報告書番号

N08018

タイトル（和文）

複雑地形上での適切な風車選定のための風の乱れ評価―数値流体解析を活用した乱流強度評価法の提案―

タイトル（英文）

Prediction for wind fluctuation to properly select wind turbines over a complex terrain- Proposal to predict turbulence intensity with computational fluid dynamics -

概要 （図表や脚注は「報告書全文」に掲載しております）

複雑地形上に建設される風車の適切な選定に資するべく，数値流体解析（CFD）を用いた風速変動の乱流強度評価法を検討した．始めに当所が開発した既存のCFDコード4種類（3種類のLESコードと1種類のURANSコード）を取りあげ，波面上チャネル流れの乱流解析に関するベンチマークテストを行った．そして，すべてのコードが，波面に起因する平均風速場の歪を再現することを確認した．また，LESコードは，乱れ場の非等方性や非定常性も再現可能であることを明らかにした．次に，LESコードの一つを用いて，実際の複雑地形上の風力発電所周辺の非定常風況解析を行った．解析結果と観測値とを比較し，水平方向の解像度を50mに設定した場合，変動風速の高次モーメントやパワースペクトルについても，解析値は観測値とよく一致した．これらの結果を踏まえて，CFDコードを用いた乱流強度評価手法を取り纏めた．

概要 （英文）

For appropriate selections of wind turbines, which are built over a complex terrain, the estimation method for turbulent intensity of wind-speed fluctuations with a computational fluid dynamics (CFD) cods was developed. First, a benchmark simulation for the turbulent flow over a wavy wall with various CFD codes (LES codes and a URANS code) was carried out. All results for mean velocity fields by LES and URANS codes showed the good agreement with direct numerical simulation data. In addition, it was confirmed that the LES codes have a capability to evaluate non-isotropic and unsteady behavior near the wavy wall, while such behavior especially in the outer layer can not be predicted by URANS code. Then, unsteady wind simulations for the near-neutral atmospheric surface layer over complex terrains were carried out with one of the LES code which is used in the benchmark simulation. Turbulence statistics including higher order moments and power spectra of velocity fluctuations were compared with observations, and it was confirmed that the simulation with 50 meters horizontal resolution has a capability to predict unsteady wind field over a complex terrain, i.e., the predictions for vertical profiles of turbulence statistics and the power spectra of velocity fluctuation agree well with observations. Finally, the estimation for the turbulence intensity over a complex terrain with the observation and CFD code was developed.

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