Characteristics of the Mean Wind Speed Based on Field Measurement at Aizhai Bridge Gorge

2014 ◽  
Vol 521 ◽  
pp. 113-116
Author(s):  
Hong Xin Sun ◽  
Tao Yu ◽  
Xiu Yong Wang
Keyword(s):  
Surface Roughness ◽  
Wind Speed ◽  
Field Measurement ◽  
Bridge Site ◽  
Design Code ◽  
Average Wind Speed ◽  
Average Wind ◽  
Mean Wind Speed ◽  
The Mean ◽  
Fluctuating Wind

It is seriously different about characteristics of the mean wind speed between a deep gorge and plains, because of the deck of Aizhai bride to deep gorge bottom up to 335m. Characteristics of the mean wind speed in the deep gorge at the Aizhai bridge site are investigated based on field measurement using three 2D anemometers. The plan of field measurement was induced, and the wind speed, fluctuating wind speed and the 10min average wind speed with 10 days as a unit was analyzed. It if found that wind direction is basically consistent with the gorge toward. Based on the Wind-Resistant Design code, the surface roughness coefficients was fitted about 0.29, and very close to D class of the wind code.

scholarly journals Spatiotemporal Characteristics of Near-Surface Wind in Shenzhen

2020 ◽  
Vol 12 (2) ◽  
pp. 739 ◽  
Author(s):  
Cheng Liu ◽  
Qinglan Li ◽  
Wei Zhao ◽  
Yuqing Wang ◽  
Riaz Ali ◽  
...  
Keyword(s):  
Wind Speed ◽  
Wind Direction ◽  
Surface Wind ◽  
Prevailing Wind ◽  
Average Wind Speed ◽  
Near Surface ◽  
Average Wind ◽  
Prevailing Wind Direction ◽  
Seasonal Wind ◽  
The Mean

The spatiotemporal characteristics of near-surface wind in Shenzhen were investigated in this study by using hourly observations at 92 automatic weather stations (AWSs) from 2009 to 2018. The results show that during the past 10 years, most of the stations showed a decreasing trend in the annual mean of the 10 min average wind speed (avg-wind) and the mean of the 3 s average wind speed (gust wind). Over half of the decreasing trends at the stations were statistically significant (p < 0.05). Seasonally, the decrease in wind speed was the most severe in spring, followed by autumn, winter, and summer. The distribution of wind speed tends to be greater in the east and coastal areas for both avg-wind and gust wind. From September to March of the following year, the prevailing wind direction in Shenzhen was northerly, and from April to August, the prevailing wind direction was southerly. The seasonal wind speed distribution exhibited two different types, spring–summer type and autumn–winter type, which may be induced by their different prevailing wind directions. The analysis by the empirical orthogonal function (EOF) method confirmed the previous findings that the mean wind speed was decreasing in Shenzhen and that two different seasonal wind speed spatial distribution patterns existed. Such a study could provide references for wind forecasting and risk assessment in the study area.

Effects of Trees on Wind Flow Variability and Turbulence

1990 ◽  
Vol 112 (4) ◽  
pp. 320-325
Author(s):  
D. L. Elliott ◽  
J. C. Barnard
Keyword(s):  
Surface Roughness ◽  
Wind Speed ◽  
Power Output ◽  
Flow Characteristics ◽  
Wind Flow ◽  
Considerable Decrease ◽  
Flow Variability ◽  
Mean Wind Speed ◽  
Variable Power ◽  
The Mean

This paper describes the results of a field experiment at the Goodnoe Hills, Wash. site to examine the effects of trees on wind flow variability and turbulence. Although vegetation at the site consisted primarily of grass, scattered areas of trees that penetrated the site provided an excellent opportunity to evaluate the effects of surface roughness changes on the wind flow characteristics. Wind data collected at nine towers across the site revealed that surface roughness changes in the upwind fetch caused pronounced variations in the wind flow over site. At two towers that were frequently 200 m to 300 m downwind of a grove of 10-m to 18-m trees, 20–30 percent reductions in wind speed and a factor of two to three increase in turbulence were measured at a height of 32 m. A substantial increase in the magnitude of the wind gusts, as well as a considerable decrease in the mean wind speed, was observed when a tower was downwind of the trees. Implications for a wind turbine located downwind of the trees, with a hub height near 30 m, would be reduced power output, more variable power output, more start/stop cycles, and increased stress caused by the tree-induced turbulence. The effects of the trees on the wind flow characteristics were considerably reduced at heights of 60 m and at distances greater than 500 m.

