Experimental Investigation of the Performance of a Supersonic Compressor Cascade

Results are presented from an experimental investigation of a linear, supersonic compressor cascade tested in the supersonic cascade wind tunnel facility at the DFVLR in Cologne, Federal Republic of Germany. The cascade was derived from the near-tip section of a high-throughflow axial flow compressor rotor and has a design relative inlet Mach number of 1.61. Test data were obtained over the range of inlet Mach numbers from 1.30 to 1.17. Side-wall boundary layer suction was used to reduce secondary flow effects within the blade passages and to control the axial-velocity-density ratio (AVDR). Flow velocity measurements showing the wave pattern in the entrance region were obtained with a laser anemometer. The unique-incidence relationship for this cascade, relating the supersonic inlet Mach number to the inlet flow direction, is discussed. The influence of static pressure ratio and AVDR on the blade performance is described, and an empirical correlation is used to show the influence of these (independent) parameters for fixed inlet conditions on the exit flow direction and the total-pressure losses.