The centrifugal compressor has several groups of blades installed and each blade group includes several blades in impeller circumference and concentrical with the rotating center of the impeller rotating axle. The single blades of blade group near the impeller can rotate. It case that the air inlet vaolume is changed, the diffuser efficiency will reduce and the air flow can not flow easily from one blade to the other. Therefore, the blades will rotate to change their front wing central line angle to conform the direction of the air flow the impeller exhausts. So, even if the inlet air volume is changed, the efficiency of the diffuser may be maintained at relatively higher level. |