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  • Küçük Resim
    Öğe
    Determination of Ambient Turbulence Intensities for Stratified Atmospheric Flow
    (POLISH ACAD SCIENCES INST PHYSICS, 2018-07) Yazıcıoğlu, Hasan; Kara, Tolga; Özbek, Muammer
    The purpose of this study is to develop a numerical methodology which will allow the user to generate ambient turbulence intensities with respect to ambient wind speed for various flow conditions over completely flat terrain. The wind characteristics to be used in the analyses will be directly acquired by wind turbine sensors and measurement tower. The main objective of the work is to show that ambient and wake turbulence levels can be well presented with the developed methodology. The time resolution can be easily adjusted by the user. The developed framework has been validated with the nacelle and rotor effective wind speed model based turbulence intensity levels for all defined atmospheric stratification conditions. It is clear that the wake propagation is stimulated quite accurately and dissipation of the wake depends on the wake model in terms of deficit. The results have shown very good consistency with various ambient conditions.
  • Küçük Resim
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    Estimation of Ambient Turbulence Intensity over Complex Terrain
    (POLISH ACAD SCIENCES INST PHYSICS, 2018-07) Kara, Tolga; Yazıcıoğlu, Hasan; Özbek, Muammer; Tunç, Kerim Mehmet Murat
    The aim of the present study is to develop and validate a framework that can handle with ambient flow modeling of operational wind farms over complex terrain. The developed framework estimates the ambient turbulence intensities, which affect the fatigue loads, energy yields and machinery failures, with respect to several incoming flow parameters such as ambient wind speed, altitude and slope angle. Model has been validated with ambient normal turbulence intensities of IEC-61400 standards and reference speed-up models for representative incoming flow conditions, terrain slope angle and altitude based on two wind turbines in the same row that are in the wake of each other for two specific wind direction. The comparison shows fair agreement with the modeled ambient turbulence intensities.
  • Küçük Resim Yok
    Öğe
    Simulation of electricity generation by marine current turbines at Istanbul Bosphorus Strait
    (Pergamon-Elsevier Science Ltd, 2016) Yazicioglu, Hasan; Tunc, K. M. Murat; Ozbek, Muammer; Kara, Tolga
    In this work, several simulations and analyses are carried out to investigate the feasibility of generating electricity from underwater sea currents at Istanbul Bosphorus Strait. Bosphorus is a natural canal which forms a border between Europe and Asia by connecting Black Sea and Marmara Sea. The differences in elevation and salinity ratios between these two seas cause strong marine currents. Depending on the morphology of the canal the speed of the flow varies and at some specific locations the energy intensity reaches to sufficient levels where electricity generation by marine current turbines becomes economically feasible. In this study, several simulations are performed for a 10 MW marine turbine farm/cluster whose location is selected by taking into account several factors such as the canal morphology, current speed and passage of vessels. 360 different simulations are performed for 15 different virtual sea states. Similarly, 8 different configurations are analyzed in order to find the optimum spacing between the turbines. Considering the spatial variations in the current speed within the selected region, the analyses are performed for three different flow speeds corresponding to +/- 10% change in the average value. For each simulation the annual energy yield and cluster efficiency are calculated. (C) 2015 Elsevier Ltd. All rights reserved.