Showing papers on "Blade pitch published in 2002"

Wind energy installation

Abstract: The invention relates to a wind energy installation, in particular to a wind energy installation comprising a device for dehumidifying a gaseous medium in an essentially enclosed chamber inside said wind energy installation. The aim of the invention is to minimise the human and logistical resources required to maintain the functional capacity of the device and to simplify the construction of the device, to achieve a virtually maintenance-free operation. To achieve this, the device comprises a first planar element (10) and a cooling device (12) for cooling the first element to a temperature below the ambient temperature.

Telescoping wind turbine blade

Abstract: A wind turbine blade made of a fixed blade section with an integral mounting flange for attachment to a wind turbine hub. A moveable blade section is attached to the fixed blade section and is free to move in a longitudinal direction relative to the fixed blade section. A positioning device controllably positions the moveable blade section to vary the overall length of the blade. This allows the wind turbine's rotor diameter to be adjusted. The rotor diameter can be increased in order to provide high power output in low wind conditions and it can be decreased in order to minimize loads in high wind conditions.

Vertical array wind turbine

Abstract: A wind turbine with an array of rotors arranged at various heights. Each rotor is optimized for the height at which it is located. Optimization of each rotor could include selection of rated power, solidity, tip speed, blade twist, blade taper, or rotor diameter. Each rotor can also be operated in a manner that is optimized for the wind speed it experiences. Optimized operation parameters could include blade pitch angle or rotor speed.

Means for adjusting the rotor blade of a wind power plant rotor

Abstract: Two independent adjusting systems are recommended for each rotor blade (6) for blade angle adjustments of the rotor blades (6) of the rotor of a wind power plant, assuring full redundancy of the blade angle adjustment. By suitable control of the individual adjustment paths of the two adjustments systems, additional advantageous effects can be gained, such as good lubricant distribution and/or even load distribution over time (FIG. 1).

Full-scale wind tunnel test of an individual blade control system for a uh-60 helicopter

Abstract: A full-scale wind tunnel test program was begun to explore the potential of an individual blade control (IBC) system to reduce noise and vibration, and to improve rotor performance of a UH-60 (Black Hawk) helicopter. The first phase of this testing was performed using the U.S. Army/NASA Large Rotor Test Apparatus (LRTA) to operate a full-scale UH-60A rotor in the NASA Ames Research Center 80- by 120-Foot Wind Tunnel. The acquired wind tunnel data set includes measurements of rotor performance, steady and dynamic hub forces and moments, rotor loads, control system loads, and blade vortex interaction (BVI) noise. The LRTA rotor balance was used to assess the level of hub vibration. Both fixed-position and traversing microphones were used to measure the BVI noise. The IBC motions were produced by hydraulic actuators that replaced the normally rigid pitch links of the UH-60 helicopter control system. The actuators were designed by ZF Luftfahrttechnik GmbH to impart up to ±6.0° blade pitch input at the 2/rev frequency and up to ±1.6° at the 7/rev frequency. In this first phase of the test, the IBC system was not tested to its full authority due to limited test time. Nevertheless, the preliminary wind tunnel data obtained demonstrated overall vibration reductions of 70% using approximately 1.0° of 3/rev IBC, and BVI noise reductions of up to 12 dB (75%) using 3.0° of 2/rev IBC. Notation

Helicopter flight around a ship's' superstructure

Abstract: A computationaluid dynamics model of a hovering helicopter main rotor is developed to examine airow in the presence of ship structures and side winds. An illustratio n of the problem is given. The rotor is modelled by modifying the governing N avier±Stokes equations in the region of the disc. The extra terms added to the governing equations apply a downward force to theuid; these forces are independent of theow around the rotor and are equal to the helicopter weight. The helicopter rotor model and the ship model are combined to yield oneow solution, which, due to the severe non-linearities of the problem, cannot be achieved by superpositio n. The resultantow yields valuable data about the induced velocities at the rotor, which ultima tely determine the control pitch and power required to maintain the hover in a given location. Indeed, the interactions between the rotor downwash and ship airow are known to produce unexpected and adverseight dynamic behaviour of the aircraft.

