Effects of swirl turbulent flow field and stratified concentration field on combustion of fuel-air mixture in a constant volume vessel (1st report, combustion characteristics of stratified mixture)

A swirling flow was produced in a vessel by tangentially charging fuel-air mixture or air. Rich fuel concentration was formed near the center of the vessel by fuel injection. Mixture was ignited at the center of the vessel. Various swirling flow field and fuel concentration field were made by changing the mean equivalence ratio in the vessel, the timing of charging mixture and fuel injection. The mean equivalence ratio in the vessel was changed from 0.20 to 0.84. Appropriate mixture stratification enabled initial combustion to be faster than that of homogeneous mixture. Under the lean condition, the combustion efficiency was lower and flame could not propagate in the lean mixture region near the wall as the homogeneity of the mixture became larger. In the case of the slowest swirling condition, initial combustion and initial flame propagation became slower due to rich mixture near the center of the chamber.