Abstract: An axial flow fan comprising a printed circuit board which mounts the circuitry for operating the motor which is a bipolar winding motor. A voltage regulator IC and a driving IC for a bipolar winding motor are mounted on the printed circuit board. The fan housing is employed as a heat sink for the voltage regulator. Large circuit elements are eliminated. The axial flow fan further comprises a plurality of blades for cooling electronic components wherein the blades comprise of a plurality of specially designed airfoil sections, each section having along substantially the entire length thereof, a cross-sectional shape characterized by a maximum thickness located substantially constantly between about 19% chord to about 20% chord and a maximum camber located substantially constantly between about 45% chord to about 46% chord. The circuitry, housing, and blades are designed so that the axial width of the axial fan is decreased while maintaining performance parameters and design constraints.

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: The present invention provides a fan (100) that includes a hub (102) and a plurality of blades (104). The hub (102) has a blade attachment surface (106) that extends around the circumference of the hub (102). The blades (104) extend from the blade attachment surface (106). Each of the blades (104) has a blade tip (108) distal from the blade attachment surface (106) and a chord length (110) defined as the width of the blade (104). Each blade (104) includes a hub chord length (112) defined as the chord length of the blade (104) at the blade attachment surface (106) and a tip chord length defined as the chord length at the blade tip (108). The relationship of the chord length to the blade radius is defined as the area bounded by the following equations:blade radius=0.0205 metersblade radius=0.0369 meterschord length=0.438*(blade radius)+0.021 mchord length=0.438*(blade radius)+0.028 m,and the blade angle is defined as the area bounded by the following equations:blade radius=0.0205 metersblade radius=0.

Abstract: A swept fan blade design for the low pressure compressor rotor or fan rotor stage of a ducted fan gas turbine engine has a leading edge swept forward near the hub up to a first radial height, then rearward up to second radial height and finally is swept forward again up to the blade tip. The aerodynamic effect is to produce a mid-height bias to the airflow enabling the tip region to be given increased twist and to possess increased resistance to foreign object damage. The design also provides a rear radial blade stacking axis to help reduce internal stresses due to centrifugal forces.

Abstract: Airfoils for the tip and mid-span regions of a wind turbine blade have upper surface and lower surface shapes and contours between a leading edge and a trailing edge that minimize roughness effects of the airfoil and provide maximum lift coefficients that are largely insensitive to roughness effects. The airfoil in one embodiment is shaped and contoured to have a thickness in a range of about fourteen to seventeen percent, a Reynolds number in a range of about 1,500,000 to 2,000,000, and a maximum lift coefficient in a range of about 1.4 to 1.5. In another embodiment, the airfoil is shaped and contoured to have a thickness in a range of about fourteen percent to sixteen percent, a Reynolds number in a range of about 1,500,000 to 3,000,000, and a maximum lift coefficient in a range of about 0.7 to 1.5. Another embodiment of the airfoil is shaped and contoured to have a Reynolds in a range of about 1,500,000 to 4,000,000, and a maximum lift coefficient in a range of about 1.0 to 1.5.

Abstract: A high efficiency axial flow fan includes a hub, fan blades and a circular band. The hub rotates about a rotational axis when torque is applied from a shaft rotatably driven by a power source. The circular band is concentric with the hub, connected to the tip of each blade, and is spaced radially outward from the hub. The blades are configured to produce an airflow when rotated about the rotational axis. Each blade has a chord length distribution, stagger angle and dihedral (axial) distance which varies along the length of the blade. The dihedral distance of each blade varies as a function of blade radius from the rotational axis.

Abstract: An optimum axial distance is secured by varying the distance between a nozzle blade and a moving blade along the length of a nozzle blade (11). The nozzle blades (11) are curved so that a middle portion of each nozzle blade has a section (b2) dislocated in the flowing direction of a fluid which flows through the fluid passage relative to the root section (b3) and the tip section (b1) of the blade with respect to a circumferential direction and an axial direction. Outlet flow angle of the nozzle is varied with distance along the blade length to vary optimum axial distance properly.

