flame has some "burning zone", which includes unburned gas cloud. (2) The thickness of burning zone δ_T and the turbulent burning velocity S_T increase with an increasing intensity of turbulence having higher frequency than f₀, where f₀=(S_T/δ_T)/2.