Scopus İndeksli Yayınlar Koleksiyonu / Scopus Indexed Publications Collection
Permanent URI for this collectionhttps://hdl.handle.net/11147/7148
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Article Citation - WoS: 2Citation - Scopus: 3Air Density Calculation at High Altitude Locations for Wind Energy Use: the Alpines Validation(Taylor & Francis, 2023) Bingöl, FerhatAtmospheric air density has an essential role in the energy production of wind turbines. It is directly proportional to the power taken out from the airflow. The common practice at a planned wind farm location is to measure atmospheric parameters and calculate the air density as monthly and yearly averages based on the International Committee for Weights and Measures (CIPM). After that, the reference point is used to calibrate spatial data to study the siting of wind turbines at a large spatial domain of interest using an engineering method based on only temperature and elevation a.m.s.l. The engineering method is also employed with only temperature and elevation data when there are no pressure and relative humidity measurements. The point-to-spatial transformation is done through the simplified engineering formula, and it is known that the method is primarily valid up to (Formula presented.) a.m.s.l. Above these elevations, the engineering methods have a significant bias, up to (Formula presented.) error in estimating the air density. This bias leads to a substantial error in energy yield estimations. This study uses more than one in-situ measurement at high altitude locations to calibrate the engineering method at the Alpine Convention Perimeter. It aims to improve the calculation accuracy by calculating the pressure gradient within the region. It is found that the seasonal and yearly averaging errors can be improved by (Formula presented.) to (Formula presented.) in the air density calculation with the new approach. The method can be applied to other locations with similar conditions.Article Comparison of Length Scale Parameterization Methodologies(MDPI Multidisciplinary Digital Publishing Institute, 2020) Tuna, Faruk; Bingöl, FerhatAtmospheric stability has been studied for decades. There are several methodologies that evolved over the years. In this study, a special experimental meteorological mast that has been erected to a complex site has been used to calculate dimensionless Obukhov length (zeta), dimensionless momentum (phi m), and heat coefficients (phi h). The results are compared with the ones from average value approaches: Richardson number, flux-profile (F-P) relations, and wind shear exponent methods. The results show that the estimated zeta values, using the bulk Richardson number, get along well with the reference zeta within the neutral and stable regimes. F-P relations and wind shear exponent methods result in the best agreement for stable and neutral regimes. Nevertheless, average oriented methods are not reliable for the other regimes.Article Citation - WoS: 18Citation - Scopus: 20Comparison of Weibull Estimation Methods for Diverse Winds(Hindawi Publishing Corporation, 2020) Bingöl, FerhatWind farm siting relies on in situ measurements and statistical analysis of the wind distribution. The current statistical methods include distribution functions. The one that is known to provide the best fit to the nature of the wind is the Weibull distribution function. It is relatively straightforward to parameterize wind resources with the Weibull function if the distribution fits what the function represents but the estimation process gets complicated if the distribution of the wind is diverse in terms of speed and direction. In this study, data from a 101 m meteorological mast were used to test several estimation methods. The available data display seasonal variations, with low wind speeds in different seasons and effects of a moderately complex surrounding. The results show that the maximum likelihood method is much more successful than industry standard WAsP method when the diverse winds with high percentile of low wind speed occur.Article Citation - WoS: 5Citation - Scopus: 6A Simplified Method on Estimation of Forest Roughness by Use of Aerial Lidar Data(Wiley, 2019) Bingöl, FerhatIn the last decade, satellite-based measurements combined with local land cover information have produced datasets with a very detailed land cover description. CORINE Land Cover (CLC) dataset is owned and maintained by the European Environmental Agency (EEA) and published at the agency's website. Another remote sensing tool, developed in the same period, is the terrain LIDAR scanners with very high resolution and porosity information. In the current study, LIDAR scans of mainland Denmark with 0.4 m resolution were used to estimate the aerodynamic roughness of large forests, the borders of which were defined with the help of the CLC dataset. The results are compared with available in situ measurement results from the scientific literature. There was a generally good agreement between calculated and measured displacement height values but less so for aerodynamic roughness values due to the employed spatial averaging process. The results reveal a promising application that can be used for forest parameterization within modeling tools.