In the post “Industrial fans explained to non insiders / laymen” we introduced the distinction between axial and radial or centrifugal fans. In this post we will exclusively deal with radial fans, and in particular, with the blades included in the impeller.
You should keep in mind that in radial fans, the air (or the fluid) meets the impeller in axial direction and leaves it perpendicularly to the axis of the fan.
In this context, blades are fundamental. They are divided into three categories:
- Backward blades: in this type of impeller, the fluid is driven by the convex part of the blades (the back).
- Forward blades: in this type of impeller, the fluid is driven by the concave part of the blades (the front).
- Straight blades: impeller where the fluid is processed indistinctly with the back or front side
Concerning the performance, using negative blades involves a lower absorbed power and therefore a lower energy consumption: they typically offer an higher performance. In the same way, at equal range and size, the forward curved fan offers an higher performance concerning pressure, but also an higher absorbed power, and therefore an higher energy consumption.
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