Abstract: An axial flow fan has a plurality of impeller blades spaced around a hub assembly. The leading edge of each blade overlaps completely the trailing edge of the preceding blade, and the angular spacing between the radial center lines of the blades is unequal, preferably varying in a sinusoidal pattern, so that tonal noise of the fan is effectively attenuated.

Abstract: Wind turbine of cross-flow type with curved or in sections straight vanes (1,2,9). Two vanes or sets of blades are formed in planes parallel to the rotor axis (3) and with the blade planes disposed approximately perpendicularly to one another.

Abstract: This invention is directed to an improved tandem marine propeller having sets of radially extending blades which are connected at their roots to a hub in tandem arrangement for minimizing drag adjacent the hub and having the blades configured by skewing one set forward and the other set backward and raking the blades of the two sets toward each other so that outer portions of the blades are equispaced radially about the hub and lie substantially in a common plane of rotation whereby loading on the blades of both sets is substantially equalized for increased efficiency.

Abstract: A wheel or rotor with a plurality of blades arranged at irregular or unequal pitch angles circumferentially of a disk, a hub or the like, wherein the characteristic level e.sub.k representative of the order-of-harmonic characteristic of blade pitch is defined bye.sub.k =10 log.sub.e d.sub.k +100where ##EQU1## Z=a number of blades k=1,2, . . . and n; n.gtoreq.Z.theta..sub.j =the angular position of the tip or root of each blade defined in terms of a central angle subtended at the center of a circle, which is the axis of said wheel or rotor, by an arc extended from a reference point on said circle to said tip or root of each blade on said circle, j=1,2, . . . and Z; andthe characteristic level e.sub.k satisfies the following conditions ##EQU2## where e=-13.14 log.sub.10 Z+99.70k=2,3, . . . n.

Abstract: A blender is provided which is comprised of an impeller having at least three sets of blades, a first set of blades positioned near the inlet of the blender and a second set of blades positioned near the outlet of the blender are radially extending and pitched, said first and second set of blades having a differential in the average pitch relative to each other. The third set of blades positioned between the inlet and outlet sets, which may be pitched or unpitched, include blades which are curved toward both the first and second set of blades. The blender has particular application to the smelter art and is useful for the continuous blending and agglomeration of fine particulate materials.

Abstract: A stirring device is disclosed for mixing liquid and dry ingredients in a tank. The stirring device employs an agitator prop having claws or fingers formed thereon to break up balls of dry ingredients, a shear plate to strain and shear ingredients forced therethrough by operation of the agitator prop and a pump prop. The agitator and pump props have reverse pitches with respect to each other such that both props push the ingredients toward the shear plate.

Abstract: In a fan with a fluid friction clutch wherein the housing of the clutch is connected with the fan or has fan blades attached thereto and wherein the surface of the clutch housing facing the air intake opening of the fan is provided with cooling ribs to carry off slippage heat, the improvement comprises flow direction means for reducing the effects of the secondary air flow around the clutch housing. The flow directing means comprise either the cooling ribs on the surface of the clutch housing facing the air intake opening of the fan which ribs are curved at the outer edges thereof in a direction reverse to that of the rotation of the fan; cooling ribs of construction angled in reverse direction to that of the direction of rotation of the fan; annular cooling ribs; or cooling ribs of conventional radial arrangement covered by a flow directing intake housing.