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Modern diesel engines operate under injection pressures varying from 30 to 200 MPa and employ combinations of very early and conventional injection timings to achieve partially homogeneous mixtures. The variety of injection and cylinder pressures, as well as injector dynamics, result in different injection rates, depending on the conditions. These variations can be captured by 1-D injection models that take into account the dynamics of the injector, the cylinder and injection pressures, and the internal geometry of the nozzle. The information obtained by these models can be used to provide initial and boundary conditions for the spray modeling in a 3-D combustion code. In this paper, a methodology for coupling a 1-D injection model with a 3D combustion code for direct-injected diesel engines is presented. A single-cylinder diesel engine has been used to demonstrate the capabilities of the model under varying injection conditions. Moreover, this coupling strategy opens a new methodology for 3-D calculations that do not need to fit initial conditions but use directly a 0-D model for intake/exhaust conditions and injection conditions. Using coupling strategy makes easier to run 3-D engine simulations, reduce engineering time and allows to investigate a large range of interesting phenomena. |
