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The Dynamics of Stall and Surge Behavior in Axial-Centrifugal Compressors

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The Dynamics of Stall and Surge Behavior in Axial-Centrifugal Compressors The Dynamics of Stall and Surge Behavior in Axial-Centrifugal Compressors by William T. Cousins Dissertation submitted to the Faculty of the Virginia Polytechnic Institute and State University in partial fulfillment of the requirements for the degree of DOCTOR OF PHILOSOPHY in Mechanical Engineering Walter F. O’Brien, Chairman Eugene F. Brown Milt W. Davis, Jr. Wing F. Ng Joseph A. Schetz December 2, 1997 Blacksburg, Virginia Key Words: Compressor, Stall, Surge, Unsteady-Flow, Dynamics, Axial, Centrifugal Copyright 1997, William T. Cousins The Dynamics of Stall and Surge Behavior in Axial-Centrifugal Compressors by William T. Cousins Committee Chairman: Walter F. O’Brien Department of Mechanical Engineering ABSTRACT The phenomena of stall and surge in axial-centrifugal compressors is in- vestigated through high-response measurements of both the pressure field and the flowfield throughout the surge cycle. A unique high-response forward-facing and aft-facing probe provides flow information. Several axial-centrifugal com- pressors are examined, both in compressor rigs and engines. Extensive dis- cussion is presented on the differences in axial and centrifugal rotors and their effect on the system response characteristics. The loading parameters of both are examined and data is presented that shows the increased tolerance of the centrifugal stage to instability. The dynamics of the compressor blade response are shown to be related to the transport time of a fluid particle moving through a blade passage. The data presented provides new insight into the dynamic in- teractions that occur prior to and during stall and surge. In addition, the incep- tion of rotating stall and the inception of surge are shown to be the same phe- nomena. An analytical dynamic model (DYNTECC) is applied to one of the compression systems and the results are compared to data. The results show that the model can capture the global effects of rotating stall and surge. The data presented, along with the analytical results, provide useful information for the design of active and passive stall control systems. ACKNOWLEDGEMENTS As is always the case, there have been many people who have had an influence on the work that is contained in this dissertation. I would like to espe- cially recognize my advisor, Dr. Walter O’Brien. It is certainly through his guid- ance and encouragement that this work is complete. In all the years of our rela- tionship, he has never been one to insist on things being done in a certain way, but has always been there to encourage and provide the guidance when re- quested. He works with students as colleagues, not as boss and worker. I cer- tainly owe him much for his support over the years and for helping to complete this work over a long distance. In addition, I would like to thank my committee, for their support and guidance in the completion of this work. Special thanks goes to Dr. Milt Davis at AEDC, for his guidance and support of the DYNTECC model. He has been interrupted many times with detailed modeling questions and has never failed to provide excellent support. I would also like to thank AlliedSignal Engines, for permission to publish this material. Special thanks goes to Mark Jones, Ed Palmreuter, Bill Water- man, and Craig Thompson, for their support in this effort over the years. It is through the vision and acceptance of my ideas that this work proceeded. Tests such as those presented here require significant support. The laboratory sup- port, especially from Paul Jobe and Manny Rubio has been superb, especially in light of my endless demands for data quality and the construction of special- ized instrumentation. Thanks also to all those others at AlliedSignal for their en- couragement and support of this work. I would especially like to thank my Mom and Dad, who probably won- dered if I would ever complete this work. It is through their many years of sup- port and encouragement that I have had the desire to learn, and the drive to complete this work. As always, there is a single person that stands out who has had a iii greater effect on this work than anyone else, and that is my wife Nina. She has given me total support and encouragement, taking care of family duties to pro- vide me with the environment and the time necessary to complete this effort. Above all that, the help in proofing this document into the late hours of the night can never be fully appreciated and recognized. And while they really don’t yet understand what this is all about, I would like to thank Katie and Jonathan, my children, for their tolerance to Dad’s frustrations and for their effort to keep the house quiet “so Dad could work.” I would like to dedicate this dissertation to my wife, Nina, whose love and consideration made this work possible. iv TABLE OF CONTENTS Acknowledgements......................................................................................... iii Table of Contents ............................................................................................v List of Figures ................................................................................................ vii List of Tables .................................................................................................xv Nomenclature................................................................................................ xvi 1.0 Introduction ............................................................................................ 1 2.0 Literature Review ................................................................................... 5 3.0 Theme and Focus of this Work............................................................. 8 4.0 Characteristics of Axial and Centrifugal Blades that Result in Differences in Dynamic Response............................... 9 4.1 The Pressure Rise Capability of Axial and Centrifugal Stages ... 9 4.2 Axial and Centrifugal Blade Response to Changing Inlet Conditions ........................................................................ 16 4.3 Axial and Centrifugal Stage Matching....................................... 19 5.0 Instrumentation Used for Dynamic Evaluation ................................. 21 5.1 Measurement of Flow Through a Complete Surge Cycle ......... 21 6.0 Compression Systems Examined ...................................................... 29 6.1 The Research Compressor....................................................... 30 6.2 The TFE1042 Compressor Rig ................................................. 31 6.3 The TFE1042 Engine................................................................ 32 6.4 The TFE731 Engine.................................................................. 33 7.0 Test Results and Dynamic Matching Analysis .................................. 36 7.1 Stall and Surge Inception in an Early Build of the TFE1042 Compressor Rig ............................................. 36 7.2 The Effects of the Centrifugal Impeller on Surge and Stall Dynamics - Research Compressor Results ............................. 44 v 7.3 Measurement of the Dynamics of a Complete Surge Cycle - TFE1042 Rig Results............................................................... 47 7.4 Fan and Compressor Interactions - TFE1042 Engine Results......................................................... 53 7.5 Interactions Within a Split Spool Compression System - TFE731 Engine Results........................................................... 56 7.6 Measurement and Test Data Accuracy..................................... 63 8.0 Evaluation of a Dynamic Model .......................................................... 64 8.1 The DYNTECC Compressor Modeling Technique.................... 64 8.2 The TFE1042 Geometry Input to the DYNTECC Model ........... 69 8.3 Results of the DYNTECC Model of the TFE1042 Compressor Rig ....................................................................... 70 8.4 The Missing Physics of the DYNTECC Model .......................... 83 9.0 Discussion of Results ......................................................................... 89 10.0 Conclusions ....................................................................................... 94 11.0 References.......................................................................................... 95 12.0 Vita ...................................................................................................... 99 vi LIST OF FIGURES Figure 1-1 T800 Engine Containing a 2-Stage Centrifugal Compression System ................................................................ 3 Figure 1-2 Typical Efficiency Characteristics for Several Compression Systems............................................................... 3 Figure 1-3 TFE1042 Engine w/o Afterburner Showing the 3-Stage Axial- Flow Fan and the 5-Stage Axial-Centrifugal Compressor ......... 4 Figure 4-1 Enthalpy-Entropy Diagram for a Centrifugal Compressor Stage..................................................................... 9 Figure 4-2 Enthalpy-Entropy Diagram for an Axial Compressor Stage..... 11 Figure 4-3 Typical Axial Rotor Loading Diagram ...................................... 13 Figure 4-4 Typical Blade-to-Blade Rotor Mach Number Distribution ........ 13 Figure 4-5 Typical Axial Stator Loading Diagram...................................... 14 Figure 4-6 Typical Blade-to-Blade Stator Mach Number Distribution ....... 14 Figure 4-7 Shape of the Stage Characteristics for a Compressor ............ 15 Figure 4-8 Loading Diagram for a Centrifugal Impeller............................
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