本研究以自由入流的情況下，固定風速在1 m∙s^(-1)進行PIV實驗量測，改變不同的實驗參數，分別為在風洞的漸縮管前加裝木條、漸縮管前放置數支運轉的風扇、改變地面高度讓地面更靠近雷射光頁。主要在不同的影像解析度下進行分析，計算出各別的能量頻譜並進行探討，可以在能量頻譜中得出一斜率接近(-5)/3之斜直線，此斜率下之範圍稱作慣性子範圍(inertial subrange)。本研究之能量頻譜大致上有符合斜率為(-5)/3之趨勢，與Kolmogorov之理論相符，因此在本研究中得到驗證。
由本研究之結果可以發現，紊流擾動具有跨尺度的擾動特性，而在不同解析度下之能量頻譜，解析度越高越可以反映出頻率更高、波長更短、尺度更小的渦流，也可以發現，在低解度之結果相較高解度無法符合Kolmogorov所預測之理論斜率為(-5)/3。此外，從本研究中可以發現，在波長(λ) (單位：m)大於約為5×〖10〗^(-2) (m)的斜率大致接近Kolmogorov的斜率(-5)/3之趨勢，然而，波長小於約為5×〖10〗^(-2) (m)的直線斜率開始變陡，尤其在越高解析度越可以明顯觀察得到，因此，依本研究室之現有設備，量測紊流尺度的精準度大約至小為5×〖10〗^(-2) (m)。

In this study, in the case of free inflow, the PIV experimental measurement was carried out at a fixed wind speed of 1 m∙s^(-1) and different experimental parameters were changed. They are adding the wood in the contraction of wind tunnel , putting the fans in front of the contraction of wind tunnel, and changing the height of the ground to bring the ground closer to the laser sheet. These experimental results are mainly analyzed under different image resolutions and respectively calculate the velocity, turblence intensity, and energy specteum of the free inflow in the wind tunnel experiment. In the end, we can obtain an oblique line with a slope close to-5/3 in the energy spectrum, and the range under this slope is called Inertia subrange. The energy spectrum of this study generally following the slope of -5/3, which is consistent with Kolmogorov’s theory, so it’s verified in this study. Futhermore, it can be found from this study that at wavelength(λ)(unit:m) greater than about 5×〖10〗^(-2) (m) , the slope is roughly close to Kolmogorov’s slope of -5/3 trend, however, the slope of the oblique line with wavelenghs less than about5×〖10〗^(-2) (m)begins to become steeper, espeially at higher resolutions, the more obvious it can be observed. Therefore, according to the current equipment in this laboratory, the accuracy of measuring the turblence scale is about 5×〖10〗^(-2) (m).

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