Abstract: An improved plastic, injection-molded shroud/banded fan combination in which the shroud extends axially from an inlet portion to an outlet portion, and the outlet portion comprises means for connecting a heat exchanger to the shroud, More specifically, the shroud includes an inlet lip which is curved in cross-section and positioned at the inlet portion of the shroud. The lip extends radially inward and axially downstream from the inlet portion of the shroud to a trailing edge. An intermediate cylindrical wall is attached to said inlet lip. The intermediate cylindrical wall is positioned: 1) coaxially with the fan; and 2) radially between the inner surface of the shroud and portions of the outer surface of the fan band so as to form a wall-to-band radially restrictive running clearance.

Abstract: An axial flow fan includes blades mounted on a hub and extending radially outward to a shroud disposed around the hub. Pairs of stators are connected to the shroud at positions angularly spaced about the inner periphery of the shroud. Each pair of stators includes a trailing stator angularly spaced from a leading stator by a distance related to the number of blades of the cooling fan. A trailing stator of one pair is spaced from a leading stator of an adjacent pair by a distance different than the distance between leading and trailing stators of each pair.

Abstract: An improvement to forwardly skewed axial fans whereby blade camber and rake are coordinated with skew. The blades are characterized in that a line defined by the points of maximum chordwise camber (f.sub.max) as a function of changing radial position (r) is on the leading edge side of the mid-chord line (M.sub.CL) at values of r toward the root of the blade, and is less forwardly skewed than the leading edge (LE), the mid-chord line (M.sub.CL), and the trailing edge (TE) of said blade; the blade is raked forwardly so that the trailing edge of the blade tip is axially forward of the trailing edge at the blade root; rake (k) increases monotonically as radial position r increases from 0.75R to 1.0R, R being the fan radius; the blade has a relatively large pitch ratio (P/D); and rake is corrected to reflect the chordwise position of maximum camber.

Abstract: Centrifugal blowers which maintain a substantially constant (usually .+-.5%) static pressure field around the circumference of the blower's impeller, notwithstanding at least one abrupt radial or axial discontinuity in the volute of the blower, e.g., due to one or more external axial and/or radial constraints in an irregularly shaped package. The blower accommodates such constraints by including discontinuities in the volute; therefore the blower takes advantage of relatively unconstrained segments of the package to have an overall large size. Notwithstanding the volute discontinuities, a substantially constant pressure field around the impeller is achieved by maintaining a specific relationship between G(.THETA.) and H(.THETA.), G(.THETA.) being radial extent of the volute as a function of the angular displacement .THETA. around the impeller's circumference and H(.THETA.) being the axial extent of the volute as a function of .THETA., angular displacement around the volute.

Abstract: An airfoil having a suction surface and a pressure surface, the surfaces joined together at leading and trailing portions of the airfoil, the pressure surface converging toward the suction surface at a corner, the surface converging at the corner by an angle approximately equal to or greater than at least 30.degree., such that an air stream flowing from the leading edge and over the pressure surface separates from the pressure surface at the corner. The fan therefore has a thick nose section and is substantially thinner over the majority of its chord length. One or more guide ribs extend from the pressure surface to control the flow of boundary layer air.

Abstract: A blade for a fan or blower which has an abrupt transition region between an inner blade region which has a negative leading edge sweep angle, and an outer blade region which is highly forwardly swept. The outer blade region is further characterized by a blade chord that increases with increasing radius. The fan provides a low pitch width and superior noise and efficiency trade-offs.

Abstract: An axial flow fan comprising: a cental hub rotatable on an axis; and a plurality of blades extending from the hub, each of the blades comprising a root portion adjacent to the hub, and terminating in a tip portion, the root portions of the blades being approximately evenly spaced around the hub; wherein each of the blades exhibits a curvature from the root portion of the blade to the blade's tip portion, the curvature being in a plane that is perpendicular to the axis on which the fan rotates; and wherein the curvature differs between at least two of the blades, such that the distance between the tip portions of at least wo sets of adjacent blades is unequal. The invention therefore achieves the advantage of having uneven blade spacing near the tips while maintaining high solidity near the hub, where the blade spacing is even. Uneven blade spacing near the tips reduces noise. Having high solidity near the hub, where non-dimensional loading is highest, maintains higher dynamic performance.

Abstract: The invention features an axial fan for passing air through a heat exchanger, the fan comprising a hub rotatable on an axis and a plurality of blades, each of which extend radially outward from a root portion attached to the hub to a tip portion, the blades characterized by a trailing edge angle that varies by approximately 40.degree. or more over the radial extent of each blade. The blade trailing edge angle is preferably greater than 60.degree. at the root region.

Abstract: A rearwardly curved centrifugal blower having an annular envelope around the impeller, so that the rotating impeller draws air in through a central inlet and forces it radially outward into the envelope and out of an annular discharge. Multiple airfoil vanes are positioned in the annular envelope, in two axially displaced stages. The vanes are angled to turn and diffuse airflow entering the envelope.

Abstract: A centrifugal blower with rearwardly curved impeller blades positioned in a housing between two housing faces that are spaced apart along the impeller axis. One of the housing faces defines a housing inlet. The housing is substantially closed off with the exception of the inlet and an outlet. The blower is generally characterized in that the: (a) clearance between the impeller blades and at least one of the housing faces is greater than 30% of the impeller blade depth; (b) the impeller diameter is at least 70% of the housing dimension along that diameter; and (c) area of the blower outlet is greater than 70% of the area of a section of the housing taken perpendicular to the direction of airflow along the impeller axis.

Abstract: Boundary layer separation in a rearwardly skewed centrifugal impeller can be better controlled by designing the impeller blades with an "S" camber, i.e., with rearward curved radially extending blades in a centrifugal blower. The blades have a positive camber at a radially inward region and a negative camber at a radially outward region of the blade.