Experimental Investigation of Spray Characteristics Direct Injected in Atmospheric Ambient Conditions by a Multi-Hole Injector

The aim of the present work was to characterize macroscopic spray parameters of a multi-hole direct injection injector for spark ignition engine applications. The geometry, the position of spray boundaries the overall cone angle, the spray vertical penetration and the vertical spray length were evaluated by processing the spray images recorded at 3300 frames per second. The frequency of recording images was suitable for capturing all the spray developments in all tested conditions. The tested fluid was EXXSOL D60 for simulating ethanol spray characteristics due to its similar properties and due to security reasons. The injector was tested outside the engine and into an open acrylic chamber being injected into atmospheric air conditions of the laboratory. The injection pressure was set up in 100 bar and the simulated engine speed were set up in MOTEC ECU in 3000 rpm, 3600 rpm and 4000 rpm. The injection durations were set up in 3,0 ms for 3000 rpm and 2.3 ms for 3600 rpm and 4000 rpm. The spray vertical lengths and the spray vertical penetrations were coincident and consequently showed same results in the period when the injector was discharging the tested fluid. The results showed that after the end of spray injections the spray penetration kept increasing normally while the spray vertical length decreased immediately after the end of injections and after this rapid decrease it continued the increasing behavior. No significant differences were found in cone angle, vertical penetrations, vertical spray length and spray overall cone angle when the simulated engine speed was varied.