scholarly journals Evaluation of the Power-Law Wind-Speed Extrapolation Method with Atmospheric Stability Classification Methods for Flows over Different Terrain Types

2018 ◽  
Vol 8 (9) ◽  
pp. 1429 ◽  
Author(s):  
Chang Xu ◽  
Chenyan Hao ◽  
Linmin Li ◽  
Xingxing Han ◽  
Feifei Xue ◽  
...  
Keyword(s):  
Wind Speed ◽  
Power Law ◽  
Atmospheric Stability ◽  
Extrapolation Method ◽  
Speed Ratio ◽  
Stability Conditions ◽  
Classification Methods ◽  
Average Value ◽  
Different Types ◽  
Stability Classification

The atmospheric stability and ground topography play an important role in shaping wind-speed profiles. However, the commonly used power-law wind-speed extrapolation method is usually applied, ignoring atmospheric stability effects. In the present work, a new power-law wind-speed extrapolation method based on atmospheric stability classification is proposed and evaluated for flows over different types of terrain. The method uses the wind shear exponent estimated in different stability conditions rather than its average value in all stability conditions. Four stability classification methods, namely the Richardson Gradient (RG) method, the Wind Direction Standard Deviation (WDSD) method, the Wind Speed Ratio (WSR) method and the Monin–Obukhov (MO) method are applied in the wind speed extrapolation method for three different types of terrain. Tapplicability is analyzed by comparing the errors between the measured data and the calculated results at the hub height. It is indicated that the WSR classification method is effective for all the terrains investigated while the WDSD method is more suitable in plain areas. Moreover, the RG and MO methods perform better in complex terrains than the other methods, if two-level temperature data are available.

The atmospheric turbulence characteristics in a diurnal cycle

2020 ◽  
Vol 34 (14n16) ◽  
pp. 2040109
Author(s):  
Yi-Lei Song ◽  
Lin-Lin Tian ◽  
Ning Zhao
Keyword(s):  
Wind Speed ◽  
Diurnal Cycle ◽  
Wind Shear ◽  
Atmospheric Stability ◽  
Atmospheric Flow ◽  
Eddy Simulation ◽  
Mean Wind Speed ◽  
Engineering Models ◽  
Wind Characteristics ◽  
Stability Classification

During a whole-day period, profiles of mean wind speed, wind shear and turbulence level shows great variability due to continuously varying atmospheric stability. Clearly understanding the spatial and temporal behaviors of the atmospheric wind flow is of great importance for science purposes. Large-eddy simulation (LES) technique is employed here to reproduce the evolution of atmospheric flow during a diurnal cycle. With the obtained LES results, wind characteristics in terms of wind speed, wind shear, turbulence intensity and turbulent kinetic energy can be examined referring to the stability classification. Besides, wind profiles obtained using currently available engineering models are also included for comparison. Disparities between the model predictions and the LES results illustrate that the standard engineering models cannot well capture the wind characteristics driven by the varying atmospheric stability solely, and a further improvement in models is highly needed.

scholarly journals DETERMINING VERTICAL WIND SPEED PROFILE IN THE ATMOSPHERIC LIMIT LAYER ON THE OUAHIGOUYA SITE IN BURKINA FASO.

2021 ◽  
Vol 10 (1) ◽  
pp. 94-105
Keyword(s):  
Wind Speed ◽  
Burkina Faso ◽  
Power Law ◽  
Vertical Profile ◽  
Atmospheric Stability ◽  
Vertical Wind ◽  
Night Time ◽  
Wind Speed Profile ◽  
Log Linear ◽  
Annual Scale

The properties of the vertical profile of the wind speed on a monthly and annual scale at the Ouahigouya site belonging to the Sahelian climatic zone in Burkina Faso were explored in this study. To do this, wind speed and temperature data at 10 m above ground and NASA satellite data at an altitude of 50 m in the atmospheric boundary layer were used over a period of ten years. From the theory of Monin-Obukhov, the logarithmic law and the power law made it possible to develop the variation of wind speed with altitude taking into account the conditions of atmospheric stability. According to statistical performance indicators, it has been observed that the vertical profile of the wind speed adjusted according to the power law and the log-linear law corresponds to the measurements. Regarding the state of stability of the atmosphere, we note that it is generally unstable from 10:00 a.m. to 6:00 p.m. and stable during other times of the day. The annual average wind shear coefficients during the convective and night time diurnal cycle are evaluated at 0.67 and 0.7, respectively. From the power law, the values of the shear coefficients, the average vertical profile on a monthly and annual scale of the wind was obtained by extrapolation of the wind data measured at 10 m from the ground. This study is the first of its kind in this area. To assess the wind resource available on the Ouahigouya site, investors can directly use the vertical wind profile based on the power law for an altitude between 10 and 50 m.

scholarly journals Experimental Study of Wind Booster Addition for Savonius Vertical Wind Turbine of Two Blades Variations Using Low Wind Speed

