Experimental study of sweepand dihedral effects on compressor cascade performance

In this paper a straight blade(STR), a forward-swept blade(SWF), and a blade combining forward sweep and positive dihedral(SCB) have been investigated in a linear compressor cascade at design and off-design incidence. The result shows that compared to STR, lower blade loading, lower diffusion factor and shorter axial static pressure diffusion are obtained near the endwall of SWF and SCB, which means lower loss near the endwalls of SWF and SCB despite the fact that SWF and SCB have higher loss at midspan. The accumulation of low-energy fluid, and thus flow separation occurring in the endwall/suction surface corner are avoided by pitchwise and spanwise surface static pressure gradient in SWF and SCB. The three-dimensional effect of SCB on the endwall boundary layer is stronger than that of STR and SWF. Further work should be done to seek the optimal matching between sweep and dihedral to take full advantage of the positive effect of sweep and dihedral on the endwall flow.