SINGLE DROPLET COMBUSTION IN A GRAVITATIONAL ENVIRONMENT

A theoretical analysis is developed to study the combustion characteri stics of a fuel droplet in a gravitational field. The normalized gover ning system consists of the complete conservation equations in r-z coo rdinates and includes finite-rate global kinetics. The Clausius-Clapey ron law is applied at the liquid-vapor interface to describe the evapo ration process. A modified body-fitted grid generation technique is us ed to handle irregular boundaries. The effects of changing the droplet diameter (dBAR) and the gravity level (gBAR) are investigated. Under the variation of droplet diameter, flame structures, including isother ms, flame shape, velocity vector field, and mass burning rate are stud ied in detail. The predicted results exhibit good agreement with exper imental data. When the gravity level increases, the computed results s how that the flame shape is sensitive to variation in gravity. A simpl e correlation, mBAR = m0BAR [1 + const. (alpha/gBAR)0.52], is found. W ithin the elevated gravity domain of experiment, the computed data agr ee well with measurements obtained by Okajima and Kumagai [10].