Centrifugal Compressors: A Strategy for Aerodynamic Design and Analysis PDF
Preview Centrifugal Compressors: A Strategy for Aerodynamic Design and Analysis
A STRATEGY FOR AERODYNAMIC DESIGN AND ANALYSIS Ronaid Ha Aungler NEW YORK ASME 9RESS 200.0 � 2000 by The American Society of Mechanical Engineers Three Park Avenue, New York, NY 10016 All rights reserved. Printed in the United States of America. Except as permitted under the United States Copyright Act of 1976. no part of this publication may be reproduced or distributed in any form or by any means. or stored in a database or retrieval system, without the prior written permission of the publisher. Information contained in this work has been obtained by the American Society of Mechanical Engineers from sources believed to be reliable. However. neither ASME nor its authors or editors guarantee the accuracy or completeness of any information published in this work. Neither ASME nor its authors and editors shall be responsible for any errors, omissions, or damages arising out of the use of this information. The work is published with the understanding that ASME and its authors and editors are supplying information but are not attempting to render engineering or other professional services. If such engineering or profes- sional services are required, the assistance of an appropriate professional should be sought. ASME shall not be responsible for statements or opinions advanced in papers or pit-riled in ils publications (B713). Statement from the Bylaws. . . . Authorization to photocopy material for internal or personal use under circum- stances not falling within the fair use provisions of the Copyright Act is granted byASME to libraries and other users registered with Copyright Clearance Center (CCC) Transactional Reporting Service provided the base fee of $4.00 per page is paid directly to the CCC, 222 Rosewood Drive, Danvers, MA 01923. Library of Congress Cataloging-in-Publicarion Data Aungier, Ronald H. Centrifugal compressors : a strategy for aerodynamic design and analysis / Ronald 1-1.Aungier p. cm. ISBN 0-7918-0093-8 1. Compressors—Aerodynamics. 2. Compressors—Design and constmction. 1. Title. TJ267. S. CSA96 2000 621.5' l——dc21 99-39156 CIP To Anne, with love and gratitude. Beth and Joan, from a proud father. Dad and Mom, whose sacri�ces made it possible. TALE CON’E'EN’Eg PREFACE xi ‘H. ENTROIUCTHON 1 1.1 The Centrifugal Compressor Stage 2 ......................... 1.2 Dimensionless Parameters 5 .................................. 1.3 Performance Characteristics 9 ................................ 1.4 Similitude 10 ................................................... 1.5 Units and Conventions 11 ..................................... 2. THERMODYNAMBCS 13 2.1 Fundamental Laws of Thermodynamics 14 .................. 2.2 Head and Efficiency 16 ........................................ 2.3 The Gas Equation of State 19 ................................. 2.4 Thermally Perfect Gases: The Caloric Equation of State 20 ..................................................... 2.5 The Thermal Equation of State for Real Gases 21 .......... 2.6 Thermodynamic Properties of Real Gases 24 ................ 2.7 Thermally and Calorically Perfect Gases 25 .................. 2.8 Perfect Gas Models Applied to Real Gases 26 ............... 2.9 Component Performance and Losses 27 ..................... vi 0 TABLE OF CONTENTS 2.10 Approximate Liquid and Two—Phase Flow Models 30 ....... 2.11 Equilibrium Flash or Liquid Knockout Calculations 31 ...... 3. FLUID MECHANECS 35 3.1 Flow in a Rotating Coordinate System ................... 37 3.2 Governing Equations for Adiabatic lnviscid Compressible Flow 39 ......................................... 3.3 Adiabatic lnviscid Compressible Flow Analysis 42 .......... 3.4 Boundary Layer Analysis 43 .................................. 3.5 Vector Operators 48 ........................................... 4. THE IMPELLER WORK INPUT 51 4.1 The Slip Factor 54 .............................................. 4.2 The Impeller Distortion Factor 57 ............................ 4.3 Clearance Gap Flows 58 ....................................... 4.4 Windage and Disk Friction Work 60 .......................... 4.5 Leakage Work 62 .............................................. 4.6 Recirculation Work 66 ......................................... 5. ONE-DIMENSIONAL AERODYNAMIC PERFORMANCE ANALYSIS 69 5.1 One—Dimensional Flow Analysis 73 ........................... 5.2 Inlet Guide Vane Performance 76 ............................ 5.3 Impeller Performance 79 ...................................... 5.4 Vaneless Annular Passage Performance 85 .................. 5.5 Vaned Diffuser Performance 88 .............................. 5.6 Return Channel Performance 95 .............................. TABLE OF CONTENTS 0 vii 5.7 Volute and Collector Performance 99 ........................ 5.8 Overall Stage Predictions 101 ................................. 5.9 Multistage Compressor Analysis 104 ......................... 