scholarly journals Wind speed estimation in urban areas based on the relationships between background wind speeds and morphological parameters

2020 ◽  
Vol 205 ◽  
pp. 104324 ◽  
Author(s):  
Jang-Woon Wang ◽  
Ho-Jin Yang ◽  
Jae-Jin Kim
Keyword(s):  
Wind Speed ◽  
Urban Areas ◽  
Speed Estimation ◽  
Morphological Parameters ◽  
Background Wind ◽  
Wind Speeds

Comparison of Various Blade Profiles in a Two-Blade Conventional Savonius Wind Turbine

2020 ◽  
Vol 143 (2) ◽  
Author(s):  
Rahim Hassanzadeh ◽  
Milad Mohammadnejad ◽  
Sajad Mostafavi
Keyword(s):  
Wind Speed ◽  
Wind Turbine ◽  
Power Output ◽  
Urban Areas ◽  
Cost Effective ◽  
Maximum Power ◽  
Power Coefficient ◽  
Total Power ◽  
Wind Speeds ◽  
Savonius Wind Turbine

Abstract Savonius turbines are one of the old and cost-effective turbines which extract the wind energy by the drag force. Nowadays, they use in urban areas to generate electricity due to their simple structure, ease of maintenance, and acceptable power output under a low wind speed. However, their efficiency is low and the improvement of their performance is necessary to increase the total power output. This paper compares four various blade profiles in a two-blade conventional Savonius wind turbine. The ratios of blade diameter to the blade depth of s/d = 0.3, 0.5, 0.7, and 1 are tested under different free-wind speeds of 3, 5, and 7 m/s and tip speed ratios (TSRs) in the range from 0.2 to 1.2. It is found that the profile of blades in a Savonius rotor plays a considerable role in power characteristics. Also, regardless of blades profile and free-wind speed, the maximum power coefficient develops in TSR = 0.8. In addition, increasing the free-wind speed enhances the rotor performance of all cases under consideration. Finally, it is revealed that the rotor with s/d = 0.5 provides maximum power coefficients in all free-wind speeds and TSR values among the rotors under consideration, whereas the rotor with s/d = 1 is the worth cases.

scholarly journals Towards accurate methane point-source quantification from high-resolution 2-D plume imagery

2019 ◽  
Vol 12 (12) ◽  
pp. 6667-6681 ◽  
Author(s):  
Siraput Jongaramrungruang ◽  
Christian Frankenberg ◽  
Georgios Matheou ◽  
Andrew K. Thorpe ◽  
David R. Thompson ◽  
...  
Keyword(s):  
Wind Speed ◽  
Infrared Imaging ◽  
Methane Flux ◽  
Point Sources ◽  
Emission Rates ◽  
Flux Rate ◽  
Background Wind ◽  
Imaging Spectrometer ◽  
Wind Speeds ◽  
Methane Enhancement

Abstract. Methane is the second most important anthropogenic greenhouse gas in the Earth climate system but emission quantification of localized point sources has been proven challenging, resulting in ambiguous regional budgets and source category distributions. Although recent advancements in airborne remote sensing instruments enable retrievals of methane enhancements at an unprecedented resolution of 1–5 m at regional scales, emission quantification of individual sources can be limited by the lack of knowledge of local wind speed. Here, we developed an algorithm that can estimate flux rates solely from mapped methane plumes, avoiding the need for ancillary information on wind speed. The algorithm was trained on synthetic measurements using large eddy simulations under a range of background wind speeds of 1–10 m s−1 and source emission rates ranging from 10 to 1000 kg h−1. The surrogate measurements mimic plume mapping performed by the next-generation Airborne Visible/Infrared Imaging Spectrometer (AVIRIS-NG) and provide an ensemble of 2-D snapshots of column methane enhancements at 5 m spatial resolution. We make use of the integrated total methane enhancement in each plume, denoted as integrated methane enhancement (IME), and investigate how this IME relates to the actual methane flux rate. Our analysis shows that the IME corresponds to the flux rate nonlinearly and is strongly dependent on the background wind speed over the plume. We demonstrate that the plume width, defined based on the plume angular distribution around its main axis, provides information on the associated background wind speed. This allows us to invert source flux rate based solely on the IME and the plume shape itself. On average, the error estimate based on randomly generated plumes is approximately 30 % for an individual estimate and less than 10 % for an aggregation of 30 plumes. A validation against a natural gas controlled-release experiment agrees to within 32 %, supporting the basis for the applicability of this technique to quantifying point sources over large geographical areas in airborne field campaigns and future space-based observations.

