Correlating the Nozzle Flow to Spray and Primary Breakup using Visualization and Multi-phase Simulation

In this paper we use a combination of visualization and simulation to correlate the internal nozzle flow to spray and primary breakup using Visualization and multi-phase simulation techniques.  For simplicity, three-hole diesel nozzles with and without honing are used.  The purpose is to simplify the flow diagnostics but without loss of generality.  The time-resolved Phase-Contrast x-ray visualization technique was employed to visualize the liquid-gas interfaces just outside the nozzle.  A multi-phase URANS simulation is carried out at different needle lifts to predict the flow regimes inside and directly outside the nozzle to account for the various multiphase flow physics.  The results show that while Turbulent Kinetic Energy (Tke) dominates as the primary source of breakup energy at high lifts, Non-Axial Kinetic Energy (Ek) is dominant at low needle lifts.  Further the unhoned nozzle produces stronger atomisation due to higher levels of cavitation, stronger vortices and higher levels of Tke.