Investigation of the off-Design Performance of an Axial-Flow Blower

Abstract

When blade pitch-chord ratio becomes small, the fluid outlet angle of the moving and guide vanes may be constant throughout all the flow ranges. This paper calculates the off-design performance of an axial-flow blower assuming the outlet angle be constant. Result is that the stage characteristics can be easily assumed by the whirl coefficient of mean geometrical radius of design flow and that the change of blade tip turning angle is greater than the root. This shows a reason why surging is caused by the reverse flow of a blade tip radius.