The effect of swirl on the combustion of a homogeneous mixture in a closed vessel. 3rd report. The effect of equivalence ratio on the combustion.

Abstract

Experiments were performed to make clear the effects of the equivalence ratio and the turbulence characteristics on the combustion of a propane-air homogeneous mixture. A turbulent flame propagating nearly axisymmetrically in the swirling flow was produced in a disc-type combustion chamber. The burning velocity Sr, the burning zone thickness δr of turbulent flames and the laminar burning velocity SL, were measured under various conditions. The main results obtained are as follows: (1) Both Sr and SL depend on the equivalence ratio and have a maximum value under the condition of slightly rich mixture, (2) the value of δr increases with the increase of Sr/SL, (3) the ratio of the burn duration of main combustion stage to the total burn duration decreases and the ratio of the early combustion stage increases with the increase of turbulence intensity, but those are almost independent of the equivalence ratio.