建置滑動轉軸式推拉板水動力行為評估之數值模式

A 2-D NUMERICAL MODEL FOR THE HYDRODYNAMIC BEHAVIORS OF A SLIDING BOTTOM HINGED FLAP WITH THE SPH METHOD

A Smoothed Particle Hydrodynamics (SPH) model was established to evaluate the hydrodynamic behaviors for a sliding bottom hinged flap (SBHF). The hydrodynamic behaviors were investigated primarily on rotating angle and sliding distance of a flap with regular wave trains of 7.8 cm in height and 1.56 s in period based on a model scale of 1:20 of typical wave conditions in winter monsoon seasons offshore northeastern Taiwan. Comparisons of the simulated rotating angles of present model with a non-sliding bottom-hinged flap (BHF) have shown reasonable agreements with a correlation coefficient of 0.98. The simulations have demonstrated a smaller averaged rotation of 4.18° at an averaged sliding distance of 0.09 m during a wave cycle. Comparisons of the flow fields and circulations near the flaps with BHF show that a SBHF could be easily driven with the incident waves and have the lower circulations than a bottom-hinged. For energy conversions, the SBHF had resulted in lower both reflection and transmission coefficients so that higher power could be extracted by a SBHF. 本論文應用光滑粒子水動力法建置評估滑動轉軸式推拉板之水動力行為，波浪條件採用台灣東北海域典型的年平均值，以1:20模型尺度轉換的7.8公分波高及1.56秒週期評估其滑動位移與轉動的角度。模式驗證顯示，當底部摩擦力增大產生不滑動現象時，與坐底式推拉板之旋轉角度可達0.98之相關係數，顯示此模式模擬具有合理的模擬結果。在案例模擬上，推拉板在波浪作用下，產生了4.18度的平均轉動角度與0.09公尺的平均位移。比較其流場與速度場發現，移動轉軸式的推拉板確實可較座底式推拉板減少渦度，且在能量擷取的評估上，也具有較高的擷取效率。