Axial flux machine, stator and fabrication method

DOEpatents

Carl, Ralph James

2004-03-16

An axial flux machine comprises: a soft magnetic composite stator extension positioned in parallel with a rotor disk and having slots; soft magnetic composite pole pieces attached to the stator extension and facing a permanent magnet on the rotor disk, each comprising a protrusion situated within a respective one of the slots, each protrusion shaped so as to facilitate orientation of the respective pole piece with respect to the stator extension; electrical coils, each wrapped around a respective one of the pole pieces. In another embodiment the soft magnetic composite pole pieces each comprise a base portion around with the electrical coils are wound and a trapezoidal shield portion a plurality of heights with a first height in a first region being longer than a second height in a second region, the second region being closer to a pole-to-pole gap than the first region.

Welding fixture for joining bar-wound stator conductors

DOE Office of Scientific and Technical Information (OSTI.GOV)

De Souza, Urban J.; Rhoads, Frederick W.; Hanson, Justin

A fixture assembly for welding a plurality of stator wire end pairs may include an anvil, a movable clamp configured to translate between an unclamped state and a clamped state, a first grounding electrode, and a second grounding electrode. The movable clamp may be configured to urge the plurality of stator wire ends against the anvil when in the clamped state. The moveable clamp includes a separator feature that generally extends toward the anvil. Each of the first grounding electrode and second grounding electrodes may be configured to translate between a clamped state and an unclamped state. When in themore » clamped state, each of the first and second grounding electrodes is configured to urge a pair of the plurality of stator wire end pairs against the separator feature.« less

Electrical stator

DOEpatents

Fanning, Alan W.; Olich, Eugene E.

1994-01-01

An electrical stator of an electromagnetic pump includes first and second spaced apart coils each having input and output terminals for carrying electrical current. An elongate electrical connector extends between the first and second coils and has first and second opposite ends. The connector ends include respective slots receiving therein respective ones of the coil terminals to define respective first and second joints. Each of the joints includes a braze filler fixedly joining the connector ends to the respective coil terminals for carrying electrical current therethrough.

Off-design performance loss model for radial turbines with pivoting, variable-area stators

NASA Technical Reports Server (NTRS)

Meitner, P. L.; Glassman, A. J.

1980-01-01

An off-design performance loss model was developed for variable stator (pivoted vane), radial turbines through analytical modeling and experimental data analysis. Stator loss is determined by a viscous loss model; stator vane end-clearance leakage effects are determined by a clearance flow model. Rotor loss coefficient were obtained by analyzing the experimental data from a turbine rotor previously tested with six stators having throat areas from 20 to 144 percent of design area and were correlated with stator-to-rotor throat area ratio. An incidence loss model was selected to obtain best agreement with experimental results. Predicted turbine performance is compared with experimental results for the design rotor as well as with results for extended and cutback versions of the rotor. Sample calculations were made to show the effects of stator vane end-clearance leakage.

Superconducting electromechanical rotating device having a liquid-cooled, potted, one layer stator winding

DOEpatents

Dombrovski, Viatcheslav V.; Driscoll, David I.; Shovkhet, Boris A.

2001-01-01

A superconducting electromechanical rotating (SER) device, such as a synchronous AC motor, includes a superconducting field winding and a one-layer stator winding that may be water-cooled. The stator winding is potted to a support such as the inner radial surface of a support structure and, accordingly, lacks hangers or other mechanical fasteners that otherwise would complicate stator assembly and require the provision of an unnecessarily large gap between adjacent stator coil sections. The one-layer winding topology, resulting in the number of coils being equal to half the number of slots or other mounting locations on the support structure, allows one to minimize or eliminate the gap between the inner radial ends of adjacent straight sections of the stator coilswhile maintaining the gap between the coil knuckles equal to at least the coil width, providing sufficient room for electrical and cooling element configurations and connections. The stator winding may be potted to the support structure or other support, for example, by a one-step VPI process relying on saturation of an absorbent material to fill large gaps in the stator winding or by a two-step process in which small gaps are first filled via a VPI or similar operation and larger gaps are then filled via an operation that utilizes the stator as a portion of an on-site mold.

Double-stator electromagnetic pump having alignment ring and spine assembly

DOEpatents

Fanning, Alan Wayne; Olich, Eugene Ellsworth; Dahl, Leslie Roy; Patel, Mahadeo Ratilal

1997-01-01

A support structure for clamping the inner coils and inner lamination rings of an inner stator column of an electromagnetic induction pump to prevent damaging vibration. A spine assembly, including a base plate, a center post and a plurality of ribs, serves as the structural frame for the inner stator. Stacked alignment rings provide structure to the lamination rings and locate them concentrically around the spine assembly central axis. The alignment rings are made of a material having a high thermal expansion coefficient to compensate for the lower expansion of the lamination rings and, overall, provide an approximate match to the expansion of the inner flow duct. The net result is that the radial clamping provided by the duct around the stator iron is maintained (approximately) over a range of temperatures and operating conditions. Axial clamping of the inner stator structure is achieved via tie rods which run through grooves in the ribs and engage the base plate at the bottom of the inner stator and engage a clamping plate at the top. Slender tie rods and a flexible clamping plate are used to provide compliance in the axial clamping system to accommodate differential thermal growth (axially) between the tie rods and lamination ring elements without losing clamping force.

Double-stator electromagnetic pump having alignment ring and spine assembly

DOEpatents

Fanning, A.W.; Olich, E.E.; Dahl, L.R.; Patel, M.R.

1997-06-24

A support structure for clamping the inner coils and inner lamination rings of an inner stator column of an electromagnetic induction pump to prevent damaging vibration is disclosed. A spine assembly, including a base plate, a center post and a plurality of ribs, serves as the structural frame for the inner stator. Stacked alignment rings provide structure to the lamination rings and locate them concentrically around the spine assembly central axis. The alignment rings are made of a material having a high thermal expansion coefficient to compensate for the lower expansion of the lamination rings and, overall, provide an approximate match to the expansion of the inner flow duct. The net result is that the radial clamping provided by the duct around the stator iron is maintained (approximately) over a range of temperatures and operating conditions. Axial clamping of the inner stator structure is achieved via tie rods which run through grooves in the ribs and engage the base plate at the bottom of the inner stator and engage a clamping plate at the top. Slender tie rods and a flexible clamping plate are used to provide compliance in the axial clamping system to accommodate differential thermal growth (axially) between the tie rods and lamination ring elements without losing clamping force. 12 figs.

Aeropropulsion Technology (APT). Task 23 - Stator Seal Cavity Flow Investigation

NASA Technical Reports Server (NTRS)

Heidegger, N. J.; Hall, E. J.; Delaney, R. A.

1996-01-01

The focus of NASA Contract NAS3-25950 Task 23 was to numerically investigate the flow through an axial compressor inner-banded stator seal cavity. The Allison/NASA developed ADPAC code was used to obtain all flow predictions. Flow through a labyrinth stator seal cavity of a high-speed compressor was modeled by coupling the cavity flow path and the main flow path of the compressor. A grid resolution study was performed to guarantee adequate grid spacing was used. Both unsteady rotor-stator-rotor interactions and steady-state isolated blade calculations were performed with and without the seal cavity present. A parameterized seal cavity study of the high-speed stator seal cavity collected a series of solutions for geometric variations. The parameter list included seal tooth gap, cavity depth, wheel speed, radial mismatch of hub flowpath, axial trench gap, hub corner treatments, and land edge treatments. Solution data presented includes radial and pitchwise distributions of flow variables and particle traces describing the flow character.

Loss model for off-design performance analysis of radial turbines with pivoting-vane, variable-area stators

NASA Technical Reports Server (NTRS)

Meitner, P. L.; Glassman, A. J.

1980-01-01

An off-design performance loss model is developed for variable-area (pivoted vane) radial turbines. The variation in stator loss with stator area is determined by a viscous loss model while the variation in rotor loss due to stator area variation (for no stator end-clearance gap) is determined through analytical matching of experimental data. An incidence loss model is also based on matching of the experimental data. A stator vane end-clearance leakage model is developed and sample calculations are made to show the predicted effects of stator vane end-clearance leakage on performance.

Acoustic Benefits of Stator Sweep and Lean for a High Tip Speed Fan

NASA Technical Reports Server (NTRS)

Woodward, Richard P.; Gazzaniga, John A.; Bartos, Linda J.; Hughes, Christopher E.

2002-01-01

A model high-speed fan stage was acoustically tested in the NASA Glenn 9- by 15-Foot Low Speed Wind Tunnel at takeoff/approach flight conditions. The fan was designed for a corrected rotor tip speed of 442 m/s (1450 ft/s), and had a powered core, or booster stage, giving the model a nominal bypass ratio of 5. The model also had a simulated engine pylon and nozzle bifurcation contained within the bypass duct. The fan was tested with three stator sets to evaluate acoustic benefits associated with a swept and leaned stator and with a swept integral vane/frame stator which incorporated some of the swept and leaned features as well as eliminated some of the downstream support structure. The baseline fan with the wide chord rotor and baseline stator approximated a current GEAE CF6 engine. A flyover effective perceived noise level (EPNL) code was used to generate relative EPNL values for the various configurations. Flyover effective perceived noise levels (EPNL) were computed from the model data to help project noise benefits. A tone removal study was also performed. The swept and leaned stator showed a 3 EPNdB reduction at lower fan speeds relative to the baseline stator; while the swept integral vane/frame stator showed lowest noise levels at intermediate fan speeds. Removal of the bypass blade passage frequency rotor tone (BPF) showed a 4 EPNdB reduction for the baseline and swept and leaned stators, and a 6 EPNdB reduction for the swept integral vane/ frame stator. Therefore, selective tone removal techniques such as active noise control and/or tuned liner could be particularly effective in reducing noise levels for certain fan speeds.

Study of controlled diffusion stator blading. 1. Aerodynamic and mechanical design report

NASA Technical Reports Server (NTRS)

Canal, E.; Chisholm, B. C.; Lee, D.; Spear, D. A.

1981-01-01

Pratt & Whitney Aircraft is conducting a test program for NASA in order to demonstrate that a controlled-diffusion stator provides low losses at high loadings and Mach numbers. The technology has shown great promise in wind tunnel tests. Details of the design of the controlled diffusion stator vanes and the multiple-circular-arc rotor blades are presented. The stage, including stator and rotor, was designed to be suitable for the first-stage of an advanced multistage, high-pressure compressor.

Rotor Wake/Stator Interaction Noise Prediction Code Technical Documentation and User's Manual

NASA Technical Reports Server (NTRS)

Topol, David A.; Mathews, Douglas C.

2010-01-01

This report documents the improvements and enhancements made by Pratt & Whitney to two NASA programs which together will calculate noise from a rotor wake/stator interaction. The code is a combination of subroutines from two NASA programs with many new features added by Pratt & Whitney. To do a calculation V072 first uses a semi-empirical wake prediction to calculate the rotor wake characteristics at the stator leading edge. Results from the wake model are then automatically input into a rotor wake/stator interaction analytical noise prediction routine which calculates inlet aft sound power levels for the blade-passage-frequency tones and their harmonics, along with the complex radial mode amplitudes. The code allows for a noise calculation to be performed for a compressor rotor wake/stator interaction, a fan wake/FEGV interaction, or a fan wake/core stator interaction. This report is split into two parts, the first part discusses the technical documentation of the program as improved by Pratt & Whitney. The second part is a user's manual which describes how input files are created and how the code is run.

Loss model for off-design performance analysis of radial turbines with pivoting-vane, variable-area stators

NASA Technical Reports Server (NTRS)

Meitner, P. L.; Glassman, A. J.

1980-01-01

An off-design performance loss model for a radial turbine with pivoting, variable-area stators is developed through a combination of analytical modeling and experimental data analysis. A viscous loss model is used for the variation in stator loss with setting angle, and stator vane end-clearance leakage effects are predicted by a clearance flow model. The variation of rotor loss coefficient with stator setting angle is obtained by means of an analytical matching of experimental data for a rotor that was tested with six stators, having throat areas from 20 to 144% of the design area. An incidence loss model is selected to obtain best agreement with experimental data. The stator vane end-clearance leakage model predicts increasing mass flow and decreasing efficiency as a result of end-clearances, with changes becoming significantly larger with decreasing stator area.

Status of the Ford program to evaluate ceramics for stator applications in automotive gas turbine engines

NASA Technical Reports Server (NTRS)

Trela, W.

1980-01-01

The paper reviews the progress of the major technical tasks of the DOE/NASA/Ford program Evaluation of Ceramics for Stator Applications in Automotive Gas Turbine Engines: reliability prediction, stator fabrication, material characterization, and stator evaluation. A fast fracture reliability model was prepared for a one-piece ceramic stator. Periodic inspection results are presented.

Electrical machines and assemblies including a yokeless stator with modular lamination stacks

DOEpatents

Qu, Ronghai; Jansen, Patrick Lee; Bagepalli, Bharat Sampathkumar; Carl, Jr., Ralph James; Gadre, Aniruddha Dattatraya; Lopez, Fulton Jose

2010-04-06

An electrical machine includes a rotor with an inner rotor portion and an outer rotor portion, and a double-sided yokeless stator. The yokeless stator includes modular lamination stacks and is configured for radial magnetic flux flow. The double-sided yokeless stator is concentrically disposed between the inner rotor portion and the outer rotor portion of the electrical machine. Examples of particularly useful embodiments for the electrical machine include wind turbine generators, ship propulsion motors, switch reluctance machines and double-sided synchronous machines.

A dynamic model of the piezoelectric traveling wave rotary ultrasonic motor stator with the finite volume method.

PubMed

Renteria Marquez, I A; Bolborici, V

2017-05-01

This manuscript presents a method to model in detail the piezoelectric traveling wave rotary ultrasonic motor (PTRUSM) stator response under the action of DC and AC voltages. The stator is modeled with a discrete two dimensional system of equations using the finite volume method (FVM). In order to obtain accurate results, a model of the stator bridge is included into the stator model. The model of the stator under the action of DC voltage is presented first, and the results of the model are compared versus a similar model using the commercial finite element software COMSOL Multiphysics. One can observe that there is a difference of less than 5% between the displacements of the stator using the proposed model and the one with COMSOL Multiphysics. After that, the model of the stator under the action of AC voltages is presented. The time domain analysis shows the generation of the traveling wave in the stator surface. One can use this model to accurately calculate the stator surface velocities, elliptical motion of the stator surface and the amplitude and shape of the stator traveling wave. A system of equations discretized with the finite volume method can easily be transformed into electrical circuits, because of that, FVM may be a better choice to develop a model-based control strategy for the PTRUSM. Copyright © 2017 Elsevier B.V. All rights reserved.

Clocking of stators in one and half stage of axial steam turbine

NASA Astrophysics Data System (ADS)

Němec, Martin; Jelínek, Tomáš; Milčák, Petr

2018-06-01

An investigation of one and half axial turbine stage configuration was carried out in a closed-loop wind tunnel. The investigation was addressed to that impact how the previous stage outlet flow field influences the flow structures in the next stator in steam multistage turbines. The stage - stator interaction has been studied in this work. The detailed measurement with a pneumatic probes and fast response pressure probes behind the rotor and the second stator were performed to gain the useful data to analyze the impact. The detailed flow field measurement was carried out in the nominal stage regime (given by the stage isentropic Mach number 0.3 and velocity ratio u/c 0.68). The clocking effect of the stators is discussed and detailed unsteady flow analysis is shown.

Effects of blade-vane ratio and rotor-stator spacing of fan noise with forward velocity

NASA Astrophysics Data System (ADS)

Woodward, R. P.; Glaser, F. W.

1981-08-01

A research fan stage was acoustically tested in an anechoic wind tunnel with a 41 m/sec tunnel flow. Two stator vane numbers giving cut-on and cut-off conditions were tested at three rotor-stator spacings ranging from about 0.5 to 2.0 rotor chords. These two stators were designed for similar aerodynamic performance. Hot film anemometer turbulence measurements were made at the leading edge of the stator for each spacing. The cut-off criterion strongly controlled the fundamental tone level at all spacings. The trends with spacing of the wake defect upwash component at the stator tip showed good agreement with the corresponding cut-on acoustic tone levels.

Electromagnetic pump stator core

DOEpatents

Fanning, A.W.; Olich, E.E.; Dahl, L.R.

1995-01-17

A stator core for supporting an electrical coil includes a plurality of groups of circumferentially abutting flat laminations which collectively form a bore and perimeter. A plurality of wedges are interposed between the groups, with each wedge having an inner edge and a thicker outer edge. The wedge outer edges abut adjacent ones of the groups to provide a continuous path around the perimeter. 21 figures.

Electromagnetic pump stator core

DOEpatents

Fanning, Alan W.; Olich, Eugene E.; Dahl, Leslie R.

1995-01-01

A stator core for supporting an electrical coil includes a plurality of groups of circumferentially abutting flat laminations which collectively form a bore and perimeter. A plurality of wedges are interposed between the groups, with each wedge having an inner edge and a thicker outer edge. The wedge outer edges abut adjacent ones of the groups to provide a continuous path around the perimeter.

A Kalman Filter Based Technique for Stator Turn-Fault Detection of the Induction Motors

NASA Astrophysics Data System (ADS)

Ghanbari, Teymoor; Samet, Haidar

2017-11-01

Monitoring of the Induction Motors (IMs) through stator current for different faults diagnosis has considerable economic and technical advantages in comparison with the other techniques in this content. Among different faults of an IM, stator and bearing faults are more probable types, which can be detected by analyzing signatures of the stator currents. One of the most reliable indicators for fault detection of IMs is lower sidebands of power frequency in the stator currents. This paper deals with a novel simple technique for detecting stator turn-fault of the IMs. Frequencies of the lower sidebands are determined using the motor specifications and their amplitudes are estimated by a Kalman Filter (KF). Instantaneous Total Harmonic Distortion (ITHD) of these harmonics is calculated. Since variation of the ITHD for the three-phase currents is considerable in case of stator turn-fault, the fault can be detected using this criterion, confidently. Different simulation results verify high performance of the proposed method. The performance of the method is also confirmed using some experiments.

Hall effect sensors embedded within two-pole toothless stator assembly

NASA Technical Reports Server (NTRS)

Denk, Joseph (Inventor); Grant, Richard J. (Inventor)

1994-01-01

A two-pole toothless PM machine employs Hall effect sensors to indicate the position of the machine's rotor relative to power windings in the machine's stator. The Hall effect sensors are located in the main magnetic air gap underneath the power windings. The main magnetic air gap is defined by an outer magnetic surface of the rotor and an inner surface of the stator's flux collector ring.

Experimental and Numerical Study on Performance of Ducted Hydrokinetic Turbines with Pre-Swirl Stator Blades.

NASA Astrophysics Data System (ADS)

Gish, Andrew

2015-11-01

Ducts (also called shrouds) have been shown to improve performance of hydrokinetic turbines in some situations, bringing the power coefficient (Cp) closer to the Betz limit. Here we investigate optimization of the duct design as well as the addition of stator blades upstream of the turbine rotor to introduce pre-swirl in the flow. A small scale three-bladed turbine was tested in a towing tank. Three cases (bare turbine, with duct, and with duct and stators) were tested over a range of flow speeds. Important parameters include duct cross-sectional shape, blade-duct gap, stator cross-sectional shape, and stator angle. For each test, Cp was evaluated as a function of tip speed ratio (TSR). Experimental results were compared with numerical simulations. Results indicate that ducts and stators can improve performance at slower flow speeds and lower the stall speed compared to a bare turbine, but may degrade performance at higher speeds. Ongoing efforts to optimize duct and stator configurations will be discussed.

SSME seal test program: Test results for smooth, hole-pattern and helically-grooved stators

NASA Technical Reports Server (NTRS)

Childs, Dara W.

1987-01-01

All of the listed seals were tested in a liquid Halon test facility at high Reynolds numbers. In addition, a helically-grooved-stator seal was tested in an air seal facility. An analysis of the test results with comparisons to theoretical predictions supports the following conclusions: (1) For small seals, the Hirs' friction-factor model is more restricted than had been thought; (2) For smooth seals, predictions of stiffness and damping improve markedly as the radical clearance is reduced; (3) Friction-factor data for hole-pattern-seal stators frequently deviates from the Hirs model; (4) Predictions of stiffness and damping coefficients for hole-pattern-stator seals is generally reasonable; (5) Tests for the hole-pattern stators at reduced clearances show no clear optimum for hole-pattern seals with respect to either hole-area ratio or hole depth to minimum clearance ratios; (6) Tests of these hole-pattern stators show no significant advantage in net damping over smooth seals; (7) Tests of helically-grooved seal stators in Halon show reasonable agreement between theory and prediction for leakage and direct stiffness but poor agreement for the net damping coefficient.

Novel modeling technique for the stator of traveling wave ultrasonic motors.

PubMed

Pons, José L; Rodríguez, Humberto; Ceres, Ramón; Calderón, Leopoldo

2003-11-01

Traveling wave ultrasonic motors (TWUM) are a promising type of piezoelectric transducers, which are based on the friction transmission of mechanical propagating waves. These waves are excited on the stator by using high Q piezoelectric ceramics. This article presents a modeling strategy, which allows for a quick and precise modal and forced analysis of the stator of TWUM. First-order shear deformation laminated plate theory is applied to annular subdomains (super-elements) of the stator. In addition to shear deformations, the model takes into account the effect of rotary inertia, the stiffness contribution of the teeth, and the linear varying thickness of the stator. Moreover, the formulation considers a more realistic function for the electric field inside the piezoelectric ceramic, i.e., a linear function, instead of the generally assumed constant electric field. The Ritz method is used to find an approximated solution for the dynamic equations. Finally, the modal response is obtained and compared against the results from classical simplified models and the finite element method. Thus, the high accuracy and short computation times of the novel strategy were demonstrated.

Evaluating transient performance of servo mechanisms by analysing stator current of PMSM

NASA Astrophysics Data System (ADS)

Zhang, Qing; Tan, Luyao; Xu, Guanghua

2018-02-01

Smooth running and rapid response are the desired performance goals for the transient motions of servo mechanisms. Because of the uncertain and unobservable transient behaviour of servo mechanisms, it is difficult to evaluate their transient performance. Under the effects of electromechanical coupling, the stator current signals of a permanent-magnet synchronous motor (PMSM) potentially contain the performance information regarding servo mechanisms in use. In this paper, a novel method based on analysing the stator current of the PMSM is proposed for quantifying the transient performance. First, a vector control model is constructed to simulate the stator current behaviour in the transient processes of consecutive speed changes, consecutive load changes, and intermittent start-stops. It is discovered that the amplitude and frequency of the stator current are modulated by the transient load torque and motor speed, respectively. The stator currents under different performance conditions are also simulated and compared. Then, the stator current is processed using a local means decomposition (LMD) algorithm to extract the instantaneous amplitude and instantaneous frequency. The sample entropy of the instantaneous amplitude, which reflects the complexity of the load torque variation, is calculated as a performance indicator of smooth running. The peak-to-peak value of the instantaneous frequency, which defines the range of the motor speed variation, is set as a performance indicator of rapid response. The proposed method is applied to both simulated data in an intermittent start-stops process and experimental data measured for a batch of servo turrets for turning lathes. The results show that the performance evaluations agree with the actual performance.

A block-based algorithm for the solution of compressible flows in rotor-stator combinations

NASA Technical Reports Server (NTRS)

Akay, H. U.; Ecer, A.; Beskok, A.

1990-01-01

A block-based solution algorithm is developed for the solution of compressible flows in rotor-stator combinations. The method allows concurrent solution of multiple solution blocks in parallel machines. It also allows a time averaged interaction at the stator-rotor interfaces. Numerical results are presented to illustrate the performance of the algorithm. The effect of the interaction between the stator and rotor is evaluated.

Effects of Shrouded Stator Cavity Flows on Multistage Axial Compressor Aerodynamic Performance

NASA Technical Reports Server (NTRS)

Wellborn, Steven R.; Okiishi, Theodore H.

1996-01-01

Experiments were performed on a low-speed multistage axial-flow compressor to assess the effects of shrouded stator cavity flows on aerodynamic performance. Five configurations, which involved changes in seal-tooth leakage rates and/or elimination of the shrouded stator cavities, were tested. Data collected enabled differences in overall individual stage and the third stage blade element performance parameters to be compared. The results show conclusively that seal-tooth leakage ran have a large impact on compressor aerodynamic performance while the presence of the shrouded stator cavities alone seemed to have little influence. Overall performance data revealed that for every 1% increase in the seal-tooth clearance to blade-height ratio the pressure rise dropped up to 3% while efficiency was reduced by 1 to 1.5 points. These observed efficiency penalty slopes are comparable to those commonly reported for rotor and cantilevered stator tip clearance variations. Therefore, it appears that in order to correctly predict overall performance it is equally important to account for the effects of seal-tooth leakage as it is to include the influence of tip clearance flows. Third stage blade element performance data suggested that the performance degradation observed when leakage was increased was brought about in two distinct ways. First, increasing seal-tooth leakage directly spoiled the near hub performance of the stator row in which leakage occurred. Second, the altered stator exit now conditions caused by increased leakage impaired the performance of the next downstream stage by decreasing the work input of the downstream rotor and increasing total pressure loss of the downstream stator. These trends caused downstream stages to progressively perform worse. Other measurements were acquired to determine spatial and temporal flow field variations within the up-and-downstream shrouded stator cavities. Flow within the cavities involved low momentum fluid traveling primarily

Noise produced by the interaction of a rotor wake with a swept stator blade

NASA Astrophysics Data System (ADS)

Envia, E.; Kerschen, E. J.

1984-10-01

An analysis is developed for the noise generated by the interaction of rotor viscous wakes and a single swept stator vane. The stator vane spans a channel with infinite parallel walls which contains a uniform subsonic mean flow. High frequency wakes, for which the noise generation is concentrated at the vane leading edge, are considered. The general wake pattern is expanded in spanwise modes and solutions for each mode are derived using the Wiener-Hopf technique applied to the equations in the nonorthogonal coordinates. Closed form expressions for the acoustic farfield are obtained. The results of the analysis are used in parametric calculations of rotor viscous wake-stator vane interactions in order to study the effectiveness of sweep as a noise reduction mechanism. For the cases studied, moderate stator sweep angles produce sizeable reductions in the level of the farfield noise. The presence of rotor wake circumferential lean actually increases the noise reduction produced by moderate stator sweep angles.

Kilowatt Isotope Power System: component test report for the ground demonstration system alternator stator. 78-KIPS-17

DOE Office of Scientific and Technical Information (OSTI.GOV)

Not Available

1977-12-14

The purpose of this test was to demonstrate that the alternator stator has satisfactorily completed sufficient testing to safisfy the requirements set forth within the Kilowatt Isotope Power System (KIPS) Component Test Specification for the GDS Alternator Stator (TS 2538). The results of the acceptance tests conducted on the alternator stator, S/N 003, are presented, and show that the stator did meet specified requirements.

Banded electromagnetic stator core

DOEpatents

Fanning, Alan W.; Gonzales, Aaron A.; Patel, Mahadeo R.; Olich, Eugene E.

1994-01-01

A stator core for an electromagnetic pump includes a plurality of circumferentially adjoining groups of flat laminations disposed about a common centerline axis and collectively defining a central bore and a discontinuous outer perimeter, with adjacent groups diverging radially outwardly to form V-shaped gaps. An annular band surrounds the groups and is predeterminedly tensioned to clamp together the laminations, and has a predetermined flexibility in a radial direction to form substantially straight bridge sections between the adjacent groups.

Banded electromagnetic stator core

DOEpatents

Fanning, Alan W.; Gonzales, Aaron A.; Patel, Mahadeo R.; Olich, Eugene E.

1996-01-01

A stator core for an electromagnetic pump includes a plurality of circumferentially adjoining groups of flat laminations disposed about a common centerline axis and collectively defining a central bore and a discontinuous outer perimeter, with adjacent groups diverging radially outwardly to form V-shaped gaps. An annular band surrounds the groups and is predeterminedly tensioned to clamp together the laminations, and has a predetermined flexibility in a radial direction to form substantially straight bridge sections between the adjacent groups.

A comparison of experimental and theoretical results for labyrinth gas seals with honeycomb stators. M.S. Thesis

NASA Technical Reports Server (NTRS)

Hawkins, Lawrence Allen

1988-01-01

Experimental results for the rotordynamic stiffness and damping coefficients of a labyrinth -rotor honeycomb-stator seal are presented. The coefficients are compared to the coefficients of a labyrinth-rotor smooth-stator seal having the same geometry. The coefficients are compared to analytical results from a two-control-volume compressible flow model. The experimental results show that the honeycomb stator configuration is more stable than the smooth stator configuration at low rotor speeds. At high rotor speeds and low clearance, the smooth stator seal is more stable. The theoretical model predicts the cross-coupled stiffness of the honeycomb stator seal correctly within 25 percent of measured values. The model provides accurate predictions of direct damping for large clearance seals. Overall, the model does not perform as well for low clearance seals as for high clearance seals.

Ultra-high speed permanent magnet axial gap alternator with multiple stators

DOEpatents

Hawsey, Robert A.; Bailey, J. Milton

1991-01-01

An ultra-high speed, axial gap alternator that can provide an output to a plurality of loads, the alternator providing magnetic isolation such that operating conditions in one load will not affect operating conditions of another load. This improved alternator uses a rotor member disposed between a pair of stator members, with magnets disposed in each of the rotor member surfaces facing the stator members. The magnets in one surface of the rotor member, which alternate in polarity, are isolated from the magnets in the other surface of the rotor member by a disk of magnetic material disposed between the two sets of magents. In the preferred embodiment, this disk of magnetic material is laminated between two layers of non-magnetic material that support the magnets, and the magnetic material has a peripheral rim that extends to both surfaces of the rotor member to enhance the structural integrity. The stator members are substantially conventional in construction in that equally-spaced and radially-oriented slots are provided, and winding members are laid in these slots. A unit with multiple rotor members and stator members is also described.

A piezoelectric ultrasonic linear micromotor using a slotted stator.

PubMed

Yun, Cheol-Ho; Watson, Brett; Friend, James; Yeo, Leslie

2010-08-01

A novel ultrasonic micro linear motor that uses 1st longitudinal and 2nd bending modes, derived from a bartype stator with a rectangular slot cut through the stator length, has been proposed and designed for end-effect devices of microrobotics and bio-medical applications. The slot structure plays an important role in the motor design, and can be used not only to tune the resonance frequency of the two vibration modes but also to reduce the undesirable longitudinal coupling displacement caused by bending vibration at the end of the stator. By using finite element analysis, the optimal slot dimension to improve the driving tip motion was determined, resulting in the improvement of the motor performance. The trial linear motor, with a weight of 1.6 g, gave a maximum driving velocity of 1.12 m/s and a maximum driving force of 3.4 N. A maximum mechanical output power of 1.1 W was obtained at force of 1.63 N and velocity of 0.68 m/s. The output mechanical power per unit weight was 688 W/kg.

Patterns of the Rotor-over-Stator Rolling under Change in the Damping Components

NASA Astrophysics Data System (ADS)

Shatokhin, V. F.

2018-03-01

As experimental studies show, the rubbing of the rotor against the structure usually excites harmonics of different frequencies. In high-frequency regions, the power of the vibration signal appears to be considerable. The rotor—supports—stator system is in an unstable equilibrium state during the contact interaction between the rotor and the stator. The forces exerted on the rotor facilitate the excitation of the asynchronous rolling and its damping. The forces have been determined that facilitate the excitation of the progressive and retrograde rotor precession. The consideration of these forces in the algorithm for modeling the rotor-over-stator rolling development allows investigation of the impact of the components of the above forces on the behavior of the rotor system. The initial excitation—disturbance of the normal operation—of the rotor and subsequent unsteady oscillations of it result from sudden imbalance in the second span. The results of numerical modeling of the rubbing in the second span and the rotor-over-stator rolling upon change in the damping components of secondary (gyroscopic) components b ij ( i ≠ j) of the damping matrix are presented for the rotor on three bearing-supports considering the synergetic effect of the forces of various types exerted on the rotor. It is shown that change in one of the parameters of the excitation forces leads to ambiguity of the pattern (manifestation form) of the asynchronous rotor-over-stator rolling and proves the existence of more than one states towards which the rotor—supports—stator system tends. In addition to the rolling with a constant rotor—stator contact, oscillations of the rotor develop in the direction perpendicular to the common trajectory of the precession motion of the rotor's center with transition to the vibro-impact motion mode. The oscillations of the rotor tend towards the symmetry center of the system (the stator bore center). The reason is the components of the stiffness

Banded electromagnetic stator core

DOEpatents

Fanning, A.W.; Gonzales, A.A.; Patel, M.R.; Olich, E.E.

1996-06-11

A stator core for an electromagnetic pump includes a plurality of circumferentially adjoining groups of flat laminations disposed about a common centerline axis and collectively defining a central bore and a discontinuous outer perimeter, with adjacent groups diverging radially outwardly to form V-shaped gaps. An annular band surrounds the groups and is predeterminedly tensioned to clamp together the laminations, and has a predetermined flexibility in a radial direction to form substantially straight bridge sections between the adjacent groups. 5 figs.

Banded electromagnetic stator core

DOEpatents

Fanning, A.W.; Gonzales, A.A.; Patel, M.R.; Olich, E.E.

1994-04-05

A stator core for an electromagnetic pump includes a plurality of circumferentially adjoining groups of flat laminations disposed about a common centerline axis and collectively defining a central bore and a discontinuous outer perimeter, with adjacent groups diverging radially outwardly to form V-shaped gaps. An annular band surrounds the groups and is predeterminedly tensioned to clamp together the laminations, and has a predetermined flexibility in a radial direction to form substantially straight bridge sections between the adjacent groups. 5 figures.

Epoxy Adhesives for Stator Magnet Assembly in Stirling Radioisotope Generators (SRG)

NASA Technical Reports Server (NTRS)

Cater, George M.

2004-01-01

As NASA seeks to fulfill its goals of exploration and understanding through missions planned to visit the moons of Saturn and beyond, a number of challenges arise from the idea of deep space flight. One of the first problems associated with deep space travel is electrical power production for systems on the spacecraft. Conventional methods such as solar power are not practical because efficiency decreases substantially as the craft moves away from the Sun. The criterion for power generation during deep space missions are very specific, the main points requiring high reliability, low mass, minimal vibration and a long lifespan. A Stirling generator, although fairly old in concept, is considered to be a potential solution for electrical power generation for deep space flight. A Stirling generator works on the same electromagnetic principles of a standard generator, using the linear motion of the alternator through the stationary stator which produces electric induction. The motion of the alternator, however, is produced by the heating and cooling dynamics of pressurized gases. Essentially heating one end and cooling another of a contained gas will cause a periodic expansion and compression of the gas from one side to the other, which a displacer translates into linear mechanical motion. NASA needs to confirm that the materials used in the generator will be able to withstand the rigors of space and the life expectancy of the mission. I am working on the verification of the epoxy adhesives used to bond magnets to the steel lamination stack to complete the stator; in terms of in-service performance and durability under various space environments. Understanding the proper curing conditions, high temperature properties, and degassing problems as well as production difficulties are crucial to the long term success of the generator. system and steel substrate used in the stator. To optimize the curing conditions of the epoxies, modulated differential scanning calorimetry

Laminated electromagnetic pump stator core

DOEpatents

Fanning, Alan W.

1995-01-01

A stator core for an electromagnetic pump includes a plurality of circumferentially abutting tapered laminations extending radially outwardly from a centerline axis to collectively define a radially inner bore and a radially outer circumference. Each of the laminations includes radially inner and outer edges and has a thickness increasing from the inner edge toward the outer edge to provide a substantially continuous path adjacent the circumference.

Magnetically induced rotor vibration in dual-stator permanent magnet motors

NASA Astrophysics Data System (ADS)

Xie, Bang; Wang, Shiyu; Wang, Yaoyao; Zhao, Zhifu; Xiu, Jie

2015-07-01

Magnetically induced vibration is a major concern in permanent magnet (PM) motors, which is especially true for dual-stator motors. This work develops a two-dimensional model of the rotor by using energy method, and employs this model to examine the rigid- and elastic-body vibrations induced by the inner stator tooth passage force and that by the outer. The analytical results imply that there exist three typical vibration modes. Their presence or absence depends on the combination of magnet/slot, force's frequency and amplitude, the relative position between two stators, and other structural parameters. The combination and relative position affect these modes via altering the force phase. The predicted results are verified by magnetic force wave analysis by finite element method (FEM) and comparison with the existing results. Potential directions are also given with the anticipation of bringing forth more interesting and useful findings. As an engineering application, the magnetically induced vibration can be first reduced via the combination and then a suitable relative position.

An electric contact method to measure contact state between stator and rotor in a traveling wave ultrasonic motor.

PubMed

Qu, Jianjun; Zhou, Tieying

2003-09-01

Performances of ultrasonic motor (USM) depend considerably on contact state between stator and rotor. To measure the contact state in a traveling wave ultrasonic motor (TWUSM), a special test method is necessary. This paper develops a new method named electric contact method to measure contact state of stator and rotor in traveling wave type USM. The effects of pre-load and exciting voltage (amplitude) of stator on contact state between stator and rotor are studied with this method. By a simulating tester of friction properties of TWUSM, the variations of stalling torque and no-load speed against the pre-load and the exciting voltage have been measured. The relative contact length that describes the contact characteristic of stator and rotor is proposed. The relation between the properties of TWUSM and the contact state of stator and rotor are presented. Additionally, according to a theoretical contact model of stator and rotor in TWUSM, the contact lengths at given conditions are calculated and compared with the experimental results.

Numerical Simulation of Fluid Flow in a Simple Rotor/Stator Pair

DTIC Science & Technology

1991-06-01

describes a series of numerical experiments dealing with rotor/stator interactions in hydroturbines . The means of analysis was a nonconforming sliding...science and industry is the improvement of the efficiency of the hydroturbine . Numerical flow analysis is essential in order to properly conduct this...evaluation. The hydroturbine is typically modeled as an infinite series of rotor/stator pairs. Figure 1 is an illustration of an axial-flow machine with

Method Of Wire Insertion For Electric Machine Stators

DOEpatents

Brown, David L; Stabel, Gerald R; Lawrence, Robert Anthony

2005-02-08

A method of inserting coils in slots of a stator is provided. The method includes interleaving a first set of first phase windings and a first set of second phase windings on an insertion tool. The method also includes activating the insertion tool to radially insert the first set of first phase windings and the first set of second phase windings in the slots of the stator. In one embodiment, interleaving the first set of first phase windings and the first set of second phase windings on the insertion tool includes forming the first set of first phase windings in first phase openings defined in the insertion tool, and forming the first set of second phase windings in second phase openings defined in the insertion tool.

Predicting broadband noise from a stator vane of a gas turbine engine

NASA Technical Reports Server (NTRS)

Hanson, Donald B. (Inventor)

2002-01-01

A computer-implemented model of fan section of a gas turbine engine accounts for the turbulence in the gas flow emanating from the rotor assembly and impinging upon an inlet to the stator vane cascade. The model allows for user-input variations in the sweep and/or lean angles for the stator vanes. The model determines the resulting acoustic response of the fan section as a function of the turbulence and the lean and/or sweep angles of the vanes. The model may be embodied in software that is rapidly executed in a computer. This way, an optimum arrangement in terms of fan noise reduction is quickly determined for the stator vane lean and sweep physical positioning in the fan section of a gas turbine engine.

Cold-air performance of compressor-drive turbine of Department of Energy upgraded automobile gas turbine engine. 1: Volute-manifold and stator performance

NASA Technical Reports Server (NTRS)

Roelke, R. J.; Haas, J. E.

1981-01-01

The aerodynamic performance of the inlet manifold and stator assembly of the compressor drive turbine was experimentally determined with cold air as the working fluid. The investigation included measurements of mass flow and stator-exit fluid torque as well as radial surveys of total pressure and flow angle at the stator inlet and annulus surveys of total pressure and flow angle at the stator exit. The stator-exit aftermixed flow conditions and overall stator efficiency were obtained and compared with their design values and the experimental results from three other stators. In addition, an analysis was made to determine the constituent aerodynamic losses that made up the stator kinetic energy loss.

Numerical and experimental study of the performance effects of varying vaneless space in high-speed micro turbine stators

NASA Astrophysics Data System (ADS)

Ke, Changlei; Xiong, Lianyou; Peng, Nan; Dong, Bin; Li, Kongrong; Li, Jing; Liu, Liqiang

2017-12-01

In order to make direct performance comparisons of varying the vaneless space in high-speed micro turbomachinery, an extensive experimental and numerical program have been carried out on a 22 mm leading-edge diameter mixed and inward flow radial turbine using a variety of stator designs. The stator was designed using commercial design software, having 9 vanes and the radial clearance (vaneless space) between stator and rotor was 0.5 mm single side, that means the ratio of the stator trailing edge radius to the rotor leading edge radius Rte/rle is 1.0455. Two additional stators (Rte/rle is 1.0182 and 1.0727) were also designed and manufactured. According to the design condition, just like pressure at stator inlet or mass flow rate for all passages, a series of CFD simulations were carried out in order to guide design iterations towards achieving a matched flow capacity for each stator. In this way the variations in the measured stage efficiency could be attributed to the stator passages only, thus allowing direct comparisons to be made. The losses for different radial clearances have been quantified and the variations in the measured and computed efficiency were used to recommend optimum values of Rte/rle.

Compressor Stator Time-Variant Aerodynamic Response to Upstream Rotor Wakes.

DTIC Science & Technology

1976-11-01

periodic varia t i ons in pressure , velocity and flow direction in the exit field of an upstream element , wh i ch appea r as temporall y vary ing in a...compressor features blad i ng (42 rotor blades and 40 stator vanes , NACA 65 F Series ) that is aerodynamicall y l oaded to levels that are typical of...measurements were accom- — p lished by instrumenting a pair of the NACA Series 65 stator — vanes with flush mounted Ku lite thin -line des i gn dynamic

3D Magnetic Field Analysis of a Turbine Generator Stator Core-end Region

NASA Astrophysics Data System (ADS)

Wakui, Shinichi; Takahashi, Kazuhiko; Ide, Kazumasa; Takahashi, Miyoshi; Watanabe, Takashi

In this paper we calculated magnetic flux density and eddy current distributions of a 71MVA turbine generator stator core-end using three-dimensional numerical magnetic field analysis. Subsequently, the magnetic flux densities and eddy current densities in the stator core-end region on the no-load and three-phase short circuit conditions obtained by the analysis have good agreements with the measurements. Furthermore, the differences of eddy current and eddy current loss in the stator core-end region for various load conditions are shown numerically. As a result, the facing had an effect that decrease the eddy current loss of the end plate about 84%.

Multi-mode sliding mode control for precision linear stage based on fixed or floating stator.

PubMed

Fang, Jiwen; Long, Zhili; Wang, Michael Yu; Zhang, Lufan; Dai, Xufei

2016-02-01

This paper presents the control performance of a linear motion stage driven by Voice Coil Motor (VCM). Unlike the conventional VCM, the stator of this VCM is regulated, which means it can be adjusted as a floating-stator or fixed-stator. A Multi-Mode Sliding Mode Control (MMSMC), including a conventional Sliding Mode Control (SMC) and an Integral Sliding Mode Control (ISMC), is designed to control the linear motion stage. The control is switched between SMC and IMSC based on the error threshold. To eliminate the chattering, a smooth function is adopted instead of a signum function. The experimental results with the floating stator show that the positioning accuracy and tracking performance of the linear motion stage are improved with the MMSMC approach.

System and method for monitoring and controlling stator winding temperature in a de-energized AC motor

DOEpatents

Lu, Bin [Kenosha, WI; Luebke, Charles John [Sussex, WI; Habetler, Thomas G [Snellville, GA; Zhang, Pinjia [Atlanta, GA; Becker, Scott K [Oak Creek, WI

2011-12-27

A system and method for measuring and controlling stator winding temperature in an AC motor while idling is disclosed. The system includes a circuit having an input connectable to an AC source and an output connectable to an input terminal of a multi-phase AC motor. The circuit further includes a plurality of switching devices to control current flow and terminal voltages in the multi-phase AC motor and a controller connected to the circuit. The controller is configured to activate the plurality of switching devices to create a DC signal in an output of the motor control device corresponding to an input to the multi-phase AC motor, determine or estimate a stator winding resistance of the multi-phase AC motor based on the DC signal, and estimate a stator temperature from the stator winding resistance. Temperature can then be controlled and regulated by DC injection into the stator windings.

Investigation of a tubular dual-stator flux-switching permanent-magnet linear generator for free-piston energy converter

NASA Astrophysics Data System (ADS)

Sui, Yi; Zheng, Ping; Tong, Chengde; Yu, Bin; Zhu, Shaohong; Zhu, Jianguo

2015-05-01

This paper describes a tubular dual-stator flux-switching permanent-magnet (PM) linear generator for free-piston energy converter. The operating principle, topology, and design considerations of the machine are investigated. Combining the motion characteristic of free-piston Stirling engine, a tubular dual-stator PM linear generator is designed by finite element method. Some major structural parameters, such as the outer and inner radii of the mover, PM thickness, mover tooth width, tooth width of the outer and inner stators, etc., are optimized to improve the machine performances like thrust capability and power density. In comparison with conventional single-stator PM machines like moving-magnet linear machine and flux-switching linear machine, the proposed dual-stator flux-switching PM machine shows advantages in higher mass power density, higher volume power density, and lighter mover.

Reduction of Wake-Stator Interaction Noise Using Passive Porosity

NASA Technical Reports Server (NTRS)

Tinetti, Ana F.; Kelly, Jeffrey J.; Thomas, Russell H.; Bauer, Steven X. S.

2002-01-01

The present study was conducted to assess the potential of Passive Porosity Technology as a mechanism to reduce interaction noise in turbomachinery by reducing the fluctuating forces acting on the vane surfaces. To do so, a typical fan stator airfoil was subjected to the effects of a transversely moving wake; time histories of the primitive aerodynamic variables, obtained from Computational Fluid Dynamics (CFD) solutions, were then input into an acoustic prediction code. This procedure was performed on the solid airfoil to obtain a baseline, and on a series of porous configurations in order to isolate those that yield maximum noise reductions without compromising the aerodynamic performance of the stator. It was found that communication between regions of high pressure differential - made possible by the use of passive porosity - is necessary to significantly alter the noise radiation pattern of the stator airfoil. In general, noise reductions were obtained for those configurations incorporating passive porosity in the region between x/c is approximately 0.15 on the suction side of the airfoil and x/c is approximately 0.20 on the pressure side. Reductions in overall radiated noise of approximately 1.0 dB were obtained. The noise benefit increased to about 2.5 dB when the effects of loading noise alone were considered.

Laminated electromagnetic pump stator core

DOEpatents

Fanning, A.W.

1995-08-08

A stator core for an electromagnetic pump includes a plurality of circumferentially abutting tapered laminations extending radially outwardly from a centerline axis to collectively define a radially inner bore and a radially outer circumference. Each of the laminations includes radially inner and outer edges and has a thickness increasing from the inner edge toward the outer edge to provide a substantially continuous path adjacent the circumference. This pump is used in nuclear fission reactors. 19 figs.

A finite volume method and experimental study of a stator of a piezoelectric traveling wave rotary ultrasonic motor.

PubMed

Bolborici, V; Dawson, F P; Pugh, M C

2014-03-01

Piezoelectric traveling wave rotary ultrasonic motors are motors that generate torque by using the friction force between a piezoelectric composite ring (or disk-shaped stator) and a metallic ring (or disk-shaped rotor) when a traveling wave is excited in the stator. The motor speed is proportional to the amplitude of the traveling wave and, in order to obtain large amplitudes, the stator is excited at frequencies close to its resonance frequency. This paper presents a non-empirical partial differential equations model for the stator, which is discretized using the finite volume method. The fundamental frequency of the discretized model is computed and compared to the experimentally-measured operating frequency of the stator of Shinsei USR60 piezoelectric motor. Copyright © 2013 Elsevier B.V. All rights reserved.

Influence of vane sweep on rotor-stator interaction noise

NASA Technical Reports Server (NTRS)

Envia, Edmane; Kerschen, Edward J.

1990-01-01

The influence of vane sweep in rotor-stator interaction noise is investigated. In an analytical approach, the interaction of a convected gust representing the rotor viscous wake, with a cascade of cascade of finite span swept airfoils, representing the stator, is analyzed. The analysis is based on the solution of the exact linearized equations of motion. High frequency convected gusts for which noise generation is concentrated near the leading edge of airfoils is considered. In a preliminary study, the problem of an isolated finite span swept airfoil interacting with a convected gust is analyzed. Results indicate that sweep can substantially reduce the farfield noise levels for a single airfoil. Using the single airfoil model, an approximate solution to the problem of noise radiation from a cascade of finite span swept airfoils interacting with a convected gust is derived. A parametric study of noise generated by gust cascade interaction is carried out to assess the effectiveness of vane sweep in reducing rotor-stator interaction noise. The results show that sweep is beneficial in reducing noise levels. Rotor wake twist or circumferential lean substantially influences the effectiveness of vane sweep. The orientation of vane sweep must be chosen to enhance the natural phase lag caused by wake lean, in which case rather small sweep angles substantially reduce the noise levels.

Influence of vane sweep on rotor-stator interaction noise

NASA Astrophysics Data System (ADS)

Envia, Edmane; Kerschen, Edward J.

1990-12-01

The influence of vane sweep in rotor-stator interaction noise is investigated. In an analytical approach, the interaction of a convected gust representing the rotor viscous wake, with a cascade of cascade of finite span swept airfoils, representing the stator, is analyzed. The analysis is based on the solution of the exact linearized equations of motion. High frequency convected gusts for which noise generation is concentrated near the leading edge of airfoils is considered. In a preliminary study, the problem of an isolated finite span swept airfoil interacting with a convected gust is analyzed. Results indicate that sweep can substantially reduce the farfield noise levels for a single airfoil. Using the single airfoil model, an approximate solution to the problem of noise radiation from a cascade of finite span swept airfoils interacting with a convected gust is derived. A parametric study of noise generated by gust cascade interaction is carried out to assess the effectiveness of vane sweep in reducing rotor-stator interaction noise. The results show that sweep is beneficial in reducing noise levels. Rotor wake twist or circumferential lean substantially influences the effectiveness of vane sweep. The orientation of vane sweep must be chosen to enhance the natural phase lag caused by wake lean, in which case rather small sweep angles substantially reduce the noise levels.

Two-stage fan. 4: Performance data for stator setting angle optimization

NASA Technical Reports Server (NTRS)

Burger, G. D.; Keenan, M. J.

1975-01-01

Stator setting angle optimization tests were conducted on a two-stage fan to improve efficiency at overspeed, stall margin at design speed, and both efficiency and stall margin at partspeed. The fan has a design pressure ratio of 2.8, a flow rate of 184.2 lb/sec (83.55 kg/sec) and a 1st-stage rotor tip speed of 1450 ft/sec (441.96 in/sec). Performance was obtained at 70,100, and 105 percent of design speed with different combinations of 1st-stage and 2nd-stage stator settings. One combination of settings, other than design, was common to all three speeds. At design speed, a 2.0 percentage point increase in stall margin was obtained at the expense of a 1.3 percentage point efficiency decrease. At 105 percent speed, efficiency was improved by 1.8 percentage points but stall margin decreased 4.7 percentage points. At 70 percent speed, no change in stall margin or operating line efficiency was obtained with stator resets although considerable speed-flow requlation occurred.

Windage Heating in a Shrouded Rotor-Stator System.

PubMed

Tao, Zhi; Zhang, Da; Luo, Xiang; Xu, Guoqiang; Han, Jianqiao

2014-06-01

This paper has experimentally and numerically studied the windage heating in a shrouded rotor-stator disk system with superimposed flow. Temperature rise in the radius direction on the rotating disk is linked to the viscous heating process when cooling air flows through the rotating component. A test rig has been developed to investigate the effect of flow parameters and the gap ratio on the windage heating, respectively. Experimental results were obtained from a 0.45 m diameter disk rotating at up to 12,000 rpm with gap ratio varying from 0.02 to 0.18 and a stator of the same diameter. Infrared temperature measurement technology has been proposed to measure the temperature rise on the rotor surface directly. The PIV technique was adapted to allow for tangential velocity measurements. The tangential velocity data along the radial direction in the cavity was compared with the results obtained by CFD simulation. The comparison between the free disk temperature rise data and an associated theoretical analysis for the windage heating indicates that the adiabatic disk temperature can be measured by infrared method accurately. For the small value of turbulence parameter, the gap ratio has limited influence on the temperature rise distribution along the radius. As turbulence parameter increases, the temperature rise difference is independent of the gap ratio, leaving that as a function of rotational Reynolds number and throughflow Reynolds number only. The PIV results show that the swirl ratio of the rotating core between the rotor and the stator has a key influence on the windage heating.

Electromagnetic pump stator coil

DOEpatents

Fanning, A.W.; Dahl, L.R.

1996-06-25

An electrical stator coil for an electromagnetic pump includes a continuous conductor strip having first and second terminals at opposite ends thereof and an intermediate section disposed therebetween. The strip is configured in first and second coil halves, with the first coil half including a plurality of windings extending from the first terminal to the intermediate section, and the second coil half including a plurality of windings extending from the second terminal to the intermediate section. The first and second coil halves are disposed coaxially, and the first and second terminals are disposed radially inwardly therefrom with the intermediate section being disposed radially outwardly therefrom. 9 figs.

Electromagnetic pump stator coil

DOEpatents

Fanning, Alan W.; Dahl, Leslie R.

1996-01-01

An electrical stator coil for an electromagnetic pump includes a continuous conductor strip having first and second terminals at opposite ends thereof and an intermediate section disposed therebetween. The strip is configured in first and second coil halves, with the first coil half including a plurality of windings extending from the first terminal to the intermediate section, and the second coil half including a plurality of windings extending from the second terminal to the intermediate section. The first and second coil halves are disposed coaxially, and the first and second terminals are disposed radially inwardly therefrom with the intermediate section being disposed radially outwardly therefrom.

A Parametric Study of Unsteady Rotor-Stator Interaction in a Simplified Francis Turbine

NASA Astrophysics Data System (ADS)

Wouden, Alex; Cimbala, John; Lewis, Bryan

2011-11-01

CFD analysis is becoming a critical stage in the design of hydroturbines. However, its capability to represent unsteady flow interactions between the rotor and stator (which requires a 360-degree, mesh-refined model of the turbine passage) is hindered. For CFD to become a more effective tool in predicting the performance of a hydroturbine, the key interactions between the rotor and stator need to be understood using current numerical methods. As a first step towards evaluating this unsteady behavior without the burden of a computationally expensive domain, the stator and Francis-type rotor blades are reduced to flat plates. Local and global variables are compared using periodic, semi-periodic, and 360-degree geometric models and various turbulence models (k-omega, k-epsilon, and Spalart-Allmaras). The computations take place within the OpenFOAM® environment and utilize a general grid interface (GGI) between the rotor and stator computational domains. The rotor computational domain is capable of dynamic rotation. The results demonstrate some of the strengths and limitations of utilizing CFD for hydroturbine analysis. These case studies will also serve as tutorials to help others learn how to use CFD for turbomachinery. This research is funded by a grant from the DOE.

Simulation of unsteady flows through stator and rotor blades of a gas turbine using the Chimera method

NASA Technical Reports Server (NTRS)

Nakamura, S.; Scott, J. N.

1993-01-01

A two-dimensional model to solve compressible Navier-Stokes equations for the flow through stator and rotor blades of a turbine is developed. The flow domains for the stator and rotor blades are coupled by the Chimera method that makes grid generation easy and enhances accuracy because the area of the grid that have high turning of grid lines or high skewness can be eliminated from the computational domain after the grids are generated. The results of flow computations show various important features of unsteady flows including the acoustic waves interacting with boundary layers, Karman vortex shedding from the trailing edge of the stator blades, pulsating incoming flow to a rotor blade from passing stator blades, and flow separation from both suction and pressure sides of the rotor blades.

Mean velocity and decay characteristics of the guidevane and stator blade wake of an axial flow compressor

NASA Technical Reports Server (NTRS)

Lakshminarayana, B.; Davino, R.

1979-01-01

Pure tone noise, blade row vibrations, and aerodynamic losses are phenomena which are influenced by stator and IGV (inlet guide vane) blade wake production, decay, and interaction in an axial-flow compressor. The objective of this investigation is to develop a better understanding of the nature of stator and IGV blade wakes that are influenced by the presence of centrifugal forces due to flow curvature. A single sensor hot wire probe was employed to determine the three mean velocity components of stator and IGV wakes of a single stage compressor. These wake profiles indicated a varying decay rate of the tangential and axial wake velocity components and a wake profile similarity. An analysis, which predicts this trend, has been developed. The radial velocities are found to be appreciable in both IGV and the stator wakes.

A Way to Select Electrical Sheets of the Segment Stator Core Motors.

NASA Astrophysics Data System (ADS)

Enomoto, Yuji; Kitamura, Masashi; Sakai, Toshihiko; Ohara, Kouichiro

The segment stator core, high density winding coil, high-energy-product permanent magnet are indispensable technologies in the development of a compact and also high efficient motors. The conventional design method for the segment stator core mostly depended on experienced knowledge of selecting a suitable electromagnetic material, far from optimized design. Therefore, we have developed a novel design method in the selection of a suitable electromagnetic material based on the correlation evaluation between the material characteristics and motor performance. It enables the selection of suitable electromagnetic material that will meet the motor specification.

Kilowatt Isotope Power System: component test report for the Ground Demonstration System Alternator Stator

DOE Office of Scientific and Technical Information (OSTI.GOV)

Brainard, E.L.

1978-04-25

Results are presented of acceptance tests conducted on the Alternator Stator, S/N 002, for the Kilowatt Isotope Power System. These results show that the Alternator Stator, S/N 002 for the Kilowatt Isotope Power System has satisfactorily completed the testing set forth within Sundstrand Test Specification 2538. Test requirements of TS 2538 were extracted from the Kilowatt Isotope Power System, and Phase I Test Plan.

Investigations on bending-torsional vibrations of rotor during rotor-stator rub using Lagrange multiplier method

NASA Astrophysics Data System (ADS)

Mokhtar, Md Asjad; Kamalakar Darpe, Ashish; Gupta, Kshitij

2017-08-01

The ever-increasing need of highly efficient rotating machinery causes reduction in the clearance between rotating and non-rotating parts and increase in the chances of interaction between these parts. The rotor-stator contact, known as rub, has always been recognized as one of the potential causes of rotor system malfunctions and a source of secondary failures. It is one of few causes that influence both lateral and torsional vibrations. In this paper, the rotor stator interaction phenomenon is investigated in the finite element framework using Lagrange multiplier based contact mechanics approach. The stator is modelled as a beam that can respond to axial penetration and lateral friction force during the contact with the rotor. It ensures dynamic stator contact boundary and more realistic contact conditions in contrast to most of the earlier approaches. The rotor bending-torsional mode coupling during contact is considered and the vibration response in bending and torsion are analysed. The effect of parameters such as clearance, friction coefficient and stator stiffness are studied at various operating speeds and it has been found that certain parameter values generate peculiar rub related features. Presence of sub-harmonics in the lateral vibration frequency spectra are prominently observed when the rotor operates near the integer multiple of its lateral critical speed. The spectrum cascade of torsional vibration shows the presence of bending critical speed along with the larger amplitudes of frequencies close to torsional natural frequency of the rotor. When m × 1/n X frequency component of rotational frequency comes closer to the torsional natural frequency, stronger torsional vibration amplitude is noticed in the spectrum cascade. The combined information from the stator vibration and rotor lateral-torsional vibration spectral features is proposed for robust rub identification.

