Intra-Stator Transport of Rotor Wakes and Its Effect on Compressor Performance

The stagnation temperature profiles which have been observed recently downstream of the stators in high Mach number compressor stages are shown to be due to transport of the rotor wakes across the main streamlines during their passage through the stator. The rotor wake fluid has energy in excess of the inviscid flow, and it is collected by the pressure side of the stator. A wake transport theory is presented, which connects the temperature profile to the rotor blade loss factor, and so provides a new method for determination of the losses in a rotor under actual operating conditions. The theory compares favorably with a special helium-tracer experiment designed to check it, as well as with temperature measurements in two high Mach number stages.