• Wind and Structures
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• v.9 no.5
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• pp.369-386
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• 2006

A combination Aerodynamic/Atmospheric Boundary Layer (AABL) Wind and Gust Tunnel with a unique active gust generation capability has been developed for wind engineering and industrial aerodynamics applications. This facility is a cornerstone component of the Wind Simulation and Testing (WiST) Laboratory of the Department of Aerospace Engineering at Iowa State University (ISU). The AABL Wind and Gust tunnel is primarily a closed-circuit tunnel that can be also operated in open-return mode. It is designed to accommodate two test sections ($2.44m{\times}1.83m$ and $2.44m{\times}2.21m$) with a maximum wind speed capability of 53 m/s. The gust generator is capable of producing non-stationary gust magnitudes around 27% of the mean flow speed. This paper describes the motivation for developing this gust generator and the work related to its design and testing.

• Wind and Structures
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• v.39 no.4
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• pp.271-285
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• 2024

The multiple-fan wind tunnel is an important facility for reproducing target wind field. Existing control methods for the multiple-fan wind tunnel can generate wind speeds that satisfy the target statistical characteristics of a wind field (e.g., power spectrum). However, the frequency-domain features cannot well represent the nonstationary winds of extreme storms (e.g., downburst). Therefore, this study proposes a multiple-fan wind tunnel control scheme based on Deep Reinforcement Learning (DRL), which will completely transform into a data-driven closed-loop control problem, to reproduce the target wind field in the time domain. Specifically, the control scheme adopts the Deep Deterministic Policy Gradient (DDPG) paradigm in which the strong fitting ability of Deep Neural Networks (DNN) is utilized. It can establish the complex relationship between the target wind speed time series and the current control strategy in the DRL-agent. To address the fluid memory effect of the wind field, this study innovatively designs the system state and control reward to improve the reproduction performance based on historical data. To validate the performance of the model, we established a simplified flow field based on Navier Stokes equations to simulate a two-dimensional numerical multiple-fan wind tunnel environment. Using the strategy of DRL decision maker, we generated a wind speed time series with minor error from the target under low Reynolds number conditions. This is the first time that the AI methods have been used to generate target wind speed time series in a multiple-fan wind tunnel environment. The hyperparameters in the DDPG paradigm are analyzed to identify a set of optimal parameters. With these efforts, the trained DRL-agent can simultaneously reproduce the wind speed time series in multiple positions.

• Wind and Structures
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• v.14 no.1
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• pp.55-70
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• 2011

This study investigates the design criteria required for wind barriers to protect vehicles running on an expressway under a high side wind. At the first stage of this study, the lateral deviations of vehicles in crosswinds were computed from the commercial software, CarSim and TruckSim, and the critical wind speeds for a car accident were then evaluated from a predefined car accident index. The critical wind speeds for driving stability were found to be 35 m/s for a small passenger car, yet 30 m/s for a truck and a bus. From the wind tunnel tests, the minimum height of a wind barrier required to reduce the wind speed by 50% was found to be 12.5% of the road width. In the case of parallel bridges, the placement of two edge wind barriers plus one wind barrier at center was recommended for a separation distance larger than 20 m (four lanes) and 10 m (six lanes) respectively, otherwise two wind barriers were recommended.

• Wind and Structures
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• v.13 no.5
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• pp.433-449
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• 2010

Wind tunnel model tests were conducted for a residential apartment block located within the complex terrain of The Hong Kong University of Science and Technology (HKUST). The test building is typical of medium-rise residential buildings in Hong Kong. The model study was conducted using modelling techniques and assumptions that are commonly used to predict design wind loads and pressures for buildings sited in regions of significant topography. Results for the building model with and without the surrounding topography were compared to investigate the effects of far-field and near-field topography on wind characteristics at the test building site and wind-induced external pressure coefficients at key locations on the building facade. The study also compared the wind tunnel test results to topographic multipliers and external pressure coefficients determined from nine international design standards. Differences between the external pressure coefficients stipulated in the various standards will be exacerbated when they are combined with the respective topographic multipliers.

