• Title/Summary/Keyword: Pitch curve

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A study of Power Performance for 50kW Wind Turbine (50kW 풍력발전기의 출력 성능에 관한 연구)

  • Kim, Hyoung-Gil;Kong, Jeong-Sik;Kwon, Ki-Jin;Oh, Jin-Hun;Moon, Chae-Joo
    • Proceedings of the KIEE Conference
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    • 2015.07a
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    • pp.1068-1069
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    • 2015
  • Wind turbines have an enormous potential for decentralized electricity generation. In recent years, there has been an increasing worldwide interest in small/medium wind systems. This paper presents the results of power performance testing conducted on a 50 kW turbine located in Yeonggwang test-bed. The turbine system is a pitch, active yaw, variable speed, upwind, three blade with a direct drive PMSG. This thesis covers the operation of variable speed wind turbines with pitch-yaw control. The system considered is controlled to generate maximum energy while minimizing loads. The data include power, wind speed, and direction from meteorological towers, and nacelle anemometer readings and output from turbine. The analysis concentrates on the effect of the load on the power-wind speed curve of the turbine.

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Mechanical Loads Analysis and Control of a MW Wind Turbine (MW 규모 풍력 터빈의 기계적 하중 특성 해석 및 제어)

  • Nam, Yoon-Su;Choi, Han-Soon
    • Journal of the Korean Society for Precision Engineering
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    • v.27 no.9
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    • pp.26-33
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    • 2010
  • A multi-MW wind turbine is a huge mechanical structure, of which the rotor diameter is more or less than 100 m. Rotor blades experience unsymmetric mechanical loads caused by the interaction of incoming wind with the tower and wind shear effect. These mechanical loads are transferred to the entire structure of the wind turbine and are known as the major reasons for shortening the life span of the wind turbine. Therefore, as the size of wind turbine gets bigger, the mitigation of mechanical loads becomes more important issue in wind turbine control system design. In this paper, a concept of an individual pitch control(IPC), which minimizes the mechanical loads of rotor blades, is introduced, and simulation results using IPC are discussed.

Bearingless Rotor Hub Composite Component Fatigue Analysis of Utility Helicopter to perform the Basic Mission (기본임무를 수행하는 기동헬기에 적용될 무베어링 허브 복합재 구성품 피로수명 해석)

  • Kim, Taejoo;Kee, Youngjoong;Kim, Deog-kwan;Kim, Seung-ho
    • Proceedings of the Korean Society for Noise and Vibration Engineering Conference
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    • 2013.04a
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    • pp.383-389
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    • 2013
  • Rotor system is a very important part which produces lift, thrust and control force in helicopter. Component of rotor system must endure various flight load for the required life. In helicopter rotor system, bearingless rotor system is the highest technology rotor system compare with articulated and hingeless rotor system. Baaringless rotor system is not include mechanical flap hinge, lag hinge and pitch bearing. Bearingless rotor component flexbeam which made by composite material has conduct hinge and bearing role instead of mechanical flap hinge, lag hinge and pitch bearing. These characteristics has less part number and lass weight than others. In this paper, conduct safe life analysis of bearingless composite component flexbeam and torque tube applying to utility helicopter load condition.

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Study of Boundary Tone in Mandarin Chinese (표준 중국어의 경계억양에 관한 연구)

  • Sohn Nam-Ho
    • Proceedings of the KSPS conference
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    • 2003.05a
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    • pp.43-47
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    • 2003
  • This paper is phonetic study of $F_{0}$ range and boundary tone in Mandarin Chinese. The production data from 6 Chinese speakers show that there are declination, pitch resetting and tonal variation of boundary tone. In declarative sentence, $F_{0}$ declines gradually over the utterance but mid-sentence boundary prevents $F_{0}$ of following syllable from declining because of pitch resetting. $F_{0}$ range of syllable is expanded before the mid- and final sentence boundaries. In interrogative one, $F_{0}$ ascends gradually over the utterance and mid-sentence boundary makes $F_{0}$ of following syllable rise more. $F_{0}$ range of sentence final syllable is expanded and $F_{0}$ contour shows rising curve.

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LQR control of Wind Turbine (풍력터빈의 LQR 제어)

  • Nam, Yoon-su;Jo, Jang-whan;Lim, Chang-Hee;Park, Sung-su;Bottasso, Carlo L.
    • Journal of Wind Energy
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    • v.2 no.1
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    • pp.74-81
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    • 2011
  • This paper deals with the application of LQ control to the power curve tracking control of wind turbine. However, two more additional tasks are required to apply the LQR theory to wind turbine control. One is the tracking problem instead of regulation, because the wind turbine is controlled as variable speed and variable pitch. The other is LQ integral control., because the rotor speed should be tightly controlled without any steady state error. Starting from the analysis of wind characteristics, design requirement of a wind turbine control system is defined. A design procedure of LQ tracking with integral control is introduced. The performance of LQ tracking system is analyzed and evaluated by numeric simulation.

