Abstract: A turbomolecular pump capable of maintaining a maximum discharge rate even in a higher pressure has rotor blades or stator blades formed such that surface angles on a first surface of the blades facing the direction of rotation differ between an inlet port side of the blades and an outlet port side. The surface closer to the inlet port has a larger angle than on a side closer to the outlet port. One side of the blades has a plurality of surface portions each with different angles. The angles of the surfaces are in the range of 20° to 50° on the inlet port side, 10° to 40° on an intermediate portion, and 10° to 90° on the outlet port side. The angles of the first and second surface portions are larger than that of the intermediate surface portion.

Abstract: The invention concerns a blade profile for aircraft rotor, comprising, between a leading edge (1A) and a trailing edge (1B), a suction face (2) and a blade face (3) whereof the geometric locus of the equidistant points of the latter defines the curvature. The invention is characterised in that the value of the ratio of the maximum curvature to the maximum thickness develops linearly with the profile (1) relative thickness and ranges between 0.13 and 0.19 for a relative thickness of 7% of the chord (C) and ranges between 0.18 and 0.24 for a relative thickness of 15% of the chord (C).

Abstract: A rotator member, for example an airfoil of a rotating blade, is provided with additional stiffness in a radially outer portion of the member by including in the outer portion at least one corrugation extending generally along the width, for example chordwise, of the member.

Abstract: A compressor casing includes an axially convex inner surface for surrounding a row of rotor blades with radial gaps therebetween. The tip of the blades complement the casing contour for reducing blade tip losses and flow blockage.

Abstract: A compressor airfoil includes pressure and suction sides extending from root to tip and between leading and trailing edges. Transverse sections have respective chords and camber lines. Centers of gravity of the sections are aligned along a double bowed stacking axis for improving performance.

Abstract: An airfoil includes a leading edge chord barrel between a root and a tip, and forward aerodynamic sweep at the tip.

Abstract: An axial flow fan for an air conditioner is disclosed. This axial flow fan is capable of changing the shape of blades by varying a design factor such as a chord length, a sweep angle, etc., generating an enough flowing amount of a fan for implementing an efficient heat radiation of a heat exchanger, and decreasing a noise which occurs during an air flowing operation of the fan, so that it is possible to implement a high efficiency and low noise fan system. The above-described axial flow fan according to the present invention includes a hub engaged to a rotary shaft of a motor, and a plurality of blades engaged to the hub, wherein assuming a coordinate which is obtained by computing a distance R in a radial direction of the blade into a distance from a radius Rh to a radius Rt at a blade tip BT based on a non-dimensional method as “r” (r=(R−Rh)/(Rt−Rh), a maximum camber ratio Hc(r) which is a ratio between a maximum camber Cmax and a chord length 1 has 0.02±0.

Abstract: Upper and lower faces of a helicopter blade aerofoil are defined by the following coordinates. TABLE 1 X/C Yup/C Ylow/C 0.00000 0.00000  0.00000 0.00100 0.00511 −0.00584 0.00250 0.00843 −0.00813 0.00500 0.01218 −0.01014 0.00750 0.01505 −0.01136 0.01000 0.01747 −0.01218 0.01250 0.01959 −0.01277 0.01500 0.02150 −0.01328 0.01750 0.02325 −0.01375 0.02000 0.02487 −0.01415 0.02500 0.02780 −0.01483 0.05000 0.03891 −0.01714 0.07500 0.04682 −0.01862 0.10000 0.05291 −0.01979 0.15000 0.06152 −0.02206 0.20000 0.06666 −0.02470 0.25000 0.06892 −0.02729 0.30000 0.06895 −0.02949 0.35000 0.06841 −0.03109 0.40000 0.06744 −0.03211 0.45000 0.06568 −0.03270 0.50000 0.06301 −0.03272 0.55000 0.

