Axial fans - ebm-papst A&NZ

Simon is giving a an overview of axial fans.

He gives a definition of axial fans by showing examples from the ebm-papst showroom. An axial fan is a fan that moves air along the axial direction of the product, along the shaft. Airflow direction can be towards the front or towards the back.

Axial fans are the traditional propeller fan and come in various designs. Simon demonstrates two 5-bladed high efficiency EC axial fans, but the number of blades can vary between two and 13. This affects the fan's noise characteristics.

The design of the blades shown is comparatively complex. The impeller is made of silica-reinforced plastic, but other materials such as aluminium, sheet steel, pressed sheet, GRP and other composites are available. Composite materials allow for a complex blade design, in particular the wing tip. Wing tips in axial fans are very similar to the tips of aeroplane blades. They stop air going from the positive side to the negative side on the edge of the blade and hence reduce turbulence. The wing tip can reduce noise by up to 3 dB(A).

Axial fans are typically used when high air volume with low static pressure is required. Typical static pressures lie between 20 and 180, and even up to 250 Pascals. The fans create a high volume of air with a high velocity. This means that the static efficiency of axial fans is quite low. This, as well as the issue of noise, can be addressed by using an AxiTop diffuser.
Simon shows a sample setup of an AxiTop mounted on an 800mm EC axial fan.
The AxiTop consists of two parts, an external and an internal diffuser. They reduce the amount of turbulence coming off the fan and increase the fan's efficiency. They also increase the static efficiency by reducing the velocity of the air coming off the fan.

In summary, axial fans create a high volume of air at a low pressure, and their static performance can be improved by using accessories such as the AxiTop diffuser.

Find out more about Axial fans on http://www.ebmpapst.com.au/en/.