Coupled aircraft rotor system

Abstract: An aircraft with a tilt rotor assembly comprising a craft body, a plurality of rotor blades which are subject to three modes of flight operation, a tilting mast coupling the plurality of rotor blades to the craft body and for selectively moving the plurality of rotor blades between the three modes of flight operation, a hub coupling the plurality of rotor blades to the tilting mast in a manner which transfers torque and thrust while allowing tilting of a rotor thrust vector, a main swashplate for tilting in response to operator input to control the direction of the rotor thrust vector, a plurality of pitch horns, each mechanically coupled to a particular one of the plurality of rotor blades and to the main swashplate, for communicating swashplate input to each of the plurality of rotor blades, a plurality of links coupling the main swashplate to the plurality of pitch horns, wherein each of the plurality of pitch horns is mechanically coupled to a particular one of the plurality of rotor blades by one of the plurality of links in a particular position which yields a delta-3 value which is not optimum, and a feedback swashplate and cooperating feedback links for receiving disk tilting input from the plurality of rotor blades during flight, and for supplying a mechanical input to the main swashplate to compensate for the less than optimum delta-3 coupling between the plurality of pitch horns and the plurality of links. The three modes of flight include: (1) an airplane mode of flight with the plurality of rotor blades in a rotor disk position which is substantially transverse to the craft body; (2) a helicopter mode of flight with the plurality of rotor blades in a rotor disk position substantially parallel to the craft body with direction of flight being controlled by a rotor thrust vector; and (3) a transition mode of flight with the plurality of rotor blades moving between the rotor disk positions associated with the airplane mode of flight and the helicopter mode of flight.

Reducing Low-Pressure Turbine Stage Blade Count Using Vortex Generator Jet Separation Control

Abstract: An experimental investigation has been conducted into the feasibility of increasing blade spacing (pitch) at constant chord in a linear turbine cascade. Vortex generator jets (VGJs) located on the suction surface of each blade in the cascade are employed to maintain attached boundary layers despite the increasing tendency to separate due to the increased uncovered turning. Tests were performed at low Mach numbers and at blade Reynolds numbers between 25,000 and 75,000 (based on axial chord and inlet velocity). The vortex generator jets (30 degree injection angle and 90 degree skew angle) were operated with steady flow with momentum blowing ratios between zero and five, and from two spanwise rows of holes located at 45% and 63% axial chord. In the absence of control, pitch-averaged wake losses increase up to 600% as the blade pitch is increased from its design value to twice the design value. With the application of VGJs, these losses were driven down to or below the losses at the design pitch. The effectiveness of VGJs was found to increase modestly with increasing Reynolds number up to the highest value tested, Re = 75,000. The fluid phenomenon responsible for this remarkable range of effectiveness is clearly more than a simple boundary layer transition effect, as boundary layer trips installed on the same blades without VGJ blowing had no beneficial effect on blade losses. Also, tests conducted at elevated levels of freestream turbulence (4% at the cascade inlet) where the suction surface boundary layer is generally turbulent, showed wake loss reduction comparable to tests conducted at the nominal 1% freestream turbulence. For all configurations, blowing from the upstream row had the greatest wake influence. These findings open the possibility that future LPT designs could take advantage of active separation control using integrated VGJs to reduce the turbine part count and stage weight without significant increase in pressure losses.© 2002 ASME

Periodic disturbance accommodating control for speed regulation of wind turbines

Abstract: Performance of a model-based periodic gain controller is presented using Disturbance Accommodating Control (DAC) techniques to estimate fluctuating wind disturbances. Operation is restricted to speed regulation using Independent Blade pitch Control (IBC) and by measuring only rotor angle and speed. The modeled turbine is a free-yaw, two-bladed, teetered rotor machine with simple blade and tower flexibility — 6 discrete degrees of freedom. A comparison is made to a time-invariant DAC controller, constructed by various approaches. Results indicate that the two controllers perform nearly identically, despite the inherent periodic dynamics in the system. The best time-invariant state estimator model was designed by freezing the periodic plant at a specified rotor azimuth position.Copyright © 2001 by The American Institute of Aeronautics and Astronautics Inc. and ASME

Lubrication of a pitch angle adjusting device of a rotor blade of a windmill

Abstract: The invention relates to a device for rotating the shaft of a rotor blade of a wind energy plant relative to a hub of said wind energy plant. The inventive device comprises a bearing between the structural components and a gearwheel drive for actuating the rotation and adjusting the pitch of the rotor blade. According to the invention, a gearwheel of the drive and the bearing are disposed in the volume of a lubricant chamber.

Method and apparatus for bucket natural frequency tuning

Abstract: A method of modifying a rotor blade, and a rotor blade are provided. The rotor blade is for a steam turbine and it is modified to facilitate altering a natural vibratory frequency of the rotor blade, the rotor blade includes a leading edge, a trailing edge, a first sidewall, and a second sidewall, wherein the first and second sidewalls are connected axially at the leading and trailing edges, and the sidewalls extending radially between a rotor blade root to a rotor blade tip. The method includes determining a vibratory resonance condition of the rotor blade and forming a blade extension between the rotor blade root and the rotor blade tip that alters the determined resonance condition.