Abstract: An impeller for use in a centrifugal blower comprises a hub for receiving a driving torque at a central portion thereof, a shroud of a ring-like shape in plane formed with an opening for air intake at the center thereof and opposed to the hub across a required distance therebetween, and a plurality of vane members interposed between the hub and shroud as circumferentially spaced from one another at required intervals, the impeller having an arrangement wherein an leading edge of each vane member has varied angles (inlet angles) with respect to a tangent line thereat thereby conforming to inflow angles of an air flow guided by the vane member at different points of a span between the shroud and hub.

Abstract: A novel concept for a propeller blade configuration incorporates the model of the natural wave behavior. The leading edge of the propeller blade is parallel to the trailing edge, but offset by a given amplitude. The surfaces between the leading and trailing edges are rounded so as to promote proper fluid sheet formation along the surface and to reduce undesirable vortice formation. Best results are obtained by modeling the surfaces along a sine or tangent function.

Abstract: A novel concept for a propeller blade configuration incorporates the model of the natural wave behavior. The leading edge of the propeller blade is parallel to the trailing edge, but offset by a given amplitude. The surfaces between the leading and trailing edges are rounded so as to promote proper fluid sheet formation along the surface and to reduce undesirable vortice formation. Best results are obtained by modeling the surfaces along a sine or tangent function.

Abstract: Disclosed is a runner for a Francis-type hydraulic turbine, comprising a ring, a hub, and a number of blades all having a curved shape and being attached to the ring and hub. Each blade has an inlet edge and an outlet edge. The blades are characterized in that, in the direction of turbine rotation, the junction point of each blade inlet edge at the ring is located forwardly of the inlet edge attachment point for that blade at the hub, and the junction point of each blade outlet edge at the hub is located forwardly of the outlet edge attachment point for that blade at the ring.

Abstract: A bi-directional fan includes asymmetrically-shaped fan blades wherein, at each transverse cross-section of the blade, the profile of the blade includes a leading portion lying on one side of a straight line connecting the leading and trailing edges of the blade and a trailing portion lying on the opposite side of the straight line. The leading portion of the blade is larger than the trailing portion of the blade, and the point at which the blade's mean line of profile crosses the straight line is closer to the trailing edge than the leading edge. From the leading edge to a point of maximum camber, the shape of the profile of the blade is described by a polynomial expression. From the point of maximum camber to the trailing edge, the shape of the profile of the blade is described by a cosine wave function. The larger leading portion presents a greater forward-curved surface area which allows the blade to move air more efficiently in the forward direction.

Abstract: In an axial fan having a plurality of blades (2, 2, . . . ) around an outer periphery of a hub (1), a cross-sectional configuration of each of the blades (2) at an arbitrary distance from a center of the fan is set such that a blade thickness gradually increases moving away from a blade leading edge (2a) and then gradually decreases towards a blade trailing edge (2b). Also, if a length of a camber line extending from the blade leading edge (2a) to a position where the blade thickness becomes maximum is taken to be L, and a length of a camber line extending from the blade leading edge (2a) to the blade trailing edge (2b) at the arbitrary distance is taken to be L.sub.0, then L/L.sub.0 falls within a range of 0.27 to 0.35. Thus, the aerodynamic performance never lowers even if the inflow angle of air into the blade (2) varies.

Abstract: A high aspect ratio, low solidity fan blade of an axial flow air cycle machine has a local tip center of gravity axis that has been shifted ahead of an elastic axis. The center of gravity axis can be shifted by clipping the tip of the blade at the trailing edge, by undercutting a rear portion of the pressure surface, or by sweeping forward leading and trailing edges of the blade by about five degrees (without clipping or undercutting the blade).

Abstract: An axial fan for a cooling blower of a vehicle engine has fins with leading and trailing edges, and aeroacoustic optimization is provided by each of the leading edges and trailing edges having a strong forward sweep followed by a strong backward sweep in the manner of a bird's wing or by a straight forward sweeps followed by a strong backward sweep.

