Frictional Niose At The Gas-solid Interface Of High-speed Train

Along with advance of scientific technology and development of civil economy, construction of domestic high-speed railway has become a new point of economic rise, such as construction of "4 length lines and 4 breadth lines" for passenger transportation and so on, which not only increases efficiency of transportation and shortens people's touring time, realizing the dream of that leaving in the morning and arriving in the evening, also makes higher frequency of intercommunion among different cities in terms of economy, culture and commerce. While the increase in speed of trains brings out the problem of severe noise; if noise is transmitted into passenger train, passenger's comfort will be severely affected; and if noise spreads abroad, the noise control along the line, such as hospitals, schools and uptowns, becomes difficult. Consequently, noise control has noteworthy value in view of long development of high-speed railway. Nowadays, research of noise mechanism and control is mostly about wheel-rail noise, in defect of research on aerodynamic noise. Because intensity of aerodynamic noise is in direct ration with running speed to the power 6, it should not be neglected in high-speed running.As the beginning of the study of high-speed train, chapter 1 introduced engineering background of high-speed railway, including characteristic, significance, development, building actuality and noise pollution. This chapter also described correlative scientific theory such as interface, fluent characteristic, and boundary characteristic at gas-solid interface, intermolecular force, acoustics, frictional noise and bionics.In chapter 2, based on theory of relative movement and boundary, laminar flow boundary model on a carriage of high-speed train was established for aerodynamics. Rate field of air flow and noise root on the carriage were studied with Matlab program. Moreover, intermolecular force is taken into account for the study.In chapter 3, on the basis of previous analysis, tiny cell is constructed on slippery boundary in the head of high-speed train. Grid meshes are measured by Gambit program, then overfall boundary model was presented in RNGκ-εmodel by Fluent program to analyze rate, pressure, shearing strength and noise in the tiny cell in microcosmic angle.In chapter 4, overfall boundary model was given in the tiny cell by Gambit program and Fluent program on the high-speed train with round texture. The effects of depth-radius ratio, area ratio, topology and scale on the rate, pressure, shearing strength and noise in the tiny cell were examined with numerical simulation.In chapter 5, overfall boundary model was proposed in the tiny cell by Gambit program and Fluent program on the high-speed train with triangle texture. The effects of direction, base-height ratio, base-depth ratio, density, topology and scale on the rate, pressure, shearing strength and noise in the tiny cell were analyzed with numerical simulation.In chapter 6, based on the micro-texture at gas-solid interface of high-speed train, the advantages and disadvantages of existing machining technique were discussed. In succession, the method of combined electrochemical-ultrasonic machining was proposed and feasibility of other correlative techniques was discussed.The last chapter is the summery of present work in this thesis and put forward other important issues that need to be studied on in the next step of scientific research.