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Component performance investigation of J71 experimental turbine IX: effect of first-stator adjustment;internal flow conditions of J71-97 turbine with 87-percent-design stator area

Description: From Summary: "An experimental radial-survey investigation of the J71-97 three-stage turbine equipped with a first stator having a throat area 87 percent of the design value was conducted at one turbine operating point. The first-, second-, and third-stage mass-averaged efficiencies were 0.897, 0.843, and 0.755, respectively. The corresponding over-all turbine efficiency was 0.856."
Date: April 30, 1957
Creator: Schum, Harold J.; Petrash, Donald A. & Davison, Elmer H.
Partner: UNT Libraries Government Documents Department

Component performance investigation of J71 experimental turbine: IV - Effect of first-stator adjustment; over-all performance of J71-97 turbine with 132-percent-design stator area

Description: An experimental invesitgation of the effect of increasing the first-stator area of the J71-97 experimental three-stage turbine from 97 percent of design to 132 percent revealed (1) the maximum efficiency obtained decreased from 0.891 to 0.869, (2) the choking equivalent weight flows increased by approximately 13.6 percent, and (3) at the turbine match points required to maintain the compressor at constant design equivalent conditions the turbine efficiency decreased from 0.87 to 0.86.
Date: April 17, 1956
Creator: Davison, Elmer H.; Petrash, Donald A. & Schum, Harold J.
Partner: UNT Libraries Government Documents Department

Investigation of semivaneless turbine stator designed to produce axially symmetrical free-vortex flow

Description: From Summary: "A semivaneless turbine stator designed to eliminate blade wakes and secondary-flow accumulations of boundary-layer air was built and tested. Performance of this stator was evaluated with static pressures measured in the vaneless section and surveys of total pressure and flow angle made at the stator exit. Results are presented in terms of theoretical and experimental velocities and flow angles, boundary-layer parameters, and contours of total-pressure loss across the stator."
Date: April 1957
Creator: Rohlik, Harold E. & Wintucky, William T.
Partner: UNT Libraries Government Documents Department

Investigation of a 0.6 hub-tip radius-ratio transonic turbine designed for secondary-flow study 2: design and experimental performance of turbine with low-velocity-turning stator and standard rotor

Description: Report presenting a low-velocity-turning stator designed to reduce secondary-flow loss cores by turning the flow at low velocities and accelerating it in passages of constant flow angle with reduced cross-channel pressure gradients. Turbine performance was measured to determine the effect of low-velocity turning in the stator on the overall turbine performance. Results regarding the stator performance, overall turbine performance, and rotor exit surveys are provided.
Date: July 18, 1957
Creator: Rohlik, Harold E.; Wintucky, William T. & Scribbe, Herbert W.
Partner: UNT Libraries Government Documents Department

Performance of an impulse-type supersonic compressor with stators

Description: Report presenting testing of an impulse-type supersonic compressor rotor with stators tested in Freon-12 over a range of equivalent tip speeds and weight flows. A static pressure ratio of 1.83 and an efficiency of 84.7 percent were obtained at 69.1 percent of the design speed of 1604 feet per second in air.
Date: April 28, 1952
Creator: Klapproth, John F.; Ullman, Guy N. & Tysl, Edward R.
Partner: UNT Libraries Government Documents Department

Stator for Rotating Electrical Machine Having Multiple Controlwindings

Description: A rotating electric machine is provided which includes multiple independent control windings for compensating for rotor imbalances and for levitating/centering the rotor. The multiple independent control windings are placed at different axial locations along the rotor to oppose forces created by imbalances at different axial locations along the rotor. The multiple control windings can also be used to levitate/center the rotor with a relatively small magnetic field per unit area since the rotor and/or the main power winding provides the biasfield.
Date: May 5, 1999
Creator: Shah, Manoj R. & Lewandowski, Chad R.
Partner: UNT Libraries Government Documents Department

