Abstract: Determining adjustments for rotating blades includes measuring a plurality of vibration values corresponding to vibrations caused by the blades, providing coefficient of vibration data that corresponds to effects on vibration caused by adjustments to the blades, applying the coefficient of vibration data to the vibration values, and solving for possible values for the adjustments that may be applied to the blades, wherein the possible values for the adjustments are constrained to be greater than a first predetermined value or zero. The adjustments may include at least one of hub weights, blade tabs, PCR adjustments, and blade tip weight adjustments. Measuring vibrations may include obtaining signals from a plurality of accelerometers. Determining adjustments may also include performing an FFT on the vibration data, where the data indicating effects on vibration is provided in the frequency domain. Applying the data to the vibration values may be performed in the frequency domain.

Abstract: An article that is configured to be rotatably mounted includes an embedded hollow cavity into which at least one dampening member is inserted. The dampening member or members frictionally engage the hollow cavity such that relative movement between the dampening member or members and the hollow cavity operates to attenuate vibration that is generated when the article is rotated.

Abstract: A clamp (20, 50) for balancing can be mounted on the circumference of a rotating body (10) on a part (12) that tapers to a thin-walled end. The clamps (20, 50) has a U-shaped cross-sectional profile with at least one tip (28, 30) formed onto one leg (24, 26), which tip protrudes into the interior (36) of the U-shaped cross-sectional profile and extends in inclined fashion toward the connecting part (32) of the legs (24, 26).

Abstract: A rotor for rotary wing aircraft includes a number of features that reduce the collective forces required to control the pitch of the rotor. The spar caps of the spar become joined to one another at the same point where bonding begins between the blade and the spar. The tendency of blade to want to flatten out is minimized since the centrifugal force acting on the spar is located at or near the pitch change axis. Tip weights are located at or near the pitch change axis as well. In a preferred embodiment, the tip weights are located evenly in front of and behind the structural center of the inboard section of the spar. The blade of the rotor and the tip are not swept back.

Abstract: The object of the invention is to improve the efficiency of a turbomachine blade provided with a reinforced hole for accommodating a damping element. To this end, the raised end faces (12, 13) of the marginal region (11), reinforced toward the hole (10), of the blade body (4) are formed with an acute angle (&agr;) open toward the leading edge (5) of the blade body (4) and/or with an acute angle (&bgr;) open toward the blade tip (9).

Abstract: A damper that provides damping for turbine engines to reduce vibrations in the blades, vanes, shrouds, ducting, liner walls and/or other components of the turbine engine. The damper includes an air cavity in a blade, vane, shroud or other engine component and a material covering at least a portion of the air cavity. Vibrations in the turbine engine and its components produce movement of the air inside the air cavity resulting in a corresponding viscous force that dampens the vibrations.

Abstract: The rotor comprises a pendular vibration suppressor with at least two pendulums each having at least one pendular body connected by at least one rigid arm to a support that rotates as one with the rotor hub, and on which the pendulum oscillates via a pivoting connection about an axis of pendular movement spaced away from the center of inertia of the pendulum and from the axis of the rotor, and substantially perpendicular to a radial plane passing through the axis of the rotor and through the center of inertia of the pendulum, which preferably oscillates between two adjacent rotor blades. At least some of the pendulums are tuned to (nb−1)&OHgr; or (nb+1)&OHgr;, so as to attenuate coplanar moments, and other pendulums may be tuned to nb&OHgr;, to filter out forces along the axis of the rotor.

Abstract: A rotor, such as a rotor of an aircraft gas turbine engine, uses damper-ring devices for damping unwanted rotor vibrations. One device has inner and outer damper rings with the outer damper ring providing ring-rotor frictional damping only at large vibrational amplitudes and with the inner and outer damper rings providing inter-ring frictional damping at both small and large vibrational amplitudes. Other devices include a damper ring and a viscoelastic layer, a hollow damper ring containing particulate matter, and a damper ring in the form of a cable made of twisted single-wire strands.

