抄録
Numerical study was carried out on a transonic compressor
rotor, NASA Rotor 37, with different configurations of
circumferentially contoured endwalls to understand the
fundamental flow mechanisms of casing treatment effect. The
result showed the wall contouring above the blade leading edge
had significant stall margin improvement and insignificant
efficiency and pressure ratio drops. By applying the second
invariant Q, two major vortex structures were observed near the
stall conditions. One was tip leakage vortex and the other was
rotating instability vortex. The rotating instability vortex seemed
to be induced by the interaction between the inflow and reverse
flow near the endwall. In the case with wall contouring, enlarged
clearance gap encouraged the tip clearance flow and relieved the
interaction that caused the rotating instability vortex. Alleviation
of the vortex led to the improvement of stall margin as a
consequence.
