Laminar burning velocities and flame instabilities of 2,5-dimethylfuran–air mixtures at elevated pressures

Abstract

An experimental investigation on laminar burning velocities and onset of flame instabilities on spherically expanding flames in 2,5-dimethylfuran–air mixtures at elevated pressures was conducted over a wide range of equivalence ratios. The laminar burning velocities, laminar burning fluxes and Markstein lengths at different equivalence ratios and initial pressures were obtained. Furthermore, the diffusional–thermal and hydrodynamic effects on flame front instabilities were specified, and the onset of cellularity was reported. Results show that laminar burning velocities are decreased with increasing initial pressure due to the increase of the free-stream density and the progressively more important three-body termination reactions. With increasing initial pressure, Markstein length decrease, while the laminar burning flux increases. Onsets of flame instabilities, expressed in terms of critical radius or Peclet number, were found to be promoted with increasing equivalence ratio and initial pressures, due to the combined effects of diffusional–thermal and hydrodynamic instabilities.