Experimental investigation of a counter-rotating compressor with boundary layer suction

This paper presents the aspirated modification of a dual-stage counter-rotating compressor which contains inlet guide vanes (IGVs), two counter-rotating rotors (R₁, R₂), and outlet guide vanes (OGVs). Uniform circular holes are circumferentially distributed over the rotors' tips on the shroud casing which are designed to remove the low-energy fluid near the shroud casing. OGVs are hollow blades with two slots designed on the suction side which can better control the flow on the suction surface through boundary layer suction. Related works about the experiments have been carried out since June 2012 and the effect of flow suction on the performance of the compressor is investigated in detail. Characteristic lines at a 70% corrected rotating speed are tested and those with higher rotating speeds will be studied in the near future. Experimental results indicate that boundary layer suction can improve the compressor characteristics and the best suction methodology varies along the operating line. At the near stall condition, suction from the R₂ tip region can obviously increase the efficiency and the total pressure ratio, as well as improve the flow capacity. Isentropic efficiency can be maximally increased by 4.24% with an increase of 1.94% in massflow under a suction flow of 160 m³/h. Suction at the R₁ position with a suction rate below 0.35% in a high flow situation can make the performance of the compressor better than others. Around the peak efficiency point, boundary layer suction from the slots of OGVs is the best choice in improving the efficiency, but it causes a 0.1% loss in the total pressure ratio.