Speed of the bacterial flagellar motor near zero load depends on the number of stator units.

PubMed

Nord, Ashley L; Sowa, Yoshiyuki; Steel, Bradley C; Lo, Chien-Jung; Berry, Richard M

2017-10-31

The bacterial flagellar motor (BFM) rotates hundreds of times per second to propel bacteria driven by an electrochemical ion gradient. The motor consists of a rotor 50 nm in diameter surrounded by up to 11 ion-conducting stator units, which exchange between motors and a membrane-bound pool. Measurements of the torque-speed relationship guide the development of models of the motor mechanism. In contrast to previous reports that speed near zero torque is independent of the number of stator units, we observe multiple speeds that we attribute to different numbers of units near zero torque in both Na + - and H + -driven motors. We measure the full torque-speed relationship of one and two H + units in Escherichia coli by selecting the number of H + units and controlling the number of Na + units in hybrid motors. These experiments confirm that speed near zero torque in H + -driven motors increases with the stator number. We also measured 75 torque-speed curves for Na + -driven chimeric motors at different ion-motive force and stator number. Torque and speed were proportional to ion-motive force and number of stator units at all loads, allowing all 77 measured torque-speed curves to be collapsed onto a single curve by simple rescaling. Published under the PNAS license.

Speed of the bacterial flagellar motor near zero load depends on the number of stator units

PubMed Central

Nord, Ashley L.; Sowa, Yoshiyuki; Steel, Bradley C.; Lo, Chien-Jung; Berry, Richard M.

2017-01-01

The bacterial flagellar motor (BFM) rotates hundreds of times per second to propel bacteria driven by an electrochemical ion gradient. The motor consists of a rotor 50 nm in diameter surrounded by up to 11 ion-conducting stator units, which exchange between motors and a membrane-bound pool. Measurements of the torque–speed relationship guide the development of models of the motor mechanism. In contrast to previous reports that speed near zero torque is independent of the number of stator units, we observe multiple speeds that we attribute to different numbers of units near zero torque in both Na+- and H+-driven motors. We measure the full torque–speed relationship of one and two H+ units in Escherichia coli by selecting the number of H+ units and controlling the number of Na+ units in hybrid motors. These experiments confirm that speed near zero torque in H+-driven motors increases with the stator number. We also measured 75 torque–speed curves for Na+-driven chimeric motors at different ion-motive force and stator number. Torque and speed were proportional to ion-motive force and number of stator units at all loads, allowing all 77 measured torque–speed curves to be collapsed onto a single curve by simple rescaling. PMID:29078322

Electromagnetic pump stator frame having power crossover struts

DOEpatents

Fanning, Alan W.; Olich, Eugene E.

1995-01-01

A stator frame for an electromagnetic pump includes a casing joined to a hub by a plurality of circumferentially spaced apart struts. At least one electrically insulated power crossover lead extends through the hub, through a crossover one of the struts, and through the casing for carrying electrical current therethrough.

Three-dimensional Navier-Stokes simulations of turbine rotor-stator interaction

NASA Technical Reports Server (NTRS)

Rai, Man Mohan

1988-01-01

Fluid flows within turbomachinery tend to be extremely complex in nature. Understanding such flows is crucial to improving current designs of turbomachinery. The computational approach can be used to great advantage in understanding flows in turbomachinery. A finite difference, unsteady, thin layer, Navier-Stokes approach to calculating the flow within an axial turbine stage is presented. The relative motion between the stator and rotor airfoils is made possible with the use of patched grids that move relative to each other. The calculation includes endwall and tip leakage effects. An introduction to the rotor-stator problem and sample results in the form of time averaged surface pressures are presented. The numerical data are compared with experimental data and the agreement between the two is found to be good.

Rotor and stator assembly configured as an aspirating face seal

NASA Technical Reports Server (NTRS)

Turnquist, Norman Arnold (Inventor); Bagepalli, Bharat Sampathkumaran (Inventor); Reluzco, George (Inventor); Tseng, Wu-Yang (Inventor)

1999-01-01

A rotor and stator assembly having a rotor and a stator with opposing surfaces defining an air bearing and an air dam of an aspirating face seal. In a first embodiment, the air bearing and the air dam are axially offset. In a second embodiment, the rotor has an axially extending protuberance located radially between the air bearing and the air dam. The axial offset and the protuberance each act to divert the air flow (e.g., compressed gas or combustion gases in a gas turbine or steam in a steam turbine) in a direction transverse to the air flow direction through the air bearing and the air dam, thus isolating the air flows from the air bearing and the air dam which improves seal performance.

Dual stator winding variable speed asynchronous generator: optimal design and experiments

NASA Astrophysics Data System (ADS)

Tutelea, L. N.; Deaconu, S. I.; Popa, G. N.

2015-06-01

In the present paper is carried out a theoretical and experimental study of dual stator winding squirrel cage asynchronous generator (DSWA) behavior in the presence of saturation regime (non-sinusoidal) due to the variable speed operation. The main aims are the determination of the relations of calculating the equivalent parameters of the machine windings to optimal design using a Matlab code. Issue is limited to three phase range of double stator winding cage-induction generator of small sized powers, the most currently used in the small adjustable speed wind or hydro power plants. The tests were carried out using three-phase asynchronous generator having rated power of 6 [kVA].

A study of generator performance with linear permanent magnet in various coil configuration and rotor-stator geometry

NASA Astrophysics Data System (ADS)

Asy'ari, Hasyim; Sarjito, Prasetio, Septian Heri

2017-04-01

The aim of the research work describe in this paper was to design and optimize a permanent magnet linear generator for renewable energy power plants. It is cover of first stage of designing stator and rotor permanent magnet linear generator. Stator design involves determining dimensions, number of slots, diameter of wire, and the number of winding in each slot. The design of the rotor includes rotor manufacture of PVC pipe material, 10 pieces of permanent magnet type ferrite 271 mikroweber, and resin. The second stage was to assemble the stator and rotor that has been done in the first stage to be a permanent magnet linear generator. The third stage was to install a permanent magnet linear generator with induction motors. Further stage was to test performance of a permanent magnet linear generator by utilizing of induction motor as a prime mover experimentally. In this study, permanent magnet linear generator with a rotor consists of five pairs of permanent magnets. The stator consists of 6 slots of the stator frame, each slot mounted stator coil of 200, 300, 400, 500, and 800 windings, and dimensions of wire used was 0.4 mm. The stator frame was made from acrylic. Results of the experiment that, permanent magnet linear generator when no load was able to generate a DC voltage of 14.5 volts at 300 rpm, and at the output of the linear generator when it is connected to the DC fan as a load only generated of 6.7 volts. It concludes that permanent magnet linear generator output can be used as an input device hybrid system. Data obtained from this experiment in laboratory scale can be developed in a larger scale by varying the type of magnet being used, the number of windings, and the speed used to generate more power.

Transonic Axial Splittered Rotor Tandem Stator Stage

DTIC Science & Technology

2016-12-01

CODE 13. ABSTRACT (maximum 200 words) Development of a procedure to model the hot shape of a rotor blade and a comparison analysis of the transonic...fluid-structure interaction. Rotational forces as well as gas loading forces were observed as an influence on blade deformation. Utilizing the...Turbomachinery, splittered rotor, tandem stator, transonic compressor, blade deformation, fluid-structure interaction 15. NUMBER OF PAGES 87 16. PRICE

Unsteady Loss in the Stator Due to the Incoming Rotor Wake in a Highly-Loaded Transonic Compressor

NASA Technical Reports Server (NTRS)

Hah, Chunill

2015-01-01

The present paper reports an investigation of unsteady loss generation in the stator due to the incoming rotor wake in an advanced GE transonic compressor design with a high-fidelity numerical method. This advanced compressor with high reaction and high stage loading has been investigated both experimentally and analytically in the past. The measured efficiency in this advanced compressor is significantly lower than the design intention/goal. The general understanding is that the current generation of compressor design/analysis tools miss some important flow physics in this modern compressor design. To pinpoint the source of the efficiency miss, an advanced test with a detailed flow traverse was performed for the front one and a half stage at the NASA Glenn Research Center. Detailed data-match analysis by GE identified an unexpected high loss generation in the pressure side of the stator passage. Higher total temperature and lower total pressure are measured near the pressure side of the stator. Various analyses based on the RANS and URANS of the compressor stage do not calculate the measured higher total temperature and lower total pressure on the pressure side of the stator. In the present paper, a Large Eddy Simulation (LES) is applied to find the fundamental mechanism of this unsteady loss generation in the stator due to the incoming rotor wake. The results from the LES were first compared with the NASA test results and the GE interpretation of the test data. LES calculates lower total pressure and higher total temperature on the pressure side of the stator, as the measured data showed, resulting in large loss generation on the pressure side of the stator. Detailed examination of the unsteady flow field from LES shows that the rotor wake, which has higher total temperature and higher total pressure relative to the free stream, interacts quite differently with the pressure side of the blade compared to the suction side of the blade. The higher temperature in the

Travelling wave ultrasonic motors, Part I: Working principle and mathematical modelling of the stator

NASA Astrophysics Data System (ADS)

Hagedorn, P.; Wallaschek, J.

1992-05-01

Travelling wave ultrasonic motors have recently been attracting considerable attention: they may possibly soon replace—at least in certain areas—small electromagnetic motors. This development has been made possible by recent advances in power electronics, material research and digital control, which allow utilization of the piezoelectric effect for low power motors. In these motors the mechanical energy is generated with frequencies of the order of 40 kHz via piezo-elements producing bending waves in a stator, which has approximately the form of a circular plate. The rotor is then driven by the stator via contact forces, and with an extremely simple mechanism frequency reductions of 1:40 000 and more are obtained between the stator vibration and the rotor motion. As a consequence, one can work in the 40 kHz range on the electrical side, while a low frequency rotation is obtained on the mechanical side, as is desirable for many applications. In the present paper, which is the first of a series, the working principle of travelling wave ultrasonic motors is reviewed, and the main phenomena are mathematically modelled. In further papers a detailed mathematical description of the stator vibration and a first model of the contact problem will be given.

A new traveling wave ultrasonic motor using thick ring stator with nested PZT excitation.

PubMed

Chen, Weishan; Shi, Shengjun; Liu, Yingxiang; Li, Pei

2010-05-01

To avoid the disadvantages of conventional traveling wave ultrasonic motors--lower efficiency PZT working mode of d(31), fragility of the PZT element under strong excitation, fatigue of the adhesive layer under harsh environmental conditions, and low volume of the PZT material in the stator--a new type of traveling wave ultrasonic motor is presented in this paper. Here we implement the stator by nesting 64 PZT stacks in 64 slots specifically cut in a thick metal ring and 64 block springs nested within another 64 slots to produce preloading on the PZT stacks. In this new design, the d33 mode of the PZT is used to excite the flexural vibrations of the stator, and fragility of the PZT ceramics and fatigue of the adhesive layer are no longer an issue. The working principle, FEM simulation, fabrication, and performance measurements of a prototype motor were demonstrated to validate the proposed ideas. Typical output of the prototype motor is no-load speed of 15 rpm and maximum torque of 7.96 N x m. Further improvement will potentially enhance its features by increasing the accuracy in fabrication and adopting appropriate frictional material into the interface between the stator and the rotor.

Diverse high-torque bacterial flagellar motors assemble wider stator rings using a conserved protein scaffold

PubMed Central

Ribardo, Deborah A.; Brennan, Caitlin A.; Ruby, Edward G.; Jensen, Grant J.; Hendrixson, David R.

2016-01-01

Although it is known that diverse bacterial flagellar motors produce different torques, the mechanism underlying torque variation is unknown. To understand this difference better, we combined genetic analyses with electron cryo-tomography subtomogram averaging to determine in situ structures of flagellar motors that produce different torques, from Campylobacter and Vibrio species. For the first time, to our knowledge, our results unambiguously locate the torque-generating stator complexes and show that diverse high-torque motors use variants of an ancestrally related family of structures to scaffold incorporation of additional stator complexes at wider radii from the axial driveshaft than in the model enteric motor. We identify the protein components of these additional scaffold structures and elucidate their sequential assembly, demonstrating that they are required for stator-complex incorporation. These proteins are widespread, suggesting that different bacteria have tailored torques to specific environments by scaffolding alternative stator placement and number. Our results quantitatively account for different motor torques, complete the assignment of the locations of the major flagellar components, and provide crucial constraints for understanding mechanisms of torque generation and the evolution of multiprotein complexes. PMID:26976588

A traveling wave ultrasonic motor with a metal/polymer-matrix material compound stator

NASA Astrophysics Data System (ADS)

Li, Jinbang; Liu, Shuo; Zhou, Ningning; Yu, Aibing; Cui, Yuguo; Chen, Pengfei

2018-01-01

This study proposes a traveling wave ultrasonic motor with a metal/polymer-matrix material compound stator. The stator is composed of a metal ring and polymer-matrix teeth. The resonance frequency of the stator with different structural dimensions was analyzed by the finite element method. From the results, the structure parameters of the metal ring were obtained. The effects of the density and elastic modulus of the tooth material on the resonance frequency were also investigated. A viscoelastic contact model was built to explore the contact state between the compound stator and rotor. Considering the density, elastic modulus and tribological properties, the tooth material was prepared by a molding process. The load-torque and efficiency-torque characteristics of the motor with different tooth thicknesses were measured under different preloads using a preload controlled ultrasonic motor test device. The maximum no-load speed of the motor was about 85 r min-1 with a tooth thickness of 3 mm and a preload of 100 N, the maximum stall torque of the motor was about 0.5 N · m with a tooth thickness of 4 mm and a preload of 125 N, and a maximum efficiency of about 5.5% occurred with a tooth thickness of 4 mm, a preload of 100 N and a torque of 0.3 N · m. The main merits of the proposed ultrasonic motor are low cost, light weight, high processing efficiency and long life.

A Novel Numerical Approach for Generation and Propagation of Rotor-Stator Interaction Noise

NASA Astrophysics Data System (ADS)

Patel, Krishna

As turbofan engine designs move towards bypass ratios ≥12 and corresponding low pressure ratios, fan rotor blade tip Mach numbers are reduced, leading to rotor-stator interaction becoming an important contributor to tonal fan noise. For future aircraft configurations employing boundary layer ingestion, non-uniform flow enters the fan. The impact of such non-uniform flows on the generation and propagation of rotor-stator interaction tones has yet to be assessed. In this thesis, a novel approach is proposed to numerically predict the generation and propagation of rotor-stator interaction noise with distorted inflow. The approach enables a 42% reduction in computational cost compared to traditional approaches employing a sliding interface between the rotor and stator. Such an interface may distort rotor wakes and can cause non-physical acoustic wave reflections if time steps are not sufficiently small. Computational costs are reduced by modelling the rotor using distributed, volumetric body forces. This eliminates the need for a sliding interface and thus allows a larger time step size. The force model responds to local flow conditions and thus can capture the effects of long-wavelength flow distortions. Since interaction noise is generated by the incidence of the rotor wakes onto the stator vanes, the key challenge is to produce the wakes using a body force field since the rotor blades are not directly modelled. It is shown that such an approach can produce wakes by concentrating the viscous forces along streamtubes in the last 15% chord. The new approach to rotor wake generation is assessed on the GE R4 fan from NASA's Source Diagnostic Test, for which the computed overall aerodynamic performance matches the experiment to within 1%. The rotor blade wakes are generated with widths in excellent agreement and depths in fair agreement with the experiment. An assessment of modal sound power levels computed in the exhaust duct indicates that this approach can be used

Performance of a high-work, low-aspect-ratio turbine stator tested with a realistic inlet radial temperature gradient

NASA Technical Reports Server (NTRS)

Stabe, Roy G.; Schwab, John R.

1991-01-01

A 0.767-scale model of a turbine stator designed for the core of a high-bypass-ratio aircraft engine was tested with uniform inlet conditions and with an inlet radial temperature profile simulating engine conditions. The principal measurements were radial and circumferential surveys of stator-exit total temperature, total pressure, and flow angle. The stator-exit flow field was also computed by using a three-dimensional Navier-Stokes solver. Other than temperature, there were no apparent differences in performance due to the inlet conditions. The computed results compared quite well with the experimental results.

Extension of Useful Operating Range of Axial-Flow Compressors by Use of Adjustable Stator Blades

DTIC Science & Technology

1948-01-01

wmprcssor. AIRCRAFT ENGINE RESEARCH LABORATORY, NATIONAL ADVISORY COMMITTEE FOR AERONAUTICS , CLEVELAND, OHIO, December%9, 1944. APPENDIX A ENTRANCE...ADVISORYCOMbl_E FOR AERONAUTICS either stator blades m rotor bIades can be prevented by the adjustment of the proper row of stator blades : in the first...section, Reynokls number, solidity, blade -a@e setting, and degree of turbulence. Experiments on- airfoil cascades with retarded flow (reference 6, p. 75, and

Acoustic Scattering by Three-Dimensional Stators and Rotors Using the SOURCE3D Code. Volume 1; Analysis and Results

NASA Technical Reports Server (NTRS)

Meyer, Harold D.

1999-01-01

This report provides a study of rotor and stator scattering using the SOURCE3D Rotor Wake/Stator Interaction Code. SOURCE3D is a quasi-three-dimensional computer program that uses three-dimensional acoustics and two-dimensional cascade load response theory to calculate rotor and stator modal reflection and transmission (scattering) coefficients. SOURCE3D is at the core of the TFaNS (Theoretical Fan Noise Design/Prediction System), developed for NASA, which provides complete fully coupled (inlet, rotor, stator, exit) noise solutions for turbofan engines. The reason for studying scattering is that we must first understand the behavior of the individual scattering coefficients provided by SOURCE3D, before eventually understanding the more complicated predictions from TFaNS. To study scattering, we have derived a large number of scattering curves for vane and blade rows. The curves are plots of output wave power divided by input wave power (in dB units) versus vane/blade ratio. Some of these plots are shown in this report. All of the plots are provided in a separate volume. To assist in understanding the plots, formulas have been derived for special vane/blade ratios for which wavefronts are either parallel or normal to rotor or stator chords. From the plots, we have found that, for the most part, there was strong transmission and weak reflection over most of the vane/blade ratio range for the stator. For the rotor, there was little transmission loss.

LES of a ducted propeller with rotor and stator in crashback

NASA Astrophysics Data System (ADS)

Jang, Hyunchul; Mahesh, Krishnan

2012-11-01

A sliding interface method is developed for large eddy simulation (LES) of flow past ducted propellers with both rotor and stator. The method is developed for arbitrarily shaped unstructured elements on massively parallel computing platforms. Novel algorithms for searching sliding elements, interpolation at the sliding interface, and data structures for message passing are developed. We perform LES of flow past a ducted propeller with stator blades in the crashback mode of operation, where a marine vessel is quickly decelerated by rotating the propeller in reverse. The unsteady loads predicted by LES are in good agreement with experiments. A highly unsteady vortex ring is observed outside the duct. High pressure fluctuations are observed near the blade tips, which significantly contribute to the side-force. This work is supported by the United States Office of Naval Research.

Isogeometric analysis and harmonic stator-rotor coupling for simulating electric machines

NASA Astrophysics Data System (ADS)

Bontinck, Zeger; Corno, Jacopo; Schöps, Sebastian; De Gersem, Herbert

2018-06-01

This work proposes Isogeometric Analysis as an alternative to classical finite elements for simulating electric machines. Through the spline-based Isogeometric discretization it is possible to parametrize the circular arcs exactly, thereby avoiding any geometrical error in the representation of the air gap where a high accuracy is mandatory. To increase the generality of the method, and to allow rotation, the rotor and the stator computational domains are constructed independently as multipatch entities. The two subdomains are then coupled using harmonic basis functions at the interface which gives rise to a saddle-point problem. The properties of Isogeometric Analysis combined with harmonic stator-rotor coupling are presented. The results and performance of the new approach are compared to the ones for a classical finite element method using a permanent magnet synchronous machine as an example.

Unsteady Flows in a Single-Stage Transonic Axial-Flow Fan Stator Row. Ph.D. Thesis - Iowa State Univ.

NASA Technical Reports Server (NTRS)

Hathaway, Michael D.

1986-01-01

Measurements of the unsteady velocity field within the stator row of a transonic axial-flow fan were acquired using a laser anemometer. Measurements were obtained on axisymmetric surfaces located at 10 and 50 percent span from the shroud, with the fan operating at maximum efficiency at design speed. The ensemble-average and variance of the measured velocities are used to identify rotor-wake-generated (deterministic) unsteadiness and turbulence, respectively. Correlations of both deterministic and turbulent velocity fluctuations provide information on the characteristics of unsteady interactions within the stator row. These correlations are derived from the Navier-Stokes equation in a manner similar to deriving the Reynolds stress terms, whereby various averaging operators are used to average the aperiodic, deterministic, and turbulent velocity fluctuations which are known to be present in multistage turbomachines. The correlations of deterministic and turbulent velocity fluctuations throughout the axial fan stator row are presented. In particular, amplification and attenuation of both types of unsteadiness are shown to occur within the stator blade passage.

Minimization of torque ripple in ferrite-assisted synchronous reluctance motors by using asymmetric stator

NASA Astrophysics Data System (ADS)

Xu, Meimei; Liu, Guohai; Zhao, Wenxiang; Aamir, Nazir

2018-05-01

Torque ripple is one of the important issues for ferrite assisted synchronous reluctance motors (FASRMs). In this paper, an asymmetrical stator is proposed for the FASRM to reduce its torque ripple. In the proposed FASRM, an asymmetrical stator is designed by appropriately choosing the angle of the slot-opening shift. Meanwhile, its analytical torque expressions are derived. The results show that the proposed FASRM has an effective reduction in the cogging torque, reluctance torque ripple and total torque ripple. Moreover, it is easy to implement while the average torque is not sacrificed.

Nickel base alloy. [for gas turbine engine stator vanes

NASA Technical Reports Server (NTRS)

Freche, J. C.; Waters, W. J. (Inventor)

1977-01-01

A nickel base superalloy for use at temperatures of 2000 F (1095 C) to 2200 F (1205 C) was developed for use as stator vane material in advanced gas turbine engines. The alloy has a nominal composition in weight percent of 16 tungsten, 7 aluminum, 1 molybdenum, 2 columbium, 0.3 zirconium, 0.2 carbon and the balance nickel.

The Application of Surface Potential Test on Hand-making Insulation for Generator Stator End-winding

NASA Astrophysics Data System (ADS)

Lu, Zhu-mao; Liu, Qing; Wang, Tian-zheng; Bai, Lu; Li, Yan-peng

2017-05-01

This paper presents the advantage of surface potential test on hand-making insulation for generator stator end-winding insulation detection, compared with DC or AC withstand voltage test, also details the test principle, connection method and test notes. And through the case, surface potential test on hand-making insulation proved effective for insulation quality detection after generator stator end-winding maintenance, and the experimental data is useful and reliable for the electrical equipment operation and maintenance in the power plant.

System and method for determining stator winding resistance in an AC motor

DOEpatents

Lu, Bin [Kenosha, WI; Habetler, Thomas G [Snellville, GA; Zhang, Pinjia [Atlanta, GA; Theisen, Peter J [West Bend, WI

2011-05-31

A system and method for determining stator winding resistance in an AC motor is disclosed. The system includes a circuit having an input connectable to an AC source and an output connectable to an input terminal of an AC motor. The circuit includes at least one contactor and at least one switch to control current flow and terminal voltages in the AC motor. The system also includes a controller connected to the circuit and configured to modify a switching time of the at least one switch to create a DC component in an output of the system corresponding to an input to the AC motor and determine a stator winding resistance of the AC motor based on the injected DC component of the voltage and current.

Performance evaluation of traveling wave ultrasonic motor based on a model with visco-elastic friction layer on stator.

PubMed

Qu, Jianjun; Sun, Fengyan; Zhao, Chunsheng

2006-12-01

A new visco-elastic contact model of traveling wave ultrasonic motor (TWUSM) is proposed. In this model, the rotor is assumed to be rigid body and the friction material on stator teeth surface to be visco-elastic body. Both load characteristics of TWUSM, such as rotation speed, torque and efficiency, and effects of interface parameters between stator and rotor on output characteristic of TWUSM can be calculated and simulated numerically by using MATLAB method based on this model. This model is compared with that one of compliant slider and rigid stator. The results show that this model can obtain bigger stall torque. The simulated results are compared with test results, and found that their load characteristics have good agreement.

Core losses of an inverter-fed permanent magnet synchronous motor with an amorphous stator core under no-load

NASA Astrophysics Data System (ADS)

Denis, Nicolas; Kato, Yoshiyuki; Ieki, Masaharu; Fujisaki, Keisuke

2016-05-01

In this paper, an interior permanent magnet synchronous motor (IPMSM) with a stator core made of amorphous magnetic material (AMM) is presented. The IPMSM is driven by a voltage source three-phase inverter with classical pulse width modulation (PWM) control. The core losses under no-load condition are measured by experiment and compared to an equivalent IPMSM with a stator core made of NO steel. Under these conditions, the core losses are influenced by the stator, rotor and magnet shapes but also by the PWM carrier signal that implies a high frequency harmonic in the magnetic flux density. It is demonstrated that the AMM can reduce the core losses by about 56 %.

Numerical simulation of transonic compressor under circumferential inlet distortion and rotor/stator interference using harmonic balance method

NASA Astrophysics Data System (ADS)

Wang, Ziwei; Jiang, Xiong; Chen, Ti; Hao, Yan; Qiu, Min

2018-05-01

Simulating the unsteady flow of compressor under circumferential inlet distortion and rotor/stator interference would need full-annulus grid with a dual time method. This process is time consuming and needs a large amount of computational resources. Harmonic balance method simulates the unsteady flow in compressor on single passage grid with a series of steady simulations. This will largely increase the computational efficiency in comparison with the dual time method. However, most simulations with harmonic balance method are conducted on the flow under either circumferential inlet distortion or rotor/stator interference. Based on an in-house CFD code, the harmonic balance method is applied in the simulation of flow in the NASA Stage 35 under both circumferential inlet distortion and rotor/stator interference. As the unsteady flow is influenced by two different unsteady disturbances, it leads to the computational instability. The instability can be avoided by coupling the harmonic balance method with an optimizing algorithm. The computational result of harmonic balance method is compared with the result of full-annulus simulation. It denotes that, the harmonic balance method simulates the flow under circumferential inlet distortion and rotor/stator interference as precise as the full-annulus simulation with a speed-up of about 8 times.

A Piezoelectric Micromotor with a Stator of φ=1.6 mm and l=4 mm Using Bulk PZT

NASA Astrophysics Data System (ADS)

Cagatay, Serra; Koc, Burhanettin; Moses, Paul; Uchino, Kenji

2004-04-01

The smallest discrete piezoelectric ultrasonic motor using bulk ceramics was developed. We are proposing basically a two-part motor: stator and rotor. The stator of the present motor consists of a hollow metal brass tube with outer diameter of 1.6 mm, inner diameter of 0.8 mm and length of only 4 mm with 2 PZT plates bonded onto it. Owing to the asymmetrical stator surface, two degenerated orthogonal bending modes were slightly split, resulting in a wobbling motion. Thus, the motor can be driven by a single driving source. The rotor is a spring, which is basically different from previous designs, pressed at both ends to the stator by a pair of ferrules. Consequently, the length of the whole motor assembly was reduced significantly; a final motor length of only 5 mm was obtained. The working frequency under zero load was approximately 227-233 kHz. Although the size is small, relatively high power was obtained under an optimized load condition: torque of 0.06 mNm, maximum power of 3.2 mW with a speed of 118 rad/s, and maximum efficiency of 11% under 48 Vrms at 221 kHz.

Studying the development of asynchronous rolling of the rotor over the stator with the turbine unit protection systems having different response times

NASA Astrophysics Data System (ADS)

Shatokhin, V. F.

2014-07-01

The possibility to stabilize the developing asynchronous rolling of the rotor over the stator under the conditions of power unit protections coming in action with different response times is considered. Asynchronous rolling of the rotor over the stator may develop when the rotating rotor comes in contact with the stator at high amplitudes of vibration caused by an abrupt loss of rotor balancing, by forced or self-excited vibration of the rotor, and by other factors. The danger of asynchronous rolling is connected with almost instantaneous development of self-excited vibration of the rotor when it comes in contact with the stator and with the rotor vibration amplitudes and forces of interaction between the rotor and stator dangerous for the turbine unit integrity. It is assumed that the turbine unit protection systems come in action after the arrival of signal of exceeding the permissible vibration level and produce commands to disconnect the generator from the grid, and to stop the supply of working fluid into the flow path, due to which an accelerating torque ceases to act on the turbine unit shaft. The protection system response speed is determined by a certain time t = ABtime that is taken for its components to come in action from the commencement of the event (application of the signal) to closure of the stop valves. The time curves of the main rolling parameters as functions of the ABtime value are presented. It is shown that the response time of existing protection systems is not sufficient for efficiently damping the rolling phenomenon, although the use of an electrical protection system (with the response time equal to 0.40-0.45 s) may have a positive effect on stabilizing the vibration amplitudes to a certain extent during the rolling and on smoothing its dangerous consequences. The consequences of rotor rolling over the stator can be efficiently mitigated by increasing the energy losses in the rotor-stator system (especially in the stator) and by

Generator stator core vent duct spacer posts

DOEpatents

Griffith, John Wesley; Tong, Wei

2003-06-24

Generator stator cores are constructed by stacking many layers of magnetic laminations. Ventilation ducts may be inserted between these layers by inserting spacers into the core stack. The ventilation ducts allow for the passage of cooling gas through the core during operation. The spacers or spacer posts are positioned between groups of the magnetic laminations to define the ventilation ducts. The spacer posts are secured with longitudinal axes thereof substantially parallel to the core axis. With this structure, core tightness can be assured while maximizing ventilation duct cross section for gas flow and minimizing magnetic loss in the spacers.

Sequential cooling insert for turbine stator vane

DOEpatents

Jones, Russell B.; Krueger, Judson J.; Plank, William L.

2014-04-01

A sequential impingement cooling insert for a turbine stator vane that forms a double impingement for the pressure and suction sides of the vane or a triple impingement. The insert is formed from a sheet metal formed in a zigzag shape that forms a series of alternating impingement cooling channels with return air channels, where pressure side and suction side impingement cooling plates are secured over the zigzag shaped main piece. Another embodiment includes the insert formed from one or two blocks of material in which the impingement channels and return air channels are machined into each block.

Sequential cooling insert for turbine stator vane

DOEpatents

Jones, Russel B; Krueger, Judson J; Plank, William L

2014-11-04

A sequential impingement cooling insert for a turbine stator vane that forms a double impingement for the pressure and suction sides of the vane or a triple impingement. The insert is formed from a sheet metal formed in a zigzag shape that forms a series of alternating impingement cooling channels with return air channels, where pressure side and suction side impingement cooling plates are secured over the zigzag shaped main piece. Another embodiment includes the insert formed from one or two blocks of material in which the impingement channels and return air channels are machined into each block.

Two-dimensional cold-air cascade study of a film-cooled turbine stator blade. 1: Experimental results of pressure-surface film cooling tests

NASA Technical Reports Server (NTRS)

Moffitt, T. P.; Prust, H. W., Jr.; Bartlett, W. M.

1974-01-01

The effect of film coolant ejection from the pressure side of a stator blade was determined in a two-dimensional cascade. Stator exit surveys were made for each of six rows of coolant holes. Successive multirow tests were made with two, three, four, five, and six rows of coolant holes open. The results of the multirow tests are compared with the predicted multirow performance obtained by adding the single-row data. Results are presented in terms of stator primary-air efficiency as a function of coolant fraction.

Performance of a tandem-rotor/tandem-stator conical-flow compressor designed for a pressure ratio of 3

NASA Technical Reports Server (NTRS)

Wood, J. R.; Owen, A. K.; Schumann, L. F.

1982-01-01

A conical-flow compressor stage with a large radius change through the rotor was tested at three values of rotor tip clearance. The stage had a tandem rotor and a tandem stator. Peak efficiency at design speed was 0.774 at a pressure ratio of 2.613. The rotor was tested without the stator, and detailed survey data were obtained for each rotor blade row. Overall peak rotor efficiency was 0.871 at a pressure ratio of 2.952.

The reflection of evolving bearing faults in the stator current's extended park vector approach for induction machines

NASA Astrophysics Data System (ADS)

Corne, Bram; Vervisch, Bram; Derammelaere, Stijn; Knockaert, Jos; Desmet, Jan

2018-07-01

Stator current analysis has the potential of becoming the most cost-effective condition monitoring technology regarding electric rotating machinery. Since both electrical and mechanical faults are detected by inexpensive and robust current-sensors, measuring current is advantageous on other techniques such as vibration, acoustic or temperature analysis. However, this technology is struggling to breach into the market of condition monitoring as the electrical interpretation of mechanical machine-problems is highly complicated. Recently, the authors built a test-rig which facilitates the emulation of several representative mechanical faults on an 11 kW induction machine with high accuracy and reproducibility. Operating this test-rig, the stator current of the induction machine under test can be analyzed while mechanical faults are emulated. Furthermore, while emulating, the fault-severity can be manipulated adaptively under controllable environmental conditions. This creates the opportunity of examining the relation between the magnitude of the well-known current fault components and the corresponding fault-severity. This paper presents the emulation of evolving bearing faults and their reflection in the Extended Park Vector Approach for the 11 kW induction machine under test. The results confirm the strong relation between the bearing faults and the stator current fault components in both identification and fault-severity. Conclusively, stator current analysis increases reliability in the application as a complete, robust, on-line condition monitoring technology.

Secondary flow spanwise deviation model for the stators of NASA middle compressor stages

NASA Technical Reports Server (NTRS)

Roberts, W. B.; Sandercock, D. M.

1984-01-01

A model of the spanwise variation of deviation for stator blades is presented. Deviation is defined as the difference between the passage mean flow angle and the metal angle at the outlet of a blade element of an axial compressor stage. The variation of deviation is taken as the difference above or below that predicted by blade element, (i.e., two-dimensional) theory at any spanwise location. The variation of deviation is dependent upon the blade camber, solidity and inlet boundary layer thickness at the hub or tip end-wall, and the blade channel aspect ratio. If these parameters are known or can be calculated, the model provides a reasonable approximation of the spanwise variation of deviation for most compressor middle stage stators operating at subsonic inlet Mach numbers.

The C-terminal periplasmic domain of MotB is responsible for load-dependent control of the number of stators of the bacterial flagellar motor.

PubMed

Castillo, David J; Nakamura, Shuichi; Morimoto, Yusuke V; Che, Yong-Suk; Kami-Ike, Nobunori; Kudo, Seishi; Minamino, Tohru; Namba, Keiichi

2013-01-01

The bacterial flagellar motor is made of a rotor and stators. In Salmonella it is thought that about a dozen MotA/B complexes are anchored to the peptidoglycan layer around the motor through the C-terminal peptidoglycan-binding domain of MotB to become active stators as well as proton channels. MotB consists of 309 residues, forming a single transmembrane helix (30-50), a stalk (51-100) and a C-terminal peptidoglycan-binding domain (101-309). Although the stalk is dispensable for torque generation by the motor, it is required for efficient motor performance. Residues 51 to 72 prevent premature proton leakage through the proton channel prior to stator assembly into the motor. However, the role of residues 72-100 remains unknown. Here, we analyzed the torque-speed relationship of the MotB(Δ72-100) motor. At a low speed near stall, this mutant motor produced torque at the wild-type level. Unlike the wild-type motor, however, torque dropped off drastically by slight decrease in external load and then showed a slow exponential decay over a wide range of load by its further reduction. Since it is known that the stator is a mechano-sensor and that the number of active stators changes in a load-dependent manner, we interpreted this unusual torque-speed relationship as anomaly in load-dependent control of the number of active stators. The results suggest that residues 72-100 of MotB is required for proper load-dependent control of the number of active stators around the rotor.

Impact of clocking on the aero-thermodynamics of a second stator tested in a one and a half stage HP turbine

NASA Astrophysics Data System (ADS)

Billiard, N.; Paniagua, Guillermo; Dénos, R.

2008-06-01

This paper focuses on the experimental investigation of the time-averaged and time-accurate aero-thermodynamics of a second stator tested in a 1.5 stage high-pressure turbine. The effect of clocking on aerodynamic and heat transfer are investigated. Tests are performed under engine representative conditions in the VKI compression tube CT3. The test program includes four different clocking positions, i.e. relative pitch-wise positions between the first and the second stator. Probes located upstream and downstream of the second stator provide the thermodynamic conditions of the flow field. On the second stator airfoil, measurements are taken around the blade profile at 15, 50 and 85% span with pressure sensors and thin-film gauges. Both time-averaged and time-resolved aspects of the flow field are addressed. Regarding the time-averaged results, clocking effects are mainly observed within the leading edge region of the second stator, the largest effects being observed at 15% span. The surface static pressure distribution is changed locally, hence affecting the overall airfoil performance. For one clocking position, the thermal load of the airfoil is noticeably reduced. Pressure fluctuations are attributed to the passage of the upstream transonic rotor and its associated pressure gradients. The pattern of these fluctuations changes noticeably as a function of clocking. The time-resolved variations of heat flux and static pressure are analyzed together showing that the major effect is due to a potential interaction. The time-resolved pressure distribution integrated along the second stator surface yields the unsteady forces on the vane. The magnitude of the unsteady force is very dependent on the clocking position.

Hermatically sealed motor blower unit with stator inside hollow armature

DOEpatents

Donelian, Khatchik O.

1976-01-20

13. A hermetically sealed motor blower unit comprising, in combination, a sealed housing having a thrust plate mounted therein and having a re-entrant wall forming a central cavity in said housing, a rotor within said housing, said rotor comprising an impeller, a hollow shaft embracing said cavity and a thrust collar adapted to cooperate with said thrust plate to support the axial thrust of said shaft, one or more journal bearings within said housing for supporting the radial load of said shaft and electric motor means for rotating said rotor, said motor means comprising a motor-stator located within said cavity and adapted to cooperate through a portion of said re-entrant wall with a motor-rotor mounted within said hollow shaft, the portion of said re-entrant wall located between said motor-stator and said motor-rotor being made relatively thin to reduce electrical losses, the bearing surfaces of said thrust plate, thrust collar and journal bearings being in communication with the discharge of said impeller, whereby fluid pumped by said impeller can flow directly to said bearing surfaces to lubricate them.

On Acoustic Source Specification for Rotor-Stator Interaction Noise Prediction

NASA Technical Reports Server (NTRS)

Nark, Douglas M.; Envia, Edmane; Burley, Caesy L.

2010-01-01

This paper describes the use of measured source data to assess the effects of acoustic source specification on rotor-stator interaction noise predictions. Specifically, the acoustic propagation and radiation portions of a recently developed coupled computational approach are used to predict tonal rotor-stator interaction noise from a benchmark configuration. In addition to the use of full measured data, randomization of source mode relative phases is also considered for specification of the acoustic source within the computational approach. Comparisons with sideline noise measurements are performed to investigate the effects of various source descriptions on both inlet and exhaust predictions. The inclusion of additional modal source content is shown to have a much greater influence on the inlet results. Reasonable agreement between predicted and measured levels is achieved for the inlet, as well as the exhaust when shear layer effects are taken into account. For the number of trials considered, phase randomized predictions follow statistical distributions similar to those found in previous statistical source investigations. The shape of the predicted directivity pattern relative to measurements also improved with phase randomization, having predicted levels generally within one standard deviation of the measured levels.

Stator Blade with Thermal Barrier Testing on Hot Gas Rig

NASA Image and Video Library

1975-04-21

A 1-foot long stator blade with a thermal coating subjected to intense heat in order to test its strength at the National Aeronautics and Space Administration (NASA) Lewis Research Center. Lewis researchers sought to determine optimal types of ceramic coatings to increase the durability of metals. The research was primarily intended to support the design of stator blades for high-performance axial-flow compressor and turbofan engines. The coatings reduced the temperature of the metal and the amount of required cooling. As engines became more and more sophisticated, compressor blades were required to withstand higher and higher temperatures. Lewis researchers developed a dual-layer thermal-barrier coating that could be applied to turbine vanes and blades and combustion liners. This new sprayable thermal-barrier coating was evaluated for its durability, strength, fatigue, and aerodynamic penalties. This hot-gas rig fired the scorching gas at the leading edge of a test blade. The blade was cooled by an internal air flow. The blades were heated at two different velocities during the program. When using Mach 0.3 gases the entire heating and cooling cycle only lasted 30 seconds. The cycle lasted 60 minutes during tests at Mach 1.

Industrial stator vane with sequential impingement cooling inserts

DOEpatents

Jones, Russell B; Fedock, John A; Goebel, Gloria E; Krueger, Judson J; Rawlings, Christopher K; Memmen, Robert L

2013-08-06

A turbine stator vane for an industrial engine, the vane having two impingement cooling inserts that produce a series of impingement cooling from the pressure side to the suction side of the vane walls. Each insert includes a spar with a row of alternating impingement cooling channels and return air channels extending in a radial direction. Impingement cooling plates cover the two sides of the insert and having rows of impingement cooling holes aligned with the impingement cooling channels and return air openings aligned with the return air channel.

Flexible stator control on the Galileo spacecraft

NASA Technical Reports Server (NTRS)

Kopf, E. H.; Brown, T. K.; Marsh, E. L.

1979-01-01

Galileo is a dual-spin spacecraft designed to deliver a probe to Jupiter and then orbit the planet. The stator, or despun section, contains four flexible modes below 10 Hz and the despun actuator is separated from the inertial sensors by this flexibility. Control loop separation by bandwidth proved unacceptable due to performance requirements. To obtain the desired performance, a control scheme was devised which consists of three parts. First, flexibility damping and control notch filtering are accomplished by phase locked loop techniques. Second, slewing maneuvers are produced by torque profiles which are nonexcitatory to the structure. Finally, a low bandwidth perturbation controller is supplied to remove spacecraft disturbances.

Flexibility within the rotor and stators of the vacuolar H+-ATPase.

PubMed

Song, Chun Feng; Papachristos, Kostas; Rawson, Shaun; Huss, Markus; Wieczorek, Helmut; Paci, Emanuele; Trinick, John; Harrison, Michael A; Muench, Stephen P

2013-01-01

The V-ATPase is a membrane-bound protein complex which pumps protons across the membrane to generate a large proton motive force through the coupling of an ATP-driven 3-stroke rotary motor (V1) to a multistroke proton pump (Vo). This is done with near 100% efficiency, which is achieved in part by flexibility within the central rotor axle and stator connections, allowing the system to flex to minimise the free energy loss of conformational changes during catalysis. We have used electron microscopy to reveal distinctive bending along the V-ATPase complex, leading to angular displacement of the V1 domain relative to the Vo domain to a maximum of ~30°. This has been complemented by elastic network normal mode analysis that shows both flexing and twisting with the compliance being located in the rotor axle, stator filaments, or both. This study provides direct evidence of flexibility within the V-ATPase and by implication in related rotary ATPases, a feature predicted to be important for regulation and their high energetic efficiencies.

A bio-hybrid DNA rotor-stator nanoengine that moves along predefined tracks.

PubMed

Valero, Julián; Pal, Nibedita; Dhakal, Soma; Walter, Nils G; Famulok, Michael

2018-06-01

Biological motors are highly complex protein assemblies that generate linear or rotary motion, powered by chemical energy. Synthetic motors based on DNA nanostructures, bio-hybrid designs or synthetic organic chemistry have been assembled. However, unidirectionally rotating biomimetic wheel motors with rotor-stator units that consume chemical energy are elusive. Here, we report a bio-hybrid nanoengine consisting of a catalytic stator that unidirectionally rotates an interlocked DNA wheel, powered by NTP hydrolysis. The engine consists of an engineered T7 RNA polymerase (T7RNAP-ZIF) attached to a dsDNA nanoring that is catenated to a rigid rotating dsDNA wheel. The wheel motor produces long, repetitive RNA transcripts that remain attached to the engine and are used to guide its movement along predefined ssDNA tracks arranged on a DNA nanotube. The simplicity of the design renders this walking nanoengine adaptable to other biological nanoarchitectures, facilitating the construction of complex bio-hybrid structures that achieve NTP-driven locomotion.

A bio-hybrid DNA rotor-stator nanoengine that moves along predefined tracks

NASA Astrophysics Data System (ADS)

Valero, Julián; Pal, Nibedita; Dhakal, Soma; Walter, Nils G.; Famulok, Michael

2018-06-01

Biological motors are highly complex protein assemblies that generate linear or rotary motion, powered by chemical energy. Synthetic motors based on DNA nanostructures, bio-hybrid designs or synthetic organic chemistry have been assembled. However, unidirectionally rotating biomimetic wheel motors with rotor-stator units that consume chemical energy are elusive. Here, we report a bio-hybrid nanoengine consisting of a catalytic stator that unidirectionally rotates an interlocked DNA wheel, powered by NTP hydrolysis. The engine consists of an engineered T7 RNA polymerase (T7RNAP-ZIF) attached to a dsDNA nanoring that is catenated to a rigid rotating dsDNA wheel. The wheel motor produces long, repetitive RNA transcripts that remain attached to the engine and are used to guide its movement along predefined ssDNA tracks arranged on a DNA nanotube. The simplicity of the design renders this walking nanoengine adaptable to other biological nanoarchitectures, facilitating the construction of complex bio-hybrid structures that achieve NTP-driven locomotion.

Aerodynamic performances of three fan stator designs operating with rotor having tip speed of 337 meters per second and pressure ratio of 1.54. 1: Experimental performance

NASA Technical Reports Server (NTRS)

Gelder, T. F.

1980-01-01

The aerodynamic performances of four stator-blade rows are presented and evaluated. The aerodynamic designs of two of these stators were compromised to reduce noise, a third design was not. On a calculated operating line passing through the design point pressure ratio, the best stator had overall pressure-ratio and efficiency decrements of 0.031 and 0.044, respectively, providing a stage pressure ratio of 1.483 and efficiency of 0.865. The other stators showed some correctable deficiencies due partly to the design compromises for noise. In the end-wall regions blade-element losses were significantly less for the shortest chord studied.

Low Speed, 2-D Rotor/Stator Active Noise Control at the Source Demonstration

NASA Technical Reports Server (NTRS)

Simonich, John C.; Kousen, Ken A.; Zander, Anthony C.; Bak, Michael; Topol, David A.

1997-01-01

Wake/blade-row interaction noise produced by the Annular Cascade Facility at Purdue University has been modeled using the LINFLO analysis. Actuator displacements needed for complete cancellation of the propagating acoustic response modes have been determined, along with the associated actuator power requirements. As an alternative, weighted least squares minimization of the total far-field sound power using individual actuators has also been examined. Attempts were made to translate the two-dimensional aerodynamic results into three-dimensional actuator requirements. The results lie near the limit of present actuator technology. In order to investigate the concept of noise control at the source for active rotor/stator noise control at the source, various techniques for embedding miniature actuators into vanes were examined. Numerous miniature speaker arrangements were tested and analyzed to determine their suitability as actuators for a demonstration test in the Annular Cascade Facility at Purdue. The best candidates demonstrated marginal performance. An alternative concept to using vane mounted speakers as control actuators was developed and tested. The concept uses compression drivers which are mounted externally to the stator vanes. Each compression driver is connected via a tube to an air cavity in the stator vane, from which the driver signal radiates into the working section of the experimental rig. The actual locations and dimensions of the actuators were used as input parameters for a LINFLO computational analysis of the actuator displacements required for complete cancellation of tones in the Purdue experimental rig. The actuators were designed and an arrangement determined which is compatible with the Purdue experimental rig and instrumentation. Experimental tests indicate that the actuators are capable of producing equivalent displacements greater than the requirements predicted by the LINFLO analysis. The acoustic output of the actuators was also found

Electromagnetic Radial Forces in a Hybrid Eight-Stator-Pole, Six-Rotor-Pole Bearingless Switched-Reluctance Motor

NASA Technical Reports Server (NTRS)

Morrison, Carlos R.; Siebert, Mark W.; Ho, Eric J.

2007-01-01

Analysis and experimental measurement of the electromagnet force loads on the hybrid rotor in a novel bearingless switched-reluctance motor (BSRM) have been performed. A BSRM has the combined characteristics of a switched-reluctance motor and a magnetic bearing. The BSRM has an eight-pole stator and a six-pole hybrid rotor, which is composed of circular and scalloped lamination segments. The hybrid rotor is levitated using only one set of stator poles. A second set of stator poles imparts torque to the scalloped portion of the rotor, which is driven in a traditional switched reluctance manner by a processor. Analysis was done for nonrotating rotor poles that were oriented to achieve maximum and minimum radial force loads on the rotor. The objective is to assess whether simple one-dimensional magnetic circuit analysis is sufficient for preliminary evaluation of this machine, which may exhibit strong three-dimensional electromagnetic field behavior. Two magnetic circuit geometries, approximating the complex topology of the magnetic fields in and around the hybrid rotor, were employed in formulating the electromagnetic radial force equations. Reasonable agreement between the experimental results and the theoretical predictions was obtained with typical magnetic bearing derating factors applied to the predictions.

On the Stator Slot Geometry of a Cable Wound Generator for Hydrokinetic Energy Conversion

PubMed Central

Grabbe, Mårten; Leijon, Mats

2015-01-01

The stator slot geometry of a cable wound permanent magnet synchronous generator for hydrokinetic energy conversion is evaluated. Practical experience from winding two cable wound generators is used to propose optimized dimensions of different parts in the stator slot geometry. A thorough investigation is performed through simulations of how small geometrical changes alter the generator performance. The finite element method (FEM) is used to model the generator and the simulations show that small changes in the geometry can have large effect on the performance of the generator. Furthermore, it is concluded that the load angle is especially sensitive to small geometrical changes. A new generator design is proposed which shows improved efficiency, reduced weight, and a possibility to decrease the expensive permanent magnet material by almost one-fifth. PMID:25879072

Sparse Reconstruction for Temperature Distribution Using DTS Fiber Optic Sensors with Applications in Electrical Generator Stator Monitoring

PubMed Central

Bazzo, João Paulo; Pipa, Daniel Rodrigues; da Silva, Erlon Vagner; Martelli, Cicero; Cardozo da Silva, Jean Carlos

2016-01-01

This paper presents an image reconstruction method to monitor the temperature distribution of electric generator stators. The main objective is to identify insulation failures that may arise as hotspots in the structure. The method is based on temperature readings of fiber optic distributed sensors (DTS) and a sparse reconstruction algorithm. Thermal images of the structure are formed by appropriately combining atoms of a dictionary of hotspots, which was constructed by finite element simulation with a multi-physical model. Due to difficulties for reproducing insulation faults in real stator structure, experimental tests were performed using a prototype similar to the real structure. The results demonstrate the ability of the proposed method to reconstruct images of hotspots with dimensions down to 15 cm, representing a resolution gain of up to six times when compared to the DTS spatial resolution. In addition, satisfactory results were also obtained to detect hotspots with only 5 cm. The application of the proposed algorithm for thermal imaging of generator stators can contribute to the identification of insulation faults in early stages, thereby avoiding catastrophic damage to the structure. PMID:27618040

Sparse Reconstruction for Temperature Distribution Using DTS Fiber Optic Sensors with Applications in Electrical Generator Stator Monitoring.

PubMed

Bazzo, João Paulo; Pipa, Daniel Rodrigues; da Silva, Erlon Vagner; Martelli, Cicero; Cardozo da Silva, Jean Carlos

2016-09-07

This paper presents an image reconstruction method to monitor the temperature distribution of electric generator stators. The main objective is to identify insulation failures that may arise as hotspots in the structure. The method is based on temperature readings of fiber optic distributed sensors (DTS) and a sparse reconstruction algorithm. Thermal images of the structure are formed by appropriately combining atoms of a dictionary of hotspots, which was constructed by finite element simulation with a multi-physical model. Due to difficulties for reproducing insulation faults in real stator structure, experimental tests were performed using a prototype similar to the real structure. The results demonstrate the ability of the proposed method to reconstruct images of hotspots with dimensions down to 15 cm, representing a resolution gain of up to six times when compared to the DTS spatial resolution. In addition, satisfactory results were also obtained to detect hotspots with only 5 cm. The application of the proposed algorithm for thermal imaging of generator stators can contribute to the identification of insulation faults in early stages, thereby avoiding catastrophic damage to the structure.

Reduced Perceived Noise Low Tip Speed Fans as a Result of Abandoning Cutoff Stator Vane Numbers

NASA Technical Reports Server (NTRS)

Dittmar, James

1998-01-01

As fan tip speeds are reduced, broadband noise is becoming more important in the calculation of perceived noise. Past experience indicates that lower vane number stators with either constant chord or constant solidity may be a way to reduce broadband noise caused by the interaction of the rotor wake turbulence with the stators. A baseline fan and a low blade number fan were investigated to determine if a noise reduction was possible. The low vane number fan showed a 2 PndB and a 1.5 PNLT noise reduction. These reductions show that this is a viable technique for reducing the perceived noise of low tip speed fans.

Single-stage experimental evaluation of tandem-airfoil rotor and stator blading for compressors. Part 1: Analysis and design of stages A, B, and C

NASA Technical Reports Server (NTRS)

Brent, J. A.; Cheatham, J. G.; Nilsen, A. W.

1972-01-01

A conventional rotor and stator, two dual-airfoil tandem rotors, and one dual-airfoil tandem stator were designed. The two tandem rotors were each designed with different percentages of the overall lift produced by the front airfoil. Velocity diagrams and blade leading and trailing edge metal angles selected for the conventional rotor and stator blading were used in the design of the tandem blading. Rotor inlet hub/tip ratio was 0.8. Design values of rotor tip velocity and stage pressure ratio were 757 ft/sec and 1.30, respectively.

Achieving more reliable operation of turbine generators at nuclear power plants by improving the water chemistry of the generator stator cooling system

NASA Astrophysics Data System (ADS)

Tyapkov, V. F.; Chudakova, I. Yu.; Alekseenko, O. A.

2011-08-01

Ways of improving the water chemistry used in the turbine generator stator's cooling systems at Russian nuclear power plants are considered. Data obtained from operational chemical monitoring of indicators characterizing the quality of cooling water in the turbine generator stator cooling systems of operating power units at nuclear power plants are presented.

Bearing failure detection of micro wind turbine via power spectral density analysis for stator current signals spectrum

NASA Astrophysics Data System (ADS)

Mahmood, Faleh H.; Kadhim, Hussein T.; Resen, Ali K.; Shaban, Auday H.

2018-05-01

The failure such as air gap weirdness, rubbing, and scrapping between stator and rotor generator arise unavoidably and may cause extremely terrible results for a wind turbine. Therefore, we should pay more attention to detect and identify its cause-bearing failure in wind turbine to improve the operational reliability. The current paper tends to use of power spectral density analysis method of detecting internal race and external race bearing failure in micro wind turbine by estimation stator current signal of the generator. The failure detector method shows that it is well suited and effective for bearing failure detection.

Load- and polysaccharide-dependent activation of the Na+-type MotPS stator in the Bacillus subtilis flagellar motor.

PubMed

Terahara, Naoya; Noguchi, Yukina; Nakamura, Shuichi; Kami-Ike, Nobunori; Ito, Masahiro; Namba, Keiichi; Minamino, Tohru

2017-04-05

The flagellar motor of Bacillus subtilis possesses two distinct H + -type MotAB and Na + -type MotPS stators. In contrast to the MotAB motor, the MotPS motor functions efficiently at elevated viscosity in the presence of 200 mM NaCl. Here, we analyzed the torque-speed relationship of the Bacillus MotAB and MotPS motors over a wide range of external loads. The stall torque of the MotAB and MotPS motors at high load was about 2,200 pN nm and 220 pN nm, respectively. The number of active stators in the MotAB and MotPS motors was estimated to be about ten and one, respectively. However, the number of functional stators in the MotPS motor was increased up to ten with an increase in the concentration of a polysaccharide, Ficoll 400, as well as in the load. The maximum speeds of the MotAB and MotPS motors at low load were about 200 Hz and 50 Hz, respectively, indicating that the rate of the torque-generation cycle of the MotPS motor is 4-fold slower than that of the MotAB motor. Domain exchange experiments showed that the C-terminal periplasmic domain of MotS directly controls the assembly and disassembly dynamics of the MotPS stator in a load- and polysaccharide-dependent manner.

Load- and polysaccharide-dependent activation of the Na+-type MotPS stator in the Bacillus subtilis flagellar motor

PubMed Central

Terahara, Naoya; Noguchi, Yukina; Nakamura, Shuichi; Kami-ike, Nobunori; Ito, Masahiro; Namba, Keiichi; Minamino, Tohru

2017-01-01

The flagellar motor of Bacillus subtilis possesses two distinct H+-type MotAB and Na+-type MotPS stators. In contrast to the MotAB motor, the MotPS motor functions efficiently at elevated viscosity in the presence of 200 mM NaCl. Here, we analyzed the torque-speed relationship of the Bacillus MotAB and MotPS motors over a wide range of external loads. The stall torque of the MotAB and MotPS motors at high load was about 2,200 pN nm and 220 pN nm, respectively. The number of active stators in the MotAB and MotPS motors was estimated to be about ten and one, respectively. However, the number of functional stators in the MotPS motor was increased up to ten with an increase in the concentration of a polysaccharide, Ficoll 400, as well as in the load. The maximum speeds of the MotAB and MotPS motors at low load were about 200 Hz and 50 Hz, respectively, indicating that the rate of the torque-generation cycle of the MotPS motor is 4-fold slower than that of the MotAB motor. Domain exchange experiments showed that the C-terminal periplasmic domain of MotS directly controls the assembly and disassembly dynamics of the MotPS stator in a load- and polysaccharide-dependent manner. PMID:28378843

The impact of different stator and rotor slot number combinations on iron losses of a three-phase induction motor at no-load

NASA Astrophysics Data System (ADS)

Marčič, T.; Štumberger, B.; Štumberger, G.; Hadžiselimović, M.; Zagradišnik, I.

The electromechanical characteristics of induction motors depend on the used stator and rotor slot combination. The correlation between the usage of different stator and rotor slot number combinations, magnetic flux density distributions, no-load iron losses and rated load winding over-temperatures for a specific induction motor is presented. The motor's magnetic field was analyzed by traces of the magnetic flux density vector, obtained by FEM. Post-processing of FE magnetic field solution was used for posterior iron loss calculation of the motor iron loss at no-load. The examined motor stator lamination had 36 semi-closed slots and the rotor laminations had 28, 33, 34, 44 and 46 semi-closed slots.

PSP Measurement of Stator Vane Surface Pressures in a High Speed Fan

NASA Technical Reports Server (NTRS)

Lepicovsky, Jan

1998-01-01

This paper presents measurements of static pressures on the stator vane suction side of a high-speed single stage fan using the technique of pressure sensitive paint (PSP). The paper illustrates development in application of the relatively new experimental technique to the complex environment of internal flows in turbomachines. First, there is a short explanation of the physics of the PSP technique and a discussion of calibration methods for pressure sensitive paint in the turbomachinery environment. A description of the image conversion process follows. The recorded image of the stator vane pressure field is skewed due to the limited optical access and must be converted to the meridional plane projection for comparison with analytical predictions. The experimental results for seven operating conditions along an off-design rotational speed line are shown in a concise form, including performance map points, mindspan static tap pressure distributions, and vane suction side pressure fields. Then, a comparison between static tap and pressure sensitive paint data is discussed. Finally, the paper lists shortcomings of the pressure sensitive paint technology and lessons learned in this high-speed fan application.

