Analysis On The Performance And Operation Optimization Of Cabin Thermal Cooling System In Passenger Coach

With the progress of science and technology and the development of the society and automobile industry, people improve their demand to the performance, stability and economy of automobile step by step. In order to improve the comprehensive performance of automobile, the manufacturers have designed the structure of automobile more and more complex, and the layout of the engine cabin more compact. The engine cabin is more and more "crowded" which makes the aerodynamic characteristics of cabin worse. In some cases there may be the problem of insufficient heat dissipation. Because of load and environment factors, automobile engine sometimes work under very bad conditions, which makes heat far more than that under the general condition in the engine cabin. If the air in the cabin flows bad, the cooling system is likely to be "failure", not able to take the heat generated by the engine away in time, resulting in heat accumulation and reduction of life of the engine and related spare parts. So we must try to avoid overheat in engine cabin. In the process of vehicle design, a comprehensive analysis and evaluation should be carried through on the thermal environment and thermal performance of the engine cabin, and then its internal flow field characteristics can be optimize according to the evaluation results.·Based on the basic theory of computational fluid dynamics and referencing to the related literature at home and abroad, this thesis takes Dandong Huanghai DD6121S18 coach as research object, uses computational fluid dynamics(CFD) software STAR-CCM+ and the appropriate grid type, sets turbulent boundary conditions and solving method, uses the post-processing module to output visual flow field and temperature field in the engine cabin.·The contents are as follows:(1) Introducing the steps and advantages of CFD, the basic control equations of fluid dynamics and heat transfer, numerical discrete method, turbulence model and so on, for analogue simulation.(2) Building the cabin model and full coach model, using meshes, heat exchanger model, fan model and boundary conditions for applying software and analyzing the working of the engine, studying the analogue simulation and the data.(3) Researching the reason of overheat of engine based on the theory studying and data analysis, calculating the flow field of engine cabin and the temperature field of engine under general working condition.(4) Referring with the structural features of Dandong Huanghai DD6121S18 coach, improving fan cowl, radiator deflector shields and arched Bulge surface to reducing the temperature in engine cabin.