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Showing papers on "Rotor (electric) published in 1981"


Proceedings ArticleDOI
01 Nov 1981
TL;DR: In this paper, a two dimensional section of a helicopter main rotor blade was tested in an acoustic wind tunnel at close to full-scale Reynolds numbers to obtain boundary layer data and acoustic data for use in developing an acoustic scaling law and testing a first principles trailing edge noise theory.
Abstract: A two dimensional section of a helicopter main rotor blade was tested in an acoustic wind tunnel at close to full-scale Reynolds numbers to obtain boundary layer data and acoustic data for use in developing an acoustic scaling law and testing a first principles trailing edge noise theory. Results were extended to the rotating frame coordinate system to develop a helicopter rotor trailing edge noise prediction. Comparisons of the calculated noise levels with helicopter flyover spectra demonstrate that trailing edge noise contributes significantly to the total helicopter noise spectrum at high frequencies. This noise mechanism is expected to control the minimum rotor noise. In the case of noise radiation from a local blade segment, the acoustic directivity pattern is predicted by the first principles trailing edge noise theory. Acoustic spectra are predicted by a scaling law which includes Mach number, boundary layer thickness and observer position. Spectrum shape and sound pressure level are also predicted by the first principles theory but the analysis does not predict the Strouhal value identifying the spectrum peak.

174 citations


Patent
29 Apr 1981
TL;DR: In this article, a variable threshold circuit combines the signal proportional to the rotational speed of the rotor and the determined field coil excitation current to produce an output signal level indicative of the detection of a voltage ripple in excess of the combined signal level.
Abstract: Detector (28) monitoring the voltage ripple in the rectified electrical output signal of an alternator (22) in a multiphase alternator battery charging system. A circuit monitors the undulating alternator output signal and produces a signal level in response. To correct the detector operation for various magnetic phenomena present in the alternator, a first circuit measures the rotational speed of the rotor and produces a proportional signal. A second circuit determines the excitation current supplied to the field coil. The measurement and determination are separately weighted and combined to form a corrected comparison threshold value. A variable threshold circuit combines the signal proportional to the rotational speed of the rotor and the determined field coil excitation current to produce a combined signal level. Comparison means compare the signal level from the monitored alternator output signal with the combined signal level and produce an output signal level indicative of the detection of a voltage ripple in excess of the combined signal level. The output signal is corrected for the effects of significant alternator performance characteristics.

144 citations


Patent
Howard R. Kutcher1
27 Jul 1981
TL;DR: In this article, a Darrieus-type vertical axis wind turbine is described, which includes a vertically extending rotor tube mounted on a support structure with two or three rotor blades of troposkein configuration on the rotor tube for rotating the tube in response to wind energy.
Abstract: A Darrieus-type vertical axis wind turbine is disclosed which includes a vertically extending rotor tube mounted on a support structure with two or three rotor blades of troposkein configuration on the rotor tube for rotating the tube in response to wind energy and thereby drive a generator to produce electrical power. The turbine includes an erection hinge which permits assembly of the rotor tube and blades at close to ground level followed by upward hinging of the rotor assembly to a vertical position. It also includes a system for automatically lubricating the top bearing upon erection and a system for visually tensioning the guy cables.

122 citations


Patent
20 Nov 1981
TL;DR: A rotor unit for a centrifugal analyzer comprises a rotatably driven circular rotor base; and a rotor head comprising a plurality of insert elements each having at least one chamber sample for the reception of a sample liquid.
Abstract: A rotor unit for a centrifugal analyzer comprises a rotatably driven circular rotor base; and a rotor head comprising a plurality of insert elements each having at least one chamber sample for the reception of a sample liquid, at least one measuring chamber radially outwardly from the associated sample chamber for the measurement of characteristic parameters for the detection of components of the sample, at least one liquid channel connecting the sample chamber with the measuring chamber and each insert element is releasably mounted on the rotor base at any one of a plurality of different selectable angular positions wherein the insert element is positionally stable when the rotor base is rotating.

