Experimental Investigations of a Recently Developed Supersonic Compressor Stage (Rotor and Stage Performance)

The experimental investigations of a recently developed supersonic compressor stage working with a strong shock wave both in the rotor and stator are described. The shock in the inlet area of the rotor is stabilized by the geometry of the rotor blade channel, whereas the position of shocks in the stator is controlled by the back pressure. Due to this, the static pressure rise is distributed to the rotor and stator avoiding a higher loading of the stator. In the first part the performance of the rotor alone has been investigated. The conducted probe and static wall pressure measurements allowed a detailed analysis of the flow through the rotor. The determined performance characteristics of the rotor show the peculiarities of the rotor at different speeds and throttle positions. In addition to the static wall pressure measurements the nonsteady pressure distributions have been measured at the casing wall by piezoelectric pressure transducers. Since this rotor (type ②) has been designed with the same relative inlet Mach number and turning as the previously investigated supersonic rotor (type ①), a direct comparison of these rotors can be made. In the second part of these investigations the rotor of type ② has been combined with a tandem cascade as a stator, to investigate the supersonic compressor stage. With heavy throttling a static pressure ratio of 3,5 (p₃/p₁) has been achieved. The evaluation of the probe measurements allowed a better estimation of the overall performance of this supersonic compressor stage.