EFFECTS OF MARANGONI CONVECTION ON TRANSIENT DROPLET EVAPORATION

Results from a computational model of transient droplet vaporization a re presented. In this model, axisymmetric flows around translating sin gle component droplets are assumed. The governing equations are expres sed in finite volume form and solved numerically for transient velocit y, species and temperature profiles. Fully variable properties in the gas and liquid phases are allowed (except for liquid densities, which are held constant), and pressures of 1 and 10 atm are considered. A un ique feature of the calculations is the inclusion of surface-tension g radients resulting from droplet surface temperature variations. Result s show that surface-tension gradients significantly affect droplet int ernal temperature and velocity fields even when initial droplet Reynol ds numbers, based on droplet diameters and free-stream conditions, are as large as 50. When surface-tension gradients are allowed at high in itial Reynolds numbers (50), droplet internal circulation rates are fo und to be initially increased for a short period of time and then sign ificantly reduced, causing bulk liquid temperatures and droplet vapori zation rates to increase at smaller rates than when surface-tension gr adients are neglected.