Stratified scavenging computations in two-stroke engines using Open FOAM

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Sweden, G¨oteborg, Chalmers University of Technology, 2010. 53 p. Master’s Thesis in Automotive EngineeringAbstractThis report presents the methodology and the results of simulations of the flow in aStratified charged two-stroke engine. The focus is put on the process and performanceof the scavenging. To simulate the flow through the engine the finite volume methodin three dimensions is used. The OpenFOAM-1.5-dev computational fluid dynamicssoftware is used to perform the calculations. The performance and possibilities thatOpenFOAM-1.5-dev gives for this kind of applications is evaluated.ContentsAbstractContentsNomenclaturePrefaceAcknowledgementsIntroductionBackground Aim and purpose Theory The two-stroke engine Conventional two-stroke engine Stratified charged two-stroke engine The governing equations The RANS-equations and turbulence modeling The finite volume method Fluids Approach Limitations Method Engine geometry Engine geometry medications Mesh generation The H576 engine geometry The block geometry Dynamic mesh with topology changes Liner and ports Deforming mesh Layer addition and removal Sliding interfaces Mesh quality In data from 1-D software Discretisation schemes Time derivatives Gradient terms Divergence terms Laplacian terms Boundary conditions Walls Inlets and outlets Time step and convergence criterion Setup for calculations in parallel Layer addition and removal in parallel Sliding interfaces in parallel Domain decomposition Assumptions and approximations Fluids and combustion Initial field values Results Scavenging and trapping efficiency Validation Commercial 1-D software Turbulence modeling Commercial 3-D software Conclusions Discussion and recommendations