Constructing The Shape Of Subway Head Based On NURBS Theory And Analysis Aerodynamic Characteristics

With the development of urbanization, there are more and more people in city and the problem of urban traffic congestion becomes more and more serious. The subway system can be a good solution to urban traffic pressure, so many cities are beginning to build subway. It is expected that there will have more than 45 cities built subway in China by 2020. As the main component of the subway system, subway train bear the important task of transporting passengers. The capability for subway operating has been improved by gradual increasing the speed of subway. So, it is not only effective to reduce the air resistance and improve the running speed of subway train, but also to reduce operation cost through the design of the reasonable shape of the subway.Based on the NURBS curve and numerical simulation of flow field,in this paper analyzes the shape design and aerodynamic performance of subway train by several different research methods and draws some conclusions and basis which have certain reference for the shape of the subway train head. This paper mainly carries on the following three aspects:(1) This paper constructs three schemes of subway train by means of CATIA software. The first scheme references to existing models; the second scheme optimize the local transition surface of first scheme; the third scheme construct a streamlined head by absorbing the excellent design of high speed train. In the design process, the NURBS curve of the main outline of the schemes is optimized and the smoothness of train head surface curve is analyzed through the light type inspection.(2)This paper does flow field numerical simulation to the three schemes by using FLUENT software. It can accurately capture the distribution of the flow field by adding the boundary layer to the train body. According to three common conditions of subway train, the tree schemes are analyzed respectively and it can achieve the effective contrast between the schemes. The results of comparison shows that the maximum static pressure, the maximum dynamic pressure of the scheme with better streamline decrease significantly. Especially, with the improvement of working conditions, the effect of streamline design is more obvious.(3)The air resistance coefficient of the train head of the three schemes is obtained by calculating the results of numerical simulation of flow field. The results show that the air resistance coefficient of the first scheme is 0.6, the second scheme is 0.55, the third is 0.35. The results can be used in the design of the head shape of subway train.For the low-speed subway train lines, it can reduce the air resistance coefficientthrough local optimization of the existing models; for the high-speed subway train lines, it can greatly reduce the air resistance coefficient through the streamlined design. It provides a certain basis for the design of the shape of subway train head.