Abstract: A rotor assembly for a gas turbine engine includes a bearing assembly that reduces dynamic loads to a support frame and static bending to the rotor assembly during periods of rotor unbalance. The rotor assembly includes a rotor shaft coupled to a fan and supported longitudinally with a plurality of bearing assemblies on a support frame. A number two bearing assembly includes a paired race, a rolling element, and a mounting race. The mounting race includes a spherical face and is secured to the bearing assembly with a retainer that plastically fails at a pre-determined moment load.

Abstract: Dovetail-shaped grooves are formed in the axial faces and circumferential rims of wheels and spacers forming a rotor body. Complementary-shaped balance weights are inserted through entry apertures in the grooves and circumferentially aligned into adjusted balanced positions. Fasteners are threaded through the weights to engage in slots at circumferentially spaced positions along ribs projecting from the bases of the grooves. By threading the fastener into the slot and staking the fastener to the balance weight, the metal of the rotary component is not upset or deformed, with the result that the potential for development of cracks in the rotary component is substantially reduced.

Abstract: A gas turbine engine blade spacer has an axially extending backbone, spaced apart forward, mid and aft dovetail lands, respectively, disposed along the backbone, the backbone and the forward, mid, and aft dovetail lands having bottom curved backbone surfaces. Each of the forward, mid and aft dovetail lands has a riser that extends above the backbone and has a riser flat top. In the exemplary embodiment disclosed herein, a spacer tab extends generally axially forward of the forward land and includes intersecting axially and radially extending tab apertures. A void extends around the backbone and between the forward and aft dovetail lands and the void is filled with an elastomeric material. The spacer has a constant shape and size cross-section between the forward and aft dovetail lands.

Abstract: A tuning rib is added preferably in the aft cavity of a cored turbine bucket to alter the bucket's natural frequencies. The tuning rib may be a solid rib or a segmented rib and is particularly suited for altering high order frequency modes such as 2T, 4F and 1-3S. As such, detrimental crossings of natural bucket frequencies and gas turbine stimuli can be avoided to thereby improve the reliability of a gas turbine without impacting other features of the bucket that are important to the performance of the gas turbine.

Abstract: The present invention relates to a blade arrangement with damping elements and to a method of damping vibrations of a blade arrangement. The blade arrangement comprises a rotor and blades arranged on the circumference of the rotor. Damping elements (2, 3) are arranged between the blades and are in contact with the blades due to a centrifugal force, acting in the radial direction, during rotation of the rotor. In this case, at least two damping elements (2, 3) are arranged one behind the other in the circumferential direction of the rotor between adjacent blades, which damping elements (2, 3), during rotation of the rotor, come into contact with one another via a contact surface (6), and of which a first damping element (2) comes into contact with a first friction surface (4) of one of the blades and a second damping element (3) comes into contact with a second friction surface (5) of the other blade. A multiplicity of different vibration states can be effectively damped with the blade arrangement.

Abstract: A rotor blade for a turbine engine rotor assembly is provided comprising a root, an airfoil, a platform, and a means for damping vibrations in the airfoil. The airfoil includes a pocket formed into a chordwise surface. The damper is received into the pocket, forming a surface flush with the airfoil. Relative movement between the damper and the airfoil cause vibrational movement to be damped and dissipated in the form of frictional energy.

Abstract: A multi-stage rotor assembly for a gas turbine engine including a damper system that facilitates damping vibrations induced to the rotor assembly is described. The rotor assembly includes a blisk rotor including a plurality of rotor blades and a radially outer rim. The rotor blades are integrally formed with the rim and extend radially outward from the rim. The damper system is attached to rotor blades within at least one stage of the rotor assembly, and includes at least one layer of damping material and a cover sheet. The cover sheet is attached to the rotor blade with adhesive.

Abstract: A multi-stage rotor assembly for a gas turbine engine includes a damper system that facilitates damping vibrations induced to the rotor assembly. The rotor assembly includes a blisk rotor including a plurality of rotor blades and a radially outer rim. The rotor blades are integrally formed with the rim and extend radially outward from the rim. The damper system is attached to rotor blades within at least one stage of the rotor assembly, and includes at least one layer of damping material and a cover sheet. The cover sheet is attached to the rotor blade with adhesive.

