Effects of Pressure on Laminar and Turbulent Burning Velocities of Ethanol Premixed Flames

Abstract

Spherically propagating laminar and turbulent flames at elevated pressures in a large volume chamber were studied for ethanol / air mixtures. The properties of the ethanol flame at elevated pressures, especially the burning velocity and the effects of the flame stretch acting upon it are quit important for the modeling of combustion in internal combustion engines. Experiments were carried out in the wide range of the equivalence ratio from 0.8 to 1.4 at two turbulence intensities of 0.80 and 1.59m/s varying the initial pressure from 0.10 to 0.50MPa. The unstretched laminar burning velocity decreased with increasing initial pressure. The ratio of turbulent burning velocity to unstretched laminar burning velocity increased with increasing the turbulence Karlovitz number. This ratio of the burning velocities was large for rich flames. Thermo-diffusive effects might be more influential to rich ethanol flames because of their small Lewis number. The ratio of turbulent to laminar burning velocity was also found to increase with increasing initial pressure.