| In recent years, the number of car ownership in China not only large and maintain rapid growth rate. The resulting environmental problems such as air and noise pollution is also more and more get people’s attention, Moreover, but now people all aspects of performance comfortable, etc. To solve the above problem, one important task is to design a high quality exhaust system, one important task is to design a high quality exhaust system, which can not only relieve air and noise pollution and other environmental problems caused by automobile engines, but also in improving the performance of automotive comfort also has a very important role. In addition, in the face of the challenge of the leading car companies abroad serious national car companies want to have a foothold to independent intellectual property rights must be constantly innovation, form their own system of vehicle design and has a quick response to market demand, makes every effort in the shortest time to produce to meet the market demand of high quality products. Therefore, The national car companies in our country start late, research and development of technology and management experience are relatively backward situation, the combination of reverse engineering and CAE analysis technology has been widely applied in the field of automotive design.In this paper, Combining with the actual project, the first part, the use of three-dimensional laser scanner on the benchmark vehicle exhaust system for physical scan the surface to obtain a three-dimensional point cloud data. Using three-dimensional CAD modeling software CATIA reverse engineering module for data preprocessing, and then deal with good data for 3 d modeling, due to the exhaust system is a typical three-dimensional bend class thin-walled structures, thus this article focuses on the reverse of this kind of problem modeling method, the final combination chassis hard point arrangement, get the final three-dimensional modulus exhaust system.The second part of the application of large commercial CFD analysis software ANSYS FLUENT software for the flow field in the cold end of the pressure field, temperature field, velocity field and turbulent kinetic energy field is simulated, and the simulation results are analyzed theoretically, found that the reason for the pressure loss, energy loss and the turbulent kinetic energy is mainly by the main away inside into, the cannula insertion depth, baffle plate position, and number of pores on them caused. According to the results of the analysis and combined with relevant theoretical knowledge, to optimize the retrofit design, the main measures to shorten the inlet and the outlet tube inside the entrance of depth, at the same time and in order to speed the transition section due to mutations caused watershed surge phenomenon of vortex produced within the outlet tube into a trumpet-shaped mouth, and then the flow field in the structure and improved in the CFD analysis. By comparison, the improved, reducing the jet stream in the main consumer, as well as generate eddy swirling flow, so that the gas flow pattern a variety of sports tend to be relatively stable state, eased for potential nuclear, interference, collisions and other reason causes resistance increases, energy loss condition. The improved to fulfill the requirements of the project. Finally, the application of large-scale dynamics analysis software NASTRON on the exhaust system with constraints modal analysis. obtained the relationship between natural frequency and natural frequency of the vehicle and find the vibration point the location of the smaller for the entire system provides a theoretical reference for the arrangement of the lug.By reverse engineering and finite element analysis techniques in combination, efficient eventually got a similar to benchmarking car without infringement, and to advance beyond the original models on performance of the new exhaust system. And this method also for the future design of muffler provides a new reference. |
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