Propellers and propeller related vehicles

Abstract: A propeller related vehicle in accordance with one embodiment of the present invention is described as a helicopter having an airframe housing a motor mechanism for powering a main propeller attached to a main drive shaft that extends vertically through the airframe and for powering a tail rotor. The helicopter further includes a horizontal stabilizing mechanism attached between the main propeller and the main drive shaft, which permits the main propeller to freely pivot about the main drive shaft independently from the airframe. As such when the main propeller is rotating and the main propeller begins to pitch, the rotating main propeller has a centrifugal force created by the rotation thereof and will tend to pivot about the horizontal stabilizing mechanism in a manner that offsets the pitch such that the helicopter remains in a substantially horizontal position. In addition various main propeller configurations may be employed that provide additional self-stabilization.

Using dual propeller s as gyroscopes for tilt -prop hover control

Abstract: The concepts and preliminary experimental verification are presented for simple, small footprint VTOL aircraft that use just two conventional airplane propellers for lift, stability, and control in hover. By utili zing the propellers’ gyroscopic properties no helicopter -type cyclic controls are required, nor are any other reactive devices, such as vanes in the propeller slipstreams or an exhaust nozzle in the tail. In one method, by mounting the prop -motors on gimba ls and applying to them opposing lateral moments, absolute pitch control of the aircraft (in a side -by -side propeller arrangement) is obtained by their ensuing gyroscopic precession in the longitudinal direction. In the other, forced lateral precession of the propellers creates gyroscopic pitching moments and a pitch component of the propeller torques that assist or supplant thrust vectoring for pitch control, manifested in the fixed and variable oblique tilting techniques, which are conducive to the use of coupled -drive systems. Indefinite -duration stationary hovers and quick maneuvering responses were achieved with an untethered, radio -controlled electric test aircraft employing the fixed oblique tilting method. Variable oblique tilting has the added b enefit of potentially providing both inherent roll control and inherent transition means, and may negate the pitch -up tendency of propellers when flying longitudinally in hover.

Passive speed and power regulation of a wind turbine

Abstract: A wind turbine has its blades (1) arranged so that they can pitch towards stall against the action of a spring (15) or other resilient device. The centrifugal loading on the blades (1) acts against the spring (15) in a direction to shed power by pitching the blades (1) towards the stall. The torque loading provided by the generator or other power conversion device acts to pitch the blades (1) in the opposite direction, so as to reduce the amount of load shedding whenever the power is being extracted from the wind turbine.

Rotor blade of a wind power installation, comprising a warning light

Abstract: Wind power installations with rotor blades of different kinds are already known. It is likewise known that in certain situations the wind power installation has to be provided with a hazard beacon in order to warn air traffic in the area of the wind power installation in due time of the existence of the wind power installation. It is also known for the above-mentioned purpose to provide the rotor blades with mostly red warning paints so as to avoid the collision of an aircraft, especially a military aircraft, with a wind power installation or the rotor thereof. The aim of the invention is to provide a more reliable lighting of the rotor blade tips which can, when damaged, be repaired more easily and quickly. The rotor blade of a wind power installation with a rotor blade connection to a hub of the wind power installation and a rotor blade tip on the end of the rotor blade opposite said rotor blade connection is characterized in that at least one fiber optic cable is laid from the rotor blade connection to the rotor blade tip.

Aerodynamic performances of propellers with parametric considerations on the optimal design

Abstract: In this paper two numerical procedures are presented: the first algorithm allows for the determination of the geometric characteristics of the maximum efficiency propeller for a given operative condition and profile distribution along the blade; the output of this numerical procedure is the chord distribution and twist angle of the blade, together with its efficiency and its torque and thrust coefficients for the prescribed operative condition. The aerodynamic characteristics of the optimum propeller when operating in a condition different from the design one are obtained by a second algorithm that allows for the evaluation of the efficiency, the thrust and torque coefficients of a propeller of known geometry, when the blade pitch and operative condition are varied. In the paper the formulation used for deriving the geometry of the optimum propeller and determining its performances when operating off-design is described in detail. The results obtained from the proposed propeller model have been validated by comparison with experimental data.

