钢轨异型坯高压水除鳞过程中冲击及换热特性研究

发布时间：2018-01-07 14:41

本文关键词：钢轨异型坯高压水除鳞过程中冲击及换热特性研究　出处：《燕山大学》2015年硕士论文　论文类型：学位论文

【摘要】：钢轨的表面质量、平直度、强度等因素决定着钢轨的使用性能和寿命。尤其是在高速铁路的应用方面,为保证铁路系统安全、稳定运行,对钢轨的制造精度和表面质量提出了更高的要求。现代钢轨的生产主要采用的是万能轧制的方法,在万能轧制的过程中,对钢轨异型坯进行高压水除鳞是必不可少的一步。除鳞效果的好坏,直接影响着钢轨的万能轧制过程,进而影响整个钢轨产品的质量。所以本文旨研究在钢轨除鳞过程中的一些特性,从理论上分析其冲击和换热的情况。本文首先用数值模拟的方法解决了钢轨异型坯在受高压水冲击作用下的除鳞压力的分布问题。由于钢轨断面形状复杂,冲击受力情况难以预测,实验法存在着较大的局限性。我们通过模型的合理简化利用Fluent软件由浅入深地分析钢轨异型断面不同部分的冲击压力分布。总的来说,这种压力分布在喷嘴中心处最大,向边缘处逐渐减小;同时受断面形状和喷嘴布置情况影响较大。其次,本文采用同样的模型并开启能量方程,研究该物理过程中的换热性能。借助传热学的基本理论和数值模拟的方法,得到了钢轨异型坯表面附近的温度场分布并分析了其形成原因。温度场的分布和压力场分布正好相反,由于射流中心处的换热剧烈,所以中心处的温度最低,向两侧逐渐升高;受断面形状和喷嘴布置影响更加明显。最后,作者研究了一种简单的换热系数求解模型。利用钢轨表面以下深度为2mm处的测点温度变化曲线,通过C语言编程求解钢轨表面的换热系数分布。换热系数和冲击压力部分情况类似,冲击压力越大的地方换热越剧烈,其换热系数也就越大。同时,这一过程受时间变化影响较大,我们可以合理的选取时间步长以保证求解精度。
[Abstract]:The surface quality, flatness and strength of rail determine the performance and service life of rail, especially in the application of high-speed railway, in order to ensure the safety and stability of railway system. The manufacturing precision and surface quality of rail are required higher. The main method of modern rail production is universal rolling, in the process of universal rolling. High pressure water descaling is an essential step for the special slab of rail. The effect of descaling has a direct impact on the universal rolling process of rail. And then affect the quality of the whole rail product, so this paper aims to study some characteristics in the process of rail descaling. In this paper, firstly, numerical simulation is used to solve the problem of the descaling pressure distribution of rail special-shaped billet under the action of high pressure water shock. The shape of rail section is complex. The impact force is difficult to predict. Through the reasonable simplification of the model, we use Fluent software to analyze the impact pressure distribution of different parts of the abnormal section of rail from shallow to deep. The pressure distribution is maximum at the center of the nozzle and gradually decreases to the edge. At the same time, it is greatly affected by the shape of the section and the configuration of the nozzle. Secondly, the same model is adopted and the energy equation is opened. The heat transfer performance in the physical process is studied by means of the basic theory of heat transfer and the method of numerical simulation. The distribution of temperature field near the surface of the slab is obtained and the reason is analyzed. The distribution of temperature field is opposite to that of pressure field. The temperature at the center of the jet is the lowest because of the intense heat transfer at the center of the jet. Increasing to both sides; The influence of section shape and nozzle arrangement is more obvious. Finally, the author studies a simple heat transfer coefficient solution model. The temperature change curve of measuring points with depth of 2 mm below the surface of rail is used. The distribution of heat transfer coefficient on rail surface is solved by C language programming. The heat transfer coefficient is similar to that of impact pressure. The greater the impact pressure, the more intense the heat transfer coefficient is. At the same time, the higher the impact pressure is, the greater the heat transfer coefficient is. This process is greatly affected by the time change, we can reasonably select the time step to ensure the accuracy of the solution.
【学位授予单位】：燕山大学
【学位级别】：硕士
【学位授予年份】：2015
【分类号】：TG335

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