Experimental Study on the Flow Characteristics in Turbulent Diffusion Flames : Flow Characteristics in Turbulent Diffusion Flames and the Effect of Charged Soot on Fluctuation Velocity

Abstract

The flow characteristics of turbulent jets with and without flame were studied at the low Reynolds numbers of 2000 and 3000, with fuel-rich mixtures (equivalence ratios of 6, 24 and ∞ ) of propane gas and air. Axial and radial time-mean velocities and fluctuation velocities have been measured by LDV. Temperature and luminosity have been measured by a fine thermocouple and a photomultiplier, respectively. Potential core length was presented by normalized mass flux along the axis, and by radial mean velocities in the flow with and without flames. The potential core length in the flow with flame is about twice that in the flow without flame. The turbulent intensity, measured to study the effect of charged soot, in the highly luminous soot region was smaller than that in the nonluminous region, in spite of the same temperature and the same velocity gradient. The radial displacement of particles caused by the repulsive force between charged soot induces an increase in apparent gas viscosity in the flame gas. Order estimation of the viscosity by the movement of soot was carried out using electrical mobility and the equation of motion of particles in the shear region.