Master Degree / Yüksek Lisans Tezleri
Permanent URI for this collectionhttps://hdl.handle.net/11147/3008
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Master Thesis Coupled Wake and Blockage Modelling for a Wind Farm(Izmir Institute of Technology, 2022) Bingöl, Ferhat; Bingöl, Ferhat; 03.06. Department of Energy Systems Engineering; 03. Faculty of Engineering; 01. Izmir Institute of TechnologyOne of the significant reasons for the power loss in wind farms is the wake effect. Therefore, the wake effect is crucial for designing a wind farm. However, only wake modeling is not sufficient to explain power losses. Wake is the turbulent, complex, and relatively weak flow behind the wind turbine. The wake effect is not required for the front row turbines in wind farms, and the wake model cannot be applied. It is assumed that the wind farm directly encounters the free stream wind speed. However, the blockage effect, also known as the induction zone effect, is observed at the front of the wind turbines. Due to this effect, the wind farm encounters a lower wind speed than the free-stream wind speed. This situation reduces the accuracy of the Annual Energy Production (AEP) calculation in wind farms. The motivation of this study is to obtain an improved coupled wake and blockage model that converges to the accurate SCADA data of a wind farm more than the wakeonly or blockage-only models. This study applies seven wake and six blockage models to the wind farm. The similarities and differences between the coupled models and the wind farm SCADA data and their reasons are discussed.Master Thesis Modelling of Pore Formation in Porous Materials(Izmir Institute of Technology, 2017) Ülker, Sevkan; Güden, Mustafa; Akdoğan, Yaşar; Güden, Mustafa; Akdoğan, Yaşar; 03.09. Department of Materials Science and Engineering; 03.10. Department of Mechanical Engineering; 03. Faculty of Engineering; 01. Izmir Institute of TechnologyThe purpose of this thesis is to model the expansion behavior of aqueous slurries. Foamed or cellular material made using such method is known, especially in the concrete industry. What appears to be lacking in the literature is the knowledge of pore formation and pore growth in inorganic particles based on aqueous slurry systems that result in the formation of cellular structures. The motivation of this study is to provide a scientific view in identifying and explaining the critical parameters that govern the pore growth and expansion of such slurry based systems. Bubble growth and pore formation are also studied experimentally. Experimental results are used to compare with the empirical study conducted by Kanehira at al. (Kanehira, et al., 2013), and mathematical modeling of pore formation plotted with Wolfram Mathematica software. Experimental procedure consists of three types of aluminum and calcium ratios which provide information about bubble growth and pore formation. These types are 50% aluminum – 50% calcium hydroxide (50/50), 70% aluminum – 30% calcium hydroxide (70/30), and 80% aluminum – 20% calcium hydroxide (80/20). According to the results of studies, mathematical modeling system consists of the pressure difference between the inside and outside of a spherical bubble as the driving force for defining growth. While aluminum ratio increases, bubble growth rate decreases due to release of hydrogen gases which affect bubble expansion phenomenon. In the experimental and mathematical modeling, 50/50 ratio has maximum bubble growth rate compared to 70/30 and 80/20 ratios. The results of experimental and mathematical modeling suggest that viscosity is a very significant parameter which controls the bubble growth rate.