• Title/Summary/Keyword: tower system

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Eigenvalue Analysis of a Coupled Tower-blade System Considering the Shear Forces of a Nacelle (너셀부 전단력을 고려한 타워-블레이드 연성계의 고유치 해석)

  • Kim, Min-Ju;Kang, Nam-Cheol
    • Transactions of the Korean Society for Noise and Vibration Engineering
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    • v.21 no.6
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    • pp.514-520
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    • 2011
  • Eigenvalue analysis of a wind turbine system was investigated analytically. It is derived that the equations of motion of a tower and a blade are coupled by shear forces inter-connected by boundary conditions. The eigenvalues of the coupled system was calculated using Galerkin method and it is found that the system becomes unstable when the tower and blade modes are coalesced. Further, parameter studies for the eigenvalues were performed with respect to the rotating speed of a blade, nacelle mass, blade and tower densities.

The development of fault monitoring system for lift type parking facility (승강기식 타워주차설비 고장 모니터링 시스템 개발)

  • Lee, W.T.;Cha, J.S.;Jeong, Y.K.;Kim, K.H.;Kim, B.U.
    • Proceedings of the KIEE Conference
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    • 1999.11c
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    • pp.739-741
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    • 1999
  • This paper describes the fault monitoring system for lift type tower parking facilities. This system consists of tower parking facility control panel and monitoring computer, and offers real-time monitoring of parking status and fault detection, and status data acquisition of tower parking system using graphic user interface.

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Nonlinear Dynamic Behaviors of Offshore Guyed Towers (해양구조물 Guyed Tower의 비선형 동적거동)

  • Park, Woo-Sun;Pyen, Chong-Kun;Park, Young-Suk
    • Journal of Korean Society of Coastal and Ocean Engineers
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    • v.3 no.3
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    • pp.126-136
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    • 1991
  • This study is concerned with the nonlinear dynamic behaviors of guyed towers for wave loadings. In order to analyze the nonlinear responses of guyed towers efficiently, the main tower is modeled as an equivalent stick, the guyline system is idealized as a spring with nonlinear stiffness in the horizontal direction. and the pile foundation system is represented as a linear spring in the rotational direction. The wave forces on the main tower are evaluated by using Morison's equation. In order to consider adequately the nonlinearities of the guying system and drag forces due to fluid viscosity. the analyses are performed in the time domain. The mode superposition method is adopted for solving the nonlinear equation of motion efficiently. which is based on the Newmark integration scheme. Numerical analyses are carried out to investigate the sensitivity of two major design parameters for guyed towers. i.e., the clump weight conditions and the base renditions of the tower.

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A study on the analyzing of uncertainty for actual evapotranspiration: flux tower, satellite-based and reanalysis based dataset (실제증발산 자료의 불확실성 파악에 관한 연구: flux tower, 인공위성 및 재분석자료)

  • Baik, Jongjin;Jeong, Jaehwan;Park, Jongmin;Choi, Minha
    • Journal of Korea Water Resources Association
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    • v.52 no.1
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    • pp.11-19
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    • 2019
  • In this study, the actual evapotranspiration products of Global Land Data Assimilation System (GLDAS), Global Land Evaporation Amsterdam Model (GLEAM) and MOD16, which are satellite- and reanalysis-based dataset, were validated at the flux tower sites (i.e., CFK and SMK) managed by Korea Institute of Hydrological Survey, and the uncertainty and correlation analysis were conducted using Triple Collocation (TC) method. The result of validation with the flux tower showed better agreement in the order of GLEAM> GLDAS>MOD16. At the result of three combinations (S1: flux tower vs. GLDAS vs. MOD16, S2: flux tower vs. GLDAS vs. GLEAM, S3: flux tower vs. GLEAM vs. MOD16), the order of best to worst is GLEAM, GLDAS, MOD16, and flux tower for CFK (GLDAS> GLEAM>MOD16>flux tower for SMK). Since the error variance and correlation coefficients of the flux tower show relatively worse performance in TC analysis than the other products, By applying TC method to three products (GLDAS vs. GLEAM vs. MOD16), the uncertainty of each dataset were evaluated at the Korean Peninsula, As a results, the GLDAS and GLEAM performed reasonable performance (low error variance and high correlation coefficient), whereas results of MOD16 showed high error variance and low correlation coefficient at the cropland.

Fatigue Analysis of Welded Toe of Wind Turbine Tower Access Door (Wind Turbine Tower의 Door 용접부에 대한 피로 강도 연구)

  • Han Dong-Young;Koh Jang-Wook;Choi Won-Ho;Lee Seung-Kuh
    • 한국신재생에너지학회:학술대회논문집
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    • 2005.06a
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    • pp.72-75
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    • 2005
  • Recently, as the global warming by fossil fuels become social issues. the interest of renewable energy producing system is increasing rapidly. Among these, wind turbines are most highlighted because of its economic competitiveness. The tower occupying about $20\%$ of overall turbine costs, is one of the main components of wind turbine. Tower access door located to base part of the tower, is used to enter the tower. This is the main structural weak point because of door hole, weldment, etc. In this study, by FEM, we retrieved the maximum van Mises stress at door location and carried out fatigue analysis using stresses at weld toe locations of tower access door part.

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Structural monitoring of a wind turbine steel tower - Part I: system description and calibration

  • Rebelo, C.;Veljkovic, M.;da Silva, L. Simoes;Simoes, R.;Henriques, J.
    • Wind and Structures
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    • v.15 no.4
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    • pp.285-299
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    • 2012
  • This paper describes the development and calibration of a structural monitoring system installed in a 80 meters high steel wind tower supporting a 2.1 MW turbine Wind Class III IEC2a erected in the central part of Portugal. The several signals are measured at four different levels and include accelerations, strains on the tower wall and inside the connection bolts, inclinations and temperature. In order to correlate measurements with the wind velocity and direction and with the turbine operational parameters the corresponding signals are obtained directly from the turbine own monitoring system and are incorporated in the developed system. Results from the system calibration, the structural identification and the initial period of data acquisition are presented in this paper.

