軸流風(fēng)扇在許多工業(yè)應(yīng)用中占有重要的地位,其主要目的是為傳熱和傳質(zhì)提供大量與旋轉(zhuǎn)軸平行的氣流,不同容量的軸流風(fēng)扇廣泛用于各種工業(yè)設(shè)備和工藝,如紡織廠、化肥工業(yè)、化工、制藥以及發(fā)電等主要行業(yè)。然而,軸流風(fēng)扇在大容量電動機的行業(yè)中強化傳熱的效果更為明顯,得到廣泛應(yīng)用。本文介紹了空冷電機軸流風(fēng)扇的計算流體動力學(xué)(CFD)模型。利用Solidworks軟件建立包括風(fēng)扇葉片、風(fēng)扇箱、風(fēng)扇軸、護罩、輪轂和旋轉(zhuǎn)壁面在內(nèi)的計算域物理模型并采用GAMBIT軟件進(jìn)行網(wǎng)格劃分。采用ANSYS FLUENT 16軟件進(jìn)行數(shù)值模擬,研究了安裝角度、出口壓力變化以及葉片數(shù)量對軸流風(fēng)扇運行性能的影響。此外,還研究了湍流模型和葉片厚度對風(fēng)扇吸入的空氣體積流量的影響。本文還研究了風(fēng)扇出口前方不同位置處湍流強度的變化特征,試圖探索風(fēng)扇湍流強度變化對電機冷卻效果的影響,找到風(fēng)扇在電機前方軸上的最佳位置。為了保證計算結(jié)果的準(zhǔn)確性,對完整模型和簡化模型的體積流量進(jìn)行了對比。本文采用有限體積法對三維湍流方程進(jìn)行數(shù)值求解。結(jié)果表明,體積流量隨著出口壓力的增加而減小。當(dāng)安裝角度增加時,軸流風(fēng)扇的體積流量和效率值更高,在角度為30°、風(fēng)扇葉片數(shù)為19個時最高。標(biāo)準(zhǔn)SST k-ω模型和標(biāo)準(zhǔn)k-ε模型的模擬結(jié)果基本相似,但SST k-ω模型的計算精度略好于標(biāo)準(zhǔn)k-ε模型。當(dāng)減小葉片厚度時,體積流量顯著下降。湍流強度分析表明,風(fēng)扇附近的紊流強度值較高,但線性減小到第五個監(jiān)測面,然后開始增加。該研究可為軸流風(fēng)扇的優(yōu)化設(shè)計提供相關(guān)參考,有助于風(fēng)扇的改進(jìn)以提高系統(tǒng)的整體冷卻性能。
【學(xué)位單位】：哈爾濱理工大學(xué)
【學(xué)位級別】：碩士
【學(xué)位年份】：2018
【中圖分類】：TH432.1
【文章目錄】：
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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