Magnetic characterization of the stator core of a high-speed motor made of an ultrathin electrical steel sheet using the magnetic property evaluation system

NASA Astrophysics Data System (ADS)

Oka, Mohachiro; Enokizono, Masato; Mori, Yuji; Yamazaki, Kazumasa

2018-04-01

Recently, the application areas for electric motors have been expanding. For instance, electric motors are used in new technologies such as rovers, drones, cars, and robots. The motor used in such machinery should be small, high-powered, highly-efficient, and high-speed. In such motors, loss at high-speed rotation must be especially minimal. Eddy-current loss in the stator core is known to increase greatly during loss at high-speed rotation of the motor. To produce an efficient high-speed motor, we are developing a stator core for a motor using an ultrathin electrical steel sheet with only a small amount of eddy-current loss. Furthermore, the magnetic property evaluation for efficient, high-speed motor stator cores that use conventional commercial frequency is insufficient. Thus, we made a new high-speed magnetic property evaluation system to evaluate the magnetic properties of the efficient high-speed motor stator core. This system was composed of high-speed A/D converters, D/A converters, and a high-speed power amplifier. In experiments, the ultrathin electrical steel sheet dramatically suppressed iron loss and, in particular, eddy-current loss. In addition, a new high-speed magnetic property evaluation system accurately evaluated the magnetic properties of the efficient high-speed motor stator core.

Experimental measurements concerning the stator insulation partial discharge level of a hydro-generator of high power

NASA Astrophysics Data System (ADS)

Haţiegan, C.; Răduca, E.; Popescu, C.; Hamat, C. O.; Băra, A.; Anghel, D.; Pîrşan, D. A.

2018-01-01

The paper presents a determining and evaluating method from an experimental point of view of the partial discharges level from the insulation of the stator of a synchronous hydro-generator of high power that appear at different temperatures. The temperature is measured directly on the coil with placed thermo-resistant elements between the superior and inferior bars. Also, the level of partial discharges with the coil age in a cold state, at the temperature level of the surrounding environment from within the stator, but also in a warm state at different temperatures, is measured. Through this method there is created the possibility of highlighting some eventual degradations of the coil insulation of a hydro-generator.

Influence of the Operational Wear of the Stator Parts of Shroud Seals on the Economic Efficiency of the Steam Turbines

NASA Astrophysics Data System (ADS)

Kostyuk, A. G.; Dmitriev, S. S.; Petrunin, B. N.; Gusev, A. A.

2018-01-01

During the operation of steam turbines under transient conditions, due to different thermal expansion of the stator and rotor parts in the radial and axial directions, the clearances fixed in the course of assembling the seals of the flow path change, which causes rubbing in the seals and the wear of the latter. This inevitably increases the leakages through the seals. A particularly large difference in the relative axial and radial displacements of the rotor and stator parts is observed during the turbine start-ups when the difference in their temperature expansion is maximal. Upon the turbine stops, the turbine shafting runs down freely, as a rule, passing through all critical speeds at which the amplitude of the shafting oscillations reach their peak values, which also leads to seizures in the seals and their wear and tear. The seizures in the seals may also be a consequence of the eccentricity between the rotor and stator caused by the thermal strain of the stator, incorrect choice of the clearances, floating-up of the rotor in the bearing, and many other factors. Recently, standard shroud labyrinth seals are being replaced in the steam turbines by seals with honeycomb stator inserts, the design of which allows the ridges to cut into the honeycomb surface without damaging the former, which allows fixing a radial clearance in the seals of 0.5 mm. On the honeycomb surface where the ridges touch it, grooves are cut through. The wear of the shroud seals reduces the efficiency of the steam turbines during the operation to the greatest degree. However, by the present there have been no exact quantitative data available on the change in the leakage through the worn-out honeycomb seals. The paper presents the results of comparative experimental studies on the flow and power characteristics of seal models with smooth and honeycomb stator parts for various degrees of their wear. The studies showed that the leakages through the worn-out stator parts of the honeycomb seals

Sequential cooling insert for turbine stator vane

DOEpatents

Jones, Russel B

2017-04-04

A sequential flow cooling insert for a turbine stator vane of a small gas turbine engine, where the impingement cooling insert is formed as a single piece from a metal additive manufacturing process such as 3D metal printing, and where the insert includes a plurality of rows of radial extending impingement cooling air holes alternating with rows of radial extending return air holes on a pressure side wall, and where the insert includes a plurality of rows of chordwise extending second impingement cooling air holes on a suction side wall. The insert includes alternating rows of radial extending cooling air supply channels and return air channels that form a series of impingement cooling on the pressure side followed by the suction side of the insert.

Prediction and Optimization of Key Performance Indicators in the Production of Stator Core Using a GA-NN Approach

NASA Astrophysics Data System (ADS)

Rajora, M.; Zou, P.; Xu, W.; Jin, L.; Chen, W.; Liang, S. Y.

2017-12-01

With the rapidly changing demands of the manufacturing market, intelligent techniques are being used to solve engineering problems due to their ability to handle nonlinear complex problems. For example, in the conventional production of stator cores, it is relied upon experienced engineers to make an initial plan on the number of compensation sheets to be added to achieve uniform pressure distribution throughout the laminations. Additionally, these engineers must use their experience to revise the initial plans based upon the measurements made during the production of stator core. However, this method yields inconsistent results as humans are incapable of storing and analysing large amounts of data. In this article, first, a Neural Network (NN), trained using a hybrid Levenberg-Marquardt (LM) - Genetic Algorithm (GA), is developed to assist the engineers with the decision-making process. Next, the trained NN is used as a fitness function in an optimization algorithm to find the optimal values of the initial compensation sheet plan with the aim of minimizing the required revisions during the production of the stator core.

Simulative and experimental investigation on stator winding turn and unbalanced supply voltage fault diagnosis in induction motors using Artificial Neural Networks.

PubMed

Lashkari, Negin; Poshtan, Javad; Azgomi, Hamid Fekri

2015-11-01

The three-phase shift between line current and phase voltage of induction motors can be used as an efficient fault indicator to detect and locate inter-turn stator short-circuit (ITSC) fault. However, unbalanced supply voltage is one of the contributing factors that inevitably affect stator currents and therefore the three-phase shift. Thus, it is necessary to propose a method that is able to identify whether the unbalance of three currents is caused by ITSC or supply voltage fault. This paper presents a feedforward multilayer-perceptron Neural Network (NN) trained by back propagation, based on monitoring negative sequence voltage and the three-phase shift. The data which are required for training and test NN are generated using simulated model of stator. The experimental results are presented to verify the superior accuracy of the proposed method. Copyright © 2015. Published by Elsevier Ltd.

Design and Performance Improvement of AC Machines Sharing a Common Stator

NASA Astrophysics Data System (ADS)

Guo, Lusu

With the increasing demand on electric motors in various industrial applications, especially electric powered vehicles (electric cars, more electric aircrafts and future electric ships and submarines), both synchronous reluctance machines (SynRMs) and interior permanent magnet (IPM) machines are recognized as good candidates for high performance variable speed applications. Developing a single stator design which can be used for both SynRM and IPM motors is a good way to reduce manufacturing and maintenance cost. SynRM can be used as a low cost solution for many electric driving applications and IPM machines can be used in power density crucial circumstances or work as generators to meet the increasing demand for electrical power on board. In this research, SynRM and IPM machines are designed sharing a common stator structure. The prototype motors are designed with the aid of finite element analysis (FEA). Machine performances with different stator slot and rotor pole numbers are compared by FEA. An 18-slot, 4-pole structure is selected based on the comparison for this prototype design. Sometimes, torque pulsation is the major drawback of permanent magnet synchronous machines. There are several sources of torque pulsations, such as back-EMF distortion, inductance variation and cogging torque due to presence of permanent magnets. To reduce torque pulsations in permanent magnet machines, all the efforts can be classified into two categories: one is from the design stage, the structure of permanent magnet machines can be optimized with the aid of finite element analysis. The other category of reducing torque pulsation is after the permanent magnet machine has been manufactured or the machine structure cannot be changed because of other reasons. The currents fed into the permanent magnet machine can be controlled to follow a certain profile which will make the machine generate a smoother torque waveform. Torque pulsation reduction methods in both categories will be

Active Flow Separation Control of a Stator Vane Using Surface Injection in a Multistage Compressor Experiment

NASA Technical Reports Server (NTRS)

Culley, Dennis E.; Bright, Michelle M.; Prahst, Patricia S.; Strazisar, Anthony J.

2003-01-01

Micro-flow control actuation embedded in a stator vane was used to successfully control separation and improve near stall performance in a multistage compressor rig at NASA Glenn. Using specially designed stator vanes configured with internal actuation to deliver pulsating air through slots along the suction surface, a research study was performed to identify performance benefits using this microflow control approach. Pressure profiles and unsteady pressure measurements along the blade surface and at the shroud provided a dynamic look at the compressor during microflow air injection. These pressure measurements lead to a tracking algorithm to identify the onset of separation. The testing included steady air injection at various slot locations along the vane. The research also examined the benefit of pulsed injection and actively controlled air injection along the stator vane. Two types of actuation schemes were studied, including an embedded actuator for on-blade control. Successful application of an online detection and flow control scheme will be discussed. Testing showed dramatic performance benefit for flow reattachment and subsequent improvement in diffusion through the use of pulsed controlled injection. The paper will discuss the experimental setup, the blade configurations, and preliminary CFD results which guided the slot location along the blade. The paper will also show the pressure profiles and unsteady pressure measurements used to track flow control enhancement, and will conclude with the tracking algorithm for adjusting the control.

The use of cowl camber and taper to reduce rotor/stator interaction noise

NASA Technical Reports Server (NTRS)

Martinez, R.

1995-01-01

The project had two specific technical objectives: (1) to develop a realistic three-dimensional model of tonal noise due to rotor/stator interaction, as the input field for predictions of diffraction and dissipation by a lined cowl; and (2) to determine whether the generator curve of that cowl, or duct, could be 'steered' to yield substantially lower values of propulsor noise along the engine's fore and aft open sectors. The more general and important aim of their research is to provide the commercial aircraft industry with a useful predictive tool to help it meet its noise-reduction goals. The work has produced a tractable and yet realistic model of rotor/stator interaction noise. The blades in the fan stage are radially divergent, twisted, and of realistically wide chords to match the high frequencies and speeds of the sound-production process. The resulting three-dimensional acoustic nearfield insonifies the interior wall of the diffracting cowl, whose shape, incidentally, does not affect fore or aft noise significantly (but other factors do).

Analytical study on a two-dimensional plane of the off-design flow properties of tandem-bladed compressor stators

NASA Technical Reports Server (NTRS)

Sanger, N. L.

1973-01-01

The flow characteristics of several tandem bladed compressor stators were analytically evaluated over a range of inlet incidence angles. The ratios of rear-segment to front-segment chord and camber were varied. Results were also compared to the analytical performance of a reference solid blade section. All tandem blade sections exhibited lower calculated losses than the solid stator. But no one geometric configuration exhibited clearly superior characteristics. The front segment accepts the major effect of overall incidence angle change. Rear- to front-segment camber ratios of 4 and greater appeared to be limited by boundary-layer separation from the pressure surface of the rear segment.

System and method for determining stator winding resistance in an AC motor using motor drives

DOEpatents

Lu, Bin; Habetler, Thomas G; Zhang, Pinjia

2013-02-26

A system and method for determining the stator winding resistance of AC motors is provided. The system includes an AC motor drive having an input connectable to an AC source and an output connectable to an input terminal of an AC motor, a pulse width modulation (PWM) converter having switches therein to control current flow and terminal voltages in the AC motor, and a control system connected to the PWM converter. The control system generates a command signal to cause the PWM converter to control an output of the AC motor drive corresponding to an input to the AC motor, selectively generates a modified command signal to cause the PWM converter to inject a DC signal into the output of the AC motor drive, and determines a stator winding resistance of the AC motor based on the DC signal of at least one of the voltage and current.

Application of Synthetic Jets to Reduce Stator Flow Separation in a Low Speed Axial Compressor

NASA Technical Reports Server (NTRS)

Braunscheidel, Edward P.; Culley, Dennis E.; Zaman, Khairul B.M.Q.

2008-01-01

Flow control using synthetic jet injection has been applied in a low speed axial compressor. The synthetic jets were applied from the suction surface of a stator vane via a span-wise row of slots pitched in the streamwise direction. Actuation was provided externally from acoustic drivers coupled to the vane tip via flexible tubing. The acoustic resonance characteristics of the system, and the resultant jet velocities were obtained. The effects on the separated flow field for various jet velocities and frequencies were explored. Total pressure loss reductions across the vane passage were measured. The effect of synthetic jet injection was shown to be comparable to that of pulsatory injection with mass addition for stator vanes which had separated flow. While only a weak dependence of the beneficial effect was noted based on the excitation frequency, a strong dependence on the amplitude was observed at all frequencies.

Flow visualization for investigating stator losses in a multistage axial compressor

NASA Astrophysics Data System (ADS)

Smith, Natalie R.; Key, Nicole L.

2015-05-01

The methodology and implementation of a powder-paint-based flow visualization technique along with the illuminated flow physics are presented in detail for application in a three-stage axial compressor. While flow visualization often accompanies detailed studies, the turbomachinery literature lacks a comprehensive study which both utilizes flow visualization to interrupt the flow field and explains the intricacies of execution. Lessons learned for obtaining high-quality images of surface flow patterns are discussed in this study. Fluorescent paint is used to provide clear, high-contrast pictures of the recirculation regions on shrouded vane rows. An edge-finding image processing procedure is implemented to provide a quantitative measure of vane-to-vane variability in flow separation, which is approximately 7 % of the suction surface length for Stator 1. Results include images of vane suction side corner separations from all three stages at three loading conditions. Additionally, streakline patterns obtained experimentally are compared with those calculated from computational models. Flow physics associated with vane clocking and increased rotor tip clearance and their implications to stator loss are also investigated with this flow visualization technique. With increased rotor tip clearance, the vane surface flow patterns show a shift to larger separations and more radial flow at the tip. Finally, the effects of instrumentation on the flow field are highlighted.

An experimental investigation of the unsteady response of a stator located downstream of a propeller ingesting broadband turbulence

NASA Astrophysics Data System (ADS)

Lynch, Denis Aloysius, III

This experimental investigation examined the unsteady response of a stator located downstream of a four- or ten-bladed propeller encountering broadband turbulence. The response is manifested in a radiated acoustic field which can be directly attributed to the unsteady surface pressure loading on the stator by the turbulent flowfield. In order to characterize the unsteady response of the stator, a thorough analysis of the turbulent flowfield downstream of the propeller was completed. The analysis of the turbulent flowfield is organized in a manner which reflects the causal relationship between influences on the flowfield and the evolution of the flowfield itself. Mathematical models for each of these contributions, including the broadband and periodic contributions of the propeller wakes and modification of the inflow turbulence by the propeller, are presented and analyzed. A further mathematical model involving the prediction of correlation length scale aids in the accurate prediction of the radiated acoustic pressure based solely on fundamental turbulent flowfield measurements. Unsteady surface pressure measurements, originally intended to provide additional information about the response of the stator as it relates to the incoming flowfield, were found to be heavily contaminated by vibrational effects. Therefore, techniques involving cross-correlation measurements are developed to mathematically isolate the unsteady pressure signal. The success of these techniques suggests the strong possibility of future application in this area. Finally, the mathematical models developed to describe the flowfield downstream of the propeller are applied to the case of a twenty-bladed propeller. This case was selected due to the anticipated increased levels of modification of the inflow turbulence. Results provide further evidence that this complex flowfield may be fully and accurately represented using simple mathematical models supported by baseline empirical information.

High-loading low-speed fan study. 4: Data and performance with redesign stator and including a rotor tip casing treatment

NASA Technical Reports Server (NTRS)

Harley, K. G.; Odegard, P. A.; Burdsall, E. A.

1972-01-01

A single stage fan with a rotor tip speed of 1000 ft/sec(304.8 m/sec) and a hub-to-tip ratio of 0.392 was retested with a redesigned stator. Tests were conducted with uniform inlet, tip-radial, hub-radial, and circumferential inlet distortions. With uniform inlet flow, stall margin was improved 12 percentage points above that with the original stator. The fan demonstrated an efficiency of 0.883 and a stall margin of 15 percent at a pressure ratio of 1.488 and a specific flow of 41.17 lb/sec/sq ft. Tests were also made with a redesigned casing treatment consisting of skewed slots over the rotor blade tips. This casing treatment gave a 7 percentage point improvement in stall margin when tested with tip radial distortion (when the rotor tip initiated stall). Noise measurements at the fan inlet and exit indicate no effect from closing the stator 10 degrees, nor were there measurable effects from adding skewed slots over the blade tips.

Acoustic Reflection and Transmission of 2-Dimensional Rotors and Stators, Including Mode and Frequency Scattering Effects

NASA Technical Reports Server (NTRS)

Hanson, Donald B.

1999-01-01

A reduced order modeling scheme has been developed for the unsteady acoustic and vortical coupling between blade rows of a turbomachine. The essential behavior of the system is governed by modal scattering coefficients (i.e., reflection and transmission coefficients) of the rotor, stator, inlet and nozzle, which are calculated as if they were connected to non-reflecting ducts. The objective of this report is to identify fundamental behavior of these scattering coefficients for a better understanding of the role of blade row reflection and transmission in noise generation. A 2D flat plate unsteady cascade model is used for the analysis with the expectation that the general behavior presented herein will carry over to models that include more realistic flow and geometry. It is shown that stators scatter input waves into many modes at the same frequency whereas rotors scatter on frequency, or harmonic order. Important cases are shown here the rotor reflection coefficient is greater than unity; a mode at blade passing frequency (BPF) traveling from the stator with unit sound power is reflected by the rotor with more than unit power at 2xBPF and 3xBPE Analysis is presented to explain this unexpected phenomenon. Scattering curves are presented in a format chosen for design use and for physical interpretation. To aid in interpretation of the curves, formulas are derived for special condition where waveforms are parallel to perpendicular to the rotor.

Core losses of a permanent magnet synchronous motor with an amorphous stator core under inverter and sinusoidal excitations

NASA Astrophysics Data System (ADS)

Yao, Atsushi; Sugimoto, Takaya; Odawara, Shunya; Fujisaki, Keisuke

2018-05-01

We report core loss properties of permanent magnet synchronous motors (PMSM) with amorphous magnetic materials (AMM) core under inverter and sinusoidal excitations. To discuss the core loss properties of AMM core, a comparison with non-oriented (NO) core is also performed. In addition, based on both experiments and numerical simulations, we estimate higher (time and space) harmonic components of the core losses under inverter and sinusoidal excitations. The core losses of PMSM are reduced by about 59% using AMM stator core instead of NO core under sinusoidal excitation. We show that the average decrease obtained by using AMM instead of NO in the stator core is about 94% in time harmonic components.

Operation of a test bed axial-gap brushless dc rotor with a superconducting stator

DOE Office of Scientific and Technical Information (OSTI.GOV)

McKeever, J.W.; Sohns, C.W.; Schwenterly, S.W.

1993-08-01

A variable-speed axial-gap motor with a stator consisting of four liquid helium cooled superconducting electromagnets (two pole pairs) was built and proof tested up to 608 rpm in November 1990 as a tool for joint industry-laboratory evaluation of coils fabricated from high-temperature oxide superconductors. A second rotor was fabricated with improved materia winding configuration, and wire type, and the drive system was modified to eliminate current spiking. The modified motor was characterized to design speed, 188 rad/s (1800 rpm), to acquire a performance baseline for future comparison with that of high-temperature superconducting (HIS) wire. As it becomes commercially available, HTSmore » wire will replace the low-temperature electromagnet wire in a stator modified to control wire temperatures between 4 K and 77 K. Measurements of the superconducting electromagnetic field and locked rotor torque as functions of cryocurrent and dc current through two phases of the rotor, respectively, provided data to estimate power that could be developed by the rotor. Back emf and parasitic mechanical and electromagnetic drag torques were measured as functions of angular velocity to calculate actual rotor power developed and to quantify losses, which reduce the motor`s efficiency. A detailed measurement of motor power at design speed confirmed the developed power equation. When subsequently operated at the 33-A maximum available rotor current, the motor delivered 15.3 kill (20.5 hp) to the load. In a final test, the cryostat was operated at 2500 A, 200 A below its critical current. At rotor design current of 60 A and 2500 A stator current, the extrapolated developed power would be 44.2 kill (59.2 hp) with 94% efficiency.« less

Unsteady adjoint for large eddy simulation of a coupled turbine stator-rotor system

NASA Astrophysics Data System (ADS)

Talnikar, Chaitanya; Wang, Qiqi; Laskowski, Gregory

2016-11-01

Unsteady fluid flow simulations like large eddy simulation are crucial in capturing key physics in turbomachinery applications like separation and wake formation in flow over a turbine vane with a downstream blade. To determine how sensitive the design objectives of the coupled system are to control parameters, an unsteady adjoint is needed. It enables the computation of the gradient of an objective with respect to a large number of inputs in a computationally efficient manner. In this paper we present unsteady adjoint solutions for a coupled turbine stator-rotor system. As the transonic fluid flows over the stator vane, the boundary layer transitions to turbulence. The turbulent wake then impinges on the rotor blades, causing early separation. This coupled system exhibits chaotic dynamics which causes conventional adjoint solutions to diverge exponentially, resulting in the corruption of the sensitivities obtained from the adjoint solutions for long-time simulations. In this presentation, adjoint solutions for aerothermal objectives are obtained through a localized adjoint viscosity injection method which aims to stabilize the adjoint solution and maintain accurate sensitivities. Preliminary results obtained from the supercomputer Mira will be shown in the presentation.

Local heat transfer in turbine disk-cavities. I - Rotor and stator cooling with hub injection of coolant

NASA Astrophysics Data System (ADS)

Bunker, R. S.; Metzger, D. E.; Wittig, S.

1990-06-01

Detailed radial heat-transfer coefficient distributions applicable to the cooling of disk-cavity regions of gas turbines are obtained experimentally from local heat-transfer data on both the rotating and stationary surfaces of a parallel-geometry disk-cavity system. Attention is focused on the hub injection of a coolant over a wide range of parameters including disk rotational Reynolds numbers of 200,000 to 50,000, rotor/stator spacing-to-disk ratios of 0.025 to 0.15, and jet mass flow rates between 0.10 and 0.40 times the turbulent pumped flow rate of a free disk. It is shown that rotor heat transfer exhibits regions of impingement and rotational domination with a transition region between, while stator heat transfer displays flow reattachment and convection regions with an inner recirculation zone.

Differential Dengue Tropism & Neutralization: Potential Mechanisms of Pathogenesis

DTIC Science & Technology

2006-01-04

Dr. Guillermo Comach and Dr. Daria Camacho, Laboratorio Regional de Diagnostico e Investigacion del Dengue y otras Enfermedades Virales, Centro de... Enfermedades Virales, Centro de Investigaciones Biomedicas de la Universidad de Carabobo (LARDIDEV/BIOMED- UC), Maracay, Venezuela. 4Naval Medical Research

Unsteady flows in rotor-stator cascades

NASA Astrophysics Data System (ADS)

Lee, Yu-Tai; Bein, Thomas W.; Feng, Jin Z.; Merkle, Charles L.

1991-03-01

A time-accurate potential-flow calculation method has been developed for unsteady incompressible flows through two-dimensional multi-blade-row linear cascades. The method represents the boundary surfaces by distributing piecewise linear-vortex and constant-source singularities on discrete panels. A local coordinate is assigned to each independently moving object. Blade-shed vorticity is traced at each time step. The unsteady Kutta condition applied is nonlinear and requires zero blade trailing-edge loading at each time. Its influence on the solutions depends on the blade trailing-edge shapes. Steady biplane and cascade solutions are presented and compared to exact solutions and experimental data. Unsteady solutions are validated with the Wagner function for an airfoil moving impulsively from rest and the Theodorsen function for an oscillating airfoil. The shed vortex motion and its interaction with blades are calculated and compared to an analytic solution. For multi-blade-row cascade, the potential effect between blade rows is predicted using steady and quasi unsteady calculations. The accuracy of the predictions is demonstrated using experimental results for a one-stage turbine stator-rotor.

Aerodynamic performances of three fan stator designs operating with rotor having tip speed of 337 meters per second and pressure ratio of 1.54. Relation of analytical code calculations to experimental performance

NASA Technical Reports Server (NTRS)

Gelder, T. F.; Schmidt, J. F.; Esgar, G. M.

1980-01-01

A hub-to-shroud and a blade-to-blade internal-flow analysis code, both inviscid and basically subsonic, were used to calculate the flow parameters within four stator-blade rows. The produced ratios of maximum suction-surface velocity to trailing-edge velocity correlated well in the midspan region, with the measured total-parameters over the minimum-loss to near stall operating range for all stators and speeds studied. The potential benefits of a blade designed with the aid of these flow analysis codes are illustrated by a proposed redesign of one of the four stators studied. An overall efficiency improvement of 1.6 points above the peak measured for that stator is predicted for the redesign.

Analysis of coiled stator ultrasound motor: Fundamental study on analysis of wave propagation on acoustic waveguide for coiled stator

NASA Astrophysics Data System (ADS)

Ozeki, Seiya; Kurita, Keisuke; Uehara, Choyu; Nakane, Noriaki; Sato, Toshio; Takeuchi, Shinichi

2018-07-01

In our research group, we previously developed a coiled stator ultrasound motor (CS-USM) for medical applications such as intravascular ultrasound (IVUS) devices. However, wave propagation on acoustic waveguides has not been investigated sufficiently in previous studies. In this study, we analyze the propagation velocity of elastic waves from the simulated the vibration displacement mode profile along a straight line acoustic waveguide via three-dimensional finite element method (FEM). Concerning results, elastic waves with vibration displacement along the thickness direction show dispersion characteristics corresponding to the a0 and a1 mode plate waves (Lamb waves) in the acoustic waveguide. Our theoretical hypotheses of the propagation velocities were closely borne out by experimental results. We further find that the dispersion characteristic is affected by the width of the acoustic waveguide. We believe that our findings can contribute to improved CS-USM designs for practical application.

Toward Understanding Tip Leakage Flows in Small Compressor Cores Including Stator Leakage Flow

NASA Technical Reports Server (NTRS)

Berdanier, Reid A.; Key, Nicole L.

2017-01-01

The focus of this work was to provide additional data to supplement the work reported in NASA/CR-2015-218868 (Berdanier and Key, 2015b). The aim of that project was to characterize the fundamental flow physics and the overall performance effects due to increased rotor tip clearance heights in axial compressors. Data have been collected in the three-stage axial research compressor at Purdue University with a specific focus on analyzing the multistage effects resulting from the tip leakage flow. Three separate rotor tip clearances were studied with nominal tip clearance gaps of 1.5 percent, 3.0 percent, and 4.0 percent based on a constant annulus height. Overall compressor performance was previously investigated at four corrected speedlines (100 percent, 90 percent, 80 percent, and 68 percent) for each of the three tip clearance configurations. This study extends the previously published results to include detailed steady and time-resolved pressure data at two loading conditions, nominal loading (NL) and high loading (HL), on the 100 percent corrected speedline for the intermediate clearance level (3.0 percent). Steady detailed radial traverses of total pressure at the exit of each stator row are supported by flow visualization techniques to identify regions of flow recirculation and separation. Furthermore, detailed radial traverses of time-resolved total pressures at the exit of each rotor row have been measured with a fast-response pressure probe. These data were combined with existing three-component velocity measurements to identify a novel technique for calculating blockage in a multistage compressor. Time-resolved static pressure measurements have been collected over the rotor tips for all rotors with each of the three tip clearance configurations for up to five loading conditions along the 100 percent corrected speedline using fast-response piezoresistive pressure sensors. These time-resolved static pressure measurements reveal new knowledge about the

Predicting the Rotor-Stator Interaction Acoustics of a Ducted Fan Engine

NASA Technical Reports Server (NTRS)

Biedron, Robert T.; Rumsey, Christopher L.; Podboy, Gary G.; Dunn, M. H.

2001-01-01

A Navier-Stokes computation is performed for a ducted-fan configuration with the goal of predicting rotor-stator noise generation without having to resort to heuristic modeling. The calculated pressure field in the inlet region is decomposed into classical infinite-duct modes, which are then used in either a hybrid finite-element/Kirchhoff surface method or boundary integral equation method to calculate the far field noise. Comparisons with experimental data are presented, including rotor wake surveys and far field sound pressure levels for two blade passage frequency (BPF) tones.

Feasibility of Using PZT Actuators to Study the Dynamic Behavior of a Rotating Disk due to Rotor-Stator Interaction

PubMed Central

Presas, Alexandre; Egusquiza, Eduard; Valero, Carme; Valentin, David; Seidel, Ulrich

2014-01-01

In this paper, PZT actuators are used to study the dynamic behavior of a rotating disk structure due to rotor-stator interaction excitation. The disk is studied with two different surrounding fluids—air and water. The study has been performed analytically and validated experimentally. For the theoretical analysis, the natural frequencies and the associated mode shapes of the rotating disk in air and water are obtained with the Kirchhoff-Love thin plate theory coupled with the interaction with the surrounding fluid. A model for the Rotor Stator Interaction that occurs in many rotating disk-like parts of turbomachinery such as compressors, hydraulic runners or alternators is presented. The dynamic behavior of the rotating disk due to this excitation is deduced. For the experimental analysis a test rig has been developed. It consists of a stainless steel disk (r = 198 mm and h = 8 mm) connected to a variable speed motor. Excitation and response are measured from the rotating system. For the rotating excitation four piezoelectric patches have been used. Calibrating the piezoelectric patches in amplitude and phase, different rotating excitation patterns are applied on the rotating disk in air and in water. Results show the feasibility of using PZT to control the response of the disk due to a rotor-stator interaction. PMID:25004151

Feasibility of using PZT actuators to study the dynamic behavior of a rotating disk due to rotor-stator interaction.

PubMed

Presas, Alexandre; Egusquiza, Eduard; Valero, Carme; Valentin, David; Seidel, Ulrich

2014-07-07

In this paper, PZT actuators are used to study the dynamic behavior of a rotating disk structure due to rotor-stator interaction excitation. The disk is studied with two different surrounding fluids-air and water. The study has been performed analytically and validated experimentally. For the theoretical analysis, the natural frequencies and the associated mode shapes of the rotating disk in air and water are obtained with the Kirchhoff-Love thin plate theory coupled with the interaction with the surrounding fluid. A model for the Rotor Stator Interaction that occurs in many rotating disk-like parts of turbomachinery such as compressors, hydraulic runners or alternators is presented. The dynamic behavior of the rotating disk due to this excitation is deduced. For the experimental analysis a test rig has been developed. It consists of a stainless steel disk (r = 198 mm and h = 8 mm) connected to a variable speed motor. Excitation and response are measured from the rotating system. For the rotating excitation four piezoelectric patches have been used. Calibrating the piezoelectric patches in amplitude and phase, different rotating excitation patterns are applied on the rotating disk in air and in water. Results show the feasibility of using PZT to control the response of the disk due to a rotor-stator interaction.

Punching influence on magnetic properties of the stator teeth of an induction motor

NASA Astrophysics Data System (ADS)

Kedous-Lebouc, A.; Cornut, B.; Perrier, J. C.; Manfé, Ph.; Chevalier, Th.

2003-01-01

In order to study the effects of punching of electrical steel sheets, a suitable geometrical structure able to characterize the stator teeth behavior of an induction motor is proposed and validated. The influence of the punching on a fully processed M330-65A is then characterized. A spectacular degradation of loss and B( H) curves is observed. This leads to a perceptible increase of the no-load machine current.

Single-stage evaluation of highly-loaded high-Mach-number compressor stages 5. Data and performance of baseline, corner-blow wall suction and combined corner blow wall suction stator

NASA Technical Reports Server (NTRS)

Nikkanen, J. P.; Brooky, J. P.

1972-01-01

A single-stage compressor with a rotor tip speed of 1600 ft/sec and a 0.5 hub tip ratio was used to investigate the effects of several stator endwall treatment methods on stage range and performance. These endwall treatment methods consisted of stator corner-blow, annular wall suction upstream of stator leading edge, and combined corner-blow and annular wall suction. The overall stage performance with corner blow was essentially the same as the baseline performance. The performance for the annular wall suction and the combined corner-blow and wall suction showed a reduction in peak efficiency of 2.5 percentage points compared to the baseline data.

Bio-inspired piezoelectric linear motor driven by a single-phase harmonic wave with an asymmetric stator.

PubMed

Pan, Qiaosheng; Miao, Enming; Wu, Bingxuan; Chen, Weikang; Lei, Xiujun; He, Liangguo

2017-07-01

A novel, bio-inspired, single-phase driven piezoelectric linear motor (PLM) using an asymmetric stator was designed, fabricated, and tested to avoid mode degeneracy and to simplify the drive mechanism of a piezoelectric motor. A piezoelectric transducer composed of two piezoelectric stacks and a displacement amplifier was used as the driving element of the PLM. Two simple and specially designed claws performed elliptical motion. A numerical simulation was performed to design the stator and determine the feasibility of the design mechanism of the PLM. Moreover, an experimental setup was built to validate the working principles, as well as to evaluate the performance, of the PLM. The prototype motor outputs a no-load speed of 233.7 mm/s at a voltage of 180 V p-p and a maximum thrust force of 2.3 N under a preload of 10 N. This study verified the feasibility of the proposed design and provided a method to simplify the driving harmonic signal and structure of PLMs.

Advanced single permanent magnet axipolar ironless stator ac motor for electric passenger vehicles

NASA Technical Reports Server (NTRS)

Beauchamp, E. D.; Hadfield, J. R.; Wuertz, K. L.

1983-01-01

A program was conducted to design and develop an advanced-concept motor specifically created for propulsion of electric vehicles with increased range, reduced energy consumption, and reduced life-cycle costs in comparison with conventional systems. The motor developed is a brushless, dc, rare-earth cobalt, permanent magnet, axial air gap inductor machine that uses an ironless stator. Air cooling is inherent provided by the centrifugal-fan action of the rotor poles. An extensive design phase was conducted, which included analysis of the system performance versus the SAE J227a(D) driving cycle. A proof-of-principle model was developed and tested, and a functional model was developed and tested. Full generator-level testing was conducted on the functional model, recording electromagnetic, thermal, aerodynamic, and acoustic noise data. The machine demonstrated 20.3 kW output at 1466 rad/s and 160 dc. The novel ironless stator demonstated the capability to continuously operate at peak current. The projected system performance based on the use of a transistor inverter is 23.6 kW output power at 1466 rad/s and 83.3 percent efficiency. Design areas of concern regarding electric vehicle applications include the inherently high windage loss and rotor inertia.

Preparation of emulsions by rotor-stator homogenizer and ultrasonic cavitation for the cosmeceutical industry.

PubMed

Han, Ng Sook; Basri, Mahiran; Abd Rahman, Mohd Basyaruddin; Abd Rahman, Raja Noor Zaliha Raja; Salleh, Abu Bakar; Ismail, Zahariah

2012-01-01

Oil-in-water (O/W) nanoemulsions play an important key role in transporting bioactive compounds into a range of cosmeceutical products to the skin. Small droplet sizes have an inherent stability against creaming, sedimentation, flocculation, and coalescence. O/W emulsions varying in manufacturing process were prepared. The preparation and characterization of O/W nanoemulsions with average diameters of as low as 62.99 nm from palm oil esters were carried out. This was achieved using rotor-stator homogenizer and ultrasonic cavitation. Ultrasonic cell was utilized for the emulsification of palm oil esters and water in the presence of mixed surfactants, Tween 80 and Span 80 emulsions with a mean droplet size of 62.99 nm and zeta potential value at -37.8 mV. Results were comparable with emulsions prepared with rotor-stator homogenizer operated at 6000 rpm for 5 min. The stability of the emulsions was evaluated through rheology measurement properties. This included non-Newtonian viscosity, elastic modulus G', and loss modulus G″. A highly stable emulsion was prepared using ultrasonic cavitation comprising a very small particle size with higher zeta potential value and G' > G″ demonstrating gel-like behavior.

Numerical Investigation of Compressor Non-Synchronous Vibration with Full Annulus Rotor-Stator Interaction

NASA Astrophysics Data System (ADS)

Espinal, Daniel

The objective of this research is to investigate and confirm the periodicity of the Non-Synchronous Vibration (NSV) mechanism of a GE axial compressor with a full-annulus simulation. A second objective is to develop a high fidelity single-passage tool with time-accurate unsteady capabilities able to capture rotor-stator interactions and NSV excitation response. A high fidelity methodology for axial turbomachinery simulation is developed using the low diffusion shock-capturing Riemann solver with high order schemes, the Spalart-Allmaras turbulence closure model, the fully conservative unsteady sliding BC for rotor-stator interaction with extension to full-annulus and single-passage configurations, and the phase lag boundary conditions applied to rotor-stator interface and circumferential BC. A URANS solver is used and captures the NSV flow excitation frequency of 2439 Hz, which agrees reasonably well with the measured NSV frequency of 2600 Hz from strain gage test data. It is observed that the circumferentially traveling vortex formed in the vicinity of the rotor tip propagates at the speed of a non-engine order frequency and causes the NSV. The vortex travels along the suction surface of the blade and crosses the passage outlet near blade trailing edge. Such a vortex motion trajectory repeats in each blade passage and generates two low pressure regions due to the vortex core positions, one at the leading edge and one at the trailing edge, both are oscillating due to the vortex coming and leaving. These two low pressure regions create a pair of coupling forces that generates a torsion moment causing NSV. The full-annulus simulation shows that the circumferentially traveling vortex has fairly periodical behavior and is a full annulus structure. Also, frequencies below the NSV excitation frequency of 2439 Hz with large amplitudes in response to flow-separation related phenomena are present. This behavior is consistent with experimental measurements. For

On the relation between friction losses and pressure pulsations caused by Rotor Stator interaction on the Francis-99 turbine

NASA Astrophysics Data System (ADS)

Østby, Petter T. K.; Tore Billdal, Jan; Haugen, Bjørn; Dahlhaug, Ole Gunnar

2017-01-01

High head Francis runners are subject to pressure pulsations caused by rotor stator interaction. To ensure safe operation of such turbines, it is important to be able to predict these pulsations. For turbine manufacturers it is often a dilemma whether to perform very advanced and time consuming CFD calculations or to rely on simpler calculations to save development time. This paper tries to evaluate simplifications of the CFD model while still capturing the RSI phenomena and ensuring that the calculation does not underpredict the pressure amplitudes. The effects which turbulence modeling, wall friction, viscosity and mesh have on the pressure amplitudes will be investigated along with time savings with each simplification. The hypothesis is that rotor stator interaction is manly driven by inviscid flow and can therefore be modeled by the Euler equations.

Comparison of Computational Aeroacoustics Prediction of Acoustic Transmission Through a 3D Stator With Experiment

NASA Technical Reports Server (NTRS)

Hixon, Ray; Envia, Edmane; Dahl, Milo; Sutliff, Daniel L.

2014-01-01

In this paper, numerical predictions of acoustic transmission through a 3D stator obtained using the NASA BASS code are compared with experimentally measured data. The influence of vane count and stagger as well as frequency and mode order on the transmission loss is investigated. The data-theory comparisons indicate that BASS can predict all the important trends observed in the experimental data.

Comparison of Computational Aeroacoustics Prediction of Acoustic Transmission Through a 3D Stator with Experiment

NASA Technical Reports Server (NTRS)

Hixon, Ray; Envia, Edmane; Dahl, Milo; Sutliff, Daniel

2014-01-01

In this paper, numerical predictions of acoustic transmission through a 3D stator obtained using the NASA BASS code are compared with experimentally measured data. The influence of vane count and stagger as well as frequency and mode order on the transmission loss is investigated. The data-theory comparisons indicate that BASS can predict all the important trends observed in the experimental data.

Experimental Characterization and Modeling of Thermal Contact Resistance of Electric Machine Stator-to-Cooling Jacket Interface Under Interference Fit Loading

DOE PAGES

Cousineau, Justine Emily; Bennion, Kevin S.; Chieduko, Victor; ...

2018-05-08

Cooling of electric machines is a key to increasing power density and improving reliability. This paper focuses on the design of a machine using a cooling jacket wrapped around the stator. The thermal contact resistance (TCR) between the electric machine stator and cooling jacket is a significant factor in overall performance and is not well characterized. This interface is typically an interference fit subject to compressive pressure exceeding 5 MPa. An experimental investigation of this interface was carried out using a thermal transmittance setup using pressures between 5 and 10 MPa. Furthermore, the results were compared to currently available modelsmore » for contact resistance, and one model was adapted for prediction of TCR in future motor designs.« less

Experimental Characterization and Modeling of Thermal Contact Resistance of Electric Machine Stator-to-Cooling Jacket Interface Under Interference Fit Loading

DOE Office of Scientific and Technical Information (OSTI.GOV)

Cousineau, Justine Emily; Bennion, Kevin S.; Chieduko, Victor

Cooling of electric machines is a key to increasing power density and improving reliability. This paper focuses on the design of a machine using a cooling jacket wrapped around the stator. The thermal contact resistance (TCR) between the electric machine stator and cooling jacket is a significant factor in overall performance and is not well characterized. This interface is typically an interference fit subject to compressive pressure exceeding 5 MPa. An experimental investigation of this interface was carried out using a thermal transmittance setup using pressures between 5 and 10 MPa. Furthermore, the results were compared to currently available modelsmore » for contact resistance, and one model was adapted for prediction of TCR in future motor designs.« less

Large scale motions of multiple limit-cycle high Reynolds number annular and toroidal rotor/stator cavities

NASA Astrophysics Data System (ADS)

Bridel-Bertomeu, Thibault; Gicquel, L. Y. M.; Staffelbach, G.

2017-06-01

Rotating cavity flows are essential components of industrial applications but their dynamics are still not fully understood when it comes to the relation between the fluid organization and monitored pressure fluctuations. From computer hard-drives to turbo-pumps of space launchers, designed devices often produce flow oscillations that can either destroy the component prematurely or produce too much noise. In such a context, large scale dynamics of high Reynolds number rotor/stator cavities need better understanding especially at the flow limit-cycle or associated statistically stationary state. In particular, the influence of curvature as well as cavity aspect ratio on the large scale organization and flow stability at a fixed rotating disc Reynolds number is fundamental. To probe such flows, wall-resolved large eddy simulation is applied to two different rotor/stator cylindrical cavities and one annular cavity. Validation of the predictions proves the method to be suited and to capture the disc boundary layer patterns reported in the literature. It is then shown that in complement to these disc boundary layer analyses, at the limit-cycle the rotating flows exhibit characteristic patterns at mid-height in the homogeneous core pointing the importance of large scale features. Indeed, dynamic modal decomposition reveals that the entire flow dynamics are driven by only a handful of atomic modes whose combination links the oscillatory patterns observed in the boundary layers as well as in the core of the cavity. These fluctuations form macro-structures, born in the unstable stator boundary layer and extending through the homogeneous inviscid core to the rotating disc boundary layer, causing its instability under some conditions. More importantly, the macro-structures significantly differ depending on the configuration pointing the need for deeper understanding of the influence of geometrical parameters as well as operating conditions.

Single-stage experimental evaluation of tandem-airfoil rotor and stator blading for compressors. Part 3: Data and performance for stage C

NASA Technical Reports Server (NTRS)

Brent, J. A.; Clemmons, D.

1972-01-01

Stage C, comprised of tandem-airfoil rotor C and tandem-airfoil stator B, was designed and tested to establish performance data for comparison with the performance of conventional single-airfoil blading. Velocity diagrams and blade leading and trailing edge metal angles selected for the conventional rotor and stator blading were used in the design of the tandem blading. The rotor had an inlet hub/tip ratio of 0.8 and a design tip velocity of 757 ft/sec. At design equivalent rotor speed, rotor C achieved a maximum adiabatic efficiency of 91.8% at a pressure ratio of 1.31. The stage maximum adiabatic efficiency was 86.5% at a pressure ratio of 1.31.

Routes to turbulence in the rotating disk boundary-layer of a rotor-stator cavity

NASA Astrophysics Data System (ADS)

Yim, Eunok; Serre, Eric; Martinand, Denis; Chomaz, Jean-Marc

2016-11-01

The rotating disk is an important classical problem, due to the similarities between the 3D boundary layers on a disk and a swept aircraft wing. It is nowadays admitted that a direct transition to turbulence may exist through a steep-fronted nonlinear global mode located at the boundary between the locally connectively and absolutely unstable regions (Pier 2003; Viaud et al. 2008, 2011; Imayama et al. 2014 and others). However, recent studies (Healey 2010; Harris et al. 2012; Imayama et al. 2013) suggest that there may be an alternative route starting at lower critical Reynolds number, based on convective travelling waves but this scenario is still not fully validated and proven. To better characterize such transition, direct numerical simulations are performed in a closed cylindrical rotor-stator cavity (without hub) up to Re = O (105) . All boundaries are no slip and for the stable region around the rotation axis prevents the disturbances coming from the very unstable stator boundary to disturb the rotor boundary layer. Different transition scenarii to turbulence are investigated when the rotor boundary layer is forced at different positions and forcing amplitude. The associated dynamics of coherent structures in various flow regions are also investigated when increasing Re .

Compact piezoelectric micromotor with a single bulk lead zirconate titanate stator

NASA Astrophysics Data System (ADS)

Yan, Liang; Lan, Hua; Jiao, Zongxia; Chen, Chin-Yin; Chen, I.-Ming

2013-04-01

The advance of micro/nanotechnology promotes the development of micromotors in recent years. In this article, a compact piezoelectric ultrasonic micromotor with a single bulk lead zirconate titanate stator is proposed. A traveling wave is generated by superposition of bending modes with 90° phase difference excited by d15 inverse piezoelectric effects. The operating principle simplifies the system structure significantly, and provides a miniaturization solution. A research prototype with the size of 0.75× 0.75×1.55 mm is developed. It can produce start-up torque of 0.27μNmand maximum speed of 2760 r/min at 14RMS.

Turbine stator vane segment having internal cooling circuits

DOEpatents

Jones, Raymond Joseph; Burns, James Lee; Bojappa, Parvangada Ganapathy; Jones, Schotsch Margaret

2003-01-01

A turbine stator vane includes outer and inner walls each having outer and inner chambers and a vane extending between the outer and inner walls. The vane includes first, second, third, fourth and fifth cavities for flowing a cooling medium. The cooling medium enters the outer chamber of the outer wall, flows through an impingement plate for impingement cooling of the outer band wall defining in part the hot gas path and through openings in the first, second and fourth cavities for flow radially inwardly, cooling the vane. The spent cooling medium flows into the inner wall and inner chamber for flow through an impingement plate radially outwardly to cool the inner wall. The spent cooling medium flows through the third cavity for egress from the turbine vane segment from the outer wall. The first, second or third cavities contain inserts having impingement openings for impingement cooling of the vane walls. The fifth cavity provides air cooling for the trailing edge.

An improved low-voltage ride-through performance of DFIG based wind plant using stator dynamic composite fault current limiter.

PubMed

Gayen, P K; Chatterjee, D; Goswami, S K

2016-05-01

In this paper, an enhanced low-voltage ride-through (LVRT) performance of a grid connected doubly fed induction generator (DFIG) has been presented with the usage of stator dynamic composite fault current limiter (SDCFCL). This protection circuit comprises of a suitable series resistor-inductor combination and parallel bidirectional semiconductor switch. The SDCFCL facilitates double benefits such as reduction of rotor induced open circuit voltage due to increased value of stator total inductance and concurrent increase of rotor impedance. Both effects will limit rotor circuit over current and over voltage situation more secured way in comparison to the conventional scheme like the dynamic rotor current limiter (RCL) during any type of fault situation. The proposed concept is validated through the simulation study of the grid integrated 2.0MW DFIG. Copyright © 2016 ISA. Published by Elsevier Ltd. All rights reserved.

Novel model of stator design to reduce the mass of superconducting generators

NASA Astrophysics Data System (ADS)

Kails, Kevin; Li, Quan; Mueller, Markus

2018-05-01

High temperature superconductors (HTS), with much higher current density than conventional copper wires, make it feasible to develop very powerful and compact power generators. Thus, they are considered as one promising solution for large (10 + MW) direct-drive offshore wind turbines due to their low tower head mass. However, most HTS generator designs are based on a radial topology, which requires an excessive amount of HTS material and suffers from cooling and reliability issues. Axial flux machines on the other hand offer higher torque/volume ratios than the radial machines, which makes them an attractive option where space and transportation becomes an issue. However, their disadvantage is heavy structural mass. In this paper a novel stator design is introduced for HTS axial flux machines which enables a reduction in their structural mass. The stator is for the first time designed with a 45° angle that deviates the air gap closing forces into the vertical direction reducing the axial forces. The reduced axial forces improve the structural stability and consequently simplify their structural design. The novel methodology was then validated through an existing design of the HTS axial flux machine achieving a ∼10% mass reduction from 126 tonnes down to 115 tonnes. In addition, the air gap flux density increases due to the new claw pole shapes improving its power density from 53.19 to 61.90 W kg‑1. It is expected that the HTS axial flux machines designed with the new methodology offer a competitive advantage over other proposed superconducting generator designs in terms of cost, reliability and power density.

Laser Doppler, velocimeter system for turbine stator cascade studies and analysis of statistical biasing errors

NASA Technical Reports Server (NTRS)

Seasholtz, R. G.

1977-01-01

A laser Doppler velocimeter (LDV) built for use in the Lewis Research Center's turbine stator cascade facilities is described. The signal processing and self contained data processing are based on a computing counter. A procedure is given for mode matching the laser to the probe volume. An analysis is presented of biasing errors that were observed in turbulent flow when the mean flow was not normal to the fringes.

A nickel base alloy, NASA WAZ-16, with potential for gas turbine stator vane application

NASA Technical Reports Server (NTRS)

Waters, W. J.; Freche, J. C.

1974-01-01

A nickel-base superalloy based on the nickel-aluminum-tungsten system designated WAZ-16 was developed for high strength in the 1095 C (2000 F) to 1205 C (2200 F) range. Its tensile strength at the latter temperature is approximately 186 MN/m2 (27,000 psi). The combination of properties of the alloy suggest that it has potential as a stator vane material in advanced gas turbine engines.

Impulsive Injection for Compressor Stator Separation Control

NASA Technical Reports Server (NTRS)

Culley, Dennis E.; Braunscheidel, Edward P.; Bright, Michelle M.

2005-01-01

Flow control using impulsive injection from the suction surface of a stator vane has been applied in a low speed axial compressor. Impulsive injection is shown to significantly reduce separation relative to steady injection for vanes that were induced to separate by an increase in vane stagger angle of 4 degrees. Injected flow was applied to the airfoil suction surface using spanwise slots pitched in the streamwise direction. Injection was limited to the near-hub region, from 10 to 36 percent of span, to affect the dominant loss due to hub leakage flow. Actuation was provided externally using high-speed solenoid valves closely coupled to the vane tip. Variations in injected mass, frequency, and duty cycle are explored. The local corrected total pressure loss across the vane at the lower span region was reduced by over 20 percent. Additionally, low momentum fluid migrating from the hub region toward the tip was effectively suppressed resulting in an overall benefit which reduced corrected area averaged loss through the passage by 4 percent. The injection mass fraction used for impulsive actuation was typically less than 0.1 percent of the compressor through flow.

Advanced simulation model for IPM motor drive with considering phase voltage and stator inductance

NASA Astrophysics Data System (ADS)

Lee, Dong-Myung; Park, Hyun-Jong; Lee, Ju

2016-10-01

This paper proposes an advanced simulation model of driving system for Interior Permanent Magnet (IPM) BrushLess Direct Current (BLDC) motors driven by 120-degree conduction method (two-phase conduction method, TPCM) that is widely used for sensorless control of BLDC motors. BLDC motors can be classified as SPM (Surface mounted Permanent Magnet) and IPM motors. Simulation model of driving system with SPM motors is simple due to the constant stator inductance regardless of the rotor position. Simulation models of SPM motor driving system have been proposed in many researches. On the other hand, simulation models for IPM driving system by graphic-based simulation tool such as Matlab/Simulink have not been proposed. Simulation study about driving system of IPMs with TPCM is complex because stator inductances of IPM vary with the rotor position, as permanent magnets are embedded in the rotor. To develop sensorless scheme or improve control performance, development of control algorithm through simulation study is essential, and the simulation model that accurately reflects the characteristic of IPM is required. Therefore, this paper presents the advanced simulation model of IPM driving system, which takes into account the unique characteristic of IPM due to the position-dependent inductances. The validity of the proposed simulation model is validated by comparison to experimental and simulation results using IPM with TPCM control scheme.

Simulink(Trademark) Controller for a Reluctance Motor With a Four-Pole Rotor and 36-Tooth Stator

NASA Technical Reports Server (NTRS)

Morrison, Carlos R.; Provenza, Andrew J.

2017-01-01

NASA Glenn Research Center has developed a Simulink(Trademark) controller logic for driving a room temperature, 36-teeth stator, four-pole rotor reluctance motor. The Simulink logic was extracted from an existing C++ motor controller that was previously employed to achieve a rotor speed of 3000 rpm. The Simulink controller has additional logic refinements that were not available in past C++ controller, such as the per rev logic component and its frequency filter. The filter provides a more accurate reading of the rotor input signals. The controller is versatile, and with slight modifications, can be used to drive other reluctance motor types incorporating dissimilar stator rotor pole combinations. The original C++ controller was designed with the goal (after appropriate modification) of controlling a future superconducting motor. This superconducting motor will be employed as a test bed for developing other superconducting aviation propulsion motors envisioned for future turbo-electric aircrafts. The Simulink results presented in this paper were generated from simulated rotor inputs. However, in an actual application, these simulated inputs are to be replaced by actual proximity probe signals emanating from D-Space hardware inputs.

Coupling of Low Speed Fan Stator Vane Unsteady Pressures to Duct Modes: Measured versus Predicted

NASA Technical Reports Server (NTRS)

Sutliff, Daniel L.; Heidelberg, Laurence J.; Envia, Edmane

1999-01-01

Uniform-flow annular-duct Green's functions are the essential elements of the classical acoustic analogy approach to the problem of computing the noise generated by rotor-stator interaction inside the fan duct. This paper investigates the accuracy of this class of Green's functions for predicting the duct noise levels when measured stator vane unsteady surface pressures are used as input to the theoretical formulation. The accuracy of the method is evaluated by comparing the predicted and measured acoustic power levels for the NASA 48 inch low speed Active Noise Control Fan. The unsteady surface pressures are measured,by an array of microphones imbedded in the suction and pressure sides of a single vane, while the duct mode levels are measured using a rotating rake system installed in the inlet and exhaust sections of the fan duct. The predicted levels are computed using properly weighted integrals of measured surface pressure distribution. The data-theory comparisons are generally quite good particularly when the mode cut-off criterion is carefully interpreted. This suggests that, at least for low speed fans, the uniform-flow annular-duct Green's function theory can be reliably used for prediction of duct mode levels if the cascade surface pressure distribution is accurately known.

Acoustic Scattering by Three-Dimensional Stators and Rotors Using the SOURCE3D Code. Volume 2; Scattering Plots

NASA Technical Reports Server (NTRS)

Meyer, Harold D.

1999-01-01

This second volume of Acoustic Scattering by Three-Dimensional Stators and Rotors Using the SOURCE3D Code provides the scattering plots referenced by Volume 1. There are 648 plots. Half are for the 8750 rpm "high speed" operating condition and the other half are for the 7031 rpm "mid speed" operating condition.

Rotor-stator molecular crystals of fullerenes with cubane.

PubMed

Pekker, Sándor; Kováts, Eva; Oszlányi, Gábor; Bényei, Gyula; Klupp, Gyöngyi; Bortel, Gábor; Jalsovszky, István; Jakab, Emma; Borondics, Ferenc; Kamarás, Katalin; Bokor, Mónika; Kriza, György; Tompa, Kálmán; Faigel, Gyula

2005-10-01

Cubane (C8H8) and fullerene (C60) are famous cage molecules with shapes of platonic or archimedean solids. Their remarkable chemical and solid-state properties have induced great scientific interest. Both materials form polymorphic crystals of molecules with variable orientational ordering. The idea of intercalating fullerene with cubane was raised several years ago but no attempts at preparation have been reported. Here we show that C60 and similarly C70 form high-symmetry molecular crystals with cubane owing to topological molecular recognition between the convex surface of fullerenes and the concave cubane. Static cubane occupies the octahedral voids of the face-centred-cubic structures and acts as a bearing between the rotating fullerene molecules. The smooth contact of the rotor and stator molecules decreases significantly the temperature of orientational ordering. These materials have great topochemical importance: at elevated temperatures they transform to high-stability covalent derivatives although preserving their crystalline appearance. The size-dependent molecular recognition promises selective formation of related structures with higher fullerenes and/or substituted cubanes.

Numerical solutions of 2-D multi-stage rotor/stator unsteady flow interactions

NASA Astrophysics Data System (ADS)

Yang, R.-J.; Lin, S.-J.

1991-01-01

The Rai method of single-stage rotor/stator flow interaction is extended to handle multistage configurations. In this study, a two-dimensional Navier-Stokes multi-zone approach was used to investigate unsteady flow interactions within two multistage axial turbines. The governing equations are solved by an iterative, factored, implicit finite-difference, upwind algorithm. Numerical accuracy is checked by investigating the effect of time step size, the effect of subiteration in the Newton-Raphson technique, and the effect of full viscous versus thin-layer approximation. Computer results compared well with experimental data. Unsteady flow interactions, wake cutting, and the associated evolution of vortical entities are discussed.

Comparison of steady and unsteady secondary flows in a turbine stator cascade

NASA Technical Reports Server (NTRS)

Hebert, Gregory J.; Tiederman, William G.

1989-01-01

The effect of periodic rotor wakes on the secondary flow structure in a turbine stator cascade was investigated. A mechanism simulated the wakes shed from rotor blades by passing cylindrical rods across the inlet to a linear cascade installed in a recirculating water flow loop. Velocity measurements showed a passage vortex, similar to that seen in steady flow, during the time associated with undisturbed fluid. However, as the rotor wake passed through the blade row, a large crossflow toward the suction surface was observed in the midspan region. This caused the development of two large areas of circulation between the midspan and endwall regions, significantly distorting and weakening the passage vortices.

Numerical investigation of the bowed stator effects in a transonic fan at low Reynolds number

NASA Astrophysics Data System (ADS)

Huang, Enliang; Zhao, Shengfeng; Gong, Jianbo; Lu, Xingen; Zhu, Junqiang

2017-02-01

The performance of fan stage in a small turbofan engines is significantly affected at high-altitude low Reynolds number. In order to examine the effect of low Reynolds number on the fan stage, 3D numerical simulation method was employed to analyse the performance variations and the underlying flow structure in the fan stage. For the sake of decreasing the influence of low Reynolds number, the different bowed stator airfoils were redesigned and the effect of the modified design was evaluated.

A variable-mode stator consequent pole memory machine

NASA Astrophysics Data System (ADS)

Yang, Hui; Lyu, Shukang; Lin, Heyun; Zhu, Z. Q.

2018-05-01

In this paper, a variable-mode concept is proposed for the speed range extension of a stator-consequent-pole memory machine (SCPMM). An integrated permanent magnet (PM) and electrically excited control scheme is utilized to simplify the flux-weakening control instead of relatively complicated continuous PM magnetization control. Due to the nature of memory machine, the magnetization state of low coercive force (LCF) magnets can be easily changed by applying either a positive or negative current pulse. Therefore, the number of PM poles may be changed to satisfy the specific performance requirement under different speed ranges, i.e. the machine with all PM poles can offer high torque output while that with half PM poles provides wide constant power range. In addition, the SCPMM with non-magnetized PMs can be considered as a dual-three phase electrically excited reluctance machine, which can be fed by an open-winding based dual inverters that provide direct current (DC) bias excitation to further extend the speed range. The effectiveness of the proposed variable-mode operation for extending its operating region and improving the system reliability is verified by both finite element analysis (FEA) and experiments.

