BLADE OF AXIAL FLOW FAN Russian patent published in 2014 - IPC F04D29/38 

FIELD: ventilation.

SUBSTANCE: blade of axial flow fan is designed for household use, as well as in supporting mechanisms to ensure air circulation. The blade comprises a convex leading edge, a concave trailing edge, a root part and an upper edge. The radius of curvature of the concave trailing edge is made equal to the radius of curvature of the blade midline, and the radius of curvature of the convex leading edge is selected on the basis of providing the necessary thickness of the blade on average on its section length. The entrance angle of the air mass in the intervane channel and the angle of outlet from it are related as follows: γ=tan-1(φ/cosα), where γ is the angle of outlet of the air mass from the intervane channel; φ is coefficient taking into account the loss of speed of the air mass in the intervane channel, comprising from 1 to 0.9; α is the entrance angle of the air mass in the intervane channel. Parameters of the blade are made according to the following expressions: R=a/(cosα-cosγ), where R is radius of curvature of the blade midline; a is the width of the blade in the axial direction, l=(2πR(γ-α))/360, where l is total length of the blade, b=R(sinγ-sinα), where b is the width of the blade in front.

EFFECT: increased performance, the pressure and the coefficient of efficiency of the fan while maintaining the necessary strength and stiffness of the blade during operation.

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