Atomization and Sprays, Vol.26, No.8, 755-773, 2016
TIME-RESOLVED CHARACTERIZATION OF LOW-PRESSURE PULSED INJECTOR
This study concerns visualization of pulsed sprays of a gasoline port fuel injector under ambient conditions. One-, two-, and four-hole configurations all with the same hole diameter are compared. The investigations on the two-hole configuration include adjacent and diagonal holes. The instantaneous penetration length, the jet breakup length, cone angle, and the droplet diameter distributions are evaluated along the spray axis at different injection pressures. As the spray penetration evolves, the liquid jet breaks up some time later, and reaches a nearly constant breakup length throughout the subsequent development of the spray. Unlike the single-hole spray, the two-hole spray exhibits a mild increase in the breakup length with increase in the injection pressure. The breakup length with the diagonal two-hole configuration is much shorter than with the adjacent one. The diagonal two-hole configuration exhibits a high cone angle relative to two-hole and four-hole cases. In all the cases, the mean droplet size decreases with injection pressure and remains nearly constant in time at any axial location. While the single-hole and adjacent two-hole injectors indicate coalescence of droplets, the diagonal two-hole case shows a decrease in the Sauter mean diameter of the droplets with axial distance. The four-hole injector produces nearly constant droplet size. The shorter breakup length, higher spread, and smaller droplet sizes in the two-hole diagonal configuration support an enhanced entrainment of ambient air as compared to the two-hole adjacent and four-hole injector configurations.