【作者】 高殿荣；

【导师】 王益群；

【作者基本信息】 燕山大学 ， 机械电子工程， 2001， 博士

【摘要】 本文在参阅大量国内外有关流体动力技术、计算流体力学、流场的数值计算方法、流场实验可视化技术、计算机数字图像处理技术等相关资料的基础上，推导确定了复杂流道和液压阀中流体流动的数学模型，首次用有限元方法对液压技术中各种异形断面流道、各种复杂流道和液压阀内部流道等的流场进行数值模拟，并将计算结果以可视化的图形图像形式给出，在此基础上定性分析了流场结构（速度、流线、流动的分离与再附壁，旋涡的产生与消失等）与噪声、能量损失的关系。同时对流场进行DPIV（Digital Particle Image Velocimetry）实验可视化研究，验证了数值计算的正确性。为设计高效率、低能耗、低噪声的液压阀和流体管道系统奠定了基础，具有重要的理论意义和实际应用价值。 第一章综述了液压技术发展趋势及本科题的意义、来源，介绍了液压技术中液体在复杂流道中的流动问题，简单叙述了计算流体力学中的各种数值计算方法，较为详细地介绍了计算流体力学在液压技术中的应用现状，论述了流场数值计算可视化技术，概述了流场实验可视化技术中的各种方法，阐述了计算机数字图像处理在流场实验可视化中的应用，确定了本文的主要研究内容。 第二章建立了支配异形断面流道内流体流动的数学模型，并用有限元方法进行离散。对包括等边三角形断面流道、矩形断面流道、梯形断面流道、半椭园形断面流道等各种异形断面流道，在不同流动条件下断面上的速度、流量等参数进行数值计算，并与有关的解析结果相比较，证明了所用方法的正确性。为工程实际中设计和选择异形断面流道提供依据。 第三章简述了用有限元方法求解流体流动问题时，可以采用的几种不同形式的数学模型，并简要说明了各种形式的特点。然后从连续性方程和Navier-Stokes方程出发，推导出无量纲流函数-涡量式。分别介绍了当采用三节点三角形单元和四节点等参四边形单元时，如何对单元进行有限元分析，以及如何计算各相关系数等。这是能否用有限元方法正确描述流场的关键。 第四章分析研究了在用有限元方法求解流函数—涡量式时，如何确定进口处、出口处，上、下壁面处，角点处等流函数和涡量的边界条件，特别是涡量边界条件。对几种不同的涡量边界条件的确定方法进行了讨论，并以平行平板管道中的流动为例进行计算，以便确定它们的精度。在此基础上计算方腔驱动流动和后台阶流动，并讨论进、出流边界条件对后台阶流动的影响。这是进一步研究液压技术中各种复杂流道流场的前期和基础工作。 第五章针对液压技术中常见的断面突然扩大管道、断面突然缩小管道、液压集成块内部的复杂流道、各种节流孔口（包括薄壁孔口、偏置细长孔口）等的流场进行有限元数值模拟，并给出流场的数值计算可视化图形图像，在此基础上定性分析流体噪声、能量损失与流场结构之间的关系等，并提出相应的改进措施，为分析管道系统的能量损失和降低噪声奠定理论基础。 第六章用有限元方法对液压传动与控制中最常见的两种结构形式的液压阀—液压滑阀和液压锥阀流场进行数值预报，给出不同开口度和不同结构尺寸下流场结构的可视化图像，定性分析涡旋的产生对流体噪声及能量损失可能产生的影响，并对阀的流道结构进行改进。 第七章建立流场DPIV实验可视化系统，制做突然扩大流道模型，外流式锥阀 燕山大学工学博士学位论文模型和滑阀模型，并利用粒子图像测速技术对模型的速度场进行测量。利用图像处理分析软件对实验结果进行计算机数字图像处理，给出模型流场的实验可视化图像，并与有限元计算结果进行对比分析，对导致数值计算与实验可视化之间出现误差的各种可能原因进行了分析，便于今后进一步研究中加以注意和改进。更多还原

【Abstract】 In this article, based on reading and studying a great number of references about fluid dynamic technique, computational fluid mechanics, numerical computing methods of flow field, visualization in science computing, experimental visualization in fluid flow computer digital image processing technique etc, the mathematical models which governing the flow in complicated conduits and hydraulic valve have been derived, the finite element method is applied to simulate the flow field of various non-circular cross- section duct, various complicated channel and hydraulic valve, the computing results are given in the form of visualized pictures or images, based on these results, the relationship between the flow field structure and the flow noise, energy loss are analyzed quantitatively. At the same time, the experimental visualization - DPIV(Digital Particle Image Velocimetry) is also carried out, and it proves the computing result is correct. It has important significance for us to design hydraulic valves and pipeline systems which are high in efficiency, low in energy loss, low in noise. In chapter 1, hydraulic technique and its developing trends are summarized, the flow problems in complicated flow channel of hydraulic technique are introduced. Various numerical methods of computational fluid dynamics are present briefly, the present situations of application of computational fluid dynamics in hydraulic technique are described in detail. The computational visualization technique of flow field is outlined, various flow field experimental visualization methods are surveyed. The application of computer digital image processing technique in experimental visualization of flow field is discussed. The main researching contents are determined. In chapter 2, the mathematical model which governs the flow in non-circular cross- section channel is established, FEM(Finite Element Method)is used to discrete the equations. The cross-section parameters such as velocity and flowrate at different flow conditions for various non-circular duct such as equilateral triangle channel, rectangle channel, terrace channel, semi-elliptical channel etc are calculated. Parts of the numerical results are compared with the analytical results, it shows that the numerical method used here is correct. In chapter 3, several different kinds of mathematical models and their characteristics when we solve the flow problems with FEM are presented. From continuity equation and Navier-Stokes equation, non-dirnensionalized stream function ?vorticity equations is derived. Ho~v to analyze the elements with FEM and how to calculated the related coefficients when adopting three nodes triangle elements and four nodes quadrilateral elements respectively is proposed, which is the key for computing the flow field correctly. In chapter 4, how to determine the boundary conditions of stream function and vorticity, especially vorticity boundary conditions at inlet, outlet, up wall, down wall and the corner are studied when using FEM to solve the stream function-vorticity equation. Several approaches of determining the vorticity boundary condition are discussed. The flow in parallel plate channel is computed as an example to verify their accuracy. Based on above analysis, the flow in square cavity and backward-facing step is investigated, the influence of inlet and outlet boundary conditions on backward facing step are also examed. In chapter 5, the flow field of several different flow channels frequently used in hydraulic technique such as sudden expansion channel, sudden contraction channel,更多还原