Abstract: The present invention relates to an array of flow directing elements having increased flutter stability for use in turbomachinery devices. The array comprises at least one high frequency flow directing element and at least one low frequency flow directing element. In a preferred embodiment, the array comprises a plurality of alternating high frequency and low frequency flow directing elements. Each high frequency flow directing element has its three lowest frequency vibratory modes at least 2.0% higher in frequency than the three lowest frequency vibratory modes of each low frequency flow directing element. The array of the present invention has particular utility in a turbomachinery device as part of a rotor stage.

Abstract: A vibration damper 46 for a gas turbine engine has convergent friction surfaces 48a and 48b and is located radially inward of the platforms 20a and 20b of two adjacent turbine blades. The angle subtended by the friction surfaces 48a and 48b is smaller than that subtended by the angled faces 22a and 22b associated with the platforms 20a and 20b. The center of mass of the damper 46 lies in a plane bisecting the angle subtended by the friction surfaces 48a and 48b. In use the damper 46 is urged radially outwards by centrifugal force so that at least one of the friction surfaces 48a and 48b makes planar contact with at least one of the angled faces 22a and 22b. Vibrational energy is dissipated by the resultant sliding movement between the friction surfaces 48a and 48b and the angled faces 22a and 22b. A secondary vibration damping mechanism arises from the oscillation of the damper 46 between the platforms 20a and 20b.

Abstract: The present invention relates to a method for reducing the blade-vortex interaction noise of rotary wings. According to the invention: at least one value &PSgr;o of the azimuth of the blades (1) is determined, for which value said blades shed tip vortices giving rise to a peak intensity of noise; a trailing edge flap (2) is disposed on each blade (1), the former generating an auxiliary vortex (11), parallel to the tip vortex (10) and attached to a blade section (8) lying between the blade section (7) around which the speed circulation is a maximum and the tip section (3) of said blade; and a deflection is applied to each of said flaps (2) such that, for said value &PSgr;o, the speed circulation around said blade section (8) is a specified fraction of the maximum speed circulation.

Abstract: A one-piece fan rotor optimized for construction and safety performance criteria is provided. The rotor has a hub with a radial cross-section defined by an I-beam. A plurality of unequally-spaced rotor blades are disposed circumferentially around and extend radially outward from the hub. Each rotor blade has a root portion coupled to the hub with the root portion defined by a concave fillet circumventing the rotor blade. For rotational balance, at least one of the forward side and backside of the hub incorporates an axially extending pad. Methods are provided for controlling stress on the rotor and for balancing the rotor.

Abstract: A damping apparatus for damping vibrations in a vibrating system including a piston which is reciprocally movable in a fluid filled chamber, piston movement in either direction of movement being resisted by fluid pressure in the chamber behind the piston, which resistance provides damping forces which act to oppose piston movement, the piston being connected to one component of the vibrating system and the chamber being connected to a second component of the vibrating system, characterised in that structure is provided to relieve the fluid pressure behind the piston to allow substantially unopposed piston movement in the chamber without damping forces being provided, during piston movements which occur in response to vibrations in the vibrating system at frequencies other than a fundamental frequency which the damping apparatus primarily is intended to damp.

Abstract: The present invention relates to a blade assembly with damping elements, which comprises a rotor (5) and blades (6) which are installed on the circumference of the rotor and have a blade platform (7), shank (14) and root (8). A damping element (9) is arranged between respectively adjacent blades (6), said damping element (9) being frictionally connected on rotation of the rotor (5), to at least a first region (1, 2) of a first of the respectively adjacent blades (6), and to a second region (3) of a second of the respectively adjacent blades (6). The blade assembly is characterized by the fact that the damping element (9) is configured and arranged between the first and second blades in such a way that the first region (1, 2) and the second region (3) are located at positions which are significantly spaced apart from one another in the radial direction. This blade assembly provides efficient oscillation damping even in the case of small relative movements between adjacent blades.

