Effect of Local Flow Field Fluctuations on Characteristics of Turbulent Flames

Abstract

This paper focuses on the experimental measurements of turbulence and its effect on the local consumption speed of premixed syngas-air mixtures. The flow field visualization using Particle Imaging Velocimetry (PIV) technique is also implemented to make a better understanding of the turbulence characteristics of syngas (H2-CO)-air combustion. The velocity fluctuations, turbulence intensities and local propagation velocities along the burner exit had been determined at different blockage ratios. With the increase of blockage ratios the velocity fluctuations increased in axial direction for both isothermal and reacting flows at a fixed Reynolds number (Re=2000) and equivalence ratio(Ф=.9).For reacting flows the fluctuations decreased up to the reaction zone then increased substantially at both blockage ratios. Turbulent flame propagation velocities were also determined at constant laminar burning velocity for different syngas mixtures. The effect of diluents (N2 and CO2) on turbulent burning velocities of syngas is determined at a constant adiabatic flame temperature of 1900K and at different blockage ratios. Turbulent flame propagation velocities increase with the increase in the blockage ratios. Turbulent flame propagation velocities increase with increase in hydrogen content in the syngas mixtures at constant laminar burning velocity.