Combustion of a Spinning Fuel Droplet

A theoretical investigation into the effects of rotation on the burning characteristics of an isolated fuel droplet is presented. Rotation induces a secondary flow in the gas phase inward towards the droplet poles and outward from the equator. Overall, additional heat is transported from the flame to the droplet, enhancing the vaporization and burning processes and shortening the droplet lifetime. Explicit expressions are given for the burning rate and for the variations in the droplet diameter. The distorted flame shape and the modified flame stand-off distance are also determined. Although it enhances the burning, the swirling makes the flame more susceptible to extinction. It is found that when extinction occurs it first takes place locally either at the poles of the flame sheet or at the equator, depending on how far conditions are from stoichiometry.