Abstract: An energy conversion apparatus for extracting useful energy from moving fluids such as water, the apparatus including a shaft and a plurality of integrally formed blade modules which are coupled together to form the shaft, a plurality of blades is integrally formed on the free ends of arms, the arrangement being such that the blades can be resiliently displaced relative to the arms when located in the moving fluid to thereby produce useful torque on the shaft.

Abstract: An airfoiled blade for improving the performance of a propeller at low aircraft speeds and for maintaining good performance of the propeller at high aircraft speeds is disclosed. The blade comprises a root portion for connection to a hub of the propeller and a tip portion defining an opposite end of the root portion. An elongated portion extends between the base portion and the tip portion and defines a leading edge and a trailing edge. The elongated portion has a cross-section defined by a scaleable airfoil section. The scaleable airfoil section comprises a chord having a fifty-percent chord station, a forward end defining the leading edge of the blade and an aft end defining the trailing edge. The airfoil section is aft end loaded for developing aft end lift. The scaleable airfoil section also has a camber distribution and a thickness distribution based therefrom.

Abstract: A mixed flow fan and heat exchanger assembly is "blow through" in that the fan discharges air into the upstream face of the heat exchanger which provides a flow resistance. The fan is mixed flow so that there are both axial and significant radial components to the air flow exiting the fan impeller. The radial components result in a static pressure facilitating flow through the heat exchanger. The assembly includes an impeller having a generally cylindrical hub and a number of backwardly swept blades. The impeller has an outlet swept radius that is greater than its inlet swept radius. A shroud encloses the impeller and guides the air flow into the impeller and to the heat exchanger. The cylindrical hub and a blade apparent solidity of less than one make the fan impeller adaptable to manufacturing in a single piece by a molding process. In a second embodiment there is a downstream blockage and the radial components to the air flow reduce impingement upon the blockage.

Abstract: A swept turbomachinery blade for use in a cascade of such blades is disclosed. The blade (12) has an airfoil (22) uniquely swept so that an endwall shock (64) of limited radial extent and a passage shock (66) are coincident and a working medium (48) flowing through interblade passages (50) is subjected to a single coincident shock rather than the individual shocks. In one embodiment of the invention the forwardmost extremity of the airfoil defines an inner transition point (40) located at an inner transition radius r.sub.t -inner. The sweep angle of the airfoil is nondecreasing with increasing radius from the inner transition radius to an outer transition radius r.sub.t-outer, radially inward of the airfoil tip (26), and is nonincreasing with increasing radius between the outer transition radius and the airfoil tip.

Abstract: A blade for a vehicle engine-cooling fan assembly having a curved planform and a high-lift airfoil. The planform has a first region adjacent the root of the blade with forward curvature, a second region adjacent the tip of the blade with backward curvature, and an intermediate region disposed between the first region and the second region with substantially straight curvature. The airfoil has a leading edge; a rounded, bulbous nose section adjacent the leading edge; a trailing edge; a curved pressure surface extending smoothly and without discontinuity from the nose section to the trailing edge; a curved suction surface extending smoothly and without discontinuity from the nose section to the trailing edge; and a thin, highly cambered aft section formed adjacent the trailing edge and between the pressure surface and the suction surface.

Abstract: A rotor blade for a rotary-wing aircraft, of an airfoil section has a basic blade thickness at 12% chord length, a portion of an increased blade thickness between the leading edge and a point corresponding to about 90% chord length, a maximum blade thickness at a position shifted backward, a curvature distribution concentrated on the middle portion thereof, and a portion contiguous with the trailing edge and cambered. The drag coefficient of the airfoil section is small when the Mach number is about 0.6 and the lift coefficient is about 0.6, and the airfoil section has a large maximum lift coefficient and a large zero-lift drag divergence Mach number, and generates a small pitching moment.

