The hub ratio
The hub is usually compared to an axial fan.
The ratio of the hub diameter to the impeller diameter is the ratio of the hub, and the axial fan has the low pressure, medium pressure and high pressure form. Under the given flow rate, the larger the hub ratio, the greater the output pressure.
The hub ratio is greater than 0.4 for the low pressure (low wheel ratio) type axial fan; the hub ratio is greater than 0.71 for the high pressure (high wheel ratio) type axial fan; the hub ratio is between 0.4 and 0.71 for the medium pressure (the hub ratio ) Type axial flow fan.