scholarly journals Energy and power estimation for three different locations in Palestine

2019 ◽  
Vol 14 (3) ◽  
pp. 1049 ◽  
Author(s):  
Ahmed S A Badawi ◽  
Nurul Fadzlin Hasbullaha ◽  
Siti Hajar Yusoff ◽  
Aisha Hassan Hashim
Keyword(s):  
Renewable Energy ◽  
Wind Speed ◽  
Wind Energy ◽  
Meteorological Data ◽  
Gaza Strip ◽  
Energy Potential ◽  
Average Wind Speed ◽  
Average Wind ◽  
Mean Wind Speed ◽  
Power And Energy

In this paper power energy estimated based on wind speed records in three different areas in Palestine Nablus, Ramallah and Gaza. The main aims of this study to calculate the total amount of power and energy that can produce and to encourage investment in renewable energy in Palestine. Available meteorological data from local weather stations are used to study the wind energy potential in the West Bank (WB) for two sites and Gaza Strip (GS) for one site. The daily average wind speed data for three sites in Palestine analyzed, and fitted to the Weibull probability distribution function. The parameters of Weibull have been calculated by author using Graphical method. This study shed lights on the relationship between the wind energy and power versus the mean wind speed (MWS). The total gathered energy per unit area during 2006 in WB from Nablus site is 927.1 kwhr/m<sup>2</sup>, whereas 2008.0141 kwhr/m<sup>2</sup> from Ramallah site.This significant study to assess the wind energy production in Palestine to encourage investment in renewable energy sectors.

scholarly journals Aero-elastic Wind Turbine Design with Active Flaps for AEP Maximization

2017 ◽  
Author(s):  
Michael K. McWilliam ◽  
Thanasis K. Barlas ◽  
Helge A. Madsen ◽  
Frederik Zahle
Keyword(s):  
Wind Speed ◽  
Wind Turbine ◽  
Integrated Design ◽  
Blade Design ◽  
Average Wind Speed ◽  
Peak Loads ◽  
Average Wind ◽  
Mean Wind Speed ◽  
Passive Strategies ◽  
Turbine Design

Abstract. In optimal wind turbine design, there is a compromise between maximizing the energy producing forces and minimizing the absolute peak loads carried by the structures. Active flaps are an attractive strategy because they give engineers greater freedom to vary the aerodynamic forces under any condition. Flaps can be used in a variety of different ways (i.e. reducing fatigue, peak loads etc.), however this article focuses on how quasi-static actuation as a function of mean wind speed can be used for Annual Energy Production (AEP) maximization. Numerical design optimization of the DTU 10 MW Reference Wind Turbine (RWT), with the HAWTOpt2 framework, was used to both find the optimal flap control strategy and the optimal turbine designs. The research shows that active flaps can provide a 1 % gain in AEP for aero-structurally optimized blades in both add-on (i.e. the flap is added after the blade is designed) and integrated (i.e. the blade design and flap angle is optimized together) solutions. The results show that flaps are complementary to passive load alleviation because they provide high-order alleviation, where passive strategies only provide linear alleviation with respect to average wind speed. However, the changing loading from the flaps further complicates the design of torsionally active blades, thus, integrated design methods are needed to design these systems.

scholarly journals Characteristics of the Near-Ground Typhoon Morakot

2021 ◽  
Vol 2021 ◽  
pp. 1-12
Author(s):  
Yanru Wang ◽  
Yongguang Li ◽  
Bin Fu ◽  
Xu Wang ◽  
Chuanxiong Zhang ◽  
...  
Keyword(s):  
Wind Speed ◽  
Density Distribution ◽  
Probability Density ◽  
Probability Density Distribution ◽  
Autocorrelation Coefficient ◽  
Typhoon Morakot ◽  
Mean Wind Speed ◽  
The Mean ◽  
Fluctuating Wind ◽  
Good Agreement