Wind-induced responses and equivalent static wind loads of tower-blade coupled large wind turbine system

  • Ke, S.T.;Wang, T.G.;Ge, Y.J.;Tamura, Y.
    • Structural Engineering and Mechanics
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    • v.52 no.3
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    • pp.485-505
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    • 2014
  • This study aimed to develop an approach to accurately predict the wind models and wind effects of large wind turbines. The wind-induced vibration characteristics of a 5 MW tower-blade coupled wind turbine system have been investigated in this paper. First, the blade-tower integration model was established, which included blades, nacelle, tower and the base of the wind turbine system. The harmonic superposition method and modified blade element momentum theory were then applied to simulate the fluctuating wind field for the rotor blades and tower. Finally, wind-induced responses and equivalent static wind loads (ESWL) of the system were studied based on the modified consistent coupling method, which took into account coupling effects of resonant modes, cross terms of resonant and background responses. Furthermore, useful suggestions were proposed to instruct the wind resistance design of large wind turbines. Based on obtained results, it is shown from the obtained results that wind-induced responses and ESWL were characterized with complicated modal responses, multi-mode coupling effects, and multiple equivalent objectives. Compared with the background component, the resonant component made more contribution to wind-induced responses and equivalent static wind loads at the middle-upper part of the tower and blades, and cross terms between background and resonant components affected the total fluctuation responses, while the background responses were similar with the resonant responses at the bottom of tower.

Soil-structure interaction effects on seismic behavior of a hyperbolic cooling tower using three-parameter Vlasov foundation model

  • Karakas, Ali I.;Ozgan, Korhan;Daloglu, Ayse T.
    • Earthquakes and Structures
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    • v.14 no.1
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    • pp.85-94
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    • 2018
  • The paper focuses on the seismic responses of a hyperbolic cooling tower resting on soil foundation represented by the three-parameter Vlasov elastic soil model. The three-parameter soil model eliminates the necessity of field testing to determine soil parameters such as reaction modulus and shear parameter. These parameters are calculated using an iterative procedure depending on the soil surface vertical deformation profile in the model. The soil and tower system are modeled in SAP2000 structural analysis program using a computing tool coded in MATLAB. The tool provides a two-way data transfer between SAP2000 and MATLAB with the help of Open Application Programming Interface (OAPI) feature of SAP2000. The response spectrum analyses of the tower system with circular V-shaped supporting columns and annular raft foundation on elastic soil are conducted thanks to the coded tool. The shell and column forces and displacements are presented for different soil conditions and fixed raft base condition to investigate the effects of soil-structure interaction. Numerical results indicate that the flexibility of soil foundation leads to an increase in displacements but a decrease in shell membrane and column forces. Therefore, it can be stated that the consideration of soil-structure interaction in the seismic response analysis of the cooling tower system provides an economical design process.

Dynamic analysis of wind-vehicle-bridge system considering additional moments of non-uniform winds by wind shielding effect of multi-limb tower

  • Xu Han;Huoyue Xiang;Xuli Chen;Yongle Li
    • Wind and Structures
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    • v.36 no.1
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    • pp.1-14
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    • 2023
  • To evaluate the wind shielding effect of bridge towers with multiple limbs on high-speed trains, a wind tunnel test was conducted to investigate the aerodynamic characteristics of vehicles traversing multi-limb towers, which represented a combination of the steady aerodynamic coefficient of the vehicle-bridge system and wind environment around the tower. Subsequently, the analysis model of wind-vehicle-bridge (WVB) system considering the additional moments caused by lift and drag forces under nonuniform wind was proposed, and the reliability and accuracy of the proposed model of WVB system were verified using another model. Finally, the factors influencing the wind shielding effect of multi-limb towers were analyzed. The results indicate that the wind speed distributions along the span exhibit two sudden changes, and the wind speed generally decreases with increasing wind direction angle. The pitching and yawing accelerations of vehicles under nonuniform wind loads significantly increase due to the additional pitching and yawing moments. The sudden change values of the lateral and yawing accelerations caused by the wind shielding effect of multi-limb tower are 0.43 m/s2 and 0.11 rad/s2 within 0.4 s, respectively. The results indicate that the wind shielding effect of a multi-limb tower is the controlling factor in WVB systems.

Thermal Performance Characteristics of Closed-Wet Cooling Tower (밀폐형 냉각탑의 열성능 특성에 관한 실험적 연구)

  • Sarker, M.M.A.;Kim, E.P.;Moon, C.G.;Yoon, J.I.
    • Journal of Power System Engineering
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    • v.9 no.2
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    • pp.88-92
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    • 2005
  • The experiment of thermal performance about closed-wet cooling tower was conducted in this study. A closed cooling tower is a device similar to a general cooling tower, but with cooling tower replaced by a heat exchanger. The test section for this experiment has the process that the cooling water flows from the top of the heat exchanger to the bottom side in the inner part of the tube, and spray water flows in the gravitational direction in the outer side. Air comes in direct contact with the spray water at the outer side of the tube while passing from the lower the upper part having a counterflow to the spray water. The heat transfer pipe used in this experiment is a bare-type tube having an outer diameter of 15.88mm. The heat exchanger is consisted of seven rows and fifteen columns. In this experiment, thermal performance of the cooling tower is derived from overall heat transfer coefficients between the process fluid and sprayed water and volumetric overall mass transfer coefficient between sprayed water and air.

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