Impact of chamber volume on the measurement of laminar burning velocity using constant volume spherical flame method

Abstract

The objective of this work was to investigate the impact of chamber volume on the measured value of laminar burning velocity using constant volume spherical flame method. Experimental unsteady pressure-time data of stoichiometric methane air mixture recorded in spherical chambers of different volumes ranging from 0.5 to 20 L was obtained from different research groups. All the collected data in the reduced normalized pressure range of 0.25–0.5 were processed with a two zone thermodynamic model. One dimensional unsteady spherical flame model at constant volume in COSILAB along with GRI-Mech3.0 reaction mechanism was used for predicting laminar burning velocity. The values of stretched burning velocity at elevated pressures and temperatures differed with chamber volume due to flame stretch effects. The extrapolated stretched laminar burning velocity at 1 bar and 300 K using power law found to be independent of spherical chamber volume. From the present comparison of stretched burning velocity data between 0.5 and 20 L, it was found that the constant volume spherical flame method may deliver laminar burning velocity with less stretch effects if a spherical combustion chamber of 4.4 L range was used.