The Experts below are selected from a list of 321 Experts worldwide ranked by ideXlab platform
Guorui Ren - One of the best experts on this subject based on the ideXlab platform.
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the analysis of Turbulence Intensity based on wind speed data in onshore wind farms
Renewable Energy, 2018Co-Authors: Guorui Ren, Jinfu Liu, Jie Wan, Yufeng GuoAbstract:Abstract Wind speed Turbulence Intensity is crucial for wind turbine structure design and aerodynamic loads calculation. In the study, the actual Turbulence Intensity observations are compared with the Normal Turbulence Model defined by IEC standard. The results show that the Normal Turbulence Model overestimates the Turbulence Intensity. A new Turbulence Intensity model is proposed based on the actual observations, which shows better performance than the Normal Turbulence Model. Then the variation pattern of Turbulence Intensity during a day is analyzed. The Turbulence Intensity exhibits obvious daily periodicity in two wind farms. Furthermore, the causes of daily periodicity are discussed and verified by the wind speed dataset 3. Finally, an improved time-varying Turbulence Intensity model is developed according to the daily periodicity.
Yufeng Guo - One of the best experts on this subject based on the ideXlab platform.
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the analysis of Turbulence Intensity based on wind speed data in onshore wind farms
Renewable Energy, 2018Co-Authors: Guorui Ren, Jinfu Liu, Jie Wan, Yufeng GuoAbstract:Abstract Wind speed Turbulence Intensity is crucial for wind turbine structure design and aerodynamic loads calculation. In the study, the actual Turbulence Intensity observations are compared with the Normal Turbulence Model defined by IEC standard. The results show that the Normal Turbulence Model overestimates the Turbulence Intensity. A new Turbulence Intensity model is proposed based on the actual observations, which shows better performance than the Normal Turbulence Model. Then the variation pattern of Turbulence Intensity during a day is analyzed. The Turbulence Intensity exhibits obvious daily periodicity in two wind farms. Furthermore, the causes of daily periodicity are discussed and verified by the wind speed dataset 3. Finally, an improved time-varying Turbulence Intensity model is developed according to the daily periodicity.
G. W. Rankin - One of the best experts on this subject based on the ideXlab platform.
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The role of Turbulence length scale and Turbulence Intensity on forced convection from a heated horizontal circular cylinder
Experimental Thermal and Fluid Science, 2007Co-Authors: David S K Ting, G. W. RankinAbstract:Abstract The effects of Turbulence integral length scale and Turbulence Intensity on the convective heat transfer rate from a heated circular cylinder in crossflow of air were investigated. An aluminium cylinder of diameter 50.8 cm (2″) and with uniform surface temperature was placed horizontally in a wind tunnel. The cylinder was subjected to a homogeneous, isotropic turbulent flow, which was generated using a perforated plate. The cylinder surface temperature was monitored and measured with five embedded thermocouples. Tests were conducted at a Reynolds number of 27,700, relative Turbulence Intensity, Tu from 2.9% to 8.3% and Turbulence integral length scale to cylinder diameter ratio, L / D from 0.50 to 1.47. For L / D = 0.78, heat transfer increased with increasing Turbulence Intensity, whereas for Tu = 6.9%, heat transfer decreased with increasing Turbulence length scale.
Mohamed Badaoui - One of the best experts on this subject based on the ideXlab platform.
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Stochastic modelling of wind speeds based on Turbulence Intensity
Renewable Energy, 2020Co-Authors: J. Pablo Arenas-lópez, Mohamed BadaouiAbstract:Abstract In this article, we propose a model of wind speed on a scale of seconds based on a parametrization of the Ornstein-Uhlenbeck (OU) process, that allows the characterization of wind Turbulence. The determination of the accurate parametrization of the OU process that best fits the standard deviation of the wind speed follows the physical principle of wind, which states a relationship of proportionality between Turbulence Intensity and mean wind speed. The approach addressed in this paper consists in defining the coefficients in the OU process capable to capture the real data properties. To validate the proposed model, a Turbulence Intensity analysis was performed on a set of wind speed data in seconds provided by NCAR/EOL. The parameters of mean wind speed and Turbulence Intensity are used to configure each resulting model. The best parametrization of the OU process is chosen by comparing the set of wind speeds in seconds and their characteristics, and is determined by a Turbulence Intensity analysis. Finally, the proposed methodology is applied to describe a set of mean wind speeds measured every 10 min from a specific location in Mexico.
