Wind Speed Profile and Gradient Height in Typhoons Observed by Vehicular Doppler Radar in South China

2010 ◽  
Vol 163-167 ◽  
pp. 3887-3892
Author(s):  
Li Xiao Li ◽  
Yi Qing Xiao ◽  
Li Li Song ◽  
Peng Qin
Keyword(s):  
Wind Speed ◽  
Doppler Radar ◽  
Probability Method ◽  
Wall Region ◽  
Wind Speed Profile ◽  
Wind Speeds ◽  
Mean Wind Speed ◽  
The Mean ◽  
The Times ◽  
Wind Profiles

The recent development of Doppler radar sensor has allowed to study the typhoon wind structure more accuracy and systematic. In order to obtain more wind data near typhoon eye-wall, vehicular Doppler radar emerge as the times require. Based on two typhoon observed results carried out by vehicular Doppler radar in category A terrain, firstly the 10min mean wind profiles under 1000m height in different regions of typhoon were analyzed. The typhoon mean wind speeds increase a logarithmic law with height at nearly lower two hundred meters in all regions of typhoons. Using the power law to fit wind profiles, the exponential index α in pre-eye-wall region is greater than it in post-eye-wall region, and it decreases with increasing the mean wind speed. Secondly, based on analyzing the relationship between mean wind speed and wind ratio, the calculation formula for nominal gradient height were established in category A terrain. Finally introducing the probability method to study the mean wind profile, the exponential index α was established in category A terrain.

scholarly journals Validation of Dual-Doppler Wind Profiles with in situ Anemometry

2015 ◽  
Vol 32 (5) ◽  
pp. 943-960 ◽  
Author(s):  
W. Scott Gunter ◽  
John L. Schroeder ◽  
Brian D. Hirth
Keyword(s):  
High Resolution ◽  
Wind Speed ◽  
Doppler Radar ◽  
Heavy Precipitation ◽  
Atmospheric Conditions ◽  
Wind Speeds ◽  
Time Histories ◽  
Mean Wind Speed ◽  
Wind Profiles

AbstractTypical methods used to acquire wind profiles from Doppler radar measurements rely on plan position indicator (PPI) scans being performed at multiple elevation angles to utilize the velocity–azimuth display technique or to construct dual-Doppler synthesis. These techniques, as well as those employed by wind profilers, often produce wind profiles that lack the spatial or temporal resolution to resolve finescale features. If two radars perform range–height indicator (RHI) scans (constant azimuth, multiple elevations) along azimuths separated by approximately 90°, then the intersection of the coordinated RHI planes represents a vertical set of points where dual-Doppler wind syntheses are possible and wind speed and direction profiles can be retrieved. This method also allows for the generation of high-resolution wind time histories that can be compared to anemometer time histories. This study focuses on the use of the coordinated RHI scanning strategy by two high-resolution mobile Doppler radars in close proximity to a 200-m instrumented tower. In one of the first high-resolution, long-duration comparisons of dual-Doppler wind synthesis with in situ anemometry, the mean and turbulence states of the wind measured by each platform were compared in varying atmospheric conditions. Examination of mean wind speed and direction profiles in both clear-air (nonprecipitating) and precipitating environments revealed excellent agreement above approximately 50 m. Below this level, dual-Doppler wind speeds were still good but slightly overestimated as compared to the anemometer-measured wind speeds in heavy precipitation. Bulk turbulence parameters were also slightly underestimated by the dual-Doppler syntheses.

Wind tunnel tests on the characteristics of wind fields over a simplified gorge

2016 ◽  
Vol 20 (10) ◽  
pp. 1599-1611 ◽  
Author(s):  
Peng Hu ◽  
Yongle Li ◽  
Yan Han ◽  
CS Cai ◽  
Guoji Xu
Keyword(s):  
Wind Speed ◽  
Wind Tunnel ◽  
Wind Direction ◽  
Wind Field ◽  
Small Range ◽  
Wind Fields ◽  
Wind Speeds ◽  
Mean Wind Speed ◽  
Wind Characteristics ◽  
The Mean