Abstract: A variable speed helicopter rotor system and method for operating such a system are provided which allow the helicopter rotor to be operated at an optimal angular velocity in revolutions per minute (RPM) minimizing the power required to turn the rotor and thereby resulting in helicopter performance efficiency improvements, reduction in noise, and improvements in rotor, helicopter transmission and engine life. The system and method provide for an increase in helicopter endurance and. The system and method also provide a substantial improvement in helicopter performance during take-off, hover and maneuver.

Abstract: The present invention relates to a blade with a swept-back tip for a rotary wings of an aircraft, a blade being formed of successive elemental cross sections. The blade is divided into different regions, with the chord length L and the offset y'f of the center of pressure from the pitch-change axis and the relative thickness of each elemental section are optimized for high-speed flight. The first region has a linearly increasing chord length, the second region has the maximum and constant chord length, the third region has a linearly decreasing chord length and the fourth region has a decreasing chord length according to a parabolic function. The offset of the aerodynamic center is positive and increases in proportional to the distance in the first region, is at its maximum and constant in the second region, and decreases linearly and become negative in the third region.

Abstract: A first-stage turbine blade includes an airfoil having a profile according to Table I. The airfoil has a plurality of cooling air passages extending linearly from the root portion to the tip portion of the airfoil. The blade includes a shank having a pair of cavities in communication through the blade dovetail with a plenum in the wheel space for supplying cooling air to the passages in the airfoil. The cooling passages in the airfoil terminate in a recess at the tip portion which has an opening adjacent the trailing edge of the airfoil and along the suction side to enable egress of cooling air into the hot gas stream on the low pressure side of the airfoil. The majority of the cooling passages are turbulated. Certain of those passages are arranged in rows lying adjacent to the pressure and suction sides of the airfoil.

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: The coordinates defining the upper surface, lower surface, leading edge configuration and center of circle for a helicopter blade airfoil are given to increase maximum lift coefficient and lift-to-drag ratio, and to reduce noise level.

Abstract: In a helicopter blade aerofoil, upper and lower surfaces thereof are defined by the following coordinates, and the leading edge profile of the aerofoil is defined by the following leading edge radius and center of circle. Thus drag divergence Mach number Mdd and maximum lift coefficient Clmax can be increased and the level of noise can be reduced.______________________________________ X/C Yup/C Ylow/C ______________________________________ 0.00000 0.00000 0.00000 0.00250 0.00781 -0.00558 0.00500 0.01131 -0.00765 0.00750 0.01423 -0.00874 0.01000 0.01660 -0.00964 0.01750 0.02224 -0.01156 0.02500 0.02658 -0.01276 0.50000 0.03585 -0.01568 0.07500 0.04128 -0.01758 0.10000 0.04480 -0.01901 0.15000 0.04893 -0.02113 0.20000 0.05095 -0.02306 0.25000 0.05181 -0.02492 0.30000 0.05200 -0.02647 0.35000 0.05179 -0.02760 0.40000 0.05129 -0.02821 0.45000 0.05038 -0.02827 0.50000 0.04888 -0.02775 0.55000 0.04673 -0.02662 0.60000 0.04393 -0.02491 0.65000 0.04037 -0.02268 0.70000 0.03592 -0.01996 0.75000 0.03052 -0.01682 0.

Abstract: A mixing process may be carried out in a tank of a certain diameter. The process may also be constrained to the use of an impeller of certain diameter in order to obtain the flow pattern desired to carry out the process. The power consumption of the system which may be expressed in terms of flow per unit (Q/P) is optimized for the impeller diameter to tank diameter (D/T) constraint by utilizing an axial flow blade, preferably having camber and a tip chord angle at the tip and an angle near the attachment to the shaft (the hub) which rotates the impeller, where the tip chord angle and the twist the difference between the blade angle (between the chord and a plane perpendicular to the axis of rotation of the shaft between the tip and hub) are varied in opposite senses; for example, increasing the tip chord angle to provide a more D/T for a more optimum Q/P to which the process is constrained and then reducing the twist to maintain the power efficiency at the higher tip chord angle.