Abstract: An airfoil defining the shape of the blades of a vehicle engine-cooling fan assembly. The airfoil has a leading edge; a rounded, bulbous nose section adjacent the leading edge; a trailing edge; a curved pressure surface extending smoothly and without discontinuity from the nose section to the trailing edge; a curved suction surface extending smoothly and without discontinuity from the nose section to the trailing edge; and a thin aft section formed adjacent the trailing edge and between the pressure surface and the suction surface. The aft section has a camber at its location of maximum camber of between 5 and 12% of the chord of the airfoil.

Abstract: A forward-swept, low-noise rotor blade includes an inboard section, an aft-swept section and a forward-swept outboard section. The rotor blade reduces the noise of rotorcraft, including both standard helicopters and advanced systems such as tiltrotors. The primary noise reduction feature is the forward sweep of the planform over a large portion of the outer blade radius. The rotor blade also includes an aft-swept section. The purpose of the aft-swept region is to provide a partial balance to pitching moments produced by the outboard forward-swept portion of the blade. The rotor blade has a constant chord width; or has a chord width which decreases linearly along the entire blade span; or combines constant and decreasing chord widths, wherein the blade is of constant chord width from the blade root to a certain location on the rotor blade, then decreases linearly to the blade tip thereafter. The noise source showing maximum noise reduction is blade-vortex interaction (BVI) noise.

Abstract: A ceiling fan is disclosed as including a reversible motor and a plurality of fan blades, each of which is contoured on both its upper and lower surfaces whereby the air flow is directed in accordance to the direction of rotation of the motor, and wherein the fan is located adjacent to its supporting ceiling.

Abstract: A vertical-axis wind turbine includes two or more elongated blades connected to a rotor tower. The tower defines an axis of rotation and is linked, preferably via a gearbox or other torque-converting arrangement, to the shaft of a generator. Each blade is "twisted" so that its lower attachment point is displaced angularly relative to its upper attachment point. In a preferred embodiment, the radial distance of each blade from the axis of rotation varies between upper and lower attachment points such that the blade lies approximately along a "troposkein", which is the shape assumed by a string clamped at each end and spun about an axis passing through the ends of the string. The ratio between blade chord length and blade thickness is preferably constant over the length of each blade, with the middle of each blade approximately 80% as thick as its ends. The cross-section of the blades may be teardrop-shaped, shaped as an airfoil, rectangular, or curved in some other way.

Abstract: A high efficiency exhauster which is capable of attaining operating efficiencies of up to 70% when employed in a solid fuel pulverizer firing system that includes a pulverizer which is operative to effect the pulverization therewithin of the solid fuel supplied thereto and a furnace into which the pulverized solid fuel is injected for combustion therewithin. The high efficiency exhauster includes a casing, an inlet ring supported on the casing, a rotor mounted on the casing for rotation therewithin, a multiplicity of blades, each of a preestablished length and width, mounted in spaced relation one to another on the circumference of the rotor so as to extend at a preestablished angle, and an outlet formed in the casing.

Abstract: A steam turbine blade is provided in which the geometry of the blade airfoil is configured to reduce the weight of the blade while maintaining adequate thermodynamic performance. The blade has a high camber angle to increase its stiffness and an airfoil portion having pressure and suction surfaces. The curvature of the portion of the pressure surface between the base and 75% blade height has a point of inflection in an area adjacent the leading edge so that the curvature switches sign. The curvature upstream of the point of inflection is concave, while the curvature downstream of the point of inflection is convex.

Abstract: A steam turbine blade is provided in which the geometry of the blade airfoil is configured to reduce the weight of the blade while maintaining adequate thermodynamic performance. The blade has a high camber angle to increase its stiffness and an airfoil portion having pressure and suction surfaces. The curvature of the portion of the pressure surface between 25% and 75% blade height has a point of inflection in an area adjacent the leading edge so that the curvature switches sign. The curvature upstream of the point of inflection is concave, while the curvature downstream of the point of inflection is convex.