Two WJ-3 anemometers placed at the same height on the top of an architectural engineering building in Wenzhou University are used to determine the wind speed of Typhoon Morakot during its landing in real time. This study aims to explore Typhoon Morakot’s wind field characteristics, including mean wind speed, probability density distribution of fluctuating wind speed, power spectral density, correlation analysis, and coherence, on the basis of data measured by the two anemometers. Results show that the probability density distribution of the fluctuating wind speed of the typhoon follows the Gaussian distribution, and the measured cross-power spectrum of fluctuating wind speed is in good agreement with the modified Karman spectrum. The autocorrelation decreases with the increase in time interval (τ). The longitudinal autocorrelation coefficient decays rapidly with the increase in τ, and the lateral autocorrelation coefficient decays at an unchanged rate. The exponential attenuation coefficients of the longitudinal and transverse fluctuating wind speeds increase with the increase in the mean wind speed, and their mean values are 10.86 and 15.33, respectively. The change trends of the coherence coefficients of the two wind speed components with the mean wind speed are the same. The measured coherence coefficients of the two wind speed components are in good agreement with the exponential function.

scholarly journals Aero-elastic wind turbine design with active flaps for AEP maximization

2018 ◽  
Vol 3 (1) ◽  
pp. 231-241 ◽  
Author(s):  
Michael K. McWilliam ◽  
Thanasis K. Barlas ◽  
Helge A. Madsen ◽  
Frederik Zahle
Keyword(s):  
Wind Speed ◽  
Wind Turbine ◽  
Integrated Design ◽  
Blade Design ◽  
Average Wind Speed ◽  
Peak Loads ◽  
Average Wind ◽  
Mean Wind Speed ◽  
Passive Strategies ◽  
Turbine Design

Abstract. In optimal wind turbine design, there is a compromise between maximizing the energy producing forces and minimizing the absolute peak loads carried by the structures. Active flaps are an attractive strategy because they give engineers greater freedom to vary the aerodynamic forces under any condition. Flaps can be used in a variety of different ways (i.e. reducing fatigue, peak loads), but this article focuses on how quasi-static actuation as a function of mean wind speed can be used for annual energy production (AEP) maximization. Numerical design optimization of the DTU 10 MW reference wind turbine (RWT), with the HAWTOpt2 framework, was used to both find the optimal flap control strategy and the optimal turbine designs. The research shows that active flaps can provide a 1 % gain in AEP for aero-structurally optimized blades in both add-on (i.e. the flap is added after the blade is designed) and integrated (i.e. the blade design and flap angle is optimized together) solutions. The results show that flaps are complementary to passive load alleviation because they provide high-order alleviation, where passive strategies only provide linear alleviation with respect to average wind speed. However, the changing loading from the flaps further complicates the design of torsionally active blades; thus, integrated design methods are needed to design these systems.

SHAPING OF AN AUTONOMOUS POWER SYSTEM FOR GUARANTEED POWER SUPPLY WITH THE PREDOMINANCE WIND ENERGY

2018 ◽  
pp. 28-50
Author(s):  
S. G. Ignatiev ◽  
S. V. Kiseleva
Keyword(s):  
Energy Storage ◽  
Wind Speed ◽  
Wind Energy ◽  
Wind Turbine ◽  
Wind Turbines ◽  
Energy Demand ◽  
Diesel Generator ◽  
Average Wind Speed ◽  
Wind Speeds ◽  
Average Wind

Optimization of the autonomous wind-diesel plants composition and of their power for guaranteed energy supply, despite the long history of research, the diversity of approaches and methods, is an urgent problem. In this paper, a detailed analysis of the wind energy characteristics is proposed to shape an autonomous power system for a guaranteed power supply with predominance wind energy. The analysis was carried out on the basis of wind speed measurements in the south of the European part of Russia during 8 months at different heights with a discreteness of 10 minutes. As a result, we have obtained a sequence of average daily wind speeds and the sequences constructed by arbitrary variations in the distribution of average daily wind speeds in this interval. These sequences have been used to calculate energy balances in systems (wind turbines + diesel generator + consumer with constant and limited daily energy demand) and (wind turbines + diesel generator + consumer with constant and limited daily energy demand + energy storage). In order to maximize the use of wind energy, the wind turbine integrally for the period in question is assumed to produce the required amount of energy. For the generality of consideration, we have introduced the relative values of the required energy, relative energy produced by the wind turbine and the diesel generator and relative storage capacity by normalizing them to the swept area of the wind wheel. The paper shows the effect of the average wind speed over the period on the energy characteristics of the system (wind turbine + diesel generator + consumer). It was found that the wind turbine energy produced, wind turbine energy used by the consumer, fuel consumption, and fuel economy depend (close to cubic dependence) upon the specified average wind speed. It was found that, for the same system with a limited amount of required energy and high average wind speed over the period, the wind turbines with lower generator power and smaller wind wheel radius use wind energy more efficiently than the wind turbines with higher generator power and larger wind wheel radius at less average wind speed. For the system (wind turbine + diesel generator + energy storage + consumer) with increasing average speed for a given amount of energy required, which in general is covered by the energy production of wind turbines for the period, the maximum size capacity of the storage device decreases. With decreasing the energy storage capacity, the influence of the random nature of the change in wind speed decreases, and at some values of the relative capacity, it can be neglected.