Abstract: A high efficiency, low solidity, low weight, axial flow fan (100, 200, 300) includes a hub (102, 202, 302), fan blades (104, 204, 304) and a circular band (106, 206, 306). The hub (102, 202, 302) rotates about a rotational axis (110, 210, 310) when torque is applied from a shaft (not shown) rotatably driven by a power source (not shown). The circular band (106, 206, 306) is concentric with the hub (102, 202, 302) and is spaced radially outward from the hub. The blades (104, 204, 304) are distributed circumferentially around the hub (102, 202, 302) and extend radially from the hub to the circular band (106, 206, 306). The blades (104, 204, 304) are configured to produce an airflow when rotated about the rotational axis (110, 210, 310). Each blade (104, 204, 304) has a chord length distribution which varies along the length of the blade, such that the chord length has a local minimum value at a predetermined location between the ends of the blade.

Abstract: A main rotor is provided for use on a model helicopter. The main rotor includes rotor blades having an inboard section and an outboard section. The inboard section includes a higher camber, thin, wide airfoils, and greater pitch and camber relative to the outboard section. The outboard section includes an average chord length that is less than the chord length of the inboard section, The rotor blades also include a blade body that is semiflexible to bend during a crash landing of the model helicopter.

Abstract: An axial-flow impeller having a maximum blade width less than 20% of the impeller diameter, the pitch angle at the radial position 0.6 is 12.degree.-22.degree., the width at the tip end portion of the blade is 12-75% of the width at the radial position 0.6, the pitch angle at the tip end portion of the blade is 5.degree.-10.degree. smaller than the pitch angle at the radial position 0.6, the width at the root of the blade is 40% or more of the width at the radial position 0.6, and the pitch angle at the root of the blade is 25.degree.-50.degree.. An axial-flow impeller having a maximum width of the blade 20% or more of the impeller diameter, the radial position of the maximum width portion is 0.4-0.8, the pitch angle of the maximum width portion is 12.degree.-22.degree., the width at the tip end portion of the blade is 12-75% of the maximum width, and the pitch angle at the tip end portion of the blade is 5.degree.-10.degree.

Abstract: An airfoiled blade is disclosed which comprises a plurality of airfoil sections, a root portion, and a tip portion. Each section has along substantially the entire length thereof a cross-sectional airfoil shape characterized by a parabolic leading edge, a front loading and a blunt trailing edge. Each of the airfoil sections has a chord passing therethrough with a 50% point and a maximum thickness forward of the 50% point, toward the leading edge. A thickness ratio range from a first of the airfoil sections nearest the tip portion to a last of the airfoil sections nearest the root portion of substantially 3% to 28% is preferred. In one embodiment, the blade further includes a second airfoil section, a third airfoil section and a fourth airfoil section located between the first and last airfoil sections. The first airfoil section has a thickness ratio of substantially 3.3%, the second airfoil section has a thickness ratio of substantially 4.1%, the airfoil section has a thickness ratio of substantially 7.

Abstract: A blade for a vehicle engine-cooling fan assembly. The blade combines a particular distribution of four, key, blade-design parameters--planform sweep, airfoil chord, maximum airfoil camber, and airfoil pitch angle--to achieve a fan assembly having high pumping, high efficiency, and low noise. Specifically, the blade has a planform with a forward sweep angle continuously increasing in absolute value along the span from the root to a maximum absolute value not exceeding about 15 degrees at the tip. The airfoil of the blade has a chord that continuously increases from the root to the tip, a maximum camber that continuously decreases from a value not greater than about 12% of chord at the root to a value not less than about 5% of chord at the tip, and a solidity not greater than about 1.1 at the root and not less than about 0.5 at the tip.

Abstract: A centrifugal ventilator fan having a base plate with an axis of rotation, an inlet ring having an opening therethrough and a plurality of generally flat blades, each having first and second side edges, a leading edge and a trailing edge is provided. Each blade is connected to the base plate along the first side edge, and is connected to the inlet ring along the second side edge. The blades are radially spaced about the axis of rotation and are backwardly inclined with respect to a direction of rotation of the fan. A portion of each blade adjacent to the leading edge has a radius of curvature such that the blade portion adjacent to the leading edge extends generally inwardly towards the axis of rotation to reduce noise generated by the ventilator fan.

