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عدد المساهمات : 18961 التقييم : 35389 تاريخ التسجيل : 01/07/2009 الدولة : مصر العمل : مدير منتدى هندسة الإنتاج والتصميم الميكانيكى
| موضوع: رسالة ماجستير بعنوان Suppression of Vibratory Stresses in Turbine Structural Components Subjected to Aerodynamic Loading الأربعاء 18 مايو 2022, 1:47 am | |
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أخواني في الله أحضرت لكم رسالة ماجستير بعنوان Suppression of Vibratory Stresses in Turbine Structural Components Subjected to Aerodynamic Loading Author Imran Aziz 2010-NUST-MsPhD-Mech-08 Supervisor Imran Akhtar Department of Mechanical Engineering College of Electrical & Mechanical Engineering National University of Sciences and Technology Islamabad
و المحتوى كما يلي :
Table of Contents 1. CHAPTER 1 .14 1.1 Background, Scope and Motivation .14 1.1.1 Fluid Dynamics and Rotor Stator Interaction 15 1.1.2 Forced response .16 1.1.3 Computational Methods .20 1.1.4 Single Passage Modeling .23 1.1.5 Material Damping 25 1.2 Thesis Overview 28 1.3 Thesis Objectives .30 2. CHAPTER 2 .32 2.1 Navier Stokes Equations 33 2.2 Turbulence .33 2.3 Turbulence Modeling .35 2.3.1 Turbulence Modeling .35 2.3.2 The Zonal SST Model by Menter 36 2.4 Transition .38 2.5 Discretization and Solution Theory 39 2.5.1 Numerical Discretization .39 2.5.2 Discretization of the Governing Equations 39 2.5.3 Order of Accuracy .42 2.5.4 Shape Functions .42 2.5.5 Control Volume Gradients .43 2.5.6 Advection Term .44 2.5.7 High Resolution Scheme .44 2.5.8 Diffusion Terms .44 2.5.9 Pressure Gradient Term .45 2.5.10 Compressibility .45 2.5.11 Transient Term 46 2.6 Interface Modeling .47 2.7 Transient Blade Row Modeling Theory .47 2.7.1 Time Transformation Method 49 2.8 Dynamic Analysis 51 2.8.1 Solution of the Equation of Motion .54 2.8.2 Free Vibration Analysis .54 2.9 Damping Types 55 2.10 Forced Vibration Analysis .57 2.11 Direct Frequency Response Analysis .609 2.12 Modal Frequency Response Analysis 61 2.13 Energy Dissipation Method of Damping due to Coating .63 3. CHAPTER 3 .65 3.1 Geometry Detail and Distinct Features 65 3.2 Meshing Details .67 3.3 Boundary Conditions .70 3.4 Simulation Methodology 71 3.5 Grid Independence Study .71 3.6 Results and Discussions .74 3.6.1 Comparison: Steady State, Profile Scaling, Time Transformation 86 3.6.2 Time Averaged Unsteady Flow Calculations 88 3.7 Computation of Aerodynamic Loads .96 4. CHAPTER 4 .99 4.1 Technique for Finite Element Modeling 99 4.2 Preprocessing .101 4.3 Analysis 103 4.3.1 Uncoated Beam Free Vibration Analysis .103 4.3.2 Coated Beam Modal Analysis .105 4.3.3 Frequency Response Analysis of Uncoated Beams .106 4.3.4 Coated Beam Frequency Response Analysis .107 4.4 Curved Blade Analysis .109 5. CHAPTER 5 .115 5.1 Frequency Response Analysis under Concentrated Force .120 5.2 Frequency Response Analysis under Steady State Aerodynamic Loading 124 5.3 Effect of Changing the Orientation of Coating on Damping Performance of Magnetomechanical Coating 126 6. CHAPTER 6 .131 7. APPENDIX A .134 8. REFERENCES List of Figures Figure 1.1: Collar Triangle of Aero elasticity (Left), Forced Response analysis principle (right) .17 Figure 1.2: Campbell Diagram [12] 18 Figure 1.3: Summary of the analysis procedure for axial turbine blade .29 Figure 2.1: Control Volume Discretization 40 Figure 2.2: Interpolation Points in an element 41 Figure 2.3: One passage periodicity cannot be applied 48 Figure 2.4: Workaround using Standard Periodicity 48 Figure 2.5: Phase Shifted Periodic Boundary Conditions 49 Figure 2.6:Dynamic Process Environment .52 Figure 2.7: Harmonic Forced Response without damping [85] 58 Figure 2.8: Harmonic Force Response with Damping [85] .60 Figure 3.1: Axial Turbine Geometry details [90] .66 Figure 3.2: O-H Block Topology along with generated Mesh .68 Figure 3.3: Blade to Blade view of Mesh at 50% Span 69 Figure 3.4:Grid Independence of pressure envelops at mid span .73 Figure 3.5:Position of the plane 1 (first stator exit), plane 2 (rotor) and plane 3 (second stator exit) 74 Figure 3.6: Turbulence Kinetic Energy at the exit of stator 1, rotor and stator 2. 