Abstract: An article that is configured to be rotatably mounted includes an embedded hollow cavity into which at least one dampening member is inserted. The dampening member or members frictionally engage the hollow cavity such that relative movement between the dampening member or members and the hollow cavity operates to attenuate vibration that is generated when the article is rotated.

Abstract: The blades (3) of a turbine of axial design are inserted into an undercut blade groove (2) of the turbine rotor (1) in a positive-locking manner and are secured by a blade lock. The blade lock comprises a mounting space (7), which is in connection with the blade groove (2) and into which a filler piece (8), which is in positive-locking relationship with the blade foot (6) of the blades (3), and a wedge (9) are inserted. The cross section of the mounting space (7) receiving the filler piece (8) is widened conically beginning from the blade groove (2). The cross section of the filler piece (8) is adapted to the cross section of the mounting space (7).

Abstract: The present invention relates to an improved array of flow directing elements for incorporation in turbomachinery. In accordance with the present invention, an array of flow directing elements comprises a plurality of flow directing elements mounted to a rotor disk. The plurality of flow directing elements includes a first set of first flow directing elements whose natural vibration frequency has been modified by having material removed from a leading edge tip region and a second set of second flow directing elements whose natural vibration frequency has been modified by having material removed from a midspan leading edge region. The array may further comprise unmodified flow directing elements arranged with the modified flow directing elements.

Abstract: A realistic study of high-cycle fatigue in turbo-machinery is dependent on a means of reproducing, in an evacuated test facility, the vibration of turbine blades caused by inhomogeneous flow in the engine. An apparatus and method are described which use magnetic eddy currents to generate such vibration. The apparatus makes use of an array of magnets to produce blade vibration of the magnitude and period characteristic for turbo-machines.

Abstract: A passive device is provided for reducing vibration and noise in a hydraulic system. The passive device includes a tubular element having an open end and a closed end. The open end of the tubular element is adapted to be attached to a fluid conduit carrying pressurized fluid in the system so that the tube fills with the pressurized fluid. The area and length of the tube are such that the fluid within the tube has a resonant condition at a frequency that is the same as at least one frequency of the vibration and noise that is to be reduced or removed in the hydraulic system. A helicopter is also provided having a hydraulic system of pressurized fluid for reducing the transfer of vibrations from the transmission to the airframe including the passive device. Several such passive devices may be applied at selected locations in a hydraulic system for effectively reducing high frequency vibration and noise due to, for example, helicopter transmission gear clashing.

Abstract: A tuning rib is added preferably in the aft cavity of a cored turbine bucket to alter the bucket's natural frequencies. The tuning rib may be a solid rib or a segmented rib and is particularly suited for altering high order frequency modes such as 2T, 4F and 1-3S. As such, detrimental crossings of natural bucket frequencies and gas turbine stimuli can be avoided to thereby improve the reliability of a gas turbine without impacting other features of the bucket that are important to the performance of the gas turbine.

Abstract: The present invention relates to an improved array of flow directing elements for incorporation in turbomachinery. In accordance with the present invention, an array of flow directing elements comprises a plurality of flow directing elements mounted to a rotor disk. The plurality of flow directing elements includes a first set of first flow directing elements whose natural vibration frequency has been modified by having material removed from a leading edge tip region and a second set of second flow directing elements whose natural vibration frequency has been modified by having material removed from a midspan leading edge region. The array may further comprise unmodified flow directing elements arranged with the modified flow directing elements.

Abstract: Helicopter blades each have a piston connected to it. The pistons are movable within a cylinder between innermost and outermost positions. The hydraulic fluid of each cylinder is connected to other cylinders by a hydraulic tube or through a manifold. A drive bar moving synchronously with the blades is connects to the cylinders. As the helicopter moves in flight the force of the wind against a blade causes a piston to move inwardly. This causes fluid to be expelled from the cylinder into the another cylinder by way of the hydraulic tube causing other piston to be moved outwardly. Meanwhile the other piston, because it is moving with the wind, is exerting an opposite effect on the other piston. The result is a tendency for the blades to approach an equilibrium condition with respect to the wind forces to minimize the shocks to the overall system.

