並聯矩陣型風力發電風車效率之實驗

Abstract

本研究建立一個四顆風車矩陣並聯之二葉式沙柏扭式風車系統，將其安裝在一個開放環境中用以發電，並使用流體力學套裝軟體Fluent進行分析。本研究內容可分為兩大部分：其一為擋板對該系統之影響，而另一主題為電路二次測電池之加入對系統之研究。實驗中，在不同風速、風向與風車轉速的情況下，觀測周速比與其功率係數（Cp）和發電量的關係。最後，將所獲得之實驗結果與數值模擬進行比較分析。 由數值模擬結果顯示，擋板的加入有助於效率的提升。其中，無檔板之系統最大Cp值為0.262，發生在周速比0.8的情況下；而有檔板之系統最大Cp值則為0.270，亦發生在周速比0.8時，相差1.03倍。然而，兩系統最大差異發生周速比0.6時，相差1.16倍。由Cp值對周速比圖可知，檔板在低周速比時較能發揮其效果；當在高周速比情況下其效果不顯著。 另一方面，由實驗結果顯示，在開放環境的風速、風向與風車轉速變化極大，故藉由反覆量測以得到Cp與周速比之關係。實驗結果與模擬相同，擋板確實有助於效率的提升。此外，實驗顯示，電池於電路二次測的脫離，並無助於效率提升，卻造成電壓之不穩定。在未來展望中將提升風車發電效率，並連接予市電作更有效的利用。

This study establishes a four two-bladed Savonius wind rotors system in parallel matrix which is installed at an open field, to generate electric power. Moreover, It employs a computational fluid dynamics (CFD) software, Fluent, to analyze the flow fields and system performance. It can be separated into two sections: effect of curtain and effect of battery. The experiments detect various wind velocity, wind direction and rotational speed of wind rotors to observe the relationship between tip-speed ratio (TSR) and power coefficient (Cp). Finally, compare and analyze the results between experiment and numerical simulation. For the numerical simulate results, the maximum Cp value of system without curtain is 0.262 at TSR 0.8; the system with curtain is 0.270 at TSR 0.8 which is 1.03 times higher than system without curtain. However, the maximal difference is happened at TSR 0.6 which is 1.16 times higher than system without curtain. From Cp to TSR diagram know that the effect of curtain especially enhance performance at low TSR. On the other hand, the experimental results show that the wind velocity, wind direction and rotational speed of wind rotors have large fluctuation in open field. Therefore, we receive the relationship between Cp and TSR by repeating measuring. Same as the simulation results, curtain indeed improve the performance of system. Otherwise, the experiment of withdrawing battery at second side of circuit shows that battery is no help for progress system performance (Cp) but cause voltage oscillation. Look into the future; improve the power generated efficiency of wind rotor system and connect system to local grid to have more benefit utilize.