Application of casing treatment to an industrial axial-flow fan

Abstract

This paper deals with an experimental investigation into the influence of a vaned recess casing treatment on the performance of an industrial-type axial-flow fan with a hub-tip ratio of 0.4. The treatment has been tested in a variety of configurations relative to the fan, with an emphasis on the amount of fan blade tip exposure to the treatment. Two sets of blading, one of which is of the fully reversible type, have been investigated.Detailed flow measurements have been carried out with a slanted hot wire probe to provide an insight into the operation of the device and into the nature of the rotating stall in the solid casing configuration. Strain gauges have been employed to enable blade stresses to be recorded and an in-duct microphone to enable comparative tests on fan noise has also been used. NOTATION P R fan input power (kW) v r radial velocity (m/s) v t tangential velocity (m/s) (positive in the direction of rotor rotation) DH stage enthalpy rise ¼ P R =ṁ, where m is the mass flowwhere q v is the volume flowrate (m 3 /s) and DP the pressure rise across the fan (Pa)where v a is the axial velocity (m/s) and u m the mid-span blade speed (m/s) Φ solid flow coefficient at the stall point for solid casing Φ treated flow coefficient at the stall point for treated casing Ψ total-to-static pressure rise coefficient ¼ DP=ð0:5ru 2 m ) Ψ solid peak pressure rise coefficient for solid casing Ψ treated peak pressure rise coefficient for treated casing INTRODUCTION

A Computational Study on the Performance Improvement of Low-Speed Axial Flow Fans with Microplates

“…Yamaguchi et al (2010) designed radial-vaned air separators for an axial flow fan in their experiment and studied their stall suppression effects. Recess vaned casing treatment was applied by Azimian et al (1990) and Hill et al (1998) to axial flow fans to improve the stall margin and pressure rise. Bladetip modifications were adopted by Corsini et al (2009Corsini et al ( , 2010 to control the leakage vortex and reduce noise in axial flow fans.…”

Performance Improvement on Axial-Flow Fan by Imposing Proper Frame Ribs

“…Hill et al [4] conducted an experimental investigation on the influence of a grooved-case treatment on the performance of an industrial-type, axial-flow fan with a hub-tip ratio of 0.4. The treatment has been tested in a variety of configurations relative to the fan, with an emphasis on the amount of fan blade tip exposure to the treatment.…”

Effect of Partial Shrouds on the Performance and Flow Field of a Low-Aspect-Ratio Axial-Flow Fan Rotor

“…These techniques generally involve some form of casing treatment near the rotor tip for the purpose of delaying rotor tip stall or reducing the detrimental effects resulting from excessive tip clearance. These techniques are casing treatment [6], vortex generators on the casing wall and rotor blades [7], recessing the casing over the rotor tips [8], recessed vane casing [9], and shrouding of the blades. In addition many active techniques are used to control tip clearance flows.…”