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 : τ_dp, Total ignition delay : τ_t = τ_dfτ_dp) and total combustion period (τ_pmax) long. τ_df was determined by the record of the ion current, τ_dp and τ_pmax 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) τ_df andτ_t 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 τ_t time and the reciprocal of the laminer burning velocity is almost linear. 4) The larger the propagation length, the more was rate of changeτ_df, τ_dp, τ_t, τ_pmax by dilution gases addition ratio.