Abstract: Aerofoil members such as the stator vanes and rotor blades of an axial flow compressor are defined by a number of nominal sections. The leading edge of each nominal section of the blade is set so that an airflow passing therethrough is incident at the optimum angle. The optimum angle is chosen so that the maximum velocities of the airflow at the leading edge are equal. Once the optimum angle has been found for each section of the blade the sections are stacked to define a blade having a leading edge the aerodynamic profile of which ensures that the airflow is incident at the optimum angle along the length of the blade from the root to the tip. The efficiency of the axial flow compressor is improved.

Abstract: This invention relates to a method to dertermine the shape of a fan blade of a sirocco fan which can improve fan efficiency and reduce the noise from flow, comprising the steps of determinating a camber line and, upper surface and lower surface of the blade by equations which define mean line and thickness distribution of NACA wing sections, respectively and determinating maximum ordinate of the camber line by following equation;Ta=2m/pwhere, Ta is leading edge angle,m is maximum ordinate of mean line and,p is chordwise position of maximum ordinate.

Abstract: Airfoils for the blade of a wind turbine wherein each airfoil is characterized by a thickness in a range from 16%-24% and a maximum lift coefficient designed to be largely insensitive to roughness effects. The airfoils include a family of airfoils for a blade 15 to 25 meters in length, a family of airfoils for a blade 1 to 5 meters in length, and a family of airfoils for a blade 5 to 10 meters in length.

Abstract: A steam turbine blade having an airfoil portion and root portion by which the blade is affixed to a rotor. The geometry of the blade airfoil is configured to minimize energy loss through the row of blades and reduce the weight of the airfoil. The airfoil has a leading edge and a trailing edge defining a chord therebetween. The chord is reduced linearly from the base of the airfoil to 50% of the airfoil height. However, the chord remains essentially constant from 50% of the airfoil height to the airfoil tip. The root is fir tree shaped and has four sets of tangs and grooves that are configured to minimize the stresses in the root.

Abstract: An aircraft variable pitch propeller blade utilized in subsonic flight at relatively slow turning applications with relatively high power coefficients. The blade in plan form is tapered at both ends with the maximum chord approximate the mid station of the blade, the leading edge of the blade being swept behind the longitudinal axis of the blade near its tip and the trailing edge is convex and essentially straight from its maximum chord outward to the tip.

Abstract: A thick airfoil for the root region of the blade of a wind turbine. The airfoil has a thickness in a range from 24%-26% and a Reynolds number in a range from 1,000,000 to 1,800,000. The airfoil has a maximum lift coefficient of 1.4-1.6 that has minimum sensitivity to roughness effects.

Abstract: The variation in the length of the chord L and the variation of the offset Y'f of the aerodynamic center are such that the leading edge (5) and the trailing edge (6) of the blade (1), along its longitudinal extent, exhibit no break, the overall aerodynamic center of said blade Being substantially situated on the pitch variation axis.

Abstract: Conventionally gas turbine engine compressors have fixed inlet guide vanes to give a predetermined swirl to incoming air at an engine design speed, so that air enters the compressor at an optimum angle. At speeds much lower, for example, than the design speed the guide vane is less efficient. The guide vanes are thereby made variable in camber. Each vane comprises a number of spanwise hinged members which can be moved relative one to another to vary the vane camber.

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: A fixed pitch propeller has blades that are not solely dependent on the blade angle dictated by the helical path of the blade tip. An outboard portion of the blade has a range of blade angles that are relatively flat to operate most efficiently at lower aircraft speeds.

Abstract: A low cost assembly and method for assembly of a fan having a hub, a spider with arms and blades attached to the arms is provided. The spider is arc welded to the hub and the blades are projection welded to the arms. The blades have a root, a tip, and an ear. The width or chord of the blade decreases from the root to the ear and then increases from the ear to the tip. The blade has an air foil shape defined by the arcs of two circles. The radii of the circles and, thus the profile of the blade, change as a function of the cord length and the camber of the blade. The blades have a pitch angle which decreases from the root to the ear. The spider arms are formed to match the pitch and are rotated slightly with respect to the horizontal. The result is a highly efficient, low cost fan blade assembly construction.