Characteristics of wind fields over the gorge or valley terrains are becoming more and more important to the structural wind engineering. However, the studies on this topic are very limited. To obtain the fundamental characteristics information about the wind fields over a typical gorge terrain, a V-shaped simplified gorge, which was abstracted from some real deep-cutting gorges where long-span bridges usually straddle, was introduced in the present wind tunnel studies. Then, the wind characteristics including the mean wind speed, turbulence intensity, integral length scale, and the wind power spectrum over the simplified gorge were studied in a simulated atmospheric boundary layer. Furthermore, the effects of the oncoming wind field type and oncoming wind direction on these wind characteristics were also investigated. The results show that compared with the oncoming wind, the wind speeds at the gorge center become larger, but the turbulence intensities and the longitudinal integral length scales become smaller. Generally, the wind fields over the gorge terrain can be approximately divided into two layers, that is, the gorge inner layer and the gorge outer layer. The different oncoming wind field types have remarkable effects on the mean wind speed ratios near the ground. When the angle between the oncoming wind and the axis of the gorge is in a certain small range, such as smaller than 10°, the wind fields are very close to those associated with the wind direction of 0°. However, when the angle is in a larger range, such as larger than 20°, the wind fields in the gorge will significantly change. The research conclusions can provide some references for civil engineering practices regarding the characteristics of wind fields over the real gorge terrains.

scholarly journals Spreadsheet solution for the computation of the mean wind speed and turbulence intensity profiles according to the Romanian standard

2019 ◽  
Vol 85 ◽  
pp. 03002
Author(s):  
Elena-Alexandra Chiulan ◽  
Andrei-Mugur Georgescu ◽  
Costin-Ioan Coşoiu ◽  
Anton Anton
Keyword(s):  
Wind Speed ◽  
Turbulence Intensity ◽  
Structural Design ◽  
Input Data ◽  
Wind Speed Profile ◽  
Wind Action ◽  
Design Engineers ◽  
Mean Wind Speed ◽  
Wind Characteristics ◽  
The Mean

The presented paper focuses on the computation of the mean wind speed and turbulence intensity profiles for all the cities from Romania. The calculation of both, the mean wind speed profile and the turbulence intensity profile, had as mathematical support the equations presented in the Romanian design standard for wind action CR 1-1-4/2012. The main objective of this paper was to provide a tool for the computation of the two wind action features. This method was based on creating a spreadsheet in Excel with which, in just a few seconds, a user could correctly obtain the two wind characteristics. This Excel dashboard can be used as a teaching material for students as well as input data for structural design engineers in the process of modelling and observing the behaviour of a building excited by wind action on a particular city in Romania.

ANALYSIS OF PEDESTRIAN-LEVEL WIND VELOCITY IN FOUR NEIGHBOURHOODS IN KLANG VALLEY

2015 ◽  
Vol 76 (5) ◽  
Author(s):  
Azli Abd Razak ◽  
Mohd Azhari Mohd Rodzi ◽  
Amirul Hakim Jumali ◽  
Sheikh Ahmad Zaki
Keyword(s):  
Wind Speed ◽  
Field Measurements ◽  
Area Ratio ◽  
Frontal Area ◽  
Speed Ratio ◽  
Pollution Dispersion ◽  
Wind Speeds ◽  
Mean Wind Speed ◽  
Klang Valley ◽  
The Mean

Urban ventilation is important for the purpose of pollution dispersion, indoor ventilation for free running buildings and urban thermal comfort. In comparison to suburban cities, high-density cities have very low wind speeds at pedestrian level due to the densely built buildings blocking the wind and creating stagnant zones locally. Under this circumstance, field measurements were performed to investigate the performance of pedestrian wind at four major cities in Klang Valley. Mean wind speed was measured using anemometers at 1 minute data interval for 3 hours  and the  data collection for each case were obtained at pedestrian level. The mean wind speed ratio was plotted against the frontal area ratio and plan area ratio. The result indicates that: (1) the mean wind speed dramatically decreases with the increase of plan area ratio and (2) the mean wind speed exponentially decreases with the increase of frontal area ratio and qualitatively agrees with the power law relationship which is proposed by previous researcher. In addition, the frontal area ratio is considered as a better parameter to evaluate the performance of urban ventilation. 

scholarly journals Wind speed analysis based on the logarithmic wind shear model: a case study for some brazilian cities