Design and Development of a 100 MVA HTS Generator for Commercial Entry

Description: In 2002, General Electric and the US Department of Energy (DOE) entered into a cooperative agreement for the development of a commercialized 100 MVA generator using high temperature superconductors (HTS) in the field winding. The intent of the program was to: (1) identify and develop technologies that would be needed for such a generator; (2) develop conceptual designs for generators with ratings of 100 MVA and higher using HTS technology; (3) perform proof of concept tests at the 1.5 MW level for GE's proprietary warm iron rotor HTS generator concept; and (4) design, build, and test a prototype of a commercially viable 100 MVA generator that could be placed on the power grid. This report summarizes work performed during the program and is provided as one of the final program deliverables. The design for the HTS generator was based on GE's warm iron rotor concept in which a cold HTS coil is wound around a warm magnetic iron pole. This approach for rotating HTS electrical machinery provides the efficiency benefits of the HTS technology while addressing the two most important considerations for power generators in utility applications: cost and reliability. The warm iron rotor concept uses the least amount of expensive HTS wire compared to competing concepts and builds on the very high reliability of conventional iron core stators and armature windings.
Date: June 7, 2007
Partner: UNT Libraries Government Documents Department

Study of Advantages of PM Drive Motor with Selectable Windings for HEVs

Description: The gains in efficiency and reduction in battery costs that can be achieved by changing the effective number of stator turns in an electric motor are demonstrated by simulating the performance of an electric vehicle on a set of eight standard driving cycles.
Date: November 1, 2007
Creator: Otaduy, Pedro J; Hsu, John S & Adams, Donald J
Partner: UNT Libraries Government Documents Department

Corona and Motor Voltage Interim Report

Description: It has been suggested that to meet the FreedomCAR objectives for cost, size, weight, efficiency, and reliability higher buss voltages be utilized in HEV and FC automotive applications. The reasoning is that since electric power is equal to the product of voltage and current for a given power a higher voltage and lower current would result in smaller cable and inverter switching components. Consequently, the system can be lighter and smaller. On the other hand, higher voltages are known to require better and thicker electrical insulation that reduce the available slot area for motor windings. One cause of slow insulation breakdown is corona that gradually erodes the insulation and shortens the life expectancy of the motor. This study reports on the results of a study on corona initiating voltages for mush-wound and bobbin-wound stators. A unique testing method is illustrated.
Date: May 6, 2005
Creator: Hsu, J.S.
Partner: UNT Libraries Government Documents Department


Description: The occurrence of a fault April 7 caused a short in the stator winding of one of the main generators. Repairs will require at least one month and the total time the generator will be down can be determined only after a further inspection of the damage. In a week or two, after a thorough inspection of the generator and the ignitron system, Bevatron operation will be continued on one generator. Since the targets of use in a Bevatron experiment will depend greatly on the nature of the experiment and the techniques to be employed the ideas presented here relate primarily to the area of research which involves the detection with counters of heavy mesons emitted in the backward direction in the laboratory system. These mesons and their decay products have low kinetic energy over the entire range of Bevatron energies above threshold for production. For this reason discrimination by means of momentum resolution, collimating slits, ionization density and range will be possible.
Date: April 13, 1954
Creator: Lofgren, E.J.
Partner: UNT Libraries Government Documents Department

Wedge and spring assembly for securing coils in electromagnets and dynamoelectric machines

Description: A wedge and spring assembly for use in electromagnets or dynamoelectric machines having a housing with an axis therethrough and a plurality of coils supported on salient poles that extend radially inward from the housing toward the housing axis to define a plurality of interpole spaces, respectively between the housing and adjacent coils, the interpole spaces each extending in a direction generally parallel to the housing axis. The wedge and spring assembly includes a nonmagnetic retainer spring and a nonmagnetic wedge. The retainer spring is formed to fit into one of the interpole spaces, and has juxtaposed ends defining between them a slit extending in a direction generally parallel to the housing axis. The wedge for insertion into the slit provides an outwardly directed force on respective portions of the juxtaposed ends defining the slit to expand the slit so that respective portions of the retainer spring engage areas of the coils adjacent thereto, thereby resiliently holding the coils against their respective salient poles. Preferably, the spring retainer and wedge are self-locking wherein wedge is fabricated from a material softer than a material the retainer spring is fabricated from, so that the wedge is securely retained in the slit. The retainer spring is generally triangular shaped to fit within the interpole space and fabricated from berryllium-copper alloy, and the wedge is generally T-shaped and fabricated from aluminum. Alternatively, a wedge and spring assembly includes a wedge having divergent sloped surfaces in which each surface and the respective juxtaposed ends of the retainer spring are angled relative to one another so that the wedge is securely retained in the slit by friction existing between its sloped surfaces and the juxtaposed ends of the retaining spring.
Date: December 31, 1994
Creator: Lindner, M. & Cottingham, J.G.
Partner: UNT Libraries Government Documents Department

