Prediction of onset of rotating stall using small perturbation theory for contra-rotating compressors

With its structural and aerodynamic advantages, the contra-rotating compressor (CRC) is considered an important approach to further improve the thrust-weight ratio of an aircraft engine. The configuration studied in this paper is a dual-stage contra-rotating compressor in laboratory, and the onset of rotating stall of the contra-rotating compressor in different rotating speed match schemes is studied with small perturbation theory and computational fluid dynamics (CFD) numerical method. The purpose of this study is to explore a fast and efficient method for prediction of the onset of rotating stall for contra-rotating compressor. Results show: (a) the small perturbation theory is a reliable and effective method for the prediction of the onset of rotating stall. At the condition of rotating speed ratio is less than or equal to 0.9, Rotor 2 is the first stall stage. Otherwise, Rotor 1 is the first stall stage; (b) the rotating speed match scheme has a significant impact on the location of the first rotating stall stage; (c) the errors of the small perturbation method arise mainly from the simplification of the flow models, and the strong disturbance between the two rotors of the contra-rotating compressor enlarges the errors.