Patent ID: 8348593
Filing Date: 2013-01-08
Classification: F04D

Abstract:
1. A serial axial fan comprising: a first axial fan; and a second axial fan connected to the first axial fan along a central axis of the first axial fan; wherein the first axial fan includes: the second axial fan includes: in the first impeller, an angle defined by a rotational plane, perpendicular or substantially perpendicular to the central axis, of the first impeller with a chord of each first blade on an imaginary cylindrical surface centered about the central axis increases as a radius of the imaginary cylindrical surface increases; a first solidity, which is defined as a ratio of a chord length of the first blades of the first impeller to a pitch of the first blades, is greater than a second solidity, which is defined as a ratio of a chord length of the second blades of the second impeller to a pitch of the second blades, when the first solidity and the second solidity correspond to an additional imaginary cylindrical surface taken at an outer radial position of each of the first blades and the second blades; and the first solidity is greater than the second solidity along most of the radius of the imaginary cylindrical surface.