To examine the influences of some typical design parameters(the inlet flow condition

blade number

and vane loading distribution) on the performances of the return vanes in a two-stage centrifugal compressor

a series of return vanes were designed and analyzed numerically by 3-D viscous code.It was found that the secondary flows in the return vane were usually very strong;however

improving the inlet flow uniformity

increasing the blade number and optimizing the vane loading distribution could weaken the secondary flows.Among these approaches

the effect of changing the vane loading distribution was most significant.Generally

the forward loading return vane could achieve higher total pressure recovery coefficient and much more uniform discharge flow than the backward loading return vane.