Estimation of Wind Speeds in Urban Areas Using Look-up Tables for Wind-speed Change Rate Simulated by a CFD Model

2020 ◽  
Author(s):  
Jang-Woon Wang ◽  
Jae-Jin Kim ◽  
Ho-Jin Yang
Keyword(s):  
Wind Speed ◽  
Urban Areas ◽  
Urban Morphology ◽  
Average Height ◽  
Target Area ◽  
Cfd Model ◽  
Parameterization Method ◽  
Wind Speeds ◽  
Speed Change ◽  
Morphology Parameters

<p>In this study, we developed a new urban parameterization method of wind speeds. The parameterization method uses building morphology parameters (the volumetric fraction, the plane area fraction, and the average height of buildings) for three different areas. For this, we investigated the relationships between the wind speed change rates by buildings and the urban parameters in three target areas. Each target area includes an automated weather station (AWS) at its center. We conducted the multiple regression analysis to make look-up tables for the relationships between the wind speed change rates and the urban morphology parameters for 32 inflow directions in the target areas. For validation, we simulated the wind speeds at the AWSs using a CFD model coupled to the local data assimilation and prediction system (LDAPS), one of the operational numerical prediction systems of the Korean Meteorological Administration. The results showed that the estimated wind speeds at the AWSs in the three target areas were very similar to those simulated by the LDAPS-CFD coupled model as well as those observed at the AWSs.</p>

scholarly journals Monitoring and Modeling Roof-Level Wind Speed in a Changing City

Atmosphere ◽  
2020 ◽  
Vol 11 (1) ◽  
pp. 87
Author(s):  
Kathrin Baumann-Stanzer ◽  
Sirma Stenzel ◽  
Gabriele Rau ◽  
Martin Piringer ◽  
Felix Feichtinger ◽  
...  
Keyword(s):  
Wind Speed ◽  
Wind Energy ◽  
Wind Turbine ◽  
Urban Areas ◽  
Dispersion Model ◽  
Flow Direction ◽  
Energy Yield ◽  
Wind Speeds ◽  
Small Wind Turbine ◽  
Roof Level

Results of an observational campaign and model study are presented demonstrating how the wind field at roof-level in the urban area of Vienna changed due to the construction of a new building nearby. The investigation was designed with a focus on the wind energy yield of a roof-mounted small wind turbine but the findings are also relevant for air dispersion applications. Wind speed profiles above roof top are simulated with the complex fluid dynamics (CFD) model MISKAM (Mikroskaliges Klima- und Ausbreitungsmodell, microscale climate and dispersion model). The comparison to mast measurements reveals that the model underestimates the wind speeds within the first few meters above the roof, but successfully reproduces wind conditions at 10 m above the roof top (corresponding to about 0.5 times the building height). Scenario simulations with different building configurations at the adjacent property result in an increase or decrease of wind speed above roof top depending on the flow direction at the upper boundary of the urban canopy layer (UCL). The maximum increase or decrease in wind speed caused by the alternations in building structure nearby is found to be in the order of 10%. For the energy yield of a roof-mounted small wind turbine at this site, wind speed changes of this magnitude are negligible due to the generally low prevailing wind speeds of about 3.5 m s−1. Nevertheless, wind speed changes of this order could be significant for wind energy yield in urban areas with higher mean wind speeds. This effect in any case needs to be considered in siting and conducting an urban meteorological monitoring network in order to ensure the homogeneity of observed time-series and may alter the emission and dispersion of pollutants or odor at roof level.