107 citations


Journal ArticleDOI
01 Sep 1981
TL;DR: In this paper, the authors investigated the wind-rotor/generator dynamics for a number of control policies, and it was shown that the system response is a function of wind speed.
Abstract: Wind energy is usually converted into electrical energy through a wind rotor driving a generator. It is well known that maximum conversion efficiency occurs when the wind rotor is loaded in such a way that its rotational speed is allowed to fluctuate in sympathy with wind-speed variations. In the paper, the wind-rotor/generator dynamics are investigated for a number of control policies, and it is shown that the system response is a function of wind speed. Owing to this relationship, control strategies based on static optimum matching premises are unlikely to be optimal under continuously changing conditions. To prove this hypothesis, the aerogenerator dynamics were simulated on an analogue computer, and, for a given recorded windspeed sample, the energy delivered was measured for a number of control strategies. The results indicate that, for the wind sample used and aerogenerator simulated, sophisticated control policies do not necessarily result in maximum energy yield. An attempt is made to interpret this paradox in terms system dynamics

102 citations


Ion Paraschivoiu1
01 May 1981
TL;DR: In this paper, an analytical model is proposed for calculating the rotor performance and aerodynamic blade forces for Darrieus wind turbines with curved blades, which uses a multiple-streamtube model, divided into two parts: one modeling the upstream half-cycle of the rotor and the other, the downstream half cycle.
Abstract: An analytical model is proposed for calculating the rotor performance and aerodynamic blade forces for Darrieus wind turbines with curved blades. The method of analysis uses a multiple-streamtube model, divided into two parts: one modeling the upstream half-cycle of the rotor and the other, the downstream half-cycle. The upwind and downwind components of the induced velocities at each level of the rotor were obtained using the principle of two actuator disks in tandem. Variation of the induced velocities in the two parts of the rotor produces larger forces in the upstream zone and smaller forces in the downstream zone. Comparisons of the overall rotor performance with previous methods and field test data show the important improvement obtained with the present model. The calculations were made using the computer code CARDAA developed at IREQ. The double-multiple streamtube model presented has two major advantages: it requires a much shorter computer time than the three-dimensional vortex model and is more accurate than multiple-streamtube model in predicting the aerodynamic blade loads.

87 citations


Journal ArticleDOI
TL;DR: In this article, a simple approximate solution to compressible fluid flow problems is used to arrive at useful design equations for high-speed spinning on cylindrical air bearings for NMR studies of solids.
Abstract: Simple approximate solutions to compressible fluid flow problems are used to arrive at useful design equations for high‐speed spinning on cylindrical air bearings for NMR studies of solids. The optimum radial clearance is shown to depend on the 1/3 power of the rotor diameter, and is 0.027 mm for a 12‐mm rotor, with a surface speed of one half the speed of sound, c. The required air bearing hole diameter is about 0.3 mm with a square root dependence on the rotor diameter. A few general comments are made concerning turbine design, and a simple combination impulse‐reaction type is described which offers some improvement in drive efficiency. Drive air flow is shown to depend approximately on the square root of the rotor volume for a surface speed 0.5 c. Relevant data for a number of high strength materials including hard ceramics are tabulated, and limiting speeds are calculated. The design equations are verified for 8 and 12 mm rotors made from Al2O3 with wall thicknesses equal to 6% of the diameter.

86 citations


Patent
20 Mar 1981
TL;DR: In this paper, an electrical machine which can be run as a synchronous generator or as a pump is disclosed. The machine is a true hybrid of a turbine and synchronous generators in that the turbine blades are designed to carry magnetic flux.
Abstract: An electrical machine which can be run as a synchronous generator or as a pump is disclosed. The machine is a true hybrid of a turbine and synchronous generator in that the turbine blades are designed to carry magnetic flux. To that end the blades are made of ferromagnetic material, have pole tips and may be laminated. The blades are preferably of aerofoil section and must be much thicker than conventional turbine blades so as to be capable of carrying the substantial magnetic flux. Field coils provided at the roots of the blades or around the hub of the rotor carrying the blades generate magnetic flux which is carried up through the blades across air gaps to a stator, which may be a conventional synchronous generator stator, and back through the air gaps and blades. The machine is relatively simple and rugged and has fewer parts than conventional turbine generator combinations particularly in that only a single rotor, rather than two, is necessary.