Component Performance Investigation of J71 Experimental Turbine. Part 2; Internal-Flow Conditions with 97-Percent-Design Stator Areas

NASA Technical Reports Server (NTRS)

Rebeske, John J., Jr.; Petrash, Donald A.

1956-01-01

An experimental investigation of the internal-flow conditions of a J71 experimental turbine equipped with 97-percent-design stator areas was conducted at equivalent design speed and near equivalent design work. The results of the investigation indicate that the stage work distribution closely approximates design, the actual distribution being 44.1, 33.4, and 22.5 percent for the first, second, and third stages, respectively. The first-, second-, and third-stage efficiencies were 0.894, 0.858, and 0.792, respectively. The first and second stages exhibited loss regions near the hub and tip at the rotor blade outlets. The hub loss region is attributed to stator secondary flows, and a contributing factor to the tip loss region may be the high design diffusion on the rotor blade suction surface near the tip. The loss in the third stage is appreciably greater than that in the first or second stage. The fact that the third rotor is unshrouded and has a nominal tip clearance of 0.120 inch may contribute to the higher loss in the tip region of the third stage.

The effects of inlet turbulence and rotor/stator interactions on the aerodynamics and heat transfer of a large-scale rotating turbine model, volume 1

NASA Technical Reports Server (NTRS)

Dring, R. P.; Blair, M. F.; Joslyn, H. D.; Power, G. D.; Verdon, J. M.

1987-01-01

A combined experimental and analytical program was conducted to examine the effects of inlet turbulence on airfoil heat transfer. Heat transfer measurements were obtained using low conductivity airfoils with miniature thermocouples welded to a thin, electrically heated surface skin. Heat transfer data were acquired for various combinations of low or high inlet turbulence intensity, flow coefficient (incidence), first-stator/rotor axial spacing, Reynolds number, and relative circumferential position of the first and second stators. Aerodynamic measurements include distributions of the mean and fluctuating velocities at the turbine inlet and, for each airfoil row, midspan airfoil surface pressures and circumferential distributions of the downstream steady state pressures and fluctuating velocities. Analytical results include airfoil heat transfer predictions and a examination of solutions of the unstead boundary layer equipment.

Stator and Rotor Flux Based Deadbeat Direct Torque Control of Induction Machines

NASA Technical Reports Server (NTRS)

Kenny, Barbara H.; Lorenz, Robert D.

2001-01-01

A new, deadbeat type of direct torque control is proposed, analyzed, and experimentally verified in this paper. The control is based on stator and rotor flux as state variables. This choice of state variables allows a graphical representation which is transparent and insightful. The graphical solution shows the effects of realistic considerations such as voltage and current limits. A position and speed sensorless implementation of the control, based on the self-sensing signal injection technique, is also demonstrated experimentally for low speed operation. The paper first develops the new, deadbeat DTC methodology and graphical representation of the new algorithm. It then evaluates feasibility via simulation and experimentally demonstrates performance of the new method with a laboratory prototype including the sensorless methods.

FEM analysis of an single stator dual PM rotors axial synchronous machine

NASA Astrophysics Data System (ADS)

Tutelea, L. N.; Deaconu, S. I.; Popa, G. N.

2017-01-01

The actual e - continuously variable transmission (e-CVT) solution for the parallel Hybrid Electric Vehicle (HEV) requires two electric machines, two inverters, and a planetary gear. A distinct electric generator and a propulsion electric motor, both with full power converters, are typical for a series HEV. In an effort to simplify the planetary-geared e-CVT for the parallel HEV or the series HEV we hereby propose to replace the basically two electric machines and their two power converters by a single, axial-air-gap, electric machine central stator, fed from a single PWM converter with dual frequency voltage output and two independent PM rotors. The proposed topologies, the magneto-motive force analysis and quasi 3D-FEM analysis are the core of the paper.

Stator and Rotor Flux Based Deadbeat Direct Torque Control of Induction Machines

NASA Technical Reports Server (NTRS)

Kenny, Barbara H.; Lorenz, Robert D.

2003-01-01

A new, deadbeat type of direct torque control is proposed, analyzed and experimentally verified in this paper. The control is based on stator and rotor flux as state variables. This choice of state variables allows a graphical representation which is transparent and insightful. The graphical solution shows the effects of realistic considerations such as voltage and current limits. A position and speed sensorless implementation of the control, based on the self-sensing signal injection technique, is also demonstrated experimentally for low speed operation. The paper first develops the new, deadbeat DTC methodology and graphical representation of the new algorithm. It then evaluates feasibility via simulation and experimentally demonstrates performance of the new method with a laboratory prototype including the sensorless methods.

MotI (DgrA) acts as a molecular clutch on the flagellar stator protein MotA in Bacillus subtilis

PubMed Central

Subramanian, Sundharraman; Gao, Xiaohui; Dann, Charles E.; Kearns, Daniel B.

2017-01-01

Stator elements consisting of MotA4MotB2 complexes are anchored to the cell wall, extend through the cell membrane, and interact with FliG in the cytoplasmic C ring rotor of the flagellum. The cytoplasmic loop of MotA undergoes proton-driven conformational changes that drive flagellar rotation. Functional regulators inhibit motility by either disengaging or jamming the stator–rotor interaction. Here we show that the YcgR homolog MotI (formerly DgrA) of Bacillus subtilis inhibits motility like a molecular clutch that disengages MotA. MotI-inhibited flagella rotated freely by Brownian motion, and suppressor mutations in MotA that were immune to MotI inhibition were located two residues downstream of the critical force generation site. The 3D structure of MotI bound to c-di-GMP was solved, and MotI-fluorescent fusions localized as transient MotA-dependent puncta at the membrane when induced at subinhibitory levels. Finally, subinhibitory levels of MotI expression resulted in incomplete inhibition and proportional decreases in swimming speed. We propose a model in which flagellar stators are disengaged and sequestered from the flagellar rotor when bound by MotI. PMID:29196522

Flow visualization study of the horseshoe vortex in a turbine stator cascade

NASA Technical Reports Server (NTRS)

Gaugler, R. E.; Russell, L. M.

1982-01-01

Flow visualization techniques were used to show the behavior of the horseshoe vortex in a large scale turbine stator cascade. Oil drops on the end wall surface flowed in response to local shear stresses, indicating the limiting flow streamlines at the surface. Smoke injected into the flow and photographed showed time averaged flow behavior. Neutrally bouyant helium filled soap bubbles followed the flow and showed up on photographs as streaks, indicating the paths followed by individual fluid particles. Preliminary attempts to control the vortex were made by injecting air through control jets drilled in the end wall near the vane leading edge. Seventeen different hole locations were tested, one at a time, and the effect of the control jets on the path follwed by smoke in the boundary layer was recorded photographically.

Numerical analysis of hydrodynamics in a rotor-stator reactor for biodiesel synthesis

NASA Astrophysics Data System (ADS)

Wen, Zhuqing; Petera, Jerzy

2016-06-01

A rotor-stator spinning disk reactor for intensified biodiesel synthesis is described and numerically simulated. The reactor consists of two flat disks, located coaxially and parallel to each other with a gap ranging from 0.1 mm to 0.2 mm between the disks. The upper disk is located on a rotating shaft while the lower disk is stationary. The feed liquids, triglycerides (TG) and methanol are introduced coaxially along the center line of rotating disk and stationary disk, respectively. Fluid hydrodynamics in the reactor for synthesis of biodiesel from TG and methanol in the presence of a sodium hydroxide catalyst are simulated, using convection-diffusion-reaction species transport model by the CFD software ANSYS©Fluent v. 13.0. The effects of upper disk's spinning speed, gap size and flow rates at inlets are evaluated.

Synthesis of Structurally Diverse Emissive Molecular Rotors with Four-Component Ugi Stators.

PubMed

García-González, Ma Carmen; Aguilar-Granda, Andrés; Zamudio-Medina, Angel; Miranda, Luis D; Rodríguez-Molina, Braulio

2018-03-02

The use of the multicomponent Ugi reaction to rapidly prepare a library of dumbbell-like molecular rotors is highlighted here. The synthetic strategy consisted of the atom-economic access to 15 bulky and structurally diverse iodinated stators, which were cross-coupled to the 1,4-diethynylphenylene rotator. From those experiments, up to six rotors 1a-c and 1l-n were obtained, with yields ranging from 35 to 69% per coupled C-C bond. In addition to the framework diversity, five of these compounds showed aggregate-enhanced emission properties thanks to their conjugated 1,4-bis(phenylethynyl)benzene cores, a property that rises by increasing the water fraction (f w ) in their THF solutions. The results highlight the significance of the diversity-oriented synthesis of rapid access to new molecular fluorescent rotors.

Como Lo Hago Yo: Tratamiento Quirurgico Del Mielomeningocele

PubMed Central

Portillo, Santiago

2014-01-01

En Argentina hay plan de fortificación con ácido fólico. Diagnostico prenatal no siempre es correcto. Cierre según técnica. Cerramos músculo. No favorecemos corpectomía temprana en casos de cifosis. Suturamos la plaqueta. Cerramos el plano muscular. Hidrocefalia: Válvula de derivación, generalmente dentro de los dos primeros meses. Ventriculostomía no está indicada. Chiari II. Laminectomia cervical alta. Siringomielia: Derivación desde la cavidad al peritoneo. PMID:24791219

Broadband Noise of Fans - With Unsteady Coupling Theory to Account for Rotor and Stator Reflection/Transmission Effects

NASA Technical Reports Server (NTRS)

Hanson, Donald B.

2001-01-01

This report examines the effects on broadband noise generation of unsteady coupling between a rotor and stator in the fan stage of a turbofan engine. Whereas previous acoustic analyses treated the blade rows as isolated cascades, the present work accounts for reflection and transmission effects at both blade rows by tracking the mode and frequency scattering of pressure and vortical waves. The fan stage is modeled in rectilinear geometry to take advantage of a previously existing unsteady cascade theory for 3D perturbation waves and thereby use a realistic 3D turbulence spectrum. In the analysis, it was found that the set of participating modes divides itself naturally into "independent mode subsets" that couple only among themselves and not to the other such subsets. This principle is the basis for the analysis and considerably reduces computational effort. It also provides a simple, accurate scheme for modal averaging for further efficiency. Computed results for a coupled fan stage are compared with calculations for isolated blade rows. It is found that coupling increases downstream noise by 2 to 4 dB. Upstream noise is lower for isolated cascades and is further reduced by including coupling effects. In comparison with test data, the increase in the upstream/downstream differential indicates that broadband noise from turbulent inflow at the stator dominates downstream noise but is not a significant contributor to upstream noise.

Expression, purification and biochemical characterization of the cytoplasmic loop of PomA, a stator component of the Na+ driven flagellar motor

PubMed Central

Abe-Yoshizumi, Rei; Kobayashi, Shiori; Gohara, Mizuki; Hayashi, Kokoro; Kojima, Chojiro; Kojima, Seiji; Sudo, Yuki; Asami, Yasuo; Homma, Michio

2013-01-01

Flagellar motors embedded in bacterial membranes are molecular machines powered by specific ion flows. Each motor is composed of a stator and a rotor and the interactions of those components are believed to generate the torque. Na+ influx through the PomA/PomB stator complex of Vibrio alginolyticus is coupled to torque generation and is speculated to trigger structural changes in the cytoplasmic domain of PomA that interacts with a rotor protein in the C-ring, FliG, to drive the rotation. In this study, we tried to overproduce the cytoplasmic loop of PomA (PomA-Loop), but it was insoluble. Thus, we made a fusion protein with a small soluble tag (GB1) which allowed us to express and characterize the recombinant protein. The structure of the PomA-Loop seems to be very elongated or has a loose tertiary structure. When the PomA-Loop protein was produced in E. coli, a slight dominant effect was observed on motility. We conclude that the cytoplasmic loop alone retains a certain function. PMID:27493537

Study on casing treatment and stator matching on multistage fan

NASA Astrophysics Data System (ADS)

Wu, Chuangliang; Yuan, Wei; Deng, Zhe

2017-10-01

Casing treatments are required for expanding the stall margin of multi-stage high-load turbofans designed with high blade-tip Mach numbers and high leakage flow. In the case of a low mass flow, the casing treatment effectively reduces the blockages caused by the leakage flow and enlarges the stall margin. However, in the case of a high mass flow, the casing treatment affects the overall flow capacity of the fan, the thrust when operating at the high speeds usually required by design-point specifications. Herein, we study a two-stage high-load fan with three-dimensional numerical simulations. We use the simulation results to propose a scheme that enlarges the stall margin of multistage high-load fans without sacrificing the flow capacity when operating with a large mass flow. Furthermore, a circumferential groove casing treatment is used and adjustments are made to the upstream stator angle to match the casing treatment. The stall margin is thus increased to 16.3%, with no reduction in the maximum mass flow rate or the design thrust performance.

Numerical analysis of hydrodynamics in a rotor-stator reactor for biodiesel synthesis

DOE Office of Scientific and Technical Information (OSTI.GOV)

Wen, Zhuqing; Petera, Jerzy

A rotor-stator spinning disk reactor for intensified biodiesel synthesis is described and numerically simulated. The reactor consists of two flat disks, located coaxially and parallel to each other with a gap ranging from 0.1 mm to 0.2 mm between the disks. The upper disk is located on a rotating shaft while the lower disk is stationary. The feed liquids, triglycerides (TG) and methanol are introduced coaxially along the center line of rotating disk and stationary disk, respectively. Fluid hydrodynamics in the reactor for synthesis of biodiesel from TG and methanol in the presence of a sodium hydroxide catalyst are simulated, using convection-diffusion-reactionmore » species transport model by the CFD software ANSYS©Fluent v. 13.0. The effects of upper disk’s spinning speed, gap size and flow rates at inlets are evaluated.« less

Sensorless speed detection of squirrel-cage induction machines using stator neutral point voltage harmonics

NASA Astrophysics Data System (ADS)

Petrovic, Goran; Kilic, Tomislav; Terzic, Bozo

2009-04-01

In this paper a sensorless speed detection method of induction squirrel-cage machines is presented. This method is based on frequency determination of the stator neutral point voltage primary slot harmonic, which is dependent on rotor speed. In order to prove method in steady state and dynamic conditions the simulation and experimental study was carried out. For theoretical investigation the mathematical model of squirrel cage induction machines, which takes into consideration actual geometry and windings layout, is used. Speed-related harmonics that arise from rotor slotting are analyzed using digital signal processing and DFT algorithm with Hanning window. The performance of the method is demonstrated over a wide range of load conditions.

Cold-air performance of a 15.41-cm-tip-diameter axial-flow power turbine with variable-area stator designed for a 75-kW automotive gas turbine engine

NASA Technical Reports Server (NTRS)

Mclallin, K. L.; Kofskey, M. G.; Wong, R. Y.

1982-01-01

An experimental evaluation of the aerodynamic performance of the axial flow, variable area stator power turbine stage for the Department of Energy upgraded automotive gas turbine engine was conducted in cold air. The interstage transition duct, the variable area stator, the rotor, and the exit diffuser were included in the evaluation of the turbine stage. The measured total blading efficiency was 0.096 less than the design value of 0.85. Large radial gradients in flow conditions were found at the exit of the interstage duct that adversely affected power turbine performance. Although power turbine efficiency was less than design, the turbine operating line corresponding to the steady state road load power curve was within 0.02 of the maximum available stage efficiency at any given speed.

Stator and Rotor Flux Based Deadbeat Direct Torque Control of Induction Machines. Revision 1

NASA Technical Reports Server (NTRS)

Kenny, Barbara H.; Lorenz, Robert D.

2002-01-01

A new, deadbeat type of direct torque control is proposed, analyzed, and experimentally verified in this paper. The control is based on stator and rotor flux as state variables. This choice of state variables allows a graphical representation which is transparent and insightful. The graphical solution shows the effects of realistic considerations such as voltage and current limits. A position and speed sensorless implementation of the control, based on the self-sensing signal injection technique, is also demonstrated experimentally for low speed operation. The paper first develops the new, deadbeat DTC methodology and graphical representation of the new algorithm. It then evaluates feasibility via simulation and experimentally demonstrates performance of the new method with a laboratory prototype including the sensorless methods.

Investigation of Hot Streak Migration and Film Cooling Effects on Heat Transfer in Rotor/Stator Interacting Flows. Report 1

DTIC Science & Technology

1992-04-01

I Investigation of Hot Streak Migration and Film Cooling Effects on Heat Transfer in Rotor/Stator Interacting Flows £ N00140-88-C-0677 - Report 1 00...performed ld*ch addresses the Issuas of mlti-blade count ratio s&ad three-dimensionality effects on the prediction of combu tr hot str"k migration in a...demnstrates tbe capabilty of the thro-dirnsioual procedure to cApture most of the flow physics associated with hot streak migration including the

Winding Schemes for Wide Constant Power Range of Double Stator Transverse Flux Machine

DOE Office of Scientific and Technical Information (OSTI.GOV)

Husain, Tausif; Hassan, Iftekhar; Sozer, Yilmaz

2015-05-01

Different ring winding schemes for double sided transverse flux machines are investigated in this paper for wide speed operation. The windings under investigation are based on two inverters used in parallel. At higher power applications this arrangement improves the drive efficiency. The new winding structure through manipulation of the end connection splits individual sets into two and connects the partitioned turns from individual stator sets in series. This configuration offers the flexibility of torque profiling and a greater flux weakening region. At low speeds and low torque only one winding set is capable of providing the required torque thus providingmore » greater fault tolerance. At higher speeds one set is dedicated to torque production and the other for flux control. The proposed method improves the machine efficiency and allows better flux weakening which is desirable for traction applications.« less

Effect of air gap variation on the performance of single stator single rotor axial flux permanent magnet generator

NASA Astrophysics Data System (ADS)

Kasim, Muhammad; Irasari, Pudji; Hikmawan, M. Fathul; Widiyanto, Puji; Wirtayasa, Ketut

2017-02-01

The axial flux permanent magnet generator (AFPMG) has been widely used especially for electricity generation. The effect of the air gap variation on the characteristic and performances of single rotor - single stator AFPMG has been described in this paper. Effect of air gap length on the magnetic flux distribution, starting torque and MMF has been investigated. The two dimensional finite element magnetic method has been deployed to model and simulated the characteristics of the machine which is based on the Maxwell equation. The analysis has been done for two different air gap lengths which were 2 mm and 4 mm using 2D FEMM 4.2 software at no load condition. The increasing of air gap length reduces the air-gap flux density. For air gap 2 mm, the maximum value of the flux density was 1.04 T while 0.73 T occured for air gap 4 mm.. Based on the experiment result, the increasing air gap also reduced the starting torque of the machine with 39.2 Nm for air gap 2 mm and this value decreased into 34.2 Nm when the air gap increased to 4 mm. Meanwhile, the MMF that was generated by AFPMG decreased around 22% at 50 Hz due to the reduction of magnetic flux induced on stator windings. Overall, the research result showed that the variation of air gap has significant effect on the machine characteristics.

EEMD-based wind turbine bearing failure detection using the generator stator current homopolar component

NASA Astrophysics Data System (ADS)

Amirat, Yassine; Choqueuse, Vincent; Benbouzid, Mohamed

2013-12-01

Failure detection has always been a demanding task in the electrical machines community; it has become more challenging in wind energy conversion systems because sustainability and viability of wind farms are highly dependent on the reduction of the operational and maintenance costs. Indeed the most efficient way of reducing these costs would be to continuously monitor the condition of these systems. This allows for early detection of the generator health degeneration, facilitating a proactive response, minimizing downtime, and maximizing productivity. This paper provides then an assessment of a failure detection techniques based on the homopolar component of the generator stator current and attempts to highlight the use of the ensemble empirical mode decomposition as a tool for failure detection in wind turbine generators for stationary and non-stationary cases.

Study of stator-vane fluctuating pressures in a turbofan engine for static and flight tests

NASA Technical Reports Server (NTRS)

Mueller, A. W.

1984-01-01

As part of a program to study the fan noise generated from turbofan engines, fluctuating surface pressures induced by fan-rotor wakes were measured on core- and bypass-stator outlet guide vanes of a modified JT15D-1 engine. Tests were conducted with the engine operating on an outdoor test stand and in flight. The amplitudes of pressures measured at fan-rotor blade-passage fundamental frequencies were generally higher and appeared less stable for the static tests than for the flight tests. Fluctuating pressures measured at the blade-passage frequency of the high-speed core compressor were interpreted to be acoustic; however, disturbance trace velocities for either the convected rotor wakes or acoustic pressures were difficult to interpret because of the complex environment.

Velocity surveys in a turbine stator annular-cascade facility using laser Doppler techniques. [flow measurement and flow characteristics

NASA Technical Reports Server (NTRS)

Goldman, L. J.; Seasholtz, R. G.; Mclallin, K. L.

1976-01-01

A laser Doppler velocimeter (LDV) was used to determine the flow conditions downstream of an annular cascade of stator blades operating at an exit critical velocity ratio of 0.87. Two modes of LDV operation (continuous scan and discrete point) were investigated. Conventional pressure probe measurements were also made for comparison with the LDV results. Biasing errors that occur in the LDV measurement of velocity components were also studied. In addition, the effect of pressure probe blockage on the flow conditions was determined with the LDV. Photographs and descriptions of the test equipment used are given.

Experimental Evaluation of Cermet Turbine Stator Blades for Use at Elevated Gas Temperatures

NASA Technical Reports Server (NTRS)

Chiarito, Patrick T.; Johnston, James R.

1959-01-01

The suitability of cermets for turbine stator blades of a modified turbojet engine was determined at an average turbine-inlet-gas temperature of 2000 F. Such an increase in temperature would yield a premium in thrust from a service engine. Because the cermet blades require no cooling, all the available compressor bleed air could be used to cool a turbine made from conventional ductile alloys. Cermet blades were first run in 100-hour endurance tests at normal gas temperatures in order to evaluate two methods for mounting them. The elevated gas-temperature test was then run using the method of support considered best for high-temperature operation. After 52 hours at 2000 F, one of the group of four cermet blades fractured probably because of end loads resulting from thermal distortion of the spacer band of the nozzle diaphragm. Improved design of a service engine would preclude this cause of premature failure.

The effects of inlet turbulence and rotor/stator interactions on the aerodynamics and heat transfer of a large-scale rotating turbine model. Part 4: Aerodynamic data tabulation

NASA Technical Reports Server (NTRS)

Dring, R. P.; Joslyn, H. D.; Blair, M. F.

1987-01-01

A combined experimental and analytical program was conducted to examine the effects of inlet turbulence and airfoil heat transfer. The experimental portion of the study was conducted in a large-scale (approx. 5X engine), ambient temperature, rotating turbine model configured in both single-stage and stage-and-a-half arrangements. Heat transfer measurements were obtained using low-conductivity airfoils with miniature thermocouples welded to a thin, electrically heated surface skin. Heat transfer data were acquired for various combinations of low or high inlet turbulence intensity, flow coefficient, first stator-rotor axial spacing, Reynolds number and relative circumferential position of the first and second stators. Aerodynamic measurements obtained include distributions of the mean and fluctuating velocities at the turbine inlet and, for each airfoil row, midspan airfoil surface pressures and circumferential distributions of the downstream steady state pressures and fluctuating velocities. Results include airfoil heat transfer predictions produced using existing 2-D boundary layer computation schemes and an examination of solutions of the unsteady boundary layer equations.

Single stage experimental evaluation of tandem-airfoil rotor and stator blading for compressors. Part 4: Data and performance for stage B

NASA Technical Reports Server (NTRS)

Brent, J. A.; Cheatham, J. G.

1973-01-01

Stage B, composed of tandem-airfoil rotor B and stator B, was tested with uniform inlet flow and with hub radial, tip radial and 90 degree one-per-revolution circumferential distortion of the inlet flow as part of an overall program to evaluate the effectiveness of tandem airfoils for increasing the design point loading capability and stable operating range of rotor and stator blading. The results of this series of tests provide overall performance and blade element data for evaluating: (1) the potential of tandem blading for extending the loading limit and stable operating range of a stage representative of a middle stage of an advanced high pressure compressor, (2) the effect of loading split between the two airfoils in tandem on the performance of tandem blading, and (3) the effects of inlet flow distortion on the stage performance. The rotor had an inlet hub/tip ratio of 0.8 and a design tip velocity of 757 ft/sec. With uniform inlet flow, rotor B achieved a maximum adiabatic efficiency of 88.4% at design equivalent rotor speed and a pressure ratio of 1.31. The stage maximum adiabatic efficiency at design equivalent rotor speed with uniform inlet flow was 82.5% at a pressure ratio of 1.28. Tip radial and circumferential distortion of the inlet flow caused substantial reductions in surge margin.

A conserved residue, PomB-F22, in the transmembrane segment of the flagellar stator complex, has a critical role in conducting ions and generating torque.

PubMed

Terauchi, Takashi; Terashima, Hiroyuki; Kojima, Seiji; Homma, Michio

2011-08-01

Bacterial flagellar motors exploit the electrochemical potential gradient of a coupling ion (H(+) or Na(+)) as their energy source, and are composed of stator and rotor proteins. Sodium-driven and proton-driven motors have the stator proteins PomA and PomB or MotA and MotB, respectively, which interact with each other in their transmembrane (TM) regions to form an ion channel. The single TM region of PomB or MotB, which forms the ion-conduction pathway together with TM3 and TM4 of PomA or MotA, respectively, has a highly conserved aspartate residue that is the ion binding site and is essential for rotation. To investigate the ion conductivity and selectivity of the Na(+)-driven PomA/PomB stator complex, we replaced conserved residues predicted to be near the conserved aspartate with H(+)-type residues, PomA-N194Y, PomB-F22Y and/or PomB-S27T. Motility analysis revealed that the ion specificity was not changed by either of the PomB mutations. PomB-F22Y required a higher concentration of Na(+) to exhibit swimming, but this effect was suppressed by additional mutations, PomA-N194Y or PomB-S27T. Moreover, the motility of the PomB-F22Y mutant was resistant to phenamil, a specific inhibitor for the Na(+) channel. When PomB-F22 was changed to other amino acids and the effects on swimming ability were investigated, replacement with a hydrophilic residue decreased the maximum swimming speed and conferred strong resistance to phenamil. From these results, we speculate that the Na(+) flux is reduced by the PomB-F22Y mutation, and that PomB-F22 is important for the effective release of Na(+) from PomB-D24.

Moteurs piézo-électriques à onde progressive : I. Modélisation de la conversion d'énergie mécanique à l'interface stator/rotor

NASA Astrophysics Data System (ADS)

Minotti, P.; Le Moal, P.; Buchaillot, L.; Ferreira, A.

1996-10-01

The modeling of traveling wave type piezoelectric motors involves a large variety of mechanical and physical phenomena and therefore leads to numerous approaches and models. The latter, mainly based on phenomenological and numerical (based on Finite Element Method) analyses, are not suitable for current objectives oriented toward the development of efficient C.A.D. tools. As a result, an attempt is done to investigate analytical approaches, in order to theoretically model the mechanical energy conversion at the stator/rotor interface. This paper is the first in a serie of three articles devoted to the modeling of such rotative motors. After a short description of the operating principles specific to the piezomotors, the mechanical and tribological assumptions made for the driving mechanism of the rotor are briefly described. Then it is shown that the kinematic and dynamic modeling of the stator, combined with the static representation of the stator/rotor interface, gives an efficient way in order to perform the calculation of the loading characteristics of the driving shaft. Finally, the specifications of a new software named C.A.S.I.M.M.I.R.E., which has been recently developed on the basis of our earlier mechanical modeling, are described. In the last of these three papers, the theoretical simulations performed on SHINSEI Japanese motors will show to be close to the experimental data and that the results reported in this paper will lead to the structural optimization of future traveling wave ultrasonic motors. La modélisation des moteurs piézo-électriques à onde progressive implique une grande variété de phénomènes physiques et mécaniques. Cette variété conduit à des approches et modèles tout aussi nombreux et variés, qui reposent principalement sur des analyses phénoménologiques et numériques (Méthode Élements Finis), et ne permettent pas de répondre aux éxigences actuelles concernant le développement d'outils C.A.O. performants. Cette n

Transient technique for measuring heat transfer coefficients on stator airfoils in a jet engine environment

NASA Astrophysics Data System (ADS)

Gladden, H. J.; Proctor, M. P.

A transient technique was used to measure heat transfer coefficients on stator airfoils in a high-temperature annular cascade at real engine conditions. The transient response of thin film thermocouples on the airfoil surface to step changes in the gas stream temperature was used to determine these coefficients. In addition, gardon gages and paired thermocouples were also utilized to measure heat flux on the airfoil pressure surface at steady state conditions. The tests were conducted at exit gas stream Reynolds numbers of one-half to 1.9 million based on true chord. The results from the transient technique show good comparison with the steady-state results in both trend and magnitude. In addition, comparison is made with the STAN5 boundary layer code and shows good comparison with the trends. However, the magnitude of the experimental data is consistently higher than the analysis.

Transient technique for measuring heat transfer coefficients on stator airfoils in a jet engine environment

NASA Technical Reports Server (NTRS)

Gladden, H. J.; Proctor, M. P.

1985-01-01

A transient technique was used to measure heat transfer coefficients on stator airfoils in a high-temperature annular cascade at real engine conditions. The transient response of thin film thermocouples on the airfoil surface to step changes in the gas stream temperature was used to determine these coefficients. In addition, gardon gages and paired thermocouples were also utilized to measure heat flux on the airfoil pressure surface at steady state conditions. The tests were conducted at exit gas stream Reynolds numbers of one-half to 1.9 million based on true chord. The results from the transient technique show good comparison with the steady-state results in both trend and magnitude. In addition, comparison is made with the STAN5 boundary layer code and shows good comparison with the trends. However, the magnitude of the experimental data is consistently higher than the analysis.

Aerodynamic Design of a Four-Stage Low-Speed Axial Compressor for Cantilevered Stator Research

NASA Astrophysics Data System (ADS)

Wallace, James N.

This research is focused on the baseline aerodynamic design of a four-stage low-speed axial compressor with the intent to achieve similarity of cantilevered stator hub leakage flows with those in the rear stages of Siemens large gas turbine compressors. The baseline airfoil design is to act as a comparison for all future research completed in the low speed compressor and, therefore, will not include possible future research topics such as 3-D airfoil geometry or end-wall contouring. Following the design of the airfoils is the aerodynamic design of the facility including the inlet and exhaust. These components were designed to eliminate interactions of the compressor with the facility and to accommodate instrumentation. A baseline set of aerodynamic instrumentation is then suggested to characterize compressor performance. Fully 3-D steady CFD was used extensively during the design of both the facility and the compressor, as well as determining the locations and types of instrumentation.

Unsteady Loss in the Stator Due to the Incoming Rotor Wake in a Highly-Loaded Transonic Compressor

NASA Technical Reports Server (NTRS)

Hah, Chunill

2015-01-01

The present paper reports an investigation of unsteady loss generation in the stator due to the incoming rotor wake in an advanced GE transonic compressor design with a high-fidelity numerical method. This advanced compressor with high reaction and high stage loading has been investigated both experimentally and analytically in the past. The measured efficiency in this advanced compressor is significantly lower than the design intention goal. The general understanding is that the current generation of compressor design analysis tools miss some important flow physics in this modern compressor design. To pinpoint the source of the efficiency miss, an advanced test with a detailed flow traverse was performed for the front one and a half stage at the NASA Glenn Research Center.

Streakline flow visualization study of a horseshoe vortex in a large-scale, two-dimensional turbine stator cascade

NASA Technical Reports Server (NTRS)

Gaugler, R. E.; Russell, L. M.

1980-01-01

Neutrally buoyant helium-filled bubbles were observed as they followed the streamlines in a horseshoe vortex system around the vane leading edge in a large-scale, two-dimensional, turbine stator cascade. Bubbles were introduced into the endwall boundary layer through a slot upstream of the vane leading edge. The paths of the bubbles were recorded photographically as streaklines on 16-mm movie film. Individual frames from the film have been selected, and overlayed to show the details of the horseshoe vortex around the leading edge. The transport of the vortex across the passage near the leading edge is clearly seen when compared to the streaks formed by bubbles carried in the main stream. Limiting streamlines on the endwall surface were traced by the flow of oil drops.

Theory for broadband Noise of Rotor and Stator Cascades with Inhomogeneous Inflow Turbulence Including Effects of Lean and Sweep

NASA Technical Reports Server (NTRS)

Hanson, Donald B.

2001-01-01

The problem of broadband noise generated by turbulence impinging on a downstream blade row is examined from a theoretical viewpoint. Equations are derived for sound power spectra in terms of 3 dimensional wavenumber spectra of the turbulence. Particular attention is given to issues of turbulence inhomogeneity associated with the near field of the rotor and variations through boundary layers. Lean and sweep of the rotor or stator cascade are also handled rigorously with a full derivation of the relevant geometry and definitions of lean and sweep angles. Use of the general theory is illustrated by 2 simple theoretical spectra for homogeneous turbulence. Limited comparisons are made with data from model fans designed by Pratt & Whitney, Allison, and Boeing. Parametric studies for stator noise are presented showing trends with Mach number, vane count, turbulence scale and intensity, lean, and sweep. Two conventions are presented to define lean and sweep. In the "cascade system" lean is a rotation out of its plane and sweep is a rotation of the airfoil in its plane. In the "duct system" lean is the leading edge angle viewing the fan from the front (along the fan axis) and sweep is the angle viewing the fan from the side (,perpendicular to the axis). It is shown that the governing parameter is sweep in the plane of the airfoil (which reduces the chordwise component of Mach number). Lean (out of the plane of the airfoil) has little effect. Rotor noise predictions are compared with duct turbulence/rotor interaction noise data from Boeing and variations, including blade tip sweep and turbulence axial and transverse scales are explored.

Single-stage experimental evaluation of tandem-airfoil rotor and stator blading for compressors. Part 2: Data and performance for stage A

NASA Technical Reports Server (NTRS)

Brent, J. A.

1972-01-01

Stage A, comprised of a conventional rotor and stator, was designed and tested to establish a performance baseline for comparison with the results of subsequent tests planned for two tandem-blade stages. The rotor had an inlet hub/tip ratio of 0.8 and a design tip velocity of 757 ft/sec. At design equivalent rotor speed, rotor A achieved a maximum adiabatic efficiency of 85.1 percent at a pressure ratio of 1.29. The stage maximum adiabatic efficiency was 78.6 percent at a pressure ratio of 1.27.

Loss measurement and analysis for the prototype generator with HTS stator and permanent magnet rotor

NASA Astrophysics Data System (ADS)

Song, Peng; Qu, Timing; Yu, Xiaoyu; Li, Longnian; Gu, Chen; Li, Xiaohang; Wang, Dewen; Hu, Boping; Chen, Duxing; Han, Zhenghe

2013-11-01

A prototype HTS synchronous generator with a permanent magnet rotor and HTS armature windings was developed. The rated armature frequency is 10 Hz. The cryogenic Dewar is tightly surrounded outside the iron core. Both HTS coils and the iron core were cooled by using conduction cooling method. During the process of no-load running, the no-load loss power data were obtained through the torque measurement. The temperature evolution characteristics of the stator was measured by PT-100 temperature sensors. These results show that the no-load loss power at around 77 K are much larger than that at room temperature. The possible reason for the no-load loss increment is discussed. The ac loss power of one individual HTS coil used in this generator was also tested. Compared with the iron loss power, the ac loss power is rather small and could be neglected.

Cold-air performance of free-power turbine designed for 112-kilowatt automotive gas-turbine engine. 1: Design Stator-vane-chord setting angle of 35 deg

NASA Technical Reports Server (NTRS)

Kofskey, M. G.; Nusbaum, W. J.

1978-01-01

A cold air experimental investigation of a free power turbine designed for a 112-kW automotive gas-turbine was made over a range of speeds from 0 to 130 percent of design equivalent speeds and over a range of pressure ratio from 1.11 to 2.45. Results are presented in terms of equivalent power, torque, mass flow, and efficiency for the design power point setting of the variable stator.

Design and two dimensional cascade test of a jet-flap turbine stator blade with ratio of axial chord to spacing of 0.5

NASA Technical Reports Server (NTRS)

Stabe, R. G.

1971-01-01

A jet-flap blade was designed for a velocity diagram typical of the first-stage stator of a jet engine turbine and was tested in a simple two-dimensional cascade of six blades. The principal measurements were blade surface static pressure and cross-channel surveys of exit total pressure, static pressure, and flow angle. The results of the experimental investigation include blade loading, exit angle, flow, and loss data for a range of exit critical velocity ratios and three jet flow conditions.

Peripheral stator of the yeast V-ATPase: stoichiometry and specificity of interaction between the EG complex and subunits C and H.

PubMed

Féthière, James; Venzke, David; Madden, Dean R; Böttcher, Bettina

2005-12-06

V-ATPases are multisubunit membrane protein complexes that use the energy provided by ATP hydrolysis to generate a proton gradient across various intracellular and plasma membranes. In doing so, they maintain an acidic pH in the lumen of intracellular organelles and acidify extracellular milieu to support specific cellular functions. V-ATPases are structurally similar to the F1F0-ATP synthase, with an intrinsic membrane domain (V0) and an extrinsic peripheral domain (V1) joined by several connecting elements. To gain a clear functional understanding of the catalytic mechanism, and of the stability requirements for regulatory processes in the enzyme, a clear topology of the enzyme has to be established. In particular, the composition and arrangement of the peripheral stator subunits must be firmly settled, as these play specific roles in catalysis and regulation. We have designed a strategy allowing us to coexpress different combinations of these subunits to delineate specific interactions. In this study, we report the interaction between the peripheral stator EG complex and subunits C and H of the V-ATPase from the yeast Saccharomyces cerevisae. A combination of analytical gel filtration, native gel electrophoresis, and ultracentrifugation analysis allowed us to ascertain the homogeneity and molar mass of the purified EGC complex as well as of the EG complex, supporting the formation of 1:1(:1) stoichiometric complexes. The EGC complex can be formed in vitro by combining equimolar amounts of subunit C and the EG subcomplex and results most likely from the initial interaction between subunits E and C.

Analysis on accuracy improvement of rotor-stator rubbing localization based on acoustic emission beamforming method.

PubMed

He, Tian; Xiao, Denghong; Pan, Qiang; Liu, Xiandong; Shan, Yingchun

2014-01-01

This paper attempts to introduce an improved acoustic emission (AE) beamforming method to localize rotor-stator rubbing fault in rotating machinery. To investigate the propagation characteristics of acoustic emission signals in casing shell plate of rotating machinery, the plate wave theory is used in a thin plate. A simulation is conducted and its result shows the localization accuracy of beamforming depends on multi-mode, dispersion, velocity and array dimension. In order to reduce the effect of propagation characteristics on the source localization, an AE signal pre-process method is introduced by combining plate wave theory and wavelet packet transform. And the revised localization velocity to reduce effect of array size is presented. The accuracy of rubbing localization based on beamforming and the improved method of present paper are compared by the rubbing test carried on a test table of rotating machinery. The results indicate that the improved method can localize rub fault effectively. Copyright © 2013 Elsevier B.V. All rights reserved.

Magnetic Flux Compression Using Detonation Plasma Armatures and Superconductor Stators: Integrated Propulsion and Power Applications

NASA Technical Reports Server (NTRS)

Litchford, Ron; Robertson, Tony; Hawk, Clark; Turner, Matt; Koelfgen, Syri

1999-01-01

This presentation discusses the use of magnetic flux compression for space flight applications as a propulsion and other power applications. The qualities of this technology that make it suitable for spaceflight propulsion and power, are that it has high power density, it can give multimegawatt energy bursts, and terawatt power bursts, it can produce the pulse power for low impedance dense plasma devices (e.g., pulse fusion drivers), and it can produce direct thrust. The issues of a metal vs plasma armature are discussed, and the requirements for high energy output, and fast pulse rise time requires a high speed armature. The plasma armature enables repetitive firing capabilities. The issues concerning the high temperature superconductor stator are also discussed. The concept of the radial mode pulse power generator is described. The proposed research strategy combines the use of computational modeling (i.e., magnetohydrodynamic computations, and finite element modeling) and laboratory experiments to create a demonstration device.

Treatment of wastewater containing o-phenylenediamine by ozone in a rotor-stator reactor.

PubMed

Arowo, Moses; Li, Yingwen; Chu, Guangwen; Sun, Baochang; Chen, Jianfeng; Shao, Lei

2016-01-01

This work employed a novel rotor-stator reactor (RSR) to intensify the degradation process of o-phenylenediamine (o-PDA) by ozone. The effects of different operating parameters including initial pH, temperature, rotation speed, liquid volumetric flow rate and inlet ozone concentration on the removal efficiency of o-PDA were investigated in an attempt to establish the optimum conditions. The removal efficiency was evaluated in terms of degradation ratio and chemical oxygen demand (COD) reduction ratio of the o-PDA wastewater. Results indicate that the removal efficiency decreased with increasing liquid volumetric flow rate but increased with an increase in pH and inlet ozone concentration. Also, the removal efficiency increased up to a certain level with an increase in rotation speed and temperature. Additionally, a comparison experiment was carried out in a stirred tank reactor (STR), and the results show that the degradation and COD reduction ratios reached a maximum of 94.6% and 61.2% in the RSR as compared to 45.3% and 28.6% in the STR, respectively. This work demonstrates that ozone oxidation carried out in RSR may be a promising alternative for pre-treatment of o-PDA wastewater.

Detection of stator winding faults in induction motors using three-phase current monitoring.

PubMed

Sharifi, Rasool; Ebrahimi, Mohammad

2011-01-01

The objective of this paper is to propose a new method for the detection of inter-turn short circuits in the stator windings of induction motors. In the previous reported methods, the supply voltage unbalance was the major difficulty, and this was solved mostly based on the sequence component impedance or current which are difficult to implement. Some other methods essentially are included in the offline methods. The proposed method is based on the motor current signature analysis and utilizes three phase current spectra to overcome the mentioned problem. Simulation results indicate that under healthy conditions, the rotor slot harmonics have the same magnitude in three phase currents, while under even 1 turn (0.3%) short circuit condition they differ from each other. Although the magnitude of these harmonics depends on the level of unbalanced voltage, they have the same magnitude in three phases in these conditions. Experiments performed under various load, fault, and supply voltage conditions validate the simulation results and demonstrate the effectiveness of the proposed technique. It is shown that the detection of resistive slight short circuits, without sensitivity to supply voltage unbalance is possible. Copyright © 2010 ISA. Published by Elsevier Ltd. All rights reserved.

Low-Noise Potential of Advanced Fan Stage Stator Vane Designs Verified in NASA Lewis Wind Tunnel Test

NASA Technical Reports Server (NTRS)

Hughes, Christopher E.

1999-01-01

With the advent of new, more stringent noise regulations in the next century, aircraft engine manufacturers are investigating new technologies to make the current generation of aircraft engines as well as the next generation of advanced engines quieter without sacrificing operating performance. A current NASA initiative called the Advanced Subsonic Technology (AST) Program has set as a goal a 6-EPNdB (effective perceived noise) reduction in aircraft engine noise relative to 1992 technology levels by the year 2000. As part of this noise program, and in cooperation with the Allison Engine Company, an advanced, low-noise, high-bypass-ratio fan stage design and several advanced technology stator vane designs were recently tested in NASA Lewis Research Center's 9- by 15-Foot Low-Speed Wind Tunnel (an anechoic facility). The project was called the NASA/Allison Low Noise Fan.

Streakline flow visualization study of a horseshoe vortex in a large-scale, two-dimensional turbine stator cascade

NASA Technical Reports Server (NTRS)

Gaugler, R. E.; Russell, L. M.

1979-01-01

Neutrally bouyant helium-filled bubbles were observed as they followed the streamlines in a horseshoe vortex system around the vane leading edge in a large scale, two dimensional, turbine stator cascade. Inlet Reynolds number, based on true chord, ranged between 100,000 to 300,000. Bubbles were introduced into the endwall boundary layer through a slot upstream of the vane leading edge. The paths of the bubbles were recorded photographically as streaklines on 16 mm movie film. Individual frames from the film were selected, and overlayed to show the details of the horseshoe vortex around the leading edge. The transport of the vortex across the passage near the leading edge is clearly seen when compared to the streaks formed by bubbles carried in the main stream. Limiting streamlines on the endwall surface were traced by the flow of oil drops.

Root Cause Failure Analysis of Stator Winding Insulation failure on 6.2 MW hydropower generator

NASA Astrophysics Data System (ADS)

Adhi Nugroho, Agus; Widihastuti, Ida; Ary, As

2017-04-01

Insulation failure on generator winding insulation occurred in the Wonogiri Hydropower plant has caused stator damage since ase was short circuited to ground. The fault has made the generator stop to operate. Wonogiri Hydropower plant is one of the hydroelectric plants run by PT. Indonesia Power UBP Mrica with capacity 2 × 6.2 MW. To prevent damage to occur again on hydropower generators, an analysis is carried out using Root Cause Failure Analysis RCFA is a systematic approach to identify the root cause of the main orbasic root cause of a problem or a condition that is not wanted. There are several aspects to concerned such as: loading pattern and operations, protection systems, generator insulation resistance, vibration, the cleanliness of the air and the ambient air. Insulation damage caused by gradual inhomogeneous cooling at the surface of winding may lead in to partial discharge. In homogeneous cooling may present due to lattice hampered by dust and oil deposits. To avoid repetitive defects and unwanted condition above, it is necessary to perform major maintenance overhaul every 5000-6000 hours of operation.

Surface temperature measurements from a stator vane doublet in a turbine afterburner flame using a YAG:Tm thermographic phosphor

NASA Astrophysics Data System (ADS)

Eldridge, Jeffrey I.; Allison, Stephen W.; Jenkins, Thomas P.; Gollub, Sarah L.; Hall, Carl A.; Walker, D. Greg

2016-12-01

Phosphor thermometry measurements in turbine engine environments can be difficult because of high background radiation levels. To address this challenge, luminescence lifetime-based phosphor thermometry measurements were obtained using thulium-doped Y3Al5O12 (YAG:Tm) to take advantage of the emission wavelengths at 365 nm (1D2  →  3H6 transition) and at 456 nm (1D2  →  3F4 transition). At these wavelengths, turbine engine radiation background is reduced compared with emission from longer wavelength phosphors. Temperature measurements of YAG:Tm coatings were demonstrated using decay of both the 365 and 456 nm emission bands in a furnace environment up to 1400 °C. To demonstrate that reliable surface temperatures based on short-wavelength YAG:Tm emission could be obtained from the surface of an actual engine component in a high gas velocity, highly radiative environment, measurements were obtained from a YAG:Tm-coated Honeywell stator vane doublet placed in the afterburner flame exhaust stream of the augmenter-equipped General Electric J85 turbojet test engine at the University of Tennessee Space Institute (UTSI). Using a probe designed for engine insertion, spot temperature measurements were obtained by measuring luminescence decay times over a range of steady state throttle settings as well as during an engine throttle acceleration. YAG:Tm phosphor thermometry measurements of the stator vane surface in the afterburner exhaust stream using the decay of the 456 nm emission band were successfully obtained at temperatures up to almost 1300 °C. Phosphor thermometry measurements acquired with the engine probe using the decay of the 365 nm emission band were not successful at usefully high temperatures because the probe design allowed transmission of intense unfiltered silica Raman scattering that produced photomultiplier tube saturation with extended recovery times. Recommendations are made for probe modifications that will enable

Windage Power Loss in Gas Foil Bearings and the Rotor-Stator Clearance of High Speed Generators Operating in High Pressure Environments

NASA Technical Reports Server (NTRS)

Bruckner, Robert J.

2009-01-01

Closed Brayton Cycle (CBC) and Closed Supercritical Cycle (CSC) engines are prime candidates to convert heat from a reactor into electric power for robotic space exploration and habitation. These engine concepts incorporate a permanent magnet starter/generator mounted on the engine shaft along with the requisite turbomachinery. Successful completion of the long-duration missions currently anticipated for these engines will require designs that adequately address all losses within the machine. The preliminary thermal management concept for these engine types is to use the cycle working fluid to provide the required cooling. In addition to providing cooling, the working fluid will also serve as the bearing lubricant. Additional requirements, due to the unique application of these microturbines, are zero contamination of the working fluid and entirely maintenance-free operation for many years. Losses in the gas foil bearings and within the rotor-stator gap of the generator become increasingly important as both rotational speed and mean operating pressure are increased. This paper presents the results of an experimental study, which obtained direct torque measurements on gas foil bearings and generator rotor-stator gaps. Test conditions for these measurements included rotational speeds up to 42,000 revolutions per minute, pressures up to 45 atmospheres, and test gases of nitrogen, helium, and carbon dioxide. These conditions provided a maximum test Taylor number of nearly one million. The results show an exponential rise in power loss as mean operating density is increased for both the gas foil bearing and generator windage. These typical "secondary" losses can become larger than the total system output power if conventional design paradigms are followed. A nondimensional analysis is presented to extend the experimental results into the CSC range for the generator windage.

MotPS is the stator-force generator for motility of alkaliphilic Bacillus, and its homologue is a second functional Mot in Bacillus subtilis.

PubMed

Ito, Masahiro; Hicks, David B; Henkin, Tina M; Guffanti, Arthur A; Powers, Benjamin D; Zvi, Lior; Uematsu, Katsuyuki; Krulwich, Terry A

2004-08-01

The stator-force generator that drives Na+-dependent motility in alkaliphilic Bacillus pseudofirmus OF4 is identified here as MotPS, MotAB-like proteins with genes that are downstream of the ccpA gene, which encodes a major regulator of carbon metabolism. B. pseudofirmus OF4 was only motile at pH values above 8. Disruption of motPS resulted in a non-motile phenotype, and motility was restored by transformation with a multicopy plasmid containing the motPS genes. Purified and reconstituted MotPS from B. pseudofirmus OF4 catalysed amiloride analogue-sensitive Na+ translocation. In contrast to B. pseudofirmus, Bacillus subtilis contains both MotAB and MotPS systems. The role of the motPS genes from B. subtilis in several motility-based behaviours was tested in isogenic strains with intact motAB and motPS loci, only one of the two mot systems or neither mot system. B. subtilis MotPS (BsMotPS) supported Na+-stimulated motility, chemotaxis on soft agar surfaces and biofilm formation, especially after selection of an up-motile variant. BsMotPS also supported motility in agar soft plugs immersed in liquid; motility was completely inhibited by an amiloride analogue. BsMotPS did not support surfactin-dependent swarming on higher concentration agar surfaces. These results indicate that BsMotPS contributes to biofilm formation and motility on soft agar, but not to swarming, in laboratory strains of B. subtilis in which MotAB is the dominant stator-force generator. BsMotPS could potentially be dominant for motility in B. subtilis variants that arise in particular niches.

Single-stage experimental evaluation of tandem-airfoil rotor and stator blading for compressors. Part 5: Analysis and design of stages D and E

NASA Technical Reports Server (NTRS)

Brent, J. A.; Cheatham, J. G.; Clemmons, D. R.

1972-01-01

A conventional and a tandem bladed stage were designed for a comparative experimental evaluation in a 0.8 hub/tip ratio single-stage compressor. Based on a preliminary design study, a radially constant work input distribution was selected for the rotor designs. Velocity diagrams and blade leading and trailing edge angles selected for the conventional rotor and stator were used in the design of the tandem blading. The effects of axial velocity ratio and secondary flow on turning were included in the selection of blade leading and trailing edge angles. Design values of rotor tip velocity and stage pressure ratio were 757 ft/sec and 1.26, respectively.

Inbreeding depression in two seed-feeding beetles, Callosobruchus maculatus and Stator limbatus (Coleoptera: Chrysomelidae).

PubMed

Fox, C W; Scheibly, K L; Smith, B P; Wallin, W G

2007-02-01

Inbreeding depression is well documented in insects but the degree to which inbreeding depression varies among populations within species, and among traits within populations, is poorly studied in insects other than Drosophila. Inbreeding depression was examined in two long-term laboratory colonies of the seed beetle, Callosobruchus maculatus (Fabricius), which are used frequently as models for experiments in ecology, evolution and behaviour. Inbreeding depression in these laboratory colonies are compared with one recently field-collected population of a different seed beetle, Stator limbatus Horn. Inbreeding reduced embryogenesis, egg hatch and larval survival in both species, such that eggs produced by sib matings were >17% less likely to produce an adult offspring. Inbred larvae also took 4-6% longer to develop to emergence in both species. Inbreeding depression varied among the measured traits but did not differ between the two populations of C. maculatus for any trait, despite the large geographic distance between source populations (western Africa vs. southern India). Inbreeding depression was similar in magnitude between C. maculatus and S. limbatus. This study demonstrates that these laboratory populations of C. maculatus harbour substantial genetic loads, similar to the genetic load of populations of S. limbatus recently collected from the field.

The effects of inlet turbulence and rotor/stator interactions on the aerodynamics and heat transfer of a large-scale rotating turbine model. Volume 2: Heat transfer data tabulation. 15 percent axial spacing

NASA Technical Reports Server (NTRS)

Dring, R. P.; Blair, M. F.; Joslyn, H. D.

1986-01-01

A combined experimental and analytical program was conducted to examine the effects of inlet turbulence on airfoil heat transfer. The experimental portion of the study was conducted in a large-scale (approx 5X engine), ambient temperature, rotating turbine model configured in both single stage and stage-and-a-half arrangements. Heat transfer measurements were obtained using low-conductivity airfoils with miniature thermcouples welded to a thin, electrically heated surface skin. Heat transfer data were acquired for various combinations of low or high inlet turbulence intensity, flow coefficient, first-stator/rotor axial spacing, Reynolds number and relative circumferential position of the first and second stators. Aerodynamic measurements obtained as part of the program include distributions of the mean and fluctuating velocities at the turbine inlet and, for each airfoil row, midspan airfoil surface pressures and circumferential distributions of the downstream steady state pressures and fluctuating velocities. Analytical results include airfoil heat transfer predictions produced using existing 2-D boundary layer computation schemes and an examination of solutions of the unsteady boundary layer equations. The results are reported in four separate volumes, of which this is Volume 2: Heat Transfer Data Tabulation; 15 Percent Axial Spacing.

Component Performance Investigation of J71 Experimental Turbine I : Over-all Performance with 97-percent-design Stator Areas

NASA Technical Reports Server (NTRS)

Schum, Harold J; Davison, Elmer H

1956-01-01

The over-all component performance characteristics of a J71 experimental three-stage turbine with 97 percent design stator areas were determined over a range of speed and pressure ratio at inlet-air conditions of approximately 35 inches of mercury absolute and 700 degrees R. The turbine break internal efficiency at design operating conditions was 0.877; the maximum efficiency of 0.886 occurred at a pressure ratio of 4.0 at 120 percent of design equivalent rotor speed. In general, the turbine yielded a wide range of efficient operation, permitting flexibility in the choice of different modes of engine operation. Limiting blade loading of the third rotor was approached but not obtained over the range of conditions investigated herein. At the design operating point, the turbine equivalent weight flow was approximately 105 percent of design. Choking of the third-rotor blades occurred at design speed and an over-all pressure ratio of 4.2.

Biodiesel production process intensification using a rotor-stator type generator of hydrodynamic cavitation.

PubMed

Crudo, Daniele; Bosco, Valentina; Cavaglià, Giuliano; Grillo, Giorgio; Mantegna, Stefano; Cravotto, Giancarlo

2016-11-01

Triglyceride transesterification for biodiesel production is a model reaction which is used to compare the conversion efficiency, yield, reaction time, energy consumption, scalability and cost estimation of different reactor technology and energy source. This work describes an efficient, fast and cost-effective procedure for biodiesel preparation using a rotating generator of hydrodynamic cavitation (HC). The base-catalyzed transesterification (methanol/sodium hydroxide) has been carried out using refined and bleached palm oil and waste vegetable cooking oil. The novel HC unit is a continuous rotor-stator type reactor in which reagents are directly fed into the controlled cavitation chamber. The high-speed rotation of the reactor creates micron-sized droplets of the immiscible reacting mixture leading to outstanding mass and heat transfer and enhancing the kinetics of the transesterification reaction which completes much more quickly than traditional methods. All the biodiesel samples obtained respect the ASTM standard and present fatty acid methyl ester contents of >99% m/m in both feedstocks. The electrical energy consumption of the HC reactor is 0.030kWh per L of produced crude biodiesel, making this innovative technology really quite competitive. The reactor can be easily scaled-up, from producing a few hundred to thousands of liters of biodiesel per hour while avoiding the risk of orifices clogging with oil impurities, which may occur in conventional HC reactors. Furthermore it requires minimal installation space due to its compact design, which enhances overall security. Copyright © 2016 Elsevier B.V. All rights reserved.

Active Control of Low-Speed Fan Tonal Noise Using Actuators Mounted in Stator Vanes: Part III Results

NASA Technical Reports Server (NTRS)

Sutliff, Daniel L.; Remington, Paul J.; Walker, Bruce E.

2003-01-01

A test program to demonstrate simplification of Active Noise Control (ANC) systems relative to standard techniques was performed on the NASA Glenn Active Noise Control Fan from May through September 2001. The target mode was the m = 2 circumferential mode generated by the rotor-stator interaction at 2BPF. Seven radials (combined inlet and exhaust) were present at this condition. Several different error-sensing strategies were implemented. Integration of the error-sensors with passive treatment was investigated. These were: (i) an in-duct linear axial array, (ii) an induct steering array, (iii) a pylon-mounted array, and (iv) a near-field boom array. The effect of incorporating passive treatment was investigated as well as reducing the actuator count. These simplified systems were compared to a fully ANC specified system. Modal data acquired using the Rotating Rake are presented for a range of corrected fan rpm. Simplified control has been demonstrated to be possible but requires a well-known and dominant mode signature. The documented results here in are part III of a three-part series of reports with the same base title. Part I and II document the control system and error-sensing design and implementation.

Experimental investigation of the microscale rotor-stator cavity flow with rotating superhydrophobic surface

NASA Astrophysics Data System (ADS)

Wang, Chunze; Tang, Fei; Li, Qi; Wang, Xiaohao

2018-03-01

The flow characteristics of microscale rotor-stator cavity flow and the drag reduction mechanism of the superhydrophobic surface with high shearing stress were investigated. A microscale rotating flow testing system was established based on micro particle image velocimetry (micro-PIV), and the flow distribution under different Reynolds numbers (7.02 × 103 ≤ Re ≤ 3.51 × 104) and cavity aspect ratios (0.013 ≤ G ≤ 0.04) was measured. Experiments show that, for circumferential velocity, the flow field distributes linearly in rotating Couette flow in the case of low Reynolds number along the z-axis, while the boundary layer separates and forms Batchelor flow as the Reynolds number increases. The separation of the boundary layer is accelerated with the increase of cavity aspect ratio. The radial velocities distribute in an S-shape along the z-axis. As the Reynolds number and cavity aspect ratio increase, the maximum value of radial velocity increases, but the extremum position at rotating boundary remains at Z* = 0.85 with no obvious change, while the extremum position at the stationary boundary changes along the z-axis. The model for the generation of flow disturbance and the transmission process from the stationary to the rotating boundary was given by perturbation analysis. Under the action of superhydrophobic surface, velocity slip occurs near the rotating boundary and the shearing stress reduces, which leads to a maximum drag reduction over 51.4%. The contours of vortex swirling strength suggest that the superhydrophobic surface can suppress the vortex swirling strength and repel the vortex structures, resulting in the decrease of shearing Reynolds stress and then drag reduction.

