Experimental Study on Unsteadiness of n-decane Single Droplet Evaporation and Effect of Natural Convection on Droplet Evaporation at High Pressures and Temperatures

Abstract

Evaporation of a single n-decane droplet at high pressures and high temperature has been studied experimentally under normal and microgravity conditions. Ambient pressure was set at 0.10 and 0.50 MPa. Ambient temperature was fixed at 773 K. At normal gravity, initial droplet diameter was varied from 0.4 to 0.80 mm. To examine unsteadiness of droplet evaporation, instantaneous droplet evaporation rate coefficient was measured. The effect of natural convection on instantaneous droplet evaporation rate coefficient was evaluated as a function of the Grashof number. The unsteadiness of droplet evaporation appears in entire period of evaporation lifetime. The effect of natural convection on instantaneous droplet evaporation rate coefficient changes during evaporation and its dependence on Grashof number in the range where the effect of natural convection was regarded as quasi-steady was expressed as the empirical equations.