ID 11

Experimental and computational investigate of liquid injection transients in real nozzles

 

Abstract:

The present paper focus on the transient events of liquid jet injection, especially the first observable liquid and the last one, with microscopic view. High Pressure multihole injectors are considered for this study with round holes. Especially, for the opening event the focus is on the slow opening needle velocity case where mushroom are observed, as in few former publications. For the closing event, in addition the effect of fouled nozzle is tested. In complement, simulations are proceed. A single fluid, two phase, is employed to reproduce numerically these cases together within the Volume Of Fluid approach, and cavitation modeling. The turbulence is modeled using Large Eddy Simulation one equation. The proposed simplification is to not include the needle movement but to model opening and closing by a change of the inlet boundary conditions. It is demonstrated that the simulation can capture very well the topology of the flow as experimentaly observed, for both events, opening (mushroom and ring) and closure (disintegrating hollow corona). It also contributes to explain the effects of the early shear and vortex cavitation events on the initial jet disintegration. Concerning closure, a phenomenological model is proposed on the effect of the final sheet disintegration in terms of generation and consequence for the nozzle tip wetting.