Numerical Analysis of Initial Shape of Nozzle Inject Flow

At the initial stage of injection, the inject flow has not yet broken up and in a range of small atmosphere pressure (16∼500KPa), the tip of the inject flow always forms a shape of mushroom. And the umbrella of the mushroom is always very big and the root of it is always very thin, especially when the atmosphere pressure is relatively low (88KPa, or 100mmHg) ⁽¹⁾⁽²⁾. These phenomena are not known popularly and the reason of mushroom formation is not clear. In this paper, with MARS (Multi-interfaces Advection and Reconstruction Solver) method ^(3)(4)(5)for simulating free surface, analysis of inject flow is practiced. The phenomena are reproduced and the reason is cleared that the formation of the mushroom is induced by the momentum exchange between the very high speed fuel flow and the very complex air flow.