An experimental investigation of the vane clocking effects on the centrifugal compressor time-averaged performance

The clocking effect, known as a potential means to improve the aerodynamic performance of the turbomachinery, has been investigated widely in the multistage axial turbomachinery, but little reported on the radial turbomachinery. In the present paper, an experimental investigation was made on the vane clocking effect between the inlet guide vanes and the vaned diffuser in a medium-speed centrifugal compressor. The measured data show that the vane clocking has an effect on the aerodynamic performance of the researched centrifugal compressor stage. At the design point, the maximum efficiency variation is about 0.52 points and the maximum total pressure ratio variation is 0.004. When the inlet guide vane's stagger angle was adjusted to ?45°, the vane clocking effect is strengthened. The maximum efficiency and total pressure ratio variation for the design point, respectively, are 0.67 points and 0.006, and for the low flow rate point even, respectively, increases to 0.90 points and 0.007. The wake characteristics show that the maximum efficiency variation always arises at a similar clocking configuration, in which the upstream inlet guide vanes wake was detected to impinge on the diffuser blade leading edge. In addition, the profile pressure distribution on the diffuser blade was measured in detail and the blade loading analysis shows that there is no measureable variation for the vane clocking effect on the steady diffuser blade loading.