Influence of the Spatially Resolved Nozzle Hole Exit Flow Distribution on Diesel Spray Development

Abstract

ABSTRACT The internal flow in Diesel injector nozzles significantly affects the spray formation, atomisation and air/fuel mixing rates. A multi-dimensional model has been developed to numerically predict the spray evolution patterns with particular focus on capturing the influence of the injector nozzle flow on the near-nozzle spray dispersion. The link to the internal flow is established by using as initial conditions for the injected fuel, the transiently and spatially resolved distribution of the flow field at the nozzle hole exit plane as calculated from a multi-dimensional and multi-phase nozzle flow simulation model. The local spray dispersion angle is estimated by assuming that the disintegration of the liquid jet is function of the distribution of liquid velocity, cavitation vapour volume fraction and liquid turbulence level at the exit of the injection hole. Results confirm that the internal nozzle flow and in particular formation of cavitation, significantly affects the initial spray dispersion angle in a transient manner, in agreement with flow visualisation experiments inside transparent nozzle replicas.