叶轮流固耦合界面不匹配网格的数据传递

发布时间：2018-10-10 15:08

【摘要】：离心式压缩机叶轮是将机械能传给气体,以提高气体能量的唯一元件。其运行时和气体的相互作用是一个典型的流固耦合问题。要对叶轮进行准确的力学分析,必须考虑气动载荷的影响。然而用数值方法对叶轮进行流固耦合分析,流体域划分的网格密度往往远大于固体域,导致耦合界面上网格不匹配的情况。在这样的网格间并不能直接传递各个场的数据,需要引入耦合算法实现数据传递。近些年来,对于耦合方法的研究已经比较系统,提出了许多种耦合算法。本文将最邻近点插值法(NN)、快速映射法(FPA)和径向基函数(RBF)插值算法等三种方法引入到叶轮的流固耦合分析中,分别根据其基本原理推导出耦合矩阵。推导过程显示,最邻近点插值法原理简单,而径向基函数数学概念清晰,两者都十分有利于编程计算。在MATLAB平台上,编制了对应的耦合计算程序。此外,有限元分析软件ANSYS中含有基于快速映射法的内部函数,利用此函数,论文通过ANSYS-APDL脚本语言编制了快速映射法的插值计算程序。为了验证上述三种算法的精确度,分别构造了具有解析解的二维和三维插值算例,用MATLAB和ANSYS-APDL对其进行求解,并将结果与解析解进行比较。对比证明,三种方法中,RBF插值法的计算结果最精确,其与解析解的相对误差大多分布在10-3～10-5之内,精度上完全满足工程应用的需求。需要注意的是,目前对不匹配网格耦合算法的研究大多只基于简单的算例,很少有人将算法应用到复杂模型的流固耦合分析中。而大型耦合模型往往存在耦合面复杂,节点数据众多,计算量极大等问题。如何在保证精度的前提下又能提高计算效率,一直是工程应用中急需解决的问题。本文以某大型离心式压缩机闭式叶轮的单向松耦合分析为实例,新增前、后处理模块完善了编制的计算程序,并且对于叶轮耦合界面求解量巨大的问题,找到了一种简便、精确又能极大提高计算效率的处理方法,很好的完成了数据传递。这一整套数据耦合方法适用范围广,可灵活运用于大型流固耦合甚至任意场的耦合分析中。本文受国家重点基础研究发展计划项目(2011CB706504)和沈阳鼓风机集团有限公司资助。
[Abstract]:Centrifugal compressor impeller is the only component that can transfer mechanical energy to gas to improve gas energy. The interaction between operation time and gas is a typical fluid-solid coupling problem. In order to analyze the impeller accurately, the effect of aerodynamic load must be considered. However, the numerical method is used to analyze the fluid-solid coupling of impeller. The density of meshes in fluid domain is much larger than that in solid domain, which leads to the mismatch of meshes on the coupling interface. The data of each field can not be transferred directly between these meshes, so it is necessary to introduce the coupling algorithm to realize the data transfer. In recent years, the study of coupling methods has been systematic, and many coupling algorithms have been proposed. In this paper, the nearest neighbor point interpolation method (NN), fast mapping method (FPA) and radial basis function (RBF) interpolation algorithm are introduced into the fluid-solid coupling analysis of impeller, and the coupling matrix is derived according to their basic principles. The derivation shows that the nearest neighbor interpolation method is simple and the radial basis function mathematical concept is clear. Both of them are very helpful for programming calculation. On the MATLAB platform, the corresponding coupling calculation program is developed. In addition, the finite element analysis software ANSYS contains the internal function based on the fast mapping method. Using this function, the interpolation calculation program of the fast mapping method is compiled by ANSYS-APDL script language. In order to verify the accuracy of the above three algorithms, two and three dimensional interpolation examples with analytical solutions are constructed, and solved by MATLAB and ANSYS-APDL, and the results are compared with the analytical solutions. It is proved by comparison that the RBF interpolation method is the most accurate of the three methods, and the relative error between the method and the analytical solution is mostly within 10 ~ (-3) ~ 10 ~ (-5), which fully meets the requirement of engineering application. It should be noted that most of the current researches on mismatched grid coupling algorithms are based on simple examples and few people apply the algorithms to the fluid-solid coupling analysis of complex models. However, there are many problems in large coupling models, such as complex coupling surface, large number of node data and large amount of computation. How to improve the calculation efficiency on the premise of ensuring accuracy has always been an urgent problem in engineering application. In this paper, the unidirectional loose coupling analysis of the closed impeller of a large centrifugal compressor is taken as an example. The calculation program is perfected by the post-processing module before adding, and a simple and convenient method is found for solving the problem of the impeller coupling interface. Accurate and can greatly improve the computational efficiency of the processing method, a good completion of the data transfer. This set of data coupling methods can be used flexibly in the coupling analysis of large fluid-solid coupling and even arbitrary fields. This paper is supported by the National key basic Research and Development Program (2011CB706504) and Shenyang Blower Group Co., Ltd.
【学位授予单位】：大连理工大学
【学位级别】：硕士
【学位授予年份】：2012
【分类号】：TH452

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