The effect of initial pressure and temperature upon the laminar burning velocity and flame stability for propane-air mixtures

Adel M Salih*  and   Miqdam T Chaichan*

Assistant Prof., Machines and Equipment Engineering Dept., University of Technology, Baghdad, Iraq

Corresponding author email : miqdam1959@yahoo.com

Accepted 21 September 2014

Abstract

Laminar burning velocity is very important for both combustion modeling and kinetic scheme validation and improvement. Accurate experimental data are needed. To achieve this, a spherical flame with constant pressure method was chosen, since it allows high-pressure and high-temperature initial conditions. Considerations were established to link between stretched and unstretched velocities, where the stretch factor controls the burning velocity. Because of the lack of data for burning velocity of propane-air mixtures at elevated pressures and temperatures, and the importance of such data for the applications in engines and turbines as described previously, it is necessary to obtain data for these conditions. Results for higher initial pressures and temperatures have been obtained for a wide range of equivalence ratios. The laminar burning velocity of propane−air mixtures was measured using thermocouples technique. The experiments were carried out for a wide range of equivalence ratios from Ø= 0.5 to Ø= 1.5, mixture initial temperatures of 300 to 350 K, and mixture initial pressure from 0.5 to 1.5 bar. The detailed uncertainty analysis shows the accuracy of the present measurement within ±5%. The present measurements are successfully validated against existing experimental and computational results. The peak burning velocity was observed for slightly rich mixtures even at higher mixture temperatures. The burning velocity was observed to decrease with increasing initial pressure. Markstein Number increases with increasing with equivalence ratio increases from lean to rich mixtures. But it decreases with increasing initial temperature.

Keywords:  Initial pressure, Temperature, Laminar burning velocity, Flame stability for propane-air mixtures.