• Wind and Structures
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• v.24 no.1
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• pp.1-24
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• 2017

Wind environment in urban residential areas is an important index to consider when evaluating the living environment. However, due to the complexity of the flow field in residential areas, it is difficult to specify the correct inflow boundary conditions in the large eddy simulation (LES). In this paper, the weighted amplitude wave superposition (WAWS) is adopted to simulate the fluctuating velocity data, which satisfies the desired target wind field. The fluctuating velocity data are given to the inlet boundary of the LES by developing an UDF script, which is implemented into the FLUENT. Then, two numerical models - the empty numerical wind tunnel model and the numerical wind tunnel model with spires and roughness elements are established based on the wind tunnel experiment to verify the present method. Finally, the turbulence generation approach presented in this paper is used to carry out a numerical simulation on the wind environment in an urban residential area in Lisbon. The computational results are compared with the wind tunnel experimental data, showing that the numerical results in the LES have a good agreement with the experimental results, and the simulated flow field with the inlet fluctuations can generate a reasonable turbulent wind field. It also shows that strong wind velocities and turbulent kinetic energy occur at the passageways, which may affect the comfort of people in the residential neighborhood, and the small wind velocities and vortexes appear at the leeward corners of buildings, which may affect the spreading of the pollutants.

• 한국태양에너지학회:학술대회논문집
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• 2011.04a
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• pp.213-216
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• 2011

The feasibility study must be conducted for construction of complex for generation of electric power such as items to get permission and grid connection etc. including wind resource to construct a complex for wind power generation. Since wind power can be used by converting only around 20~40% of energy coming in that kinetic energy of wind passes through blades and driving device into electric energy, when constructing a complex, the survey of wind resource takes up the most important part. Data logger used to measure this wind energy are expressed by calculating generally electromotive that is created from a sensor, variable-type, pulse-type signal to be proper for the actual value, and most data loggers have a type without considering geographical features. Besides, in the case of Met mast that is installed to survey the wind resource, since it is installed lower than the hub height of a wind power generator due to permission matters and the economic factors, the height of wind speed by utilizing Deacon equation is compensated to revise this. In this study, a device measuring wind speed was made by using algorithm that is possible to compensate the height of wind speed according to regional features and by applying Deacon equation, and the function of data storage through SD card or RS232 communication was added as well. Besides it's possible to check data more easily with a type of graph by using LCD touch screen for the convenience of users.

• Journal of Ocean Engineering and Technology
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• v.36 no.6
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• pp.380-389
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• 2022

In the Haeundae area of Busan, South Korea, damage has continued to occur recently from building wind from caused by dense skyscrapers. Five wind observation stations were installed near LCT residential towers in Haeundae to analyze the effect of building winds during typhoon Omais. The impact of building wind was analyzed through relative and absolute evaluations. At an intersection located southeast of LCT (L-2), the strongest wind speed was measured during the monitoring. The maximum average wind speed for one minute was observed to be 38.93 m/s, which is about three times stronger than at an ocean observation buoy (12.7 m/s) at the same time. It is expected that 3 to 4 times stronger wind can be induced under certain conditions compared to the surrounding areas due to the building wind effect. In a Beaufort wind scale analysis, the wind speed at an ocean observatory was mostly distributed at Beaufort number 4, and the maximum was 8. At L-2, more than 50% of the wind speed exceeded Beaufort number 4, and numbers up to 12 were observed. However, since actual measurement has a limitation in analyzing the entire range, cross-validation with computational fluid dynamics simulation data is required to understand the characteristics of building winds.

• Structural Engineering and Mechanics
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• v.48 no.4
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• pp.435-453
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• 2013

A new computational approach for the rain load on the transmission tower is presented to obtain the responses of system subjected to the wind and rain combined excitations. First of all, according to the similarity theory, the aeroelastic modeling of high-voltage transmission tower is introduced and two kinds of typical aeroelastic models of transmission towers are manufactured for the wind tunnel tests, which are the antelope horn tower and pole tower. And then, a formula for the pressure time history of rain loads on the tower structure is put forward. The dynamic response analyses and experiments for the two kinds of models are carried out under the wind-induced and wind-rain-induced actions with the uniform and turbulent flow. It has been shown that the results of wind-rain-induced responses are bigger than those of only wind-induced responses and the rain load influence on the transmission tower can't be neglected during the strong rainstorm. The results calculated by the proposed method have a good agreement with those by the wind tunnel test. In addition, the wind-rain-induced responses along and across the wind direction are in the same order of response magnitude of towers.

• Wind and Structures
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• v.30 no.3
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• pp.261-273
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• 2020

This paper deals with the design, wind tunnel testing, and performance analysis of small wind turbines targeting low-power applications. Three different small-size blade designs in terms of size, shape, and twisting angle are considered and tested. We conduct wind tunnel tests while measuring the angular speed of the rotating blades, the generated voltage, and the current under varying resistive loading and air flow conditions. An electromechanical model is also used to predict the measured voltage and power and verify their consistency and repeatability. The measurements are found in qualitative agreement with those reported in previously-published experimental works. We present a novel methodology to estimate the mechanical torque applied to the wind turbine without the deployment of a torque measuring device. This method can be used to determine the power coefficient at a given air speed, which constitutes an important performance indicator of wind turbines. The wind tunnel tests revealed the capability of the developed wind turbines to deliver more than 1225 mW when subject to an air flow with a speed of 7 m/s. The power coefficient is found ranging between 26% and 32%. This demonstrates the aerodynamic capability of the designed blades to extract power from the wind.

