Experimental Investigation of Spray Characteristics Direct Injected in Atmospheric Ambient Conditions by an Inwardly-Opening Pressure Swirl Injector

An inwardly-opening pressure swirl injector for direct injection spark ignition engine applications was used in this work for injecting EXXSOL D60 into laboratory gaseous atmospheric conditions into an open chamber. The EXXSOL D60 fluid was used due to its some similar physical properties to Ethanol fuel. Four injection pressures were used in this work: 50 bar, 60 bar, 70 bar and 80 bar and the simulated engine speed was set up in 2000 rpm in all cases using the injector outside the engine. Shadowgraph technique associated to a filming process with a rate of acquisition of 3300 frames per second was used for acquiring the spray images. The spray images were treated running scripts in Matlab software. The scripts were written for this present analysis. The injector used in this work produced hollow cone sprays. With the image treatment performed in Matlab software, the vertical penetration length and the external cone angle were obtained. The main results showed that penetration length is dominated by the pre-spray in the beginning of injections until 1.1 milliseconds after start of injections in all cases. The pre-spray also promoted variability in spray behavior in the beginning of injections. The vertical penetration lengths increased when injection pressure also increased that was an expected result and no significant differences in spray cone angle that stayed around 60 degrees in all cases are observed. The present work is a tool for better understanding some characteristics of air and fuel mixture and can be used to support future computational fluid dynamics investigations in direct injected sprays for internal combustion engine applications.