ID 146

Comparison of fuel concentration distribution of diesel spray between single- and multi-hole injectors under evaporating, non-reacting condition

 

Abstract:

A comparison of the diesel spray between single- and multi-hole injectors was observed under evaporating, non-reacting conditions. The laser absorption scattering (LAS) technique was utilized to derive the mixture for-mation process in terms of equivalence ratio. Two injection quantities, which represent pilot (0.5 mg/stroke/hole) and main injection (2.5 mg/stroke/hole) in the engines, were carried out. The start of injection (SOI) was faster for the single-hole injector than that of multi-hole injector, possibly due to the faster injection pressure built-up process inside the sac volume. Therefore, the spray penetration development was faster for single-hole injector. The spray angle for injected mass of 0.5 mg with multi-hole injector was greater than that with single-hole injec-tor, especially at the transient period right after SOI. However, the spray angle difference between single- and multi-hole injectors decreased and became almost identical when the spray entered into quasi-steady state with longer injection duration (main injection quantity case). The equivalence ratio distribution profile for both sin-gle- and multi-hole injectors exhibited similar results at the end of injection (EOI) timing under injected mass of 2.5 mg. In the case of injected mass of 0.5 mg, the single-hole injector was slightly more advantageous on forming a leaner mixture at EOI timing due to more air entrainment possibly caused by the longer penetration. The difference, however, was small due to its small injection quantity.