Cylinder combustion pressure calculation in direct-injection diesel engine based on KIVA-3V

To calculate cylinder combustion pressure an enthalpy defect is introduced in the CFD (computational fluid dynamics) code (KIVA-3V). CFD-modeling of the combustion process in a DI (direct-injection) diesel engine requires mathematical models for all the described processes in order to capture the correct physics and chemistry. Assuming unity Lewis-numbers, the transport equation for the turbulent mean value of the enthalpy, neglecting the contribution due to radiation, is deducted. In the conventional flamelet enthalpy equation, none of the heat loss terms are retained. The objective here is to find a way of accounting for the effects such heat sinks. In the present analysis evaporation rate issue is left open, since focus is on processes that are of importance at times when there is little or no evaporation. Heat loss due to viscous dissipation can safely be neglected for the purpose of this discussion. Besides, the pressure transport equation is got when an enthalpy defect is introduced the turbulent mean value of the enthalpy transport equation. Finally, different simulation results at different SOI (start of injection) angles are compared with experiments. It gives the theory and method about calculating cylinder combustion pressure exactly in DI diesel engine.