Flow and heat transfer in gas turbine disk cavities subject to nonuniform external pressure field

Description: Ingestion of hot gas from the main-stream gas path into turbine disk cavities, particularly the first-stage disk cavity, has become a serious concern for the next-generation industrial gas turbines features high rotor inlet temperature. Fluid temperature in the cavities increases further due to windage generated by fluid drag at the rotating and stationary surfaces. The resulting problem of rotor disk heat-up is exacerbated by the high disk rim temperature due to adverse (relatively flat) temperature profile of the mainstream gas in the annular flow passage of the turbine. This describes an investigation into local convective heat transfer coefficient and cooling effectiveness of the rotor disk, flow field in the disk cavity, computation of the flow field and heat transfer in the disk cavity, and mainstream gas injection and rotor disk cooling effectiveness by mass transfer analogy.
Date: December 31, 1995
Creator: Roy, R. P.; Kim, Y. W. & Tong, T. W.
Partner: UNT Libraries Government Documents Department

Effects of stator and rotor core ovality on induction machine behavior

Description: Asymmetries in the air gap of induction motors produce additional harmonics in the flux density and force waves. A complete transient finite element model analyzes the harmonics produced from two possible asymmetries, a stator core ovality and a rotor ovality. The analysis of the air gap flux density and magnetic force waves determined by the finite element model shows unique harmonic frequencies due to the ovality of the air gap.
Date: September 1, 1996
Creator: Salon, S.J.; Burow, D.W.; DeBortoli, M.J. & Slavik, C.J.
Partner: UNT Libraries Government Documents Department

Reduced vibration motor winding arrangement

Description: The present invention relates generally to an electric motor winding and, more particularly, to a three phase motor armature winding arrangement designed to reduce motor vibration and improve efficiency. An individual phase winding arrangement having a sixty electrical degree phase belt width for use with a three phase motor armature includes a delta connected phase winding portion and a wye connected phase winding portion. Both the delta and wye connected phase winding portions have a thirty electrical degree phase belt width. The delta and wye connected phase winding portions are each formed from a preselected number of individual coils each formed, in turn, from an unequal number of electrical conductor turns in the approximate ratio of {radical}3. The individual coils of the delta and wye connected phase winding portions may either be connected in series or parallel. This arrangement provides an armature winding for a three phase motor which retains the benefits of the widely known and utilized thirty degree phase belt concept, including improved mmf waveform and fundamental distribution factor.
Date: December 31, 1995
Creator: Slavik, C.J.; Rhudy, R.G. & Bushman, R.E.
Partner: UNT Libraries Government Documents Department

Effects of stator and rotor core ovality on induction machine behavior

Description: Asymmetries in the air gap of induction motors produce additional harmonics in the flux density and force waves. A complete transient finite element model analyzes the harmonics produced from two possible asymmetries, a stator core ovality and a rotor ovality. The analysis of the air gap flux density and magnetic force waves determined by the finite element model shows unique harmonic frequencies due to the ovality of the air gap.
Date: July 1, 1995
Creator: Salon, S.J. & Burow, D.W.
Partner: UNT Libraries Government Documents Department

Multilevel DC Link Inverter for Brushless Permanent Magnet Motors with Very Low Inductance

