The Effect of The Geometry of Bio-inspired Fin on Oscillating Propulsion System

• Main Authors: Tzu-hung Huang, 黃子鴻
• Other Authors: Jeng-Horng Chen
• Format: Others
• Language: zh-TW
• Published: 2008
• Online Access: http://ndltd.ncl.edu.tw/handle/37833135568955412520

碩士 === 國立成功大學 === 系統及船舶機電工程學系碩博士班 === 96 === In the field of fluid mechanics, bio-inspired propulsion is important.The main purpose of this thesis is to investigate the possible application of bio-inspired propulsion in ships. Therefore, we study the propulsion method of bio-inspired fin by investigating the effect of the changes of geometry of fin to thrust trend. In our experiment, we define thin-triangle fin system. According to the changes of geometry, we compare the thrust trend of fin by using NBR rubber as the material of fin. We design one oscillation propulsion system that makes the fins oscillating in the sine wave form, and then measure fin thrust trend by strain gages measure system. As for the items of our experiment, we investigate the relationship of three types of fin geometry in condition of the same oscillate angles and different amplitude and in condition of the same amplitude and different angles.Meanwhile we use flow visualization to analyze the working mechanism of fin. In the oscillation method of fin, the importance of sway is greater than that of yaw. In the analysis of flow visualization, we can compare the trends of oscillation velocity, position, and fin thrust. We argue that the main thrust trend of fin comes from the oscillation of model. The analysis of FFT can help us confirm that the frequeucy of the maximum power of fin is the twice of swinging period.