Master Degree / Yüksek Lisans Tezleri
Permanent URI for this collectionhttps://hdl.handle.net/11147/3008
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Master Thesis Model Design and Experimental Investigation of Floating Wind Turbine(01. Izmir Institute of Technology, 2022) Arıdıcı, Ali; Özkol, ÜnverFloating offshore wind energy has great potential (which constitutes almost 80% of total offshore wind energy) to meet electricity demand of the world at the same time to reach net-zero emission goal by 2050. Floating offshore wind turbines (FOWT) are able to achieve highest capacity factor since local effects of the offshore terrains are lesser. Thus, it receives stronger and more stable wind. On the other hand, combined hydrodynamic and aerodynamic forces with 6 degrees of freedom (DoF) bring unsteadiness and there- fore, challenges on FOWT design. Furthermore, significant rotational motions, particu- larly pitch motion, lead the turbine to transient state which can not be simulated through conventional numerical tools. Therefore, to understand the dynamics of the FOWT, it is necessary to conduct experimental studies to obtain results by considering all the param- eters. The main aim of the thesis is to investigate the dynamic response of the FOWT under the extreme wind and wave conditions. A 1/40 Froude-scaled version of the Northel POYRA P36/300 mounted on the spar-type floating platform was developed by colleagues as a part of TUBITAK (217M451) project. In this thesis, experimental studies were car- ried out in the wave flume with a wind nozzle in the hydraulic laboratory of IZTECH Civil Engineering Department. Atmospheric boundary layer (ABL) was scaled, and in- struments of the experiment were calibrated to characterize wind nozzle and wave maker, which are vital to obtaining reliable results. The wind nozzle was designed based on experimental data to reproduce correct Froude-scaled ABL.Master Thesis Wave Generation and Analysis in the Laboratory Wave Channel To Conduct Experiments on the Numerically Modeled Spar Type Floating Wind Turbine(01. Izmir Institute of Technology, 2020) Aktaş, Kadir; Özbahçeci, BergüzarThe oceans offer immense potential for harvesting sustainable wind energy, with stronger and steadier winds for locations further offshore. Since the feasibility of fixed-bottom offshore wind turbines decreases with increasing water depth, floating offshore wind turbines (FOWT) becomes a promising field of study. As part of a TÜBİTAK project (217M451) that investigates the dynamic performance of different FOWT designs under wind and wave loads, the necessary laboratory wave generation, analysis, and test set-up to conduct physical model experiments of a spar-type FOWT model is established in this study. An investigation of the wavemaker theory yielded that using first-order wavemaker solutions in the laboratory leads to the generation of spurious harmonic waves that do not appear in natural waves. Therefore, the second-order solutions are applied to the piston-type wave generator for a closer approximation of natural waves in laboratory conditions. A numerical model investigation of a reference spar-type FOWT is conducted to gain insights into spar design using ANSYS AQWA. The results indicate that the spar model dynamic responses are susceptible to low-frequency waves in pitch and surge degrees of freedom as its natural frequency lies in that region which further emphasizes the importance of generating laboratory waves using second-order wavemaker theory. Additionally, a spar-type floating platform is modeled at the 1/40 Froude scale, to use in the hydraulic model experiments. The wave measurement set-up is fully implemented and theoretically generated waves are measured for validation. In conclusion, regular and irregular wave generation and wave analysis in the time and the frequency domain could be possible in the wave channel of IZTECH Civil Engineering Hydraulic Laboratory.