• Wind and Structures
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• v.12 no.4
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• pp.333-347
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• 2009

Many tower-supported steel stacks have been constructed in Japan, primarily for economic reasons. However the dynamic behavior of these stacks under a strong wind is not well known and the wind load design standard for this type of a stack has not yet been formulated. In light of this situation, we carried out wind response observation of an operating tower-supported steel stack with and without a tuned-mass damper. The observation revealed the performance of the tuned-mass damper installed on the stack in order to control the wind-induced vibration. Based on the observed data, we performed a wind tunnel test of a specimen of the stack. In this paper we report the results of the wind tunnel test and some comparisons with the results of observation. Our findings are as follows: 1) the tuned-mass damper installed on the specimen in the wind tunnel test worked as well as the one on the observed stack, 2) the amplitude of the vortex-induced vibration of the specimen corresponded approximately to that of the observed stack, and 3) correlation between Scruton number and reduced amplitude, y/d, (y is amplitude, d is diameter) was confirmed by both the wind tunnel test and the observed results.

• 유체기계공업학회:학술대회논문집
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• 2006.08a
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• pp.37-40
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• 2006

Wind tunnel testings to develope tilt-rotor Smart Unmanned Aerial Vehicle (SUAV) were intensively performed. Small wind tunnel was used to find and evaluate design parameters and to fix general layout of configuration. The application of large tunnel with 40% scaled model is to collect performance and stability related aerodynamic data. During large scale model test wind tunnel is used as a tool to compare Flaperon types, to improve lift characteristics by using different height vortex generators and to alleviate nacelle separated flow effects on the wing.

• Journal of Korean Association for Spatial Structures
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• v.17 no.4
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• pp.103-113
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• 2017

Spatial Structure has suffered from a lot of damage due to the use of lightweight roofs. Among them, the damage caused by strong winds was the greatest, and the failure of the calculation of the wind load was the most frequent cause. It provides that wind tunnel test is used to calculate the wind load. However, it is often the case that the wind load is calculated based on the standard of wind load in the development design stage. Therefore based on this, the structure type and structural system and member design are often determined. Spatial structure is usually open at a certain area. The retractable roof structure should be operated with the open roof in some cases, so the wind load for the open shape should be considered, but it is not clear on the basis of the wind load standard. In this paper, the design wind pressure of a closed and retractable roof structure is calculated by KBC2016, AIJ2004, ASCE7-10, EN2005, and the applicability of wind pressure coefficient is compared with wind tunnel test.

• Wind and Structures
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• v.15 no.6
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• pp.495-508
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• 2012

The present paper is focused on the prediction of the acrosswind aeroelastic response of square tall buildings. In particular, a semi-analytical procedure is proposed based on the assumption that square tall buildings, for reduced velocities corresponding to operational conditions, do not experience vortex shedding resonance or galloping and fall in the range of positive aerodynamic damping. Under these conditions, aeroelastic wind tunnel tests can be unnecessary and the response can be correctly evaluated using wind tunnel tests on rigid models and analytical modeling of the aerodynamic damping. The proposed procedure consists of two phases. First, simultaneous measurements of the pressure time histories are carried out in the wind tunnel on rigid models, in order to obtain the aerodynamic forces. Then, aeroelastic forces are analytically evaluated and the structural response is computed through direct integration of the equations of motion considering the contribution of both the aerodynamic and aeroelastic forces. The procedure, which gives a conservative estimate of the aeroelastic response, has the advantage that aeroelastic tests are avoided, at least in the preliminary design phase.

• Transactions of the Korean Society for Noise and Vibration Engineering
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• v.18 no.6
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• pp.612-618
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• 2008

Microphone array beamforming method has been recognized as an important aeroacoustic research field and become a standard technique in localizing sound sources. This method also used in flight acoustic measurement, and especially, it is very useful when measure sounds inside the wind tunnel. In measuring sound which is inside the wind tunnel by traditional beamforming method, there are some errors caused by airstream. The speed and the propagation path of the sound changes as it travel through the airstream. This makes the error which the position of sound is changed a little bit to the down stream direction. In this paper, validation test has made about the correction equation for this wind effects of previous researches. And beamforming including shear layer correction was performed about a sound source in the anechoic open-jet wind tunnel.