83 citations


Patent
20 Feb 1981
TL;DR: In this paper, the rotational speed of an electronically controlled power tool in both the forward and reverse direction is controlled by a tachogenerator, which is adapted to sense a change in the state of the reversing switch and remove power to the motor until it coasts down to a relatively slow speed or to zero before reapplying power in the opposite direction.
Abstract: A method and apparatus for controlling the rotational speed of an electronically controlled power tool in both the forward and reverse direction When the reversing switch is placed in the reverse direction, the electronic speed control circuit automatically limits the speed of the motor to a predetermined maximum value The speed control circuit also is adapted to sense a change in the state of the reversing switch and remove power to the motor until it coasts down to a relatively slow speed or to zero before reapplying power in the opposite direction The speed control circuit monitors the rotational speed of the motor by means of a tachogenerator comprising a ring magnet mounted on the rearward end of the rotor shaft of the motor outboard of the commutator-end bearings and a Hall effect device mounted to the peripheral flange of a carrier which encircles the ring magnet so that the ring magnet and Hall effect device are separated by a small radially extending gap

75 citations


Patent
11 Sep 1981
TL;DR: In this paper, the annular space between the motor shaft and a driveshaft provides a passage wherein fluid is distributed to the motor and the transmission under pressure, and the fluid returns to a common sump by gravity from the motors and transmission.
Abstract: The electric motor and transmission that apply power to the drive wheels of a vehicle are supplied with hydraulic fluid to lubricate the transmission and to cool the motor by a common fluidic circuit. The annular space between the motor shaft and a driveshaft provides a passage wherein fluid is distributed to the motor and the transmission under pressure. The rotor of the motor has axial passages through which the fluid flows from a radial passage connecting the annular space with the passages. At each axial end of the rotor fluid exiting the rotor, is thrown outward onto the inner surfaces of the stator windings. The fluid returns to a common sump by gravity from the motor and transmission.

74 citations


PatentDOI
TL;DR: In this paper, a vibration diagnosis method and apparatus for rotary machines adapted for measuring the vibration of rotor shaft of a rotary machine, extracting the vibration component synchronous with the revolution of the rotor shaft from the measured vibration data, comparing the amplitude of the extracted vibration component with the amplitude in the overall vibration, analyzing the causes of the synchronous vibration component when the result of the comparison meets a predetermined reference, judging, in accordance with the results of the analysis, whether the vibration due to mass unbalance is attributable to an abrupt generation of massunbalance or to a
Abstract: A vibration diagnosis method and apparatus for rotary machines adapted for measuring the vibration of rotor shaft of a rotary machine, extracting the vibration component synchronous with the revolution of the rotor shaft from the measured vibration data, comparing the amplitude of the extracted vibration component with the amplitude of the overall vibration, analyzing the causes of the synchronous vibration component when the result of the comparison meets a predetermined reference, judging, in accordance with the result of the analysis, whether the vibration due to mass unbalance is attributable to an abrupt generation of mass unbalance or to a thermal bow of the rotor shaft, and displaying the result of the judgment. The analysis of the vibration component is made in real time or making use of data stored in the past.

Patent
18 Mar 1981
TL;DR: A subcutaneous valve for the treatment of hydrocephalus adapted to be inserted between a ventricular catheter and a distal catheter is described in this article, where the rotor is a disk in the form of a cut-out circular sector having a peripheral surface and two radial end surfaces.
Abstract: A subcutaneous valve is provided for the treatment of hydrocephalus adapted to be inserted between a ventricular catheter and a distal catheter. The valve comprises a body enclosing a chamber having formed through its cylindrical wall an inlet and outlet passage for cephalorachidian fluid. A rotor is journaled in the chamber for rotation about the chamber axis. A spring blade, fixed to the rotor extends arcuately along a cylindrical wall, bearing deflectably outwardly against a valve member and slides thereon to bias the member against a valve seat with a force depending on the angular position of the rotor and the chamber. The rotor is a disk in the form of a cut-out circular sector having a peripheral surface and two radial end surfaces. A stop means extends from a bottom wall of the chamber between the radial end surfaces of the rotor. The foregoing valve avoids the siphon effect when a patient moves between vertical and horizontal positions and is easily calibrated at any desired closing pressure for implantation.

Patent
29 Dec 1981
TL;DR: In this paper, a magnetic disc storage driving mechanism is provided for a DC brushless driving motor having a stator and a rotor, a contaminant free space without air intake provision for containing storage disks, bearings mounting the rotor for rotation and for driving a hub which receives at least one rigid storage disk within the contaminant-free space.
Abstract: A magnetic disc storage driving mechanism is provided comprising a DC brushless driving motor having a stator and a rotor, a contaminant-free space without air intake provision for containing storage disks, bearings mounting the rotor for rotation and for driving a hub which receives at least one rigid storage disk within the contaminant-free space, and labyrinth seals arranged between the drive parts of the motor and the contaminant-free space containing the storage disk.

