20kW級浮游式黑潮發電渦輪機轉子葉片設計之研究

Abstract

本文主要乃探討葉片類型於未來洋流發電之分析與設計應用，原型為浮游式黑潮發電渦輪機(Floating Kuroshio Turbine；FKT)之創新設計，其額定輸出功率為20kw，並將所設計之渦輪機與發電機進行匹配，並掌握其最後額定輸出功率。 20 kW級 FKT系統之初步構型之概估規格和主要尺寸如下，即翼形浮體採NACA0018斷面，弦長4米，翼展7.5米，包含發電機組及轉子葉片的平軸左右對轉雙渦輪機組，在每秒1.5米的入流速度下，每一機組發電額定功率為10kW，可容納直驅式永磁發電機的機艙外徑估計約為1.2米，以初估可達的整體目標效率0.3估計，葉片直徑約為5 米，雙機軸心相距約為7.5 米，銜接兩部渦輪機組的橫樑跨距約為6.3米、連結翼形浮體和渦輪機組的直柱高約3 米。 為求了解不同類型的葉片特性差異，本文比較了NACA66與NACA63-815兩種不同特性的翼型為葉片截面而設計。本文利用流體動力模擬分析軟體ANSYS-FLUENT，採用有限體積法探討其力學特性，比較不同類型葉片間特性與其對扭矩與輸出功率之影響，以模擬不同葉片設計所具備的潛在輸出功率，並與富田電機所規畫設計之直驅式發電機性能進行匹配，以期掌握葉片設計之方法及葉片性能。

In the present study, the design, analysis, and application of different types of blade of marine current turbine are investigated. The prototype of the innovative design of a 20kW Floating Kuroshio Turbine (FKT) with twin rotors proposed by the M&C Lab of NTU is adopted to study in the present paper. One of the purposes is to develop the rotor blade design method for the FKT to match the given characteristics of direct driving generator and confirm the rated power output of 10 kW can be obtained. In order to clarify the differences between the characteristics of two different types of blade, two airfoils of NACA66 and NACA63-815 based design are compared in the present study. The CFD software ANSYS-FLUENT is adopted to deal with the hydrodynamic characteristics of the designed blade, in which finite volume method is applied for the CFD calculations. The results indicate that even the rated power output can be reached by both two designs of NACA66 and NACA63-815 airfoil based blade, but in the conditions of low inflow speeds and low rotation rpm the different blade sections may show quite different performance. It means that the flow conditions and the loading characteristics of the matching generator should be treated carefully in the rotor design processes. The results also show that the risk of occurrence of cavitation for the NACA66 based blade is not high.