Performance prediction of darrieus type vertical axis wind turbines using numerical simulations

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Tezin Türü: Yüksek Lisans

Tezin Yürütüldüğü Kurum: Orta Doğu Teknik Üniversitesi, Mühendislik Fakültesi, Makina Mühendisliği Bölümü, Türkiye

Tezin Onay Tarihi: 2014

Öğrenci: FAZIL SELÇUK GÖMEÇ

Danışman: CÜNEYT SERT

Özet:

Flow over Darrieus type straight-bladed vertical axis wind turbines (VAWT) with NACA 0021 blade profile is simulated using ANSYS Fluent software. SST k- turbulence model is used for the two-dimensional, unsteady simulations. Wind speed is taken as 7 m/s and part of the problem domain including the rotating blades is modeled using the sliding mesh technique. Effects of boundary layer mesh parameters, time step and convergence tolerance on the solution accuracy are investigated with carefully designed runs. Performance of VAWTs with 2 and 3 blades, which are designed to have the same solidity ratio, are compared at different tip speed ratios. Instantaneous flow patterns of unsteady flow fields are analyzed by examining velocity and pressure contours. Start-up performance, which is known to be critical for Darrieus turbines, is investigated with special care and the effect of number of blades to this issue is studied.