Numerical Simulations for Spray Characterization of Uneven Multiple Jet-to-Jet Impingement Injectors

Spray structure has a significant effect on emissions and performance of an internal combustion engine. The main objective of this study is to investigate spray structures based on four different multiple jet impingement injectors. These four different multiple jet-to-jet impingement injectors include 1). 4-hole injector (Case 1), which has symmetric inwardly opening nozzles; 2). 5-1-hole (Case 2); 3). 6-2-hole (Case 3); and 4). 7-3-hole (Case 4) which corresponding to 1, 2, 3 numbers of adjacent holes blocked in a 5-hole, 6-hole, and 7-hole symmetrical drill pattern, respectively. All these configurations are basically 4-holes but with different post collision spray structure. Computational Fluid Dynamics (CFD) work of these sprays has been performed using an Eulerian-Lagrangian modelling approach. First, the present work visualizes spray structures and explores the trend of ‘post collision’ and ‘bend’ angles of four different injectors in two different clip-plane views which are named View 1 and View 2. Pressure and velocity fields in spray chamber are analyzed to study their effects on spray structures. Finally, mass and droplet size distributions are employed to observe spray structures and investigate collision efficiency. Conclusions from the present study are that post collision angle has no significant difference in View 1 but decreases from Case 1 to Case 4 in View 2, as well as post collision angle and bend angle have an influence on spray penetration and structure. Additionally, spray velocity is studied as it affects the spray structure. Finally, droplet size and number distributions of in both vertical and horizontal cross sections of a spray show the droplets at center region of the spray exhibit smaller diameter than those at outer zone.