scholarly journals Towards accurate methane point-source quantification from high-resolution 2D plume imagery

2019 ◽  
Author(s):  
Siraput Jongaramrungruang ◽  
Christian Frankenberg ◽  
Georgios Matheou ◽  
Andrew Thorpe ◽  
David R. Thompson ◽  
...  
Keyword(s):  
Wind Speed ◽  
Infrared Imaging ◽  
Geographical Area ◽  
Methane Flux ◽  
Point Sources ◽  
Emission Rates ◽  
Flux Rate ◽  
Background Wind ◽  
Wind Speeds ◽  
Methane Enhancement

Abstract. Methane is the second most important anthropogenic greenhouse gas in the Earth climate system but emission quantification of localized point sources has been proven challenging, resulting in ambiguous regional budgets and source categories distributions. Although recent advancements in airborne remote sensing instruments enable retrievals of methane enhancements at unprecedented resolution of 1–5 m at regional scales, emission quantification of individual sources can be limited by the lack of knowledge of local wind speed. Here, we developed an algorithm that can estimate flux rates solely from mapped methane plumes, avoiding the need for ancillary information on wind speed. The algorithm was trained on synthetic measurements using Large Eddy Simulation under a range of background wind speeds of 1–10 m/s and source emission rates ranging from 10 to 1000 kg/hr. The surrogate measurements mimic plume mapping performed by the next generation Airborne Visible/Infrared Imaging Spectrometer (AVIRIS-NG) and provide an ensemble of 2-D snapshots of column methane enhancements at 5m spatial resolution. We make use of the integrated total methane enhancement in each plume, denoted as Integrated Methane Enhancement (IME), and investigate how this IME relates to the actual methane flux rate. Our analysis shows that the IME corresponds to the flux rate non-linearly and is strongly dependent on the background wind speed over the plume. We demonstrate that the plume width, defined based on the plume angular distribution around its main axis, provides information on the associated background wind speed. This allows us to invert source flux rate based solely on the IME and the plume-shape itself. On average, the error estimate based on randomly generated plumes is approximately 30 % for an individual estimates and less than 10 % for an aggregation of 30 plumes. A validation against a natural gas controlled release experiment agree to within 32 %, supporting the basis for the applicability of this technique to quantifying point sources over large geographical area in airborne field campaigns and future space-based observations.

scholarly journals Synergistic Influence of Local Climate Zones and Wind Speeds on the Urban Heat Island and Heat Waves in the Megacity of Beijing, China

2021 ◽  
Vol 9 ◽  
Author(s):  
Lian Zong ◽  
Shuhong Liu ◽  
Yuanjian Yang ◽  
Guoyu Ren ◽  
Miao Yu ◽  
...  
Keyword(s):  
Heat Flux ◽  
Wind Speed ◽  
Urban Heat Island ◽  
Rural Areas ◽  
Urban Areas ◽  
Thermal Environment ◽  
Heat Island ◽  
Wind Speeds ◽  
High Rise ◽  
Urban Heat

