Design and Rotor Performance of a 5:1 Mixed-Flow Supersonic Compressor

In consideration of further jet-engine developments required by applications for supersonic travel aircraft, airbreathing propulsion of space vehicles, or only the improvement of conventional high-performance turbo-engines, highly loaded supersonic compressors seem to meet the future demands. Particularly mixed-flow compressor stages with moderate supersonic rotor and stator inlet flow reveal the potential of high pressure rise and mass flow as well as favorable performance characteristics and efficiency. The first part of this paper presents analytical considerations for mixed-flow supersonic compressors with strong shock waves. This theoretical approach proves to be essential besides established design tools in order to ensure safe rotor and stage operation in accordance with the design objectives. In this context, the conditions for shock wave stabilization within a diagonal rotor passage are discussed in detail for design and off-design rotational speeds. The main part of this paper, however, presents the results and flow analysis obtained by extensive experimental investigations of the designed mixed-flow compressor rotor. The investigations were restricted to operation without stator in order to strictly separate rotor performance from rotor-stator interactions. The results reveal the design goals to be met in general. Mass flow, total pressure rise, and efficiency in particular show a good agreement with the design properties for near-surge operation at design and off-design conditions.