Abstract: The present invention relates to an array of flow directing elements for use in turbomachinery. The array comprises a plurality of flow directing elements arranged around a disk in a circular pattern having four quadrants. The flow directing elements in each quadrant are different in mass from the flow directing elements in each adjacent quadrant to reduce the tendency of the array to exhibit tuned absorbed behavior. Further, the number of flow directing elements in each quadrant are different from the number of flow directing elements in each adjacent quadrant to reduce stator vibration in the turbomachinery. Still further, centfrigual pull on the disk is equalized by assembling quadrants with lower flow directing element count from heavier flow directing elements.

Abstract: A damper for reducing vibrations in an integrally bladed turbine disk is provided. The damper includes an annular member and a plurality of fingers. The annular member is configured so that it is coupled to a face of the integrally bladed turbine disk. The plurality of fingers are circumferentially spaced around the annular member. Each of the fingers includes a base portion which is coupled to the annular member and extends radially therefrom. Each of the fingers is tangentially movable relative to the annular member when the turbine disk vibrates in a diametral mode shape such that the plurality of fingers contacts a surface of the turbine disk to absorb vibrations.

Abstract: A turbine disk assembly having an integrally bladed turbine disk and a plurality of captured damper members. The integrally bladed turbine disk includes a plurality of turbine blades that terminate at an integral tip shroud. A damper aperture is formed between each pair of adjacent integral tip shrouds and includes a first slotted portion and a second slotted portion. The first slotted portion is formed concentric to the two adjacent integral tip shrouds, extending circumferentially and axially through the two adjacent integral tip shrouds. The second slotted portion extends radially outwardly between the two adjacent integral tip shrouds. One of the damper members is disposed in the first slotted portion of the an associated damper aperture and frictionally engages at least one surface of each of the two adjacent tip shrouds to dissipate energy when relative motion occurs between the two adjacent integral tip shrouds to dampen vibration.

Abstract: A method and apparatus are used to balance an open blade fan of the kind used with trucks, diesel engine driven generator sets, and the like. An apparatus is used to spin the fans and a vibration sensor senses vibrations and a light beam is used to indicate the location to attach a balancing weight. The fan is spun again and the vibrations measured and additional weights are attached at different specified locations until the measured vibrations are below a predetermined level. The fan includes a plastic body with integral, plastic fan blades which is attached to a central metal hub plate with configured weights attached to matching configured portions of the plastic body. The preferred weights are clips with barbs that pierce the plastic body. The metal hub plates are electrostatically painted to provide a uniformly thick coating with good adhesion.

Abstract: A turbine engine blade damper for damping vibrations of blades in a turbine engine. The blade damper includes an elongate body extending between a forward end and a rearward end opposite the forward end. The body is sized and shaped for receipt within a gap formed between adjacent platforms of the blades so the body frictionally engages the adjacent platforms to dampen vibrations of the blades and to prevent air from passing through the corresponding gap during engine operation. The damper also includes a retainer mounted on at least one of the forward and rearward ends of the body. The retainer is sized and shaped for receipt within a recess formed in at least one of the adjacent blades to hold the body between the blades. The retainer is sized and shaped to prevent air from passing between the blades and the retainer during engine operation.

Abstract: A system for quasi-statically correcting tracking of rotor blades of a helicopter rotor during operation includes a trim tab mounted on each rotor blade and deflectable relative to the rotor blade so as to change a tracking path of the rotor blade, and a rotor track and balance analyzer that includes sensors for acquiring rotor tracking and balance information and is operable to process the rotor tracking and balance information so as to predetermine a new tab position to which the trim tab should be deflected for bringing the tracking path of a mistracking rotor blade into alignment with a reference path. The trim tab is deflected by an actuator mounted to the rotor blade, the actuator having an actuating element coupled with the trim tab and formed of a smart material such that the actuating element deforms proportional to a stimulus applied to the actuating element.

Abstract: A seal for the aft end of a turbine blade and disk assembly of a gas turbine engine to prevent leakage of the cooling air whose main body and cross section are U-shaped that freely fits into a groove formed in the disk lug adjacent the rim of the disk on the aft side thereof. When rotating the center of the base of the U bears against the buttress of the platform of the blade and centrifugal force forces the sides of the U to deform to bear against the walls of the groove.