• Journal of the Korean Society for Advanced Composite Structures
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• v.5 no.3
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• pp.37-42
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• 2014

Wind turbine tower has a very important role in wind turbine system as one of the renewable energy that has been attracting attention worldwide recently. Due to the growth of wind power market, advance and development of offshore wind system and getting huger capacity is inevitable. As a result, the vibration is generated at wind turbine tower by receiving constantly dynamic loads such as wind load and wave load. Among these dynamic loads, the mechanical load caused by the rotation of the blade is able to make relatively periodic load to the wind turbine tower. So natural frequency of the wind turbine tower should be designed to avoid the rotation frequency of the rotor according to the design criteria to avoid resonance. Currently research of the wind turbine tower, the precise research does not be carried out because of simplifying the structure of the other upper and lower. In this study, the effect of blade modeling differences are to be analyzed in natural frequency of wind turbine tower.

• Wind and Structures
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• v.21 no.2
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• pp.119-158
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• 2015

The characteristics of the coherence functions of X axial, Y axial, and RZ axial (i.e., body axis) wind forces on the Shanghai World Trade Centre - a 492 m super-tall building with section varying along height are studied via a synchronous multi-pressure measurement of the rigid model in wind tunnel simulating of the turbulent, and the corresponding mathematical expressions are proposed there from. The investigations show that the mathematical expressions of coherence functions in across-wind and torsional-wind directions can be constructed by superimposition of a modified exponential decay function and a peak function caused by turbulent flow and vortex shedding respectively, while that in along-wind direction need only be constructed by the former, similar to that of wind speed. Moreover, an inductive analysis method is proposed to summarize the fitted parameters of the wind force coherence functions of every two measurement levels of altitudes. The comparisons of the first three order generalized force spectra show that the proposed mathematical expressions accord with the experimental results well. Later, the influences of coherence functions on wind-induced dynamic responses are analyzed in detail based on the proposed mathematical expressions and the frequency-domain method of random vibration theory.

• Wind and Structures
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• v.22 no.1
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• pp.43-63
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• 2016

In conventional buffeting theory, it is assumed that the aerostatic coefficients along a bridge deck follow the strip assumption. The validity of this assumption is suspect for a cable-stayed bridge in the construction stages, due to the effect of significant aerodynamic interference from the pylon. This situation may be aggravated in skew winds. Therefore, the most adverse buffeting usually occurs when the wind is not normal to bridge axis, which indicates the invalidity of the traditional "cosine rule". In order to refine the studies of static wind load on the deck of cable-stayed bridge under skew wind during its most adverse construction stage, a full bridge 'aero-stiff' model technique was used to identify the aerostatic loads on each deck segment, in smooth oncoming flow, with various yaw angles. The results show that the shelter effect of the pylon may not be ignored, and can amplify the aerostatic loading on the bridge deck under skew winds ($10^{\circ}-30^{\circ}$) with certain wind attack angles, and consequently results in the "cosine rule" becoming invalid for the buffeting estimation of cable-stayed bridge during erection for these wind directions.

• Wind and Structures
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• v.22 no.6
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• pp.703-721
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• 2016

This paper presents a wind tunnel study of wind loads of the large billboard structures with two-plate and three-plate configurations. Synchronous dynamic pressures on the surfaces of plates are measured, and the characteristics of local pressures, integrated forces on each individual plate and on the overall structures are investigated. The influences of wind direction and plate configuration on wind load characteristics, and the contributions of overall crosswind load and torque to the stress responses are examined. The results showed that the wind load characteristics of windward plate in both two- and three-plate configurations are very similar. The contribution of overall crosswind load makes the total resultant force from both alongwind and crosswind loads less sensitive to wind direction in the case of three-plate configuration. The overall torque is lower than the value specified in current codes and standards, and its contribution is less significant in both two-plate and three-plate configurations.

• 한국태양에너지학회:학술대회논문집
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• 2009.11a
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• pp.400-403
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• 2009

Current wind turbine units that are used primarily 3Blade type devices or large-scale wind-term capacity of 2MW of 60m~90m Blade diameter is applied. This is not the best suitable design with the designing condition for the special quality of wind condition in the South-West Coastal Areas of Korea where the wind speed frequency of average wind speed and over 10m/s high wind velocity is fairly low. For this matter, in this dissertation, the expecting generation amount of electric power is measured excluding a mechanical moment, considering wind power energy traveling to the Blade when 60m~120m blade is applied, based on 2MW wind generator. Also, we would like to propose the Blade diameter which is fitted by wind condition of South-West Coastal Areas of Korea.