Preliminary Study on an On-Shore OWC Incorporated with a Flapper

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簡歷

基本資料

Project title

Code/計畫編號

MOST104-ET-E019-006-ET

Translated Name/計畫中文名

岸基式OWC與推拉板結合之先期研究

Project Coordinator/計畫主持人

Yi-Chih Chow

Funding Organization/主管機關

National Science and Technology Council

Co-Investigator(s)/共同執行人

林鎮洲

Department/Unit

Department of Systems Engineering and Naval Architecture

Website

https://www.grb.gov.tw/search/planDetail?id=11275297

Year

2015

Start date/計畫起

01-01-2015

Expected Completion/計畫迄

01-12-2015

Co-Investigator(s)

Chen-Chou Lin

Bugetid/研究經費

888千元

ResearchField/研究領域

土木水利工程
資訊科學--軟體

"再生能源的有效開發為目前世界性重要的議題之一，相較於太陽能、風能，同屬於再生能源的海洋波浪能則具有非常大的潛力。波浪能的採集與轉換是透過波能轉換器(wave energy converter, WEC)來達成，而波能轉換器的型式眾多，其中的振盪水柱式(oscillating water column, OWC)與振盪衝擊式(oscillating wave surge converter, OWSC)皆為裝置於近岸(near-shore)或岸基式(on-shore)的著名型式。 OWC的原理為在一氣室中之海水面因波浪起伏而排擠或吸進空氣，此空氣之流動再驅動渦輪發電機來發電。表面上來看，壁面將大部分入射波反射回去，且雙向空氣渦輪機的效率不佳，才使得OWC的波能轉換效率不高。為了改善OWC的效率不彰問題，原計畫嘗試引入OWSC的概念，將OWC面向波浪之壁體改成一頂部轉軸(top-hinged)鐘擺式的推拉板體(flapper)，期待以高效率的方式來先行吸收大部分的波浪能，進而改善OWC的效率。我們先以WAMIT為核心的WEC-Sim軟體，來模擬單一頂部轉軸推拉板，發現其波能捕獲效能(或稱捕獲係數，capture factor，CF)並不如預期，因此當它與OWC結合後整體效能之提升可能也不如預期，反而大大增加系統的複雜度。因此後續研究我們改以OWC入口前兩側設置波浪導板(wave guide plate，WGP)的方式，實驗探討兩側WGP的開放角度在不同入射波條件與不同氣道阻尼情況下，對增加OWC的波能捕獲效能之間的關係。我們先透過影像處理分析技術獲得氣室內水面運動的數據，再以理論所推導出來的關係式求得CF，找到了最佳的WGP開放角度，以及CF超過1(繞射效應)的參數組合。研究中我們亦透過商用軟體FLUENT模擬之結果與實驗結果做一比對(無WGP)，以確認實驗結果與數值模擬結果二者的趨勢相符。整體而言，相同條件下數值模擬結果的CF值都大於實驗結果的CF值，兩種探討方法之數據變化趨勢大致相符。" "The working principle of the OWC is to use the vertical oscillation of the water surface due to waves to press air out of or suck air into a chamber through a turbine to generate electricity. From the appearance, the fact that the energy conversion efficiency of the OWC is not as high as one would expect is due to the reflection of large portion of the incident wave by the wetted wall of the OWC, and the low efficiency of the bi-directional air turbine. In order to improve the OWC’s efficiency, the original proposal was to introduce the concept of the OWSC in a way that the wall of the OWC facing incoming waves is replaced with a top-hinged flapper which highly-efficiently captures the major portion of the wave energy to improve the over-all efficiency of the OWC. We first use the WEC-Sim software with a WAMIT kernel as a basis to numerically simulate an isolated top-hinged flapper. It is found that the top-hinged flapper doesn’t have a capture factor as high as expected, resulting in a much more complex system when integrated with an OWC without the expected high benefit. Therefore, in the following research efforts, we use instead two wave guide plates (WGP) respectively installed at the left and right sides outside the OWC inlet, and experimentally investigate the relation of the open angle formed by these two guide plates to the wave capture capability of the OWC that leads to the optimum open angle. We use the techniques of image processing and analysis to obtain data of the kinematics of the water level in the chamber, and then convert them into the CFs with the formulas derived from the theory. In doing so, we’ve found the optimum open angle of WGPs and the parameter combination to yield CF > 1 (diffraction effect). We also use FLUENT to simulate the cases without WGPs installed and compare the results with that of the experiment to make sure that they are in the same trends."

Keyword(s)

波能轉換器
振盪水柱式
振盪衝擊式
推拉板
岸基式
效率
WEC-Sim
WAMIT
模型實驗
海洋能
再生能
wave energy converter
OWC (oscillating water column)
OWSC (oscillating wave surge converter)
flapper
on-shore
efficiency
WEC-Sim
WAMIT
model experiment
marine energy
renewable energy

DSpace CRIS

Preliminary Study on an On-Shore OWC Incorporated with a Flapper

基本資料

Description