• Title, Summary, Keyword: double-rotor

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A Study on Double Flan of Wells Turbine for Wave Power Conversion (파력발전용 웰즈터빈의 더블플랩에 관한 연구)

  • Kim, J.H.;Kim, B.S.;Yoon, S.H.;Lee, Y.W.;Lee, Y.H.
    • Proceedings of the KSME Conference
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    • pp.616-621
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    • 2001
  • A numerical investigation was performed to determine the effect of airfoil on the optimum flap height using NACA 0021 Wells turbine. The five double flaps which have 0.5% chord height difference were selected. A Navier-Stokes code, FLUENT, was used to calculate the flow field of the Wells turbine. The basic feature of the Wells turbine is that even though the cyclic airflow produces oscillating axial forces on the airfoil blades, the tangential force on the rotor is always in the same direction. Geometry used to define the 3-D numerical grid is based upon that of an experimental test rig. This paper tries to analyze the optimum double flap of Wells turbine with the numerical analysis.

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Air-gap Control According to Y and Delta Connections of Double-sided Air-gap Permanent Magnet Synchronous Motor with Independent Three-phase Structure (독립 3상 구조를 갖는 이중공극형 영구자석 동기전동기의 Y 및 Delta 결선에 따른 공극제어)

  • Heo, Chan-Nyeong;Hwang, Seon-Hwan
    • The Transactions of the Korean Institute of Power Electronics
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    • v.22 no.3
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    • pp.249-255
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    • 2017
  • This paper presents air-gap control according to Y and Delta connections of a double-sided air-gap permanent magnet synchronous motor (DA-PMSM) with independent three-phase structure. In particular, the DA-PMSM used in this study can be applied to low-speed and high-torque applications, such as wind turbines, tidal power generations, and electric propulsion ships, because of its modular stators and a rotor with numerous permanent magnets. Unlike conventional three-phase machines, the DA-PMSM has a symmetrical configuration with double-sided air-gap. Therefore, Y/Delta winding connections and serial/parallel configurations between stator modules are possible. To identify the DA-PMSM operating characteristics, mathematical modeling is analyzed according to the Y/Delta connections. Moreover, air-gap control performances by applying the winding connection methods are verified through experimental results.

Stability analysis of pump using finite element method (유한요소법에 의한 펌프축계의 안정성해석)

  • 양보석
    • Journal of the Korean Society of Marine Engineering
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    • v.10 no.4
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    • pp.31-40
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    • 1986
  • With the tendency toward high speed and high pressure in centrifugal pumps, the problem of sub-synchronous vibration has arisen, caused by the hydraulic forces of the working fluid, such as wearring, balance piston, impeller, etc.. These forces can drastically alter the rotor critical speeds and stability characteristics, and can be acted significant destabilizing forces. For preventing such self-excited vibration, the desing of the rotor system needs, which would secure the stability of the machine. In this paper, a procedure is presented for dynamic modeling of rotor-bearing-seal-impeller systems which consist of rigid disks, distributed parameter finite rotor elements and discrete bearings, seals and impellers. A finite element model including the effects of rotatory inertia and gyroscopic moments is developed using the consistent matrix approach. The technique of dynamic matrix reduction is applied to the shaft matrices to reduce them to a set of matrices of dynamic of significantly fewer degrees of freedom. The representation of bearing, seal and impeller elements is in term of linearized stiffness and damping matrices by reasonably small perturbations from equilibrium. The stability behavior of a typical double suction centrifugal pump is presented. Results show the influence of clearance and flow conditions on running speeds and stability characteristics.

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Comparison and Analysis on magnetic structures of Switched Reluctance Motors (Switched Reluctance Motor의 자기적 구조에 대한 비교 해석)

  • Oh, Seok-Gyu
    • Journal of the Korea Institute of Information and Communication Engineering
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    • v.20 no.1
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    • pp.131-141
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    • 2016
  • SRM is designed to meet operating standards such as low cost, simple magnetic structure, a desired operating speed range, high efficiency, high performance, and good matching for DC power. The magnetic flux of SRM is independent of its direction to develop a torque and it allows the flexible characteristics of the magnetic structure for SRM. In this paper, SRM can widely classify two types, Radial-Flux SRM and Axial-Flux SRM, according to the flux direction. Radial-Flux SRM includes Conventional, Segmented stator and rotor, and Double stator SRM, etc. and Axial-Flux SRM includes C-core stator and the Axial-airgap SRM. This paper is subjected the basic characteristics to select the best of the magnetic structure of SRM in the appropriate application by the classification of SRM.

