| Summary: | 碩士 === 國立臺灣大學 === 工程科學及海洋工程學研究所 === 105 === Waves are inevitable environmental factor to all marine structures. In the present study, we are going to study wave exciting forces and moment acting on a Floating Kuroshio Turbine (FKT) when long waves propagate over it. FKT will have corresponding motion responses due to the wave exciting forces and moment. In general, FKT needs to face the challenge when weather is severe. Long waves may make FKT do some violent movement, these movements will affect the performance and reduce service life of FKT. Therefore, we are going to analyze the wave exciting forces and moment, and make preliminary evaluation of the movements due to these forces and moment.
In the present study, the CFD software ANSYS FLUENT is used for dealing with the hydrodynamic problems. To simulate the situation that FKT under waves, we add different wavelength and wave height keeping wave slope constant at the inlet, and then calculate the wave exciting force in both x and y direction as well as moment in z direction when FKT working at the depth of 25 meters. Finally use Fast Fourier Transfer to get the amplitude of wave exciting forces and moment, and analyze the movement made by them. We will also calculate the pitch moment and evaluate the corresponding pitch motion. After that, we will change the depth of FKT, make it to the depth of 10 and 40 meters and compare the results to clarify the variation with depth.
The results show that the longer the wavelength or the higher the wave height will make the wave exciting forces and moment larger, and it is obvious that when FKT comes close to free surface, it will also enhance the forces and moment. Therefore, FKT should go deeper to avoid the large amplitude exciting forces and moment when long waves are coming. As a future work, the CFD calculated wave exciting forces and moment may introduced into OrcaFlex as external forces to simulate the motions of FKT with mooring line due to the combining influences of waves and current.
|
|---|
