• 제목/요약/키워드: Vortex turbine

검색결과 200건 처리시간 0.029초

후류와 타워의 영향을 고려한 수평축 풍력발전기 블레이드의 비정상 하중 예측을 위한 새로운 자유후류기법의 연구 (Development of a new free wake model considering a waketower interaction for a horizontal axis wind turbine)

  • 신형기;박지웅;이수갑;김주언
    • 신재생에너지
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    • 제1권1호
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    • pp.54-63
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    • 2005
  • A critical issue in the field of the rotor aerodynamics is the treatment of the wake. The wake is of primary importance in determining overall aerodynamic behavior, especially, a wind turbine blade includes the unsteady airloads problem. In this study, the wake generated by blades are depicted by a free wake model to analyse unsteady loading on blade and a new free wake model named Finite Vortex Element(FVE hereafter) is devised in order to include a wake-tower interaction. In this new free wake model, blade-wake-tower interaction is described by cutting a vortex filament when the filament collides with a tower. This FVE model is compared with a conventional free wake model and verified by a comparison with NRELand SNU wind tunnel model. A comparison with NREL and SNU data shows validity and effectiveness of devised FVE free wake model and an efficient.

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가스 터빈 축 내부의 비정상 유동의 불안정성 (Transient Flow Instability inside a Gas Turbine Shaft)

  • 허남건;원찬식
    • 한국유체기계학회 논문집
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    • 제2권1호
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    • pp.103-107
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    • 1999
  • Transient flow inside a hollow shaft of a Gas Turbine engine during sudden engine stop may result in non uniform heat transfer coefficients in the shaft due to flow instability similar to steady Taylor vortex, which may decrease the lifetime of the shaft. In the present study, transient Taylor vortex phenomena inside a suddenly stopped hollow shaft are studied analytically. Flow visualization is also performed to study the shape and onset time of Taylor Vortices for various initial rotational speed.

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블레이드 앞전 3차원 형상 변형에 의한 터빈 캐스케이드 내의 이차유동 제어 (Secondary flow Control in the Turbine Cascade with the Three-Dimensional Modification of Blade Leading Edge)

  • 김정래;문영준;정진택
    • 대한기계학회논문집B
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    • 제26권11호
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    • pp.1552-1558
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    • 2002
  • The blade leading edge is modified to control the secondary flow generated in the turbine cascade with fence by intensifying the suction side branch of the horseshoe vortex. The incompressible Navier-Stokes equations are numerically solved with a high Reynolds number k-$\varepsilon$ turbulence closure model for investigating the vortical flows in the turbine cascade. The computational results of total pressure loss coefficients in the wake region are first compared with experiments for validation. The structure and strength of the passage vortex near the suction surface are examined by testing various geometrical parameters of the turbine blade leading edge.

축류터빈 동익 내부의 누설유동에 관한 수치해석 (Numerical Analysis of Tip Leakage Flows in Axial Flow Turbine Rotors)

  • 정희택
    • 동력기계공학회지
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    • 제9권1호
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    • pp.23-29
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    • 2005
  • Numerical analysis of three-dimensional viscous flow-fields in the turbine rotor passages was carried out to investigate flow physics including the interaction between secondary vortices, tip leakage vortex, and the rotor wake. The blade tip geometry was accurately modeled adopting the embedded H grid system. An explicit four-stage Runge-Kutta scheme was used for the time integration of both the mean flow and turbulence equations. The computational results for the entire turbine rotor flows, particularly the tip clearance flow and the secondary flows, were interpreted and compared with the experimental data from the Penn State turbine stage. The predictions for major features of the flow field have been found to be in good agreement with the experimental data.

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축류터빈 동익 내부의 누설유동에 관한 수치해석 (Numerical Analysis of Tip Leakage Flows in Axial Flow Turbine Rotors)

  • 정희택
    • 한국전산유체공학회:학술대회논문집
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    • 한국전산유체공학회 2003년도 추계 학술대회논문집
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    • pp.171-175
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    • 2003
  • Numerical analysis of three-dimensional viscous flow-fields in the turbine rotor passages is carried out to investigate flow physics including the interaction between secondary vortices, tip leakage vortex, and the rotor wake. The blade tip geometry is accurately modeled adopting the embedded H grid topology. An explicit four-stage Runge-Kutta scheme is used for the time integration of both the mean flow and turbulence equations. The computational results for the entire turbine rotor flows, particularly the tip clearance flow and the secondary flows, are interpreted and compared with the experimental data from the Penn State turbine stage. Good agreement between the experimental data and the numerical prediction was achieved in the sense of the major features of the flow fields.