Abstract: A marine propeller (100) combines progressive pitch with both increasing pitch and increasing progressiveness of pitch along at least a portion of increasing radii from the axis of rotation to the outer blade tip. A five blade propeller is provided which accommodates thermal warpage of the outer blade tips, such that the same propeller includes two different types of blades, one blade having increasing pitch with increasing radii all the way to the outer blade tip, and the other type of blade having increasing pitch to a given radius and then decreasing pitch with increasing radii to the outer blade tip. The latter blade type is preferred and has a hump in the pressure surface at the noted given radius between portions of increasing and decreasing pitch with increasing radii.

Abstract: In an axial fan, the angle of curvature of the median line of each blade in axial projection is nil at the hub and for about one third of the radial extension of the blade from the hub. The blade angle of each blade is substantially constant along the blade and the chord between the leading edge and the trailing edge of each blade is substantially constant along the blade between the hub and the outer ring.

Abstract: A stationary blade of a steam turbine having a rotor and an inner cylinder for mounting the stationary blade in a row with plural identical stationary blades, comprising an airfoil having a leading edge, a trailing edge, a pressure-side concave surface and suction-side convex surface extending between the leading and trailing edges. A stagger angle being defined by as an angle of a chord between the leading and trailing edges to a longitudinal axis of the rotor; an outer ring for connecting a proximal end of the airfoil to the inner cylinder; an inner ring connected to a distal end of the airfoil; and a seal assembly carried by the inner ring and sealingly engaging the rotor; wherein the stagger angle ranges from about 42.degree. at the distal end of the airfoil to about 52.degree. at the proximal end.

Abstract: An aircraft propeller blade utilized in subsonic flight at relatively slow turning applications with relatively high power coefficients. The blade in plan form is tapered at both ends with the maximum chord approximate the 44% percent station of the blade, the leading edge of the blade being swept behind the longitudinal axis of the blade near its tip and the trailing edge is convex and essentially straight from its maximum chord outward to the tip.

Abstract: An axial flow fan operates with increased efficiency, reduced noise, and improved resistance to stall. These benefits are achieved by providing a fan shroud with a bellmouth and a hub with a curved bellmouth wherein both have a substantially parabolic shape, and by providing a blade shape with an air pressure distribution that promotes smooth airflow and resists stall. The blade is provided with a twist that varies with distance from the blade root such that the work done on the air moved by the blade, whether at the blade root or tip, is substantially equal.

Abstract: The invention relates to an axial fan with an essentially cylindrical outer housing and with a fan wheel which rotates therein and the hub of which is located on the rotor of an electric drive motor, the stator of the drive motor being held by webs extending on the delivery side relative to the outer housing. The vanes of the axial fan are radially twisted and possess a forward curvature with a camber varying from the hub cross-section to the outer cross-section. In order to achieve a pressure increase, at the same time with a reduction of the operating noise, the vanes have in the hub region a cross-section designed for a low flow per unit volume and small pressure increase, but in the outer region a cross-section designed for higher values of flow per unit volume and pressure increase.

Abstract: Flow separation behind the notch region of a swept tip of a helicopter rotor blade is reduced by features of the geometry and aerodynamic characteristics of the notch region itself. In particular it has been found beneficial for a forwardly swept leading edge portion to extend at an angle between 30 degrees and 55 degrees from a reference line parallel to a blade pitch change axis and the leading edge of the aerofoil in the notch region incorporates blade droop.

Abstract: A rotor blade includes a root, tip, leading edge, trailing edge, forward surface, and aft surface, and a pitch section disposed equidistantly between the root and tip. The blade has a forward sweep from at least the pitch section to the blade tip relative to incoming streamsurfaces of a fluid flowable over the blade.

Abstract: A quiet tail rotor (QTR) blade for helicopters that provides reduced noise levels and increased thrust efficiency. The QTR blade includes a first segment for connecting the QTR blade to a helicopter tail rotor hub and an outboard segment, integral with the first segment, having a configuration that reduces high speed impulsive noise and blade vortex interaction noise and provides increased thrust efficiency. The outboard segment includes an inboard segment integral with the first segment and a swept, tapered tip segment integral with the inboard segment. The inboard segment has a constant chord and a predetermined constant airfoil section profile defined by constant upper and lower surface contours. The predetermined constant airfoil section profile has a t/c ratio greater than about twelve percent of the chord at any station. The swept, tapered tip segment has a variable chord and a predetermined airfoil section profile defined by constant upper and lower surface contours.

