Experimental study on macroscopic spray characteristics after impingement in a slit-type GDI injector

Abstract

In this paper, an experimental study on the wall-impinging spray of the slit-type GDI injector is presented. To examine the effects of various factors on the development of a spray impinging on the wall, experiments were conducted at various injection pressures, ambient pressures, wall distances from the injector tip, wall temperatures, and wall inclination angles. Behavior of the impinging spray was visualized using a planar laser scattering method. It is shown that the spray path penetration of the wall-impinging spray increases with increases in injection pressure, wall distance, wall temperature, or wall angle. On the other hand, the spray path penetration of the wall-impinging spray decreases with increases in ambient pressure. The predicted spray path penetration calculated by the empirical equation estimates the spray path penetration in all cases, and the empirical equation is optimized for the total injection pressure.

An experimental study on spray characteristics after impingement on a piston surface through an asymmetrical multi-hole injector of a direct-injection spark ignition gasoline engine

“…It can be seen that the time of spray-wall impingement was delayed as the ambient pressure increased, owing mainly to an increase in the ambient pressure which resulted in a decrease in the spray tip speed. The impinging spray tip penetration decreased as the ambient pressure increased; this trend is the same as the results of the slit-type GDI injector at an injection pressure of 12 MPa and an impinging angle of 90° [14], mainly because the higher ambient pressure results in an increase in the surrounding gas density, which increases the drag force acting on the development of fuel droplets. The left and right spray tip penetrations under the 0.1 MPa ambient pressure condition are on average about 7.7 mm and 1.8 mm respectively larger than under the 0.6 MPa ambient pressure condition.…”

“…Also, on comparing the spray tip penetration before and after the spray had impinged on to the piston top surface, it can be seen that the slope of the curve decreased but that the elevated injection pressure improved the rising rate of the impinging spray tip penetration. The results on the impinging spray tip penetration are different from those of the reference (an injection distance of 30 mm, an ambient pressure of 0.5 MPa, and an ambient temperature of 373 K [14]) which increased with increasing injection pressure, because the higher temperature and ambient pressure conceal the effect of the higher injection pressure on initial spray atomization.…”

“…Although many impinging spray experiments have been conducted for diesel and GDI injectors, generally, a plain plate was selected as an impact wall [13,14], and a single side impinging spray tip penetration, impinging spray radius, and impinging spray height were calculated in the previous investigations, but, in the investigations, the data for the intake side and the exhaust side were calculated separately in order to characterize the impinging spray of an asymmetric multi-hole injector.…”

“…It seems that the droplets have more momentum owing to the lower ambient pressure, resulting in greater energy transfer during rebound. This resulted in a steeper slope than for the other impingement sprays [14].…”

Development and Evaporation of Group-Hole Nozzle Sprays under Various Surrounding and Impinging Conditions of Direct-Injection Diesel Engines

“…The total spray tip penetration S was defined as the summation of impingement distance L w to half the total radial spray length, (r L + r R )/2. Owing to enhanced spray momentum in the downward direction, S L at 45u impingement angle was longer than S at 90u impingement angle for all test nozzles [24,25]. As mentioned in section 4.1.1, at the vertical wallimpingement condition, the spray tip penetration of the GH/a10 nozzle spray has higher penetrating rate than the SH/0.135 nozzle spray after wall impingement and it finally overtakes the spray tip penetration of the SH/0.135 nozzle spray at around 1.0 ms ASOI.…”