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轴流风扇的优化设计及其对电机冷却性能的影响

发布时间:2020-11-15 04:45
   轴流风扇在许多工业应用中占有重要的地位,其主要目的是为传热和传质提供大量与旋转轴平行的气流,不同容量的轴流风扇广泛用于各种工业设备和工艺,如纺织厂、化肥工业、化工、制药以及发电等主要行业。然而,轴流风扇在大容量电动机的行业中强化传热的效果更为明显,得到广泛应用。本文介绍了空冷电机轴流风扇的计算流体动力学(CFD)模型。利用Solidworks软件建立包括风扇叶片、风扇箱、风扇轴、护罩、轮毂和旋转壁面在内的计算域物理模型并采用GAMBIT软件进行网格划分。采用ANSYS FLUENT 16软件进行数值模拟,研究了安装角度、出口压力变化以及叶片数量对轴流风扇运行性能的影响。此外,还研究了湍流模型和叶片厚度对风扇吸入的空气体积流量的影响。本文还研究了风扇出口前方不同位置处湍流强度的变化特征,试图探索风扇湍流强度变化对电机冷却效果的影响,找到风扇在电机前方轴上的最佳位置。为了保证计算结果的准确性,对完整模型和简化模型的体积流量进行了对比。本文采用有限体积法对三维湍流方程进行数值求解。结果表明,体积流量随着出口压力的增加而减小。当安装角度增加时,轴流风扇的体积流量和效率值更高,在角度为30°、风扇叶片数为19个时最高。标准SST k-ω模型和标准k-ε模型的模拟结果基本相似,但SST k-ω模型的计算精度略好于标准k-ε模型。当减小叶片厚度时,体积流量显著下降。湍流强度分析表明,风扇附近的紊流强度值较高,但线性减小到第五个监测面,然后开始增加。该研究可为轴流风扇的优化设计提供相关参考,有助于风扇的改进以提高系统的整体冷却性能。
【学位单位】:哈尔滨理工大学
【学位级别】:硕士
【学位年份】:2018
【中图分类】:TH432.1
【文章目录】:
摘要
Abstract
Chapter 1 Introduction
    1.1 Research Purpose and Significance
    1.2 International and Domestic Scope of Research
        1.2.1 Importance of Axial Flow Fan and Scope of Research
        1.2.2 The Research Scope of Numerical Analysis
        1.2.3 Scope of Research on Electric Motors
        1.2.4 Scope of CFD Analysis of Turbo-machinery
    1.3 Main Contents of the Research
Chapter 2 Theory of the Axial Flow Fan
    2.1 Overview of Fans
    2.2 Difference between Fans, Blowers and Compressors
    2.3 Axial Flow Fans
        2.3.1 Types of Axial Flow Fan
    2.4 Motion and Velocity Triangle
        2.4.1 Motion of a Fluid over a Blade
        2.4.2 Triangle of Velocity
    2.5 Lift Theory of Axial Flow Fan
        2.5.1 Geometric Parameters of the Airfoil
        2.5.2 Aerodynamic characteristics of Individual and Connected airfoil
        2.5.3 Equation of Energy
        2.5.4 Selection of Fan
    2.6 Performance of Axial Flow Fan
        2.6.1 Theoretical Analysis of the Factors Affecting the Fan Performance
    2.7 Summary
Chapter 3 Computational Method-Computational Fluid Dynamics
    3.1 Overview of Computational Fluid Dynamics
    3.2 Advantages of Computational Fluid Dynamics
    3.3 Applications of Computational Fluid Dynamics
    3.4 Computational Fluid Dynamics Basic
        3.4.1 Flow Physics Modeling
        3.4.2 Turbulence Closure
        3.4.3 Numerical Simulation Technique
    3.5 Governing Equations of Computational Fluid Dynamics
        3.5.1 Mass Conservation Equation
        3.5.2 Conservation Equation of Momentum
    3.6 Turbulence
    3.7 Discretization Method
    3.8 Summary
Chapter 4 Physical Model and Mesh Generation
    4.1 Overview of Solidworks
    4.2 Establishment of Physical Models
        4.2.1 Blade or Airfoil
        4.2.2 Twist of a Blade
        4.2.3 Number of blades
    4.3 Overview of Meshing
    4.4 Types of Mesh
        4.4.1 Structured Grids
        4.4.2 Unstructured Grids
    4.5 Mesh Generation Process
    4.6 General Measures of Mesh Quality
    4.7 Commercial Meshing Software
    4.8 Meshing Flow Diagram
    4.9 Import and Repair of the Geometry
    4.10 Mesh Generation and Independence Test
    4.11 Summary
Chapter 5 Results and Discussion
    5.1 Overview
    5.2 Steps in Solving CFD Problem
    5.3 Computational Method and Boundary Conditions
        5.3.1 Turbulence Models and its Selection
        5.3.2 Overview of Shear-Stress Transport (SST) k-ω Model
        5.3.3 Detail of Equations of Shear-Stress Transport (SST) k-ω Model
    5.4 Flow in a Rotating Reference Frame
        5.4.1 Introduction
        5.4.2 MRF Model
        5.4.3 SRF Model
        5.4.4 Convergence
    5.5 Discussion on Results
        5.5.1 Relation of Pressure and Volumetric Flow Rate
        5.5.2 Relation of Pressure and Efficiency
        5.5.3 Effect of Installation Angle on Volumetric Flow Rate and Efficiency
        5.5.4 Pressure and Velocity Contours on the Blades
        5.5.5 Effect of Number of Blades on Volumetric Flow Rate
        5.5.6 Comparison of Turbulence Models
    5.6 Summary
Chapter 6 Effect of Turbulence Intensity on the Cooling Performance of the Motor
    6.1 Overview
    6.2 Effect of Physical Model on Numerical Analysis
    6.3 Effect of Blade trimming on the Volumetric Flow Rate
    6.4 Effect of Turbulent Intensity on Fan and Motor
        6.4.1 Discussion on Turbulence Intensity
        6.4.2 Effect of Turbulence Intensity
        6.4.3 Effect of Turbulence Intensity on Heat Transfer of the Motor
    6.5 Accuracy of Numerical Results
    6.6 Summary
Conclusion
References
Academic Achievements
Expression of Thanks

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