【作者】 吴中雷；

【导师】 刘传绍；

【作者基本信息】 河南理工大学 ， 机械工程， 2011， 硕士

【摘要】 随着现代工业生产的迅速发展,机器对机械产品零部件表面性能的要求越来越高,同时由磨损与和腐蚀而引起的能源材料消耗也难以估量。采用有效的表面工程技术加强和修复各种零件表面是有效的措施,能够节约成本、提高零件使用寿命、减少环境污染等。冷喷涂技术是一项既经济又实用的喷涂技术,它用于材料的表面涂覆,可以改善和提高材料的表面特性,最终能提高产品表面的质量。冷喷涂实现了低温状态下的金属涂层沉积,该工艺对粉末颗粒无热影响,形成的涂层残余应力低,无氧化,涂层性质没有发生变化。本文对冷喷涂技术中最关键部分—冷喷涂喷枪内部流场采用商用FLUENT软件进行了数值模拟,在对结果进行比较分析的基础上,又研究了喷枪内部结构参数对气固两相流的特性的影响。结果表明：影响喷管内流场的参数的有入口气体压力、入口气体温度、颗粒粒径以及喷管内部结构形貌等。入口气体压力和温度越高,则出口压力和温度越高；粒径越大,颗粒加速性能越差；喷管收敛半角在42°时气固两相流所获得的速度增量最大；扩张角越小,喷管出口速度的粒子速度越大；喷枪出口形状影响着有效喷涂面积的大小；增大扩张段后的直管长度能使粒子出口速度更高等。本文对喷管内部结构进行了一定程度的优化,通过对比优化前和优化后的喷管数值模拟结果,得出结论：优化后喷管所获得的出口速度是所有模拟结果中最高的。更多还原

【Abstract】 With the rapidly development of modern industrial production, the surface of machine parts and components of mechanical products have become increasingly demanding performance. At the same time, the consumption of energy materials which caused by the corrosion and wear is immeasurable. Using the effective surface engineering technologies to strengthen and repair the surface of the part is a good way .the advantage is that it can save costs, inprove part service life and reduce environmental pollution etc.Cold spray technology is very economic and practical. It is used for surface coating materials, which can improve and enhance the surface properties of materials. And the ultimate aim is improving the quality of the product surface. The cold spray technology achieved the deposition of metal coatings under the low temperature. The process has no heat-affected to the powder particles, the coatings has low residual stress and no oxidation, and does not change the materials nature.In this thesis, a commercial fluent software is used to simulate the internal flow field of spray gun which is the most critical parts in cold spray technology.Compared with the results based on the analysis, studied the internal structure parameters of the spray on the characteristics of gas-solid flow.The results show that:the parameters which influence the internal flow field are inlet gas pressure, inlet gas temperature, particle size and morphology of the internal structure of the nozzle. The higher the inlet gas pressure and temperature are, the higher the outlet pressure and temperature are; the big the particle size is, the worse the particle acceleration is; When the nozzle convergence half-angle is 42°, the speed incremental which obtained by the two-phase flow is maximum; The smaller expansion half-angle is, the bigger the nozzle exit particle velocity is; the export shape of the spray gun effective the size of the spray area; Increasing the length of straight pipe after the expansion segment can export a higher particle velocity. The internal structure of the nozzle is optimized to a certain degree. By comparing the simulation in the nozzle before and after optimization, get the results:the exit velocity of nozzle after optimization is the highest among all the simulation results.更多还原