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中國造船暨輪機工程學刊 EIScopus

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篇名 非線性波作用下離岸風機基樁之溯升高度和波浪荷載模擬
卷期 34:4
並列篇名 THE SIMULATION OF RUN-UP HEIGHTS AND WAVE LOADS OF OFFSHORE WIND TURBINES INDUCED BY NONLINEAR WAVES
作者 陳靖夫林宇銜
頁次 197-206
關鍵字 計算流體力學離岸風力發電機基樁溯升波浪荷載體積分率法CFDOffshore Wind TurbinesRun-UpVolume of FractionEIScopus
出刊日期 201511

中文摘要

本研究主要以計算流體力學(computational fluid dynamics, CFD)軟體,並以RANS方程式搭配k-s紊流 模式作為求解器,模擬風機基椿在不同波浪條件下之溯升與波浪荷載情形。在自由液面的設定上,則是使 用體積分率(volume of fraction, VOF)方法處理自由液面問題。爾後,再以此方法模擬單椿式、三腳管式以 及重力式三種不同單一風機基椿型式,在不同波浪條件影響下的波浪荷載情形與溯升高度變化。經模擬分 析後發現,在波浪尖銳度較高、週期較短的波浪環境下,三種不同種類的基椿皆有較高的溯升高度,但基 椿所受到的波力卻較小;反之,波浪尖銳度較小、週期較長的波浪條件下,雖然溯升高度較小,但波力 卻會對基椿造成較大的波浪荷載。最後,本文以史托克斯二階理論為基礎,並以速度停滯頭理論作為波浪 溯升半經驗公式之參考依據,探討溯升校正因子在不同基椿形式及波浪條件下之變化;情形。結果指出,溯 升校正因子會隨著波浪尖銳度及最大溯升高度的増加而有減少的趨勢。

英文摘要

A hydrodynamic simulation of wave run-up heights and wave loads on three types of wind turbine foundations, i.e. monopile, gravity-based and tripod support structures, was conducted using a RANS solver for incompressible fluid flows, employing k-ε turbulent closure. The present CFD model based on the commercial software, FLUENT, is provided to calculate the maximum wave heights and wave loads that the foundations may experience during the wave propagation in Stokes second order wave theory. The wave run-up on different designs of wind turbine foundations is discussed by the breakwater effect, which would be the dominant factor deciding the minimum air-gap requirement of working platform. Thus, a series of numerical experiments with different cases of wave steepness ka as well as scattering parameter kA were conducted by comparing the effects of wave characteristics on these support structures. Due to the contribution of the present CFD model, a semi-empirical formula is calibrated based on velocity stagnation head theory for crest kinematics. It is obvious that the increased velocities close to the cylinder is the predominant factor of run-up heights, in which the velocity head is included. Eventually, the results indicate that the difference among the maximum normalized run-up heights of these support structures is smaller for lower wave steepness than those for high wave steepness. In contrast, it is shown that the difference among the wave loads of these foundations is larger for lower wave steepness than those for higher wave steepness. A modified run-up parameter is also obtained by means of numerical simulation and found that the decreased value of modified run-up parameter is accompanied with increased values of wave steepness and the maximum normalized run-up height.

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