Theoretical and Experimental Studies on Evaporation and Combustion of a Single Fuel Droplet
L.-X. Zhou1, X.-Z. Wu1, F. Wang2
1Department of Engineering Mechanics, Tsinghua University, Beijing, China
2School of Energy and Power Engineering, Beihang University, Beijing, China
Keywords: droplet evaporation, droplet combustion, theoretical study, experimental study
Abstract
The evaporation and combustion of fuel droplets have been studied since the middle of the last century. Existing spray combustion modeling is based on a simplified one-dimensional model. This model, as well as recently developed three-dimensional combustion models for single droplets, do not describe the conditions under which various droplet combustion regimes exist. In this paper, droplet evaporation and combustion are studied using hydrodynamic and experimental methods. The hydrodynamic section considers a two-dimensional axisymmetric evaporating and burning droplet. The equations of motion are solved using an integral method similar to the Karman-Pohlhausen method for calculating the boundary layer in the presence of a pressure gradient. The resulting solution yields a local evaporation rate and flame radius consistent with known experimental data. In the experimental section, the influence of relative gas velocity, pressure, and gas temperature on droplet evaporation and combustion processes is determined. Various droplet combustion regimes at different relative velocities are experimentally revealed, explaining the change in the evaporation constant with increasing relative velocity. The theoretical results are confirmed by experimental studies of suspended droplet evaporation.
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