Application of Visual Results for Design of Mixed Flow Fan which has an Axial Flow Fan Structure

Abstract

Low pressure axial flow fans without stator blades or guide vanes are generally used in order to achieve light weight, low cost and a simple structure, and to conserve space when mounted for automobile cooling system. However, since flow resistances in front and back of the fan are very strong, air tends to flow diagonally at the fan outlet side. The fan does not operate as an axial flow fan. In this report, we describe work conducted on a motor fan, mainly from the standpoint that analysis and improved understanding of actual air flow conditions lead to improved design. As for the measurement of air flow at the outlet and inlet side of the fan, the five hole-pitot tubes were used. And the reverse flow area was visualized to adhere tracer particles which are in the air flow to the pressure surface of the blades. As a result, we could predict the air flow among fan blades and portion and shape of the reverse flow area. These data were useful for designing the mixed flow fan which has the structure of an axial flow fan.