Patent
Imdad Imam1
27 Mar 1981
TL;DR: In this paper, a method for detecting cracks in the rotor of a turbine-generator while the turbine was on-line operating under normal conditions is presented, which is demonstrated to be sufficiently sensitive to detect cracks having a depth on the order of less than one percent the diameter of the rotor.
Abstract: A method is disclosed for detecting incipient cracks in the rotor of a turbine-generator while the turbine-generator is on-line operating under normal conditions. Vibration signature analysis is performed on a set of difference signals produced by superposing and subtracting corresponding enhanced background and foreground vibration signals. Each enhanced vibration signal is created by superposing and summing an integral number of vibration signal segments, each segment corresponding to one revolution of the rotor. An incipient crack is manifested principally by the appearance and increase in relative amplitude of signal harmonics at twice the rotational speed of the rotor. The method of the invention is sufficiently sensitive to detect cracks having a depth on the order of less than one-percent the diameter of the rotor.


Patent
31 Aug 1981
TL;DR: In this paper, a motor control system wherein the motor windings are energized by sinusoidal excitation currents synthesized from prerecorded sine values is presented, and the phase of the winding excitation is additionally controllable as a function of speed or some other adequate system parameter.
Abstract: A motor control system wherein the motor windings are energized by sinusoidal excitation currents synthesized from prerecorded sine values. The frequency of the winding excitation currents is synchronous with the rotor movement and the phase is a function of the rotor position with respect to the stator. The phase of the winding excitation is additionally controllable as a function of speed or some other adequate system parameter. It has further been found that the total operational speed range of the system is substantially increased by further adjusting and controlling the phase of the excitation currents as a function of the desired speed.

PatentDOI
TL;DR: In this article, a method and apparatus for diagnosing a vibration in a rotor of a rotary machine is presented, including detecting the number of rotations and the vibration in the rotor when the rotor is rotating, determining whether the vibration component is normal or abnormal, calculating an abnormal vibration component through a vector operation by using the detected vibration component and a previously determined rotor vibration component.
Abstract: A method and apparatus for diagnosing a vibration in a rotor of the rotary machine including detecting the number of rotations and the vibration in the rotor when the rotor is rotating, extracting a vibration component synchronized with the number of rotations, determining whether the vibration component is normal or abnormal, calculating an abnormal vibration component through a vector operation by using the detected vibration component and a previously determined rotor vibration component in a normal state of the rotor, when the detected vibration component is judged to be abnormal, normalizing a vibration pattern of the abnormal vibration component, and determining an unbalance originating position in the rotor, which generates the abnormal vibration, by using a comparison of the normalized abnormal vibration pattern with a normalized vibration pattern of a previously determined unbalanced vibration.

Patent
06 Apr 1981
TL;DR: In this article, a wind turbine rotor speed control for ensuring a constant rotational speed within tight tolerances includes a self-sufficient rotor (16) incorporating aerodynamic and mechanical devices to provide the control.
Abstract: A wind turbine rotor speed control for ensuring a constant rotational speed within tight tolerances includes a self-sufficient rotor (16) incorporating aerodynamic and mechanical devices to provide the control. There is a fixed turbine blade (26) adapted to be mounted on a shaft (14) for rotation therewith, the fixed blade (26) having pivotal blade tips (28) at its respective ends. The pitch control of the blade tips regulates the rotor speed. Aerodynamic tabs (180) are pivotally secured adjacent each of the ends of the respective trailing edges (34, 36) of the fixed blade. The relative wind acts on each tab which is connected to a series of links (188-168) and pitch cams (86) to regulate the pitch of the blade tips from a feathered position (210), to a cut-in position (212), to a rated wind position, and vice-versa. There are torque cams (60) actuated by torsional strain on the shaft bearing which is connected to the shaft (14) and to the pitch cams (86) by a series of links ( 52, 54) so that as the wind approaches its rated velocity value the pitch cams (86) become ineffective (228) and the torque cams (60) take over the speed control. There are also overspeed centrifugal devices (80) connected to the pitch cams (86) to cause the blade tips (28) to feather in emergency overspeed conditions so as to stop the rotor (16).

Journal ArticleDOI
TL;DR: In this article, a method for the calculation of the electromagnetic torque in electric machines is proposed based on an analytical field calculation in the air-gap combined with finite element field calculations in the saturated rotor and stator iron.
Abstract: In many engineering applications the calculation of forces and torques is subject of great importance [7] , [8]. A method for the calculation of the electromagnetic torque in electric machines is proposed in the paper. This method is based on an analytical field calculation in the air-gap combined with finite element field calculations in the saturated rotor and stator iron. The results of field calculation obtained using such a method are more precise than those calculated by the classical finite element method; thus the accuracy of the calculated torque will be better. An application for the case of synchronous machine is given at the end of the paper.

