The paper presents comparative studies on low-speed isolated rotors of free vortex
design and controlled vortex design (CVD), in order to survey the impact of the vortex
design method on the stall behavior of axial flow turbomachinery. The studies are
based on 3D laser Doppler anemometer studies and global performance measurements,
supplemented with literature data. CVD bladings are characterized by radially outward
flow on the suction side due to spanwise changing circulation, and increased near-tip
solidity and/or loading. These features were found to increase the near-tip endwall
flow blockage and loss at the design flow rate, and to hasten stall. On this basis,
it has been concluded that CVD tends to be disadvantageous from the viewpoint of the
stall behavior. It was confirmed that forward blade sweep is a remedial strategy for
moderating the stall-hastening effects of CVD, while retaining the favorable features
of CVD.