75 Figure 3.7: Mach number Contour at the first stator1, rotor and stator 2 exit 75 Figure 3.8: Absolute flow angle at the first 1, rotor and stator 2 exit .75 Figure 3.9:Pressure Contours at the hub and rotor wall in rotor domain. .76 Figure 3.10: Static Entropy at the stator 1, rotor and stator 2 exit 76 Figure 3.11: Vector plot of Vortices at first stator exit .77 Figure 3.12: Vector plot of Vortices at rotor exit .77 Figure 3.13: Vector plot of Vortices at stator 2 exit .78 Figure 3.14: Entropy contours in streamwise direction along the rotor blade 79 Figure 3.15:Mach number contours in stream-wise direction along the rotor blade 79 Figure 3.16: Contours of turbulence kinetic energy in streamwise direction along the rotor blade. 80 Figure 3.17: Time Transformation Method, Entropy Contours at 10 %, 50 %, 90 % Span .81 Figure 3.18: Time Transformation Method, Entropy Contours at the exit of stator 1, rotor and stator 2. 81 Figure 3.19:Profile Scaling Method, Blade to Blade unsteady Entropy contours (25%, 50%, 75%, and 100%) Pitch distance 82 Figure 3.20: Blade to Blade Mach number Contours (25%, 50%, 75%, 100% pitch) 83 Figure 3.21: Profile scaling method, Instantaneous entropy contours behind rotor (25%, 50%, 75%, and 100%) Pitch .83 Figure 3.22:Instantaneous entropy contours behind second stator (25%, 50, 75%, 100) Pitch 8411 Figure 3.23: Boundary layer capturing at pressure and suction side of the blade .84 Figure 3.24: Vortex Core Region, Full three dimensional Views. .85 Figure 3.25: Streamlines from Stator 1 inlet to stator 2 outlet 85 Figure 3.26: Prediction of Tip Clearance, Secondary and Horse Shoe Vortices 86 Figure 3.27:Comparison between steady and unsteady entropy contours from Inlet to outlet at10% and 50% span, First row shows steady contours, second row shows unsteady contours. 86 Figure 3.28:Comparison Entropy Span wise entropy contours, Steady State, Profile Scaling, Time Transformation at the exit of first stator 88 Figure 3.29: Comparison Entropy Span wise entropy contours, Steady State, Profile Scaling, Time Transformation at the exit of rotor blade .88 Figure 3.30:Comparison Entropy Span wise entropy contours, Steady State, Profile Scaling, Time Transformation at the exit of second stator. 88 Figure 3.31: Mach number convergence (a) at inlet of vane-1. (b) at the outlet of vane-2 89 Figure 3.32: Comparison of total pressure (absolute) at the exit of vane 1. .90 Figure 3.33: Comparison flow angle (absolute) at the exit of the vane-1 .90 Figure 3.34: Comparison of total pressure (absolute) behind the trailing edge of the rotor. 91 Figure 3.35: Comparison of flow angle (absolute), behind the trailing edge of the rotor .91 Figure 3.36: Comparison of total pressure (absolute), behind the trailing edge of the vane-2. 92 Figure 3.37: Comparison of flow angle (absolute), behind the trailing edge of the vane-2 92 Figure 3.38: (a) Predicted contours of total pressure behind the trailing edge of the first vane. (b): Predicted streamlines on suction side of the blade 94 Figure 3.39: Comparison of unsteady pressure envelopes at mid-span 95 Figure 3.40: Aerodynamic forces in X, Y and Z direction on blade suction surface 96 Figure 3.41: Aerodynamic forces in X, Y and Z direction on blade pressure surface 96 Figure 4.1: Beam Geometry and Meshing 102 Figure 4.2: Mode shapes for first four bending modes of an uncoated beam .104 Figure 4.3:Mode shapes for first four bending modes of coated beam .105 Figure 4.4:Von Mises stress and displacements for uncoated beam for third bending mode .106 Figure 4.5: Displacement and von Mises stress for First mode of uncoated Beam 107 Figure 4.6: Displacement and von Mises stress for Second mode of uncoated Beam 107 Figure 4.7: Displacement and von Mises stress for third bending mode of coated Beam 108 Figure 4.8: Comparison Chart showing % stress and displacement reduction (y axis) vs. First 3 modes (x axis) in rectangular cantilevered beam .109 Figure 4.9: Original Blade (7” x 3” x 0.34”) 109 Figure 4.10: Curved Plateμ (7” x 3” x 0.35”) 110 Figure 4.11: Isometric view of the meshed blade. 