6. PRELIMENARY AERODYNAMEC DESEGN AND COMPONENT SIZING 109 6.1 The Preliminary Design Strategy 111 ......... . ............... 6.2 Simple Performance Correlations 114 ....... ’3.......,......... 6.3 Component Matching 115 .................................... 6.4 A Computerized Preliminary Design System 117 ............ 6.5 Impeller Sizing 118 ............................................ 6.6 Vaneless Diffuser Sizing 121 .................................. 6.7 Vaned Diffuser Sizing 122 ............................ _........ 6.8 Return System Sizing 123 ..................................... 6.9 Volute Sizing 125 .............................................. 6.10 Implementation of the Design System 125 .................. 7. GENERAL GAS PATH AND EMPELLER DESIGN 129 . 7.1 The General Gas Path Design Strategy 130 .................. 7.2 Useful Curve Forms for Gas Path Design 133 ................ 7.3 End-Wall and Quasi-Normal Construction 141 .............. 7.4 Blade Mean Line Construction 143 ........................... 7.5 Blade Surface Construction 145 .............................. 7.6 Blade Passage Throat Area 147 ............................... 7.7 The Blade Leading Edge 148 .................................. 7.8 A Computerized Gas Path Design System 149 .............. 7.9 Impeller Detailed Design 151 ................................. viii 0 TABLE OF CONTENTS 8. VANELESS JEFFUSER DESIGN 159 8.1 Geometric Construction 160 .................................. 8.2 The Design Procedure 161 .................................... 8.3 Rotating Stall Considerations 165 ............................ 9. VANED DIFFUSER DESIGN 167 9.1 Vaned Diffuser Performance Parameters 170 ................ 9.2 Design Criteria 171 ............................................ 9.3 Vaned Diffuser Stall 174 ...................................... 9.4 Vaned Diffuser Inlet Design 177 .............................. 9.5 Vaned Diffuser Sizing 178 .................................... 9.6 Vane Design 180 ............................................... 9.7 Analysis of the Design 182 .................................... 9.8 A Computerized Design System 184 ......................... 10. RETURN SYSTEM DESIGN 187 10.1 Return System Gas Path Construction 188 ................... 10.2 Return Channel Vane Construction 191 ...................... 10.3 A Computerized Interactive Design System 192 ............ 10.4 Return System Design Recommendations 193 .............. 11. VOLUTE DESIGN 195 11.1 Geometrical Construction 196 ................................ 11.2 Fundamental Design Concepts 199 ........................... 11.3 Aerodynamic Design Considerations 200 .................... TABLE OF CONTENTS 0 ix 12. QUASi-THREE-DIMENSEONAL FLOW ANALYSIS 205 12.1 Fluid Dynamics Models 207 ................................... 12.2 Gas Path Geometry 209 ....................................... 12.3 The Hub-to-Shroud Flow Governing Equations 211 ........ 12.4 Conservation of Mass and Momentum 211 ................. 12.5 Repositioning Stream Surfaces 214 ........................... 12.6 The First Iteration 215 ......................................... 12.7 ChokedFlow.................-............a: 216 ............... 12.8 The Blade-to-Blade Flow Governing Equations 216 ......... 12.9 Linearized Blade-to-Blade Flow 220 .......................... 12.10 Numerical Solution for the Stream Function 222 ............ 12.11 Iteration for Gas Density 225 ................................. 12.12 Quasi-Three-Dimensional Flow 226 ........................... 13.. POTENTIAL FLOW ANALYSIS IN THE BLADE-TO-BLADE PLANE 231 13.1 Definition of the Problem 233 ................................ 13.2 The Stream Function Solution 237 ............................ 13.3 The 'GasDensity Solution 244 ................................ 13.4 Some Useful Features 247 ..................................... 13.5 Typical Results 249 ............................................. 14. TIME-MARCHING ANALYSIS OF THE BLADE-TO-BLADE PLANE FLOW 251 14.1 Definition of the Problem 254 ................................ 14.2 Boundary Conditions 257 ..................................... 14.3 Fundamental Concepts in Numerical Stability 261 .......... x 0 TABLE OF CONTENTS 14.4 Numerical Stability for the Blade-to-Blade Flow Application 264 ................................................ 14.5 The Solution Procedure 267 ................................... 14.6 Typical Results 268 ............................................. 15. BOUNDARY LAYER ANALYSIS 271 15.1 Two—Dimensional Laminar Boundary Layer Analysis 273 .................................................... 15.2 Two-Dimensional Turbulent Boundary Layer Analysis 276 .................................................... 15.3 Blade Passage Profile Losses 279 ........ . .................... 15.4 End-Wall Turbulent Boundary Layer Analysis 279 ........... ANSWERS TO EXERCISES 293 REFERENCES 301 ABOUT THE AUTHOR 309 INDEX 311
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