Investigations on the Flamelet Inner Structure of Turbulent Premixed Flames

Abstract

Planar Rayleigh scattering measurements were used to investigate the inner structure of flamelets in premixed turbulent Bunsen flames. Measurements were performed in a high pressure chamber, where pressure is varied from 0.3 to 0.9 MPa. Two lean equivalence ratios (0.6 and 0.7) of methane/air mixtures were studied. Local information regarding the thickness and the local curvature of the flamelets were obtained. It is observed that an increase of the equivalence ratio induces a decrease of the mean local flamelet thickness. When pressure is increased from 0.3 to 0.9 MPa, the mean flamelet thickness does not decrease as for laminar case. The different external phenomena (turbulence and stretch (curvature and strain rate)) which could explain this trend are investigated.

Keywords:

• 2D Rayleigh scattering
• High pressure
• Local flamelet thickness
• Turbulent combustion

This work has been supported by the Centre National de la Recherche Scientifique, the region Centre and the European commission [AFTUR project (Alternative Fuels for industrial Gas Turbines), Contract No: CEE ENVK5-CT-2002-00662]. FH was supported by a grant from the CNRS and the Conseil Regional Centre.