Jet Mixing in a Model Direct Injection Diesel Engine with Swirl

Computational and experimental results are reported of an investigation into jet mixing, using the hydraulic analogue technique to simulate the diesel injection process. Steady state and impulsive injections into both quiescent and swirling flow fields are considered. A comparison between predictions and experimental results shows a deficiency in the turbulence model's capability to predict recirculation zones downstream of the point of injection. The relative effect of swirl on jet penetration is examined and it is argued that a non-uniform injection characteristic leads to a more rapid formation of a combustible mixture, thereby reducing the ignition delay period and the pressure gradient during combustion.