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Effects of Squealer Rim Height on Aerodynamic Losses Downstream of a High-Turning Turbine Rotor Blade

  • Lee, Sang-Woo;Chae, Byoung-Joo
    • 한국추진공학회:학술대회논문집
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    • 한국추진공학회 2008년 영문 학술대회
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    • pp.160-167
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    • 2008
  • The effects of squealer rim height on three-dimensional flows and aerodynamic losses downstream of a high-turning turbine rotor blade have been investigated for a typical tip gap-to-chord ratio of h/c=2.0%. The squealer rim height-to-chord ratio is changed to be $h_{st}/c$=0.00(plane tip), 1.37, 2.75, 5.51, and 8.26%. Results show that as $h_{st}/c$ increases, the tip leakage vortex tends to be weakened and the interaction between the tip leakage vortex and the passage vortex becomes less severe. The squealer rim height plays an important role in the reduction of aerodynamic loss when $h_{st}/c{\leq}2.75%$. In the case of $h_{st}/c{\geq}5.51%$, higher squealer rim cannot provide an effective reduction in aerodynamic loss. The aerodynamic loss reduction by increasing $h_{st}/c$ is limited only to the near-tip region within a quarter of the span from the casing wall.

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Ristorcelli의 압축성 난류 모형을 이용한 초음속 유동의 계산 (Computations of Supersonic Flow with Ristorcelli′s Compressible Turbulence Model)

  • 박창환;박승오
    • 한국전산유체공학회지
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    • 제8권3호
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    • pp.1-6
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    • 2003
  • Three-dimensional endwall flow within a linear cascade passage of high performance turbine blade is simulated with a 3-D Wavier-Stokes CFD code (MOSA3D), which is based on body-fitted coordinate system, pressure-correction and finite volume method. the endwall flow characteristics, including the development and generation of horseshoe vortex, passage vortex, etc. are clearly simulated, consistent with the generally known tendency The effects of both turbulence model and convective differencing scheme on the Prediction performance of endwall flow are systematically analyzed in the present paper. The convective scheme is found to have stronger effect than the turbulence modei on the prediction performance of endwall flow. The present simulation result also indicates that the suction leg of the horseshoe vortex continues on the suction side until it reaches the trailing edge.

역설계 기법을 이용한 풍력터빈 에어포일 형상 설계 (Inverse Airfoil Design for Wind Turbine)

  • 유기완;박명호
    • 풍력에너지저널
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    • 제4권2호
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    • pp.55-60
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    • 2013
  • The mathematical implementation for inverse airfoil design of wind turbines is presented using vortex panel method based on assumptions of the two-dimensional incompressible potential flow. The vortex panel method employs linear distribution of the vortex strength to obtain the well converged solution. Stream function is adopted to get the basic formula for the inverse airfoil design, and a symmetric seed airfoil is given for initial data of the iteration approach. The final airfoil shape has been compared with the original airfoil shape for validation of the mathematical procedure.

Overload Surge Investigation Using CFD Data

  • Flemming, Felix;Foust, Jason;Koutnik, Jiri;Fisher, Richard K.
    • International Journal of Fluid Machinery and Systems
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    • 제2권4호
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    • pp.315-323
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    • 2009
  • Pressure oscillations triggered by the unstable interaction of dynamic flow features of the hydraulic turbine with the hydraulic plant system - including the electrical design - can at times reach significant levels and could lead to damage of plant components or could reduce component lifetime significantly. Such a problem can arise for overload as well as for part load operation of the turbine. This paper discusses an approach to analyze the overload high pressure oscillation problem using computational fluid dynamic (CFD) modeling of the hydraulic machine combined with a network modeling technique of the hydraulic system. The key factor in this analysis is the determination of the overload vortex rope volume occurring within the turbine under the runner which is acting as an active element in the system. Two different modeling techniques to compute the flow field downstream of the runner will be presented in this paper. As a first approach, single phase flow simulations are used to evaluate the vortex rope volume before moving to more sophisticated modeling which incorporates two phase flow calculations employing cavitation modeling. The influence of these different modeling strategies on the simulated plant behavior will be discussed.

An enhanced analytical calculation model based on sectional calculation using a 3D contour map of aerodynamic damping for vortex induced vibrations of wind turbine towers

  • Dimitrios Livanos;Ika Kurniawati;Marc Seidel;Joris Daamen;Frits Wenneker;Francesca Lupi;Rudiger Hoffer
    • Wind and Structures
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    • 제38권6호
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    • pp.445-459
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    • 2024
  • To model the aeroelasticity in vortex-induced vibrations (VIV) of slender tubular towers, this paper presents an approach where the aerodynamic damping distribution along the height of the structure is calculated not only as a function of the normalized lateral oscillation but also considering the local incoming wind velocity ratio to the critical velocity (velocity ratio). The three-dimensionality of aerodynamic damping depending on the tower's displacement and the velocity ratio has been observed in recent studies. A contour map model of aerodynamic damping is generated based on the forced vibration tests. A sectional calculation procedure based on the spectral method is developed by defining the aerodynamic damping locally at each increment of height. The proposed contour map model of aerodynamic damping and the sectional calculation procedure are validated with full-scale measurement data sets of a rotorless wind turbine tower, where good agreement between the prediction and measured values is obtained. The prediction of cross-wind response of the wind turbine tower is performed over a range of wind speeds which allows the estimation of resulting fatigue damage. The proposed model gives more realistic prediction in comparison to the approach included in current standards.