UNSTEADY EVAPORATION AND COMBUSTION OF A DROP CLUSTER INSIDE A VORTEX

A model has been developed that describes the evaporation, ignition. a nd combustion of a drop cluster embedded in a large vortex. The purpos e of this model is to simulate the behavior of drops in large coherent vortices produced in the shear layer of a jet. The model treats the d ynamic interactions between the drops and the vortex, and also takes i nto account the drop proximity to calculate the heat and mass transfer between drops and ambient gas. The gas phase outside the cluster is t reated as an unsteady, reacting phase, whereas quasi-steadiness is ass umed between the drops and surrounding gas inside the cluster. It is a ssumed that drops will not burn individually, but as a group. The resu lts show a very complex interaction between the dynamics of the drop-l oaded vortex, the flame, and the evaporation process. A quasi-steady s tate is not always reached, depending upon the drop number density or the vortex intensity. In most cases, the flame is located very close t o the cluster. The mass ratio of burned fuel (at complete evaporation) to initial fuel is generally less than 10%.