Theory and Design of Axial Flow Fan (Part I)

Abstract

In the axial fan, the flow pattern for the two dimensional flow in which the fluid flows in concentric cylindrical surface is free vortex. For free-vortex type axial-flow fan, we introduce an expression of circulation, lift and drag coefficient, blade efficiency for impeller and guide vane and show that the Howell's expression of lift is essentially identical with ours. Also we show the expression for manometric efficiency of blade element, whole impeller and guide vane and contra-rotating axial fan and overall manometric efficiency of complete fan including ducts. We can obtain at once the efficiency by these expression.