Turbulent transient gas injections

Compressible transient turbulent gaseous jets are formed when natural gas i s injected directly into a diesel engine. Multi-dimensional simulations are used to analyze the penetration, mixing, and combustion of such gaseous fu el jets. The capability of multidimensional numerical simulations, bused on the k-epsilon turbulence model. to reproduce the experimentally verified p enetration rate of free transient jets is evaluated The model is found to r eproduce the penetration rate dependencies on momentum, time. and density, but is more accurate when one of the k-epsilon coefficients is modified The paper discusses other factors affecting the accuracy of the calculations, in particular, the mesh density and underexpanded injection conditions. Sim ulations are then used to determine the impact of chamber turbulence, injec tion duration, and wall contact on transient penetration. The model also sh ows that gaseous jets and evaporating diesel sprays with small droplet sire mix at much the same rate when injected with equivalent momentum injection rate.