A study of Ball Screw Type of Wave Energy Conversion System driven by the Floating body

  • 張 顥譯

Student thesis: Master's Thesis

Abstract

The main goal of the thesis is studying a wave energy conversion system with ball screw kits and its feasibility The reason why adopting the ball screw kits is that we take advantage of its high efficiency of more than 90% of transforming slow linear motion into fast rotary motion It can benefit the slow motion of the oscillating floating body at sea Based on panel method the three-dimensional pulsating source is first used for calculating the related hydrodynamics coefficients with respect to different drafts and frequencies and then these coefficients can be applied to simulate the motion of the floating body by the 4^th Runge-Kutta method in time domain The precision of the calculation for the vertical motion of the wave energy conversion system will influence the accuracy of power estimation Therefore the present study simulates three kinds of vertical motions including “Pure floating body” “Floating body - Ball screw kits” and “Floating body - Ball screw kits - Generator” and compares them with experimental results It is found that with the increase of the wave period during the experiment the motion of “Floating body with ball screw kits” would get larger in the same wave height It is quite different from the motion of “floating body” As a result we assume that there is a time-delay between ball screw kits and floating body due to damping of mechanical system and the duration of this time-delay depends on the length of the ball screw lead To overcome this unsynchronized problem relatively gentle waves are required for this system Besides for the proposed device the lead of ball screw will determine whether it is laborious device or not However the application of ball screw kits for wave energy conversion system faces a problem that due to the precision the mechanism is hardly in harmony with the floating body after processing and installation Thus we keep dedicating to the improvement of this system and its preliminary type Furthermore the optimal ball screw lead the stroke and the rotary plate are determined by simulating the motion of the device Also the numerical results are verified by the experiments
Date of Award2014 Sep 1
Original languageEnglish
SupervisorMing-Chung Fang (Supervisor)

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