Description: Due to their long effective air gaps, permanent magnet motors tend to have low inductance. The use of ironless stator structure in present high power PM motors (several tens of kWs) reduces the inductance even further (< 100 {micro}H). This low inductance imposes stringent current regulation demands for the inverter to obtain acceptable current ripple. An analysis of the current ripple for these low inductance brushless PM motors shows that a standard inverter with the most commonly used IGBT switching devices cannot meet the current regulation demands and will produce unacceptable current ripples due to the IGBT's limited switching frequency. This paper introduces a new multilevel dc link inverter, which can dramatically reduce the current ripple for brushless PM motor drives. The operating principle and design guidelines are included.
Date: October 29, 2001
Creator: Su, G. J.
Partner: UNT Libraries Government Documents Department

A Field Theory Approach to Modeling Helical FCG's

Description: Often helical flux-compressor generator (FCG) design codes are essentially circuit codes which utilize known equations for parameterizing circuit elements such as armature and stator inductance. The authors present an analytical model that is based more on first principals. The stator inductance is calculated using a definition of inductance in terms of the magnetic vector-potential. The calculation accounts for winding-pitch, bifurcations, and works for any ratio of length to diameter. The currents on the armature are calculated self-consistently and are not assumed to simply 'mirror' the stator currents. Resistive losses and magnetic diffusion losses are calculated less rigorously but they are working on better methods. Details of the model and comparison with experiment will be presented.
Date: October 18, 1998
Creator: Fortgang, C.M.
Partner: UNT Libraries Government Documents Department

Modeling and Simulation of Miniature Piezoelectric Motors

Description: The use of piezo materials is becoming common in both commercial and retail products. Motors designed using piezo materials as actuators are also being utilized where either space or magnetic materials are limited. This paper discusses the use of ABAQUS/Standard and ABAQUS/Explicit toward the development and production of small piezo motors. Analytical techniques are the only methods possible to determine motor design parameters and performance issues prior to prototype production and testing. The use of ABAQUS/Standard to solve baseline Eigenvalue extractions and transient dynamics for stator motion has made it possible to evaluate motor designs much quicker than physical evaluations. The use of the ''VUMAT'' subroutine in ABAQUS/Explicit has been used to create strains driven by the piezo effects, thus allowing for many thousands of cyclic loads to be applied to contacting 3D continuum structures. The use of viscous pressure techniques for near-perfect static loading under explicit dynamics will also be presented and discussed.
Date: June 1, 1998
Creator: Mahoney, J.F.
Partner: UNT Libraries Government Documents Department

Rotating Aperture System

Description: A rotating aperture system includes a low-pressure vacuum pumping stage with apertures for passage of a deuterium beam. A stator assembly includes holes for passage of the beam. The rotor assembly includes a shaft connected to a deuterium gas cell or a crossflow venturi that has a single aperture on each side that together align with holes every rotation. The rotating apertures are synchronized with the firing of the deuterium beam such that the beam fires through a clear aperture and passes into the Xe gas beam stop. Portions of the rotor are lapped into the stator to improve the sealing surfaces, to prevent rapid escape of the deuterium gas from the gas cell.
Date: January 18, 2005
Creator: Rusnak, Brian; Hall, James M.; Shen, Stewart & Wood, Richard L.
Partner: UNT Libraries Government Documents Department

Optimizing the Ranchero Coaxial Flux Compression Generator

Description: Ranchero is an explosively driven magnetic flux-compression generator that has been developed, over the last four years, as a versatile power source for high energy density physics experiments. It is coaxial, and comprises a 15 cm-diameter armature and a 30-cm stator, each aluminum. The length may be varied to suit the demands of each experiment; thus far, lengths of 0.43 m and 1.4 m have been used. The stator is filled and driven by a high performance cast explosive, and the ultimate performance of the device is limited by the smoothness of the armature expansion. The armature explosive is initiated on axis by PETN hemispheres, spaced at intervals of about 18 mm and 24.5 mm; each is simultaneously detonated by a slapper detonator system. Calculations of armature expansion predicted ripples less than 0.2 mm, and this was confirmed in early experiments. Yet, ripples approaching tens of millimeters were observed in some more recent experiments. The authors discuss the possible origins of the se large ripples, and the methods the authors have used to correct them.
Date: October 18, 1998
Creator: Tasker, D.G.; Goforth, J.H.; Fowler, C.M.; Lopez, E.A.; Oona, H.; King, J.C. et al.
Partner: UNT Libraries Government Documents Department

