WoS İndeksli Yayınlar Koleksiyonu / WoS Indexed Publications Collection
Permanent URI for this collectionhttps://hdl.handle.net/11147/7150
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Conference Object The Effect of Permanent Magnet Location on The Performance of Ferrofluid Based Spncml(Begell House, inc, 2022) Bozkir, Selim Can; Karadeniz, Ziya Haktan; Cobanoglu, Nur; Doganay, Serkan; Karadeniz, Ziya Haktan; Turgut, Alpaslan; 03.06. Department of Energy Systems Engineering; 03. Faculty of Engineering; 01. Izmir Institute of TechnologyFerrofluids are suspensions of ferromagnetic nanoparticles (iron, cobalt, nickel, magnetite, hematite, etc.) dispersed in non-magnetic base fluids. They have application potential in many fields due to the tunable thermophysical properties and the manipulation capability of the ferromagnetic nanoparticles under the influence of an external magnetic field. This numerical study investigates the effect of external magnetic field location on the performance of ferrofluid-based single phase natural circulation mini loop (SPNCmL) in which the driving mechanism is resulting buoyancy forces of density gradient caused by temperature difference. Since the working fluid exhibits higher magnetization at low temperatures, effects of the magnetic field have been investigated for the low-temperature side of the SPNCmL by placing a permanent magnet at the cooling-end outlet and heating-end inlet. The steady 3D numerical model was developed in the COMSOL Multiphysics by coupling three different physics: magnetic field (no current), heat transfer in fluid, and laminar flow. The performance of the SPNCmL working with water-based Fe3O4 ferrofluid under an external magnetic field was evaluated in terms of the maximum temperature (T-max), the temperature difference between heater inlet and outlet (Delta T-heater), the effectiveness (epsilon), and the flow distribution. In addition, the magnetic field effect on the fluid flow was visualized by velocity and the temperature distributions at the critical cross-sections.Article Citation - WoS: 1Citation - Scopus: 1Numerical and Experimental Investigation of Aspect Ratio Effect on Aerodynamic Performance of Naca 4415 Airfoil Section at Low Reynolds Number(Assoc Mechanical Engineers Technicians Slovenia, 2025) Uemuetlue, Hatice Cansu Ayaz; Karadeniz, Ziya Haktan; Kiral, Zeki; Karadeniz, Ziya Haktan; 03.06. Department of Energy Systems Engineering; 03. Faculty of Engineering; 01. Izmir Institute of TechnologyIn this study, the effect of aspect ratio on the aerodynamic coefficients is investigated for a NACA 4415 airfoil profile. Four different aspect ratios which are 3, 5, 7, and 9 are evaluated with the computational fluid dynamics (CFD) simulations and the experiments. The CFD studies are performed using a threedimensional (3D) computational domain and by using the k-omega shear stress transport (SST) turbulence model for turbulence calculations. The measurements of the aerodynamic forces are carried out in open jet type wind tunnel using a three-component balance. CFD and experimental studies are performed at angles of attack from 0 degrees to 25 degrees and Reynolds number 85<middle dot>103. The results show that as the aspect ratio increases, separation points move towards the leading edge of the airfoil and the stall angle reduces. Furthermore, it is observed that the lift coefficients increase with the increasing aspect ratio. The results obtained indicate that there is a harmony between the experimental data and the CFD solutions.Article Citation - WoS: 1Citation - Scopus: 1Investigation of Flow and Heat Transfer Performance of Gyroid Structure as Porous Media(Turkish Soc Thermal Sciences Technology, 2024) Karadeniz, Ziya Haktan; Karadeniz, Ziya Haktan; 03.06. Department of Energy Systems Engineering; 03. Faculty of Engineering; 01. Izmir Institute of TechnologyThere are active and passive methods used to improve heat transfer. One of the passive methods is utilising porous media with high heat transfer surface area. Porous media are divided into two groups: regular and irregular structures. One of the regular structures is triply periodic minimal surfaces (TPMS), which have been studied quite frequently recently. In this study, heat transfer and flow analysis of a Gyroid geometry, one of the most used TPMS in the literature, is investigated numerically considering the conjugate heat transfer conditions. A single porosity is considered (epsilon = 0.6), and aluminium, ceramic and PLA are selected for the heat exchanger material to examine the temperature change in the heat exchanger. To understand the different flow characteristics, Reynolds numbers are assumed to be 19.12, 95.61 and 172.09. The fluid inlet temperature is assumed to be constant at 298.15 K, and the initial temperature of the heat exchanger is assumed to be constant at 278.15 K to be consistent with the regenerative heat recovery temperature difference in ventilation standards. Nusselt numbers under different operating conditions are compared, and it is the ceramic material with low thermal diffusivity is at the highest level despite its low thermal conductivity. At the highest Reynolds number, it provided approximately 6% better heat transfer than the aluminium heat exchanger.