Development of a Phenomenological Diesel Spray Model after End-of-Injection with Varying Injection Rate

抄録

In order to perform parametric study on advanced combustion process in diesel engines, zero-dimensional diesel spray model is needed to predict the diesel spray propagation including the spray evolution after end-of-injection (EOI) with varying injection rate. In this study, a previous phenomenological spray model including the spray evolution after EOI with constant injection rate was improved to predict the spray penetration after EOI with varying injection rate. The effective injection velocity was defined by the ratio of the momentum flux and fuel mass flow rate integrated over the tip cross-sectional area of the diesel spray, and the analysis of the effective injection velocity variation was performed during and after injection. The results were combined with the vortex theory to derive the effective injection velocity and its response time to the injection velocity. After that, the fuel mass flow rate over the tip cross-sectional area was derived for varying injection rate even after EOI. Then the momentum flux over the tip cross-sectional area was calculated, so that the spray penetration was obtained based on the momentum theory. The developed model was validated by comparing with a one-dimensional discrete spray model and experimental data.