Convection heat transfer of colinear interacting droplets with surface mass transfer

Abstract

A validated computer simulation model has been developed for the analysis of colinear droplets in a heated gas stream. Using a finite-element method, the complete gas-phase transport equations have been solved describing quasi-steady laminar axisymmetric flow past closely spaced monodisperse constant-diameter droplets with blowing. The liquid-phase motion is represented by Hill's spherical vortex, coupling the gas-phase shear stress with the tangential surface velocity of the droplet. Of interest are the coupled nonlinear interaction effects on the fluid-flow patterns and temperature fields for different free-stream Reynolds numbers (10≤Re≤200(, interdroplet distances (1.5≤ d ij ≤6.0), lhe liquid-gas viscosity ratios (1≤ ϰ≤100), and Stefan or heat transfer numbers (0≤BH≤5.0). Surface mass transfer (blowing) and associated wake effects reduce both the total drag coefficient and the average Nusselt number for each interacting droplet when the Reynolds number increases. Large liquid-gas viscosity ratios, i.e., ϰ>20,, have hardly any effect on the drag coefficient and Nusselt number ratios. However, droplet sspacing at d ij ≤6 and intermediate Reynolds number have a profound effect on all droplets, especially the second and third one, which experience significantly reduced drag and heat transfer at small interdroplet distances.