Antonio Segalini - One of the best experts on this subject based on the ideXlab platform.
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A new formulation for the streamwise Turbulence Intensity distribution in wall-bounded turbulent flows
European Journal of Mechanics B-fluids, 2012Co-Authors: P. Henrik Alfredsson, Ramis Orlu, Antonio SegaliniAbstract:Abstract The distribution of the streamwise velocity Turbulence Intensity has recently been discussed in several papers both from the viewpoint of new experimental results as well as attempts to model its behavior. In the present paper numerical and experimental data from zero pressure-gradient turbulent boundary layers, channel and pipe flows over smooth walls have been analyzed by means of the so called diagnostic plot introduced by Alfredsson & Orlu [P.H. Alfredsson, R. Orlu, The diagnostic plot–a litmus test for wall bounded Turbulence data, Eur. J. Mech. B Fluids 29 (2010) 403–406]. In the diagnostic plot the local Turbulence Intensity is plotted as function of the local mean velocity normalized with a reference velocity scale. Alfredsson et al. [P.H. Alfredsson, A. Segalini, R. Orlu, A new scaling for the streamwise Turbulence Intensity in wall-bounded turbulent flows and what it tells us about the outer peak, Phys. Fluids 23 (2011) 041702] observed that in the outer region of the boundary layer a universal linear decay of the Turbulence Intensity independent of the Reynolds number exists. This approach has been generalized for channel and pipe flows as well, and it has been found that the deviation from the previously established linear region appears at a given wall distance in viscous units (around 120) for all three canonical flows. Based on these results, new empirical fits for the streamwise velocity Turbulence Intensity distribution of each canonical flow are proposed. Coupled with a mean streamwise velocity profile description the model provides a composite profile for the streamwise variance profile that agrees nicely with existing numerical and experimental data. Extrapolation of the proposed scaling to high Reynolds numbers predicts the emergence of a second peak of the streamwise variance profile that at even higher Reynolds numbers overtakes the inner one.
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A new formulation for the streamwise Turbulence Intensity distribution
Journal of Physics: Conference Series, 2011Co-Authors: P. Henrik Alfredsson, Ramis Orlu, Antonio SegaliniAbstract:Numerical and experimental data from zero pressure-gradient turbulent boundary layers over smooth walls have been analyzed by means of the so called diagnostic plot introduced by Alfredsson & Orlu [Eur. J. Fluid Mech. B/Fluids, 42, 403 (2010)]. In the diagnostic plot the local Turbulence Intensity is shown as a function of the local mean velocity normalized with a reference velocity scale. In the outer region of the boundary layer a universal linear decay of the Turbulence Intensity is observed independent of Reynolds number. The deviation from this linear region appears in the buffer region and seems to be universal when normalized with the friction velocity. Therefore, a new empirical fit for the streamwise velocity Turbulence Intensity distribution is proposed and the results are compared with up to date reliable high-Reynolds number experiments and extrapolated towards Reynolds numbers relevant to atmospherical boundary layers.
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A new formulation for the streamwise Turbulence Intensity distribution
Journal of Physics: Conference Series, 2011Co-Authors: P. Henrik Alfredsson, Ramis Orlu, Antonio SegaliniAbstract:Numerical and experimental data from zero pressure-gradient turbulent boundary layers over smooth walls have been analyzed by means of the so called diagnostic plot introduced by Alfredsson & Orlu [Eur. J. Fluid Mech. B/Fluids, 42, 403 (2010)]. In the diagnostic plot the local Turbulence Intensity is shown as a function of the local mean velocity normalized with a reference velocity scale. In the outer region of the boundary layer a universal linear decay of the Turbulence Intensity is observed independent of Reynolds number. The deviation from this linear region appears in the buffer region and seems to be universal when normalized with the friction velocity. Therefore, a new empirical fit for the streamwise velocity Turbulence Intensity distribution is proposed and the results are compared with up to date reliable high-Reynolds number experiments and extrapolated towards Reynolds numbers relevant to atmospherical boundary layers.
