EFFECTS OF SWIRL AND AIR-FUEL RATIO ON PREMIXED COMBUSTION IN A CLOSED VESSEL

Experiments were performed to reveal 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 ST, the burning zone thickness δT of turbulent flames and the laminar burning velocity SL were measured under various conditions. The main results obtained are as follows: (1) both ST and SL depend on the equivalence ratio and achieve maximum values under the condition of slightly rich mixture; (2) the value of δT increases with the increase of ST/SL and there is a correlation between δT and ST/SL; (3) the ratio of the main stage of burn duration to the total burn duration decreases and the ratio of the early stage increases with the increase of turbulence intensity, and these are almost independent of the equivalence ratio.