The present work investigates the in-nozzle phenomenology of cold fuel injections. Large Eddy Simulations (LES) were performed using a 3D model of a step nozzle injector with water and iso-octane serving as working fluids and the examined cases spanning across a range of temperatures that is relevant to an engine’s start-up operation. The aim is to shed light on the influence exerted by temperature on the in-nozzle cavitation mechanism, which in turn affects the primary atomization and the structure of the downstream emerging spray.
Results suggest that a decrease in the injected fuel’s temperature induces a reduction of the nozzle’s void fraction and a shrinkage in the streamwise length of the cavitation region. This suggests that the size and intensity of the hydrodynamic cavitation features tend to become suppressed in cold conditions. The phenomenon appears to be driven by the temperature dependence of the injected fluid’s thermophysical properties, primarily the vapour pressure, with lower values hindering phase change.