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    Investigation of power coefficient behaviors of the parabolic wind rotor due to its variable geometry parameters
    (International Journal of Renewable Energy Research, 2020) Abusannuga, H.; Özkaymak, M.
    This paper provides explanations and analysis of how the power coefficient (Cp) of the Parabolic wind rotor has been affected by changing its geometrical design parameters. The results were presented in the form of (Cp) curves as a function of tip speed ratio (?0). The aerodynamic mathematical mode called "multi-streamtube" was implemented. To determine the Cp(?0) of the Parabolic rotor, regardless of its engineering shape, a computer program has been prepared by using Microsoft Visual Basic. The geometrical design parameters covered in this study are rotor blades number (N), rotor height (h) or (2H), rotor diameter (2R) and chord line (C). Whereas, through these parameters a total of 57 configurations were utilized and adopted. Thus, this number of different designs was sufficient to identify the performance behaviors of the Parabolic wind rotor. Accordingly, the results indicated that increasing rotor height to diameter ratio (H/R) leads to a decrease in Cp over low tip speed ratio range for all values of solidity, ?, (NC/R) investigated. However, higher values of (H/R) result in a raise in Cp over high tip speed ratio range for values of (NC/R) less than 0.2 approximately. Thus, it seems that higher (H/R) values constitute an advantage for fast rotating rotors (low (NC/R) and high tip speed ratio). © 2020, International Journal of Renewable Energy Research.
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    The theoretical and experimental investigation of temperature and salinity gradients in salt gradient solar ponds
    (2005) Kurt, H.; Özkaymak, M.; Korhan, Binark, V.A.
    In this study, both experimental and theoretical investigations were carried out in order to determine whether sodium carbonate salt which has not been used up to now for establishing salinity gradients is suitable for establishing salinity gradient in Salt Gradient Solar Pond (SGSP) or not. The heat storage ability of a solar pond was also examined. For this purpose, a small scale pond in the laboratory conditions was constructed for the experimental work and also one dimensional mathematical model for the SGSP's heat and mass transfer was developed. Differential equations obtained through by the developed model were solved numerically using finite difference method. The experimentally and theoretically obtained results showed that in order to establish temperature gradient in the sodium carbonate solution pond, a salinity gradient with salinity of about 12 % needs established.
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    Whether the Darrieus Rotor with Straight-Blades or Curved-blades is the Best, in Terms of Aerodynamic Efficiency
    (Institute of Physics, 2022) Abusannuga, H.; Özkaymak, M.
    An essential part of any wind turbine system is the rotor because it is the component that is in direct contact with wind and converts its kinetic energy into mechanical power. Then, it can either use this mechanical power directly to run some machinery, or you can use it to run an electricity generator and get electricity. One such turbine which is ideal for small-scale applications is the Darrieus wind turbine. This turbine has two blade configurations, straight or curved. This study aims to figure out the influences of these two blade configurations on the aerodynamic performance of the wind turbine. The engineering geometric shape of a parabolic Darrieus rotor was selected with certain dimensions, in this study it called P-D, and then a straight blade Darrieus rotor was extracted from it, in this study it called S-D1, similar to that of a parabolic in terms of rotor diameter and rotor height values, number of blades, blade section length and its type. Thus, a geometric similarity was obtained between the two rotors in terms of height to diameter ratio value and solidity value. Another rotor called S-D2 was also extracted and it is similar to P-D in terms of blade length, which means that the parabolic blade is straightened. There is also a similarity in solidity, and therefore it can be said that the masses of the rotors P-D and S-D2 are equal. This is the methodology that was followed to make the comparison in terms of aerodynamic. This analysis is done by developing a computer program that is based on mathematical model called multi-stream tube which modified to apply on both configurations of Darrieus turbine. The straight-bladed configuration is the best, according to this study. © Published under licence by IOP Publishing Ltd.