Zero-dimensional ROHR simulation for DI diesel engines – A generic approach

In order to minimise time and cost for engine development, simulation tools are needed for pre-optimisation of the thermodynamic working cycle. Due to the increasing number of possible degrees of freedom in the engine management system, the focus is on simulation tools with short computation time. The paper describes a generic strategy for the development of zero-dimensional combustion models using the basic reaction rate equations by Arrhenius and Magnussen. Pursuing this strategy, models for ignition delay and pre-mixed combustion were developed based on equations to describe the influence of both the temperature and the turbulence density on the reaction rate. Regarding the heat release rate (ROHR), the well known zero-dimensional Magnussen approach based on integral values for available fuel mass and turbulence density was extended by a more detailed description of the mixing process in the injection spray. Thus, the heat release rate in the flame sheet around the spray can be calculated and added to the heat release rate in the region outside the spray and after end of injection.