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Development of Phosphor Thermometry Systems for Use in Development Gas Turbine Engines

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Development of Phosphor Thermometry Systems for Use in Development Gas Turbine Engines Development of phosphor thermometry systems for use in development gas turbine engines A thesis submitted to the University of Manchester for the degree of Doctor of Engineering in the faculty of Engineering and Physical Sciences 2011 Ashiq Hussain Khalid School of Mechanical, Aerospace and Civil Engineering Faculty of Engineering and Physical Sciences University of Manchester A. Khalid Contents Contents 2 List of Tables 6 List of Figures 8 Nomenclature 18 Abstract 22 Declaration 23 Copyright Statement 23 Acknowledgements 24 About the Author 25 1 INTRODUCTION 26 1.1 Overview of the Engineering Doctorate Programme 26 1.2 Background 27 1.3 Aims and Objectives 27 1.4 Thesis Structure 28 2 MOTIVATIONS FOR PHOSPHOR THERMOMETRY IN AERO-ENGINES 30 2.1 Temperature measurement in aero-engines 30 2.1.1 Characterisation of Engine Sensors Types 30 2.1.2 Research into improved engine efficiency 32 2.1.3 The role of accurate temperature measurement 35 2.1.4 Verification / Design tool 38 2.1.5 Health Monitoring / Engine Control 38 2.1.6 Summary 39 2.2 Review of the existing methods for surface temperature measurement inside aeroengines 39 2.2.1 Introduction 39 2.2.2 Thermocouples and RTDs (contact sensors) 39 2.2.3 Radiation Pyrometry 41 2.2.4 Thermal Paints and Thermal Melts 43 2.2.5 Summary 44 2.3 Capability shortfalls, gaps & requirements analysis 47 3 LUMINESCENCE THERMOMETRY 57 3.1 Introduction 57 3.2 Historical Context 57 3.3 Principles of Luminescence 59 3.3.1 Generic Luminescence Behaviour 59 3.3.2 Luminescence in Phosphors 62 - 2 - A. Khalid 3.4 Different response modes 66 3.4.1 Introduction 66 3.4.2 Intensity Mode 67 3.4.3 Intensity Ratio 68 3.4.4 Temporal Analysis 71 3.4.5 Line shift/width method 78 3.4.6 Absorption/Excitation band analysis 78 3.5 Other factors 79 3.5.1 Introduction 79 3.5.2 Activator concentration 79 3.5.3 Particle Size 80 3.5.4 Oxygen and Pressure 81 3.6 Generic phosphor thermometry system 82 3.6.1 Introduction 82 3.6.2 Emission Detection 83 3.6.3 Excitation Sources 87 3.7 Consideration factors inside an engine environment 91 4 FIBRE OPTIC LASER DELIVERY CONSIDERATIONS 96 4.1 Introduction 96 4.2 Consideration Factors and Damage Mechanisms 96 4.2.1 Gas Breakdown 97 4.2.2 Fibre Selection for UV transmission 98 4.2.3 Thermal Tolerance 99 4.2.4 End face preparation 100 4.2.5 Loss/damage in bends 101 4.2.6 Solarisation Effects / Luminescence in the fibre 101 4.3 Experimental Setup 102 4.3.1 Fibre Preparation 103 4.3.2 Beam and Launching conditions 104 4.3.3 Energy density, fluence, peak powers and power densities 106 4.4 Estimated Delivery Performance 111 4.5 Results and Discussions 114 4.5.1 Fused silica fibre 114 4.5.2 Investigating the variation of launching angle 118 4.5.3 Investigating wavelength dependency: 355nm vs. 266nm 121 4.5.4 Investigating the use of DOE homogenisers 123 4.5.5 Sapphire Fibres vs. Fused Silica Fibres 128 4.6 Further Research 135 4.6.1 Hollow Waveguides and PCFs 135 4.6.2 Tapered Fibres 135 4.6.3 Hollow Tapered Pyrex-Glass 136 4.7 Conclusions 137 5 BONDING METHODS AND SPECTRAL ANALYSIS 138 5.1 Phosphor Bonding Methods 138 5.1.1 Introduction 138 5.1.2 Chemical Bonding 138 5.1.3 Vapour Deposition / Rf Sputtering 140 5.1.4 Flame and Plasma Spray 141 5.1.5 Discussion 142 - 3 - A. Khalid 5.2 Emission Spectral Analysis. 146 5.2.1 Introduction 146 5.2.2 Experimental Methodology 146 5.2.3 Excitation and emission spectra 148 5.2.4 Results and Discussions 149 6 INTENSITY MEASUREMENTS FOR PHOSPHORS 156 6.1 Absolute intensity measurements 156 6.1.1 Introduction 156 6.1.2 Methodology 157 6.1.3 Effect of distance, detector area and detection angle 161 6.1.4 Conversion to radiant flux and intensity 163 6.1.5 Results, discussions and measurement uncertainty 168 6.1.6 Further work 176 6.1.7 Conclusions 177 6.2 Quantum efficiencies and signal-to-blackbody-ratios 178 6.2.1 Introduction 178 6.2.2 Methodology 178 6.2.3 Results and Discussions 181 6.2.4 Conclusions 186 7 DETERMINATION OF PHOSPHOR LIFETIMES 188 7.1 Introduction 188 7.2 Methodology 188 7.3 Data Processing 191 7.4 Results, Discussions and Regression Analysis 195 7.4.1 YAG:Tm 195 7.4.2 Magnesium Manganese phosphors 200 7.4.3 YAG:Tb 205 7.4.4 Y2O3:Eu 215 7.4.5 YAG:Dy 218 7.5 Summary and Conclusions 220 8 DESIGN FOR ROTATING ENGINE COMPONENTS 223 8.1 Introduction 223 8.2 Component rotational speeds and linear velocities 223 8.3 Phosphor selection criteria 225 8.3.1 Single Phosphor Solution 225 8.3.2 Sample per revolution 229 8.3.3 Multiple Phosphor Solution 230 8.4 Probe System Design Discussion 231 8.4.1 Operating laser wavelength 231 8.4.2 Fibre optic 231 8.4.3 Single fibre probes on stationary targets 232 8.4.4 Dual fibre probes 234 8.4.5 Probe performance 235 8.5 Single