Abstract: A low noise axial flow fan (10/110) having a plurality of identical blades (13/113) extending from a central hub (11/111). In a preferred embodiment, each blade is highly skewed, having a backward (with respect to fan rotation direction) skew in the root portion (15/115) of the blade nearest the hub, changing to a highly forward skew in the portion (16/116) of the blade near the tip. The fan may be shrouded or unshrouded. In the shrouded embodiment, the fan (110) is used in conjuncton with an inlet orifice structure (131). Each blade of the fan has a chord length (Ch) that increases from root (17/117) to tip (18/118), a pitch angle (.GAMMA.) that decreases from roto to tip and a camber angle (Ca) that decreases from root to tip. In the shrouded embodiment (110), both the contour of the inlet portion (126) of the shroud and the contour of the inlet portion (132) of the orifice structure are quarter sections of ellipses.

Abstract: The fan has an outer circular band that is spaced axially rearwardly of the hub. Forwardly skewed blades extend between the band and hub. Each blade has a radially intermediate portion that has reverse curvatures, namely a radially inner section curving about a location that is axially rearwardly of the blade and a radially outer section curving about a location that is axially forwardly of the blade. The fan is disposed within an aperture of a shroud having a central mount for an electric motor that drives the fan. The shroud has radial members that extend from the edge of the shroud aperture to the hub and that contain an axial offset.

Abstract: An agitator for a clothes washer includes a base and a plurality of blades projecting generally radially outwardly along the base. Each blade, which is of generally S-shape as viewed in plan, includes first and second sides which are of mutually different inclinations with respect to vertical. The first side is of steeper inclination than the second side along a radially inner portion of the blade, and is of less steep inclination than the second side along a radially outer portion of the blade. As viewed in plan, each blade is generally convexly shaped along its radially inner portion and generally concavely shaped along its radially outer portion.

Abstract: A marine propeller includes a hub rotatable about a longitudinal axis and having a plurality of blades extending radially outwardly therefrom and pivotable about respective radial pivot axes between a low pitch position and a high pitch position. Each blade has a hydrodynamic force characteristic which shifts the location of the resultant hydrodynamic force on the blade in a direction aiding up-pitching of the blade, and increasing the up-pitching pivot moment with decreasing angles of attack. A counteractive hydrodynamic force generating area is provided on the negative pressure backside surface of the blade and shifts the location of the resultant hydrodynamic force on the frontside surface forwardly with decreasing angle of attack.

Abstract: A helicoper rotor blade includes at its outer end a tip vane having a mean chord length greater than fifty percent of a chord length of a blade central portion and a span length greater than fifty percent of the blade chord which in operation generates two approximately equal strength tip vortices to reduce an acoustic impulse and a resulting noise known as blade slap.

Abstract: A propeller blade element which virtually eliminates stall conditions. The rotatably driven blade element employs a long straight extended sharp leading edge from hub to tip, without helix, to insure blade laminar fluid flow without vortice formation or leading edge stagnation. The extending leading edge provides separated upper and lower laminar air flow to a "C" shaped blade configuration. The blade element in one form employs a proportionally upwardly curved trailing edge which provides accelerated flow of the high pressure air on the face of the blade, thus increasing the thrust over conventional blade elements.

Abstract: The known rotor blade for use with axial-flow machines is improved. The improvement resides in a novel configuration of the blade body of the rotor blade. A leading edge of a tip end portion of the blade body is inclined forward (in the upstream direction of flow) and also advances in a direction of rotation, towards a tip end surface of the blade body. In the tip end portion between the tip end surface and a cross section displaced from the tip end surface towards the central portion of the blade body by 1/2 of a chord length of the tip end surface, the configuration of the leading edge of the tip end portion is such that an angle S of skew thereof over which the leading edge of the tip end portion advances in the direction of rotation and an effective skew amount .THETA..sub.s eff thereof of the angle over which the leading edge of the tip end portion is inclined forward in the upstream direction falls in a particular region in a graph of S vs. .THETA..sub.

