LEE- Kıyı Bilimleri ve Mühendisliği-Doktora
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ÖgeCurrent and wave power derivations and their applications by using perturbation theory(Lisansüstü Eğitim Enstitüsü, 2022) Ulusoy, İsmail Can ; Erdik, Tarkan ; 724404 ; Kıyı Bilimleri ve MühendisliğiDue to the developments in both industry and technology over the last century, the need for energy resources continues to increase day by day. Although most of the energy needs are still met by fossil fuels, it should be kept in mind that fossil fuel resources are limited and negatively affect the environment. In addition, price fluctuations in fossil fuels adversely affect developing countries, causing them to sometimes have difficulties accessing energy. Thus, especially developing countries search for sustainable energy sources to reduce their energy imports. In developed countries, however, it is a different matter. Increasing environmental awareness creates public opinion against environmental pollution caused by fossil fuels since the gases released from burning fossil fuels harm both the environment and the health of living things. In particular, excessive carbon dioxide emissions change the gas balance in the atmosphere. In this context, it causes climate change, of which we have witnessed the impacts of in recent years, and accelerates this process. One of the most effective ways to eliminate or reduce the harmful effects of fossil fuels is to use clean and renewable energy sources. The leading clean and renewable energy sources are solar, wind, biomass, geothermal, and ocean energies. This thesis examines the current and wave energies, which are renewable ocean energy sources. The current energy is formed by tides, as well as the differences in water density and elevation. This study investigates the energy of stratified streams arising from the difference in water density. Unlike the classical method, the perturbation theory was used in examining current and wave energies. The primary reason for using the perturbation method is to consider the turbulence factor among the variables used to calculate the current and wave energies. Since the turbulence factor is not considered in classical method calculations, a lower amount of potential energy can be calculated. As a result of using the perturbation method, it is predicted that both more reliable and higher potential energy can be calculated. The turbulence factor of the velocity variable was taken into account in calculating the current energy using the perturbation theory. The classical method uses the equation P=1/2 ρV^3 to calculate the current power. In this equation, P is the current power, ρ is the water density, and V is the current velocity. In perturbation theory, on the other hand, the current velocity V is studied as two components: V=V ̅+V'. V is denoted as V ̅ : the average current velocity and V': perturbation term (turbulence component). The major difference between the perturbation theory and the classical method is the perturbation term. The turbulence factors of the wave period and the significant wave height are taken into account to calculate wave energy. The wave power is calculated with the formula P=0.49TH^2 in the classical method. In this equation, P: the wave power, T: the wave period, and H: the significant wave height. The turbulence factors of random variables T and H were also taken into account in the perturbation theory. Thus, it can be expressed as T=T ̅+T^' and H=H ̅+H^'. Here, T ̅ and H ̅ are the arithmetic means of the wave period and the significant wave height, respectively, and T^'and H^'are the perturbation terms of the wave period and the significant wave height. This thesis first includes literature studies on current and wave power. Then, both classical method formulas are given for current and wave power calculations, and equations are derived with the perturbation theory. The equations derived by the perturbation method are general ones and are arranged to adapt to the distribution parameters of the random variable to which the time series will fit. Therefore, after the moment of the distribution to which the random variable adjusts is known, the expected power value can be calculated by the perturbation method using the relevant data due to the following operations. After the current and wave power formulas are derived and presented, information about the study areas where the data set in which the related equations will be used is provided. Within the scope of this thesis, the energies of the upper current of the Dardanelles, the bottom current of the Dardanelles, the current of a location close to the north of the Bosphorus, and the wave energies at two stations in Mersin and Antalya regions were estimated. The current strength in the Dardanelles was examined for the first time in the literature within the scope of this thesis. Current rose was prepared first when examining the upper layer current of the Dardanelles. Afterwards, it was determined that the distribution in which the current velocity was compatible was found to fit the generalized gamma distribution, and the parameters of the relevant distribution were determined. By using the moment equations of the generalized gamma distribution function, current power formulas were derived by perturbation method. After deriving the current power formulas, the power of the upper layer current of the Dardanelles was estimated with the determined parameters of the generalized gamma distribution function. For bottom layer of the Dardanelles Strait, current rose was formed. Then, the parameters of the exponential distribution to which the current velocity conformed were obtained. By using the moment equation of the exponential distribution, the current power formulas were derived by the perturbation method. The power of the bottom layer of the Dardanelles Strait was estimated using the parameters of the exponential distribution by means of the derived equations. Current rose for current data in the area close to the northern part of the Bosphorus was prepared. Later, the current data were examined, and it was determined that the current velocities matched the log-Pearson type 3 distribution. Current power equations were derived using the log-Pearson type 3 distribution and the perturbation method. The current power in the region close to the northern part of the Bosphorus was estimated using the distribution parameters through the related equations. Two stations in Mersin and Antalya regions were selected to determine the wave power by the perturbation method. First, wave roses were prepared using the related wave data. Then, the data on the wave period and the significant wave height, which are the variables in the current power formula, were examined. As a result of the examination, it was determined that the wave period and significant wave height data were in accordance with the lognormal distribution. Wave power formulas were derived using both classical and perturbation methods using the lognormal distribution. The wave power was estimated using the derived equations and the parameters of the wave period and the significant wave height. In conclusion, the current and wave power estimations within the scope of this thesis were made with the perturbation approach, different from the classical method. The major difference between this approach and the classical approach is that this one takes into account the turbulence factor. As a result of the estimations, it was revealed that the perturbation approach provided a higher and more accurate potential energy estimation than the classical method.