fibre probe on rotating surfaces 237 8.5.1 Collection efficiency 237 - 4 - A. Khalid 8.6 Experimental Testing on Rotating Components 243 8.6.1 Experimental procedure 243 8.6.2 Hot rotating disc 245 8.6.3 Rotating at a constant temperature 248 8.7 Measurement Uncertainty 254 8.8 Conclusions 261 9 CONCLUSIONS, RECOMMENDATION AND FUTURE WORK 263 9.1 Summary 263 9.2 Recommendation 266 9.3 Future Work 266 REFERENCES 268 Word Count: 74,748 - 5 - A. Khalid List of Tables Table 1: Characteristics of different sensor types on the aeroengine. Summarised from [2] .................................................................................30 Table 2: Most common thermocouple types used in aeroengines...........................40 Table 3: Pros/Cons and performance of existing temperature measurement methods in gas turbines. .........................................................46 Table 4: Temperature range of various engine components..................................56 Table 5: Summary of typical process times from excitation to emission .................62 Table 6: Elements in the a) lanthanide series; b) transition metals series..............63 Table 7: Comparison of the ‘conventional two camera’ approach and the ‘filter wheel approach’ detection for the two-mode intensity method. ..................70 Table 8: Effect of increasing temperature on the probability of radiative (P r) and non-radiative (P nr ) decay. ................................................................72 Table 9: Comparison of different light detectors..................................................85 Table 10: Factors for consideration for coupling laser radiation into fibres ...............97 Table 11: Correction factors required for different wavelengths .......................... 112 Table 12: Maximum estimated transmittable energy at various wavelengths for different diameter fibres, based on 12ns pulses. ..................... 112 Table 13: Comparison of maximum transmissions, fluence and power densities for f=50mm and 25mm coupling lens. ............................................ 121 Table 14 : Transmission % of energy with and without the DOE ......................... 126 Table 15: Effective energy falling on the fibre face ........................................... 127 Table 16: Recommended minimum bend radius [147] ..................................... 131 Table 17: Summarised pros and cons of using sapphire fibres instead of fused silica/quartz fibres. .......................................................................... 132 Table 18: Comparison of various high temperature chemical binders [166] ........... 139 Table 19: Summary of the key issues related to different bonding techniques.............................................................................................. 142 Table 20: Summary of key characteristics of commercially available binders from ZYP Coatings......................................................................... 142 Table 21: Reference for common radiometric and photometric terminology ............................................................................................ 158 Table 22: Determined PMT P s.E c values ......................................................... 165 Table 23: Uncertainty budget for phosphor intensity......................................... 174 - 6 - A. Khalid Table 24: Comparison of the estimated limit of measurement based on theoretical/ideal conditions and experimental conditions. ................................ 184 Table 25: Temperature when the signal to blackbody radiation = 1. Simulation using an input laser energy of x1, x10, x100 mJ/pulse. ................... 186 Table 26: Uncertainty of furnace temperature ................................................. 189 Table 27: Excitation and emission wavelength investigations for different phosphors .............................................................................................. 190 Table 28: Charge balance of Mg:Mn phosphors cited in the literature................... 201 Table 29: Summary of the quenching temperature, maximum temperature that was determinable and the combined standard uncertainty. ............................................................................................ 222 Table 30: Summary of the useful temperature range determinable using the lifetime analysis for various phosphors ................................................... 222 Table 31: Summary of combined measurement uncertainties on stationary components.............................................................................. 222 Table 32: Summary of linear velocities, distance to target for various engine components at 13,000 RPM. ............................................................ 224 Table 33: Summary of the maximum acquisition time available for measurement.........................................................................................
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