Abstract: The present invention relates to a blade arrangement with damping elements and to a method of damping vibrations of a blade arrangement. The blade arrangement comprises a rotor and blades arranged on the circumference of the rotor. Damping elements (2, 3) are arranged between the blades and are in contact with the blades due to a centrifugal force, acting in the radial direction, during rotation of the rotor. In this case, at least two damping elements (2, 3) are arranged one behind the other in the circumferential direction of the rotor between adjacent blades, which damping elements (2, 3), during rotation of the rotor, come into contact with one another via a contact surface (6), and of which a first damping element (2) comes into contact with a first friction surface (4) of one of the blades and a second damping element (3) comes into contact with a second friction surface (5) of the other blade.

Abstract: Easy to attach and detach blades for overhead ceiling fans. One version has a fan blade with keyhole slots that fit over flat topped fasteners on a mounting arm. Pulling the blade away from the arm locks the slots to the fasteners. A similar second version has a decorative bottom cover having snappable tapered protrusions which attach through the keyholes and into mateable through-holes in the mounting arm. The third version has a protruding end portion of the blade that fits into a slot in the mounting arm where spring loaded pistons press into grooves in the protrusion end portion of the blade. Latching handles allow users to manually move the pistons. A fourth version has a slot in the blade which fits about a mateable housing in the mounting arm where opposing spring loaded pistons press into interior wall grooves in the slot of the blade.

Abstract: A damper that provides damping for turbine engines to reduce vibrations in the blades, vanes, shrouds, ducting, liner walls and/or other components of the turbine engine. The damper includes an air cavity in a blade, vane, shroud or other engine component and a material covering at least a portion of the air cavity. Vibrations in the turbine engine and its components produce movement of the air inside the air cavity resulting in a corresponding viscous force that dampens the vibrations.

Abstract: A method and apparatus reduces the magnitude of vibratory strain in a turbomachine component that experiences high steady state strain by, in the case of a passive embodiment, coupling a mechanical-to-electromagnetic energy converter to an interior and/or exterior surface of the component, and/or embedding the energy converter within the component, and by, in the case of an active embodiment, coupling a mechanical-to-electromagnetic energy converter to an interior and/or exterior surface of the component.

Abstract: The present invention relates to a blade assembly with damping elements, which comprises a rotor (5) and blades (6) which are installed on the circumference of the rotor and have a blade platform (7), shank (14) and root (8). A damping element (9) is arranged between respectively adjacent blades (6), said damping element (9) being frictionally connected on rotation of the rotor (5), to at least a first region (1, 2) of a first of the respectively adjacent blades (6), and to a second region (3) of a second of the respectively adjacent blades (6). The blade assembly is characterized by the fact that the damping element (9) is configured and arranged between the first and second blades in such a way that the first region (1, 2) and the second region (3) are located at positions which are significantly spaced apart from one another in the radial direction.

Abstract: A system for fluid processing is provided to control shear, point velocity and pressure in either a Newtonian or non-Newtonian fluid, which includes creation of three fields, namely a dynamic microshear field, a dynamic velocity field and a dynamic pressure field, with the fields being created by the injection of energy between 1 KHz and 10 MHz into the fluid. Control is achieved by control of the angle at which mechanical energy is delivered, steering and/or focusing of the energy, control of the amplitude of the energy waveform, of the energy, and control of the frequency of the energy in one embodiment to eliminate standing waves. By controlling the three fields, the system is able to control overall fluid behavior. In one embodiment, energy is injected into a fluid at any angle to the direction of flow assuming the fluid is flowing, with the injected energy providing a predetermined controllable zone of energy in the fluid at the region of energy injection.

Abstract: An aerofoil blade damper comprising an elongate member which is inserted within a core passage of the blade and extends within the blade with the damper retained therein at one end which is closest to the blade root with the remainder of the damper free to move relative to and within the passage; such movement generating friction which dissipates any vibration. The damper comprises a plate insert including at least two discrete substantially oppositely directed contact regions which are arranged, in use, to frictionally engage the passage. The discrete contact regions may be provided by protrusions in the form of contact pads or arms extending from the plate or be provided by the corrugations of the plate. A contact load on the contact regions is provided by the resilience of the damper, an interference fit of the damper and/or centrifugal loading of the damper and contact regions during operation.