Evaluation of range and distortion tolerance for high Mach number transonic fan stages. Task 2: Performance of a 1500-foot-per-second tip speed transonic fan stage with variable geometry inlet guide vanes and stator

NASA Technical Reports Server (NTRS)

Bilwakesh, K. R.; Koch, C. C.; Prince, D. C.

1972-01-01

A 0.5 hub/tip radius ratio compressor stage consisting of a 1500 ft/sec tip speed rotor, a variable camber inlet guide vane and a variable stagger stator was designed and tested with undistorted inlet flow, flow with tip radial distortion, and flow with 90 degrees, one-per-rev, circumferential distortion. At the design speed and design IGV and stator setting the design stage pressure ratio was achieved at a weight within 1% of the design flow. Analytical results on rotor tip shock structure, deviation angle and part-span shroud losses at different operating conditions are presented. The variable geometry blading enabled efficient operation with adequate stall margin at the design condition and at 70% speed. Closing the inlet guide vanes to 40 degrees changed the speed-versus-weight flow relationship along the stall line and thus provided the flexibility of operation at off-design conditions. Inlet flow distortion caused considerable losses in peak efficiency, efficiency on a constant throttle line through design pressure ratio at design speed, stall pressure ratio, and stall margin at the 0 degrees IGV setting and high rotative speeds. The use of the 40 degrees inlet guide vane setting enabled partial recovery of the stall margin over the standard constant throttle line.

Development of the pump protection system against cavitation on the basis of the stator current signature analysis of drive electric motor

NASA Astrophysics Data System (ADS)

Kipervasser, M. V.; Gerasimuk, A. V.; Simakov, V. P.

2018-05-01

In the present paper a new registration method of such inadmissible phenomenon as cavitation in the operating mode of centrifugal pump is offered. Influence of cavitation and extent of its development on the value of mechanical power consumed by the pump from the electric motor is studied. On the basis of design formulas the joint mathematical model of centrifugal pumping unit with the synchronous motor is created. In the model the phenomena accompanying the work of a pumping installation in the cavitation mode are considered. Mathematical modeling of the pump operation in the considered emergency operation is carried out. The chart of stator current of the electric motor, depending on the degree of cavitation development of is received. On the basis of the analysis of the obtained data the conclusion on the possibility of registration of cavitation by the current of drive electric motor is made and the functional diagram of the developed protection system is offered, its operation principle is described.

PIV measurements of a jet impinging on an opened rotor-stator system at low gap spacing

NASA Astrophysics Data System (ADS)

Nguyen, Thien; Pellé}, Julien; Harmand, Souad

2011-11-01

The current work experimentally investigates the flow characteristics of an air jet impinging to an opened rotor-stator configuration at a low nondimensional spacing G = 0 . 02 and very low aspect ratio e / D = 0 . 25 . The rotational Reynolds numbers varied from 0 . 33 ×105 to 5 . 32 ×105 while the jet Reynolds numbers ranged from 17 . 2 ×103 to 43 ×103 . PIV measurements were performed at three axial planes for the entire disk diameter. The obtained PIV results agreed with those obtained by LDA measurements and numerical simulation reported in Poncet et al. 2005 (Physics of Fluids 17, 075110). A recirculation flow region, which centered at the impinging point and possessed high turbulent intensities, was observed. The mean flow and turbulent intensities were evaluated with the local heat transfer coefficients measured by Pellé and Harmand 2009 (Applied Thermal Engineering 29: 1532-1543). It is shown that the local peaks and the gradually rising of the radial heat transfer coefficients Nu are due to the secondary peaks and the increases near the outer radius of the turbulent intensity distributions respectively. POD analysis was applied to the cases of the impinging jet with and without rotation. It is shown that the first POD mode captured nearly 60 % total kinetic energy and the low-order POD modes revealed a spiral structure in the jet-dominated region.

DEL phenotype.

PubMed

Kwon, Dong H; Sandler, S G; Flegel, Willy A

2017-09-01

DEL red blood cells (RBCs) type as D- by routine serologic methods and are transfused routinely, without being identified as expressing a very weak D antigen, to D- recipients. DEL RBCs are detected only by adsorption and elution of anti-D or by molecular methods. Most DEL phenotypes have been reported in population studies conducted in East Asia, although DEL phenotypes have been detected also among Caucasian individuals. Approximately 98 percent of DEL phenotypes in East Asians are associated with the RHD*DEL1 or RHD*01EL.01 allele. The prevalence of DEL phenotypes has been reported among D- Han Chinese (30%), Japanese (28%), and Korean (17%) populations. The prevalence of DEL phenotypes is significantly lower among D- Caucasian populations (0.1%). Among the 3-5 percent of African individuals who are D-, there are no reports of the DEL phenotype. Case reports from East Asia indicate that transfusion of DEL RBCs to D- recipients has been associated with D alloimmunization. East Asian immigrants constitute 2.1 percent of the 318.9 million persons residing in the United States, and an estimated 2.8 percent are blood donors. Using these statistics, we estimate that 68-683 units of DEL RBCs from donors of East Asian ancestry are transfused as D- annually in the United States. Given the reports from East Asia of D alloimmunization attributed to transfusion of DEL RBCs, one would expect an occasional report of D alloimmunization in the United States following transfusion of DEL RBCs to a D- recipient. If such cases do occur, the most likely reason that they are not detected is the absence of active post-transfusion monitoring for formation of anti-D.

Analytical estimation on divergence and flutter vibrations of symmetrical three-phase induction stator via field-synchronous coordinates

NASA Astrophysics Data System (ADS)

Xia, Ying; Wang, Shiyu; Sun, Wenjia; Xiu, Jie

2017-01-01

The electromagnetically induced parametric vibration of the symmetrical three-phase induction stator is examined. While it can be analyzed by an approximate analytical or numerical method, more accurate and simple analytical method is desirable. This work proposes a new method based on the field-synchronous coordinates. A mechanical-electromagnetic coupling model is developed under this frame such that a time-invariant governing equation with gyroscopic term can be developed. With the general vibration theory, the eigenvalue is formulated; the transition curves between the stable and unstable regions, and response are all determined as closed-form expressions of basic mechanical-electromagnetic parameters. The dependence of these parameters on the instability behaviors is demonstrated. The results imply that the divergence and flutter instabilities can occur even for symmetrical motors with balanced, constant amplitude and sinusoidal voltage. To verify the analytical predictions, this work also builds up a time-variant model of the same system under the conventional inertial frame. The Floquét theory is employed to predict the parametric instability and the numerical integration is used to obtain the parametric response. The parametric instability and response are both well compared against those under the field-synchronous coordinates. The proposed field-synchronous coordinates allows a quick estimation on the electromagnetically induced vibration. The convenience offered by the body-fixed coordinates is discussed across various fields.

Experimental and numerical simulation of a rotor/stator interaction event localized on a single blade within an industrial high-pressure compressor

NASA Astrophysics Data System (ADS)

Batailly, Alain; Agrapart, Quentin; Millecamps, Antoine; Brunel, Jean-François

2016-08-01

This contribution addresses a confrontation between the experimental simulation of a rotor/stator interaction case initiated by structural contacts with numerical predictions made with an in-house numerical strategy. Contrary to previous studies carried out within the low-pressure compressor of an aircraft engine, this interaction is found to be non-divergent: high amplitudes of vibration are experimentally observed and numerically predicted over a short period of time. An in-depth analysis of experimental data first allows for a precise characterization of the interaction as a rubbing event involving the first torsional mode of a single blade. Numerical results are in good agreement with experimental observations: the critical angular speed, the wear patterns on the casing as well as the blade dynamics are accurately predicted. Through out the article, the in-house numerical strategy is also confronted to another numerical strategy that may be found in the literature for the simulation of rubbing events: key differences are underlined with respect to the prediction of non-linear interaction phenomena.

Assembly of the stator in Escherichia coli ATP synthase. Complexation of alpha subunit with other F1 subunits is prerequisite for delta subunit binding to the N-terminal region of alpha

PubMed Central

Senior, Alan E.; Muharemagi, Alma; Wilke-Mounts, Susan

2008-01-01

Alpha subunit of Escherichia coli ATP synthase was expressed with a C-terminal 6-His tag and purified. Pure alpha was monomeric, competent in nucleotide binding, and had normal N-terminal sequence. In F1-subunit dissociation/reassociation experiments it supported full reconstitution of ATPase, and reassociated complexes were able to bind to F1-depleted membranes with restoration of ATP-driven proton pumping. Therefore interaction between the stator delta subunit and the N-terminal residue 1-22 region of alpha occurred normally when pure alpha was complexed with other F1 subunits. On the other hand, three different types of experiment showed that no interaction occurred between pure delta and isolated alpha subunit. Unlike in F1, the N-terminal region of isolated alpha was not susceptible to trypsin cleavage. Therefore, during assembly of ATP synthase, complexation of alpha subunit with other F1 subunits is prerequisite for delta subunit binding to the N-terminal region of alpha. We suggest that the N-terminal 1-22 residues of alpha are sequestered in isolated alpha until released by binding of beta to alpha subunit. This prevents 1/1 delta/alpha complexes from forming, and provides a satisfactory explanation of the stoichiometry of one delta per three alpha seen in the F1 sector of ATP synthase, assuming that steric hindrance prevents binding of more than one delta to the alpha3/beta3 hexagon. The cytoplasmic fragment of the b subunit (bsol) did not bind to isolated alpha. It might also be that complexation of alpha with beta subunits is prerequisite for direct binding of stator b subunit to the F1-sector. PMID:17176112

Effect of Rotor- and Stator-Blade Modifications on Surge Performance of an 11-Stage Axial-Flow Compressor. I - Original Production Compressor of XJ40-WE-6 Engine

NASA Technical Reports Server (NTRS)

Finger, Harold B.; Essig, Robert H.; Conrad, E. William

1952-01-01

An investigation to increase the compressor surge-limit pressure ratio of the XJ40-WE-6 turbojet engine at high equivalent speeds was conducted at the NACA Lewis altitude wind tunnel. This report evaluates the compressor modifications which were restricted to (1) twisting rotor blades (in place) to change blade section angles and (2) inserting new stator diaphragms with different blade angles. Such configuration changes could be incorporated quickly and easily in existing engines at overhaul depots. It was found that slight improvements in the compressor surge limit were possible by compressor blade adjustment. However, some of the modifications also reduced the engine air flow and hence penalized the thrust. The use of a mixer assembly at the compressor outlet improved the surge limit with no appreciable thrust penalty.

Investigation of the unsteady pressure distribution on the blades of an axial flow fan

NASA Technical Reports Server (NTRS)

Henderson, R. E.; Franke, G. F.

1978-01-01

The unsteady response of a stator blade caused by the interaction of the stator with the wakes of an upstream rotor was investigated. Unsteady pressure distributions were measured using a blade instrumented with a series miniature pressure transducers. The influence of several geometrical and flow parameters - rotor/stator spacing, stator solidity and stator incidence angle - were studied to determine the unsteady response of the stator to these parameters. A major influence on the stator unsteady response is due to the stator solidity. At high solidities the blade-to-blade interference has a larger contribution. While the range of rotor/stator spacings investigated had a minor influence, the effect of stator incidence angle is significant. The data indicate the existence of an optimum positive incidence which minimizes the unsteady response.

Methods and apparatus for cooling wind turbine generators

DOEpatents

Salamah, Samir A [Niskayuna, NY; Gadre, Aniruddha Dattatraya [Rexford, NY; Garg, Jivtesh [Schenectady, NY; Bagepalli, Bharat Sampathkumaran [Niskayuna, NY; Jansen, Patrick Lee [Alplaus, NY; Carl, Jr., Ralph James

2008-10-28

A wind turbine generator includes a stator having a core and a plurality of stator windings circumferentially spaced about a generator longitudinal axis. A rotor is rotatable about the generator longitudinal axis, and the rotor includes a plurality of magnetic elements coupled to the rotor and cooperating with the stator windings. The magnetic elements are configured to generate a magnetic field and the stator windings are configured to interact with the magnetic field to generate a voltage in the stator windings. A heat pipe assembly thermally engaging one of the stator and the rotor to dissipate heat generated in the stator or rotor.

Flux control and one-hundred and eighty degree core systems

DOEpatents

Hsu, John S

2012-11-27

A two-phase or four-phase electric machine includes a first stator part and a second stator part disposed about ninety electrical degrees apart. Stator pole parts are positioned near the first stator part and the second stator part. An injector injects a third-harmonic frequency current that is separate from and not produced by the fundamental current driving the first stator part and the second stator part. The electric angular speed of the third-harmonic rotating field comprises .theta. ##EQU00001## where p comprises the number of pole pairs, .theta. comprises a mechanical angle and t comprise time in seconds.

Acerca del moho

EPA Pesticide Factsheets

El moho forma parte del medio ambiente natural. Afuera del hogar, el moho juega un papel en la naturaleza al desintegrar materias organicas tales como las hojas que se han caido o los arboles muertos. El moho puede crecer adentro del hogar cuando las espor

Produccion Gaseosa del Cometa Halley: Erupciones Y Fotodisociacion del Radical OH

NASA Astrophysics Data System (ADS)

Silva, A. M.; Mirabel, I. F.

1990-11-01

RESUMEN:En este trabajo informamos la detecci6n de 20 erupciones en la li'nea de =18cm (1667MHz) del radical OH en el Cometa Halley.Las observaciones incluyen todos los monitoreos existentes y se extienden desde 120 dias antes del perihelio hasta 90 dias despues.Se detectan bruscos crecimientos en el flujo medido,hasta un factor 1O,seguidos por decaimientos lentos asociados con la fotodisociaci6n del OH. Se obtuvieron valores para el tiempo de vida fotoquimico del OH y del H2O basandose en el modelo desarrollado previamente por Silva(1988). Esos tiempos de vida estan de acuerdo con predicciones teoricas y con las observaciones en el Ultravioleta, y los resultados, los que son fuertemente dependientes de la velocidad heliocentrica del Coineta (variando hasta un factor 6), han sido calculados para varios rangos de velocidad entre +28 y -28 km/seg. Key wo'L :

Motor for High Temperature Applications

NASA Technical Reports Server (NTRS)

Roopnarine (Inventor)

2013-01-01

A high temperature motor has a stator with poles formed by wire windings, and a rotor with magnetic poles on a rotor shaft positioned coaxially within the stator. The stator and rotor are built up from stacks of magnetic-alloy laminations. The stator windings are made of high temperature magnet wire insulated with a vitreous enamel film, and the wire windings are bonded together with ceramic binder. A thin-walled cylinder is positioned coaxially between the rotor and the stator to prevent debris from the stator windings from reaching the rotor. The stator windings are wound on wire spools made of ceramic, thereby avoiding need for mica insulation and epoxy/adhesive. The stator and rotor are encased in a stator housing with rear and front end caps, and rear and front bearings for the rotor shaft are mounted on external sides of the end caps to keep debris from the motor migrating into the bearings' races.

Rippled disc electrostatic generator/motor configurations utilizing magnetic insulation

DOEpatents

Post, Richard F

2017-04-04

Electrostatic generators/motors designs are provided that generally may include a first rippled stator centered about a longitudinal axis; a second rippled stator centered about the axis, a first rippled rotor centered about the axis and located between the first rippled stator and the second rippled stator. A magnetic field having field lines about parallel with the average plane of at least one of the first rippled stator or the second rippled stator is provided with either a Halbach array configuration or a conductor array configuration.

System and method to determine electric motor efficiency nonintrusively

DOEpatents

Lu, Bin [Kenosha, WI; Habetler, Thomas G [Snellville, GA; Harley, Ronald G [Lawrenceville, GA

2011-08-30

A system and method for nonintrusively determining electric motor efficiency includes a processor programed to, while the motor is in operation, determine a plurality of stator input currents, electrical input data, a rotor speed, a value of stator resistance, and an efficiency of the motor based on the determined rotor speed, the value of stator resistance, the plurality of stator input currents, and the electrical input data. The determination of the rotor speed is based on one of the input power and the plurality of stator input currents. The determination of the value of the stator resistance is based on at least one of a horsepower rating and a combination of the plurality of stator input currents and the electrical input data. The electrical input data includes at least one of an input power and a plurality of stator input voltages.

MEMS Micro-Translation Device with Improved Linear Travel Capability

NASA Technical Reports Server (NTRS)

Abushagur, Mustafa A. G. (Inventor); Ferguson, Cynthia K. (Inventor); Nordin, Gregory P. (Inventor); English, Jennifer M. (Inventor)

2007-01-01

A microscopic translation device for a microelectromechanical system includes a pair of linear stator assemblies disposed in spaced relation to define an elongate channel. Each assembly is formed by a plurality of stators arranged in a row along the channel. A shuttle member is disposed between the stator assemblies for translating movement along the channel. The shuttle member includes a plurality of rotors extending outwardly from opposite sides. The shuttle is grounded through the stator assemblies and includes a mounting area for an object to be translated. Electrical lines are individually connected to alternate stators of a plurality of groups of the stators. A current supply sequentially supplies current through the electrical lines to the alternate stators so as to effect charging of the stators in a predetermined sequence. This produces a tangential capacitive force that causes translation of the shuttle.

System and method for heating ferrite magnet motors for low temperatures

DOEpatents

Reddy, Patel Bhageerath; El-Refaie, Ayman Mohamed Fawzi; Huh, Kum-Kang

2017-07-04

A system and method for heating ferrite permanent magnets in an electrical machine is disclosed. The permanent magnet machine includes a stator assembly and a rotor assembly, with a plurality of ferrite permanent magnets disposed within the stator assembly or the rotor assembly to generate a magnetic field that interacts with a stator magnetic field to produce a torque. A controller of the electrical machine is programmed to cause a primary field current to be applied to the stator windings to generate the stator magnetic field, so as to cause the rotor assembly to rotate relative to the stator assembly. The controller is further programmed to cause a secondary current to be applied to the stator windings to selectively generate a secondary magnetic field, the secondary magnetic field inducing eddy currents in at least one of the stator assembly and the rotor assembly to heat the ferrite permanent magnets.

Influence of the rotor-stator interaction on the dynamic stresses of Francis runners

NASA Astrophysics Data System (ADS)

Guillaume, R.; Deniau, J. L.; Scolaro, D.; Colombet, C.

2012-11-01

Thanks to advances in computing capabilities and Computational Fluid Dynamics (CFD) techniques, it is now possible to calculate realistic unsteady pressure fields in Francis turbines. This paper will explain methods to calculate the structural loads and the dynamic behaviour in order to optimize the turbine design and maximize its reliability and lifetime. Depending on the operating conditions of a Francis turbine, different hydraulic phenomena may impact the mechanical behaviour of the structure. According to their nature, these highly variable phenomena should be treated differently and specifically in order to estimate the potential risks arising on submerged structures, in particular the runner. The operating condition studied thereafter is the point at maximum power with the maximum head. Under this condition, the runner is excited by only one dynamic phenomenon named the Rotor-Stator Interaction (RSI). The origin of the phenomenon is located on the radial gap of the turbine and is the source of pressure fluctuations. A fluid-structure analysis is performed to observe the influence of that dynamic pressure field on the runner behaviour. The first part of the paper deals with the unsteady fluid computation. The RSI phenomenon is totally unsteady so the fluid simulation must take into account the entire machine and its rotation movement, in order to obtain a dynamic pressure field. In the second part of the paper, a method suitable for the RSI study is developed. It is known that the fluctuating pressure in this gap can be described as a sum of spatial components. By evaluating these components in the CFD results and on the scale model, it is possible to assess the relevance of the numerical results on the whole runner. After this step, the numerical pressure field can be used as the dynamic load of the structure. The final part of the paper presentsthe mechanical finite element calculations. A modal analysis of the runner in water and a harmonic analysis of its

Vigilando la Calidad del Agua de los Grandes Rios de la Nacion: El Programa NASQAN del Rio Grande (Rio Bravo del Norte)

USGS Publications Warehouse

Lurry, Dee L.; Reutter, David C.; Wells, Frank C.; Rivera, M.C.; Munoz, A.

1998-01-01

La Oficina del Estudio Geologico de los Estados Unidos (U.S. Geological Survey, 0 USGS) ha monitoreado la calidad del agua de la cuenca del Rio Grande (Rio Bravo del Norte) desde 1995 como parte de la rediseiiada Red Nacional para Contabilizar la Calidad del Agua de los Rios (National Stream Quality Accounting Network, o NASOAN) (Hooper and others, 1997). EI programa NASOAN fue diseiiado para caracterizar las concentraciones y el transporte de sedimento y constituyentes quimicos seleccionados, encontrados en los grandes rios de los Estados Unidos - incluyendo el Misisipi, el Colorado y el Columbia, ademas del Rio Grande. En estas cuatro cuencas, el USGS opera actualmente (1998) una red de 40 puntos de muestreo pertenecientes a NASOAN, con un enfasis en cuantificar el flujo en masa (la cantidad de material que pasa por la estacion, expresado en toneladas por dial para cada constituyente. Aplicacando un enfoque consistente, basado en la cuantificacion de flujos en la cuenca del Rio Grande, el programa NASOAN esta generando la informacion necesaria para identificar fuentes regionales de diversos contaminantes, incluyendo sustancias qui micas agricolas y trazas elementos en la cuenca. EI efecto de las grandes reservas en el Rio Grande se puede observar segun los flujos de constituyentes discurren a 10 largo del rio. EI analisis de los flujos de constituyentes a escala de la cuenca proveera los medios para evaluar la influencia de la actividad humana sobre las condiciones de calidad del agua del Rio Grande.

System and method for heating ferrite magnet motors for low temperatures

DOE Office of Scientific and Technical Information (OSTI.GOV)

Reddy, Patel Bhageerath; El-Refaie, Ayman Mohamed Fawzi; Huh, Kum-Kang

A system and method for heating ferrite permanent magnets in an electrical machine is disclosed. The permanent magnet machine includes a stator assembly and a rotor assembly, with a plurality of ferrite permanent magnets disposed within the stator assembly or the rotor assembly to generate a magnetic field that interacts with a stator magnetic field to produce a torque. A controller of the electrical machine is programmed to cause a primary field current to be applied to the stator windings to generate the stator magnetic field, so as to cause the rotor assembly to rotate relative to the stator assembly.more » The controller is further programmed to cause a secondary current to be applied to the stator windings to selectively generate a secondary magnetic field, the secondary magnetic field inducing eddy currents in at least one of the stator assembly and the rotor assembly to heat the ferrite permanent magnets.« less

Vane clocking effects in an embedded compressor stage

NASA Astrophysics Data System (ADS)

Key, Nicole Leanne

The objective of this research was to experimentally investigate the effects of vane clocking, the circumferential indexing of adjacent vane rows with similar vane counts, in an embedded compressor stage. Experiments were performed in the Purdue 3-Stage Compressor, which consists of an IGV followed by three stages. The IGV, Stator 1, and Stator 2 have identical vane counts of 44, and the effects of clocking were studied on Stage 2. The clocking configuration that located the upstream vane wake on the Stator 2 leading edge was identified with total pressure measurements at the inlet to Stator 2 and confirmed with measurements at the exit of Stator 2. For both loading conditions, the total temperature results showed that there was no measurable change associated with vane clocking in the amount of work done on the flow. At design loading, the change in stage efficiency with vane clocking was 0.27 points between the maximum and minimum efficiency clocking configurations. The maximum efficiency configuration was the case where the Stator 1 wake impinged on the Stator 2 leading edge. This condition produced a shallower and thinner Stator 2 wake compared to the clocking configuration that located the wake in the middle of the Stator 2 passage. By locating the Stator 1 wake at the leading edge, it dampened the Stator 2 boundary layer response to inlet fluctuations associated with the Rotor 2 wakes. At high loading, the change in Stage 2 efficiency increased to 1.07 points; however, the maximum efficiency clocking configuration was the case where the Stator 1 wake passed through the middle of the downstream vane passage. At high loading, the flow physics associated with vane clocking were different than at design loading because the location of the Stator 1 wake fluid on the Stator 2 leading edge triggered a boundary layer separation on the suction side of Stator 2 producing a wider and deeper wake. Vane clocking essentially affects the amount of interaction between the

Horizontal wind powered reaction turbine electrical generator

DOE Office of Scientific and Technical Information (OSTI.GOV)

de Geus, A.M.

1980-05-27

A horizontal wind powered electrical generator is disclosed in which a horizontal reaction turbine is disposed within an augmentor cowling which extends downwind of the turbine. First stage curved stator blades interconnect the augmentor with the turbine cowling, and secondary stator blades are spaced downwind from said primary stator blades to extend inwardly from the augmentor to terminate short of the turbine cowling. These secondary stator blades have a greater angle of departure than the primary stator blades to increase the rotational velocity of the air at the expense of its axial velocity while permitting the axial velocity of themore » air moving inwardly of the secondary stator blades to be undiminished. A venturi-structured diffusor is carried by said augmentor in a downwind position to lower the pressure generally and assist the action of the secondary stator blades.« less

Hybrid-fuel bacterial flagellar motors in Escherichia coli

PubMed Central

Sowa, Yoshiyuki; Homma, Michio; Ishijima, Akihiko; Berry, Richard M.

2014-01-01

The bacterial flagellar motor rotates driven by an electrochemical ion gradient across the cytoplasmic membrane, either H+ or Na+ ions. The motor consists of a rotor ∼50 nm in diameter surrounded by multiple torque-generating ion-conducting stator units. Stator units exchange spontaneously between the motor and a pool in the cytoplasmic membrane on a timescale of minutes, and their stability in the motor is dependent upon the ion gradient. We report a genetically engineered hybrid-fuel flagellar motor in Escherichia coli that contains both H+- and Na+-driven stator components and runs on both types of ion gradient. We controlled the number of each type of stator unit in the motor by protein expression levels and Na+ concentration ([Na+]), using speed changes of single motors driving 1-μm polystyrene beads to determine stator unit numbers. De-energized motors changed from locked to freely rotating on a timescale similar to that of spontaneous stator unit exchange. Hybrid motor speed is simply the sum of speeds attributable to individual stator units of each type. With Na+ and H+ stator components expressed at high and medium levels, respectively, Na+ stator units dominate at high [Na+] and are replaced by H+ units when Na+ is removed. Thus, competition between stator units for spaces in a motor and sensitivity of each type to its own ion gradient combine to allow hybrid motors to adapt to the prevailing ion gradient. We speculate that a similar process may occur in species that naturally express both H+ and Na+ stator components sharing a common rotor. PMID:24550452

Fan noise reduction achieved by removing tip flow irregularities behind the rotor - forward arc test configurations

NASA Technical Reports Server (NTRS)

Dittmar, J. H.; Woodward, R. P.; Mackinnon, M. J.

1984-01-01

The noise source caused by the interaction of the rotor tip flow irregularities (vortices and velocity defects) with the downstream stator vanes was studied. Fan flow was removed behind a 0.508 meter (20 in.) diameter model turbofan through an outer wall slot between the rotor and stator. Noise measurements were made with far-field microphones positioned in an arc about the fan inlet and with a pressure transducer in the duct behind the stator. Little tone noise reduction was observed in the forward arc during flow removal; possibly because the rotor-stator interaction noise did not propagate upstream through the rotor. Noise reductions were maded in the duct behind the stator and the largest decrease occurred with the first increment of flow removal. This result indicates that the rotor tip flow irregularity-stator interaction is as important a noise producing mechanism as the normally considered rotor wake-stator interaction.

A new standing-wave-type linear ultrasonic motor based on in-plane modes.

PubMed

Shi, Yunlai; Zhao, Chunsheng

2011-05-01

This paper presents a new standing-wave-type linear ultrasonic motor using combination of the first longitudinal and the second bending modes. Two piezoelectric plates in combination with a metal thin plate are used to construct the stator. The superior point of the stator is its isosceles triangular structure part of the stator, which can amplify the displacement in horizontal direction of the stator in perpendicular direction when the stator is operated in the first longitudinal mode. The influence of the base angle θ of the triangular structure part on the amplitude of the driving foot has been analyzed by numerical analysis. Four prototype stators with different angles θ have been fabricated and the experimental investigation of these stators has validated the numerical simulation. The overall dimensions of the prototype stators are no more than 40 mm (length) × 20 mm (width) × 5 mm (thickness). Driven by an AC signal with the driving frequency of 53.3 kHz, the no-load speed and the maximal thrust of the prototype motor using the stator with base angle 20° were 98 mm/s and 3.2N, respectively. The effective elliptical motion trajectory of the contact point of the stator can be achieved by the isosceles triangular structure part using only two PZTs, and thus it makes the motor low cost in fabrication, simple in structure and easy to realize miniaturization. Copyright © 2010 Elsevier B.V. All rights reserved.

Radio-Observaciones del OH EN la Coma del Cometa Halley Desde EL Hemisferio Sur

NASA Astrophysics Data System (ADS)

Silva, A. M.; Bajaja, E.; Morras, R.; Cersosimo, J. C.; Martin, M. C.; Arnal, E. M.; Poppel, W. G. L.; Colomb, F. R.; Mazzaro, J.; Olalde, J. C.; Boriakoff, V.; Mirabel, I. F.

1987-05-01

Se utilizó una antena de 30 metros del Instituto Argentino de Radioastronomía para observaciones diarias Cf ebrero a abril de 1986) de la transición en 1667 MHz ( λ = 18 cm) del OH en la coma del cometa Halley. De las observaciones realizadas se concluye: 1) El número promedio de moléculas de OH en la coma durante 37 días de observación fue de (8.9±3.5)x1034 moléculas, lo que implica una tasa de producción promedio de OH de 1.8x1029 moléculas seg-1 y consecuentemente una pérdida de masa promedio de 17±6 toneladas seg-1 . Este valor está de acuerdo con las mediciones realizadas por las sondas Vega y Giotto. 2) El monitoreo desde el lAR revela la existencia de variaciones bruscas en los flujos de absorción del OH. Estas variaciones son consistentes con los modelos que representan la producción gaseosa a partir de ejecciones y/o desprendimientos discretos de materia congelada del núcleo. 3) Las variaciones en la densidad de flujo son consistentes con las estimaciones de los tiem- pos de vida medios del H2O y del OH en presencia del campo de radiación solar. 4) Se encuentra una correlación entre la intensidad del flujo absorbido y anisotropías en Ia dinamica de la coma.

Reliability and Confidence Interval Analysis of a CMC Turbine Stator Vane

NASA Technical Reports Server (NTRS)

Murthy, Pappu L. N.; Gyekenyesi, John P.; Mital, Subodh K.

2008-01-01

an economical manner. The methods to accurately determine the service life of an engine component with associated variability have become increasingly difficult. This results, in part, from the complex missions which are now routinely considered during the design process. These missions include large variations of multi-axial stresses and temperatures experienced by critical engine parts. There is a need for a convenient design tool that can accommodate various loading conditions induced by engine operating environments, and material data with their associated uncertainties to estimate the minimum predicted life of a structural component. A probabilistic composite micromechanics technique in combination with woven composite micromechanics, structural analysis and Fast Probability Integration (FPI) techniques has been used to evaluate the maximum stress and its probabilistic distribution in a CMC turbine stator vane. Furthermore, input variables causing scatter are identified and ranked based upon their sensitivity magnitude. Since the measured data for the ceramic matrix composite properties is very limited, obtaining a probabilistic distribution with their corresponding parameters is difficult. In case of limited data, confidence bounds are essential to quantify the uncertainty associated with the distribution. Usually 90 and 95% confidence intervals are computed for material properties. Failure properties are then computed with the confidence bounds. Best estimates and the confidence bounds on the best estimate of the cumulative probability function for R-S (strength - stress) are plotted. The methodologies and the results from these analyses will be discussed in the presentation.

Torque ripple reduction in electric machines

DOE Office of Scientific and Technical Information (OSTI.GOV)

Reddy, Patel Bhageerath; Huh, Kum-Kang; El-Refaie, Ayman Mohamed Fawzi

An electric machine, such as an Internal Permanent magnet or Synchronous Reluctance machine, having X phases, that includes a stator assembly, having M slots, with a stator core and stator teeth, that is further configured with stator windings to generate a stator magnetic field when excited with alternating currents and extends along a longitudinal axis with an inner surface that defines a cavity; and a rotor assembly, having N poles, disposed within the cavity which is configured to rotate about the longitudinal axis, wherein the rotor assembly includes a shaft, a rotor core located circumferentially around the shaft. The machinemore » is configured such that a value k=M/(X*N) wherein k is a non-integer greater than about 1.3. The electric machine may alternatively, or additionally, include a non-uniformed gap between the exterior surface of the rotor spokes and the interior stator surface of the stator.« less

Disc rotors with permanent magnets for brushless DC motor

DOEpatents

Hawsey, Robert A.; Bailey, J. Milton

1992-01-01

A brushless dc permanent magnet motor drives an autonomous underwater vehe. In one embodiment, the motor comprises four substantially flat stators in stacked relationship, with pairs of the stators axially spaced, each of the stators comprising a tape-wound stator coil, and first and second substantially flat rotors disposed between the spaced pairs of stators. Each of the rotors includes an annular array of permanent magnets embedded therein. A first shaft is connected to the first rotor and a second, concentric shaft is connected to the second rotor, and a drive unit causes rotation of the two shafts in opposite directions. The second shaft comprises a hollow tube having a central bore in which the first shaft is disposed. Two different sets of bearings support the first and second shafts. In another embodiment, the motor comprises two ironless stators and pairs of rotors mounted on opposite sides of the stators and driven by counterrotating shafts.

Dovetail spoke internal permanent magnet machine

DOEpatents

Alexander, James Pellegrino [Ballston Lake, NY; EL-Refaie, Ayman Mohamed Fawzi [Niskayuna, NY; Lokhandwalla, Murtuza [Clifton Park, NY; Shah, Manoj Ramprasad [Latham, NY; VanDam, Jeremy Daniel [West Coxsackie, NY

2011-08-23

An internal permanent magnet (IPM) machine is provided. The IPM machine includes a stator assembly and a stator core. The stator core also includes multiple stator teeth. The stator assembly is further configured with stator windings to generate a stator magnetic field when excited with alternating currents and extends along a longitudinal axis with an inner surface defining a cavity. The IPM machine also includes a rotor assembly and a rotor core. The rotor core is disposed inside the cavity and configured to rotate about the longitudinal axis. The rotor assembly further includes a shaft. The shaft further includes multiple protrusions alternately arranged relative to multiple bottom structures provided on the shaft. The rotor assembly also includes multiple stacks of laminations disposed on the protrusions and dovetailed circumferentially around the shaft. The rotor assembly further includes multiple pair of permanent magnets for generating a magnetic field, which magnetic field interacts with the stator magnetic field to produce a torque. The multiple pair of permanent magnets are disposed between the stacks. The rotor assembly also includes multiple middle wedges mounted between each pair of the multiple permanent magnets.

Espectroscopia del Cometa Halley

NASA Astrophysics Data System (ADS)

Naranjo, O.; Fuenmayor, F.; Ferrin, L.; Bulka, P.; Mendoza, C.

1987-05-01

Se reportan observaciones espectroscópicas del cometa Halley. Los espectros fueron tomados usando el espectrógrafo del telescopio reflector de 1 metro del Observatorio Nacional de Venezuela. Se utilizó óptica azul, con una red de difracción de 600 lineas/min, obteniéndose una dispersión de 74.2 A/mm y una resolución de 2.5 A, en el rango espectral de 3500 a 6500 A. Seis placas fueron tomadas con emulsión IIa-O y dos con IIa-D. Los tiempos de exposición fueron entre 10 y 150 minutos. El cometa se encontraba entre 0.70 y 1.04 UA del Sol, y entre 1.28 y 0.73 UA de la Tierra. Las emisiones más prominentes en el espectro, son las del CN, C2, y C3. Otras emisiones detectadas corresponden a CH, NH2 y Na. Los espectros muestran un fuerte continuo, indicando un contenido significativo de polvo. Se detectó mayor intensidad del contínuo, en la dirección anti solar, lo cual es evidencia de la cola de polvo.

Levitated Duct Fan (LDF) Aircraft Auxiliary Generator

NASA Technical Reports Server (NTRS)

Eichenberg, Dennis J.; Emerson, Dawn C.; Gallo, Christopher A.; Thompson, William K.

2011-01-01

This generator concept includes a novel stator and rotor architecture made from composite material with blades attached to the outer rotating shell of a ducted fan drum rotor, a non-contact support system between the stator and rotor using magnetic fields to provide levitation, and an integrated electromagnetic generation system. The magnetic suspension between the rotor and the stator suspends and supports the rotor within the stator housing using permanent magnets attached to the outer circumference of the drum rotor and passive levitation coils in the stator shell. The magnets are arranged in a Halbach array configuration.

Intertextual Sexual Politics: Illness and Desire in Enrique Gomez Carrillo's "Del amor", "del dolor y del vicio" and Aurora Caceres's "La rosa muerta"

ERIC Educational Resources Information Center

LaGreca, Nancy

2012-01-01

This study explores the intertextuality between Aurora Caceres's "La rosa muerta" (1914) and the novel "Del amor, del dolor y del vicio" (1898) by her ex-husband, Enrique Gomez Carrillo. Caceres strategically mentions Gomez Carrillo's novel in "La rosa muerta" to invite a reading of her work in dialogue with his. Both narratives follow the sexual…

A novel contact model of piezoelectric traveling wave rotary ultrasonic motors with the finite volume method.

PubMed

Renteria-Marquez, I A; Renteria-Marquez, A; Tseng, B T L

2018-06-06

The operating principle of the piezoelectric traveling wave rotary ultrasonic motor is based on two energy conversion processes: the generation of the stator traveling wave and the rectification of the stator movement through the stator-rotor contact mechanism. This paper presents a methodology to model in detail the stator-rotor contact interface of these motors. A contact algorithm that couples a model of the stator which is discretized with the finite volume method and an analytical model of the rotor is presented. The outputs of the proposed model are the normal and tangential force distribution produced at the stator-rotor contact interface, contact length, height and shape of the stator traveling wave and rotor speed. The torque-speed characteristic of the USR60 is calculated with the proposed model, and the results of the model are compared versus the real torque-speed of the motor. A good agreement between the proposed model results and the torque-speed characteristic of the USR60 was observed. Copyright © 2018 Elsevier B.V. All rights reserved.

Extended core for motor/generator

DOEpatents

Shoykhet, Boris A.

2005-05-10

An extended stator core in a motor/generator can be utilized to mitigate losses in end regions of the core and a frame of the motor/generator. To mitigate the losses, the stator core can be extended to a length substantially equivalent to or greater than a length of a magnetically active portion in the rotor. Alternatively, a conventional length stator core can be utilized with a shortened magnetically active portion to mitigate losses in the motor/generator. To mitigate the losses in the core caused by stator winding, the core can be extended to a length substantially equivalent or greater than a length of stator winding.

Extended core for motor/generator

DOEpatents

Shoykhet, Boris A.

2006-08-22

An extended stator core in a motor/generator can be utilized to mitigate losses in end regions of the core and a frame of the motor/generator. To mitigate the losses, the stator core can be extended to a length substantially equivalent to or greater than a length of a magnetically active portion in the rotor. Alternatively, a conventional length stator core can be utilized with a shortened magnetically active portion to mitigate losses in the motor/generator. To mitigate the losses in the core caused by stator winding, the core can be extended to a length substantially equivalent or greater than a length of stator winding.

Monocoil reciprocating permanent magnet electric machine with self-centering force

NASA Technical Reports Server (NTRS)

Bhate, Suresh K. (Inventor); Vitale, Nicholas G. (Inventor)

1989-01-01

A linear reciprocating machine has a tubular outer stator housing a coil, a plunger and an inner stator. The plunger has four axially spaced rings of radially magnetized permanent magnets which cooperate two at a time with the stator to complete first or second opposite magnetic paths. The four rings of magnets and the stators are arranged so that the stroke of the plunger is independent of the axial length of the coil.

ACCELEROMETER

DOEpatents

Pope, K.E.

1958-11-25

A device, commonly known as an accelerometer, is described which may be utllized for measuring acceleratlon with high sensitivity and accuracy tbroughout a relatively wlde range of values. In general, the accelerometer consists of an assembly, including an electric motor stator and a mass element located away from the axis of rotation of the stator, rotatably mounted on a support, and an electric motor rotor positioned within the stator and rotatable thereln. An electrlcal switching circuit controlled by the movement of the stator lntermittently energizes the rotor winding and retards move ment of the stator, and a centrifugal switch is rotatable with the rotor to operate upon attainment of a predetermined rotor rotational velocity.

Combination radial and thrust magnetic bearing

NASA Technical Reports Server (NTRS)

Blumenstock, Kenneth A. (Inventor)

2002-01-01

A combination radial and thrust magnetic bearing is disclosed that allows for both radial and thrust axes control of an associated shaft. The combination radial and thrust magnetic bearing comprises a rotor and a stator. The rotor comprises a shaft, and first and second rotor pairs each having respective rotor elements. The stator comprises first and second stator elements and a magnet-sensor disk. In one embodiment, each stator element has a plurality of split-poles and a corresponding plurality of radial force coils and, in another embodiment, each stator element does not require thrust force coils, and radial force coils are replaced by double the plurality of coils serving as an outer member of each split-pole half.

In vivo evaluation of zirconia ceramic in the DexAide right ventricular assist device journal bearing.

PubMed

Saeed, Diyar; Shalli, Shanaz; Fumoto, Hideyuki; Ootaki, Yoshio; Horai, Tetsuya; Anzai, Tomohiro; Zahr, Roula; Horvath, David J; Massiello, Alex L; Chen, Ji-Feng; Dessoffy, Raymond; Catanese, Jacquelyn; Benefit, Stephen; Golding, Leonard A R; Fukamachi, Kiyotaka

2010-06-01

Zirconia is a ceramic with material properties ideal for journal bearing applications. The purpose of this study was to evaluate the use of zirconium oxide (zirconia) as a blood journal bearing material in the DexAide right ventricular assist device. Zirconia ceramic was used instead of titanium to manufacture the DexAide stator housing without changing the stator geometry or the remaining pump hardware components. Pump hydraulic performance, journal bearing reliability, biocompatibility, and motor efficiency data of the zirconia stator were evaluated in six chronic bovine experiments for 14-91 days and compared with data from chronic experiments using the titanium stator. Pump performance data including average in vivo pump flows and speeds using a zirconia stator showed no statistically significant difference to the average values for 16 prior titanium stator in vivo studies, with the exception of a 19% reduction in power consumption. Indices of hemolysis were comparable for both stator types. Results of coagulation assays and platelet aggregation tests for the zirconia stator implants showed no device-induced increase in platelet activation. Postexplant evaluation of the zirconia journal bearing surfaces showed no biologic deposition in any of the implants. In conclusion, zirconia ceramic can be used as a hemocompatible material to improve motor efficiency while maintaining hydraulic performance in a blood journal bearing application.

High speed internal permanent magnet machine and method of manufacturing the same

DOEpatents

Alexander, James Pellegrino [Ballston Lake, NY; EL-Refaie, Ayman Mohamed Fawzi [Niskayuna, NY; Lokhandwalla, Murtuza [Clifton Park, NY; Shah, Manoj Ramprasad [Latham, NY; VanDam, Jeremy Daniel [West Coxsackie, NY

2011-09-13

An internal permanent magnet (IPM) machine is provided. The IPM machine includes a stator assembly and a stator core. The stator core also includes multiple stator teeth. The stator assembly is further configured with stator windings to generate a magnetic field when excited with alternating currents and extends along a longitudinal axis with an inner surface defining a cavity. The IPM machine also includes a rotor assembly and a rotor core. The rotor core is disposed inside the cavity and configured to rotate about the longitudinal axis. The rotor assembly further includes a shaft. The shaft further includes multiple protrusions alternately arranged relative to multiple bottom structures provided on the shaft. The rotor assembly also includes multiple stacks of laminations disposed on the protrusions and dovetailed circumferentially around the shaft. The rotor assembly further includes multiple permanent magnets for generating a magnetic field, which interacts with the stator magnetic field to produce torque. The permanent magnets are disposed between the stacks. The rotor assembly also includes multiple bottom wedges disposed on the bottom structures of the shaft and configured to hold the multiple stacks and the multiple permanent magnets.

Examination of Sandwich-Type Multidegree-of-Freedom Spherical Ultrasonic Motor

NASA Astrophysics Data System (ADS)

Lu, Bo; Aoyagi, Manabu; Takano, Takehiro; Tamura, Hideki

2010-07-01

A sandwich-type multidegree-of-freedom (MDOF) spherical ultrasonic motor (SUSM) is newly proposed. The motor consists of a spherical rotor and two stator vibrators holding the rotor. This structure has both a rotor support and a preload mechanism. The stator excites five vibration modes, and the rotor can rotate on three axes. An experiment of a torque composition of two stators was carried out. The contact surface between the rotor and the stators forms a spherical surface. Moreover, a displacement magnification mechanism, which was used in the former model to rotate on the Z-axis, is no longer necessary. Hence the stator is simpler in construction than the former model. In this paper, we describe the construction and the operating principle of the MDOF ultrasonic motor, modal analysis results for the stator, and some measurement results from trial manufacturing. The miniaturization of the motor and increase in torque were successfully realized.

Surface Temperature Measurements from a Stator Vane Doublet in a Turbine Engine Afterburner Flame Using a YAG:Tm Thermographic Phosphor

NASA Technical Reports Server (NTRS)

Eldridge, J. I.; Walker, D. G.; Gollub, S. L.; Jenkins, T. P.; Allison, S. W.

2015-01-01

Luminescence-based surface temperature measurements were obtained from a YAG:Tm-coated stator vane doublet exposed to the afterburner flame of a J85 test engine at University of Tennessee Space Institute (UTSI). The objective of the testing was to demonstrate that reliable surface temperatures based on luminescence decay of a thermographic phosphor producing short-wavelength emission could be obtained from the surface of an actual engine component in a high gas velocity, highly radiative afterburner flame environment. YAG:Tm was selected as the thermographic phosphor for its blue emission at 456 nm (1D23F4 transition) and UV emission at 365 nm (1D23H6 transition) because background thermal radiation is lower at these wavelengths, which are shorter than those of many previously used thermographic phosphors. Luminescence decay measurements were acquired using a probe designed to operate in the afterburner flame environment. The probe was mounted on the sidewall of a high-pressure turbine vane doublet from a Honeywell TECH7000 turbine engine coated with a standard electron-beam physical vapor deposited (EB-PVD) 200-m-thick TBC composed of yttria-stabilized zirconia (YSZ) onto which a 25-m-thick YAG:Tm thermographic phosphor layer was deposited by solution precursor plasma spray (SPPS). Spot temperature measurements were obtained by measuring luminescence decay times at different afterburner power settings and then converting decay time to temperature via calibration curves. Temperature measurements using the decays of the 456 and 365 nm emissions are compared. While successful afterburner environment measurements were obtained to about 1300C with the 456 nm emission, successful temperature measurements using the 365 nm emission were limited to about 1100C due to interference by autofluorescence of probe optics at short decay times.

Crystallographic and Molecular Dynamics Analysis of Loop Motions Unmasking the Peptidoglycan-Binding Site in Stator Protein MotB of Flagellar Motor

PubMed Central

Nahar, Musammat F.; Buckle, Ashley M.; Roujeinikova, Anna

2011-01-01

Background The C-terminal domain of MotB (MotB-C) shows high sequence similarity to outer membrane protein A and related peptidoglycan (PG)-binding proteins. It is believed to anchor the power-generating MotA/MotB stator unit of the bacterial flagellar motor to the peptidoglycan layer of the cell wall. We previously reported the first crystal structure of this domain and made a puzzling observation that all conserved residues that are thought to be essential for PG recognition are buried and inaccessible in the crystal structure. In this study, we tested a hypothesis that peptidoglycan binding is preceded by, or accompanied by, some structural reorganization that exposes the key conserved residues. Methodology/Principal Findings We determined the structure of a new crystalline form (Form B) of Helicobacter pylori MotB-C. Comparisons with the existing Form A revealed conformational variations in the petal-like loops around the carbohydrate binding site near one end of the β-sheet. These variations are thought to reflect natural flexibility at this site required for insertion into the peptidoglycan mesh. In order to understand the nature of this flexibility we have performed molecular dynamics simulations of the MotB-C dimer. The results are consistent with the crystallographic data and provide evidence that the three loops move in a concerted fashion, exposing conserved MotB residues that have previously been implicated in binding of the peptide moiety of peptidoglycan. Conclusion/Significance Our structural analysis provides a new insight into the mechanism by which MotB inserts into the peptidoglycan mesh, thus anchoring the power-generating complex to the cell wall. PMID:21533052

33 CFR 80.1118 - Marina Del Rey, CA.

Code of Federal Regulations, 2010 CFR

2010-07-01

... NAVIGATION RULES COLREGS DEMARCATION LINES Pacific Coast § 80.1118 Marina Del Rey, CA. (a) A line drawn from Marina Del Rey Breakwater South Light 1 to Marina Del Rey Light 4. (b) A line drawn from Marina Del Rey... 33 Navigation and Navigable Waters 1 2010-07-01 2010-07-01 false Marina Del Rey, CA. 80.1118...

33 CFR 80.1118 - Marina Del Rey, CA.

Code of Federal Regulations, 2012 CFR

2012-07-01

... NAVIGATION RULES COLREGS DEMARCATION LINES Pacific Coast § 80.1118 Marina Del Rey, CA. (a) A line drawn from Marina Del Rey Breakwater South Light 1 to Marina Del Rey Light 4. (b) A line drawn from Marina Del Rey... 33 Navigation and Navigable Waters 1 2012-07-01 2012-07-01 false Marina Del Rey, CA. 80.1118...

33 CFR 80.1118 - Marina Del Rey, CA.

Code of Federal Regulations, 2013 CFR

2013-07-01

... NAVIGATION RULES COLREGS DEMARCATION LINES Pacific Coast § 80.1118 Marina Del Rey, CA. (a) A line drawn from Marina Del Rey Breakwater South Light 1 to Marina Del Rey Light 4. (b) A line drawn from Marina Del Rey... 33 Navigation and Navigable Waters 1 2013-07-01 2013-07-01 false Marina Del Rey, CA. 80.1118...

33 CFR 80.1118 - Marina Del Rey, CA.

Code of Federal Regulations, 2011 CFR

2011-07-01

... NAVIGATION RULES COLREGS DEMARCATION LINES Pacific Coast § 80.1118 Marina Del Rey, CA. (a) A line drawn from Marina Del Rey Breakwater South Light 1 to Marina Del Rey Light 4. (b) A line drawn from Marina Del Rey... 33 Navigation and Navigable Waters 1 2011-07-01 2011-07-01 false Marina Del Rey, CA. 80.1118...

33 CFR 80.1118 - Marina Del Rey, CA.

Code of Federal Regulations, 2014 CFR

2014-07-01

... NAVIGATION RULES COLREGS DEMARCATION LINES Pacific Coast § 80.1118 Marina Del Rey, CA. (a) A line drawn from Marina Del Rey Breakwater South Light 1 to Marina Del Rey Light 4. (b) A line drawn from Marina Del Rey... 33 Navigation and Navigable Waters 1 2014-07-01 2014-07-01 false Marina Del Rey, CA. 80.1118...

Piezoelectric wave motor

DOEpatents

Yerganian, Simon Scott

2001-07-17

A piezoelectric motor having a stator in which piezoelectric elements are contained in slots formed in the stator transverse to the desired wave motion. When an electric field is imposed on the elements, deformation of the elements imposes a force perpendicular to the sides of the slot, deforming the stator. Appropriate frequency and phase shifting of the electric field will produce a wave in the stator and motion in a rotor. In a preferred aspect, the piezoelectric elements are configured so that deformation of the elements in direction of an imposed electric field, generally referred to as the d.sub.33 direction, is utilized to produce wave motion in the stator. In a further aspect, the elements are compressed into the slots so as to minimize tensile stresses on the elements in use.

Piezoelectric wave motor

DOEpatents

Yerganian, Simon Scott

2003-02-11

A piezoelectric motor having a stator in which piezoelectric elements are contained in slots formed in the stator transverse to the desired wave motion. When an electric field is imposed on the elements, deformation of the elements imposes a force perpendicular to the sides of the slot, deforming the stator. Appropriate frequency and phase-shifting of the electric field will produce a wave in the stator and motion in a rotor. In a preferred aspect, the piezoelectric elements are configured so that deformation of the elements in the direction of an imposed electric field, generally referred to as the d.sub.33 direction, is utilized to produce wave motion in the stator. In a further aspect, the elements are compressed into the slots so as to minimize tensile stresses on the elements in use.

SSME Seal Test Program: Test results for sawtooth pattern damper seal

NASA Technical Reports Server (NTRS)

Childs, D. W.

1986-01-01

Direct and transverse force coefficients for 11, sawtooth-pattern, and damper-seal configurations were examined. The designation damper seal uses a deliberately roughened stator and smooth rotor to increase the net damping force developed by a seal. The designation sawtooth-pattern refers to a stator roughness pattern. The sawtooth pattern yields axial grooves in the stator which are interrupted by spacer elements which act as flow constrictions or dams. All seals use the same smooth rotor and have the same, constant, minimum clearance. The stators examined the consequences of changes in the following design parameters: (1) axial-groove depth; (2) number of teeth: (3) number of sawtooth sections; (4) number of spacer elements; (5) dam width; (6) axially aligned sawtooth sections versus axially-staggered sawtooth sections; and (7) groove geometry. It is found that none of the sawtooth-pattern seal performs as well as the best round-hole-pattern seal. Maximum damping configurations for the sawtooth and round-hole-pattern stators have comparable stiffness performance. Several of the sawtooth pattern stators outperformed the best round-hole pattern seal.

An experimental study on the effects of blade row interactions on aerodynamic loss mechanisms in a multistage compressor

NASA Astrophysics Data System (ADS)

Smith, Natalie Rochelle

While the gas turbine engine has existed for nearly 80 years, much of the complex aerodynamics which governs compressor performance is still not well understood. The unsteady flow field consists of periodic blade row interactions from the wakes and potential fields of each blade and vane. Vane clocking is the relative circumferential indexing of adjacent vane rows with the same vane count, and it is one method to change blade row interactions. Though the potential of performance benefits with vane clocking is known, the driving flow physics have yet to be identified. This research examines the effects of blade row interactions on embedded stator total pressure loss and boundary layer transition in the Purdue 3-stage axial compressor. The inlet guide vane, Stator 1, and Stator 2 all have 44 vanes which enable vane clocking of the embedded stage, while the rotors have different blade counts producing amplitude modulation of the unsteady interactions. A detailed investigation of corrected conditions is presented to establish repeatable, compressor performance year-round in a facility utilizing ambient inlet conditions. Without proper humidity accounting of compressor corrected conditions and an understanding of the potential for inlet temperature changes to affect clearances due to thermal growth, measurements of small performance changes in detailed research studies could be indiscernible. The methodology and implementation of a powder-paint flow visualization technique along with the illuminated flow physics are presented in detail. This method assists in understanding the loss development in the compressor by highlighting stator corner separations and endwall flow patterns. Effects of loading condition, rotor tip clearance height, and stator wake and rotor tip leakage interactions are shown with this technique. Vane clocking effects on compressor performance were quantified for nine loading conditions and six clocking configurations - the largest vane clocking

Manual del McVCO 1999

USGS Publications Warehouse

McChesney, P.J.

1999-01-01

El McVCO es un generador de frecuencias basado en un microcontrolador que reemplaza al oscilador controlado por voltaje (VCO) utilizado en telemetría analógica de datos sísmicas. Acepta señales de baja potencia desde un sismómetro y produce una señal subportadora modulada en frecuencia adecuada para enlaces telefónicos o vía radio a un lugar remoto de recolección de datos. La frecuencia de la subportadora y la ganancia pueden ser seleccionadas mediante un interruptor. Tiene la opción de poder operar con dos canales para la observación con ganancia alta y baja. El McVCO fue diseñado con el propósito de mejorar la telemetría analógica de las señales dentro de la Pacific Northwest Seismograph Network (PNSN) (Red Sismográfica del Noroeste del Pacífico). Su desarrollo recibió el respaldo del Programa de Geofísica de la Universidad de Washington y del "Volcano Hazards and Earthquake Hazards programs of the United States Geological Survey (USGS) (Programa de Investigaciones de Riesgos Volcánicos y Programa de Investigaciones de Riesgos Sísmicos de los EEUU). Cientos de instrumentos se han construido e instalado. Además de utilizarlo el PNSN, el McVCO es usado por el Observatorio Vulcanológico de Alaska para monitorear los volcanes aleutianos y por el USGS Volcano Disaster Assistance Program (Programa de Ayuda en las Catástrofes Volcánicas del USGS) para responder a crisis volcánicas en otros países. Este manual cubre el funcionamiento del McVCO, es una referencia técnica para aquellos que necesitan saber con más detalle cómo funciona el McVCO, y cubre una serie de temas que requieren un trato explícito o que derivan del despliegue del instrumento.

Load-dependent assembly of the bacterial flagellar motor.

PubMed

Tipping, Murray J; Delalez, Nicolas J; Lim, Ren; Berry, Richard M; Armitage, Judith P

2013-08-20

It is becoming clear that the bacterial flagellar motor output is important not only for bacterial locomotion but also for mediating the transition from liquid to surface living. The output of the flagellar motor changes with the mechanical load placed on it by the external environment: at a higher load, the motor runs more slowly and produces higher torque. Here we show that the number of torque-generating units bound to the flagellar motor also depends on the external mechanical load, with fewer stators at lower loads. Stalled motors contained at least as many stators as rotating motors at high load, indicating that rotation is unnecessary for stator binding. Mutant stators incapable of generating torque could not be detected around the motor. We speculate that a component of the bacterial flagellar motor senses external load and mediates the strength of stator binding to the rest of the motor. The transition between liquid living and surface living is important in the life cycles of many bacteria. In this paper, we describe how the flagellar motor, used by bacteria for locomotion through liquid media and across solid surfaces, is capable of adjusting the number of bound stator units to better suit the external load conditions. By stalling motors using external magnetic fields, we also show that rotation is not required for maintenance of stators around the motor; instead, torque production is the essential factor for motor stability. These new results, in addition to previous data, lead us to hypothesize that the motor stators function as mechanosensors as well as functioning as torque-generating units.

Ácaros del mango

USDA-ARS?s Scientific Manuscript database

Los ácaros constituyen un grupo abundante y diverso que ocupa diferentes hábitats en árboles frutales y la estructura y disposición del follaje y ramas del mango, contribuyen significativamente a que se presente gran diversidad de ácaros benéficos y dañinos asociados a esta especie frutal. En Colomb...

Study on a New Combination Method and High Efficiency Outer Rotor Type Permanent Magnet Motors

NASA Astrophysics Data System (ADS)

Enomoto, Yuji; Kitamura, Masashi; Motegi, Yasuaki; Andoh, Takashi; Ochiai, Makoto; Abukawa, Toshimi

The segment stator core, high space factor coil, and high efficiency magnet are indispensable technologies in the development of compact and a high efficiency motors. But adoption of the segment stator core and high space factor coil has not progressed in the field of outer rotor type motors, for the reason that the inner components cannot be laser welded together. Therefore, we have examined a segment stator core combination technology for the purposes of getting a large increase in efficiency and realizing miniaturization. We have also developed a characteristic estimation method which provides the most suitable performance for segment stator core motors.

Single phase two pole/six pole motor

DOEpatents

Kirschbaum, Herbert S.

1984-01-01

A single phase alternating current two pole/six pole motor is provided with a main stator winding having six coils disposed unequally around the periphery of the machine. These coils are divided into two groups. When these groups are connected such that their magnetomotive forces are additive, two pole motor operation results. When the polarity of one of the groups is then reversed, six pole motor operation results. An auxiliary stator winding which is similar to the main stator winding is displaced from the main stator winding by 90 electrical degrees on a two pole basis.

