Experimental Study of NG-Air Mixtures at Initially Laminar Conditions

Laminar burning velocity is one of the most important thermo chemical properties of any combustible mixture. it relates to some variables such as type of fuel, mixture composition, its temperature and pressure. Laminar burning velocity plays a vital role in evaluating turbulent burning velocity. Evaluating laminar burning velocity at different temperatures and pressures of NG-air mixtures using experimental data and finding out a related correlation are more important. To meet the aims, a significant set of experimental pressure-time data were recorded for combustion of NG-air stoichiometric mixtures at the ranges of initial temperature of 300 to 360K and initial pressure of 3 to 7.5 bar; then they defined as input to a simulator of two zone thermodynamic combustion model and burning velocities in terms of bomb pressure during combustion period were calculated. Error analysis showed that the estimation was faced with large error at the early stage and low error at the other stages of combustion. The selected function used to correlate the laminar burning velocity versus temperature and pressure was in the form of l l 0 0 0 u u T T P P. The least square method was utilized to determine ul0, and over more than 5000 data of burning velocity and their values were found to be 22.55(cm/s), 1.68 and -0.24, respectively, with average deviation of 2.92%.