Prediction of Atmospheric Turbulence Characteristics for Surface Boundary Layer using Empirical Spectral Methods

2020 ◽  
Author(s):  
Yagya Dutta Dwivedi ◽  
Vasishta Bhargava Nukala ◽  
Satya Prasad Maddula ◽  
Kiran Nair
Keyword(s):  
Boundary Layer ◽  
Time Series ◽  
Surface Roughness ◽  
Wind Speed ◽  
Atmospheric Turbulence ◽  
Surface Boundary ◽  
Low Frequencies ◽  
Surface Boundary Layer ◽  
Power Spectral ◽  
Mean Wind Speed

Abstract Atmospheric turbulence is an unsteady phenomenon found in nature and plays significance role in predicting natural events and life prediction of structures. In this work, turbulence in surface boundary layer has been studied through empirical methods. Computer simulation of Von Karman, Kaimal methods were evaluated for different surface roughness and for low (1%), medium (10%) and high (50%) turbulence intensities. Instantaneous values of one minute time series for longitudinal turbulent wind at mean wind speed of 12 m/s using both spectra showed strong correlation in validation trends. Influence of integral length scales on turbulence kinetic energy production at different heights is illustrated. Time series for mean wind speed of 12 m/s with surface roughness value of 0.05 m have shown that variance for longitudinal, lateral and vertical velocity components were different and found to be anisotropic. Wind speed power spectral density from Davenport and Simiu profiles have also been calculated at surface roughness of 0.05 m and compared with k−1 and k−3 slopes for Kolmogorov k−5/3 law in inertial sub-range and k−7 in viscous dissipation range. At high frequencies, logarithmic slope of Kolmogorov −5/3rd law agreed well with Davenport, Harris, Simiu and Solari spectra than at low frequencies.

scholarly journals Analysis of Performance of the Wind-Driven Pulverizing Aerator Based on Average Wind Speeds in the Conditions of Góreckie Lake

Energies ◽  
2021 ◽  
Vol 14 (10) ◽  
pp. 2796
Author(s):  
Andrzej Osuch ◽  
Ewa Osuch ◽  
Stanisław Podsiadłowski ◽  
Piotr Rybacki
Keyword(s):  
Mathematical Model ◽  
Wind Speed ◽  
Water Pump ◽  
Average Wind Speed ◽  
Flow Rates ◽  
Wind Speeds ◽  
Average Wind ◽  
Flow Through ◽  
Analysis Of Performance ◽  
Research Period

In the introduction to this paper, the characteristics of Góreckie lake and the construction and operation of the wind-driven pulverizing aerator are presented. The purpose of this manuscript is to determine the efficiency of the pulverizing aerator unit in the windy conditions of Góreckie Lake. The efficiency of the pulverization aerator depends on the wind conditions at the lake. It was necessary to conduct thorough research to determine the efficiency of water flow through the pulverization segment (water pump). It was necessary to determine the rotational speed of the paddle wheel, which depended on the average wind speed. Throughout the research period, measurements of hourly average wind speed were carried out. It was possible to determine the efficiency of the machine by developing a dedicated mathematical model. The latest method was used in the research, consisting of determining the theoretical volumetric flow rates of water in the pulverizing aerator unit, based on average hourly wind speeds. Pulverization efficiency under the conditions of Góreckie Lake was determined based on 6600 average wind speeds for spring, summer and autumn, 2018. Based on the model, the theoretical efficiency of the machine was calculated, which, under the conditions of Góreckie Lake, amounted to 75,000 m3 per year.

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