Large-scale modifications to urban underlying surfaces owing to rapid urbanization have led to stronger urban heat island (UHI) effects and more frequent urban heat wave (HW) events. Based on observations of automatic weather stations in Beijing during the summers of 2014–2020, we studied the interaction between HW events and the UHI effect. Results showed that the UHI intensity (UHII) was significantly aggravated (by 0.55°C) during HW periods compared to non-heat wave (NHW) periods. Considering the strong impact of unfavorable weather conditions and altered land use on the urban thermal environment, we evaluated the modulation of HW events and the UHI effect by wind speed and local climatic zones (LCZs). Wind speeds in urban areas were weakened due to the obstruction of dense high-rise buildings, which favored the occurrence of HW events. In detail, 35 HW events occurred over the LCZ1 of a dense high-rise building area under low wind speed conditions, which was much higher than that in other LCZ types and under high wind speed conditions (< 30 HW events). The latent heat flux in rural areas has increased more due to the presence of sufficient water availability and more vegetation, while the increase in heat flux in urban areas is mainly in the form of sensible heat flux, resulting in stronger UHI effect during HW periods. Compared to NHW periods, lower boundary layer and wind speed in the HW events weakened the convective mixing of air, further expanding the temperature gap between urban and rural areas. Note that LCZP type with its high-density vegetation and water bodies in the urban park area generally exhibited, was found to have a mitigating effect on the UHI, whilst at the same time increasing the frequency and duration of HW events during HW periods. Synergies between HWs and the UHI amplify both the spatial and temporal coverage of high-temperature events, which in turn exposes urban residents to additional heat stress and seriously threatens their health. The findings have important implications for HWs and UHII forecasts, as well as for scientific guidance on decision-making to improve the thermal environment and to adjust the energy structure.

scholarly journals Micro-scale modelling of the urban wind speed for air pollution applications

2019 ◽  
Vol 9 (1) ◽  
Author(s):  
Thor-Bjørn Ottosen ◽  
Matthias Ketzel ◽  
Henrik Skov ◽  
Ole Hertel ◽  
Jørgen Brandt ◽  
...  
Keyword(s):  
Air Pollution ◽  
Wind Speed ◽  
Urban Areas ◽  
Global Radiation ◽  
Atmospheric Stability ◽  
Sea Breeze ◽  
Building Design ◽  
Obukhov Length ◽  
Wind Speeds ◽  
Scale Modelling

Abstract Modelling wind speeds in urban areas have many applications e.g. in relation to assessment of wind energy, modelling air pollution, and building design and engineering. Models for extrapolating the urban wind speed exist, but little attention has been paid to the influence of the upwind terrain and the foundations for the extrapolation schemes. To analyse the influence of the upwind terrain and the foundations for the extrapolation of the urban wind speed, measurements from six urban and non-urban stations were explored, and a model for the urban wind speed with and without upwind influence was developed and validated. The agreement between the wind directions at the stations is found to be good, and the influence of atmospheric stability, horizontal temperature gradients, land-sea breeze, temperature, global radiation and Monin-Obukhov Length is found to be small, although future work should explore if this is valid for other urban areas. Moreover, the model is found to perform reasonably well, but the upwind influence is overestimated. Areas of model improvement are thus identified. The upwind terrain thus influences the modelling of the urban wind speed to a large extent, and the fundamental assumptions for the extrapolation scheme are fulfilled for this specific case.

An Assessment on the Wind Energy Potential and Possible Solutions for Power Generation in Baltimore County in Maryland, USA

2014 ◽  
Author(s):  
N. Goudarzi ◽  
W. D. Zhu ◽  
R. Delgado ◽  
A. St. Pé
Keyword(s):  
Power Generation ◽  
Wind Speed ◽  
Wind Energy ◽  
Urban Areas ◽  
Large Scale ◽  
Energy Resource ◽  
Mean Value ◽  
Baltimore County ◽  
Wind Speeds ◽  
Wind Potential

The statistical data of five years wind speed measurements at University of Maryland, Baltimore County are used to find out the availability of wind energy resource for power generation. Wind speeds are measured at an approximately 30 meters above the ground; the monthly and yearly mean wind speeds are calculated and evaluated by using the Weibull distribution function. The annual values of k (dimensionless Weibull shape parameter) ranged from 1.78 to 1.99 with a five-year mean value of 1.87. The annual values of c (Weibull scale parameter) ranged from 3.15 to 3.60 with a five-year mean value of 3.28. The results show the highest and lowest wind power potential occurs in February and July, respectively. While this site is not appropriate for large-scale power generation, this study shows the availability of enough wind potential for non-grid connected electrical and mechanical applications. Different residential wind harvesting technologies in urban areas have been studied and more promising ones are introduced as solutions to provide larger-scale power generation at this site with a low annual mean wind speed.

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.

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