DESIGN AND ANALYSIS OF THE FLOATING KUROSHIO TURBINE BLADES

設計與分析浮游式黑潮洋流渦輪機葉片

The most common devices used for extracting the ocean current energy are the current turbines. Most people use the wind turbine blade design methods for the horizontal axis current turbine design; however, the current turbines operate in the water, and their physical behaviours are more like marine propellers. In this paper, two turbine blade design procedures are adopted. The first design procedure is similar to the propeller designs, and the second design procedure is to use Genetic Algorithm and boundary element method (BEM) to find a geometry which can provide the maximum torque. After completing the designs, hydrodynamic performances of the marine current turbine are then computed and analysed by the potential flow BEM and the viscous flow RANS method. The computational results show the geometries designed by the presented procedures can not only satisfy the hydrodynamic design goal, but also predict the delivered power very close to the experimental data. After the blade performance meets the design target, the performances of designed 20kw floating type Kuroshio turbine including the floating body at different operation conditions are demonstrated in the paper. Also, the structural strength of the turbine blade is computed by FEM, and the results are evaluated to see if the design complies the rule requirements. 最常用於擷取洋流蘊藏能量的機器就是洋流渦輪機，有關洋流渦輪機葉片的設計，風車葉片的設計方法是最多人使用的，然而，由於洋流渦輪機是在水中運作，事實上，其物理特性與船用螺旋槳更為接近。本文展示一水平軸洋流渦輪機葉片幾何之設計方法，此設計方法首先即應用與船用螺槳設計方法類似的方法進行設計，其次，利用基因演算法結合勢流邊界元素法改進渦輪機葉片幾何的設計。完成設計後，再應用勢流邊界元素法與黏性流方法分析設計出洋流渦輪機葉片的性能與流場。所設計的葉片，除了滿足設計目標，與實驗量測結果也相當接近。論文中並展示整體20千瓦浮游式黑潮洋流渦輪機的性能，同時，檢視在不同狀況下渦輪機的性能。最後，論文並應用有限元素法計算葉片的強度，以評估是否合乎法規的要求。