(1-26) A Spray Wall Impingement Model Based upon Conservation Principles((FS-3)Fuel Sprays 3-Modeling)

Abstract
A spray wall impingement model that conserves mass, tangential momentum, and energy of an impinging parcel is developed for multidimensional spray calculations. This model focuses on spray impact on dry and wet surfaces below the fuel's Leidenfrost temperature, a scenario encountered under typical engine operating conditions [10]. The model is integrated into the KIVA-3V framework. Three splashing parcels and one wallfilm parcel are used to represent the shattering of a splashing droplet upon impact with the surface. It is assumed that the impulsive force on an impinging droplet normal to the surface is dominant allowing one to treat the magnitude of its tangential momentum component constant after impact. The viscous dissipation of an impinging droplet and kinetic energy of the wallfilm are accounted for in the energy conservation equation. The new spray impact model is validated using experimental measurements of a evaporating solid cone spray of n-tridecan at 550K impinging normally onto a flat plate at elevated temperature and pressure [7]. The new model shows improvements over a group of previous impingement models in predicting the spread rate of the liquid and vapor phases the spray. An energy balance of a splashing impinging parcel illustrates that more than half of its incoming energy is lost to viscous dissipation at high Weber Numbers (We). Most of the remaining energy is consumed by the kinetic energy of the smaller secondary parcels. At lower We, viscous dissipation decreases in magnitude, while the energy used to form a wallfilm on the surface becomes predominant. Finally, the effects of injection velocity and wall temperature on the radial penetrations of the liquid and vapor are investigated.

This publication has 0 references indexed in Scilit: