應用船艏振動翼於波浪推進之船模實驗探討

Abstract

隨著燃油價格的高漲以及全球氣候變遷意識日漸增強，節能減碳早已成為國際關注之議題，並積極尋求如何提升能源使用效率，或再生能源利用以及各種節能的方法，而航運造船領域也不例外。所謂”師法自然”，如何從歷經演化競爭存活下來的生物獲得科技創新研發的啟發也成為一門”仿生學”的學問。在船舶海洋領域，科學及工程專家著眼於海洋迴游魚類如何以低耗能、高效率方式在海裡推進，長程迴游，希望透過了解仿生運動模式達到節能的效果，並將研究成果應用於船舶在實海域的航行，經過多年的研究發展出許多創新設計與裝置，並希望透過發展出的成果達到減少船舶阻力或提升推進效率，且具有節能減碳的效果。此外，也已有一些針對使用被動或主動振動翼來擷取波能以協助船舶推進方法的探索。 本實驗研究的目的即在於尋求可應用於一般商船的節能裝置，應用自航船模的水槽實驗探討在船舶船艏處裝置振動翼，利用船舶於波浪中航行時所引致的船體起伏運動，搭配振動翼主動繞其轉軸縱搖所形成之起伏-縱搖耦合運動，擷取波能直接用以輔助船舶在波浪中推進之可行性驗證，並釐清振動翼主動控制模式。 本實驗研究驗證了應用主動式縱搖振動翼對於輔助船舶於波浪中推進有正面之效果，只要振動翼的縱搖領先起伏相位角在適當範圍內，對於船舶於波浪中推進之速度提升及節能可有顯著的效果。

Scientists have found that marine mammals like dolphins and whales swim in high efficiency. Marine mammals may also swim across the ocean by using wave energy and converting it to thrust through proper control of their tail fin. Ships traveling in wave will get ship motions from wave energy. It’s considered to be feasible to find an efficient way to enhance the ship propulsion by extracting wave energy and converting it to useful propulsive thrust. Hence, many concepts of propulsion system using active or passive control of oscillating fin are investigated and applied. However, most of them are focused on small crafts but not on general merchant ships. In the present study, a pair of oscillating bow fin with NACA0016 section controlled actively in pitch are applied to a container ship travelling in head waves for validating its effectiveness. The oscillating fins are placed underneath the front part of the container ship model with bulbous bow. The experiments implement in two wavelength of regular head wave, measure the mean speed of the ship model in wave with controlling the phase angle between heaving and pitching motion of the oscillating bow fin. The target of these experiments is to change the phase angle between heaving and pitching of the oscillating bow fin motion, finding the range of phase angles which enhance the speed of the ship model in wave. These results are compared with the mean speed in wave without flapping the oscillating bow fin. The experimental results show that it’s effective to enhance the speed of the ship model and to save energy in wave propulsion by applying an oscillating bow fin as long as the phase angle between heaving and pitching motion of the fin is in the appropriate range.