Characteristics of turbulent spray combustion in a piloted jet flame burner

Abstract

A laboratory burner has been developed for turbulent combustion of a spray jet, with special emphasis on case of modeling. The flow field is fluid mechanically well understood, so that the focus can be on evaporation and other aspects of turbulence/droplet interaction. Droplet size, volume flux, and two-component velocities are measured at several axial locations downstream of the burner exit with the phase-Doppler anemometry technique. The gas flow velocity profiles of the spray flames investigated here are similar to those of conventional premixed jet flames. This is attributed mainly to the use of air as the spray carrier. There is clear evidence that droplets greater than 30 μ m do not follow the turbulent flow velocity fluctuations. Between a high- and a low-speed spray flame, self-similarity on the domain of the flight time is observed in droplet mean diameters and the droplet number density. The effect of turbulence on local droplet evaporation is found to be negligible.