Patent
11 May 1981
TL;DR: In this paper, a Magnus effect windmill for generating electrical power is described, with three elongated barrels arranged in a vertical plane and extending symmetrically radially outwardly from the nacelle.
Abstract: A Magnus effect windmill for generating electrical power is disclosed. A large nacelle-hub mounted pivotally (in Azimuth) atop a support tower carries, in the example disclosed, three elongated barrels arranged in a vertical plane and extending symmetrically radially outwardly from the nacelle. The system provides spin energy to the barrels by internal mechanical coupling in the proper sense to cause, in reaction to an incident wind, a rotational torque of a predetermined sense on the hub. The rotating hub carries a set of power take-off rollers which ride on a stationary circular track in the nacelle. Shafts carry the power, given to the rollers by the wind driven hub, to a central collector or accumulator gear assembly whose output is divided to drive the spin mechanism for the Magnus barrels and the main electric generator. A planetary gear assembly is interposed between the collector gears and the spin mechanism functioning as a differential which is also connected to an auxiliary electric motor whereby power to the spin mechanism may selectively be provided by the motor. Generally, the motor provides initial spin to the barrels for start-up after which the motor is braked and the spin mechanism is driven as though by a fixed ratio coupling from the rotor hub. During high wind or other unusual conditions, the auxiliary motor may be unbraked and excess spin power may be used to operate the motor as a generator of additional electrical output. Interposed between the collector gears of the rotating hub and the main electric generator is a novel variable speed drive-fly wheel system which is driven by the variable speed of the wind driven rotor and which, in turn, drives the main electric generator at constant angular speed. Reference is made to the complete specification for disclosure of other novel aspects of the system such as, for example, the aerodynamic and structural aspects of the novel Magnus barrels as well as novel gearing and other power coupling combination apparatus of the invention. A reading of the complete specification is recommended for a full understanding of the principles and features of the disclosed system.

Patent
17 Jun 1981
TL;DR: Disclosed as discussed by the authors is a device intended primarily for home use for both vacuuming and scrubbing facial skin surfaces to remove oils and debris from the skin, which is adapted for attachment to a conventional water outlet and comprises a Venturi tube to which is attached a housing overlying the tube.
Abstract: Disclosed is a device, intended primarily for home use, for both vacuuming and scrubbing facial skin surfaces to remove oils and debris from the skin. The device is adapted for attachment to a conventional water outlet and comprises a Venturi tube to which is attached a housing overlying the throat suction aperture of the tube. The housing accommodates a turbine rotor which is rotated by the flow of water through the Venturi throat and the rotor drives a remote facial brush. Coaxial with the rotor is a vacuum controlling rotor which may deliver continuous or pulsating vacuum. When producing pulsating vacuum, the rotor periodically interrupts or pulses the vacuum produced in the housing which, via a flexible tube, is utilized by a remote vacuum head applied by the user to his facial surfaces.

01 Nov 1981
TL;DR: In this paper, a technique for controlling a doubly fed induction generator driven by a windmill, or other form of variable-speed prime mover, to provide power generation into the national grid system is described.
Abstract: The paper describes a technique for controlling a doubly fed induction generator driven by a windmill, or other form of variable-speed prime mover, to provide power generation into the national grid system. The secondary circuit of the generator is supplied at a variable frequency from a current source inverter which for test purposes is rated to allow energy recovery, from a simulated windmill, from maximum speed to standstill. To overcome the stability problems normally associated with doubly fed machines a novel signal generator, which is locked in phase with the rotor EMF, controls the secondary power to provide operation over a wide range of subsynchronous and supersynchronous speeds. Consideration of power flow enables the VA rating of the secondary power source to be determined as a function of the gear ratio and online operating range of the system. A simple current source model is used to predict performance which is compared with experimental results. The results indicate a viable system, and suggestions for further work are proposed

Patent
Eike Richter1
12 Jan 1981
TL;DR: In this paper, the output regulation of a permanent magnet excited disk-type synchronous machine with rotor disks in multipolar configuration is achieved by controlled alignment of stator windings.
Abstract: Output regulation of a permanent magnet excited disk-type synchronous machine having permanent magnets attached to rotor disks in multipolar configuration is achieved by controlled alignment of stator windings. Rotor disks support permanent magnets oriented to direct flux axially through the machine, and multiple stator disks having distributed multi-phase windings have means to rotate one of the stator disks to cause misalignment of windings on adjacent disks having the same phase. By controlling the degree of phase misalignment, output voltage of a generator or power factor of a motor may be controlled.

