Multidimensional simulation of diesel engine cold start with advanced physical submodels

• Published in: International journal of engine research 2000-02, Vol.1 (1), p.1-27
• Main Authors: Lippert, A. M., Stanton, D. W., Rutland, C. J., Hallett, W. L. H., Reitz, R. D.
• Format: Article
• Language: English
• ISSN: 1468-0874; 2041-3149
• DOI: 10.1177/146808740000100101

Abstract The complex physical processes occurring during cold starting of diesel engines mandate the use of advanced physical submodels in computations. The present study utilizes a continuous probability density function to represent more fully the range of compositions of commercial fuels. The model was applied to singledroplet calculations to validate the predictions against experimental results. Analysis of a high-pressure diesel spray showed axial composition gradients within the spray. Previous wall-film modelling was extended to include the continuous multicomponent fuel representation. Using these models, the cold-start behaviour of a heavy-duty diesel engine was analysed. The predictions show that multicomponent fuel modelling is critical to capturing realistic vaporization trends. In addition, the spray-film interaction modelling is crucial to capturing the spray impingement and subsequent secondary atomization. Heating the intake air temperature was shown to result in reduced ignition delay and accelerated vaporization. Increasing the fuel temperature increased vaporization prior to and away from the initial heat release. Increasing the injection pressure increased vaporization without much change in the ignition delay. Split injections, with 75 per cent of the fuel contained in the second pulse, displayed a substantial reduction in ignition delay due to ignition of the first pulse. The timing of the first injection was found to be an important parameter due to differences in the spray impingement behaviour with different timings.