A CFD Study on Wells Turbine Flap for Wave Power Generation (CFD에 의한 파력발전용 웰즈터빈의 플랩에 관한 연구)

  • Kim, J.H.;Kim, B.S.;Choi, M.S.;Lee, Y.W.;Lee, Y.H.
    • 유체기계공업학회:학술대회논문집
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    • pp.520-525
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    • 2003
  • A numerical investigation was performed to determine the effect of airfoil on the optimum flap height using NACA0015 Wells turbine. The five double flaps which have 0.5% chord height difference were selected. A Wavier-Stokes code, CFX-TASCflow, was used to calculate the flow field of the Wells turbine. The basic feature of the Wells turbine is that even though the cyclic airflow produces oscillating axial forces on the airfoil blades, the tangential force on the rotor is always in the same direction. Geometry used to define the 3-D numerical grid is based upon that of an experimental test rig. This paper tries to analyze the optimum double flap of Wells turbine with the numerical analysis.

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A Study on the Flow characteristics of Wells Turbine for Wave Power Conversion by Various Flap Shape (파력발전용 웰즈터빈의 Flap형상변화에 따른 유동 특성에 관한 연구)

  • Kim, Dong-Kyun;Choi, Gab-Song;Kim, Jeong-Hwan
    • Journal of the Korean Solar Energy Society
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    • v.26 no.2
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    • pp.1-7
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    • 2006
  • A numerical investigation was performed to determine the effect of airfoil on the optimum flap height using NACA0015 Wells turbine. The five double flaps which have 0.5% difference were selected. A Navier-Stokes code, CFX-TASCflow, was used to calculate the flow field of the Wells turbine. The basic feature of the Wells turbine is that even though the cyclic airflow produces oscillating axial forces on the airfoil blades, the tangential force on the rotor is always in the same direction. Geometry used to define the three dimension numerical grid is based upon that of an experimental test rig. This paper tries to disign the double flap of Wells turbine with the numerical analysis.

Design and Analysis of Double Excited 3-Degree-of-Freedom Motor for Robots

  • Kwon, Byung-Il;Kim, Young-Boong
    • Journal of Electrical Engineering and Technology
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    • v.6 no.5
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    • pp.618-625
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    • 2011
  • This paper presents a double excited three degree-of-freedom (3DOF) motor. The proposed 3DOF motor is designed with a laminated structure, making it easy to manufacture. In addition, it has windings on the stator and rotor, and does not require an expensive permanent magnet. We explain the structure, principle of motion, and design of the proposed motor, and perform an analysis of the static characteristics using the two- and three-dimensional finite element methods (3D FEM). The feasibility of 3D FEM analysis is confirmed by comparing the 3D FEM analysis and experimental results for the rolling and pitching motion. We also confirm the occurrence of holding torque in every motion.

Design and Analysis of Double Stator Type Bearingless Switched Reluctance Motor (이중고정자구조를 가지는 베어링리스 스위치드 릴럭턴스 전동기의 설계와 해석)

  • Peng, Wei;Lee, Dong-Hee;Ahn, Jin-Woo
    • The Transactions of The Korean Institute of Electrical Engineers
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    • v.60 no.4
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    • pp.746-752
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    • 2011
  • In this paper, a novel bearingless switched reluctance motor (BLSRM) with double stator is proposed. This motor has two stators. Torque stator is outside, which mainly produces rotational torque. Radial force stator is inside, which mainly generates radial force to suspend the rotor. A novel structure and operating principle are presented. And characteristics of the proposed structure such as magnetic flux distribution, inductance, torque and radial force are analyzed through finite element method. From the analysis, the proposed BLSRM has linear characteristic of radial force and independence from torque current.

A Study on the Design of Wells Turbine for Wave Power Conversion by Various Flap Shape (1) (플랩현상 변화에 따른 파력발전용 웰즈터빈의 형상설계에 관한 연구(1))

  • Kim D.K.;Kim J.H.;Choi Y,H.;Bae S.T.;Lee Y.W.;Lee Y.H.
    • Korean Journal of Computational Design and Engineering
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    • v.9 no.3
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    • pp.253-259
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    • 2004
  • A numerical investigation was performed to determine the effect of airfoil on the optimum flap height using NACA0015 Wells turbine. The five double flaps which have 0.5% difference were selected. A Navier-Stokes code, CFX-TASCflow, was used to calculate the flow field of the Wells turbine. The basic feature of the Wells turbine is that even though the cyclic airflow produces oscillating axial forces on the airfoil blades, the tangential force on the rotor is always in the same direction. Geometry used to define the three dimension numerical grid is based upon that of an experimental test rig. This paper tries In optimized disign the double flap of Wells turbine with the numerical analysis.