Investigation On Simulation Of Complex Flow And Heat Transfer In An Engine Cylinder Head

As the important component of an engine, cylinder head has a complex structure, and endures high heat and mechanical loads in the process of engine working. It is easy to cause local overheat at the region where has a bad design or insufficient cooling, and give birth to crack under the high and low frequency thermal impact which can make the cylinder head invalid, and has an effect on intensity and reliability of an engine. Thus, it's a very important signification for evaluating heat load of an engine to design a good cylinder head and water jacket structure quickly and efficiently.In this thesis, the author takes the cylinder head and water jacket of a developing gasoline engine as the research object. Through analyzing the heat transfer process of heated components, combining the structure of cooling system and flow characteristic of coolant, physical models was established for complex flow and heat transfer in engine cylinder head, and relevant mathematic model was selected.After determining of the geometric model of cylinder head and water jacket, the paper determined the mesh size which can not only meet computational precision but also take full advantage of the available computer resource by computing the mesh independence. Discuss the flow and heat transfer boundary conditions in detail for coupled fluid-heat computational model, and determined the best heat transfer boundary condition imposed on the floor plate of cylinder head.Summarized the evaluate principle for cylinder head design. Through evaluating the results gained by directly coupled fluid-heat method to cylinder head and water jacket designed by experience when the engine works under the maximum heat load, found that there are some insufficiencies in geometric model. Then three sorts of remodeled cylinder head and water jacket design cases were put forward, and the final design which can meet the cooling requirements was determined at last by the CFD results comparison. In addition, the author analyzed the influencing factors to the performance of complex flow and heat transfer in cylinder head on the base of the best designed model, which provides the ameliorate direction for further optimum design of cylinder head and water jacket.