US Patent 7896618 Centrifugal compressing apparatus

In a centrifugal compressing apparatus, a height of a blade of an impeller is made to decrease gradually from a front edge thereof to a rear edge thereof, and a rate of change of the height of the blade is relatively large near the rear edge. The height of the blade can be made large at the rear edge side under the design restriction that an exit width of the rear edge of the blade is set to a predetermined design value. The ratio of the width of the clearance and the height of the blade is thereby made relatively large. As a result, the ratio of a flow path area occupied by a clearance flow to a flow path area occupied by a main flow is reduced. Since the pressure loss is thus made small, a drop in the efficiency can be prevented.