Abstract: A marine propeller (100) combines progressive pitch with both increasing pitch and increasing progressiveness of pitch along at least a portion of increasing radii from the axis of rotation to the outer blade tip. A five blade propeller is provided which accommodates thermal warpage of the outer blade tips, such that the same propeller includes two different types of blades, one blade having increasing pitch with increasing radii all the way to the outer blade tip, and the other type of blade having increasing pitch to a given radius and then decreasing pitch with increasing radii to the outer blade tip. The latter blade type is preferred and has a hump in the pressure surface at the noted given radius between portions of increasing and decreasing pitch with increasing radii.

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: A high efficiency impeller has blades which are formed of plate material. Each blade has a first span-wise bend which extends generally parallel to the trailing edge and through about the center of the blade measured cord-wise and extending the length of the blade from the root end to the tip end. The first bend divides the blade into a back portion and a front portion. The front portion is further divided by a second bend line which extends from the intersection of the first bend line with the tip of the blade diagonally to the leading edge of the blade at a point about one-fifth to one-third the span-wise length outwardly from the blade root. The material of the blade is bent about each of the bend lines, in the same direction, to provide camber and concavity for the blade. The leading and trailing edges of the blade are chamfered.

Abstract: A blade is overtwisted in the extremity zone from at least 0.85R so that the resulting twist is at least equal to a limiting twist .theta.limC according to the plane form Co/C(r) of the blade in this zone and so that the lift coefficient Cz has, in a first fraction of the extremity zone extending at least between r=0/85R and r=0.9R, a decreasing value remaining lower than a first limiting value CZlim1=Czm-a(r/R-b), Czm being the mean lift coefficient of the rotor and a and b being experimental constants, and in a second extremity fraction extending between r=0.9R and at least r=0.95R, the lift coefficient continues to decrease by remaining less than or equal to a second limiting value Czlim2 linearly decreasing from the value Czlim1 for r=0.9R as far as the zero value for r=R.

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: To reduce the noise levels of open rotor devices rotating at supersonic tip speeds, a combination of blade sweep and aerofoil profile is employed. The sweep of the blade extends through the sonic radius, and in the region of the sonic radius the section comprises a leading edge profile with a rounded nose conforming essentially to the formulaT.about.x.sub.L.sup.a Lwhere T is the blade thicknessx.sub.L is the distance from the front of the leading edgea.sub.L is an algebraic power greater than 3/4 and less than 1.The leading edge profile extends 2-15% of the aerofoil chord and has a nose radius not greater than 2% of the chord. It can be shown that, by these measures, it is possible to moderate the perceived noise levels from a device such as an aircraft propeller rotating at supersonic tip speeds.

Abstract: An improved gas turbine engine blade having increased resistance to foreign object damage is disclosed. The blade includes a swept-back leading edge portion in the tip region of the blade for improving resistance to tip curl due to foreign object impact.

Abstract: This invention relates to a blade for shrouded propeller, wherein: in plan, its aerodynamically active part presents a rectangular shape; and the maximum relative camber of the successive profiles constituting the aerodynamically active part of the blade increases from a value close to 0 to a value close to 0.04; the twist of the aerodynamically active part of the blade decreases from a first value close to 12.degree. to a second value close to 4.degree., then increases to a third value close to 4.5.degree.; and the maximum relative thickness of said successive profiles decreases from a value close to 13.5% to a value close to 9.5%.

Abstract: Wind turbine apparatus includes a plurality of air foil sail elements secured to a circular frame rotatable in response to wind reacting with the sail elements. The sail elements include deformable outer skin portions, one of which is flattened against an interior form in response to wind forces, and the other of which extends convexly away from the interior form. The deformation changes the camber of the sail element.

Abstract: Multiple flat-plate blade rows of pitch adjustable blades are offset mounted in a manner such that when flat-plate blades in adjacent rows are aligned at a specific pitch setting, respective flat-plate blades of the adjacent rows nearly mate. The offset between the flat-plate blade rows functions to produce unequal pitch angle settings of the blades of adjacent rows which, in turn, function to produce the result that the respective flat-plate blades which nearly mate, in combination, produce a blade configuration which has an effective camber.