Modular PM Motor Drives for Automotive Traction Applications

Description: This paper presents modular permanent magnet (PM) motor drives for automotive traction applications. A partially modularized drive system consisting of a single PM motor and multiple inverters is described. The motor has multiple three-phase stator winding sets and each winding set is driven with a separate three-phase inverter module. A truly modularized inverter and motor configuration based on an axial-gap PM motor is then introduced, in which identical PM motor modules are mounted on a common shaft and each motor module is powered by a separate inverter module. The advantages of the modular approach for both inverter and motor include: (1) power rating scalability--one design meets different power requirements by simply stacking an adequate number of modules, thus avoiding redesigning and reducing the development cost, (2) increased fault tolerance, and (3) easy repairing. A prototype was constructed by using two inverters and an axial-gap PM motor with two sets of three-phase stat or windings, and it is used to assist the diesel engine in a hybrid electric vehicle converted from a Chevrolet Suburban. The effect of different pulse-width-modulation strategies for both motoring and regenerative modes on current control is analyzed. Torque and regenerative control algorithms are implemented with a digital signal processor. Analytical and initial testing results are included in the paper.
Date: October 29, 2001
Creator: Su, G.J.
Partner: UNT Libraries Government Documents Department

Piezoelectric theory for finite element analysis of ultrasonic motors

Description: The authors present the fundamental equations of piezoelectricity and references. They show how a second form of the equations and a second set of coefficients can be found, through inversions involving the elasticity tensor. They show how to compute the clamped permittivity matrix from the unclamped matrix. The authors list the program pzansys.ftn and present examples of its use. This program does the conversions and calculations needed by the finite element program ANSYS.
Date: June 1, 1997
Creator: Emery, J.D. & Mentesana, C.P.
Partner: UNT Libraries Government Documents Department

Trapped-flux internal-dipole superconducting motor/generator.

Description: A new class of motor/generator (M/G) utilizes the magnetic flux trapping capability of high-temperature superconductors (HTSs). The rotor, consists of a cylindrical shell composed of HTS segments. These segments act as trapped-field magnets, magnetized in such a way that a dipole magnetic field is produced in the interior of the shell. A stator coil assembly is placed in the interior of the shell and current passing through the conductors of the coil produce a rotational torque, either as a hysteresis motor or as a synchronous motor. The coil may be either conventional, with copper wires and an iron core, or composed of superconductors and can be used to establish the trapped fields in the HTSs.
Date: September 3, 1998
Creator: Hull, J. R.
Partner: UNT Libraries Government Documents Department

Direct Lamination Cooling of Motors For Electric Vehicles

Description: Current designs for electric motors use a housing that acts as both a structural support and as a method of cooling the stator and rotor. This approach to cooling is not as effective as possible because heat must flow from the rotor and stator through the housing to the cooling media. Because the housing must contain the coolant, it is also larger, heavier, and more expensive than necessary. This project develops a motor that uses a direct lamination cooling (DLC) system, passing coolant directly through the stator and eliminating the need for bulky housing, thereby improving heat transfer. Motor size could be reduced by up to 30-40%, mass by up to 20-30%, and cost by up to 30%. Phase I demonstrated that reliable lamination-to-lamination seals and reliable stack-to-manifold seals can be achieved using the methods identified. The addition of the selected sealants adds only slightly to the thermal resistance and pressure drop compared with unsealed counterparts. Phase II builds electric motors and inductors using the DLC method, obtain comparative performance data on the effectiveness of the method, and then obtain operational use data on these components through long term testing in a representative environment. The long-term testing will ensure that real world aspects of motor and inductor operation (including vibration, temperature cycling, and the presence of electrical and magnetic fields) do not degrade the seals such that leaking occurs or that the thermal performance degrades.
Date: July 30, 2003
Creator: Rippel, Wally & Kobayashi, Drayll
Partner: UNT Libraries Government Documents Department