2020 ◽  
Vol 9 (7) ◽  
pp. e298973984
Author(s):  
Anny Key de Souza Mendonça ◽  
Antonio Cezar Bornia
Keyword(s):  
Wind Speed ◽  
Wind Power ◽  
Wind Shear ◽  
Wind Farms ◽  
Shear Model ◽  
The Public ◽  
Wind Speeds ◽  
Generating Capacity ◽  
Mean Wind Speed ◽  
The Mean

The wind power’ share in electricity generating capacity has increased significantly in recent years. Due to the variability in wind power generation, given the variations in wind speed and considering the increase in wind participation in the Brazilian energy matrix, a fact that reinforces the relevance of the source, this article aims to present the methods used to analyze the wind speed more used in the literature and to analyze the wind speed in several Brazilian cities. The logarithmic wind shear model was used to analyze mean wind speeds based on historical data of twelve Brazilian cities available to the public on the ESRL database for a period of eight years 2010 to 2018. The study showed that in localities such as Uruguaiana/RS, Campo Grande/MS, Uberlândia/MG, São Luiz/MA and Corumba/MS, mean wind speeds are strong in all altitudes of reference, with a gain of ± 2m/s of wind speed as the operational altitude increases. The logarithmic wind gain in high altitudes or low altitudes can be seen in z = 100 meters, where the mean wind speed found was Wn ≈ 8 m/s in Uruguaiana/RS and Campo Grande/MS, whereas in Manaus it was Wn ≈ 5 m/s. In Porto Alegre (RS), Florianópolis (SC), Curitiba/PR and Brasília/DF, the mean wind speed in altitudes ≥ 250 m becomes significant, allowing the implementation of wind farms if the technology proves to be economically feasible.

scholarly journals Statistical Analysis of Wind Speed & Wind Direction in Tantan Province, Morocco

2019 ◽  
Vol 8 (4) ◽  
pp. 3955-3959
Keyword(s):  
Wind Speed ◽  
Wind Power ◽  
Wind Direction ◽  
Energy System ◽  
Average Frequency ◽  
Wind Rose ◽  
Data Set ◽  
Wind Speeds ◽  
Mean Wind Speed ◽  
The Mean

In this paper, a two-parameter Weibull statistical distribution is used to analyze the characteristics of the wind from the Saharan area, located in the Tantan province, Morocco, for 08 years at 10 m. During those 08 years (2009-2017) the frequency distribution of the wind speed, the wind direction, the mean wind speed, the shape and scale (k & c) Weibull parameters have been calculated for the province. The mean wind speed for the entire data set is 6.4 m/s. The parameters k & c are found as 1.9 and 2.52 m/s in relative order. The study also provides an analysis of the wind direction along with a wind rose chart for the province. The analysis suggests that the highest wind speeds that vary (vm = 5.1m/s; vmax = 18.5m/s) prevail between sectors 165-175 ° with an average frequency of 1.4% and lower wind speeds (vm = 2.5m/s; vmax = 9.7m/s) occur between sectors 245-255° with an average frequency of 0.6%. The results of this document help to understand the wind power potential of the province and serve as a source of wind power projects. From a perspective, the wind energy system is an alternative to the future of the Sahara province of Morocco.

scholarly journals The Response of the Dines Anemometer to Gusts and Comparisons with Cup Anemometers

2013 ◽  
Vol 30 (7) ◽  
pp. 1320-1336 ◽  
Author(s):  
Craig Miller ◽  
John Holmes ◽  
David Henderson ◽  
John Ginger ◽  
Murray Morrison
Keyword(s):  
Wind Speed ◽  
High Speed ◽  
Moving Average ◽  
Extreme Value Analysis ◽  
Recording Instrument ◽  
Amplitude Response ◽  
Value Analysis ◽  
Wind Speeds ◽  
Mean Wind Speed ◽  
The Mean

