RANS simulation of a multicomponent underexpanded gaseous jet mixing-effects of composition and injection conditions

Fuel injection and mixing processes determine quality of the subsequent combustion in a DI engine, and description of these processes is vital to optimize the engine performance. Reynolds-averaged Navier-Stokes approach was applied as a cost-effective tool to simulate the mixing process of a multicomponent gaseous fuel jet of various compositions typical for alcohol reformates. To learn about the physics of reformate mixing, a hydrogen-rich multicomponent jet behavior in a constant-volume chamber was investigated at conditions typical for ICE. The CFD model was validated using a reference case from the published literature. Various Impact of the gaseous jet composition, injection pressure and nozzle diameter on its behavior were studied. The important new finding shows that rising the injection pressure or increasing the nozzle diameter won't affect the jet wall impingement timing for bore sizes typical for light-duty vehicle ICEs. Furthermore, it is shown that the integral parameters of a multicomponent gaseous jet in ICE are mainly determined by the molar weight of the injected gas mixture even with high molecular diffusivity species in the mixture like hydrogen.