Positive effects of installing guide wheels in rotary fans

»1 Ten-year cost breakdown for ventilating fans

»2 and »3 Geometry of flow through the air diffuser and outlet slot of rotary fans with and without guide wheels

»4 Airflow velocity as function of air diffuser nozzle width, with and without guide wheels

»5 Airflow velocity and exit angle as functions of air diffuser height

»6 Visualization of free jet from air diffusers with and without a guide wheel

»7 Effect of vane quantity on airflow velocity and exit angle of an air diffuser

»8 Case example 1 for volume flow and input current as functions of line frequency (rotary fan with 3 kW motor, fan Ø 710 mm, l = 4 650 mm)

»9 Case example 2 for volume flow and input current as functions of line frequency (rotary fan with 4.0 kW motor, fan Ø 900 mm, l = 4 000 mm)

»10 Drying with stock fans at a line frequency of 40 Hz, with guide wheel

»11 Drying of filler bricks at a line frequency of 40 Hz

»12 Savings on electricity and amortization for a chamber dryer with 50 rotary fans with motor ratings of 3.0 and 4.0 kW following an investment in guide wheels, new impellers and motors; net annual runtime 300 days, 24 h, cost of electricity 0.12 €/kWh

»13 Savings on electricity and amortization with allowance for improved flow profiles, as exemplified for 50 rotary fans with 2.2 and 4.0 kW motors, following an investment in guide wheels, new impellers and motors; net annual runtime 300 days, 24 h, cost of electricity 0.12 €/kWh

This article describes how the installation of guide wheels in rotary fans affects the flow of air into and out of the diffuser. In addition to altering the flow profiles and pressure losses, guide wheels help improve the drying capabilities of rotary fans. Potential savings on electricity are pointed out.

1 Introduction

Many off-the-shelf fans now come with guide wheels fitted as standard equipment. What is referred to as guide wheels actually consist of stationary vanes situated downstream of the fan’s impeller. They reduce the swirling motion in the flow of air to permanently improve the fan’s effective performance.

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