110 Figure 4.12: Third and fourth stripe modal displacements of the coated cantilevered blade 11212 Figure 4.13: The von Mises stresses in second stripe mode of the uncoated and coated turbine blade 113 Figure 4.14: The von Mises stresses in third stripe mode of the uncoated and coated turbine blade .113 Figure 4.15: The von Mises stresses in fourth stripe mode of the uncoated and coated turbine blade .113 Figure 4.16: Stress reduction vs. mode number 114 Figure 5.1:(a) Turbine structural components orientation with respect to each other (b) Mapping of fluid dynamic loads on structural nodes. 116 Figure 5.2: The von Mises stress in first mode of uncoated and coated axial turbine blade .117 Figure 5.3: The von Mises stress in second mode of uncoated and coated axial turbine blade 118 Figure 5.4: The von Mises stress in first stripe mode of uncoated and coated axial turbine blade .118 Figure 5.5: The von Mises stress in second stripe mode of uncoated and coated axial turbine blade. .119 Figure 5.6: von Mises stress (Ksi) comparison between uncoated and coated blade .120 Figure 5.7: von Mises stress (Ksi) comparison between uncoated and coated blade .121 Figure 5.8: von Mises stress in the 2nd and 3rd bending mode of the coated blade under concentrated force .122 Figure 5.9: Vibratory stress comparison in the coated blade due to aerodynamic and concentrated loading .123 Figure 5.10: % Stress reduction comparison between aerodynamic and concentrated loading 123 Figure 5.11: Displacement and Stress distribution in turbine blade for first mode under steady state aerodynamic loading .124 Figure 5.12: Displacement and Stress distribution in turbine blade for second mode under steady state aerodynamic loading .125 Figure 5.13: Displacement and Stress distribution in turbine blade for first stripe mode under steady state aerodynamic loading 125 Figure 5.14: Displacement and Stress distribution in turbine blade for second stripe mode under steady state aerodynamic loading 126 Figure 5.15: View of Magnetomechanical Coating on the top and bottom surface of the blade 127 Figure 5.16: Displacement and Stress distribution in turbine blade with coating on top surface for first mode 127 Figure 5.17: Displacement and Stress distribution in turbine blade with coating on top surface for second mode 128 Figure 5.18: Displacement and Stress distribution in turbine blade with coating on top surface for first stripe mode. .128 Figure 5.19:Displacement and Stress distribution in turbine blade with coating on top surface for second stripe mode. .129 Figure 5.20:Stress reduction comparison between the pressure side and suction side coating .13013 List of Tables Table 3-1: Geometrical Data of IST Turbine [90] 66 Table 3-2: Aachen turbine Geometrical Parameters 66 Table 3-3: Grid Points for Each Domain 70 Table 3-4: Boundary Conditions Assumed for CFD Analysis 70 Table3-5:Meshes for Grid Independence 72 Table 3-6: Flow Parameters at the Vane-1 inlet .97 Table 3-7: Flow Parameters at the Vane-1exit 97 Table 3-8: Flow Parameters at the rotor blade inlet 97 Table 3-9: Flow Parameters at the rotor blade exit .97 Table 3-10: Flow Parameters at the Vane-2 inlet .98 Table 3-11: Flow Parameters at the Vane-2 exit .98 Table 4-1: Mechanical Properties of Substrate Materials .101 Table 4-2: Mechanical Properties of Substrate Materials .101 Table 4-3: Summary for Uncoated Beam Modeling .102 Table 4-4: Steps for Coated Beam Modeling 103 Table 4-5: Natural Frequencies of first four bending modes of uncoated beam .104 Table 4-6: Natural Frequencies of first four bending modes of a coated beam 105 Table 4-7: Stress and Displacement Reduction % for first three bending modes. 108 Table 4-8:Natural Frequencies for uncoated and coated blade .111 Table 4-9: Maximum stress (Ksi) comparison of Cantilevered Blade 112 Table 5-1: Natural frequency of uncoated and coated turbine blades .117 Table 5-2: Maximum stress comparison of uncoated (Ksi) and coated axial turbine blade (Ksi) under aerodynamic loading .119 Table 5-3: Maximum stress comparison of uncoated (Ksi) and coated axial turbine blade (Ksi) under concentrated harmonic loading .121 Table 5-4: Vibratory Stress Comparison (Ksi) between Steady and Unsteady Loading 126 Table 5-5: Von Mises Stress Distribution in top coated axial turbine blade .129
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