Clocking effect under different inlet guide vanes prewhirl angles in a centrifugal compressor

The stator clocking effect on the flow filed at three inlet guide vanes (IGV) prewhirl angles are experimentally investigated under design condition in a centrifugal compressor by X-type hot-wire/hot-film anemometry. The results show that stator clocking enables to changes the rotor discharge and the downstream stator inlet flow. The influence weakens when the distance from the rotor outlet increases. The magnitude of the clocking effect is different for different inlet guide vanes prewhirl angles. The flow range where the ensemble-averaged radial velocity changes at different stator clocking positions gets the widest under 0° prewhirl angle, next under -20°, then under 20°. The absolute flow angle changes evidently at different clocking positions. At different clocking positions, the maximum variations of unsteady absolute flow angles are respectively 1.6, 0.9 and 1.2 degree under 0°, 20° and -20° prewhirl angles. The variations of time-average absolute flow angle at different clocking positions are respectively 1.3, less than 0.5 and 0.84 degree under 0°, 20° and -20° prewhirl angles.