Inverse Kinematic Analysis of a Three Dimensional Binary Robot Manipulator (3차원 2진 로봇 머니퓰레이터의 역기구학적 해석)

  • Ryu, Gil-Ha;Rhee, Ihn-Seok
    • Journal of the Korean Society for Precision Engineering
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    • v.16 no.4 s.97
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    • pp.205-212
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    • 1999
  • A three dimensional binary parallel robot manipulator uses actuators which have only two stable states and its structure is variable geometry truss. As a result, it has a finite number of states and fault tolerant mechanism because of kinematic redundancy. This kind of robot manipulator has some advantages compared to a traditional one. Feedback control is not required, task repeatability can be very high, and finite state actuators are generally inexpensive. Because the number of states of a binary robot manipulator grows exponentially with the number of actuators it is very difficult to solve and inverse kinematic problem. The goal of this paper is to develop an efficient algorithm to solve an inverse kinematic problem of three dimensional binary parallel robot manipulator using a backbone curve when the number of actuators are too much. We first derive the coordinate transformations associated with a three degree of freedom in-parallel actuated robot manipulator. The backbone curve is generated optimally by considering the maximum roll and pitch angles of the robot manipulator configuration and length of link. Then, the robot manipulator is fitted along the backbone curve with some criterion.

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A Study on the Adequate Radius of Circular Arc in the Involute-Circular Arc Composite Tooth Profile (인벌류우트-원호 합성치형의 적정 원호반경에 대한 연구)

  • 정인승;손지원;윤갑영
    • Transactions of the Korean Society of Mechanical Engineers
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    • v.11 no.2
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    • pp.296-303
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    • 1987
  • The composite gear which is composed of involute curve and circular arc has been studied. In the vicinity of pitch point, its profile is an involute curve, and in the dedenum, a circular arc. The curve in the dedendum is generated by the circular arc of the mating gear. Though the available range between minimum and maximum radius of circular arc can be given by existing tooth profile equation, there was no formulation which relates design parameters to the desired radius. It is attempted to get the formula for the radius of circular arc as a function of design parameters, such as unwounded angle, number of teeth, module, and pressure angle. The radius of circular arc, the chordal tooth thickness at working root circle, nominal bending stress, Hertz stress and contact ratio obtained from derived formula are compared with those of the existing design criteria. And these are compared with those of involute gear.

Air-side Performance of Louver-Finned Flat Aluminum Heat Exchangers at a Low Velocity Region (저속 영역에서 루버휜이 장착된 평판관형 알루미늄 열교환기의 공기측 전열 성능에 대한 실험적 연구)

  • Cho, Jin-Pyo;Oh, Wang-Kyu;Kim, Nae-Hyun;Youn, Baek
    • Transactions of the Korean Society of Mechanical Engineers B
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    • v.26 no.12
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    • pp.1681-1691
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    • 2002
  • The heat transfer and pressure drop characteristics of heat exchangers with louver fins were experimentally investigated. The samples had small fin pitches (1.0 mm to 1.4 mm), and experiments were conducted up to a very low frontal air velocity (as low as 0.3 m/s). At a certain Reynolds number (critical Reynolds number), the flattening of the heat transfer coefficient curve was observed. The critical Reynolds number was insensitive to the louver angle, and decreased as the louver pitch to fin pitch ratio (L$_{p}$F$_{p}$) decreased. Existing correlations on the critical Reynolds number did not adequately predict the data. It is suggested that, for proper assessment of the heat transfer behavior, the louver pattern in addition to the flow characterization need to be considered. The heat transfer coefficient increased as the fin pitch decreased. At low Reynolds numbers, however, the trend was reversed. Possible explanation is provided considering the louver pattern between neighboring fins. Different from the heat transfer coefficient, the friction factor did not show the flattening characteristic. The reason may be attributed to the form drag by louvers, which offsets the decreased skin friction at a low Reynolds number. The friction factor increased as the fin pitch decreased and the louver angle increased. A new correlation predicted 92% of the heat transfer coefficient and 90% of the friction factor within $\pm$10%.10%.

NON-DEVELOPABLE RULED SURFACES WITH TIMELIKE RULING IN MINKOWSKI 3-SPACE

  • YANG, YUN;YU, YANHUA
    • Bulletin of the Korean Mathematical Society
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    • v.52 no.4
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    • pp.1339-1351
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    • 2015
  • In this paper, using pseudo-spherical Frenet frame of pseudo-spherical curves in hyperbolic space, we define the notion of the structure functions on the non-developable ruled surfaces with timelike ruling. Then we obtain the properties of the structure functions and a complete classification of the non-developable ruled surfaces with timelike ruling in Minkowski 3-space by the theories of the structure functions.

Upper Bound Analysis for Forging of Spur Gears (스퍼어기어의 단조에 관한 상계해석)

  • 조해용;최재찬;최종웅
    • Proceedings of the Korean Society for Technology of Plasticity Conference
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    • 1995.03a
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    • pp.41-53
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    • 1995
  • Forging of spur gears has been investigated by means of upper-bound method. The term forging means forging of spur gears with solid cylindrical billets, hollow billets with flat punch. Kinematically admissbile velocity field for forging of spur gears has been proposed in this study. The 1/2 pitch of spur gear has been divided into seven dieformation regions, wherein, an involute curve has been introduced to represent the shape of die profile. Especially neutral surface has been introduced intor forging of hollow gears from hollow billets. By using the kinematically admissible velocity field, the powder requirements and suitable conditions for forging fo spur gears were successfully calculated with numerical method. According to the analysis , the acceptable number of teeth for forging of spur gears is from 15 to 20.

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