Effect of cross-flow velocity on spray evolution and impingement characteristics of a multi-hole port fuel injector

Abstract

The location and orientation of the injector play a crucial role in determining engine performance and emissions from spark ignition and dual-fuel compression ignition engines. This study focuses on the spray atomization and downstream mixing of gasoline injected from a multi-hole port fuel injector in a crossflow. This study employed the phase Doppler interferometry technique to extract the droplet size and velocity distributions for the flow confined in a circular duct with a diameter similar to the intake port of the dual-fuel compression ignition engine. The flow velocity was maintained at 10 m/s at 1 atm pressure and 299 K temperature. The spray characteristics were compared for the quiescent and crossflow cases. The spray evolution was analyzed using a high-speed imaging technique. Near wall impingement analysis has been carried out using the spray impingement models. The early stage spray evolution was similar for the quiescent and crossflow cases. The horizontal velocity of the spray was found to be ∼12 m/s at 20 mm downstream of the injector. The velocity remained similar for the flow and no-flow cases, as drag force was found to have an insignificant effect. The drag force was estimated to be one order of magnitude higher for the 15-μm droplet than the 50-μm droplet. The maximum Sauter mean diameter observed for the flow case inside the spray was 53 μm, which was 18% higher than the maximum Sauter mean diameter of the no-flow case. The droplet Sauter mean diameter increased along the spray due to the coalescence of slow-moving droplets. The droplet breakup was found to be insignificant downstream of the spray. The flow entrained the droplets smaller than 30 μm. The spray-wall impingement criterion estimated around 42% of droplets to bounce off the surface at 50 mm, compared to 22% without flow.