Design and Experimental Investigation of a Mixed Flow Supersonic Compressor Stage

Abstract

Highly loaded transonic and supersonic compressors appear capable of meeting the future demands of small gas turbines and jet engines. Particularly mixed flow compressors, taking advantage of the increasing circumferential blade speed between rotor inlet and exit, represent a good compromise with regard to high pressure ratio and mass flow on the one hand, and favorable performance characteristics and efficiency on the other. However, operating a supersonic rotor as part of a stage involves a stator characterized by high turning angles, supersonic inlet conditions and a strong flow deceleration. In fact, the stator can be identified as the critical component regarding overall stage performance. Based on experimentally determined rotor exit flow conditions, the first part of this paper describes the design of a tandem stator with a strong shock in the stator entrance region, followed by subsonic flow turning and diffusion. The main thrust of this paper is to present the analytical results obtained in connection with the experimental investigation of the complete stage at design and off-design conditions. Rotor and stator flow as well as the overall stage performance are discussed in detail. The concept of the tandem stator proves to be suitable for managing the extremely high aerodynamic loading in the Stator. Experimental results reveal the design goals to be met in general.