Single phase two pole/six pole motor

DOEpatents

Kirschbaum, H.S.

1984-09-25

A single phase alternating current two pole/six pole motor is provided with a main stator winding having six coils disposed unequally around the periphery of the machine. These coils are divided into two groups. When these groups are connected such that their magnetomotive forces are additive, two pole motor operation results. When the polarity of one of the groups is then reversed, six pole motor operation results. An auxiliary stator winding which is similar to the main stator winding is displaced from the main stator winding by 90 electrical degrees on a two pole basis. 12 figs.

Limiting (zero-load) speed of the rotary motor of Escherichia coli is independent of the number of torque-generating units

PubMed Central

Wang, Bin; Zhang, Rongjing; Yuan, Junhua

2017-01-01

Rotation of the bacterial flagellar motor is driven by multiple torque-generating units (stator elements). The torque-generating dynamics can be understood in terms of the “duty ratio” of the stator elements, that is, the fraction of time a stator element engages with the rotor during its mechanochemical cycle. The dependence of the limiting speed (zero-load speed) of the motor on the number of stator elements is the determining test of the duty ratio, which has been controversial experimentally and theoretically over the past decade. Here, we developed a method combining laser dark-field microscopy and optical trapping to resolve this controversy. We found that the zero-load speed is independent of the number of stator elements for the bacterial flagellar motor in Escherichia coli, demonstrating that these elements have a duty ratio close to 1. PMID:29109285

Limiting (zero-load) speed of the rotary motor of Escherichia coli is independent of the number of torque-generating units.

PubMed

Wang, Bin; Zhang, Rongjing; Yuan, Junhua

2017-11-21

Rotation of the bacterial flagellar motor is driven by multiple torque-generating units (stator elements). The torque-generating dynamics can be understood in terms of the "duty ratio" of the stator elements, that is, the fraction of time a stator element engages with the rotor during its mechanochemical cycle. The dependence of the limiting speed (zero-load speed) of the motor on the number of stator elements is the determining test of the duty ratio, which has been controversial experimentally and theoretically over the past decade. Here, we developed a method combining laser dark-field microscopy and optical trapping to resolve this controversy. We found that the zero-load speed is independent of the number of stator elements for the bacterial flagellar motor in Escherichia coli , demonstrating that these elements have a duty ratio close to 1.

A finite element-based algorithm for rubbing induced vibration prediction in rotors

NASA Astrophysics Data System (ADS)

Behzad, Mehdi; Alvandi, Mehdi; Mba, David; Jamali, Jalil

2013-10-01

In this paper, an algorithm is developed for more realistic investigation of rotor-to-stator rubbing vibration, based on finite element theory with unilateral contact and friction conditions. To model the rotor, cross sections are assumed to be radially rigid. A finite element discretization based on traditional beam theories which sufficiently accounts for axial and transversal flexibility of the rotor is used. A general finite element discretization model considering inertial and viscoelastic characteristics of the stator is used for modeling the stator. Therefore, for contact analysis, only the boundary of the stator is discretized. The contact problem is defined as the contact between the circular rigid cross section of the rotor and “nodes” of the stator only. Next, Gap function and contact conditions are described for the contact problem. Two finite element models of the rotor and the stator are coupled via the Lagrange multipliers method in order to obtain the constrained equation of motion. A case study of the partial rubbing is simulated using the algorithm. The synchronous and subsynchronous responses of the partial rubbing are obtained for different rotational speeds. In addition, a sensitivity analysis is carried out with respect to the initial clearance, the stator stiffness, the damping parameter, and the coefficient of friction. There is a good agreement between the result of this research and the experimental result in the literature.

Ultrasonic Motors (USM) - an emerging actuation technology for planetary applications

NASA Technical Reports Server (NTRS)

Bao, X.; Das, H.

2000-01-01

A hybrid model that addressed a complete ultrasonic motor as a system was developed. The model allows using powerful commercial FE package to express dynamic characteristics of the stator and the rotor in engineering practice. An analog model couples the finite element models for the stator and rotor for the stator-interface layer-rotor syste. The model provides reasonably accurate results for CAD.

Split Coil Forms for Rotary Transformers

NASA Technical Reports Server (NTRS)

Mclyman, C. W. T.

1982-01-01

Split cores for rotor and stator windings of rotary transformer mounted around their respective coils (which are in bobbins) and cemented together. This arrangement simplifies winding of stator coil to go in a slot in inner diameter of stator coil. One practical application of rotary transformers fabricated according to this technique is for centrifuges, in which conventional sliprings are of uncertain reliability.

Parametric Blade Study Test Report Rotor Configuration. Number 2

DTIC Science & Technology

1988-11-01

Incidence Angle (100% N) .............. 51 9 Rotor Relative Inlet Mach Number (100% N) ... 51 1G Rotor Loss Coefficient (100% N) ............. 52 11 Rotor...Diffusion Factor (100% N) ............. 52 12 Rotor Deviation Angle (100% N) .............. 53 13 Stator Incidence Angle (100% N) ............. 53 14...78 50 Stator Deviation Angle (90% N) .............. 79 51 Stator Loss Coefficient (90% N) ............. 79 52 Static Pressure Distribution

Torres del Paine National Park

NASA Image and Video Library

2017-12-08

Grinding glaciers and granite peaks mingle in Chile’s Torres del Paine National Park. The Advanced Land Imager (ALI) on NASA’s Earth Observing-1 (EO-1) satellite captured this summertime image of the park on January 21, 2013. This image shows just a portion of the park, including Grey Glacier and the mountain range of Cordillera del Paine. The rivers of glacial ice in Torres del Paine National Park grind over bedrock, turning some of that rock to dust. Many of the glaciers terminate in freshwater lakes, which are rich with glacial flour that colors them brown to turquoise. Skinny rivers connect some of the lakes to each other (image upper and lower right). Cordillera del Paine rises between some of the wide glacial valleys. The compact mountain range is a combination of soaring peaks and small glaciers, most notably the Torres del Paine (Towers of Paine), three closely spaced peaks emblematic of the mountain range and the larger park. By human standards, the mountains of Cordillera del Paine are quite old. But compared to the Rocky Mountains (70 million years old), and the Appalachians (about 480 million years), the Cordillera del Paine are very young—only about 12 million years old. A study published in 2008 described how scientists used zircon crystals to estimate the age of Cordillera del Paine. The authors concluded that the mountain range was built in three pulses, creating a granite laccolith, or dome-shaped feature, more than 2,000 meters (7,000 feet) thick. NASA Earth Observatory image created by Jesse Allen and Robert Simmon, using Advanced Land Imager data from the NASA EO-1 team. Caption by Michon Scott. Instrument: EO-1 - ALI View more info: earthobservatory.nasa.gov/IOTD/view.php?id=80266 Credit: NASA Earth Observatory NASA image use policy. NASA Goddard Space Flight Center enables NASA’s mission through four scientific endeavors: Earth Science, Heliophysics, Solar System Exploration, and Astrophysics. Goddard plays a leading role in NASA�

Coupled 2-dimensional cascade theory for noise and unsteady aerodynamics of blade row interaction in turbofans. Volume 1: Theory development and parametric studies

NASA Technical Reports Server (NTRS)

Hanson, Donald B.

1994-01-01

Typical analytical models for interaction between rotor and stator in a turbofan analyze the effect of wakes from the rotor impinging on the stator, producing unsteady loading, and thereby generating noise. Reflection/transmission characteristics of the rotor are sometimes added in a separate calculation. In those models, there is a one-to-one relationship between wake harmonics and noise harmonics; that is, the BPF (blade passing frequency) wake harmonic causes only the BPF noise harmonic, etc. This report presents a more complete model in which flow tangency boundary conditions are satisfied on two cascades in relative motion for several harmonics simultaneously. By an extension of S.N. Smith's code for two dimensional flat plate cascades, the noise generation/frequency scattering/blade row reflection problem is solved in a single matrix inversion. It is found that the BPF harmonic excitation of the stator scatters considerable energy in the higher BPF harmonics due to relative motion between the blade rows. Furthermore, when swirl between the rotor and stator is modeled, a 'mode trapping' effect occurs which explains observations on fans operating at rotational speeds below BFP cuton: the BPF mode amplifies between blade rows by multiple reflections but cannot escape to the inlet and exit ducts. However, energy scattered into higher harmonics does propagate and dominates the spectrum at two and three times BPF. This report presents the complete derivation of the theory, comparison with a previous (more limited) coupled rotor/stator interaction theory due to Kaji and Okazaki, exploration of the mode trapping phenomenon, and parametric studies showing the effects of vane/blade ratio and rotor/stator interaction. For generality, the analysis applies to stages where the rotor is either upstream or downstream of the stator and to counter rotation stages. The theory has been coded in a FORTRAN program called CUP2D, documented in Volume 2 of this report. It is

Aerodynamic Evaluation of Two Compact Radial-Inflow Turbine Rotors

NASA Technical Reports Server (NTRS)

Simonyi, P. Susan; Roelke, Richard J.; Stabe, Roy G.; Nowlin, Brentley C.; Dicicco, Danielle

1995-01-01

The aerodynamic evaluation of two highly loaded compact radial turbine rotors was conducted at the NASA Lewis Research Center Small Engine Component Test Facility (SECTF). The experimental results were used for proof-of-concept, for modeling radial inflow turbine rotors, and for providing data for code verification. Two rotors were designed to have a shorter axial length, up to a 10-percent reduced diameter, a lighter weight, and equal or higher efficiencies with those of conventional radial inflow turbine rotors. Three configurations were tested: rotor 1, having a 40-percent shorter axial length, with the design stator (stator 1); rotor 1 with the design stator vanes closed down (stator 2); and rotor 2, slightly shorter axially and having higher loading, with stator 2. The stator had 36 vanes and the rotors each had 14 solid blades. Although presently uncooled, the rotor blades were designed for thicknesses which would allow cooling passages to be added. The overall stage performance measurements and the rotor and stator exit flow field surveys were obtained. Measurements of steady state temperatures, pressures, mass flow rates, flow angles, and output power were made at various operating conditions. Data were obtained at corrected speeds of 80, 90, 100, 110, and 120 percent of design over a range of equivalent inlet-to-exit pressure ratios of 3.5, 4.0, 4.5, and 5.0, the maximum pressure ratio achieved. The test showed that the configuration of rotor 1 with stator 1 running at the design pressure ratio produced a flow rate which was 5.6 percent higher than expected. This result indicated the need to close down the stator flow area to reduce the flow. The flow area reduction was accomplished by restaggering the vanes. Rotor 1 was retested with the closed-down stator vanes and achieved the correct mass flow. Rotor 2 was tested only with the restaggered vanes. The test results of the three turbine configurations were nearly identical. Although the measured

Design of a Low Speed Fan Stage for Noise Suppression

NASA Technical Reports Server (NTRS)

Dalton, W. N.; Elliot, D. B.; Nickols, K. L.

1999-01-01

This report describes the design of a low tip speed, moderate pressure rise fan stage for demonstration of noise reduction concepts. The fan rotor is a fixed-pitch configuration delivering a design pressure ratio of 1.378 at a specific flow of 43.1 lbm/sec/sq ft. Four exit stator configurations were provided to demonstrate the effectiveness of circumferential and axial sweep in reducing rotor-stator interaction tone noise. The fan stage design was combined with an axisymmetric inlet, conical convergent nozzle, and nacelle to form a powered fan-nacelle subscale model. This model has a 22-inch cylindrical flow path and employs a rotor with a 0.30 hub-to-tip radius ratio. The design is fully compatible with an existing NASA force balance and rig drive system. The stage aerodynamic and structural design is described in detail. Three-dimensional (3-D) computational fluid dynamics (CFD) tools were used to define optimum airfoil sections for both the rotor and stators. A fan noise predictive system developed by Pratt & Whitney under contract to NASA was used to determine the acoustic characteristics of the various stator configurations. Parameters varied included rotor-to-stator spacing and vane leading edge sweep. The structural analysis of the rotor and stator are described herein. An integral blade and disk configuration was selected for the rotor. Analysis confirmed adequate low cycle fatigue life, vibratory endurance strength, and aeroelastic suitability. A unique load carrying stator arrangement was selected to minimize generation of tonal noise due to sources other than rotor-stator interaction. Analysis of all static structural components demonstrated adequate strength, fatigue life, and vibratory characteristics.

Mechanics of torque generation in the bacterial flagellar motor

PubMed Central

Mandadapu, Kranthi K.; Nirody, Jasmine A.; Berry, Richard M.; Oster, George

2015-01-01

The bacterial flagellar motor (BFM) is responsible for driving bacterial locomotion and chemotaxis, fundamental processes in pathogenesis and biofilm formation. In the BFM, torque is generated at the interface between transmembrane proteins (stators) and a rotor. It is well established that the passage of ions down a transmembrane gradient through the stator complex provides the energy for torque generation. However, the physics involved in this energy conversion remain poorly understood. Here we propose a mechanically specific model for torque generation in the BFM. In particular, we identify roles for two fundamental forces involved in torque generation: electrostatic and steric. We propose that electrostatic forces serve to position the stator, whereas steric forces comprise the actual “power stroke.” Specifically, we propose that ion-induced conformational changes about a proline “hinge” residue in a stator α-helix are directly responsible for generating the power stroke. Our model predictions fit well with recent experiments on a single-stator motor. The proposed model provides a mechanical explanation for several fundamental properties of the flagellar motor, including torque–speed and speed–ion motive force relationships, backstepping, variation in step sizes, and the effects of key mutations in the stator. PMID:26216959

Mechanics of torque generation in the bacterial flagellar motor.

PubMed

Mandadapu, Kranthi K; Nirody, Jasmine A; Berry, Richard M; Oster, George

2015-08-11

The bacterial flagellar motor (BFM) is responsible for driving bacterial locomotion and chemotaxis, fundamental processes in pathogenesis and biofilm formation. In the BFM, torque is generated at the interface between transmembrane proteins (stators) and a rotor. It is well established that the passage of ions down a transmembrane gradient through the stator complex provides the energy for torque generation. However, the physics involved in this energy conversion remain poorly understood. Here we propose a mechanically specific model for torque generation in the BFM. In particular, we identify roles for two fundamental forces involved in torque generation: electrostatic and steric. We propose that electrostatic forces serve to position the stator, whereas steric forces comprise the actual "power stroke." Specifically, we propose that ion-induced conformational changes about a proline "hinge" residue in a stator α-helix are directly responsible for generating the power stroke. Our model predictions fit well with recent experiments on a single-stator motor. The proposed model provides a mechanical explanation for several fundamental properties of the flagellar motor, including torque-speed and speed-ion motive force relationships, backstepping, variation in step sizes, and the effects of key mutations in the stator.

Tezacaftor/Ivacaftor in Subjects with Cystic Fibrosis and F508del/F508del-CFTR or F508del/G551D-CFTR.

PubMed

Donaldson, Scott H; Pilewski, Joseph M; Griese, Matthias; Cooke, Jon; Viswanathan, Lakshmi; Tullis, Elizabeth; Davies, Jane C; Lekstrom-Himes, Julie A; Wang, Linda T

2018-01-15

Tezacaftor (formerly VX-661) is an investigational small molecule that improves processing and trafficking of the cystic fibrosis transmembrane conductance regulator (CFTR) in vitro, and improves CFTR function alone and in combination with ivacaftor. To evaluate the safety and efficacy of tezacaftor monotherapy and of tezacaftor/ivacaftor combination therapy in subjects with cystic fibrosis homozygous for F508del or compound heterozygous for F508del and G551D. This was a randomized, placebo-controlled, double-blind, multicenter, phase 2 study (NCT01531673). Subjects homozygous for F508del received tezacaftor (10 to 150 mg) every day alone or in combination with ivacaftor (150 mg every 12 h) in a dose escalation phase, as well as in a dosage regimen testing phase. Subjects compound heterozygous for F508del and G551D, taking physician-prescribed ivacaftor, received tezacaftor (100 mg every day). Primary endpoints were safety through Day 56 and change in sweat chloride from baseline through Day 28. Secondary endpoints included change in percent predicted FEV 1 (ppFEV 1 ) from baseline through Day 28 and pharmacokinetics. The incidence of adverse events was similar across treatment arms. Tezacaftor (100 mg every day)/ivacaftor (150 mg every 12 h) resulted in a 6.04 mmol/L decrease in sweat chloride and 3.75 percentage point increase in ppFEV 1 in subjects homozygous for F508del, and a 7.02 mmol/L decrease in sweat chloride and 4.60 percentage point increase in ppFEV 1 in subjects compound heterozygous for F508del and G551D from baseline through Day 28 (P < 0.05 for all). These results support continued clinical development of tezacaftor (100 mg every day) in combination with ivacaftor (150 mg every 12 h) in subjects with cystic fibrosis. Clinical trial registered with www.clinicaltrials.gov (NCT01531673).

Submersible sodium pump

DOEpatents

Brynsvold, Glen V.; Lopez, John T.; Olich, Eugene E.; West, Calvin W.

1989-01-01

An electromagnetic submerged pump has an outer cylindrical stator with an inner cylindrical conductive core for the submerged pumping of sodium in the cylindrical interstitial volume defined between the stator and core. The cylindrical interstitial volume is typically vertically oriented, and defines an inlet at the bottom and an outlet at the top. The outer stator generates upwardly conveyed toroidal magnetic fields, which fields convey preferably from the bottom of the pump to the top of the pump liquid sodium in the cold leg of a sodium cooled nuclear reactor. The outer cylindrical stator has a vertically disposed duct surrounded by alternately stacked layers of coil units and laminates.

Submersible sodium pump

DOEpatents

Brynsvold, G.V.; Lopez, J.T.; Olich, E.E.; West, C.W.

1989-11-21

An electromagnetic submerged pump has an outer cylindrical stator with an inner cylindrical conductive core for the submerged pumping of sodium in the cylindrical interstitial volume defined between the stator and core. The cylindrical interstitial volume is typically vertically oriented, and defines an inlet at the bottom and an outlet at the top. The outer stator generates upwardly conveyed toroidal magnetic fields, which fields convey preferably from the bottom of the pump to the top of the pump liquid sodium in the cold leg of a sodium cooled nuclear reactor. The outer cylindrical stator has a vertically disposed duct surrounded by alternately stacked layers of coil units and laminates. 14 figs.

Kurt Gödels Brünner Verwandte

NASA Astrophysics Data System (ADS)

Müller, Dora

2007-11-01

The author of this memoir Dora Müller (born 1920) belongs - as well as Kurt Gödel-to the German minority playing an important role in the past life of Brno. The marriage of his son included her among the Gödels collaterals. She was chemist, but also pianist, historician, participant of antinacist movement and iniciator of Czech-German understanding after war. Following her personal experiences, remembrances of Gödels relatives and documental materials, she evokes the atmosphere of broader family milieu of Kurt Gödel.

The novel c.247_249delTTC (p.F83del) GJB2 mutation in a family with prelingual sensorineural deafness.

PubMed

Petersen, Michael B; Grigoriadou, Maria; Koutroumpe, Maria; Kokotas, Haris

2012-07-01

Non-syndromic hearing loss is one of the most common hereditary determined diseases in human, and the disease is a genetically heterogeneous disorder. Mutations in the GJB2 gene, encoding connexin 26 (Cx26), are a major cause of non-syndromic recessive hearing impairment in many countries and are largely dependent on ethnic groups. Due to the high frequency of the c.35delG GJB2 mutation in the Greek population, we have previously suggested that Greek patients with sensorineural, non-syndromic deafness should be tested for the c.35delG mutation and the coding region of the GJB2 gene should be sequenced in c.35delG heterozygotes. Here we present on the clinical and molecular genetic evaluation of a family suffering from prelingual, sensorineural, non-syndromic deafness. A novel c.247_249delTTC (p.F83del) GJB2 mutation was detected in compound heterozygosity with the c.35delG GJB2 mutation in the proband and was later confirmed in the father, while the mother was homozygous for the c.35delG GJB2 mutation. We conclude that compound heterozygosity of the novel c.247_249delTTC (p.F83del) and the c.35delG mutations in the GJB2 gene was the cause of deafness in the proband and his father. Copyright © 2012 Elsevier Ireland Ltd. All rights reserved.

Unsteady Flow Field in a Multistage Axial Flow Compressor

NASA Technical Reports Server (NTRS)

Suryavamshi, N.; Lakshminarayana, B.; Prato, J.

1997-01-01

The flow field in a multistage compressor is three-dimensional, unsteady, and turbulent with substantial viscous effects. Some of the specific phenomena that has eluded designers include the effects of rotor-stator and rotor-rotor interactions and the physics of mixing of velocity, pressure, temperature and velocity fields. An attempt was made, to resolve experimentally, the unsteady pressure and temperature fields downstream of the second stator of a multistage axial flow compressor which will provide information on rotor-stator interaction effects and the nature of the unsteadiness in an embedded stator of a three stage axial flow compressor. Detailed area traverse measurements using pneumatic five hole probe, thermocouple probe, semi-conductor total pressure probe (Kulite) and an aspirating probe downstream of the second stator were conducted at the peak efficiency operating condition. The unsteady data was then reduced through an ensemble averaging technique which splits the signal into deterministic and unresolved components. Auto and cross correlation techniques were used to correlate the deterministic total temperature and velocity components (acquired using a slanted hot-film probe at the same measurement locations) and the gradients, distributions and relative weights of each of the terms of the average passage equation were then determined. Based on these measurements it was observed that the stator wakes, hub leakage flow region, casing endwall suction surface corner region, and the casing endwall region away from the blade surfaces were the regions of highest losses in total pressure, lowest efficiency and highest levels of unresolved unsteadiness. The deterministic unsteadiness was found to be high in the hub and casing endwall regions as well as on the pressure side of the stator wake. The spectral distribution of hot-wire and kulite voltages shows that at least eight harmonics of all three rotor blade passing frequencies are present at this

Surface Temperature Measurements from a Stator Vane Doublet in a Turbine Engine Afterburner Flame using Ultra-Bright Cr-Doped GdAlO3 Thermographic Phosphor

NASA Technical Reports Server (NTRS)

Eldridge, Jeffrey I.; Jenkins, Thomas P.; Allison, Stephen W.; Wolfe, Douglas E.; Howard, Robert P.

2013-01-01

Luminescence-based surface temperature measurements from an ultra-bright Cr-doped GdAlO3 perovskite (GAP:Cr) coating were successfully conducted on an air-film-cooled stator vane doublet exposed to the afterburner flame of a J85 test engine at University of Tennessee Space Institute (UTSI). The objective of the testing at UTSI was to demonstrate that reliable thermal barrier coating (TBC) surface temperatures based on luminescence decay of a thermographic phosphor could be obtained from the surface of an actual engine component in an aggressive afterburner flame environment and to address the challenges of a highly radiant background and high velocity gases. A high-pressure turbine vane doublet from a Honeywell TECH7000 turbine engine was coated with a standard electron-beam physical vapor deposited (EB-PVD) 200-m-thick TBC composed of yttria-stabilized zirconia (YSZ) onto which a 25-m-thick GAP:Cr thermographic phosphor layer was deposited by EB-PVD. The ultra-bright broadband luminescence from the GAP:Cr thermographic phosphor is shown to offer the advantage of over an order-of-magnitude greater emission intensity compared to rare-earth-doped phosphors in the engine test environment. This higher emission intensity was shown to be very desirable for overcoming the necessarily restricted probe light collection solid angle and for achieving high signal-to-background levels. Luminescence-decay-based surface temperature measurements varied from 500 to over 1000C depending on engine operating conditions and level of air film cooling.

Estudio del CH interestelar

NASA Astrophysics Data System (ADS)

Olano, C.; Lemarchand, G.; Sanz, A. J.; Bava, J. A.

El objetivo principal de este proyecto consiste en el estudio de la distribución y abundancia del CH en nubes interestelares a través de la observación de las líneas hiperfinas del CH en 3,3 GHz. El CH es una molécula de amplia distribución en el espacio interestelar y una de las pocas especies que han sido observadas tanto con técnicas de radio como ópticas. Desde el punto de vista tecnológico se ha desarrollado un cabezal de receptor que permitirá la realización de observaciones polarimétricas en la frecuencia de 3,3 GHz, con una temperatura del sistema de 60 K y un ancho de banda de 140 MHz, y que será instalado en el foco primario de la antena parabólica del IAR. El cabezal del receptor es capaz de detectar señales polarizadas, separando las componentes de polarización circular derecha e izquierda. Para tal fin el cabezal consta de dos ramas receptoras que amplificarán la señal y la trasladarán a una frecuencia más baja (frecuencia intermedia), permitiendo de esa forma un mejor transporte de la señal a la sala de control para su posterior procesamiento. El receptor además de tener características polarimétricas, podrá ser usado en el continuo y en la línea, utilizando las ventajas observacionales y de procesamiento de señal que actualmente posee el IAR.

Estimation of the iron loss in deep-sea permanent magnet motors considering seawater compressive stress.

PubMed

Xu, Yongxiang; Wei, Yanyu; Zou, Jibin; Li, Jianjun; Qi, Wenjuan; Li, Yong

2014-01-01

Deep-sea permanent magnet motor equipped with fluid compensated pressure-tolerant system is compressed by the high pressure fluid both outside and inside. The induced stress distribution in stator core is significantly different from that in land type motor. Its effect on the magnetic properties of stator core is important for deep-sea motor designers but seldom reported. In this paper, the stress distribution in stator core, regarding the seawater compressive stress, is calculated by 2D finite element method (FEM). The effect of compressive stress on magnetic properties of electrical steel sheet, that is, permeability, BH curves, and BW curves, is also measured. Then, based on the measured magnetic properties and calculated stress distribution, the stator iron loss is estimated by stress-electromagnetics-coupling FEM. At last the estimation is verified by experiment. Both the calculated and measured results show that stator iron loss increases obviously with the seawater compressive stress.

Estimation of the Iron Loss in Deep-Sea Permanent Magnet Motors considering Seawater Compressive Stress

PubMed Central

Wei, Yanyu; Zou, Jibin; Li, Jianjun; Qi, Wenjuan; Li, Yong

2014-01-01

Deep-sea permanent magnet motor equipped with fluid compensated pressure-tolerant system is compressed by the high pressure fluid both outside and inside. The induced stress distribution in stator core is significantly different from that in land type motor. Its effect on the magnetic properties of stator core is important for deep-sea motor designers but seldom reported. In this paper, the stress distribution in stator core, regarding the seawater compressive stress, is calculated by 2D finite element method (FEM). The effect of compressive stress on magnetic properties of electrical steel sheet, that is, permeability, BH curves, and BW curves, is also measured. Then, based on the measured magnetic properties and calculated stress distribution, the stator iron loss is estimated by stress-electromagnetics-coupling FEM. At last the estimation is verified by experiment. Both the calculated and measured results show that stator iron loss increases obviously with the seawater compressive stress. PMID:25177717

Design and performance testing of an ultrasonic linear motor with dual piezoelectric actuators.

PubMed

Smithmaitrie, Pruittikorn; Suybangdum, Panumas; Laoratanakul, Pitak; Muensit, Nantakan

2012-05-01

In this work, design and performance testing of an ultrasonic linear motor with dual piezoelectric actuator patches are studied. The motor system consists of a linear stator, a pre-load weight, and two piezoelectric actuator patches. The piezoelectric actuators are bonded with the linear elastic stator at specific locations. The stator generates propagating waves when the piezoelectric actuators are subjected to harmonic excitations. Vibration characteristics of the linear stator are analyzed and compared with finite element and experimental results. The analytical, finite element, and experimental results show agreement. In the experiments, performance of the ultrasonic linear motor is tested. Relationships between velocity and pre-load weight, velocity and applied voltage, driving force and applied voltage, and velocity and driving force are reported. The design of the dual piezoelectric actuators yields a simpler structure with a smaller number of actuators and lower stator stiffness compared with a conventional design of an ultrasonic linear motor with fully laminated piezoelectric actuators.

Características del viento en estrellas Be derivadas del perfil Hα

NASA Astrophysics Data System (ADS)

Rohrmann, R.; Cidale, L.

El estudio teórico de perfiles Hα y su variabilidad en estrellas Be ha sido frecuentemente desarrollado en base a modelos de envolturas circunestelares inhomogéneas, donde la geometría del material es responsable de la forma del perfil dependiendo de la dirección de observación. Nosotros damos una interpretación alternativa y proponemos que la mayoría de las propiedades de esta línea tienen origen en la base de un viento estelar y de una estructura cromosférica anexa a la fotósfera. Encontramos que típicos perfiles Hα en Be, como son los llamados pole-on y winebottle, pueden ser reproducidos cualitativamente sin recurrir a la existencia de una envoltura asimétrica. Analizamos como la línea Hα permite identificar la posible estructura del viento en la región donde éste se inicia.

Tierra del Fuego, Argentina, South America

NASA Technical Reports Server (NTRS)

1991-01-01

The Mitre Peninsula is the easternmost tip of Tierra del Fuego, Argentina, (54.5S, 65.5W). Early winter snow can be seen on this south tip of the Andes Mountains. These same mountains continue underwater to Antarctica. The Strait of Magellan, separating the South American mainland from Tierra del Fuego is off the scene to the north and west, but the Strait of LeMaire, separating Tierra del Fuego from the Isla de los Estados can be seen.

High pressure superconducting radial magnetic bearing

NASA Technical Reports Server (NTRS)

Eyssa, Y. M.; Huang, X.

1990-01-01

In a conventional radial magnetic bearing, the rotor (soft magnetic material) can only have attraction force from one of the electromagnets in the stator. The stator electromagnets consist of small copper windings with a soft magnetic material iron yoke. The maximum pressure obtainable is about 200 N/sq cm. It is shown that replacing the stator copper winding by a superconducting winding in the above configuration can increase the pressure to about 1000 N/sq cm. It is also shown that replacing the iron in the rotor by a group of superconducting windings in persistent mode and using a group of saddle coils in the stator can produce a pressure in excess of 2000 N/sq cm.

Substantially parallel flux uncluttered rotor machines

DOEpatents

Hsu, John S.

2012-12-11

A permanent magnet-less and brushless synchronous system includes a stator that generates a magnetic rotating field when sourced by polyphase alternating currents. An uncluttered rotor is positioned within the magnetic rotating field and is spaced apart from the stator. An excitation core is spaced apart from the stator and the uncluttered rotor and magnetically couples the uncluttered rotor. The brushless excitation source generates a magnet torque by inducing magnetic poles near an outer peripheral surface of the uncluttered rotor, and the stator currents also generate a reluctance torque by a reaction of the difference between the direct and quadrature magnetic paths of the uncluttered rotor. The system can be used either as a motor or a generator

Unidades del paisaje de Puerto Rico: la influencia del clima, el substrato y la topografia

Treesearch

William Gould; Michael E. Jimenez; Gary Potts; Maya Quinones; Sebastian Martinuzzi

2008-01-01

El mapa de unidades del paisaje de Puerto Rico representa variaciones climaticas, topograficas y del substrato mediante la integracion de seis zonas climaticas (Ewel y Whitmore, 1973), seis substratos (Bawiec, 2001; USGS, 2005), cinco posiciones topograficas, o topoformas (Martinuzzi et al. 2007), y cuerpos de agua (USGS 2005). Los substratos representan el conjunto...

Characteristics of a multilayer one-touch-point ultrasonic motor for high torque

NASA Astrophysics Data System (ADS)

Jeong, Seong-Su; Park, Tae-Gone; Park, Jong-Kyu

2013-04-01

In this paper, a one-touch-point ultrasonic motor is proposed. Fabricating the stator is easy because of its simple structure and the use of a punching technique. Also, a thin stator is advantageous to use in tight spaces. A thin metal plate was used as a V-shaped stator and two to the upper and two to the lower ceramic plates were attached to the upper and the lower surfaces respectively of the metal plate. When two sinusoidal sources with a phase difference of 90 degrees were applied to the stator, an elliptical displacement was generated at contact tip of the stator. Modeling of the ultrasonic motor was done and the displacement characteristics were defined by using a finite element analysis program (ATILA). To improve the speed and the torque of the ultrasonic motor, we analyzed the effects of the leg angle and the number of ceramic layers. In addition, a model with large x-axis and y-axis displacements was fabricated, and the speed and the torque were measured under various conditions. The elliptical motion of the contact tip of the stator was consistently obtained at the resonance frequency. The maximum speed and torque were obtained by using maximum elliptical displacement model. The speed and the torque increased linearly with increasing voltage.

Source Methodology for Turbofan Noise Prediction (SOURCE3D Technical Documentation)

NASA Technical Reports Server (NTRS)

Meyer, Harold D.

1999-01-01

This report provides the analytical documentation for the SOURCE3D Rotor Wake/Stator Interaction Code. It derives the equations for the rotor scattering coefficients and stator source vector and scattering coefficients that are needed for use in the TFANS (Theoretical Fan Noise Design/Prediction System). SOURCE3D treats the rotor and stator as isolated source elements. TFANS uses this information, along with scattering coefficients for inlet and exit elements, and provides complete noise solutions for turbofan engines. SOURCE3D is composed of a collection of FORTRAN programs that have been obtained by extending the approach of the earlier V072 Rotor Wake/Stator Interaction Code. Similar to V072, it treats the rotor and stator as a collection of blades and vanes having zero thickness and camber contained in an infinite, hardwall annular duct. SOURCE3D adds important features to the V072 capability-a rotor element, swirl flow and vorticity waves, actuator disks for flow turning, and combined rotor/actuator disk and stator/actuator disk elements. These items allow reflections from the rotor, frequency scattering, and mode trapping, thus providing more complete noise predictions than previously. The code has been thoroughly verified through comparison with D.B. Hanson's CUP2D two- dimensional code using a narrow annulus test case.

Reluctance apparatus for flywheel energy storage

DOEpatents

Hull, John R.

2000-01-01

A motor generator for providing high efficiency, controlled voltage output or storage of energy in a flywheel system. A motor generator includes a stator of a soft ferromagnetic material, a motor coil and a generator coil, and a rotor has at least one embedded soft ferromagnetic piece. Control of voltage output is achieved by use of multiple stator pieces and multiple rotors with controllable gaps between the stator pieces and the soft ferromagnetic piece.

Hermetically sealed superconducting magnet motor

DOEpatents

DeVault, Robert C.; McConnell, Benjamin W.; Phillips, Benjamin A.

1996-01-01

A hermetically sealed superconducting magnet motor includes a rotor separated from a stator by either a radial gap, an axial gap, or a combined axial and radial gap. Dual conically shaped stators are used in one embodiment to levitate a disc-shaped rotor made of superconducting material within a conduit for moving cryogenic fluid. As the rotor is caused to rotate when the field stator is energized, the fluid is pumped through the conduit.

Analisis del contenido curricular de los Documentos Normativos del Programa de Ciencias en el area de biologia para la escuela superior del sistema de educacion publica de Puerto Rico: 1993-2012

NASA Astrophysics Data System (ADS)

Davila Montanez, Melissa

Esta investigacion de naturaleza cualitativa se ocupo de realizar un analisis de contenido documental de los Documentos Normativos del Programa de Ciencias en el area de biologia de la escuela superior del sistema de educacion publica de Puerto Rico del periodo 1993-2012. Los documentos analizados fueron: Guia Curricular, 1995; Marco Curricular, 2003; Estandares de Excelencia, 1996, 2000 y Estandares de Contenido y Expectativas de Grado, 2007. Se indago si hubo cambios en significados en los Componentes Estructurales: Naturaleza de la ciencia, Paradigmas para la ensenanza de la ciencia, Funcion del curriculo formal, Mision de la ensenanza de la ciencia; Contenidos, destrezas y competencias, Estrategias de ensenanza y Evaluacion/Assessment del aprendizaje. El analisis sugiere que no hubo cambios sustanciales en los significados de los Componentes Estructurales. Los documentos estudiados muestran mayormente caracteristicas similares, aunque los documentos mas recientes eran mas descriptivos, explicativos y especificos.

Microgrid Restraining Strategy Based on Improved DC Grid Connected DFIG Torque Ripple

NASA Astrophysics Data System (ADS)

Fei, Xia; Yang, Zhixiong; Zongze, Xia

2017-05-01

Aiming to the voltage of the stator side is generated by the modulation of the SSC in the improved topology, especially under the circumstance with the asymmTeric fault of stator side, DFIG’s electromagnTeic torque, amplifies ripple of grid-connected power for the grid side. The novel control mTehod suitable to stator side converter and rotor side converter based on reduced-order resonant controller (RORC) is proposed in this thesis, DFIG’s torque and output power performance are improved. Under the RORC control conditions the transfer functions of stator current and torque control system are established, the amplitude characteristic and the system stability of RORC control are analysed. The simulation results in Matlab/Simulink verify the correctness and validity of the proposed mTehod.

Forward and reverse control system for induction motors

DOEpatents

Wright, J.T.

1987-09-15

A control system for controlling the direction of rotation of a rotor of an induction motor includes an array of five triacs with one of the triacs applying a current of fixed phase to the windings of the rotor and four of the triacs being switchable to apply either hot ac current or return ac current to the stator windings so as to reverse the phase of current in the stator relative to that of the rotor and thereby reverse the direction of rotation of the rotor. Switching current phase in the stator is accomplished by operating the gates of pairs of the triacs so as to connect either hot ac current or return ac current to the input winding of the stator. 1 fig.

Highly loaded multi-stage fan drive turbine - performance of initial seven configurations

NASA Technical Reports Server (NTRS)

Wolfmeyer, G. W.; Thomas, M. W.

1974-01-01

Experimental results of a three-stage highly loaded fan drive turbine test program are presented. A plain blade turbine, a tandem blade turbine, and a tangentially leaned stator turbine were designed for the same velocity diagram and flowpath. Seven combinations of bladerows were tested to evaluate stage performances and effects of the tandem blading and leaned stator. The plain blade turbine design point total-to-total efficiency was 0.886. The turbine with the stage three leaned stator had the same efficiency with an improved exit swirl profile and increased hub reaction. Two-stage group tests showed that the two-stage turbine with tandem stage two stator had an efficiency of 0.880 compared to 0.868 for the plain blade two-stage turbine.

Estudio teórico del CO2. Orbitales de valencia y del ``core''

NASA Astrophysics Data System (ADS)

Olalla Gutiérrez, E.

Hemos calculado las intensidades de las transiciones E1 a los miembros de las series de Rydberg con origen en los orbitales ``no enlazantes'' del dióxido de carbono, especie de conocida relevancia atmosférica. Se han computado, asimismo, los continuos de fotoionización correspondientes a los distintos canales de ionización, representándolos como densidad espectral de fuerza de oscilador frente a la energía del fotón incidente; mostramos los resultados df/dE para la fotoionización total de esta especie en el intervalo 15-60 eV. Todos los cálculos se han llevado a cabo mediante la formulación Molecular del Método de los Orbitales de Defecto Cuántico, MQDO [1,2]. La calidad de los resultados que presentamos se ha evaluado en base a la comparación con los datos, tanto experimentales como teóricos, disponibles en la bibliografía. El acuerdo encontrado es altamente satisfactorio

Method and apparatus for rapid thrust increases in a turbofan engine

NASA Technical Reports Server (NTRS)

Cornett, J. E.; Corley, R. C.; Fraley, T. O.; Saunders, A. A., Jr. (Inventor)

1980-01-01

Upon a landing approach, the normal compressor stator schedule of a fan speed controlled turbofan engine is temporarily varied to substantially close the stators to thereby increase the fuel flow and compressor speed in order to maintain fan speed and thrust. This running of the compressor at an off-design speed substantially reduces the time required to subsequently advance the engine speed to the takeoff thrust level by advancing the throttle and opening the compressor stators.

Hermetically sealed superconducting magnet motor

DOEpatents

DeVault, R.C.; McConnell, B.W.; Phillips, B.A.

1996-07-02

A hermetically sealed superconducting magnet motor includes a rotor separated from a stator by either a radial gap, an axial gap, or a combined axial and radial gap. Dual conically shaped stators are used in one embodiment to levitate a disc-shaped rotor made of superconducting material within a conduit for moving cryogenic fluid. As the rotor is caused to rotate when the field stator is energized, the fluid is pumped through the conduit. 6 figs.

Passive control of discrete-frequency tones generated by coupled detuned cascades

NASA Astrophysics Data System (ADS)

Sawyer, S.; Fleeter, S.

2003-07-01

Discrete-frequency tones generated by rotor-stator interactions are of particular concern in the design of fans and compressors. Classical theory considers an isolated flat-plate cascade of identical uniformly spaced airfoils. The current analysis extends this tuned isolated cascade theory to consider coupled aerodynamically detuned cascades where aerodynamic detuning is accomplished by changing the chord of alternate rotor blades and stator vanes. In a coupled cascade analysis, the configuration of the rotor influences the downstream acoustic response of the stator, and the stator configuration influences the upstream acoustic response of the rotor. This coupled detuned cascade unsteady aerodynamic model is first applied to a baseline tuned stage. This baseline stage is then aerodynamically detuned by replacing alternate rotor blades and stator vanes with decreased chord airfoils. The nominal aerodynamically detuned stage configuration is then optimized, with the stage acoustic response decreased 13 dB upstream and 1 dB downstream at the design operating condition. A reduction in the acoustic response of the optimized aerodynamically detuned stage is then demonstrated over a range of operating conditions.

Blood Pump Having a Magnetically Suspended Rotor

NASA Technical Reports Server (NTRS)

Antaki, James F. (Inventor); Paden, Bradley (Inventor); Burgreen, Gregory (Inventor); Groom, Nelson J. (Inventor)

2002-01-01

A blood pump preferably has a magnetically suspended rotor that rotates within a housing. The rotor may rotate about a stator disposed within the housing. Radial magnetic bearings may be defined within the stator and the rotor in order to suspend the rotor. The radial magnetic bearings may be passive magnetic bearings that include permanent magnets disposed within the stator and the rotor or active magnetic bearings. The pump may further include an axial magnetic bearing that may be either a passive or an active magnetic bearing. A motor that drives the rotor may be disposed within the housing in order to more easily dissipate heat generated by the motor. A primary flow path is defined between the rotor and the stator, and a secondary flow path is defined between the stator and the rotor. Preferably, a substantial majority of blood passes through the primary flow path. The secondary flow path is large enough so that it provides adequate flushing of the secondary flow path while being small enough to permit efficient operation of the radial magnet bearings across the secondary flow path.

Effect of a rotor wake on heat transfer from a circular cylinder

NASA Technical Reports Server (NTRS)

Simoneau, R. J.; Morehouse, K. A.; Vanfossen, G. J.; Behning, F. P.

1984-01-01

The effect of a rotor wake on heat transfer to a downstream stator was investigated. The rotor was modeled with a spoked wheel of 24 circular pins 1.59 mm in diameter. One of the stator pins was electrically heated in the midspan region and circumferentially averaged heat transfer coefficients were obtained. The experiment was run in an annular flow wind tunnel using air at ambient temperature and pressure. Reynolds numbers based on stator cylinder diameter ranged from .001 to .00001. Rotor blade passing frequencies ranged from zero to 2500 Hz. Stationary grids were used to vary the rotor inlet turbulence from one to four percent. The rotor-stator spacings were one and two stator pin diameters. In addition to the heat transfer coefficients, turbulence spectra and ensemble averaged wake profiles were measured. At the higher Reynolds numbers, which is the primary range of interest for turbulent heat transfer, the rotor wakes increased Nusselt number from 10 to 45 percent depending on conditions. At lower Reynolds numbers the effect was as much as a factor of two.

Blood Pump Having a Magnetically Suspended Rotor

NASA Technical Reports Server (NTRS)

Antaki, James F. (Inventor); Paden, Bradley (Inventor); Burgreen, Gregory (Inventor); Groom, Nelson J. (Inventor)

2001-01-01

A blood pump preferably has a magnetically suspended rotor that rotates within a housing. The rotor may rotate about a stator disposed within the housing. Radial magnetic bearings may be defined within the stator and the rotor in order to suspend the rotor. The radial magnetic bearings may be passive magnetic bearings that include permanent magnets disposed within the stator and the rotor or active magnetic bearings. The pump may further include an axial magnetic bearing that may be either a passive or an active magnetic bearing. A motor that drives the rotor may be disposed within the housing in order to more easily dissipate heat generated by the motor. A primary flow path is defined between the rotor and the stator, and a secondary flow path is defined between the stator and the rotor. Preferably, a substantial majority of blood passes through the primary flow path. The secondary flow path is large enough so that it provides adequate flushing of the secondary flow path while being small enough to permit efficient operation of the radial magnet bearings across the secondary flow path.

Magnetic positioner having a single moving part

DOEpatents

Trumper, David L.; Kim, Won-Jong

1999-01-01

A magnetic positioner is provided which is capable of providing long travel in two dimension and short travel in the remaining four dimensions. The positioner has a movable stage and a stator oriented adjacent and substantially parallel to this stage. At least three sets of first magnetic elements, which for preferred embodiments are winding sets capable of generating forces in two directions, are on the portion of the stator adjacent to the stage at any given time, and at least two second magnetic elements, which are magnet arrays for the preferred embodiment, are on the stage adjacent to the stator. At least one of the second magnetic elements overlaps multiple first magnetic elements for all positions of the stage relative to the stator, with one magnet overlapping multiple windings for one preferred embodiment of the invention and two magnets on the stage overlapping multiple windings on the stator for a second embodiment. The windings form a linear motor providing forces in both a corresponding long travel dimension and in a dimension perpendicular to both long travel dimensions.

Sample processor for chemical analysis

NASA Technical Reports Server (NTRS)

Boettger, Heinz G. (Inventor)

1980-01-01

An apparatus is provided which can process numerous samples that must be chemically analyzed by the application of fluids such as liquid reagents, solvents and purge gases, as well as the application of dumps for receiving the applied fluid after they pass across the sample, in a manner that permits numerous samples to be processed in a relatively short time and with minimal manpower. The processor includes a rotor which can hold numerous cartridges containing inert or adsorbent material for holding samples, and a pair of stators on opposite sides of the rotor. The stators form stations spaced along the path of the cartridges which lie in the rotor, and each station can include an aperture in one stator through which a fluid can be applied to a cartridge resting at that station, and an aperture in the other stator which can receive the fluid which has passed through the cartridge. The stators are sealed to the ends of the cartridges lying on the rotor, to thereby isolate the stations from one another.

Fail safe controllable output improved version of the Electromechanical battery

DOEpatents

Post, Richard F.

1999-01-01

Mechanical means are provided to control the voltages induced in the windings of a generator/motor. In one embodiment, a lever is used to withdraw or insert the entire stator windings from the cavity where the rotating field exists. In another embodiment, voltage control and/or switching off of the output is achievable with a variable-coupling generator/motor. A stator is made up of two concentric layers of windings, with a larger number of turns on the inner layer of windings than the outer layer of windings. The windings are to be connected in series electrically, that is, their voltages add vectorially. The mechanical arrangement is such that one or both of the windings can be rotated with respect to the other winding about their common central axis. Another improved design for the stator assembly of electromechanical batteries provides knife switch contacts that are in electrical contact with the stator windings. The operation of this embodiment depends on the fact that an abnormally large torque will be exerted on the stator structure during any short-circuit condition.

Fail safe controllable output improved version of the electromechanical battery

DOEpatents

Post, R.F.

1999-01-19

Mechanical means are provided to control the voltages induced in the windings of a generator/motor. In one embodiment, a lever is used to withdraw or insert the entire stator windings from the cavity where the rotating field exists. In another embodiment, voltage control and/or switching off of the output is achievable with a variable-coupling generator/motor. A stator is made up of two concentric layers of windings, with a larger number of turns on the inner layer of windings than the outer layer of windings. The windings are to be connected in series electrically, that is, their voltages add vectorially. The mechanical arrangement is such that one or both of the windings can be rotated with respect to the other winding about their common central axis. Another improved design for the stator assembly of electromechanical batteries provides knife switch contacts that are in electrical contact with the stator windings. The operation of this embodiment depends on the fact that an abnormally large torque will be exerted on the stator structure during any short-circuit condition. 4 figs.

Visiting the Gödel universe.

PubMed

Grave, Frank; Buser, Michael

2008-01-01

Visualization of general relativity illustrates aspects of Einstein's insights into the curved nature of space and time to the expert as well as the layperson. One of the most interesting models which came up with Einstein's theory was developed by Kurt Gödel in 1949. The Gödel universe is a valid solution of Einstein's field equations, making it a possible physical description of our universe. It offers remarkable features like the existence of an optical horizon beyond which time travel is possible. Although we know that our universe is not a Gödel universe, it is interesting to visualize physical aspects of a world model resulting from a theory which is highly confirmed in scientific history. Standard techniques to adopt an egocentric point of view in a relativistic world model have shortcomings with respect to the time needed to render an image as well as difficulties in applying a direct illumination model. In this paper we want to face both issues to reduce the gap between common visualization standards and relativistic visualization. We will introduce two techniques to speed up recalculation of images by means of preprocessing and lookup tables and to increase image quality through a special optimization applicable to the Gödel universe. The first technique allows the physicist to understand the different effects of general relativity faster and better by generating images from existing datasets interactively. By using the intrinsic symmetries of Gödel's spacetime which are expressed by the Killing vector field, we are able to reduce the necessary calculations to simple cases using the second technique. This even makes it feasible to account for a direct illumination model during the rendering process. Although the presented methods are applied to Gödel's universe, they can also be extended to other manifolds, for example light propagation in moving dielectric media. Therefore, other areas of research can benefit from these generic improvements.

Extensión del Formalismo de Orbitales de Defecto Cuántico al tratamiento del efecto Stark (SQDO).

NASA Astrophysics Data System (ADS)

Menéndez, J. M.; Martín, I.; Velasco, A. M.

El estudio experimental de las interacciones de átomos Rydberg altamente excitados con campos eléctricos ha experimentado un creciente interés durante las dos últimas décadas debido, en gran medida, al desarrollo de nuevas técnicas para crear y estudiar átomos Rydberg en el laboratorio. Acompañando a estas nuevas técnicas experimentales, es necesario el desarrollo de modelos teóricos que nos permitan contrastar sus medidas y conocer mejor los fundamentos de los mismos. Desde el punto de vista teórico el conocimiento del desdoblamiento de los niveles energéticos de un átomo en función de la magnitud del campo eléctrico aplicado (lo que se conoce como mapa Stark) es el mejor punto de partida para la descripción del sistema y un prerrequisito fundamental para el cálculo de distintas propiedades atómicas en presencia del campo eléctrico tales como intensidades de transición, umbrales de ionización de campo eléctrico, tiempos de vida, posición y anchura de cruces evitados, etc. En este trabajo presentamos la adaptación del método de orbitales de defecto cuántico [1,2,3] al tratamiento del efecto Stark (SQDO) [4] y su aplicación al cálculo de los desdoblamientos energéticos y fuerzas de oscilador de estados Rydberg en los átomos de Li, Na y K. El propósito de este estudio es, por un lado, desarrollar métodos fiables para la determinación de propiedades atómicas en presencia de campos eléctricos y, por otro, mostrar la fiabilidad de las funciones de onda QDO en la descripción del efecto Stark en sistemas atómicos.

Permanent magnet machine with windings having strand transposition

DOEpatents

Qu, Ronghai; Jansen, Patrick Lee

2009-04-21

This document discusses, among other things, a stator with transposition between the windings or coils. The coils are free from transposition to increase the fill factor of the stator slots. The transposition at the end connections between an inner coil and an outer coil provide transposition to reduce circulating current loss. The increased fill factor reduces further current losses. Such a stator is used in a dual rotor, permanent magnet machine, for example, in a compressor pump, wind turbine gearbox, wind turbine rotor.

Influence of winding construction on starter-generator thermal processes

NASA Astrophysics Data System (ADS)

Grachev, P. Yu; Bazarov, A. A.; Tabachinskiy, A. S.

2018-01-01

Dynamic processes in starter-generators features high winding are overcurrent. It can lead to insulation overheating and fault operation mode. For hybrid and electric vehicles, new high efficiency construction of induction machines windings is proposed. Stator thermal processes need be considered in the most difficult operation modes. The article describes construction features of new compact stator windings, electromagnetic and thermal models of processes in stator windings and explains the influence of innovative construction on thermal processes. Models are based on finite element method.

Experimental rotordynamic coefficient results for honeycomb seals

NASA Technical Reports Server (NTRS)

Elrod, David A.; Childs, Dara W.

1988-01-01

Test results (leakage and rotordynamic coefficients) are presented for seven honeycomb-stator smooth-rotor seals. Tests were carried out with air at rotor speeds up to 16,000 cpm and supply pressures up to 8.2 bars. Test results for the seven seals are compared, and the most stable configuration is identified based on the whirl frequency ratio. Results from tests of a smooth-rotor/smooth-stator seal, a teeth-on-stator labyrinth seal, and the most stable honeycomb seal are compared.

Gödel universes in string theory

NASA Astrophysics Data System (ADS)

Barrow, John D.; Dabrowski, Mariusz P.

1998-11-01

We show that homogeneous Gödel spacetimes need not contain closed timelike curves in low-energy-effective string theories. We find exact solutions for the Gödel metric in string theory for the full O(α') action including both dilaton and axion fields. The results are valid for bosonic, heterotic and super-strings. To first order in the inverse string tension α', these solutions display a simple relation between the angular velocity of the Gödel universe, Ω, and the inverse string tension of the form α'=1/Ω2 in the absence of the axion field. The generalization of this relationship is also found when the axion field is present.

Field-circuit analysis and measurements of a single-phase self-excited induction generator

NASA Astrophysics Data System (ADS)

Makowski, Krzysztof; Leicht, Aleksander

2017-12-01

The paper deals with a single-phase induction machine operating as a stand-alone self-excited single-phase induction generator for generation of electrical energy from renewable energy sources. By changing number of turns and size of wires in the auxiliary stator winding, an improvement of performance characteristics of the generator were obtained as regards no-load and load voltage of the stator windings as well as stator winding currents of the generator. Field-circuit simulation models of the generator were developed using Flux2D software package for the generator with shunt capacitor in the main stator winding. The obtained results have been validated experimentally at the laboratory setup using the single-phase capacitor induction motor of 1.1 kW rated power and 230 V voltage as a base model of the generator.

Permanent-magnet switched-flux machine

DOEpatents

Trzynadlowski, Andrzej M.; Qin, Ling

2012-02-21

A permanent-magnet switched-flux (PMSF) device has an outer rotor mounted to a shaft about a central axis extending axially through the PMSF device. First and second pluralities of permanent-magnets (PMs) are respectively mounted in first and second circles, radially outwardly in first and second transverse planes extending from first and second sections of the central axis adjacent to an inner surface of the outer rotor. An inner stator is coupled to the shaft and has i) a stator core having a core axis co-axial with the central axis; and ii) first and second pluralities of stator poles mounted in first and second circles, radially outwardly from the stator core axis in the first and second transverse planes. The first and second pluralities of PMs each include PMs of alternating polarity.

Permanent-magnet switched-flux machine

DOEpatents

Trzynadlowski, Andrzej M.; Qin, Ling

2011-06-14

A permanent-magnet switched-flux (PMSF) device has an outer rotor mounted to a shaft about a central axis extending axially through the PMSF device. First and second pluralities of permanent-magnets (PMs) are respectively mounted in first and second circles, radially outwardly in first and second transverse planes extending from first and second sections of the central axis adjacent to an inner surface of the outer rotor. An inner stator is coupled to the shaft and has i) a stator core having a core axis co-axial with the central axis; and ii) first and second pluralities of stator poles mounted in first and second circles, radially outwardly from the stator core axis in the first and second transverse planes. The first and second pluralities of PMs each include PMs of alternating polarity.

Cold-air performance of a 12.766-centimeter-tip-diameter axial-flow cooled turbine. 3: Effect of rotor tip clearance on overall performance of a solid blade configuration

NASA Technical Reports Server (NTRS)

Haas, J. E.; Kofskey, M. G.

1977-01-01

Two tip clearance configurations, one with a recess in the casing and the other with a reduced rotor blade height, were investigated at design equivalent speed over a range of tip clearance from about 2.0 to 5.0 percent of the stator blade height. The optimum configuration with a recess in the casing was the one where the rotor tip diameter was equal to the stator tip diameter (zero blade extension). For this configuration there was an approximate 1.5 percent decrease in total efficiency for an increase in tip clearance of 1 percent of stator blade height. For the reduced blade height configurations there was an approximate 2.0 percent decrease in total efficiency for an increase in tip clearance of 1 percent of stator blade height.

Influence of rubbing on rotor dynamics, part 2

NASA Technical Reports Server (NTRS)

Muszynska, Agnes; Bently, Donald E.; Franklin, Wesley D.; Hayashida, Robert D.; Kingsley, Lori M.; Curry, Arthur E.

1989-01-01

Rotor dynamic behavior depends considerably on how much the specific physical phenomena accompanying rotor rubbing against the stator is involved. The experimental results of rotor-to-stator rubbing contact are analyzed. The computer code is described for obtaining numerical calculations of rotor-to-stator rubbing system dynamic responses. Computer generated results are provided. The reduced dynamic data from High Pressure Fuel Turbo Pump (HPFTP) hot fire test are given. The results provide some significant conclusions. Information is provided on the electronic instrumentation used in the experimental testing.

Calidad de Imagen del Telescopio UNAM212

NASA Astrophysics Data System (ADS)

Cobos, F. J.; Teiada de Vargas, C.

1987-05-01

El telescopio UNAM2l2, del Observatorio Astronómico Nacional, situado en la Sierra de San Pedro Mártir (Baja California, México), cumplira en un futuro muy cercano siete años de uso para fines de investigación astronómica. Aunque en este tiempo no se ha efectuado un estudio sistemático acerca de su comportamiento óptico y de los factores que influyen en la calidad de las imágenes, se han realizado pruebas diversas, estudios parciales y reuniones especificas, cuyos resultados no siempre se han difundido ampliamente y generalmente no se han presentado por escrito. Es por ello que hemos creido necesario intentar una recopilación de la información existente para poder con ella establecer un diagnóstjco que, aunque no sea definitivo, sirva de base para futuros trabajos tendientes a optimizar el comportamiento óptico del telescopio. Es evidente que un buen número de las conclusiones que se presentan son resultado del trabajo de muchas personas ó de esfuerzos colectivos. Asimismo, hemos tratado de localizar información bibliográfica que pueda ser de utilidad. Nuestro objetivo primordial ha consistido en centrarnos en la óptica del telescopio y su calidad, pero también se han considerado otros aspectos que puedan afectar las imágenes obtenidas tales como: celda del primario, `seeing' local y externo, flexiones posibles en la estructura mecánica del telescopio, etc.

Conservacion de truchas del Pacifico

Treesearch

Brooke E. Penaluna

2016-01-01

La historia de las truchas del Pacífico, pertenecientes al género Oncorhynchus, es una historia muy interesante que se basa en la persistencia y diversificación de sus especies debido, en gran parte, al dinamismo propio que existe en su medio ambiente. Desde el oeste de Norteamérica, extendiéndose hasta el este de Asia, las truchas del Pacífico han experimentado la...

