The Effect of Humidity in a Mixture on Combustion : 2nd Report, The Effect on Combustion Period and Ignition Delay

Abstract

The Humidity in a mixture make delay times (Flame propagation delay : τdp, Total ignition delay : τt = τdfτdp) and total combustion period (τpmax) long. τdf was determined by the record of the ion current, τdp and τpmax were determined by the indicated pressure diagram in the constant volume combustion chamber. the results are as follows : 1) The ignition delay time takes the minimum value around φ =1.15. 2) τdf andτt time increased according to the increases of the concentration of dilution gases, because the adiabatic flmae temperature decreased due to the increases of the heat capacity. But dilution gases have little effect on flame nucleus formation delay. 3) The relation between τt time and the reciprocal of the laminer burning velocity is almost linear. 4) The larger the propagation length, the more was rate of changeτdf, τdp, τt, τpmax by dilution gases addition ratio.