Device for adjustment of rotor blades of the rotor in a wind power system

Abstract: Between the blade (6) and the rotor hub a tubular section (8) is fitted. At the upper end the section is linked to the blade by a roller bearing (18) the inner ring (19) of which engages with a motor (21) driven pinion (20). This arrangement is duplicated and the motors are controlled to adjust the blade angle in unison. The power for operating the motors can be electrical, hydraulic or mechanical ( using the rotational energy of the rotor.

Pneumatic driven propeller related vehicles

Abstract: A propeller related vehicle in accordance with one embodiment of the present invention is described as a helicopter having an airframe housing a pneumatic motor mechanism for powering a main propeller attached to a main drive shaft. The helicopter further includes a horizontal stabilizing means attached between the main propeller and the main drive shaft, which permits the main propeller to freely pivot about the main drive shaft independently from the airframe. As such when the main propeller is rotating and the main propeller begins to pitch, the rotating main propeller has a centrifugal force created by the rotation thereof and will tend to pivot about the horizontal stabilizing means in a manner that offsets the pitch such that the helicopter remains in a substantially horizontal position.

Optimum pitch control for variable-pitch vertical-axis wind turbines by a single stage model on the momentum theory

Abstract: We propose a new approach to realize the optimum control of the pitch angles of the blades on a variable-pitch straight-blade type of vertical-axis wind turbine. After deriving the power coefficient and the tip speed ratio of the turbine by merging the single-stage momentum theory and the blade element analysis, we can solve the stationary problems by using the Calculus of Variations and obtain the optimum pitch-angle control law on a tip speed ratio and calculate the power coefficient.

Method and system for active noise control of tiltrotor aircraft

Abstract: Methods and systems for reducing noise generated by rotating blades of a tiltrotor aircraft A rotor-blade pitch angle associated with the tiltrotor aircraft can be controlled utilizing a swashplate connected to rotating blades of the tiltrotor aircraft One or more Higher Harmonic Control (HHC) signals can be transmitted and input to a swashplate control actuator associated with the swashplate A particular blade pitch oscillation (eg, four cycles per revolution) is thereafter produced in a rotating frame of reference associated with the rotating blades in response to input of an HHC signal to the swashplate control actuator associated with the swashplate to thereby reduce noise associated with the rotating blades of the tiltrotor aircraft The HHC signal can be transmitted and input to the swashplate control actuator to reduce noise of the tiltrotor aircraft in response to a user input utilizing an open-loop configuration

Wind power plant stabilization

Abstract: The invention concerns wind newer plant stabilization. An embodiment of a wind power plant includes a rotor to rotate about a rotor axis, a rotor blade coupled with the rotor, the rotor blade including a torque adjustment, and a stabilizing system to stabilize the rotor in a position, the stabilizing system including a control to adjust the torque of the rotor blade to counteract changes in a rotational position of the rotor.

VTOL aircraft propulsion systems and forward flight thrust vectoring

Abstract: This invention describes vertical take off and landing (VTOL) propulsion systems that develop a forward flow of air through the air intake ducts during vertical takeoff and landing. This forward air flow in the air intake ducts is developed by a internal duct system, reversing the rotation of the fan, or altering the blade pitch of a variable pitch fan. This invention describes thrust vectoring systems for controlling aircraft direction, attitude, pitch, roll, yaw and rotation during VTOL and forward flight. Rotational nozzles are described to function in a independent but coordinated manner to control the aircraft during VTOL and forward flight. A thrust vectoring variable throat converging diverging exhaust duct nozzle is described. A movable radar absorbing or reflecting grid may be located in the air intake duct. The radar grid is movable to increase aircraft speed and engine efficiency when the aircraft is not operating in a radar threat situation. The described VTOL propulsion systems and thrust vectoring methods are applied to a aircraft with a internal combustion engine.

Wind turbine in parked position

Abstract: The invention relates to a method for operating a wind power plant with a rotor and with at least two rotor blades rotatable about a common rotor axis in a rotor blade plane, whereof each can be swivelled about a swivel axis which is roughly parallel to its longitudinal axis approximately perpendicular to the rotor axis, in which the setting or pitch angels of the rotor blades are set with respect to the rotor blade plane as a function of the operating and in particular wind conditions, in which the pitch angels of at least two rotor blades in a parking position of the rotor, in which rotor rotation about the rotor axis is decelerated, are set to different values.

