Simulation of Heavy Fuel Spray and Combustion in a Medium Speed Diesel Engine 962053

The purpose of the paper is to present injection results of heavy fuel spray at room temperature conditions and combustion predictions in a medium speed diesel engine using the k-ε turbulence model in KIVA2. The work consists of two main parts. In the first, the heavy fuel spray is simulated at cold test chamber conditions in which the density of gas is of the same order of magnitude as in the engine at the end of compression. The predicted spray tip penetration and droplet sizes are compared to the measured values. The second part deals with the combustion simulation using the Magnussen and Hjertager ( M&H ) or Magnussen Eddy Dissipation Concept ( EDC ) turbulent diffusion combustion model. The cylinder pressures and heat release in the simulation are compared to the measured values.

From the spray verification results it can be seen that it is difficult to obtain good agreement for the spray penetration and the droplet sizes with experimental data using the TAB ( Taylor Analogy Breakup ) drop breakup and the DDM ( Droplet Distribution Method ) spray model.

The predicted cylinder pressure and the heat release distributions with the M&H model and especially with the EDC model match the experimental data quite closely. The modified KIVA2 simulation model is able to predict reasonably well the combustion process of a medium speed diesel engine.