此研究主要是利用眼鏡蛇探針(Cobra probe)針對本實驗室所設計的二、三、四葉縮尺風機擺設在紊流邊界層風洞內(在輪轂高度的來流風速為6.8m s^(-1)紊流強度為10%)來做尾流逐點量測，透過分析平均風速分布、紊流強度、動量通量等氣動力特性來了解尾流的結構。在這次的實驗中主要分為下列兩種狀況來進行: (1)風機在偏航角-20°、+20°及0°狀況下運作時量測其水平剖面(上視圖)，分析風機尾流的發展狀況。(2)風機在邊界層內針對其垂直剖面量測(側視圖)並分析尾流在邊界層內發展狀況。除了風洞實驗外，本研究利用葉片元素理論(BEM theory)預測在風機近尾流區內的風速分布並且與紊流(本次實驗)及均勻(資料取自呂紹棟(2017) [1])入流條件下風機下游X/D=1處的風洞實驗量測結果做比較。
根據實驗結果指出尾流區內的風速會有明顯的降低且在葉片尖端處紊流會有大量的增強，但這趨勢會隨著與風機的距離增加而逐漸的恢復，由於風機會從來流中吸取大量的風能導致尾流區內動量遠低於周圍的流場，故動量皆會往尾流區內遞補。而當風機在有偏航角的狀況下運轉時，尾流的分布會偏向一邊。而這些尾流統計結果的趨勢會隨著葉片數目的增加而有明顯的增強。此外可發現能量頻譜圖的結果會非常接近斜率為-5/3的慣性區間(Inertial subrange)。
從葉片元素理論所預估出來的風速值與紊流及均勻入流條件下風機下游X/D=1處的風洞實驗量測的比較結果可得知在1D位置時，均勻入流的狀況下結果與葉片元素理論的質較為相近，說明紊流入流狀況下損失的風速有恢復較快的現象，而葉片元素理論可以用來預測大約的近尾流區風速值。

An experiment was carried out to study complex turbulence in the wakes originated from stand-alone 2, 3 and 4-blade wind turbines placed in the turbulent boundary-layer wind tunnel (turbulence intensity of 10% at the hub height) with two conditions:(1) the measurements in the vertical plane, and (2) the measurements in the horizontal plane when the turbine works in +20°,-20° and 0° yaw angle conditions. The calibration-free Cobra Probe was used to measure the three instantaneous velocity components in the wakes from the stand-alone turbine. Turbulence key statistics are analyzed and presented, including time-averaged velocity, turbulence intensity, momentum flux, and power spectrum. Besides, we use the BEM theory to predict the streamwise wind velocity to compare with the results of the measurements at the downwind position X/D=1 in the turbulence (the data obtained from this experiment) and uniform incoming flow (the data duplicate from the reference, Lyu (2017)[1]).
The results of the measurements indicate that the distribution of time-averaged velocity declines immediately downstream of the turbine models and then recovers with the wake-wise direction. The turbulence intensity has a strong enhancement at the tip-levels in the near-wake region. Momentum flux demonstrates how the kinetic energy of the flow is transported to recover the velocity deficit in the wakes. In particular, the wakes of the statistics are deflected to the side when the turbine works in a yaw angle condition, and the maximum of the key turbulence statistics are in the four-blade turbine case. The plots of the energy spectrum from the results are close to the inertial subrange with a global slope of -5/3 to confirm further the measured device is reliable.
The comparisons of the prediction from the BEM theory and the measurements in the turbulence and uniform inflow conditions demonstrate that the wind velocity deficit recovers faster in the turbulence case because of the turbulence mixing, and the BEM theory can be used to predict the approximate value of the wind velocity in the near wake.

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