Method for in situ construction of a wind power plant

Abstract: The present invention concerns a process for mounting rotor blades to a rotor hub of a wind power installation in situ. In order to avoid high torques in the mechanical train of the wind power installation in the operation of mounting the rotor blades, the process according to the invention includes the following steps: mounting a weight to at least one flange of the rotor hub; mounting the rotor blade in the installation situation; rotating the rotor hub into a predeterminable position; and exchanging the weight arranged on the flange of the rotor hub for a rotor blade by removing the weight and then mounting the rotor blade to the rotor hub.

Helicopter individual blade control system

Abstract: In an individual rotor blade control device for a helicopter main rotor with a rotor shaft that can be driven by a main drive, with an even number of rotor blades that are arranged on the periphery of a rotor hub, with primary control mechanisms for collective and sinusoidal, cyclic rotor blade adjustment, which include a transfer element for the control movements from a non-rotating system to a rotating system and with actuators that are individually allocated to the rotor blades, wherein the actuator control movement is superimposed onto the control movement of the primary control mechanisms and each actuator is equipped with a safety device in order to bring the actuator into its final position and keep it there, if necessary, it is suggested that the setting angle change of one half of the rotor blades have an opposed direction due to the securing of the actuators in their final positions, like the setting angle change of the other half of rotor blades, and that the rotor blades of each half be distributed on the periphery in such a way that no pitching moments that could affect the rotor are generated.

Total Unsteadiness Downstream of an Axial Flow Fan With Variable Pitch Blades

Abstract: Variable pitch axial flow fans are widely used in industrial applications to satisfy variable operating conditions. The change of the blade pitch leads to a different rotor geometry and has a major influence on the unsteady operation of the machine. In this work, an experimental research on an axial flow fan with variable pitch blades has been carried out. First of all, the fan performance curves has been obtained. Then the flow field has been measured at ten radial locations both at the inlet and exit rotor plane using hot wire anemometry. Velocity components and total unsteadiness were determined and analyzed in order to characterize the influence of pitch blade and operating conditions on the flow structure

Twin-rudder system for large ship

Abstract: A high-lift twin rudder system, wherein a pair of high-lift rudders (1) and (2) having top end plates (6) and (7) at the top end part of rubber blades (4) and (5) and bottom end plates (8) and (9) at the bottom end part thereof are disposed at the rear of a pusher propeller (3), fins (10) and (11) having specific chord lengths from generally leading edge parts rearward are provided on the inboard sides of the rudder blades (4) and (5) at approximately the same level as the axis of the pusher propeller (3), the fin (10) of one rudder blade (4) opposed to the board side where the pusher propeller blades are rotated upward has an attitude forming such an angle of attach at which the ratio of a thrust in forward direction caused by the wake flow behind the pusher propeller having an upward component of the flow to a drag becomes maximum and the fin (11) of the other rudder blade (5) opposed to the board side where the pusher propeller blades are rotated downward has an attitude forming such an angle of attach at which the ratio of a thrust in forward direction caused by the wake flow behind the pusher propeller having a downward component of the flow to a drag becomes maximum, and the chord lengths of the rudder blades (4) and (5) are formed to be 60 to 45% of the diameter of the pusher propeller.

Pitch alignment adjusting method for wind mill

Abstract: PROBLEM TO BE SOLVED: To provide a pitch alignment adjusting method for a wind mill capable of simply adjusting the pitch alignment without causing a high cost and realizing a small size and a light weight or an enhancement of durability of a sub system and a reduction of a facility/business cost. SOLUTION: While a rotor 4 is rotated at a constant speed in the state that a pitch angle of an optional one blade 6c among a plurality of blades 6a, 6b, 6c is fixed, pitch angles of remaining blades 6a, 6b are changed by the corresponding actuators. The vibration state of a nacelle at the respective pitch angles is measured and the optimum combination of pitch angles of the plurality of blades 6a, 6b, 6c is determined based on the measurement result of the vibration state. The pitch alignment is adjusted through the corresponding actuators so as to meet the pitch angles of the determined combination. COPYRIGHT: (C)2003,JPO

Progressive shear assembly for outboard motors and out drives

Abstract: A progressive shear assembly which is suitably adapted for connecting a marine propeller to a propeller drive shaft in such a manner that a selected resilience and torsional resistance of the propeller with respect to the drive shaft is achieved An adaptor shaft provided on the propeller drive shaft drivingly engages the propeller through multiple sets of shear rods each having a selected composition and resilience In the event that the rotating propeller inadvertently strikes an underwater object, the shear rods absorb the torque shock Accordingly, the shear rods tend to deform and shear to prevent damage to the propeller and propeller drive train components, and can be easily and inexpensively replaced