Study On Drag Reduction Of High-speed Train Based On Morphological Bionic

With the development of high speed railway and the increase of the train speed, the interaction between train and air fluctuates violently, and drag reducing problem becomes an important issue of the research. There is a close relationship between train shape and aerodynamic resistance. Taking the high speed train as the objective, the research on drag reduction of bionic form using a bionic design through the method of numerical simulation is conducted in this paper.Four typical fast animals have been chosen as the bionic prototype, the bionic train model is established by extracting biomimetic elements. On account of the 3D steady and incompressible Navier-Stokes equation, RNG κ-ε turbulence model and computational fluid dynamics software FLUENT, the high-speed train bionic geometric model and calculation model are established based on the CRH train. The aerodynamic performance in the open air of different bionic shapes is calculated. The result shows that the head car aerodynamic resistance of different bionic models except the shark train is smaller than the CRH train. It means that bionic design has advantages for drag reduction. Without considering the structures of under car such as the bogie, bionic models have no upward lift force. In order to investigate the drag reduction of the bionic model, CAD software is used to divide the streamline head into several sections along the direction of the car model (i.e. length direction), the linearized curve of sectional area along the length direction is obtained. It found that the higher level of linear the bionic type area along the length direction, the smaller aerodynamic resistance.The calculation model of a train in cross wind is established. The overturning moment is the most dangerous factor of crosswind safety. Bionic design head car is significantly less than that of the CRH train. And the crosswind aerodynamic performance of the bionic train is better than that of CRH without considering the bogie.Based on the turbulent kinetic energy and pressure distribution, the bionic model was weakened. With the analysis of the above model, the turbulent kinetic energy of flow field behind the train decreases. The positive pressure area of the head car and negative pressure area of the tail car decrease, which make the pressure resistance decrease obviously. Considering the bogie region, an engineering improvement of the train at the speed of 350km/h is conducted. The influence of streamline length on flow performance of high-speed trains researched,14m is appropriate to be the streamline length of the super high-speed train. Considering bogie region, the engineering improvement of the train have been made at the speed of 600km/h, in order to satisfy the engineering requirement, such as the modeling technology and practical application.