Patent
27 May 1981
TL;DR: In this article, the stator is divided into pairs of angular pie-shaped segments, one member of each pair being shifted angularly with respect to the other member of the pair a distance equal to one-half of one pole pitch.
Abstract: An apparatus which reduces magnetic cogging between a rotor and stator of an electrical motor or generator. The stator is divided into pairs of angular pie-shaped segments, one member of each pair being shifted angularly with respect to the other member of the pair a distance equal to one-half of one pole pitch. This places the teeth of a shifted stator segment between the alternating magnetic poles of the rotor while the teeth of the unshifted segment are directly opposite the poles. When the rotor is moved, the reluctance torque, or magnetic cogging due to one member of a pair, virtually cancels the reluctance torque of the other member of the pair.

Patent
19 Aug 1981
TL;DR: In this article, a permanent magnet rotor configuration which produces two magnetic poles is presented. Two pairs of axial slots are provided in which permanent magnets are arranged about the rotor shaft, and a third, diametrically opposed pair of slots is provided which extend radially outwardly and in which regular magnets are disposed.
Abstract: A permanent magnet rotor configuration which produces two magnetic poles. Two pairs of axial slots are provided in which permanent magnets are arranged about the rotor shaft. A third, diametrically opposed pair of slots is provided which extend radially outwardly and in which permanent magnets are disposed. Off-axis magnetic bridges are formed on either side of the third slots, separating them from the first and second sets of slots.

Patent
27 Jul 1981
TL;DR: In this paper, a stator assembly for a turbomachine having a sealing plate which co-operates with sealing members on an adjacent rotor assembly to form air seals is described.
Abstract: A stator assembly for a turbomachine having a sealing plate which co-operates with sealing members on an adjacent rotor assembly to form air seals. The sealing plate is provided with a thermal slugging mass, the thermal response of which controls the rate of expansion and contraction of the sealing plate to match that of the rotor. In this way tip clearances between the stationary and rotating parts of the air seals are maintained substantially uniform throughout all operating conditions of the turbomachine.

Patent
09 Feb 1981
TL;DR: In this paper, a polyphase, brushless dc electric motor with a programmed microprocessor responds to signals indicative of rotor position and rotational speed to selectively energize the windings of the motor and effect a desired speed.
Abstract: Control apparatus for a polyphase, brushless dc electric motor includes a programmed microprocessor which responds to signals indicative of rotor position and rotational speed to selectively energize the windings of the motor and effect a desired speed. The apparatus is compact, readily fabricated, and more reliable than hardwired control circuitry.


Journal ArticleDOI
TL;DR: In this article, a laser anomometer system employing an efficient data acquisition technique has been used to make measurements upstream, within, and downstream of the compressor rotor using fluorescent dye technique.
Abstract: A laser anomometer system employing an efficient data acquisition technique has been used to make measurements upstream, within, and downstream of the compressor rotor. A fluorescent dye technique allowed measurements within endwall boundary layers. Adjustable laser beam orientation minimized shadowed regions and enabled radial velocity measurements outside of the blade row. The flow phenomena investigated include flow variations from passage to passage, the rotor shock system, three-dimensional flows in the blade wake, and the development of the outer endwall boundary layer. Laser anemometer measurements are compared to a numerical solution of the streamfunction equations and to measurements made with conventional instrumentation.

Patent
02 Dec 1981
TL;DR: A driving mechanism for magnetic hard disc memories includes an isolated space for maximum cleanness, a driving motor mounted within the apparatus and having a stator and a rotor, the motor when energized having parts producing magnetic flux, a hub extending into the space of maximum cleaning for receiving therein at least one magnetic hard memory disc, a connection between the motor and the hub for driving the hub, a magnetic flux shield located between the parts producing the magnetic flux and the space, and the rotor being detachably connected to the rotor shaft.
Abstract: A driving mechanism for magnetic hard disc memories includes an isolated space for maximum cleanness, a driving motor mounted within the apparatus and having a stator and a rotor, the motor when energized having parts producing magnetic flux, a hub extending into the space of maximum cleanness for receiving therein at least one magnetic hard memory disc, a connection between the motor and the hub for driving the hub, a magnetic flux shield located between the parts producing the magnetic flux and the space of maximum cleanness, and the rotor being detachably connected to the rotor shaft.