• Wind and Structures
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• v.4 no.4
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• pp.299-314
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• 2001

A study of wind effects was carried out at the Boundary Layer Wind Tunnel Laboratory (BLWTL) for the projected 558-m high free-standing telecommunication and observation tower for Jakarta, Indonesia. The objectives were to assist the designers with various aspects of wind action, including the overall structural loads and responses of the Tower shaft and the antenna superstructure, the local wind pressures on components of the exterior envelope, and winds in pedestrian areas. The designers of the Tower are the East China Architectural Design Institute (ECADI) and PT Menara Jakarta, Indonesia. Unfortunately, the project is halted due to the financial uncertainties in Indonesia. At the time of the stoppage, pile driving had been completed and slip forming of the concrete shaft of the Tower had begun. When completed, the Tower will exceed the height of the CN-Tower in Toronto, Canada by some 5 m.

• New & Renewable Energy
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• v.7 no.4
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• pp.42-49
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• 2011

The objective of this paper is to suggest a new method of a wind turbine performance test. The performance test of a wind turbine is generally carried out in a wind tunnel. The test needs not only a high-accuracy measuring system but also durable structure to withstand high speed turbine rotation and wind flow. Therefore, we tried turbine performance test using a towing tank to improve stability and reliability. Because a turbine rotates more slowly and generates more torque in the water than in the wind tunnel under similarity conditions. In this study, we developed turbine performance test systems and verified the turbine test method using a towing tank through comparing results of the wind tunnel and the towing tank test.

• New & Renewable Energy
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• v.4 no.2
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• pp.87-93
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• 2008

Wind tunnel test for the 12% scaled model of NREL Phase VI wind turbine was conducted in KARI low speed wind tunnel for $2006{\sim}2007$. The 1st and 2nd test was designed to find out the wind tunnel test method for the blade manufacturing accuracy and surface treatment method by using the composite and aluminum blades. And the 3rd test was designed to study the scale effect. The chord extension method which was used for Bo-105 40% scaled model was adapted for scale effect correction. Test results shows that the chord extension method works well for the torque slope but the maximum torque for scaled model is about 8% below than the real scale model. New correction method to correct this offset was proposed.

• Wind and Structures
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• v.1 no.4
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• pp.351-364
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• 1998

In wind tunnel experiments, the blockage effect is a very important factor which affects the test results significantly. A number of investigations into this problem, especially on the blockage correction of drag coefficient, have been carried out in the past. However, only a limited number of works have been reported on the wind tunnel blockage effect on wind-induced vibration although it is considered to be fairly important. This paper discusses the aerodynamic characteristics of the square model and square model with corner cut based on a series of the wind tunnel tests with various blockage ratios and angles of attack. From the test results, the aerodynamic behavior of square models with up to 10% blockage ratio are almost the same and square models with up to 10% blockage ratio can be tested as a group which behaves similarly.

• Wind and Structures
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• v.1 no.1
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• pp.77-109
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• 1998

An evaluation and comparison of seven of the world's major building codes and standards is conducted in this study, with specific discussion of their estimations of the alongwind, acrosswind, and torsional response, where applicable, for a given building. The codes and standards highlighted by this study are those of the United States, Japan, Australia, the United Kingdom, Canada, China and Europe. In addition, the responses predicted by using the measured power spectra of the alongwind, acrosswind and torsional responses for several building shapes tested in a wind tunnel are presented and a comparison between the response predicted by wind tunnel data and that estimated by some of the standards is conducted. This study serves not only as a comparison of the response estimates by international codes and standards, but also introduces a new set of wind tunnel data for validation of wind tunnel-based empirical expressions.

• Journal of the Korean Society of Industry Convergence
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• v.23 no.4_2
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• pp.637-644
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• 2020

Because suicide accidents sometimes were happened in grand bridges over rivers or sea water recently, it will be necessary that prevention measures be made preparation in advance from now on. Additional safety facilities must be needed in addition to existing safety facilities in such a way as this prevention measure. In order to make cable-stayed bridge safe on wind for additional safety facilities, main girder models with added safety facilities for wind-tunnel tests was made, and wind tunnel experiments was carried out to measure aerodynamic force coefficients. Also, wind-resistant analyses of 3D cable-stayed bridge were performed on the basis of wind-tunnel test results. From the wind experiments, force coefficients of main girder with added safety facilities were assessed, and it is known that there are little possibility of galloping and rotation of steel main girder. Finally, from the wind resistant analyses, it was concluded that wind-resistant safety of cable-stayed bridge was secured on wind speed 60.6m/sec.