Liquid Pattern And Velocity Field On A Surface During Spray Impingement

Abstract

The process of fuel injection and the associated wall impact is critical for the quality of combustion in engines. Secondary droplets and wall deposits are strongly related to incomplete combustion and soot emissions. To reduce harmful emissions and optimise the combustion, further investigations of the processes of spray impingement, secondary droplet formation and wall film formation are of central importance. In order to obtain a more comprehensive picture of the interaction between spray and wall, light sheet visualizations and particle image velocimetry (PIV) measurements were performed on an impinging gasoline spray within a conditioned pressure vessel. For this purpose, measurements were conducted both perpendicular to the jet axis and parallel to the wall. The focus here is on the conditions in a modern, homogeneously operated gasoline engine with a high-pressure injection valve with a well-known spray. The spray under investigation has already been studied using high-speed shadowgraphs and phase doppler anemometry measurements. The combination of the data allows validation and a better understanding of the present measurements. The injection pressure was 150 bar, the vessel temperature 80°C, and the nozzle-to-wall distance 35 mm. The vessel pressure was varied from 0.4 bar to 6 bar, which represents typical charge conditions in an engine. The measured data allowed the analysis of the internal structure of the spray and the quantification of the flow movements before and after the spray impact. The results obtained provided detailed new insights into the relevant sub-processes.