Modeling of DISI Engine Sprays with Comparison to Experimental In-Cylinder Spray Images 2001-01-3667
In modeling of engine fuel-air mixing, it is desired to be able to predict fuel spray atomization under different injection and ambient conditions. In this work, a previously developed sheet atomization model was studied for this purpose. For sprays from a pressure-swirl injector, it is assumed in the model that the fuel flows out the injector forming a conical liquid film (sheet), and the sprays are formed due to the disintegration of the sheet. Modified formulations are proposed to estimate sheet parameters including sheet thickness and velocity at the nozzle exit. It was found that the fuel flow rate of a swirl injector satisfied the correlation well. Computations of correlation well. Computations of the sprays injected in an engine with a side-mounted injector were performed for conditions that duplicated a set of experiments performed in an optical engine. The computed results were compared with the spray images obtained from the optical engine using elastic (Mie) scattering. Both early and late injection schemes were studied and fairly good agreement between computation and experiment was obtained. It was found that in this particular engine configuration the spray was lifted from its axis toward the chamber roof at the late injection mode while it was deflected from its axis in an opposite direction for the early injection mode. Analysis of the modeling indicated that these phenomena were related to the complicated spray and gas flow interactions.