Far-Field Acoustic Characteristics of Multiple Blade-Vane Configurations for a High Tip Speed Fan

NASA Technical Reports Server (NTRS)

Woodward, Richard P.; Gazzaniga, John A.; Hughes, Christopher

2004-01-01

The acoustic characteristics of a model high-speed fan stage were measured in the NASA Glenn 9- by 15-Foot Low Speed Wind Tunnel at takeoff and approach flight conditions. The fan was designed for a corrected rotor tip speed of 442 m/s (1450 ft/s), and had a powered core, or booster stage, giving the model a nominal bypass ratio of 5. A simulated engine pylon and nozzle bifurcation was contained within the bypass duct. The fan stage consisted of all combinations of 3 possible rotors, and 3 stator vane sets. The 3 rotors were (1) wide chord, (2) forward swept, and (3) shrouded. The 3 stator sets were (1) baseline, moderately swept, (2) swept and leaned, and (3) swept integral vane/frame which incorporated some of the swept and leaned features as well as eliminated the downstream support structure. The baseline configuration is considered to be the wide chord rotor with the radial vane stator. A flyover Effective Perceived Noise Level (EPNL) code was used to generate relative EPNL values for the various configurations. The swept and leaned stator showed a 3 EPNdB reduction at lower fan speeds relative to the baseline stator; while the swept integral vane/frame stator showed lowest noise levels at high fan speeds. The baseline, wide chord rotor was typically the quietest of the three rotors. A tone removal study was performed to assess the acoustic benefits of removing the fundamental rotor interaction tone and its harmonics. Reprocessing the acoustic results with the bypass tone removed had the most impact on reducing fan noise at transonic rotor speeds. Removal of the bypass rotor interaction tones (BPF and nBPF) showed up to a 6 EPNdB noise reduction at transonic rotor speeds relative to noise levels for the baseline (wide chord rotor and radial stator; all tones present) configuration.

RTOD- RADIAL TURBINE OFF-DESIGN PERFORMANCE ANALYSIS

NASA Technical Reports Server (NTRS)

Glassman, A. J.

1994-01-01

The RTOD program was developed to accurately predict radial turbine off-design performance. The radial turbine has been used extensively in automotive turbochargers and aircraft auxiliary power units. It is now being given serious consideration for primary powerplant applications. In applications where the turbine will operate over a wide range of power settings, accurate off-design performance prediction is essential for a successful design. RTOD predictions have already illustrated a potential improvement in off-design performance offered by rotor back-sweep for high-work-factor radial turbines. RTOD can be used to analyze other potential performance enhancing design features. RTOD predicts the performance of a radial turbine (with or without rotor blade sweep) as a function of pressure ratio, speed, and stator setting. The program models the flow with the following: 1) stator viscous and trailing edge losses; 2) a vaneless space loss between the stator and the rotor; and 3) rotor incidence, viscous, trailing-edge, clearance, and disk friction losses. The stator and rotor viscous losses each represent the combined effects of profile, endwall, and secondary flow losses. The stator inlet and exit and the rotor inlet flows are modeled by a mean-line analysis, but a sector analysis is used at the rotor exit. The leakage flow through the clearance gap in a pivoting stator is also considered. User input includes gas properties, turbine geometry, and the stator and rotor viscous losses at a reference performance point. RTOD output includes predicted turbine performance over a specified operating range and any user selected flow parameters. The RTOD program is written in FORTRAN IV for batch execution and has been implemented on an IBM 370 series computer with a central memory requirement of approximately 100K of 8 bit bytes. The RTOD program was developed in 1983.

DESIGN ANALYSIS OF RADIAL INFLOW TURBINES

NASA Technical Reports Server (NTRS)

Glassman, A. J.

1994-01-01

This program performs a velocity-diagram analysis required for determining geometry and estimating performance for radial-inflow turbines. Input design requirements are power, mass flow rate, inlet temperature and pressure, and rotative rate. The design variables include stator-exit angle, rotor-exit-tip to rotor-inlet radius ratio, rotor-exit-hub to tip radius ratio, and the magnitude and radial distribution of rotor-exit tangential velocity. The program output includes diameters, total and static efficiences, all absolute and relative temperatures, pressures, and velocities, and flow angles at stator inlet, stator exit, rotor inlet, and rotor exit. Losses accounted for in this program by the internal loss model are three-dimensional (profile plus end wall) viscous losses in the stator and the rotor, the disk-friction loss on the back side of the rotor, the loss due to the clearance between the rotor tip and the outer casing, and the exit velocity loss. The flow analysis is one-dimensional at the stator inlet, stator exit, and rotor inlet, each of these calculation stations being at a constant radius. At the rotor exit where there is a variation in flow-field radius, an axisymmetric two-dimensional analysis is made using constant height sectors. Simple radial equilibrium is used to establish the static pressure gradient at the rotor exit. This program is written in FORTRAN V and has been implemented on a UNIVAC 1100 series computer with a memory requirement of approximately 22K of 36 bit words.

Study on stable equilibrium of levitated impeller in rotary pump with passive magnetic bearings.

PubMed

Qian, K X; Wan, F K; Ru, W M; Zeng, P; Yuan, H Y

2006-01-01

It is widely acknowledged that the permanent maglev cannot achieve stable equilibrium; the authors have developed, however, a stable permanent maglev centrifugal blood pump. Permanent maglev needs no position detection and feedback control of the rotor, nevertheless the eccentric distance (ED) and vibration amplitude (VA) of the levitator have been measured to demonstrate the levitation and to investigate the factors affecting levitation. Permanent maglev centrifugal impeller pump has a rotor and a stator. The rotor is driven by stator coil and levitated by two passive magnetic bearings. The rotor position is measured by four Hall sensors, which are distributed evenly and peripherally on the end of the stator against the magnetic ring of the bearing on the rotor. The voltage differences of the sensors due to different distances between the sensors and the magnetic ring are converted into ED. The results verify that the rotor can be disaffiliated from the stator if the rotating speed and the flow rate of the pump are large enough, that is, the maximal ED will reduce to about half of the gap between the rotor and the stator. In addition, the gap between rotor and stator and the viscosity of the fluid to be pumped also affect levitation. The former has an optimal value of approximately 2% of the radius of the rotor. For the latter, levitation stability is better with higher viscosity, meaning smaller ED and VA. The pressure to be pumped has no effect on levitation.

Novel maglev pump with a combined magnetic bearing.

PubMed

Onuma, Hiroyuki; Murakami, Michiko; Masuzawa, Toru

2005-01-01

The newly developed pump is a magnetically levitated centrifugal blood pump in which active and passive magnetic bearings are integrated to construct a durable ventricular assist device. The developed maglev centrifugal pump consists of an active magnetic bearing, a passive magnetic bearing, a levitated impeller, and a motor stator. The impeller is set between the active magnetic bearing and the motor stator. The active magnetic bearing uses four electromagnets to control the tilt and the axial position of the impeller. The radial movement of the levitated impeller is restricted with the passive stability dependent upon the top stator and the passive permanent magnetic bearing to reduce the energy consumption and the control system complexity. The top stator was designed based upon a magnetic field analysis to develop the maglev pump with sufficient passive stability in the radial direction. By implementing this analysis design, the oscillating amplitude of the impeller in the radial direction was cut in half when compared with the simple shape stator. This study concluded that the newly developed maglev centrifugal pump displayed excellent levitation performance and sufficient pump performance as a ventricular assist device.

Aeroacoustic Analysis of Turbofan Noise Generation

NASA Technical Reports Server (NTRS)

Meyer, Harold D.; Envia, Edmane

1996-01-01

This report provides an updated version of analytical documentation for the V072 Rotor Wake/Stator Interaction Code. It presents the theoretical derivation of the equations used in the code and, where necessary, it documents the enhancements and changes made to the original code since its first release. V072 is a package of FORTRAN computer programs which calculate the in-duct acoustic modes excited by a fan/stator stage operating in a subsonic mean flow. Sound is generated by the stator vanes interacting with the mean wakes of the rotor blades. In this updated version, only the tonal noise produced at the blade passing frequency and its harmonics, is described. The broadband noise component analysis, which was part of the original report, is not included here. The code provides outputs of modal pressure and power amplitudes generated by the rotor-wake/stator interaction. The rotor/stator stage is modeled as an ensemble of blades and vanes of zero camber and thickness enclosed within an infinite hard-walled annular duct. The amplitude of each propagating mode is computed and summed to obtain the harmonics of sound power flux within the duct for both upstream and downstream propagating modes.

Full-order observer for direct torque control of induction motor based on constant V/F control technique.

PubMed

Pimkumwong, Narongrit; Wang, Ming-Shyan

2018-02-01

This paper presents another control method for the three-phase induction motor that is direct torque control based on constant voltage per frequency control technique. This method uses the magnitude of stator flux and torque errors to generate the stator voltage and phase angle references for controlling the induction motor by using constant voltage per frequency control method. Instead of hysteresis comparators and optimum switching table, the PI controllers and space vector modulation technique are used to reduce torque and stator-flux ripples and achieve constant switching frequency. Moreover, the coordinate transformations are not required. To implement this control method, a full-order observer is used to estimate stator flux and overcome the problems from drift and saturation in using pure integrator. The feedback gains are designed by simple manner to improve the convergence of stator flux estimation, especially in low speed range. Furthermore, the necessary conditions to maintain the stability for feedback gain design are introduced. The simulation and experimental results show accurate and stable operation of the introduced estimator and good dynamic response of the proposed control method. Copyright © 2017 ISA. Published by Elsevier Ltd. All rights reserved.

Cogging Torque Minimization in Transverse Flux Machines

DOE Office of Scientific and Technical Information (OSTI.GOV)

Husain, Tausif; Hasan, Iftekhar; Sozer, Yilmaz

2017-02-16

This paper presents the design considerations in cogging torque minimization in two types of transverse flux machines. The machines have a double stator-single rotor configuration with flux concentrating ferrite magnets. One of the machines has pole windings across each leg of an E-Core stator. Another machine has quasi-U-shaped stator cores and a ring winding. The flux in the stator back iron is transverse in both machines. Different methods of cogging torque minimization are investigated. Key methods of cogging torque minimization are identified and used as design variables for optimization using a design of experiments (DOE) based on the Taguchi method.more » A three-level DOE is performed to reach an optimum solution with minimum simulations. Finite element analysis is used to study the different effects. Two prototypes are being fabricated for experimental verification.« less

DOE Office of Scientific and Technical Information (OSTI.GOV)

Husain, Tausif; Hasan, Iftekhar; Sozer, Yilmaz

This paper presents the design considerations in cogging torque minimization in two types of transverse flux machines. The machines have a double stator-single rotor configuration with flux concentrating ferrite magnets. One of the machines has pole windings across each leg of an E-Core stator. Another machine has quasi-U-shaped stator cores and a ring winding. The flux in the stator back iron is transverse in both machines. Different methods of cogging torque minimization are investigated. Key methods of cogging torque minimization are identified and used as design variables for optimization using a design of experiments (DOE) based on the Taguchi method.more » A three-level DOE is performed to reach an optimum solution with minimum simulations. Finite element analysis is used to study the different effects. Two prototypes are being fabricated for experimental verification.« less

Single-stage experimental evaluation of compressor blading with slots and vortex generators, part 5

NASA Technical Reports Server (NTRS)

Brent, J. A.

1972-01-01

An experimental investigation was conducted to determine the extent that slots and vortex generators can increase the efficiency and stable operating range of highly loaded compressor stages. With slots in the rotor and stator, the stage performance both with and without vortex generators was inferior to that achieved with the unslotted blading. However, with vortex generators, stator slots, and an unslotted rotor, the stable operating range increased 25% and the stage peak efficiency increased 2.1% over the values achieved with the unslotted rotor and stator without vortex generators, at design equivalent rotor speed.

Morphology, geology and geochemistry of the "Salar del Gran Bajo del Gualicho" (Rio Negro, Argentina)

USGS Publications Warehouse

Angelucci, A.; Barbieri, M.; Brodtkorb, A.; Ciccacci, S.; Civitelli, G.; De Barrio, R.; Di, Filippo M.; Fredi, P.; Friedman, I.; Lombardi, S.; Schalamuk, A.I.; Toro, B.

1996-01-01

A multidisciplinary study of the Gran Bajo del Gualicho area (Rio Negro - Argentina) was carried out; the aim was to delineate its geological and geomorphological evolution and to estabilish the genesis of salts filling the depression. Climatic conditions were analized first to individuate their role in the present morphogenetic processes; moreover the main morphological features of present landscape were examined as well as the stratigraphy of the outcropping formations, and of the Gran Bajo del Gualicho Formation in particular. Finally, a possible geomorphological evolution of the studied area was traced. Geophysical analyses allowed to estabilish that the paleosurface shaped on the crystalline basement is strongly uneven and shows evidence of the strong tectonic phases it underwent. The result of isotope analyses confirmed that the salt deposits on the Gran Bajo del Gualicho bottom were produced by fresh water evaporation, while strontium isotope ratio suggested that such waters were responsible for solubilization of more ancient evaporitic deposits.

Nevado del Huila, Columbia

NASA Technical Reports Server (NTRS)

2007-01-01

Nevado del Huila Volcano in Colombia is actually a volcanic chain running north to south, capped by a glacier. With peaks ranging in height from 2,600 to 5,780 meters (8,530 to 18,960 feet), Nevado del Huila is a stratovolcano composed of alternating layers of hardened lava, solidified ash, and volcanic rocks. Its first recorded eruption occurred in the mid-sixteenth century. The long-dormant volcano erupted again in mid-April 2007. A few months before the eruption, the Advanced Spaceborne Thermal Emission and Reflection Radiometer (ASTER) on NASA's Terra satellite captured this image of Nevado del Huila, on February 23, 2007. In this image, the bright white area just east of the central summit is ice. Immediately west of the summit are bare rocks, appearing as blue-gray. West of those rocks, white reappears, but this patch of white results from clouds hovering in the nearby valley. In the east, the colors turn to brown (indicating bare rock) and bright green (indicating vegetation). ASTER photographed Nevado del Huila near the end of a long phase of quietude. On April 17, 2007, local authorities recorded seismic activity associated with rock fracturing on the volcano's central summit, according to the ReliefWeb Website. Activity intensified the following day with an eruption and mudflows, forcing thousands of nearby residents to evacuate. As the Associated Press reported, the eruption caused avalanches and floods that wiped away both houses and bridges. It marked the volcano's first recorded eruption since the Spanish colonized the area five centuries earlier. NASA image created by Jesse Allen, using data provided courtesy of the NASA/GSFC/MITI/ERSDAC/JAROS, and U.S./Japan ASTER Science Team.

Turbofan noise generation. Volume 1: Analysis

NASA Astrophysics Data System (ADS)

Ventres, C. S.; Theobald, M. A.; Mark, W. D.

1982-07-01

Computer programs were developed which calculate the in-duct acoustic modes excited by a fan/stator stae operating at subsonic tip speed. Three noise source mechanisms are included: (1) sound generated by the rotor blades interacting with turbulence ingested into, or generated within, the inlet duct; (2) sound generated by the stator vanes interacting with the turbulent wakes of the rotors blades; and (3) sound generated by the stator vanes interacting with the mean velocity deficit wakes of the rotor blades. The fan/stator stage is modeled as an ensemble of blades and vanes of zero camber and thickness enclosed within an infinite hard-walled annular duct. Turbulence drawn into or generated within the inlet duct is modeled as nonhomogeneous and anisotropic random fluid motion, superimposed upon a uniform axial mean flow, and convected with that flow. Equations for the duct mode amplitudes, or expected values of the amplitudes, are derived.

Turbofan noise generation. Volume 1: Analysis

NASA Technical Reports Server (NTRS)

Ventres, C. S.; Theobald, M. A.; Mark, W. D.

1982-01-01

Computer programs were developed which calculate the in-duct acoustic modes excited by a fan/stator stae operating at subsonic tip speed. Three noise source mechanisms are included: (1) sound generated by the rotor blades interacting with turbulence ingested into, or generated within, the inlet duct; (2) sound generated by the stator vanes interacting with the turbulent wakes of the rotors blades; and (3) sound generated by the stator vanes interacting with the mean velocity deficit wakes of the rotor blades. The fan/stator stage is modeled as an ensemble of blades and vanes of zero camber and thickness enclosed within an infinite hard-walled annular duct. Turbulence drawn into or generated within the inlet duct is modeled as nonhomogeneous and anisotropic random fluid motion, superimposed upon a uniform axial mean flow, and convected with that flow. Equations for the duct mode amplitudes, or expected values of the amplitudes, are derived.

SSME seal test program: Test results for hole-pattern damper seals

NASA Technical Reports Server (NTRS)

Childs, D. W.

1985-01-01

The results consisting of direct and transverse force coefficients are presented for thirteen, hole-pattern, damper-seal configurations. The designation damper seal refers to a seal which uses a deliberately roughened stator nd smooth rotor, to increase the net damping force developed by a seal. The designation hole-pattern refers to a stator roughness pattern which is developed by a pattern of round holes while are milled into the stator. All seals tested use the same smooth rotor and have the same constant minimum clearance. The seal tests examined the following major design options: (1) hole-area density, i.e., the proportion of stator surface area consumed by holes; and (2) hole depth, particularly the ratio of hole depth to minimum clearance. In addition, limited data were taken to examine the influence of in-line versus staggered hole patterns and flat-bottomed versus spherical-bottomed holes.

Dual power, constant speed electric motor system

DOEpatents

Kirschbaum, H.S.

1984-07-31

A dual capacity permanent split capacitor electric motor system is provided with a stator having main and auxiliary windings. The main stator winding includes two winding sections which are connected in parallel with each other and across a pair of line terminals while the auxiliary winding is connected in series with a capacitor to form a circuit branch which is connected between the line terminals for operation at a first output power level. Switching means are provided to reconnect the main stator winding sections in series with each other and in series with a second capacitor to form a circuit branch which is connected between the line terminals while the stator auxiliary winding is connected directly between the line terminals for operation at a second output power level. Automatic rotation reversal occurs when the motor switches from the first to the second output power level. 6 figs.

DOE Office of Scientific and Technical Information (OSTI.GOV)

Raminosoa, Tsarafidy; Alexander, James Pellegrino; EL-Refaie, Ayman Mohamed Fawzi

A permanent magnet electrical machine includes a stator having conductive windings wound thereon and one or more permanent magnets embedded in the stator. A magnetic keeper element is positioned on the stator so as to form a magnetic flux path with the permanent magnets, with the magnetic keeper element closing the magnetic flux path of the permanent magnets by providing a low reluctance flux path to magnetic flux generated by the permanent magnets. A vacuum pressure impregnation (VPI) process is performed on the stator to increase a thermal conductivity of the windings, with the VPI process including a curing stepmore » that is performed at a selected temperature. The magnetic keeper element sets an operating point of the permanent magnets to an internal flux density level above a demagnetization threshold associated with the selected temperature at which the curing step is performed.« less

Acoustic mode measurements in the inlet of a model turbofan using a continuously rotating rake

NASA Astrophysics Data System (ADS)

Heidelberg, Laurence J.; Hall, David G.

1993-01-01

Comprehensive measurements of the spinning acoustic mode structure in the inlet of the Advanced Ducted Propeller (ADP) have been completed. These measurements were taken using a unique and previously untried method which was first proposed by T.G. Sofrin. A continuously rotating microphone system was employed. The ADP model was designed and built by Pratt & Whitney and tested in the NASA Lewis 9- by 15-foot Anechoic Wind Tunnel. Three inlet configurations were tested with cut-on and cutoff stator vane sets. The cutoff stator was designed to suppress all modes at the blade passing frequency. Rotating rake measurements indicate that several extraneous circumferential modes were active. The mode orders suggest that their source was an interaction between the rotor and small interruptions in the casing tip treatment. The cut-on stator produced the expected circumferential modes plus higher levels of the unexpected modes seen with the cutoff stator.

Acoustic Mode Measurements in the Inlet of a Model Turbofan Using a Continuously Rotating Rake

NASA Technical Reports Server (NTRS)

Heidelberg, Laurence J.; Hall, David G.

1992-01-01

Comprehensive measurements of the spinning acoustic mode structure in the inlet of the Advanced Ducted Propeller (ADP) have been completed. These measurements were taken using a unique and previously untried method which was first proposed by T.G. Sofrin. A continuously rotating microphone system was employed. The ADP model was designed and built by Pratt & Whitney and tested in the NASA Lewis 9- by 15-foot Anechoic Wind Tunnel. Three inlet configurations were tested with cut-on and cutoff stator vane sets. The cutoff stator was designed to suppress all modes at the blade passing frequency. Rotating rake measurements indicate that several extraneous circumferential modes were active. The mode orders suggest that their source was an interaction between the rotor and small interruptions in the casing tip treatment. The cut-on stator produced the expected circumferential modes plus higher levels of the unexpected modes seen with the cutoff stator.

Core compressor exit stage study. Volume 1: Blading design. [turbofan engines

NASA Technical Reports Server (NTRS)

Wisler, D. C.

1977-01-01

A baseline compressor test stage was designed as well as a candidate rotor and two candidate stators that have the potential of reducing endwall losses relative to the baseline stage. These test stages are typical of those required in the rear stages of advanced, highly-loaded core compressors. The baseline Stage A is a low-speed model of Stage 7 of the 10 stage AMAC compressor. Candidate Rotor B uses a type of meanline in the tip region that unloads the leading edge and loads the trailing edge relative to the baseline Rotor A design. Candidate Stator B embodies twist gradients in the endwall region. Candidate Stator C embodies airfoil sections near the endwalls that have reduced trailing edge loading relative to Stator A. Tests will be conducted using four identical stages of blading so that the designs described will operate in a true multistage environment.

Dual power, constant speed electric motor system

DOEpatents

Kirschbaum, Herbert S.

1984-01-01

A dual capacity permanent split capacitor electric motor system is provided with a stator having main and auxiliary windings. The main stator winding includes two winding sections which are connected in parallel with each other and across a pair of line terminals while the auxiliary winding is connected in series with a capacitor to form a circuit branch which is connected between the line terminals for operation at a first output power level. Switching means are provided to reconnect the main stator winding sections in series with each other and in series with a second capacitor to form a circuit branch which is connected between the line terminals while the stator auxiliary winding is connected directly between the line terminals for operation at a second output power level. Automatic rotation reversal occurs when the motor switches from the first to the second output power level.

Calidad del aire interior en las escuelas

EPA Pesticide Factsheets

EPA ha desarrollado el Programa de Herramientas de Calidad del Aire Interior para las Escuelas para reducir la exposición a los contaminantes ambientales en las mismas a través de la adopción voluntaria de las prácticas para manejar la calidad del aire int

A computational analysis of the aerodynamic and aeromechanical behavior of the purdue multistage compressor

NASA Astrophysics Data System (ADS)

Monk, David James Winchester

Compressor design programs are becoming more reliant on computational tools to predict and optimize aerodynamic and aeromechanical behavior within a compressor. Recent trends in compressor development continue to push for more efficient, lighter weight, and higher performance machines. To meet these demands, designers must better understand the complex nature of the inherently unsteady flow physics inside of a compressor. As physical testing can be costly and time prohibitive, CFD and other computational tools have become the workhorse during design programs. The objectives of this research were to investigate the aerodynamic and aeromechanical behavior of the Purdue multistage compressor, as well as analyze novel concepts for reducing rotor resonant responses in compressors. Advanced computational tools were utilized to allow an in-depth analysis of the flow physics and structural characteristics of the Purdue compressor, and complement to existing experimental datasets. To analyze the aerodynamic behavior of the compressor a Rolls-Royce CFD code, developed specifically for multistage turbomachinery flows, was utilized. Steady-state computations were performed using the RANS solver on a single-passage mesh. Facility specific boundary conditions were applied to the model, increasing the model fidelity and overall accuracy of the predictions. Detailed investigations into the overall compressor performance, stage performance, and individual blade row performance were completed. Additionally, separation patterns on stator vanes at different loading conditions were investigated by plotting pathlines near the stator suction surfaces. Stator cavity leakage flows were determined to influence the size and extent of stator hub separations. In addition to the aerodynamic analysis, a Rolls-Royce aeroelastic CFD solver was utilized to predict the forced response behavior of Rotor 2, operating at the 1T mode crossing of the Campbell Diagram. This computational tool couples

Effects of vane/blade ratio and spacing on fan noise, volume 1

NASA Technical Reports Server (NTRS)

Gliebe, P. R.; Kantola, R. A.

1983-01-01

The noise characteristics of a high-speed fan were studied. The experimental investigation was carried out on a 50.8 cm (20 in.) diameter scale model fan stage in an anechoic chamber with an inflow turbulence control screen installed. The forty-four blade rotor was tested with forty-eight vane and eighty-six vane stator rows, over a range of aixal rotor-stator spacings from 0.5 to 2.3 rotor tip chords. A two-dimensional strip theory model of rotor-stator interaction noise was employed to predict the measured tone power level trends, and good overall agreement with measured trends was obtained.

Halbach array generator/motor having an automatically regulated output voltage and mechanical power output

DOEpatents

Post, Richard F.

2005-02-22

A motor/generator having its stationary portion, i.e., the stator, positioned concentrically within its rotatable element, i.e., the rotor, along its axis of rotation. The rotor includes a Halbach array. The stator windings are switched or commutated to provide a DC motor/generator much the same as in a conventional DC motor/generator. The voltage and power are automatically regulated by using centrifugal force to change the diameter of the rotor, and thereby vary the radial gap in between the stator and the rotating Halbach array, as a function of the angular velocity of the rotor.

Direct control of air gap flux in permanent magnet machines

DOEpatents

Hsu, John S.

2000-01-01

A method and apparatus for field weakening in PM machines uses field weakening coils (35, 44, 45, 71, 72) to produce flux in one or more stators (34, 49, 63, 64), including a flux which counters flux normally produced in air gaps between the stator(s) (34, 49, 63, 64) and the rotor (20, 21, 41, 61) which carries the PM poles. Several modes of operation are introduced depending on the magnitude and polarity of current in the field weakening coils (35, 44, 45, 71, 72). The invention is particularly useful for, but not limited to, the electric vehicle drives and PM generators.

Travelling wave ultrasonic motor using the B08 flexural mode of a circular membrane.

PubMed

Rayner, P J; Whatmore, R W

2001-05-01

This paper describes the design, construction, and performance of a piezoelectric motor that uses the travelling B08 mode of an 80-mm diameter circular membrane to drive a rotor by frictional contact. The motor is of a thin planar design, giving high torque of up to 0.33 Nm at low speed and has been developed as a design that can be made with lithographic techniques for miniaturization. Investigations of the free stator with a vibration pattern imager and impedance analyzer gave the resonance frequency, mode, and electromechanical coupling of the stator. Motor speed as a function of frequency for a constant voltage and performance charts of speed, output power, and efficiency against torque are presented for a particular input voltage and rotor pre-load. The effects of two different lead zirconate titanate (PZT) ring dimensions have been investigated. Excitation of the B09 mode has been observed, incommensurate with the piezoelectric excitation of the stator. This is discussed with relation to edge-clamping of the stator. Single standing wave motoring was observed, believed to arise from asymmetry of the stator and its perturbation of the B08 resonance mode. Sources of power loss, including frame vibration and friction interface slip, are considered and discussed.

A novel flux-switching permanent magnet machine with v-shaped magnets

NASA Astrophysics Data System (ADS)

Zhao, Guishu; Hua, Wei

2017-05-01

In this paper, firstly a novel 6-stator-coil/17-rotor-pole (6/17) flux-switching permanent magnet (FSPM) machine with V-shaped magnets, deduced from conventional 12/17 FSPM machines is proposed to achieve more symmetrical phase back-electromotive force (back-EMF), and smaller torque ripple by comparing with an existing 6/10 V-shaped FSPM machine. Then, to obtain larger electromagnetic torque, less torque ripple, and easier mechanical processing, two improved variants based on the original 6/17 V-shaped topology are proposed. For the first variant, the separate stator-core segments located on the stator yoke are connected into a united stator yoke, while for the second variant the stator core is a whole entity by adding magnetic bridges at the ends of permanent magnets (PMs). Consequently, the performances of the three 6/17 V-shaped FSPM machines, namely, the original one and the two variants, are conducted by finite element analysis (FEA). The results reveal that the first variant exhibits significantly larger torque and considerably improved torque per magnet volume, i.e., the magnet utilization ratio than the original one, and the second variant exhibits the smallest torque ripple, least total harmonic distribution (THD) of phase back-EMF, and easiest mechanical processing for manufacturing.

May Gödel's Ideas Be Addressed Philosophically?

NASA Astrophysics Data System (ADS)

Dokulil, Miloš

2007-11-01

Gödel emphasised philosophy as an important tool in science. Much less is known about his religious background. We should bear in mind that our evaluational perspective differs very much from the one in which Gödel lived. He was personally sure that there must be another existence after death-an afterlife (''of unlimited life span''). As a ''Baptized Lutheran'' he did not include ''Trinity'' in his creed. He was also certain that mind is separate from matter. This text tries to include Libet's ''readiness potential'' into the debate concerning the specificity of the mind. Neither Gödel's identification of materialism with mechanism nor his vision of the ''spirit'' are a viable solution of the problem.

Noise generated by convected gusts interacting with swept airfoil cascades

NASA Astrophysics Data System (ADS)

Envia, E.; Kerschen, E. J.

1986-07-01

An analysis is developed for the noise generated by the interaction of a rotor viscous wake with a cascade of swept stator vanes. The stator vanes span a channel formed by infinite parallel walls and containing a subsonic mean flow. High frequency interactions, for which the noise generation is concentrated at the vane leading edge, are considered. The analysis utilizes a superposition of the solution to the isolated stator vane problem, presented in an earlier paper, to develop an approximate solution to the cascade problem. The rotor wake model includes the features of wake circumferential lean and a linear spanwise variation of the magnitude of the wake deficit velocity. Calculations are presented which show that, for rotor wakes with moderate circumferential lean, stator sweep produces substantial reductions in noise level. The vane sweep must be oriented to enhance the phase lags along the vane leading edge produced by wake lean. The noise levels are found to be fairly insensitive to spanwise variations in the wake deficit.

A novel L-shaped linear ultrasonic motor operating in a single resonance mode

NASA Astrophysics Data System (ADS)

Zhang, Bailiang; Yao, Zhiyuan; Liu, Zhen; Li, Xiaoniu

2018-01-01

In this study, a large thrust linear ultrasonic motor using an L-shaped stator is described. The stator is constructed by two mutually perpendicular rectangular plate vibrators, one of which is mounted in parallel with the slider to make the motor structure to be more compact. The symmetric and antisymmetric modes of the stator based on the first order bending vibration of two vibrators are adopted, in which each resonance mode is assigned to drive the slider in one direction. The placement of piezoelectric ceramics in a stator could be determined by finite element analysis, and the influence of slots in the head block on the vibration amplitudes of driving foot was studied as well. Three types of prototypes (non-slotted, dual-slot, and single-slot) were fabricated and experimentally investigated. Experimental results demonstrated that the prototype with one slot exhibited the best mechanical output performance. The maximum loads under the excitation of symmetric mode and antisymmetric mode were 65 and 90 N, respectively.

Modeling and experimental analysis of the linear ultrasonic motor with in-plane bending and longitudinal mode.

PubMed

Wan, Zhijian; Hu, Hong

2014-03-01

A novel linear ultrasonic motor based on in-plane longitudinal and bending mode vibration is presented in this paper. The stator of the motor is composed of a metal plate and eight piezoelectric ceramic patches. There are four long holes in the plate, designed for consideration of the longitudinal and bending mode coupling. The corresponding model is developed to optimize the mechanical and electrical coupling of the stator, which causes an ellipse motion at the contact tip of the stator when the composite vibrations with longitudinal and bending are excited. Its harmonic and transient responses are simulated and inspected. A prototype based on the model is fabricated and used to conduct experiments. Results show that the amplitude of the stator's contact tips is significantly increased, which helps to amplify the driving force and speed of the motor. It is therefore feasible to implement effective linear movement using the developed prototype. Copyright © 2013 Elsevier B.V. All rights reserved.

A novel L-shaped linear ultrasonic motor operating in a single resonance mode.

PubMed

Zhang, Bailiang; Yao, Zhiyuan; Liu, Zhen; Li, Xiaoniu

2018-01-01

In this study, a large thrust linear ultrasonic motor using an L-shaped stator is described. The stator is constructed by two mutually perpendicular rectangular plate vibrators, one of which is mounted in parallel with the slider to make the motor structure to be more compact. The symmetric and antisymmetric modes of the stator based on the first order bending vibration of two vibrators are adopted, in which each resonance mode is assigned to drive the slider in one direction. The placement of piezoelectric ceramics in a stator could be determined by finite element analysis, and the influence of slots in the head block on the vibration amplitudes of driving foot was studied as well. Three types of prototypes (non-slotted, dual-slot, and single-slot) were fabricated and experimentally investigated. Experimental results demonstrated that the prototype with one slot exhibited the best mechanical output performance. The maximum loads under the excitation of symmetric mode and antisymmetric mode were 65 and 90 N, respectively.

Efecto del Programa de Entrenamiento “Manejo del Dolor” en la Documentación de Enfermería en el Expediente Electrónico

PubMed Central

Monsiváis, María Guadalupe Moreno; Guzmán, Ma. Guadalupe Interial; Flores, Paz Francisco Sauceda; Arreola, Leticia Vázquez

2012-01-01

Resumen En el presente trabajo se muestra la importancia de entrenar al personal de enfermería para mejorar la documentación en el expediente electrónico. Se eligió el manejo del dolor por ser un área prioritaria; una alta proporción de pacientes en período post operatorio cursa con dolor, por lo tanto, la documentación debe ser útil para la toma de decisiones clínicas. Se implementó un programa de entrenamiento denominado “Manejo del Dolor” dirigido al personal de enfermería. Se utilizó la tecnología de la información como herramienta para fortalecer el conocimiento con base en la revisión sistemática de la literatura; el personal de enfermería participante seleccionó la mejor evidencia; posteriormente se trabajó en la transferencia de este conocimiento a la práctica a través del diseño de un protocolo para el manejo del dolor. Se concluye que el conocimiento del manejo del dolor es fundamental para que enfermería documente con mayor precisión sus intervenciones. PMID:24199106

Comparison of Far-Field Noise for Three Significantly Different Model Turbofans

NASA Technical Reports Server (NTRS)

Woodward, Richard P.

2008-01-01

Far-field noise sound power level (PWL) spectra and overall sound pressure level (OASPL) directivities were compared for three significantly different model fan stages which were tested in the NASA Glenn 9x15 Low Speed Wind Tunnel. The test fans included the Advanced Ducted Propulsor (ADP) Fan1, the baseline Source Diagnostic Test (SDT) fan, and the Quiet High Speed Fan2 (QHSF2) These fans had design rotor tangential tip speeds from 840 to 1474 ft/s and stage pressure ratios from 1.29 to 1.82. Additional parameters included rotor-stator spacing, stator sweep, and downstream support struts. Acoustic comparison points were selected on the basis of stage thrust. Acoustic results for the low tip speed/low pressure ratio fan (ADP Fan1) were thrust-adjusted to show how a geometrically-scaled version of this fan might compare at the higher design thrust levels of the other two fans. Lowest noise levels were typically observed for ADP Fan1 (which had a radial stator) and for the intermediate tip speed fan (Source Diagnostics Test, SDT, R4 rotor) with a swept stator. Projected noise levels for the ADP fan to the SDT swept stator configuration at design point conditions showed the fans to have similar noise levels. However, it is possible that the ADP fan could be 2 to 3 dB quieter with incorporation of a swept stator. Benefits of a scaled ADP fan include avoidance of multiple pure tones associated with transonic and higher blade tip speeds. Penalties of a larger size ADP fan would include increased nacelle size and drag.

Comparison of Far-field Noise for Three Significantly Different Model Turbofans

NASA Technical Reports Server (NTRS)

Woodward, Richard P.

2008-01-01

Far-field noise sound power level (PWL) spectra and overall sound pressure level (OASPL) directivities were compared for three significantly different model fan stages which were tested in the NASA Glenn 9 15 Low Speed Wind Tunnel. The test fans included the Advanced Ducted Propulsor (ADP) Fan1, the baseline Source Diagnostic Test (SDT) fan, and the Quiet High Speed Fan2 (QHSF2). These fans had design rotor tangential tip speeds from 840 to 1474 ft/s and stage pressure ratios from 1.29 to 1.82. Additional parameters included rotor-stator spacing, stator sweep, and downstream support struts. Acoustic comparison points were selected on the basis of stage thrust. Acoustic results for the low tip speed/low pressure ratio fan (ADP Fan1) were thrust-adjusted to show how a geometrically-scaled version of this fan might compare at the higher design thrust levels of the other two fans. Lowest noise levels were typically observed for ADP Fan1 (which had a radial stator) and for the intermediate tip speed fan (Source Diagnostics Test, SDT, R4 rotor) with a swept stator. Projected noise levels for the ADP fan to the SDT swept stator configuration at design point conditions showed the fans to have similar noise levels. However, it is possible that the ADP fan could be 2 to 3 dB quieter with incorporation of a swept stator. Benefits of a scaled ADP fan include avoidance of multiple pure tones associated with transonic and higher blade tip speeds. Penalties of a larger size ADP fan would include increased nacelle size and drag.

Computational Assessment of a 3-Stage Axial Compressor Which Provides Airflow to the NASA 11- by 11-Foot Transonic Wind Tunnel, Including Design Changes for Increased Performance

NASA Technical Reports Server (NTRS)

Kulkarni, Sameer; Beach, Timothy A.; Jorgenson, Philip C.; Veres, Joseph P.

2017-01-01

A 24 foot diameter 3-stage axial compressor powered by variable-speed induction motors provides the airflow in the closed-return 11- by 11-Foot Transonic Wind Tunnel (11-Foot TWT) Facility at NASA Ames Research Center at Moffett Field, California. The facility is part of the Unitary Plan Wind Tunnel, which was completed in 1955. Since then, upgrades made to the 11-Foot TWT such as flow conditioning devices and instrumentation have increased blockage and pressure loss in the tunnel, somewhat reducing the peak Mach number capability of the test section. Due to erosion effects on the existing aluminum alloy rotor blades, fabrication of new steel rotor blades is planned. This presents an opportunity to increase the Mach number capability of the tunnel by redesigning the compressor for increased pressure ratio. Challenging design constraints exist for any proposed design, demanding the use of the existing driveline, rotor disks, stator vanes, and hub and casing flow paths, so as to minimize cost and installation time. The current effort was undertaken to characterize the performance of the existing compressor design using available design tools and computational fluid dynamics (CFD) codes and subsequently recommend a new compressor design to achieve higher pressure ratio, which directly correlates with increased test section Mach number. The constant cross-sectional area of the compressor leads to highly diffusion factors, which presents a challenge in simulating the existing design. The CFD code APNASA was used to simulate the aerodynamic performance of the existing compressor. The simulations were compared to performance predictions from the HT0300 turbomachinery design and analysis code, and to compressor performance data taken during a 1997 facility test. It was found that the CFD simulations were sensitive to endwall leakages associated with stator buttons, and to a lesser degree, under-stator-platform flow recirculation at the hub. When stator button leakages were

Brushless machine having ferromagnetic side plates and side magnets

DOEpatents

Hsu, John S

2012-10-23

An apparatus is provided having a cylindrical stator and a rotor that is spaced from a stator to define an annular primary air gap that receives AC flux from the stator. The rotor has a plurality of longitudinal pole portions disposed parallel to the axis of rotation and alternating in polarity around a circumference of the rotor. Each longitudinal pole portion includes portions of permanent magnet (PM) material and at least one of the longitudinal pole portions has a first end and an opposing second end and a side magnet is disposed adjacent the first end and a side pole is disposed adjacent the second end.

Six pole/eight pole single-phase motor

DOEpatents

Kirschbaum, Herbert S.

1984-01-01

A single phase alternating current electric motor is provided with a main stator winding having two coil groups which are connected to form eight poles for eight-pole operation and to form six poles for six-pole operation. Each group contains four series connected coil elements with each element spanning approximately one-seventh of the periphery of the machine. The coil groups are spaced 180 mechanical degrees apart such that each end coil of one group overlaps one of the end coils of the other group. An auxiliary stator winding having two coil groups with the same relative angular displacement as the main stator winding coil groups is included.

Six pole/eight pole single-phase motor

DOEpatents

Kirschbaum, H.S.

1984-07-31

A single phase alternating current electric motor is provided with a main stator winding having two coil groups which are connected to form eight poles for eight-pole operation and to form six poles for six-pole operation. Each group contains four series connected coil elements with each element spanning approximately one-seventh of the periphery of the machine. The coil groups are spaced 180 mechanical degrees apart such that each end coil of one group overlaps one of the end coils of the other group. An auxiliary stator winding having two coil groups with the same relative angular displacement as the main stator winding coil groups is included. 10 figs.

Variable stator radial turbine

NASA Technical Reports Server (NTRS)

Rogo, C.; Hajek, T.; Chen, A. G.

1984-01-01

A radial turbine stage with a variable area nozzle was investigated. A high work capacity turbine design with a known high performance base was modified to accept a fixed vane stagger angle moveable sidewall nozzle. The nozzle area was varied by moving the forward and rearward sidewalls. Diffusing and accelerating rotor inlet ramps were evaluated in combinations with hub and shroud rotor exit rings. Performance of contoured sidewalls and the location of the sidewall split line with respect to the rotor inlet was compared to the baseline. Performance and rotor exit survey data are presented for 31 different geometries. Detail survey data at the nozzle exit are given in contour plot format for five configurations. A data base is provided for a variable geometry concept that is a viable alternative to the more common pivoted vane variable geometry radial turbine.

Impact of Periodic Unsteadiness on Performance and Heat Load in Axial Flow Turbomachines

NASA Technical Reports Server (NTRS)

Sharma, Om P.; Stetson, Gary M.; Daniels, William A,; Greitzer, Edward M.; Blair, Michael F.; Dring, Robert P.

1997-01-01

Results of an analytical and experimental investigation, directed at the understanding of the impact of periodic unsteadiness on the time-averaged flows in axial flow turbomachines, are presented. Analysis of available experimental data, from a large-scale rotating rig (LSRR) (low speed rig), shows that in the time-averaged axisymmetric equations the magnitude of the terms representing the effect of periodic unsteadiness (deterministic stresses) are as large or larger than those due to random unsteadiness (turbulence). Numerical experiments, conducted to highlight physical mechanisms associated with the migration of combustor generated hot-streaks in turbine rotors, indicated that the effect can be simulated by accounting for deterministic stress like terms in the time-averaged mass and energy conservation equations. The experimental portion of this program shows that the aerodynamic loss for the second stator in a 1-1/2 stage turbine are influenced by the axial spacing between the second stator leading edge and the rotor trailing edge. However, the axial spacing has little impact on the heat transfer coefficient. These performance changes are believed to be associated with the change in deterministic stress at the inlet to the second stator. Data were also acquired to quantify the impact of indexing the first stator relative to the second stator. For the range of parameters examined, this effect was found to be of the same order as the effect of axial spacing.

OFF-DESIGN PERFORMANCE OF RADIAL INFLOW TURBINES

NASA Technical Reports Server (NTRS)

Wasserbauer, C. A.

1994-01-01

This program calculates off design performance of radial inflow turbines. The program uses a one dimensional solution of flow conditions through the turbine along the main streamline. The loss model accounts for stator, rotor, incidence, and exit losses. Program features include consideration of stator and rotor trailing edge blockage and computation of performance to limiting load. Stator loss (loss in kinetic energy across the stator) is proportional to the average kinetic energy in the blade row and is represented in the program by an equation which includes a stator loss coefficient determined from design point performance and then assumed to be constant for the off design calculations. Minimum incidence loss does not occur at zero incidence angle with respect to the rotor blade, but at some optimum flow angle. At high pressure ratios the level of rotor inlet velocity seemed to have an excessive influence on the loss. Using the component of velocity in the direction of the optimum flow angle gave better correlations with experimental results. Overall turbine geometry and design point values of efficiency, pressure ratio, and mass flow are needed as input information. The output includes performance and velocity diagram parameters for any number of given speeds over a range of turbine pressure ratio. The program has been implemented on the IBM 7094 and operates in batch mode.

New concepts and new design of permanent maglev rotary artificial heart blood pumps.

PubMed

Qian, K X; Zeng, P; Ru, W M; Yuan, H Y

2006-05-01

According to tradition, permanent maglev cannot achieve stable equilibrium. The authors have developed, to the contrary, two stable permanent maglev impeller blood pumps. The first pump is an axially driven uni-ventricular assist pump, in which the rotor with impeller is radially supported by two passive magnetic bearings, but has one point contact with the stator axially at standstill. As the pump raises its rotating speed, the increasing hydrodynamic force of fluid acting on the impeller will make the rotor taking off from contacting point and disaffiliate from the stator. Then the rotor becomes fully suspended. The second pump is a radially driven bi-ventricular assist pump, i.e., an impeller total artificial heart. Its rotor with two impellers on both ends is supported by two passive magnetic bearings, which counteract the attractive force between rotor magnets and stator coil iron core. The rotor is affiliated to the stator radially at standstill and becomes levitated during rotation. Therefore, the rotor keeps concentric with stator during rotation but eccentric at standstill, as is confirmed by rotor position detection with Honeywell sensors. It concludes that the permanent maglev needs action of a non-magnetic force to achieve stability but a rotating magnetic levitator with high speed and large inertia can maintain its stability merely with passive magnetic bearings.

Rotary sequencing valve with flexible port plate

DOEpatents

Wagner, Glenn Paul

2005-05-10

Rotary sequencing valve comprising a rotor having a rotor face rotatable about an axis perpendicular to the rotor face, wherein the rotor face has a plurality of openings, one or more of which are disposed at a selected radial distance from the axis, and wherein the rotor includes at least one passage connecting at least one pair of the plurality of openings. The valve includes a flexible port plate having a first side and a second side, wherein the first side faces the rotor and engages the rotor such that the flexible port plate can be rotated coaxially by the rotor and can move axially with respect to the rotor, wherein the flexible port plate has a plurality of ports between the first and second sides, which ports are aligned with the openings in the rotor face. The valve also includes a stator having a stator face disposed coaxially with the rotor and the flexible port plate, wherein the second side of the flexible port plate is in sealable, slidable rotary contact with the stator face, wherein the stator face has a plurality of openings, some of which are disposed at the selected radial distance from the axis, and wherein the plurality of openings extend as passages through the stator. The valve may be used in pressure or temperature swing adsorption systems.

33 CFR 110.65 - Indian River Bay, Del.

Code of Federal Regulations, 2012 CFR

2012-07-01

... 33 Navigation and Navigable Waters 1 2012-07-01 2012-07-01 false Indian River Bay, Del. 110.65 Section 110.65 Navigation and Navigable Waters COAST GUARD, DEPARTMENT OF HOMELAND SECURITY ANCHORAGES ANCHORAGE REGULATIONS Special Anchorage Areas § 110.65 Indian River Bay, Del. Beginning at a point bearing...

El Atlas del Bosque Nacional El Yunque

Treesearch

Maya Quiñones; Isabel K. Parés-Ramos; William A. Gould; Grizelle Gonzalez; Kathleen McGinley; Pedro. Ríos

2018-01-01

Esta publicación es un esfuerzo colaborativo entre el Instituto Internacional de Dasonomía Tropical y el Bosque Nacional El Yunque para proveer mapas y análisis de información espacial actualizados sobre una importante reserva natural en Puerto Rico y el único bosque tropical dentro del Sistema de Bosques Nacionales de los Estados Unidos. El Atlas del Bosque Nacional...

Off-Design Performance of Radial-Inflow Turbines

NASA Technical Reports Server (NTRS)

Meitner, P. L.; Glassman, A. J.

1986-01-01

Computer code determines rotor exit flow from hub to tip. RTOD (Radial Turbine Off-Design), computes off-design performance of radial turbine by modeling flow with stator viscous and trailing-edge losses, and with vaneless space loss between stator and rotor, and with rotor incidence, viscous, clearance, trailing-edge, and disk friction losses.

33 CFR 110.65 - Indian River Bay, Del.

Code of Federal Regulations, 2013 CFR

2013-07-01

... 33 Navigation and Navigable Waters 1 2013-07-01 2013-07-01 false Indian River Bay, Del. 110.65... ANCHORAGE REGULATIONS Special Anchorage Areas § 110.65 Indian River Bay, Del. Beginning at a point bearing... State highway bridge across Indian River Inlet; thence 174°, 600 feet; thence 264°, 800 feet; thence 354...

33 CFR 110.65 - Indian River Bay, Del.

Code of Federal Regulations, 2010 CFR

2010-07-01

... 33 Navigation and Navigable Waters 1 2010-07-01 2010-07-01 false Indian River Bay, Del. 110.65... ANCHORAGE REGULATIONS Special Anchorage Areas § 110.65 Indian River Bay, Del. Beginning at a point bearing... State highway bridge across Indian River Inlet; thence 174°, 600 feet; thence 264°, 800 feet; thence 354...

33 CFR 110.65 - Indian River Bay, Del.

Code of Federal Regulations, 2011 CFR

2011-07-01

... 33 Navigation and Navigable Waters 1 2011-07-01 2011-07-01 false Indian River Bay, Del. 110.65... ANCHORAGE REGULATIONS Special Anchorage Areas § 110.65 Indian River Bay, Del. Beginning at a point bearing... State highway bridge across Indian River Inlet; thence 174°, 600 feet; thence 264°, 800 feet; thence 354...

33 CFR 110.65 - Indian River Bay, Del.

Code of Federal Regulations, 2014 CFR

2014-07-01

... 33 Navigation and Navigable Waters 1 2014-07-01 2014-07-01 false Indian River Bay, Del. 110.65... ANCHORAGE REGULATIONS Special Anchorage Areas § 110.65 Indian River Bay, Del. Beginning at a point bearing... State highway bridge across Indian River Inlet; thence 174°, 600 feet; thence 264°, 800 feet; thence 354...

Del-1 Expression as a Potential Biomarker in Triple-Negative Early Breast Cancer.

PubMed

Lee, Soo Jung; Lee, Jeeyeon; Kim, Wan Wook; Jung, Jin Hyang; Park, Ho Yong; Park, Ji-Young; Chae, Yee Soo

2018-01-01

A differential diagnostic role for plasma Del-1 was proposed for early breast cancer (EBC) in our previous study. We examined tumoral Del-1 expression and analyzed its prognostic impact among patients with EBC. Del-1 mRNA expression was assessed in breast epithelial and cancer cells. Meanwhile, the tumoral expression of Del-1 was determined based on tissue microarrays and immunohistochemistry results from 440 patients. While a high Del-1 mRNA expression was found in all the breast cancer cell lines, the expression was significantly higher in MDA-MB-231. Tumoral expression of Del-1 was also significantly associated with a negative expression of estrogen receptor or progesterone receptor, and low expression of Ki-67, particularly in the case of triple-negative breast cancer (TNBC) (p < 0.036). Furthermore, a correlation was found between Del-1 expression and an aggressive histological grade, nuclear mitosis, and polymorphism, suggesting a possible role in tumor progression. In the survival analysis, a worse distant disease-free survival trend was noted for the group overexpressing Del-1. While all the investigated breast cancer cell lines exhibited Del-1 expression, the expression rate and intensity were specifically prominent in TNBC. In addition, based on its relationship to an unfavorable histology and worse survival trend, Del-1 could act as a molecular target in TNBC patients. © 2018 S. Karger AG, Basel.

DOE Office of Scientific and Technical Information (OSTI.GOV)

Delpassand, M.S.

The power section of a mud driven progressing cavity drill motors consists of a steel rotor shaped with an external helix rotating within a stationary tube with a molded helical elastomeric lining (stator). Operating temperature of the elastomer lining is an important parameter that affects the stator life. Motor operating conditions such as down hole temperature, torque, differential pressure, and speed determine the elastomer temperature. This paper presents an analysis technique to predict stator elastomer temperature as a function of the motor`s operating parameters. A non-linear finite element analysis technique is used to predict the stator temperature. Physical and mechanicalmore » properties of the elastomer are measured, using laboratory equipment such as Monsanto`s RPA2000 dynamic analyzer and BFGoodrich model (II) flexometer. Boundary conditions of the finite element model are defined based on the down hole temperature, differential pressure, and the motor`s speed. Results of the finite element analysis are compared with laboratory test data to verify the accuracy of the analysis.« less

Heat transfer and performance characteristics of axial cooling fans with downstream guide vanes

NASA Astrophysics Data System (ADS)

Terzis, Alexandros; Stylianou, Ioannis; Kalfas, Anestis I.; Ott, Peter

2012-04-01

This study examines experimentally the effect of stators on the performance and heat transfer characteristics of small axial cooling fans. A single fan impeller, followed by nine stator blades in the case of a complete stage, was used for all the experimental configurations. Performance measurements were carried out in a constant speed stage performance test rig while the transient liquid crystal technique was used for the heat transfer measurements. Full surface heat transfer coefficient distributions were obtained by recording the temperature history of liquid crystals on a target plate. The experimental data indicated that the results are highly affected by the flow conditions at the fan outlet. Stators can be beneficial in terms of pressure drop and efficiency, and thus more economical operation, as well as, in the local heat transfer distribution at the wake of the stator blades if the fan is installed very close to the cooling object. However, as the separation distance increases, enhanced heat transfer rate in the order of 25% is observed in the case of the fan impeller.

Improvement of thermal radiation characteristic of AC servomotor using Al-CNT composite material

NASA Astrophysics Data System (ADS)

Kikuchi, Y.; Wakiwaka, H.; Yanagihara, M.

2018-02-01

This study deals with a high thermal conductivity material of aluminum-carbon nanotube (CNT) composite with carbon fiber (CF) and the high radiation performance of AC servomotor using a stator made of nanotube composite material. The composite fabrication process was performed by melting a mixture of granular aluminum of less than 200 μm and CNT under conditions of pressed atmosphere at the same time. Two kinds of motors made using aluminum and the composite were evaluated to confirm the effect of thermal conductivity as the motor stator. A test rod of the composite with 14 wt% CF-7 wt% CNT-aluminum indicated the excellent thermal conductivity of 169 W/(mK) in the radial direction and 173 W/(mK) in the lengthwise direction. According to the obtained temperature radiation characteristic of the AC servomotor, the composite stator using CNT decreased the consumption energy to 16% compared to the conventional one. As a result, the highly efficient motor improved the radiation characteristic using the CNT composite stator.

Core compressor exit stage study, volume 6

NASA Technical Reports Server (NTRS)

Wisler, D. C.

1981-01-01

Rear stage blading designs that have lower losses in their endwall boundary layer regions were studied. A baseline Stage A was designed as a low-speed model of stage 7 of a 10-stage compressor. Candidate rotors and stators were designed which have the potential of reducing endwall losses relative to the baseline. Rotor B uses a type of meanline in the tip region that unloads the leading edge and loads the trailing edge relative to the baseline rotor A designs. Rotor C incorporates a more skewed (hub strong) radial distribution of total pressure and smoother distribution of static pressure on the rotor tip than those of rotor B. Candidate stator B embodies twist gradients in the endwall region. Stator C embodies airfoil sections near the endwalls that have reduced trailing edge loading relative to stator A. The baseline and candidate bladings were tested using four identical stages to produce a true multistage environment. Single-stage tests were also conducted. The test data were analyzed and performances were compared. Several of the candidate configurations showed a performance improvement relative to the baseline.

Flow Instabilities in Feather Seals due to Upstream Harmonic Pressure Fluctuations

NASA Technical Reports Server (NTRS)

Deng, D.; Braun, M. J.; Henricks, Robert C.

2008-01-01

Feather seals (also called slot seals) typically found in turbine stators limit leakage from the platform into the core cavities and from the shroud to the case. They are of various geometric shapes, yet all are contoured to fit the aerodynamic shape of the stator and placed as close as thermomechanically reasonable the powerstream flow passage. Oscillations engendered in the compressor or combustor alter the steady leakage characteristics of these sealing elements and in some instances generate flow instabilities downstream of the seal interface. In this study, a generic feather seal geometry was studied numerically by imposing an upstream harmonic pressure disturbance on the simulated stator-blade gap. The flow and thermal characteristics were determined; it was found that for high pressure drops, large fluctuations in flows in the downstream blade-stator gap can occur. These leakages and pulsations in themselves are not all that significant, yet if coupled with cavity parameters, they could set up resonance events. Computationally generated time-dependent flow fields are captured in sequence video streaming.

Design and experiments of a linear piezoelectric motor driven by a single mode.

PubMed

Liu, Zhen; Yao, Zhiyuan; Li, Xiang; Fu, Qianwei

2016-11-01

In this contribution, we propose a novel linear piezoelectric motor with a compact stator that is driven by a single mode. The linear piezoelectric motor can realize bidirectional motion by changing the vibration modes of the stator. Finite element analysis is performed to determine the required vibration mode of the stator and obtain the optimal stator structure and dimensions. Furthermore, the trajectories of the driving foot are analyzed with and without consideration of the mechanical contact with the slider. It is shown that the trajectory of the driving foot is an oblique line when disregarding the contact, and the trajectory becomes an oblique ellipse while taking into account the contact. Finally, a prototype of the motor is fabricated based on the results of finite element analysis. The optimization results show that the motor reaches its maximum thrust force of 4.0 kg, maximum thrust-weight ratio of 33.3, maximum unloaded velocity of 385 mm/s under the excitation of Mode-B, and maximum unloaded velocity of 315 mm/s under the excitation of Mode-L.

Control Code for Bearingless Switched-Reluctance Motor

NASA Technical Reports Server (NTRS)

Morrison, Carlos R.

2007-01-01

A computer program has been devised for controlling a machine that is an integral combination of magnetic bearings and a switched-reluctance motor. The motor contains an eight-pole stator and a hybrid rotor, which has both (1) a circular lamination stack for levitation and (2) a six-pole lamination stack for rotation. The program computes drive and levitation currents for the stator windings with real-time feedback control. During normal operation, two of the four pairs of opposing stator poles (each pair at right angles to the other pair) levitate the rotor. The remaining two pairs of stator poles exert torque on the six-pole rotor lamination stack to produce rotation. This version is executable in a control-loop time of 40 s on a Pentium (or equivalent) processor that operates at a clock speed of 400 MHz. The program can be expanded, by addition of logic blocks, to enable control of position along additional axes. The code enables adjustment of operational parameters (e.g., motor speed and stiffness, and damping parameters of magnetic bearings) through computer keyboard key presses.

Micro grid control strategy of DFIG unit based on improved DC grid connected topology

NASA Astrophysics Data System (ADS)

Zongze, Xia; Fei, Xia; Zhixiong, Yang

2017-05-01

Aiming to the application of the DFIG connected to DC-Microgrids, an improved topology for the DFIG connected to DC-Microgrids is taken into account in this thesis. The stator side loses the support of voltage and frequency of AC point of common coupling bus. A novel control method suitable to the stator side converter (SSC) and the rotor side converter (RSC) of the topology is proposed. The independent control of stator voltage and frequency, the decoupled control of power and variable speed constant frequency of DFIG are achieved in the doubly-fed induction generator connected to DC-Microgrids. which can enhance the capacity of active power transmission of DFIG during the voltage variation.

Micro-beam friction liner and method of transferring energy

DOEpatents

Mentesana, Charles [Leawood, KS

2007-07-17

A micro-beam friction liner adapted to increase performance and efficiency and reduce wear in a piezoelectric motor or actuator or other device using a traveling or standing wave to transfer energy in the form of torque and momentum. The micro-beam friction liner comprises a dense array of micro-beam projections having first ends fixed relative to a rotor and second ends projecting substantially toward a plurality of teeth of a stator, wherein the micro-beam projections are compressed and bent during piezoelectric movement of the stator teeth, thereby storing the energy, and then react against the stator teeth to convert the stored energy stored to rotational energy in the rotor.

Forensic applicability of multi-allelic InDels with mononucleotide homopolymer structures.