Abstract The Dines pressure tube anemometer was the primary wind speed recording instrument used in Australia until it was replaced by Synchrotac cup anemometers in the 1990s. Simultaneous observations of the gust wind speeds recorded using both types of anemometers during tropical cyclones have, however, raised questions about the equivalency of the gust wind speeds recorded using the two instruments. An experimental study of the response of both versions of the Dines anemometer used in Australia shows that the response of the anemometer is dominated by the motion of the float manometer used to record the wind speed. The amplitude response function shows the presence of two resonant peaks, with the amplitude and frequency of the peaks depending on the instrument version and the mean wind speed. Comparison of the gust wind speeds recorded using Dines and Synchrotac anemometers using random process and linear system theory shows that, on average, the low-speed Dines anemometer records values 2%–5% higher than those recorded using a Synchrotac anemometer under the same conditions, while the high-speed Dines anemometer records values 3%–7% higher, depending on the mean wind speed and turbulence intensity. These differences are exacerbated with the adoption of the WMO-recommended 3-s moving average gust wind speed when reporting the Synchrotac anemometer gust wind speeds, rising to 6%–12% and 11%–19% for low- and high-speed Dines anemometers, respectively. These results are consistent with both field observations and an independent extreme value analysis of simultaneously observed gust wind speeds at seven sites in northern Australia.

scholarly journals Atmospheric boundary layer wind profile at a flat coastal site – wind speed lidar measurements and mesoscale modeling results

2011 ◽  
Vol 6 (1) ◽  
pp. 155-159 ◽  
Author(s):  
R. Floors ◽  
E. Batchvarova ◽  
S.-E. Gryning ◽  
A. N. Hahmann ◽  
A. Peña ◽  
...  
Keyword(s):  
Wind Speed ◽  
Wind Profile ◽  
Mesoscale Model ◽  
Stable Conditions ◽  
Lidar Measurements ◽  
Mean Wind Speed ◽  
Wind Lidar ◽  
The Mean ◽  
Wind Profiles ◽  
The Individual

Abstract. Wind profiles up to 600 m height are investigated. Measurements of mean wind speed profiles were obtained from a novel wind lidar and compared to model simulations from a mesoscale model (WRF-ARW v3.1). It is found that WRF is able to predict the mean wind profile rather well and typically within 1–2 m s−1 to the individual measured values. WRF underpredicts the normalized wind profile, especially for stable conditions. The effect of baroclinicity on the upper part of the wind profile is discussed.

Scale and Lag Effects on Control of Aerodynamic Power and Loads on a HAWT Rotor

2001 ◽  
Vol 123 (4) ◽  
pp. 339-345 ◽  
Author(s):  
P. J. Moriarty ◽  
A. J. Eggers, ◽  
K. Chaney ◽  
W. E. Holley
Keyword(s):  
Control System ◽  
Fatigue Life ◽  
Wind Speed ◽  
Open Loop ◽  
Time Lags ◽  
Large Power ◽  
Lag Effects ◽  
Mean Wind Speed ◽  
The Mean ◽  
High Control

The effects of rotor scale and control system lag were examined for a variable-speed wind turbine. The scale study was performed on a teetered rotor with radii ranging between 22.5m and 33.75m. A 50% increase in radius more than doubled the rated power and annual energy capture. Using blade pitch to actively control fluctuating flatwise moments allowed for significant reductions in blade mass for a fixed fatigue life. A blade operated in closed-loop mode with a 33.75m radius weighed less than an open-loop blade with a 22.5m radius while maintaining the same fatigue life of 5×109 rotations. Actuator lag reduced the effectiveness of the control system. However, 50% reductions in blade mass were possible even when implementing a relatively slow actuator with a 1 sec. time constant. Other practical limits on blade mass may include fatigue from start/stop cycles, non-uniform turbulence, tower wake effects, and wind shear. The more aggressive control systems were found to have high control accelerations near 60 deg/s2, which may be excessive for realistic actuators. Two time lags were introduced into the control system when mean wind speed was estimated in a rapidly changing wind environment. The first lag was the length of time needed to determine mean wind speed, and therefore the mean control settings. The second was the frequency at which these mean control settings were changed. Preliminary results indicate that quickly changing the mean settings (every 10 seconds) and using a moderate length mean averaging time (60 seconds) resulted in the longest fatigue life. It was discovered that large power fluctuations occurred during open-loop operation which could cause sizeable damage to a realistic turbine generator. These fluctuations are reduced by one half or more when aerodynamic loads are actively controlled.

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