Computational Study of Rotating Stall in High-Speed Compressor

A computational study of compressor instability based on body force representation of each blade-row of a transonic stage has been implemented for both clean inlet flow and flow with circumferential total pressure inlet distortion. The computational results indicate that many aspects related to compressor instability differ from what was observed in the experiment: steady compressor characteristics, stalling mass flow as well as the key details in stall inception process. The discrepancy has been attributed to the inadequacy of the body force formulation, which only reproduces the design operating point of the research compressor. In order to overcome this inadequacy, a procedure is proposed and implemented to modify the compressor body force based on the experimental data to match the stalling mass flow and compressor characteristic slope near stall. To assess the adequacy of the modified body force formulation, instability calculations incorporating the modification are carried out for both clean inlet flow and flow with circumferential total pressure inlet distortion. The modified body force formulation gives a computed stalling mass flow in agreement with measured value. While it also yields the modal type stall inception that are in agreement with experiment for clean inlet flow, the computed stall inception with inlet distortion differs from experiments in which the stall inception is through spike followed by modal wave disturbance. The calculations with inlet distortion show that both the compressor performance and the stability margin deteriorate. Thesis Supervisors: Yifang Gong Research Engineer Choon S. Tan Senior Research Engineer Acknowledgements Many people have given me a lot of help in this thesis and made my life at MIT more enjoyable. I would like to express my deep gratitude to them. First and foremost, I would like to thank my advisors, Dr. Yifang Gong and Dr. Choon S. Tan for their guidance and support throughout this project. Much gratitude is also extended to Dr. James D. Paduano for his guidance, lots of help and financial support. I would also like to express my sincere thanks to those professors who taught me the courses at MIT: Professor Epstein, Professor Greitzer, Professor Spakovszky, Dr. Tan, Professor Drela in Department of Aeronautics and Astronautics; Professor Sonin and Professor Mckinley in Department of Mechanical Engineering. I believe all the knowledge I have learned at MIT will benefit my future development and even the whole life. In addition, I am also thankful to the staff and graduate students of Gas Turbine Laboratory. Paul Warren, Julie Finn, Holly Anderson, Dongwon Choi, Brenda Macleod, Beilene Hao, Andrew Luers, Neil Murray, Yong Wang, Yiben Lin, Lixian Liu, Deborah Pilczer, Sebastien Akouche, Jhongwoo Peck, Bobby Sirakov, Van-Man Lei, Chiang Juay Teo, Benny Chi Kin Yam, Dr. Hongwei Sun, Dr. Shengfang Liao. Their friendship and help has been invaluable and is well appreciated. I would like to thank my family, my parents and my sister for their continued moral support throughout all the time that I have spent at MIT. Last but not least, I would like to thank my girlfriend Lingling Li for her moral support and encouragement. This research was funded by the U.S Air Force under a Grant F49620-00-0014 and its support is gratefully acknowledged. Centents