面對全球的自然資源消耗，以及減少碳排放量的環境保護趨勢，海洋能源為未來永續的重要發展目標之一，而水波獵能器在滿足日益增長的全球能源需求方面具有巨大潛力。本實驗室先前曾針對水波獵能器之數學分析、數值計算以及實際建置水波獵能器系統進行實驗研究，此實驗成功設計出以振盪浮體型系統為概念的水波獵能器，而最終實驗結果裝置轉換效率具有許多的改善空間，因此本研究主要的目標是利用數值模擬計算水波獵能器力學性質-附加質量並且改變機構參數和幾何參數進而提升水波獵能器轉換效率。
此研究中我們建置兩個模型: (a)模型一為數值水槽模型，我們在線性系統條件下驗證線性波理論和造波器理論並得到良好的驗證結果，且我們透過台灣中部沿海之海況與拖曳水槽中的波浪參數條件做無因次分析得到波浪入射波的參數範圍，再來利用改變無因次參數 得到不同福祿數 入射波的振幅; (b)模型二為水波獵能器模型，我們建立計算水波獵能器附加質量的方法，我們定義修正係數 來修正非線性效應的影響，得知隨著浮體振幅越小受到非線性效應的影響較少所以修正係數 會趨近於一，並且計算出附加質量和入射波頻率與浮體振幅之間的關係式，了解到浮體振幅越大附加質量越小和入射波頻率越大附加質量越小的現象，再來我們利用計算出的附加質量討論最佳阻尼係數，發現當波浪扮演給予能量角色的時候波浪阻尼係數會小於零，最後我們討論不同水波獵能器機構參數(c、kext )和機構尺寸(直徑D 、水面下深度Dw )對轉換效率的影響，以及我們比較實驗結果和本研究模擬結果，可以發現在相同WEC振幅的情況下，利用數值模擬得到的轉換效率為實驗結果的33.7倍數;調整機構參數、幾何參數得到轉換效率為實驗結果的420倍，了解到有效提升水波獵能器轉換效率的方式就是提升浮體直徑，可以加裝彈簧於系統同時改變浮體水面下深度讓系統滿足共振條件可以有效提升轉換效率。

To fulfill the global environmental protection requirements of carbon emission reduction, the use of renewable energy has to be increased. And water wave energy certainly is one important form of renewable energy worth further development. In our previous work, a prototype of water wave energy harvester was designed and constructed for experimental testing in the towing tank at NCKU. But the conversion efficiency still have much room for improvement. So, in the current stage we focus our work upon calculating the hydrodynamic characteristics of the wave energy converter (WEC) by numerical computations. And the goal is to understand how the mechatronics and geometrical parameters affect the power output of the WEC, so that its performance efficiency can be maximized by tuning such parameters. Specifically, two computational models are constructed in the present work. The first is the “numerical wave tank” (NWT) model. The purpose is to calculate the excited wave characteristics (such as frequency and amplitude) and to verify them by comparison with existing theoretical formulas. And in the second model a WEC is added in the NWT, so that the rigid-body motion and hydrodynamic characteristics of the WEC can be computed. It is found that m_a depends on the frequency of the wave and the amplitude of WEC. Meanwhile, as k increases, r decreases and asymptotes to unity. Then we compare the results of the experiment and the simulation results. We find that the conversion efficiency of the simulation results.is 420 times larger than the experimental results when the mechatronics and geometric parameters are “optimally” tuned. And the way to enhance the conversion efficiency of the WEC is to increase the diameter and decrease the submerged depth of the WEC when the system is out of resonance, or to increase the submerged depth to make the system resonate with the incoming wave.

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