Abstract: Impellers and impeller systems are described which enable liquids and liquid suspensions to be mixed and blended where the size of the impeller and the viscosity of the liquid may require operation in the turbulent and laminar flow regimes, as well as in the transitional flow regime therebetween. The impellers have a plurality of fluidfoil blades and have camber and twist. The geometric pitch or blade angle increases from the tip of the blade towards their axis of rotation in a manner to provide an over pitched condition so that the pitch ratio of the blades at 40% of the blade radius from the axis is greater than the pitch ratio at the tip. The blades are preferably smoothly tapered and increased in width from the tip towards the axis. The impeller blades are mounted on a hub connected to a drive shaft. The blades may decrease in width where they connect to the hub. The pitch angle at the tip is in the range of 18.degree. to 30.degree. (preferably about 20.degree.).

Abstract: A family of airfoils for use in a high solidity factor blade having a leading edge portion and a trailing edge portion, a tip portion, and a root portion, has a plurality of airfoil sections. Each section has: one of any of a plurality of camber lines extending from the leading edge portion to the trailing edge portion, the camber lines being scalable relative to each other, each having the same relative shape, the camber lines having a minimal slope from the leading edge to about a 40% chord and an apogee at about a 74% chord; a scalable thickness ratio of between about 2% to about 7.5%; and, a maximum thickness position which is located from about a 37.5% chord for an airfoil at the tip portion of the blade to about a 35.0% chord for an airfoil at the root portion of the blade.

Abstract: An axial flow ring fan has improved efficiency and reduced noise by making the leading edge of each blade a generally sinusoidal shape and projecting this geometry throughout the blade by imparting fall off to each blade.

Abstract: This invention relates to a section for shrouded propeller blade, of which the relative thickness is included between 9% and 15%, wherein, the curvature of said section having a maximum value at the leading edge thereof, the upper surface line comprises three successive portions, such thatin the first portion, the curvature decreases rapidly from said maximum value at the leading edge to a value close to 20 at a first point of which the reduced abscissa is close to 1%;in the second portion, the curvature decreases more slowly from said value close to 20 at said first point up to a value close to 1 at a second point, of which the reduced abscissa is close to 25%; andin the third portion, the curvature is less than 1 between said second point and said trailing edge.

Abstract: A vertical axis wind turbine blade comprising a blade body with a leading edge and trailing edge there between being generally parallel to each other with a series of a given intersecting triangulation of troughs along the enire blade length with each trough so intersecting transversally the trailing edge and being a upwardly given taper in direction of the leading edge by approximately 80 percent of the blade width and therewithal each trough is formed into a wind channelling containment of equispaced troughs there upon being adjacent with each other along the blade length and with the trough width therein respectively changing the wind driven air columns for a maximum transferring of energy to the blades on the windward side by a higher pressure building up while going into the troughs, while there about on the opposite side there is a reversal type of effect being cause by a pressure drop across the troughs by a lowering of air pressure flows into the troughs to therein cause an effect of speeding up the v

Abstract: A propeller having blades designed to achieve maximum thrust at lower static velocities in both forward and reverse pitch modes is disclosed. Each blade has a generous leading edge radius leading to an upper surface having positive camber and a lower surface having positive camber adjacent the leading edge and negative camber adjacent the trailing edge. Each blade also has a high thickness-to-chord ratio and lower span-to-chord ratio or aspect ratio. This thicker blade profile and aft loading leads to a more uniform pressure distribution and laminar airflow across the blade surface resulting in a higher coefficient of lift, increased blade life and reliability, and lower noise levels.

Abstract: A blade has a plurality of relatively thick, super critical airfoil sections, each section having a parabolic leading edge, with a slight camber extending to about a 40% chord, a gradual upper surface pressure recovery region from the 40% chord to the trailing edge, and a concave lower surface from the 40% chord to the trailing edge to generate required lift. The sections, which have a thickness ratio from about 2% to 7.5%, each have a maximum thickness at approximately 0.36 x/c and a maximum camber at approximately 0.74 x/c, wherein x/c is a dimensionless length along the chord of each of said airfoil sections.

