Master Degree / Yüksek Lisans Tezleri
Permanent URI for this collectionhttps://hdl.handle.net/11147/3008
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Master Thesis Energy Interaction of Vertical Axis Wind Turbines Working in Pairs(01. Izmir Institute of Technology, 2023) Gencer, Özgür; Karadeniz, Ziya Hatan; 01. Izmir Institute of TechnologyThe position of wind turbines relative to each other is important in terms of the performance of the turbines. The experiments and CFD studies in the literature have shown that Vertical Axis Wind Turbines (VAWT's) have a higher energy production per unit of land used than Horizontal Axis Wind Turbines (HAWT's) and it is found that there is a performance improvement of the VAWT's when they are operated in pairs. In this thesis, CFD simulations of the H-type VAWT's working in pairs have been perpormed to investigate the energy interaction of the turbines. A standalone one-bladed VAWT was modelled based on the previous studies in the literature for the validation of the CFD methodology. Simulation parameters and simulation settings are compared with the reference study in the mesh independency analysis for four different mesh settings resulting in a deviation of up to %14, and in the time step sensitivity analysis for two different time steps corresponding to 0.25 and 0.5 degrees of azimuthal angle increments resulting in a deviation of up to %15. 1, 2, and 3 bladed stand-alone turbines are investigated to reveal the effect of the inter-turbine blade interaction on the energy output. A pair of co-rotating turbines configuration is analyzed at various Tip Speed Ratios (TSR) (1.7, 2.2, 3.3, 4.4) and at compared with the standalone VAWT for each configuration. The results of CFD simulations show that adding blades to the standalone VAWT results in a more stable moment coefficient, but it also leads to a decrease in the power coefficient at high TSRs. The co-located turbines cause flow disruption for the VAWTs working in pairs operating at unstable TSRs (<2), resulting in a performance reduction of up 13.5%. Increasing the distance between turbines minimize the negative effect of disruption and improves turbine performance. As the TSR increases to a stable operation, the existence of the second turbine affects the energy output of both turbines positively, with the highest performance increase of 46% observed at TSR 3.3 when the turbines were placed closest to each other at 3D. The positive effect of the neighbouring turbine decreases as the distance between the turbines increase and the impact of distance between turbines on performance vanishes for the dewnstream turbine at 8D.Master Thesis Vibration Analysis of a Giromill-Type Vertical Axis Wind Turbine(Izmir Institute of Technology, 2013) Akgüneyli, Melih; Yardımoğlu, Bülent; Yardımoğlu, Bülent; 03.10. Department of Mechanical Engineering; 03. Faculty of Engineering; 01. Izmir Institute of TechnologyVibration characteristics such as natural frequencies and mode shapes of Giromill-type vertical axis wind turbines (VAWTs) with different design parameters are studied by Finite Element Method (FEM). As design parameters, length of the blade, thickness of the blade and the support distance of the blade are considered. On the other hand, local wind characteristics are considered for aerodynamic calculations. The well known commercial software package, ANSYS, is used for finite element analysis. Aerodynamic loads and centrifugal forces are taken into account in calculating the natural frequencies. In order to see the interactions of the parameters of the VAWT, seven models are obtained by modification of model I which is a reference model. Vibration characteristics of all models are found. The obtained results are presented in tabular forms.