Forward swept centrifugal fan wheel

1. A forward swept centrifugal fan wheel comprising:

a first endring ( 10 );

a second endring ( 11 );

a plurality of blades ( 12 ) connected between the first endring and the second endring, each blade having a substantially continuous arcuate form that extends from the first endring to the second endring along an axis parallel to an axis of rotation (A-A); and

each blade having a substantially continuous arcuate cross-section taken with respect to a plane which extends normally from the axis of rotation (A-A); and

each blade when viewed in plan with a tangent line (T) is disposed in the plan, having a point (P) midway between the first endring and the second endring such that the point (P) leads each blade in the direction of rotation (D) of the wheel in a convex blade orientation.

2. The forward swept centrifugal fan wheel as in claim 1 , wherein the arcuate form comprises a circular section comprising a radius (R) and taken with respect to a tangent line (T).

3. The forward swept centrifugal fan wheel as in claim 1 , wherein a convex portion ( 17 ) of the blade projects in the direction of rotation (D) of the fan wheel.

4. The forward swept centrifugal fan wheel as in claim 1 , wherein each blade comprises a leading edge ( 15 ) and a trailing edge ( 16 ), the trailing edge disposed behind the leading edge with respect to a direction of rotation.

5. The forward swept centrifugal fan wheel as in claim 1 , wherein the arcuate form comprises a parabolic section.