Development Of Numerical Simulation For The Process Of Two Phases Reacting Flow In Cylinder Based On Unstructured Grids

As today’s main energy consumption and one of the main sources of environmental pollution, internalcombustion engines call for the attention of many researchers’ interests. The numerical analysis method hasopened up a new path to direct experiments and designs with theories. It is becoming a significant tool inanalyzing the combustion process of IC engines and new product research and development. The keyelements in numerical simulation of internal combustion engines consist of moving mesh generation, spraymodeling, combustion and chemical reaction modeling, and the cylinder flow field numerics. The mainobjective of the present thesis is the development of suitable numerical methods for internal combustionengine applications including moving mesh method, fuel spray, mixture formation and combustion.In order to improve the efficiency in analyzing in-cylinder process, a pre-processor for the movingmesh generation is developed. It consists of “spring method”,“dynamic layer method” and a refining andcoarsening grid algorithm. Also presented is a “merge-split” method, which is designed for variable domainof in-cylinder process by merging and splitting groups of computational cells at the same time.For locating the particles in a fuel spray, a fast particle tracking method is proposed. A particle’slocation is decided based on the relationship of its position vector and cell faces. A “virtual triangulationmethod” is developed to alleviate the non-planar problem caused by the numerical error. For non-planarcell faces associated with unstructured polyhedral meshes, the polygon of a surface is triangulated in orderto avoid “missing particles” associated with non-planar faces.A two-phase reacting flow modeling approach is developed applicable for unstructured grid finitevolume framework. The gas phase is solved by the Euler method. The governing equations are discretizedover finite volume of unstructured meshes. The pressure-velocity coupling is solved by SIMPLE algorithm.The Lagrangian discrete droplet method (DDM) is used for the liquid. Full two-way coupling betweenliquid phase and gas phase are considered.The developed technologies are implemented in an in-house software and is used to study the spraypenetration process, single-droplet evaporation, mixture formation and spray impingement on solid walls. Itis also applied for in-cylinder simulations with or without (pure compression) spray combustion. Validationof the models is accomplished through the comparison of experimental results with simulations. The workdemonstrated that the developed software can be used for the simulation and analysis of in-cylinder flow,spray and combustion process of internal combustion engines.