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This paper uses CFD methodology to simulate a prototype Diesel engine operating at high peak pressures (HPP). Under these conditions the accurate estimation of the level of thermomechanical stress on metal components is crucial for the design process. CFD simulations have been performed of flow, combustion and heat transfer to provide detailed insight into the in-cylinder behaviour of the engine. Particular emphasis was put on improving wall heat transfer predictions which have been compared with detailed local time-resolved surface heat transfer measurements. It is demonstrated that heat transfer strongly depends on flame spread via flow field and spray-related processes. Hence local heat transfer measurements also provide a stringent testing ground for spray and combustion model performance. Additionally it is shown that widely-used empirical heat transfer correlations are incapable of estimating the critical level and nature of thermal loading.

The objective of this paper is to present a numerical simulation method for the calculation of an unsteady, one-dimensional flow and heat transfer in the branched intake manifolds of multi-cylinder engines. The method operates on the one-dimensional differential conservation equations for a variable-area duct network with friction and heat transfer at the walls. The latter processes are represented by appropriate drag and heat transfer coefficient correlations, as also are the losses which occur at junctions and other geometrical irregularities. The equations are solved by a time-marching finite-volume method, on a computational mesh in which the velocities are located between the pressures which drive them.