Abstract: A blade is comprised of a plurality of a family of airfoil sections, each section being characterized by a large leading edge radii, a camber having an apogee at approximately 45% of the airfoil section chord length and relatively blunt trailing edge. The airfoil sections taper in thickness ratio (h/b) from about 20% near the blade root to about 2% near the blade tip. The maximum thickness for each airfoil section increases along the chord length from about 39% of the airfoil section for a 20% airfoil section to about 42% of the airfoil section chord length of a 2% airfoil section. As such, the novel blade of the invention provides superior aerodynamic performance to the NACA Series 16 airfoil in the Mach 0.50 to 0.70 range with less susceptibility to foreign object damage and handling problems.

Abstract: A rotating impeller for stirring liquids contained in tanks. Strip-like blades of simple form radiate from a central hub, in swept-back configuration relative to the direction of rotation. The blades are angled relative to the hub so as to exert a forward and downward force upon the liquid as the impeller rotates, and the blade curvature is such that the area projected upon the liquid by the solid structure of the rotating blade is less than the corresponding area that would be projected by an otherwise similar blade in which imaginary straight lines connected all adjacent vertices, and any void areas lying within the boundaries of those imaginary lines had been filled in. The preferred arrangement of the blades is such that when the impeller is arranged with its axis vertical, curvature of each blade along its length is such that it extends away from the hub in a diminishing downward curve, reaches a lowest point, and then rises again before the blade tip is reached.

Abstract: A gas turbine having internal cooling and method of operating the same includes the bypassing of a portion of the cool air from the compressor section into the turbine section along the suction side of the turbine blades while maintaining stable flow conditions in which there is relatively low intermixing between the cool airflow on the suction side and the hot gases on the pressure side.

Abstract: A family of airfoil cross sections, termed SC21xx, for use in a helicopter blade is disclosed. The airfoil (36) achieves maximum lift performance equivalent to prior art airfoil configurations without incurring increased aerodynamic drag at high velocities. The airfoil (36) was developed by thickening and drooping the leading edge region (38) of the prior art airfoil (30) improving lift in the leading edge region (38) and delaying the formation of sonic shock waves at high velocities.

Abstract: The invention relates to a boat propeller unit with double, counter-rotating propellers. The forward propeller is designed to function without cavitation, while the after-propeller is optimally cavitating by being made cupped and with a blade width of between 60% and 75% of the blade width of the forward propeller.

Abstract: A propeller having blades, designed to achieve maximum thrust at lower static velocities in both forward and reverse pitch modes is disclosed. Each blade has a generous leading edge radius leading to an upper surface having positive camber and a lower surface having positive camber adjacent the leading edge and negative camber adjacent the trailing edge. Each blade also has a high thickness-to-chord ratio and lower span-to-chord ratio or aspect ratio. This thicker blade profile and aft loading leads to a more uniform pressure distribution and laminar airflow across the blade surface resulting in a higher coefficient of lift, increased blade life and reliability, and lower noise levels.

Abstract: A rotating impeller for stirring liquids contained in tanks. Strip-like blades of simple form radiate from a central hub, in swept-back configuration relative to the direction of rotation. The blades are angled relative to the hub so as to exert a forward and downward force upon the liquid as the impeller rotates, and the blade curvature is such that the area projected upon the liquid by the solid structure of the rotating blade is less than the corresponding area that would be projected by an otherwise similar blade in which imaginary straight lines connected all adjacent vertices, and any void areas lying within the boundaries of those imaginary lines had been filled in. The preferred arrangement of the blades is such that when the impeller is arranged with its axis vertical, curvature of each blade along its length is such that it extends away from the hub in a diminishing downward curve, reaches a lowest point, and then rises again before the blade tip is reached.