Numerical and Optical Evolution of Gaseous Jets in Direct Injection Hydrogen Engines

This paper performs a parametric analysis of the influence of numerical grid resolution and turbulence model on jet penetration and mixture formation in a DI-H2 ICE. The cylinder geometry is typical of passenger-car sized spark-ignited engines, with a centrally located single-hole injector nozzle. The simulation includes the intake and exhaust port geometry, in order to account for the actual flow field within the cylinder when injection of hydrogen starts. A reduced geometry is then used to focus on the mixture formation process. The numerically predicted hydrogen mole-fraction fields are compared to experimental data from quantitative laser-based imaging in a corresponding optically accessible engine.

In general, the results show that with proper mesh and turbulence settings, remarkable agreement between numerical and experimental data in terms of fuel jet evolution and mixture formation can be achieved. The grid resolution is found to have significant influence on the jet penetration, and almost no effect on the fuel dispersion. In order to improve the prediction of local values of air/fuel ratio, tuning of the turbulence model is performed. Results show that the turbulence model affects fuel dispersion but not jet penetration.