2019 ◽  
Vol 125 ◽  
pp. 14003
Author(s):  
Eflita Yohana ◽  
MSK. Tony Suryo U ◽  
Binawan Luhung ◽  
Mohamad Julian Reza ◽  
M Badruz Zaman
Keyword(s):  
Wind Speed ◽  
Wind Energy ◽  
Wind Turbine ◽  
Vertical Axis ◽  
Vertical Wind ◽  
Speed Ratio ◽  
Vertical Axis Wind Turbine ◽  
Tip Speed Ratio ◽  
Average Value ◽  
Low Wind Speed

The Wind turbine is a tool used in Wind Energy Conversion System (WECS). The wind turbine produces electricity by converting wind energy into kinetic energy and spinning to produce electricity. Vertical Axis Wind Turbine (VAWT) is designed to produce electricity from winds at low speeds. Vertical wind turbines have 2 types, they are wind turbine Savonius and Darrieus. This research is to know the effect of addition wind booster to Savonius vertical wind turbine with the variation 2 blades and 3 blades. Calculation the power generated by wind turbine using energy analysis method using the concept of the first law of thermodynamics. The result obtained is the highest value of blade power in Savonius wind turbine without wind booster (16.5 ± 1.9) W at wind speed 7 m/s with a tip speed ratio of 1.00 ± 0.01. While wind turbine Savonius with wind booster has the highest power (26.3 ± 1.6) W when the wind speed of 7 m/s with a tip speed ratio of 1.26 ± 0.01. The average value of vertical wind turbine power increases Savonius after wind booster use of 56%.

Further Investigation upon the Water Movements in the English Channel. Drift-Bottle Experiments in the Summers of 1927, 1928 and 1929, with Critical Notes on Drift-Bottle Experiments in General.

1930 ◽  
Vol 17 (1) ◽  
pp. 241-275 ◽  
Author(s):  
J. N. Carruthers
Keyword(s):  
Wind Speed ◽  
North Sea ◽  
English Channel ◽  
The North ◽  
Different Types ◽  
The North Sea ◽  
The Common ◽  
Relationship Of ◽  
Great Simplicity ◽  
Simple Surface

In July–August of three different years common surface-floating bottles were set adrift at International Station E2 (49° 27' N.—4° 42' W.). With them, various types of drag-fitted bottles were also put out. The journeys accomplished are discussed, and the striking differences as between year and year in the case of the common surface floaters, and as between the different types in the same year, are commented upon in the light of the prevailing winds. An inter-relationship of great simplicity is deduced between wind speed and the rate of travel of simple surface floating bottles up-Channel and across the North Sea from the results of experiments carried out in four different summers.

Features Extraction and Classification Methods for Automatic Selection of Two Different Types of Paint for Automotive Parts

2021 ◽  
Author(s):  
Deborah Martínez ◽  
Rafael Guzmán-Cabrera ◽  
Daniel A. May-Arrioja ◽  
Iván Hernández-Romano ◽  
Miguel Torres-Cisneros
Keyword(s):  
Features Extraction ◽  
Classification Methods ◽  
Automatic Selection ◽  
Different Types ◽  
Automotive Parts ◽  
Selection Of

Design and performance evaluation of vertical axis wind turbine for wind energy harvesting at railway

2021 ◽  
Vol ahead-of-print (ahead-of-print) ◽  
Author(s):  
Hashwini Lalchand Thadani ◽  
Fadia Dyni Zaaba ◽  
Muhammad Raimi Mohammad Shahrizal ◽  
Arjun Singh Jaj A. Jaspal Singh Jaj ◽  
Yun Ii Go
Keyword(s):  
Wind Speed ◽  
Energy Harvesting ◽  
Wind Energy ◽  
Wind Turbine ◽  
High Speed ◽  
Vertical Axis ◽  
Speed Ratio ◽  
Vertical Axis Wind Turbine ◽  
Modeling Tools ◽  
Content Type

PurposeThis paper aims to design an optimum vertical axis wind turbine (VAWT) and assess its techno-economic performance for wind energy harvesting at high-speed railway in Malaysia.Design/methodology/approachThis project adopted AutoCAD and ANSYS modeling tools to design and optimize the blade of the turbine. The site selected has a railway of 30 km with six stops. The vertical turbines are placed 1 m apart from each other considering the optimum tip speed ratio. The power produced and net present value had been analyzed to evaluate its techno-economic viability.FindingsComputational fluid dynamics (CFD) analysis of National Advisory Committee for Aeronautics (NACA) 0020 blade has been carried out. For a turbine with wind speed of 50 m/s and swept area of 8 m2, the power generated is 245 kW. For eight trains that operate for 19 h/day with an interval of 30 min in nonpeak hours and 15 min in peak hours, total energy generated is 66 MWh/day. The average cost saved by the train stations is RM 16.7 mil/year with battery charging capacity of 12 h/day.Originality/valueWind energy harvesting is not commonly used in Malaysia due to its low wind speed ranging from 1.5 to 4.5 m/s. Conventional wind turbine requires a minimum cut-in wind speed of 11 m/s to overcome the inertia and starts generating power. Hence, this paper proposes an optimum design of VAWT to harvest an unconventional untapped wind sources from railway. The research finding complements the alternate energy harvesting technologies which can serve as reference for countries which experienced similar geographic constraints.

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