Boundary layer controlled logarithmic spiral blade

摘要

An impeller structure for a centrifugal fan apparatus includes a circular back plate, a ring-shaped shroud, and a tubular hub. The ring-shaped shroud and the tubular hub are respectively located a predetermined distance above and at the center of said circular back plate. The impeller structure further includes a plurality of blades which are annularly disposed around the tubular hub between the circular back plate and the ring-shaped shroud. Each of the plurality of blades includes a chord with a logarithmic spiral shape, and a mean camber line with an angle of return against the chord.

主权项

1. An impeller structure for a centrifugal fan apparatus, the impeller structure comprising:
a circular back plate; a ring-shaped shroud located a predetermined distance above the circular back plate; a tubular hub located at a center of the circular back plate; and a plurality of blades annularly disposed around the tubular hub between the circular back plate and the ring-shaped shroud, a chord line of each of the plurality of blades following a logarithmic spiral wave, a mean camber line of each of the plurality of blades provided with an angle of return against the logarithmic spiral function of the chord line, and a surface curvature of each of the plurality of blades distinct from the logarithmic spiral wave; wherein a thickness of each of the plurality of blades increases along the mean camber line from a leading edge to a position of maximum thickness located at a distance of about ⅕ to ⅓ away from said leading edge and then decreases from said position of maximum thickness to a trailing edge.