• Proceedings of the KSME Conference
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• 2000.04b
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• pp.605-610
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• 2000

A series of wind tunnel test were conducted on Korean high speed train model to understand the flow physics around the vehicle related to the aerodynamic drag. For the wind tunnel test on high-speed ground vehicle, a moving ground simulation is necessary to predict the aerodynamic drag accurately. So, the models were tested in three wind tunnels with various ground simulation facility including moving belt ground plane system and tangential blowing system. The test results including measured aerodynamic drag and flow visualization showed that a tangential blowing method can be an alternative ground simulation method in short time using conventional wind tunnel.

• Proceedings of the Computational Structural Engineering Institute Conference
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• 2007.04a
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• pp.739-744
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• 2007

Wind loads for cladding can be estimated using the maximum wind pressure including gust effects from wind-tunnel tests. However, when estimating the maximum wind pressure with gust effects, wind pressure coefficients for cladding would be different according to the averaging time of wind pressures, In the paper, for wind pressures obtained from wind-tunnel tests for apartment buildings, whose window panes were damaged by actual strong wind, it was investigated how pressure coefficients varied according to the size of cladding and averaging time using TVL method of Lawson. In result, it was found that the lesser the size of cladding and averaging time were, the larger pressure coefficients became. Accordingly, to estimate wind loads for cladding of apartment buildings and design it, the averaging time of wind pressures should be considered properly.

• Wind and Structures
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• v.17 no.6
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• pp.565-587
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• 2013

Obvious vortex induced vibration (VIV) was observed during section model wind tunnel tests for a single main cable suspension bridge. An optimized section configuration was found for mitigating excessive amplitude of vibration which is much larger than the one prescribed by Chinese code. In order to verify the maximum amplitude of VIV for optimized girder, a full bridge aeroelastic model wind tunnel test was carried out. The differences between section and full aeroelastic model testing results were discussed. The maximum amplitude derived from section model tests was first interpreted into prototype with a linear VIV approach by considering partial or imperfect correlation of vortex-induced aerodynamic force along span based on Scanlan's semi-empirical linear model. A good consistency between section model and full bridge model was found only by considering the correlation of vortex-induced force along span.

• Wind and Structures
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• v.16 no.5
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• pp.491-515
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• 2013

Wind pressure characteristics on a double tower high-rise structure, which is disturbed by surrounding buildings, were investigated using large eddy simulation (LES) and 1:300 scale wind tunnel experiments. The computational simulation technique and wind tunnel experimental technique were described in detail initially. Comparisons of computational results with the experimental data have subsequently been carried out to validate the reliability of LES. Comparisons have been performed in detail for the mean and fluctuating pressure coefficients. Detailed explanations of each comparison were given in the paper. To study further on the pressure coefficients on the building surfaces, parametric studies on shape coefficient and spatial correlation were performed and investigated. The numerical and experimental results presented in this paper advance understanding on wind field around buildings and the application of LES and wind tunnel tests.

• Wind and Structures
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• v.10 no.5
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• pp.401-420
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• 2007

Field measurements of the wind-induced response of two residential reinforced concrete buildings, among the tallest in the world, have been performed during two typhoons. Natural periods and damping values have been determined and compared with other field measurements and empirical predictors. Suitable and common empirical predictors of natural period and structural damping have been obtained that describe the trend of tall, reinforced concrete buildings whose structural vibrations have been measured in the collection of studies in Hong Kong compiled by the authors. This data is especially important as the amount of information known about the dynamic parameters of buildings of these heights is limited. Effects of the variation of the natural period and damping values on the alongwind response of a tall building for serviceability-level wind conditions have been profiled using the gust response factor approach. When using this approach on these two buildings, the often overestimated natural periods and structural damping values suggested by empirical predictors tended to offset each other. Gust response factors calculated using the natural periods and structural damping values measured in the field were smaller than if calculated using design-stage values.