PubMed

Zhang, Shu; Zhu, Qiang; Chen, Xiaogang; Zhao, Yuancun; Zhao, Xiaohong; Yang, Yiwen; Gao, Zehua; Fang, Ting; Wang, Yufang; Zhang, Ji

2018-04-27

Insertion/deletion polymorphisms (InDels), which possess the characteristics of low mutation rates and a short amplicon size, have been regarded as promising markers for forensic DNA analysis. InDels can be classified as bi-allelic or multi-allelic, depending on the number of alleles. Many studies have explored the use of bi-allelic InDels in forensic applications, such as individual identification and ancestry inference. However, multi-allelic InDels have received relatively little attention. In this study, InDels with 2-6 alleles and a minor allele frequency ≥0.01, in Chinese Southern Han (CHS), were retrieved from the 1000 Genomes Project Phase III. Based on the structural analysis of all retrieved InDels, 17 multi-allelic markers with mononucleotide homopolymer structures were selected and combined in one multiplex PCR reaction system. Sensitivity, species specificity and applicability in forensic case work of the multiplex were analyzed. A total of 218 unrelated individuals from a Chinese Han population were genotyped. The combined discriminatory power (CDP), the combined match probability (CMP) and the cumulative probability of exclusion (CPE) were 0.9999999999609, 3.91E-13 and 0.9956, respectively. The results demonstrated that this InDel multiplex panel was highly informative in the investigated population and most of the 26 populations of the 1000 Genomes Project. The data also suggested that multi-allelic InDel markers with monomeric base pair expansions are useful for forensic applications. This article is protected by copyright. All rights reserved. This article is protected by copyright. All rights reserved.

Low-Cost, Rugged High-Vacuum System

NASA Technical Reports Server (NTRS)

Sorensen, Paul; Kline-Schoder, Robert

2012-01-01

A need exists for miniaturized, rugged, low-cost high-vacuum systems. Recent advances in sensor technology have led to the development of very small mass spectrometer detectors as well as other analytical instruments such as scanning electron microscopes. However, the vacuum systems to support these sensors remain large, heavy, and power-hungry. To meet this need, a miniaturized vacuum system was developed based on a very small, rugged, and inexpensive-to-manufacture molecular drag pump (MDP). The MDP is enabled by a miniature, very-high-speed (200,000 rpm), rugged, low-power, brushless DC motor optimized for wide temperature operation and long life. The key advantages of the pump are reduced cost and improved ruggedness compared to other mechanical hig-hvacuum pumps. The machining of the rotor and stators is very simple compared to that necessary to fabricate rotor and stator blades for other pump designs. Also, the symmetry of the rotor is such that dynamic balancing of the rotor will likely not be necessary. Finally, the number of parts in the unit is cut by nearly a factor of three over competing designs. The new pump forms the heart of a complete vacuum system optimized to support analytical instruments in terrestrial applications and on spacecraft and planetary landers. The MDP achieves high vacuum coupled to a ruggedized diaphragm rough pump. Instead of the relatively complicated rotor and stator blades used in turbomolecular pumps, the rotor in the MDP consists of a simple, smooth cylinder of aluminum. This will turn at approximately 200,000 rpm inside an outer stator housing. The pump stator comprises a cylindrical aluminum housing with one or more specially designed grooves that serve as flow channels. To minimize the length of the pump, the gas is forced down the flow channels of the outer stator to the base of the pump. The gas is then turned and pulled toward the top through a second set of channels cut into an inner stator housing that surrounds the

Actitudes Éticas de los estudiantes y egresados en carrera de medicina con metodologías activas

PubMed Central

Novaes, Maria Rita Carvalho Garbi; Novaes, Luiz Carlos Garcez; Guilhem, Dirce; Stepke, Fernando Lolas; Silveira, Carla Cristina Costa; Komatsu, Ricardo Shoiti; Trindade, Eliane Mendonça Vilar; Guiotti, Murilo Galvão

2010-01-01

El presente estudio tiene por objeto desarrollar un diagnostico de la inserción integrada de la ética en la carrera de medicina brasileña con una metodología de aprendizaje basada en problemas y describir las percepciones de actitudes éticas de los estudiantes y egresados. El diseño metodológico es un estudio de caso, descriptivo y documental, con abordaje cualitativo y cuantitativo. La muestra de esta investigación ha sido constituida por 120 estudiantes y 40 egresados de dos promociones del Curso de Medicina de la ESCS. Este proyecto fue aprobado por el Comité de Ética en Investigación - SES/DF. Los estudiantes y egresados de la ESCS demostraron un buen manejo en el abordaje de los conflictos éticos y respeto a los pacientes. Sin embargo, el análisis de sensibilidad ética mostró una fragilidad en las percepciones y aptitudes inapropiadas de los estudiantes de la carrera de medicina, identificada básicamente en los años iniciales, que necesitan más discusiones sistematizadas sobre los aspectos éticos y bioéticos integrados a las actividades prácticas para estimular y fortalecer la reflexión ética de los estudiantes. PMID:20981242

Rotation of artificial rotor axles in rotary molecular motors

PubMed Central

Baba, Mihori; Iwamoto, Kousuke; Ueno, Hiroshi; Hara, Mayu; Nakanishi, Atsuko; Kishikawa, Jun-ichi; Noji, Hiroyuki; Yokoyama, Ken

2016-01-01

F1- and V1-ATPase are rotary molecular motors that convert chemical energy released upon ATP hydrolysis into torque to rotate a central rotor axle against the surrounding catalytic stator cylinder with high efficiency. How conformational change occurring in the stator is coupled to the rotary motion of the axle is the key unknown in the mechanism of rotary motors. Here, we generated chimeric motor proteins by inserting an exogenous rod protein, FliJ, into the stator ring of F1 or of V1 and tested the rotation properties of these chimeric motors. Both motors showed unidirectional and continuous rotation, despite no obvious homology in amino acid sequence between FliJ and the intrinsic rotor subunit of F1 or V1. These results showed that any residue-specific interactions between the stator and rotor are not a prerequisite for unidirectional rotation of both F1 and V1. The torque of chimeric motors estimated from viscous friction of the rotation probe against medium revealed that whereas the F1-FliJ chimera generates only 10% of WT F1, the V1-FliJ chimera generates torque comparable to that of V1 with the native axle protein that is structurally more similar to FliJ than the native rotor of F1. This suggests that the gross structural mismatch hinders smooth rotation of FliJ accompanied with the stator ring of F1. PMID:27647891

Design and performance analysis of a rotary traveling wave ultrasonic motor with double vibrators.

PubMed

Dong, Zhaopeng; Yang, Ming; Chen, Zhangqi; Xu, Liang; Meng, Fan; Ou, Wenchu

2016-09-01

This paper presents the development of a rotary traveling wave ultrasonic motor, in which a vibrating stator and vibrating rotor are combined in one motor. The stator and rotor are designed as similar structures an elastic body and a piezoelectric ceramic ring. In exciting of the piezoelectric ceramics, the elastic body of the stator and rotor will generate respective traveling waves, which force each other forward in the contact zone. Based on the elliptical rule of particle motion and matching principle of vibration, the design rules of two vibrators are determined. The finite element method is used to design the sizes of vibrators to ensure that they operate in resonance, and the simulation is verified by measuring the vibration with an impedance analyzer. It is found out that to maintain an appropriate contact between the stator and rotor, two vibrators need to be designed with close resonance frequencies, different vibration amplitudes, and be driven by an identical driving frequency. To analyze this innovative contact mechanism, particle velocity synthesis theory and contact force analysis using Hertz contact model are carried out. Finally, a prototype is fabricated and tested to verify the theoretical results. The test results show that the output performance of the motor driven by the two vibrators is significantly improved compared to the motor driven by a sole stator or rotor, which confirms the validity of the double-vibrator motor concept. Copyright © 2016 Elsevier B.V. All rights reserved.

Study of noise sources in a subsonic fan using measured blade pressures and acoustic theory

NASA Technical Reports Server (NTRS)

Hanson, D. B.

1975-01-01

Sources of noise in a 1.4 m (4.6 ft) diameter subsonic tip speed propulsive fan running statically outdoors are studied using a combination of techniques. Signals measured with pressure transducers on a rotor blade are plotted in a format showing the space-time history of inlet distortion. Study of these plots visually and with statistical correlation analysis confirms that the inlet flow contains long, thin eddies of turbulence. Turbulence generated in the boundary layer of the shroud upstream of the rotor tips was not found to be an important noise source. Fan noise is diagnosed by computing narrowband spectra of rotor and stator sound power and comparing these with measured sound power spectra. Rotor noise is computed from spectra of the measured blade pressures and stator noise is computed using the author's stator noise theory. It is concluded that the rotor and stator sources contribute about equally at frequencies in the vicinity of the first three harmonics of blade passing frequency. At higher frequencies, the stator contribution diminishes rapidly and the rotor/inlet turbulence mechanism dominates. Two parametric studies are performed by using the rotor noise calculation procedure which was correlated with test. In the first study, the effects on noise spectrum and directivity are calculated for changes in turbulence properties, rotational Mach number, number of blades, and stagger angle. In the second study the influences of design tip speed and blade number on noise are evaluated.

Design, aerodynamics and autonomy of the DelFly.

PubMed

de Croon, G C H E; Groen, M A; De Wagter, C; Remes, B; Ruijsink, R; van Oudheusden, B W

2012-06-01

One of the major challenges in robotics is to develop a fly-like robot that can autonomously fly around in unknown environments. In this paper, we discuss the current state of the DelFly project, in which we follow a top-down approach to ever smaller and more autonomous ornithopters. The presented findings concerning the design, aerodynamics and autonomy of the DelFly illustrate some of the properties of the top-down approach, which allows the identification and resolution of issues that also play a role at smaller scales. A parametric variation of the wing stiffener layout produced a 5% more power-efficient wing. An experimental aerodynamic investigation revealed that this could be associated with an improved stiffness of the wing, while further providing evidence of the vortex development during the flap cycle. The presented experiments resulted in an improvement in the generated lift, allowing the inclusion of a yaw rate gyro, pressure sensor and microcontroller onboard the DelFly. The autonomy of the DelFly is expanded by achieving (1) an improved turning logic to obtain better vision-based obstacle avoidance performance in environments with varying texture and (2) successful onboard height control based on the pressure sensor.

Mejoras en la exactitud del reloj de ángulo horario del telescopio de 2,15 mts de CASLEO

NASA Astrophysics Data System (ADS)

Aballay, J. L.; Pereyra, P. F.; Marún, A. H.

Para aumentar la exactitud en el control del ángulo horario del telescopio, se está implementando el uso de un reloj con una precisión de 1/100 seg. En conjunto con el encoder que otorga la posición con un acierto de 0,012 seg. de arco, se podrá implementar otro dígito en el reloj de ángulo horario con la posibilidad de ver las décimas. Esto, sumado a la precisión ya lograda en declinación, permitirá realizar offsets con mayor exactitud.

Case Study: del Amo Bioventing

EPA Science Inventory

The attached presentation discusses the fundamentals of bioventing in the vadose zone. The basics of bioventing are presented. The experience to date with the del Amo Superfund Site is presented as a case study.

Permanent magnet energy conversion machine with magnet mounting arrangement

DOEpatents

Hsu, John S.; Adams, Donald J.

1999-01-01

A hybrid permanent magnet dc motor includes three sets of permanent magnets supported by the rotor and three sets of corresponding stators fastened to the surrounding frame. One set of magnets operates across a radial gap with a surrounding radial gap stator, and the other two sets of magnets operate off the respective ends of the rotor across respective axial gaps.

Optimization of a Low Heat Load Turbine Nozzle Guide Vane

DTIC Science & Technology

2006-03-01

HEAT LOAD TURBINE NOZZLE GUIDE VANE THESIS Presented to the Faculty Department of Aeronautical and Astronautical Engineering ...a function of turbine inlet temperature. .................... 2 Figure 2 Traditional turbofan engine and stator vane location (from Ref [1...the non-rotating stator vanes within a cross-section of a classical two-spool turbofan engine which has an inlet, 4 compressor, combustor, turbine

Percepcion de los profesores universitarios acerca del concepto cultura cientifica y de sus implicaciones en el nuevo bachillerato del Recinto de Rio Piedras de la Universidad de Puerto Rico

NASA Astrophysics Data System (ADS)

Ramos Pastrana, Nilsa

El Senado Academico del Recinto de Rio Piedras de la Universidad de Puerto Rico aprobo en el ano academico 2005-2006 la Certificacion 46, que contiene los lineamientos de un nuevo bachillerato. Este nuevo bachillerato introdujo cambios significativos en el curriculo tradicional. Entre ellos se encuentra la reduccion del componente de educacion general y el de Ciencias Biologicas en particular. La reduccion de creditos en el componente de Ciencias Biologicas ha obligado a reevaluar el concepto de cultura cientifica que desarrollan esos cursos. El proposito del estudio consistio en auscultar las percepciones de los profesores de las Facultades de Administracion de Empresas, Humanidades, Ciencias Sociales, Ciencias Naturales, Educacion y Estudios Generales del Recinto de Rio Piedras de la Universidad de Puerto Rico en torno al concepto de cultura cientifica, los contenidos disciplinares del curso de Ciencias Biologicas y la reduccion de creditos en el nuevo bachillerato. Las preguntas que guiaron la investigacion fueron: ¿cuales son las percepciones que tienen los profesores de las Facultades de Administracion de Empresas, Ciencias Sociales, Estudios Generales, Ciencias Naturales, Humanidades y Educacion, en torno al concepto de cultura cientifica y los contenidos disciplinares del curso de Ciencias Biologicas? ¿cuales son las percepciones que tienen los profesores de Ciencias Biologicas en torno al concepto cultura cientifica y los contenidos disciplinares del curso de Ciencias Biologicas? ¿existen diferencias significativas por facultad, genero, experiencia, rango y nombramiento en las percepciones que tienen los profesores del Recinto de Rio Piedras de la Universidad de Puerto Rico sobre los elementos que caracterizan la cultura cientifica y los contenidos biologicos que deben tener los egresados del Recinto? ¿que implicaciones curriculares tienen estos testimonios en el desarrollo del concepto de cultura cientifica en el nuevo bachillerato? Para realizar la

An evaluation of Delaware's DelTrac program : building an integrated transportation management system

DOT National Transportation Integrated Search

2004-06-01

The DelTrac deployment experience included both successes and unmet challenges. Programmatically, the DelTrac approach to managing ITS has been successful at creating a great deal of integration and cooperation between organizations at DelDOT. Stakeh...

Control System for Bearingless Motor-generator

NASA Technical Reports Server (NTRS)

Kascak, Peter E. (Inventor); Jansen, Ralph H. (Inventor); Dever, Timothy P. (Inventor)

2008-01-01

A control system for an electromagnetic rotary drive for bearingless motor-generators comprises a winding configuration comprising a plurality of individual pole pairs through which phase current flows, each phase current producing both a lateral force and a torque. A motor-generator comprises a stator, a rotor supported for movement relative to the stator, and a control system. The motor-generator comprises a winding configuration supported by the stator. The winding configuration comprises at least three pole pairs through which phase current flows resulting in three three-phase systems. Each phase system has a first rotor reference frame axis current that produces a levitating force with no average torque and a second rotor reference frame axis current that produces torque.

Special-Purpose High-Torque Permanent-Magnet Motors

NASA Technical Reports Server (NTRS)

Doane, George B., III

1995-01-01

Permanent-magnet brushless motors that must provide high commanded torques and satisfy unusual heat-removal requirement are developed. Intended for use as thrust-vector-control actuators in large rocket engines. Techniques and concepts used to design improved motors for special terrestrial applications. Conceptual motor design calls for use of rotor containing latest high-energy-product rare-earth permanent magnets so that motor produces required torque while drawing smallest possible currents from power supply. Torque generated by electromagnetic interaction between stator and permanent magnets in rotor when associated electronic circuits applied appropriately temporally and spatially phased currents to stator windings. Phase relationships needed to produce commanded torque computed in response to torque command and to electronically sensed angular position of rotor relative to stator.

Electrode geometry for electrostatic generators and motors

DOEpatents

Post, Richard F.

2016-02-23

An electrostatic (ES) device is described with electrodes that improve its performance metrics. Devices include ES generators and ES motors, which are comprised of one or more stators (stationary members) and one or more rotors (rotatable members). The stator and rotors are configured as a pair of concentric cylindrical structures and aligned about a common axis. The stator and rotor are comprised of an ensemble of discrete, longitudinal electrodes, which are axially oriented in an annular arrangement. The shape of the electrodes described herein enables the ES device to function at voltages significantly greater than that of the existing art, resulting in devices with greater power-handling capability and overall efficiency. Electrode shapes include, but are not limited to, rods, corrugated sheets and emulations thereof.

Effects of interstage diffuser flow distortion on the performance of a 15.41-centimeter tip diameter axial power turbine

NASA Technical Reports Server (NTRS)

Mclallin, K. L.; Kofskey, M. G.; Civinskas, K. C.

1983-01-01

The performance of a variable-area stator, axial flow power turbine was determined in a cold-air component research rig for two inlet duct configurations. The two ducts were an interstage diffuser duct and an accelerated-flow inlet duct which produced stator inlet boundary layer flow blockages of 11 percent and 3 percent, respectively. Turbine blade total efficiency at design point was measured to be 5.3 percent greater with the accelerated-flow inlet duct installed due to the reduction in inlet blockage. Blade component measurements show that of this performance improvement, 35 percent occurred in the stator and 65 percent occurred in the rotor. Analysis of inlet duct internal flow using an Axisymmetric Diffuser Duct Code (ADD Code) were in substantial agreement with the test data.

Wind turbine generators having wind assisted cooling systems and cooling methods

DOEpatents

Bagepalli, Bharat [Niskayuna, NY; Barnes, Gary R [Delanson, NY; Gadre, Aniruddha D [Rexford, NY; Jansen, Patrick L [Scotia, NY; Bouchard, Jr., Charles G.; Jarczynski, Emil D [Scotia, NY; Garg, Jivtesh [Cambridge, MA

2008-09-23

A wind generator includes: a nacelle; a hub carried by the nacelle and including at least a pair of wind turbine blades; and an electricity producing generator including a stator and a rotor carried by the nacelle. The rotor is connected to the hub and rotatable in response to wind acting on the blades to rotate the rotor relative to the stator to generate electricity. A cooling system is carried by the nacelle and includes at least one ambient air inlet port opening through a surface of the nacelle downstream of the hub and blades, and a duct for flowing air from the inlet port in a generally upstream direction toward the hub and in cooling relation to the stator.

Design of a Modular E-Core Flux Concentrating Axial Flux Machine

DOE Office of Scientific and Technical Information (OSTI.GOV)

Husain, Tausif; Sozer, Yilmaz; Husain, Iqbal

2015-09-02

In this paper a novel E-Core axial flux machine is proposed. The machine has a double stator-single rotor configuration with flux concentrating ferrite magnets, and pole windings across each leg of an E-Core stator. E-Core stators with the proposed flux-concentrating rotor arrangement result in better magnet utilization and higher torque density. The machine also has a modular structure facilitating simpler construction. This paper presents a single phase and a three-phase version of the E-Core machine. Case study for a 1.1 kW, 400 rpm machine for both the single phase and three-phase axial flux machine is presented. The results are verifiedmore » through 3D finite element analysis.« less

An evaluation of some alternative approaches for reducing fan tone noise

NASA Astrophysics Data System (ADS)

Dittmar, James H.; Woodward, Richard P.

1992-02-01

The potential of two alternative approaches for reducing fan ton noise was investigated in this study. One of these approaches increases the number of rotor blades to shift the tone noise to higher frequencies that are not rated as strongly by the perceived noise scale. This alternative fan also would have a small number of long chord stator vanes which would reduce the stator response and lower rotor-stator interaction noise. Comparison of the conventional and alternative fan concepts showed that this alternative approach has as large or larger a perceived tone noise reduction potential as the conventional approach. The other alternative, a high Mach number inlet, is evaluated both for its noise attenuation and for its change in noise directivity.

Hybrid-secondary uncluttered induction machine

DOEpatents

Hsu, John S.

2001-01-01

An uncluttered secondary induction machine (100) includes an uncluttered rotating transformer (66) which is mounted on the same shaft as the rotor (73) of the induction machine. Current in the rotor (73) is electrically connected to current in the rotor winding (67) of the transformer, which is not electrically connected to, but is magnetically coupled to, a stator secondary winding (40). The stator secondary winding (40) is alternately connected to an effective resistance (41), an AC source inverter (42) or a magnetic switch (43) to provide a cost effective slip-energy-controlled, adjustable speed, induction motor that operates over a wide speed range from below synchronous speed to above synchronous speed based on the AC line frequency fed to the stator.

On the Use of Surface Porosity to Reduce Unsteady Lift

NASA Technical Reports Server (NTRS)

Tinetti, Ana F.; Kelly, Jeffrey J.; Bauer, Steven X. S.; Thomas, Russell H.

2001-01-01

An innovative application of existing technology is proposed for attenuating the effects of transient phenomena, such as rotor-stator and rotor-strut interactions, linked to noise and fatigue failure in turbomachinery environments. A computational study was designed to assess the potential of passive porosity technology as a mechanism for alleviating interaction effects by reducing the unsteady lift developed on a stator airfoil subject to wake impingement. The study involved a typical high bypass fan Stator airfoil (solid baseline and several porous configurations), immersed in a free field and exposed to the effects of a transversely moving wake. It was found that, for the airfoil under consideration, the magnitude of the unsteady lift could be reduced more than 18% without incurring significant performance losses.

Three-degree-of-freedom ultrasonic motor using a 5-mm-diameter piezoelectric ceramic tube.

PubMed

Mingsen Guo; Junhui Hu; Hua Zhu; Chunsheng Zhao; Shuxiang Dong

2013-07-01

A small three-degree-of-freedom ultrasonic motor has been developed using a simple piezoelectric lead zirconate titanate (PZT)-tube stator (OD 5 mm, ID 3 mm, length 15 mm). The stator drives a ball-rotor into rotational motion around one of three orthogonal (x-, y-, and z-) axes by combing the first longitudinal and second bending vibration modes. A motor prototype was fabricated and characterized; its performance was superior to those of previous motors made with a PZT ceramic/metal composite stator of comparable size. The method for further improving the performance was discussed. The motor can be further miniaturized and it has potential to be applied to medical microrobots, endoscopes or micro laparoscopic devices, and cell manipulation devices.

Control system for bearingless motor-generator

NASA Technical Reports Server (NTRS)

Jansen, Ralph H. (Inventor); Dever, Timothy P. (Inventor); Kascak, Peter E. (Inventor)

2010-01-01

A control system for an electromagnetic rotary drive for bearingless motor-generators comprises a winding configuration comprising a plurality of individual pole pairs through which phase current flows, each phase current producing both a lateral force and a torque. A motor-generator comprises a stator, a rotor supported for movement relative to the stator, and a control system. The motor-generator comprises a winding configuration supported by the stator. The winding configuration comprises at least three pole pairs through which phase current flows resulting in three three-phase systems. Each phase system has a first rotor reference frame axis current that produces a levitating force with no average torque and a second rotor reference frame axis current that produces torque.

Fixture for aligning motor assembly

DOEpatents

Shervington, Roger M.; Vaghani, Vallabh V.; Vanek, Laurence D.; Christensen, Scott A.

2009-12-08

An alignment fixture includes a rotor fixture, a stator fixture and a sensor system which measures a rotational displacement therebetween. The fixture precisely measures rotation of a generator stator assembly away from a NULL position referenced by a unique reference spline on the rotor shaft. By providing an adjustable location of the stator assembly within the housing, the magnetic axes within each generator shall be aligned to a predetermined and controlled tolerance between the generator interface mounting pin and the reference spline on the rotor shaft. Once magnetically aligned, each generator is essentially a line replaceable unit which may be readily mounted to any input of a multi-generator gearbox assembly with the assurance that the magnetic alignment will be within a predetermined tolerance.

El uso de la neuromodulación para el tratamiento del temblor

PubMed Central

Bendersky, Damián; Ajler, Pablo; Yampolsky, Claudio

2014-01-01

Introducción: El temblor puede ser un desorden incapacitante y el tratamiento de primera línea para estos pacientes es farmacológico. Sin embargo, este tratamiento puede llevar a una reducción satisfactoria del temblor en sólo el 50% de los pacientes con temblor esencial. La talamotomía era el tratamiento de elección para el temblor refractario al tratamiento médico hasta que comenzó a utilizarse la estimulación cerebral profunda (ECP) del núcleo ventral intermedio (Vim) del tálamo. En la actualidad, raramente se realiza la talamotomía. Métodos: Este artículo es una revisión no sistemática de las indicaciones, resultados, parámetros de programación y técnica quirúrgica de la ECP del Vim para el tratamiento del temblor. Resultados: Aunque los resultados clínicos son similares usando la talamotomía o la ECP del Vim, la primera causa más efectos adversos que la última. Además, la ECP puede ser usada bilateralmente, mientras que la talamotomía tiene un alto riesgo de causar disartria cuando se realiza de ambos lados. La ECP del Vim logró una adecuada mejoría del temblor en varias series de pacientes con temblor causado por temblor esencial, enfermedad de Parkinson o esclerosis múltiple. Además del Vim, hay otros blancos que están siendo usados por varios autores, tales como la zona incerta y las radiaciones prelemniscales. Conclusión: La ECP del Vim es un tratamiento útil para el temblor incapacitante refractario al tratamiento médico. Es esencial realizar una precisa selección de pacientes, así como utilizar una técnica quirúrgica correcta. Aún se desconoce el mejor blanco estereotáctico para el temblor, aunque el Vim es el más usado. PMID:25165613

CHEK2 1100delC and male breast cancer in the Netherlands.

PubMed

Wasielewski, Marijke; den Bakker, Michael A; van den Ouweland, Ans; Meijer-van Gelder, Marion E; Portengen, Henk; Klijn, Jan G M; Meijers-Heijboer, Hanne; Foekens, John A; Schutte, Mieke

2009-07-01

Mutations in the breast cancer susceptibility genes BRCA1, BRCA2, and CHEK2 are known risk factors for female breast cancer. Mutations in BRCA1 and BRCA2 also are associated with male breast cancer (MBC). Similarly, it had been suggested in the original CHEK2 identification report that the CHEK2 1100delC mutation confers an increased risk for MBC. Here, we have evaluated the risk of CHEK2 1100delC for MBC by genotyping CHEK2 1100delC in 23 familial and 71 unselected Dutch MBC cases. None of the 23 familial MBC cases carried the CHEK2 1100delC mutation. In contrast, CHEK2 1100delC was present in 3 of the 71 (4.2%) unselected MBC cases, which was significantly more prevalent than the 1.1% Dutch population frequency assessed in 1,692 individuals (P = 0.05, OR = 4.1, 95% CI 1.2-14.3). Our data suggest that, in the Netherlands, CHEK2 1100delC is associated with an increased risk for MBC.

Field measurements of del13C in ecosystem respiration

NASA Astrophysics Data System (ADS)

van Asperen, Hella; Sabbatini, Simone; Nicolini, Giacomo; Warneke, Thorsten; Papale, Dario; Notholt, Justus

2014-05-01

Stable carbon isotope del13C-measurements are extensively used to study ecological and biogeochemical processes in ecosystems. Above terrestrial ecosystems, atmospheric del13C can vary largely due to photosynthetic fractionation. Photosynthetic processes prefer the uptake of the lighter isotope 12C (in CO2), thereby enriching the atmosphere in 13C and depleting the ecosystem carbon. At night, when ecosystem respiratory fluxes are dominant, 13C-depleted CO2 is respired and thereby depletes the atmospheric del13C-content. Different ecosystems and different parts of one ecosystem (type of plant, leaves, and roots) fractionate and respire with a different del13C-ratio signature. By determining the del13C-signature of ecosystem respiration in temporal and spatial scale, an analysis can be made of the composition of respiratory sources of the ecosystem. A field study at a dry cropland after harvest (province of Viterbo, Lazio, Italy) was performed in the summer of 2013. A FTIR (Fourier Transform Infrared Spectrometer) was set up to continuously measure CO2-, CH4-, N2O-, CO- and del13C-concentrations. The FTIR was connected to 2 different flux measurements systems: a Flux Gradient system (sampling every half hour at 1.3m and 4.2m) and 2 flux chambers (measured every hour), providing a continuous data set of the biosphere-atmosphere gas fluxes and of the gas concentrations at different heights. Keeling plot intercept values of respiratory CO2, measured by the Flux Gradient system at night, were determined to be between -25‰ and -20‰. Keeling plot intercept values of respiratory CO2, measured by the flux chamber system, varied between -24‰ and -29‰, and showed a clear diurnal pattern, suggesting different (dominant) respiratory processes between day and night.

[Strengths and future of the Revista Médica del Instituto Mexicano del Seguro Social].

PubMed

Fajardo-Dolci, Germán

2014-01-01

The journals of medicine arose as a communication tool more than 200 years ago. At the beginning, their nature was local; later, their aim was to spread medical information along the nation; and, finally, they sought to reach the world distribution. The Revista Médica del Instituto Mexicano del Seguro Social was published for the first time 52 years ago, and it has walked its way from local to international distribution. This journal has 23 000 subscribers, it is included in Medline and it reached a 0.112 SCImago Journal Rank in 2012. Its website receives around 200 000 visits monthly and 45 % are foreign visits. In the future, the peer review system is going to be strengthened, and the journal is going to offer audio, video, and applications to reinforce interactive participation between authors, readers in order to reach modernity and draw young new attention.

Combined passive bearing element/generator motor

DOEpatents

Post, Richard F.

2000-01-01

An electric machine includes a cylindrical rotor made up of an array of permanent magnets that provide a N-pole magnetic field of even order (where N=4, 6, 8, etc.). This array of permanent magnets has bars of identical permanent magnets made of dipole elements where the bars are assembled in a circle. A stator inserted down the axis of the dipole field is made of two sets of windings that are electrically orthogonal to each other, where one set of windings provides stabilization of the stator and the other set of windings couples to the array of permanent magnets and acts as the windings of a generator/motor. The rotor and the stator are horizontally disposed, and the rotor is on the outside of said stator. The electric machine may also include two rings of ferromagnetic material. One of these rings would be located at each end of the rotor. Two levitator pole assemblies are attached to a support member that is external to the electric machine. These levitator pole assemblies interact attractively with the rings of ferromagnetic material to produce a levitating force upon the rotor.

Laser anemometer measurements and computations in an annular cascade of high turning core turbine vanes

NASA Technical Reports Server (NTRS)

Goldman, Louis J.; Seasholtz, Richard G.

1992-01-01

An advanced laser anemometer (LA) was used to measure the axial and tangential velocity components in an annular cascade of turbine stator vanes designed for a high bypass ratio engine. These vanes were based on a redesign of the first-stage stator, of a two-stage turbine, that produced 75 degrees of flow turning. Tests were conducted on a 0.771 scale model of the engine size stator. The advanced LA fringe system was designed to employ thinner than usual laser beams resulting in a 50-micron-diameter probe volume. Window correction optics were used to ensure that the laser beams did not uncross in passing through the curved optical access port. Experimental LA measurements of velocity and turbulence were obtained both upstream, within, and downstream of the stator vane row at the design exit critical velocity ratio of 0.896 at the hub. Static pressures were also measured on the vane surface. The measurements are compared, where possible with calculations from a 3-D inviscid flow analysis. The data are presented in both graphic and tabulated form so that they may be readily used to compare against other turbomachinery computations.

Fan Noise Source Diagnostic Test: Tone Modal Structure Results

NASA Technical Reports Server (NTRS)

Heidelberg, Laurence J.

2002-01-01

This investigation is part of a test series that was extremely comprehensive and included aerodynamic and acoustic testing of a fan stage using two different fan rotors and three different stator designs. The test series is known as the Source Diagnostic Test (SDT) and was conducted by NASA Glenn as part of the Advanced Subsonic Technology (AST) Noise Reduction Program. Tone mode measurements of one of the rotors with three different stators were made. The stator designs involve changes in vane count and sweep at constant solidity. The results of both inlet and exhaust tone mode measurements are presented in terms of mode power for both circumferential and radial mode orders. The results show benefits of vane sweep to be large, up to 13 dB in total tone power. At many conditions, the increase in power due to cutting on the rotor/stator interaction is more than offset by vane sweep. The rotor locked mode is shown as an important contributor to tone power when the blade tip speed is near and above Mach one. This is most evident in the inlet when the direct rotor field starts to cut on.

Rotary blood pump

NASA Technical Reports Server (NTRS)

Benkowski, Robert J. (Inventor); Kiris, Cetin (Inventor); Kwak, Dochan (Inventor); Rosenbaum, Bernard J. (Inventor); Bacak, James W. (Inventor); DeBakey, Michael E. (Inventor)

1999-01-01

A blood pump that comprises a pump housing having a blood flow path therethrough, a blood inlet, and a blood outlet; a stator mounted to the pump housing, the stator having a stator field winding for producing a stator magnetic field; a flow straightener located within the pump housing, and comprising a flow straightener hub and at least one flow straightener blade attached to the flow straightener hub; a rotor mounted within the pump housing for rotation in response to the stator magnetic field, the rotor comprising an inducer and an impeller; the inducer being located downstream of the flow straightener, and comprising an inducer hub and at least one inducer blade attached to the inducer hub; the impeller being located downstream of the inducer, and comprising an impeller hub and at least one impeller blade attached to the impeller hub; and preferably also comprising a diffuser downstream of the impeller, the diffuser comprising a diffuser hub and at least one diffuser blade. Blood flow stagnation and clot formation within the pump are minimized by, among other things, providing the inducer hub with a diameter greater than the diameter of the flow straightener hub; by optimizing the axial spacing between the flow straightener hub and the inducer hub, and between the impeller hub and the diffuser hub; by optimizing the inlet angle of the diffuser blades; and by providing fillets or curved transitions between the upstream end of the inducer hub and the shaft mounted therein, and between the impeller hub and the shaft mounted therein.

Self-Centering Reciprocating-Permanent-Magnet Machine

NASA Technical Reports Server (NTRS)

Bhate, Suresh; Vitale, Nick

1988-01-01

New design for monocoil reciprocating-permanent-magnet electric machine provides self-centering force. Linear permanent-magnet electrical motor includes outer stator, inner stator, and permanent-magnet plunger oscillateing axially between extreme left and right positions. Magnets arranged to produce centering force and allows use of only one coil of arbitrary axial length. Axial length of coil chosen to provide required efficiency and power output.

Turbine vane segment and impingement insert configuration for fail-safe impingement insert retention

DOEpatents

Burdgick, Steven Sebastian; Kellock, Iain Robertson

2003-05-13

An impingement insert sleeve is provided that is adapted to be disposed in a coolant cavity defined through a stator vane. The insert has a generally open inlet end and first and second pairs of diametrically opposed side walls, and at least one fail-safe tab defined at a longitudinal end of the insert for limiting radial displacement of the insert with respect to the stator vane.

Removable bearing arrangement for a wind turbine generator

DOEpatents

Bagepalli, Bharat Sampathkumaran; Jansen, Patrick Lee; Gadre, Aniruddha Dattatraya

2010-06-15

A wind generator having removable change-out bearings includes a rotor and a stator, locking bolts configured to lock the rotor and stator, a removable bearing sub-assembly having at least one shrunk-on bearing installed, and removable mounting bolts configured to engage the bearing sub-assembly and to allow the removable bearing sub-assembly to be removed when the removable mounting bolts are removed.

Method for changing removable bearing for a wind turbine generator

DOEpatents

Bagepalli, Bharat Sampathkumaran [Niskayuna, NY; Jansen, Patrick Lee , Gadre; Dattatraya, Aniruddha [Rexford, NY

2008-04-22

A wind generator having removable change-out bearings includes a rotor and a stator, locking bolts configured to lock the rotor and stator, a removable bearing sub-assembly having at least one shrunk-on bearing installed, and removable mounting bolts configured to engage the bearing sub-assembly and to allow the removable bearing sub-assembly to be removed when the removable mounting bolts are removed.

Analysis of the NASA White Sands Test Facility (WSTF) Test System for Friction-Ignition of Metallic Materials

NASA Technical Reports Server (NTRS)

Shoffstall, Michael S.; Wilson, D. Bruce; Stoltzfus, Joel M.

2000-01-01

Friction is a known ignition source for metals in oxygen-enriched atmospheres. The test system developed by the NASA White Sands Test Facility in response to ASTM G-94 has been used successfully to determine the relative ignition from friction of numerous metallic materials and metallic materials pairs. These results have been ranked in terms of a pressure-velocity product (PV) as measured under the prescribed test conditions. A high value of 4.1(exp 8) watts per square meter for Inconel MA 754 is used to imply resistance to friction ignition, whereas a low value of 1.04(exp 8) watts per square meter for stainless steel 304 is taken as indicating material susceptible to friction ignition. No attempt has been made to relate PV values to other material properties. This work reports the analysis of the WSTF friction-ignition test system for producing fundamental properties of metallic materials relating to ignition through friction. Three materials, aluminum, titanium, and nickel were tested in the WSTF frictional ignition instrument system under atmospheres of oxygen or nitrogen. Test conditions were modified to reach a steady state of operation, that is applied, the force was reduced and the rotational speed was reduced. Additional temperature measurements were made on the stator sample. The aluminum immediately galled on contact (reproducible) and the test was stopped. Titanium immediately ignited as a result of non-uniform contact of the stator and rotor. This was reproducible. A portion of the stator sampled burned, but the test continued. Temperature measurements on the stator were used to validate the mathematical model used for estimating the interface (stator/rotor) temperature. These interface temperature measurements and the associate thermal flux into the stator were used to distinguish material-phase transitions, chemical reaction, and mechanical work. The mechanical work was used to analyze surface asperities in the materials and to estimate a

Improved Electromagnetic Brake

NASA Technical Reports Server (NTRS)

Martin, Toby B.

2004-01-01

A proposed design for an electromagnetic brake would increase the reliability while reducing the number of parts and the weight, relative to a prior commercially available electromagnetic brake. The reductions of weight and the number of parts could also lead to a reduction of cost. A description of the commercial brake is prerequisite to a description of the proposed electromagnetic brake. The commercial brake (see upper part of figure) includes (1) a permanent magnet and an electromagnet coil on a stator and (2) a rotor that includes a steel contact plate mounted, with tension spring loading, on an aluminum hub. The stator is mounted securely on a stationary object, which would ordinarily be the housing of a gear drive or a motor. The rotor is mounted on the shaft of the gear drive or motor. The commercial brake nominally operates in a fail-safe (in the sense of normally braking) mode: In the absence of current in the electromagnet coil, the permanent magnet pulls the contact plate, against the spring tension, into contact with the stator. To release the brake, one excites the electromagnet with a current of the magnitude and polarity chosen to cancel the magnetic flux of the permanent magnet, thereby enabling the spring tension to pull the contact plate out of contact with the stator. The fail-safe operation of the commercial brake depends on careful mounting of the rotor in relation to the stator. The rotor/stator gap must be set with a tolerance between 10 and 15 mils (between about 0.25 and about 0.38 mm). If the gap or the contact pad is thicker than the maximum allowable value, then the permanent magnetic field will not be strong enough to pull the steel plate across the gap. (For this reason, any contact pad between the contact plate and the stator must also be correspondingly thin.) If the gap exceeds the maximum allowable value because of shaft end play, it becomes impossible to set the brake by turning off the electromagnet current. Although it may

Turbofan noise generation. Volume 2: Computer programs

NASA Technical Reports Server (NTRS)

Ventres, C. S.; Theobald, M. A.; Mark, W. D.

1982-01-01

The use of a package of computer programs developed to calculate the in duct acoustic mods excited by a fan/stator stage operating at subsonic tip speed is described. The following three noise source mechanisms are included: (1) sound generated by the rotor blades interacting with turbulence ingested into, or generated within, the inlet duct; (2) sound generated by the stator vanes interacting with the turbulent wakes of the rotor blades; and (3) sound generated by the stator vanes interacting with the velocity deficits in the mean wakes of the rotor blades. The computations for three different noise mechanisms are coded as three separate computer program packages. The computer codes are described by means of block diagrams, tables of data and variables, and example program executions; FORTRAN listings are included.

Acoustic Performance of Novel Fan Noise Reduction Technologies for a High Bypass Model Turbofan at Simulated Flights Conditions

NASA Technical Reports Server (NTRS)

Elliott, David M.; Woodward, Richard P.; Podboy, Gary G.

2010-01-01

Two novel fan noise reduction technologies, over the rotor acoustic treatment and soft stator vane technologies, were tested in an ultra-high bypass ratio turbofan model in the NASA Glenn Research Center s 9- by 15-Foot Low-Speed Wind Tunnel. The performance of these technologies was compared to that of the baseline fan configuration, which did not have these technologies. Sideline acoustic data and hot film flow data were acquired and are used to determine the effectiveness of the various treatments. The material used for the over the rotor treatment was foam metal and two different types were used. The soft stator vanes had several internal cavities tuned to target certain frequencies. In order to accommodate the cavities it was necessary to use a cut-on stator to demonstrate the soft vane concept.

Engine dynamic analysis with general nonlinear finite element codes. II - Bearing element implementation, overall numerical characteristics and benchmarking

NASA Technical Reports Server (NTRS)

Padovan, J.; Adams, M.; Lam, P.; Fertis, D.; Zeid, I.

1982-01-01

Second-year efforts within a three-year study to develop and extend finite element (FE) methodology to efficiently handle the transient/steady state response of rotor-bearing-stator structure associated with gas turbine engines are outlined. The two main areas aim at (1) implanting the squeeze film damper element into a general purpose FE code for testing and evaluation; and (2) determining the numerical characteristics of the FE-generated rotor-bearing-stator simulation scheme. The governing FE field equations are set out and the solution methodology is presented. The choice of ADINA as the general-purpose FE code is explained, and the numerical operational characteristics of the direct integration approach of FE-generated rotor-bearing-stator simulations is determined, including benchmarking, comparison of explicit vs. implicit methodologies of direct integration, and demonstration problems.

Reactive power generation in high speed induction machines by continuously occurring space-transients

NASA Astrophysics Data System (ADS)

Laithwaite, E. R.; Kuznetsov, S. B.

1980-09-01

A new technique of continuously generating reactive power from the stator of a brushless induction machine is conceived and tested on a 10-kw linear machine and on 35 and 150 rotary cage motors. An auxiliary magnetic wave traveling at rotor speed is artificially created by the space-transient attributable to the asymmetrical stator winding. At least two distinct windings of different pole-pitch must be incorporated. This rotor wave drifts in and out of phase repeatedly with the stator MMF wave proper and the resulting modulation of the airgap flux is used to generate reactive VA apart from that required for magnetization or leakage flux. The VAR generation effect increases with machine size, and leading power factor operation of the entire machine is viable for large industrial motors and power system induction generators.

Turbofan noise generation. Volume 2: Computer programs

NASA Astrophysics Data System (ADS)

Ventres, C. S.; Theobald, M. A.; Mark, W. D.

1982-07-01

The use of a package of computer programs developed to calculate the in duct acoustic mods excited by a fan/stator stage operating at subsonic tip speed is described. The following three noise source mechanisms are included: (1) sound generated by the rotor blades interacting with turbulence ingested into, or generated within, the inlet duct; (2) sound generated by the stator vanes interacting with the turbulent wakes of the rotor blades; and (3) sound generated by the stator vanes interacting with the velocity deficits in the mean wakes of the rotor blades. The computations for three different noise mechanisms are coded as three separate computer program packages. The computer codes are described by means of block diagrams, tables of data and variables, and example program executions; FORTRAN listings are included.

Pastoral del Nino: Bringing the Abundant Life to Paraguayan Children

ERIC Educational Resources Information Center

Austin, Ann Berghout; Aquino, Cyle; Burro, Elizabeth

2007-01-01

Pastoral del Nino is transforming children's lives in rural Paraguay. Part of Pastoral Social (Catholic Social Services), Pastoral del Nino's primary focus is to bring "vida en abundancia" (the abundant life) to families by ensuring that mothers survive childbirth and children reach their first birthdays. In addition, the organization…

Perk Ablation Ameliorates Myelination in S63del-Charcot–Marie–Tooth 1B Neuropathy

PubMed Central

Musner, Nicolò; Sidoli, Mariapaola; Zambroni, Desireè; Del Carro, Ubaldo; Ungaro, Daniela; D’Antonio, Maurizio; Feltri, Maria L.

2016-01-01

In peripheral nerves, P0 glycoprotein accounts for more than 20% of myelin protein content. P0 is synthesized by Schwann cells, processed in the endoplasmic reticulum (ER) and enters the secretory pathway. However, the mutant P0 with S63 deleted (P0S63del) accumulates in the ER lumen and induces a demyelinating neuropathy in Charcot–Marie–Tooth disease type 1B (CMT1B)–S63del mice. Accumulation of P0S63del in the ER triggers a persistent unfolded protein response. Protein kinase RNA-like endoplasmic reticulum kinase (PERK) is an ER stress sensor that phosphorylates eukaryotic initiation factor 2 alpha (eIF2alpha) in order to attenuate protein synthesis. We have shown that increasing phosphophorylated-eIF2alpha (P-eIF2alpha) is a potent therapeutic strategy, improving myelination and motor function in S63del mice. Here, we explore the converse experiment: Perk haploinsufficiency reduces P-eIF2alpha in S63del nerves as expected, but surprisingly, ameliorates, rather than worsens S63del neuropathy. Motor performance and myelin abnormalities improved in S63del//Perk+/− compared with S63del mice. These data suggest that mechanisms other than protein translation might be involved in CMT1B/S63del neuropathy. In addition, Perk deficiency in other cells may contribute to demyelination in a non–Schwann-cell autonomous manner. PMID:27095827

Multiplex pyrosequencing of InDel markers for forensic DNA analysis.

PubMed

Bus, Magdalena M; Karas, Ognjen; Allen, Marie

2016-12-01

The capillary electrophoresis (CE) technology is commonly used for fragment length separation of markers in forensic DNA analysis. In this study, pyrosequencing technology was used as an alternative and rapid tool for the analysis of biallelic InDel (insertion/deletion) markers for individual identification. The DNA typing is based on a subset of the InDel markers that are included in the Investigator ® DIPplex Kit, which are sequenced in a multiplex pyrosequencing analysis. To facilitate the analysis of degraded DNA, the polymerase chain reaction (PCR) fragments were kept short in the primer design. Samples from individuals of Swedish origin were genotyped using the pyrosequencing strategy and analysis of the Investigator ® DIPplex markers with CE. A comparison between the pyrosequencing and CE data revealed concordant results demonstrating a robust and correct genotyping by pyrosequencing. Using optimal marker combination and a directed dispensation strategy, five markers could be multiplexed and analyzed simultaneously. In this proof-of-principle study, we demonstrate that multiplex InDel pyrosequencing analysis is possible. However, further studies on degraded samples, lower DNA quantities, and mixtures will be required to fully optimize InDel analysis by pyrosequencing for forensic applications. Overall, although CE analysis is implemented in most forensic laboratories, multiplex InDel pyrosequencing offers a cost-effective alternative for some applications. © 2016 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim.

[Trattamento del disturbo da uso di alcol da un punto di vista psicologico].

PubMed

Coriale, Giovanna; Fiorentino, Daniela; De Rosa, Francesca; Solombrino, Simona; Scalese, Bruna; Ciccarelli, Rosaria; Attilia, Fabio; Vitali, Mario; Musetti, Alessia; Fiore, Marco; Ceccanti, Mauro

2018-01-01

RIASSUNTO. L'elaborazione del piano di trattamento rappresenta un momento molto delicato e complesso del processo terapeutico del disturbo da abuso di alcol (DUA). È la fase in cui le informazioni raccolte da un'équipe di professionisti (medici, psicologi e assistenti sociali) (modello bio-psico-sociale del DUA) vengono messe insieme per decidere il percorso terapeutico più adatto. Per quanto riguarda la parte psicologica, è di notevole importanza scegliere un trattamento clinico in grado di ridurre al minimo la mancata adesione al trattamento e, per i soggetti che rimangono in trattamento, di garantirne l'efficacia. Se da una parte, le tecniche psicoanalitiche e comportamentali hanno fornito le basi della terapia psicologica dell'alcolismo, dall'altra, gli approcci basati sull'evidenza scientifica sono stati elaborati a partire dai principi del colloquio motivazionale e della terapia cognitivo-comportamentale. In questo articolo viene fornita una panoramica dei trattamenti che sono risultati più efficaci nel trattare il DUA e delle modalità temporali più adeguate per monitorare l'efficacia del trattamento.

Life and Utilization Criteria Identification in Design (LUCID). Volume 1

DTIC Science & Technology

1981-10-01

stator, seal /spacer, etc. weights are added to these rotor weights in estimating module weights. Weights of other engine modules (combustor, augmentor...of turbine airfoil/platform cooling air and disk cooling/ seal leakage air), number of vanes and blades for the single stage high-pressure turbine, and...subroutines include hubs, shafts, seals and spacers in estimating rotor weights. Module weight is estimated by adding case and stator weights to the rotor

Direct drive field actuator motors

DOEpatents

Grahn, Allen R.

1998-01-01

A positive-drive field actuator motor including a stator carrying at least one field actuator which changes in dimension responsive to application of an energy field, and at least one drive shoe movable by the dimensional changes of the field actuator to contact and move a rotor element with respect to the stator. Various embodiments of the motor are disclosed, and the rotor element may be moved linearly or arcuately.

Multi-InDel Analysis for Ancestry Inference of Sub-Populations in China

PubMed Central

Sun, Kuan; Ye, Yi; Luo, Tao; Hou, Yiping

2016-01-01

Ancestry inference is of great interest in diverse areas of scientific researches, including the forensic biology, medical genetics and anthropology. Various methods have been published for distinguishing populations. However, few reports refer to sub-populations (like ethnic groups) within Asian populations for the limitation of markers. Several InDel loci located very tightly in physical positions were treated as one marker by us, which is multi-InDel. The multi-InDel shows potential as Ancestry Inference Marker (AIM). In this study, we performed a genome-wide scan for multi-InDels as AIM. After examining the FST distributions in the 1000 Genomes Database, 12 candidates were selected and validated for eastern Asian populations. A multiplexed assay was developed as a panel to genotype 12 multi-InDel markers simultaneously. Ancestry component analysis with STRUCTURE and principal component analysis (PCA) were employed to estimate its capability for ancestry inference. Furthermore, ancestry assignments of trial individuals were conducted. It proved to be very effective when 210 samples from Han and Tibetan individuals in China were tested. The panel consisting of multi-InDel markers exhibited considerable potency in ancestry inference, and was suggested to be applied in forensic practices and genetic population studies. PMID:28004788

Observaciones del CH interestelar y el continuo en 3,3 GHz

NASA Astrophysics Data System (ADS)

Olano, C. A.; Combi, J. A.; Pöppel, W.; Benaglia, P.; Sanz, A. J.; Bava, J. A.

Se informa sobre el proyecto que se lleva a cabo en el IAR con el propósito de observar las líneas hiperfinas del estado fundamental del CH y el continuo en la banda de 3,3 GHz. El nuevo receptor construído en nuestro laboratorio para tal fin se instaló sobre uno de los radiotelescopios, funcionando conjuntamente con los sistemas de procesamiento actuales del IAR. Los resultados de las primeras observaciones, realizadas tanto en las líneas espectrales como en el continuo sobre fuentes conocidas, fueron satisfactorios.

Genetic modifiers of CHEK2*1100delC-associated breast cancer risk.

PubMed

Muranen, Taru A; Greco, Dario; Blomqvist, Carl; Aittomäki, Kristiina; Khan, Sofia; Hogervorst, Frans; Verhoef, Senno; Pharoah, Paul D P; Dunning, Alison M; Shah, Mitul; Luben, Robert; Bojesen, Stig E; Nordestgaard, Børge G; Schoemaker, Minouk; Swerdlow, Anthony; García-Closas, Montserrat; Figueroa, Jonine; Dörk, Thilo; Bogdanova, Natalia V; Hall, Per; Li, Jingmei; Khusnutdinova, Elza; Bermisheva, Marina; Kristensen, Vessela; Borresen-Dale, Anne-Lise; Investigators, Nbcs; Peto, Julian; Dos Santos Silva, Isabel; Couch, Fergus J; Olson, Janet E; Hillemans, Peter; Park-Simon, Tjoung-Won; Brauch, Hiltrud; Hamann, Ute; Burwinkel, Barbara; Marme, Frederik; Meindl, Alfons; Schmutzler, Rita K; Cox, Angela; Cross, Simon S; Sawyer, Elinor J; Tomlinson, Ian; Lambrechts, Diether; Moisse, Matthieu; Lindblom, Annika; Margolin, Sara; Hollestelle, Antoinette; Martens, John W M; Fasching, Peter A; Beckmann, Matthias W; Andrulis, Irene L; Knight, Julia A; Investigators, kConFab/Aocs; Anton-Culver, Hoda; Ziogas, Argyrios; Giles, Graham G; Milne, Roger L; Brenner, Hermann; Arndt, Volker; Mannermaa, Arto; Kosma, Veli-Matti; Chang-Claude, Jenny; Rudolph, Anja; Devilee, Peter; Seynaeve, Caroline; Hopper, John L; Southey, Melissa C; John, Esther M; Whittemore, Alice S; Bolla, Manjeet K; Wang, Qin; Michailidou, Kyriaki; Dennis, Joe; Easton, Douglas F; Schmidt, Marjanka K; Nevanlinna, Heli

2017-05-01

CHEK2*1100delC is a founder variant in European populations that confers a two- to threefold increased risk of breast cancer (BC). Epidemiologic and family studies have suggested that the risk associated with CHEK2*1100delC is modified by other genetic factors in a multiplicative fashion. We have investigated this empirically using data from the Breast Cancer Association Consortium (BCAC). Using genotype data from 39,139 (624 1100delC carriers) BC patients and 40,063 (224) healthy controls from 32 BCAC studies, we analyzed the combined risk effects of CHEK2*1100delC and 77 common variants in terms of a polygenic risk score (PRS) and pairwise interaction. The PRS conferred odds ratios (OR) of 1.59 (95% CI: 1.21-2.09) per standard deviation for BC for CHEK2*1100delC carriers and 1.58 (1.55-1.62) for noncarriers. No evidence of deviation from the multiplicative model was found. The OR for the highest quintile of the PRS was 2.03 (0.86-4.78) for CHEK2*1100delC carriers, placing them in the high risk category according to UK NICE guidelines. The OR for the lowest quintile was 0.52 (0.16-1.74), indicating a lifetime risk close to the population average. Our results confirm the multiplicative nature of risk effects conferred by CHEK2*1100delC and the common susceptibility variants. Furthermore, the PRS could identify carriers at a high lifetime risk for clinical actions.Genet Med advance online publication 06 October 2016.

On a two-dimensional mode-matching technique for sound generation and transmission in axial-flow outlet guide vanes

NASA Astrophysics Data System (ADS)

Bouley, Simon; François, Benjamin; Roger, Michel; Posson, Hélène; Moreau, Stéphane

2017-09-01

The present work deals with the analytical modeling of two aspects of outlet guide vane aeroacoustics in axial-flow fan and compressor rotor-stator stages. The first addressed mechanism is the downstream transmission of rotor noise through the outlet guide vanes, the second one is the sound generation by the impingement of the rotor wakes on the vanes. The elementary prescribed excitation of the stator is an acoustic wave in the first case and a hydrodynamic gust in the second case. The solution for the response of the stator is derived using the same unified approach in both cases, within the scope of a linearized and compressible inviscid theory. It is provided by a mode-matching technique: modal expressions are written in the various sub-domains upstream and downstream of the stator as well as inside the inter-vane channels, and matched according to the conservation laws of fluid dynamics. This quite simple approach is uniformly valid in the whole range of subsonic Mach numbers and frequencies. It is presented for a two-dimensional rectilinear-cascade of zero-staggered flat-plate vanes and completed by the implementation of a Kutta condition. It is then validated in sound generation and transmission test cases by comparing with a previously reported model based on the Wiener-Hopf technique and with reference numerical simulations. Finally it is used to analyze the tonal rotor-stator interaction noise in a typical low-speed fan architecture. The interest of the mode-matching technique is that it could be easily transposed to a three-dimensional annular cascade in cylindrical coordinates in a future work. This makes it an attractive alternative to the classical strip-theory approach.

The Cuernos del Paine mountains in Torres del Paine National Park, Chile, during NASA's AirSAR 2004 campaign

NASA Image and Video Library

2004-03-11

The Cuernos del Paine mountains in Torres del Paine National Park, Chile, during NASA's AirSAR 2004 campaign. AirSAR 2004 is a three-week expedition in Central and South America by an international team of scientists that is using an all-weather imaging tool, called the Airborne Synthetic Aperture Radar (AirSAR), located onboard NASA's DC-8 airborne laboratory. Scientists from many parts of the world are combining ground research with NASA's AirSAR technology to improve and expand on the quality of research they are able to conduct. Founded in 1959, Torres del Paine National Park encompasses 450,000 acres in the Patagonia region of Chile. This region is being studied by NASA using a DC-8 equipped with an Airborne Synthetic Aperture Radar (AirSAR) developed by scientists from NASA’s Jet Propulsion Laboratory. This is a very sensitive region that is important to scientists because the temperature has been consistently rising causing a subsequent melting of the region’s glaciers. AirSAR will provide a baseline model and unprecedented mapping of the region. This data will make it possible to determine whether the warming trend is slowing, continuing or accelerating. AirSAR will also provide reliable information on ice shelf thickness to measure the contribution of the glaciers to sea level.

Development of a 32 Inch Diameter Levitated Ducted Fan Conceptual Design

NASA Technical Reports Server (NTRS)

Eichenberg, Dennis J.; Gallo, Christopher a.; Solano, Paul A.; Thompson, William K.; Vrnak, Daniel R.

2006-01-01

The NASA John H. Glenn Research Center has developed a revolutionary 32 in. diameter Levitated Ducted Fan (LDF) conceptual design. The objective of this work is to develop a viable non-contact propulsion system utilizing Halbach arrays for all-electric flight, and many other applications. This concept will help to reduce harmful emissions, reduce the Nation s dependence on fossil fuels, and mitigate many of the concerns and limitations encountered in conventional aircraft propulsors. The physical layout consists of a ducted fan drum rotor with blades attached at the outer diameter and supported by a stress tuner ring at the inner diameter. The rotor is contained within a stator. This concept exploits the unique physical dimensions and large available surface area to optimize a custom, integrated, electromagnetic system that provides both the levitation and propulsion functions. The rotor is driven by modulated electromagnetic fields between the rotor and the stator. When set in motion, the time varying magnetic fields interact with passive coils in the stator assembly to produce repulsive forces between the stator and the rotor providing magnetic suspension. LDF can provide significant improvements in aviation efficiency, reliability, and safety, and has potential application in ultra-efficient motors, computers, and space power systems.

Impact of fluorescent protein fusions on the bacterial flagellar motor.

PubMed

Heo, M; Nord, A L; Chamousset, D; van Rijn, E; Beaumont, H J E; Pedaci, F

2017-10-03

Fluorescent fusion proteins open a direct and unique window onto protein function. However, they also introduce the risk of perturbation of the function of the native protein. Successful applications of fluorescent fusions therefore rely on a careful assessment and minimization of the side effects, but such insight is still lacking for many applications. This is particularly relevant in the study of the internal dynamics of motor proteins, where both the chemical and mechanical reaction coordinates can be affected. Fluorescent proteins fused to the stator of the Bacterial Flagellar Motor (BFM) have previously been used to unveil the motor subunit dynamics. Here we report the effects on single motors of three fluorescent proteins fused to the stators, all of which altered BFM behavior. The torque generated by individual stators was reduced while their stoichiometry remained unaffected. MotB fusions decreased the switching frequency and induced a novel bias-dependent asymmetry in the speed in the two directions. These effects could be mitigated by inserting a linker at the fusion point. These findings provide a quantitative account of the effects of fluorescent fusions to the stator on BFM dynamics and their alleviation- new insights that advance the use of fluorescent fusions to probe the dynamics of protein complexes.