Abstract: A rotating blade group 90 for a turbo-machine having an improved device for sealing the gap 110 between the edges 112,114 of adjacent blade platforms 96,104. The gap 110 between adjacent blades 92,100 is sealed by a seal pin 20 its central portion 110 and by a seal plate 58,60 at each of the front 54 and rear 56 portions. The seal plates 58,60 are inserted into corresponding grooves 62,64 formed in the adjacent edges 112,114 of adjoining blades 92,100 and held in place by end plates 40,42. The end of the seal plates 58,60 may be chamfered 78,80 to improve the seal against the end plate 40,42. The seal pin 20 provides the required damping between the blades 92,100 and the seal plates 58,60 provide improved sealing effectiveness.

Abstract: A turbine bucket tip shroud is reinforced by introducing a reinforcing material such as a ceramic-matrix composite as reinforcing rods or bars into the casting of the tip shrouded turbine bucket, to provide resistance to creep deformation. By reducing creep deformation, unlatching of the interlocked tip shrouds is minimized, and bucket overload and vibratory failures are avoided.

Abstract: Porous surfaces on an aerodynamic structure driven with positive and negative pressures are used in an active control system for attenuating shock waves responsible for high-speed impulsive (HSI) noise. The control system includes an array of apertures in the outer skin of the structure providing fluid communication between the exterior flow stream and an interior volume of the structure. A movable diaphragm within the structure pushes air out of and pulls air in through the apertures under the action of a drive mechanism within the structure, thus creating oscillating air jets. The drive mechanism may be actuated by a controller based on information supplied by a sensor in the leading edge of the aerodynamic structure. The array of apertures may be spaced apart along the outer skin of the aerodynamic structure so as to span a distance of about 15% of the chord length. The oscillating airjets may be provided on multiple surfaces of the aerodynamic structure, including the upper and lower surfaces.

Abstract: The invention relates to the use of low-density granular fill with a specific gravity less than 1.5, placed in hollow cavities built into turbomachinery blades, vanes, and shafts. The granular fill provides effective damping at lower frequencies than conventional passive damping treatment due to its low bulk compressional sound speed. Selected materials used for the granular fill treatment are chosen for specific turbomachinery needs, including temperature of operation. Rotation speed is also a factor because it induces on the granular material an apparent hydrostatic pressure associated with the centripetal acceleration, and sound speed in granular materials is a function of pressure raised to the power 1/n. Preferred designs for placement of low-density granular material in appendages and shafts are found using an iterative design tool based on the Direct Global Stiffness Matrix method.

Abstract: A balancing ring for a ceiling fan includes a ring member, a plurality of metal balls, and a ball restraining ring. The ring member has a top side, a bottom side, an inner peripheral wall that confines a central opening, an outer peripheral wall, and an annular groove formed in the top side between the inner and outer peripheral walls. The groove has a groove bottom formed with an annular ball receiving recess. The metal balls are disposed in the ball receiving recess. The ball restraining ring is disposed in the groove above the groove bottom, and is movable inside the groove in at least an axial direction of the central opening between a restricting position, where the metal balls are restricted from moving freely, and a releasing position, where the metal balls are free to move in the ball receiving recess. The ball restraining ring moves in the groove in response to rotating speed of the balancing ring.

Abstract: A plurality of rotatable turbine blades are formed integral with a shroud and platform and a plurality of arcuate plate root portions which are received by circumferential grooves in a rotor and are fastened to the rotor by three pins extending axially through the root portions and the rotor, the shroud and platform portions having a protrusion on one corner to support the trailing edge of one of the blade portions and a notch in the shroud and the platform on the corner opposite the protrusion whereby the protrusions on one group of blades register with the notch on an adjacent group of blades when the groups of blades are disposed in a circular array on the rotor.