• 한국항공운항학회지
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• 제13권4호
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• pp.92-99
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• 2005

A closed-circuit type wind tunnel is designed, which has a test section with the dimensions $1.2(W){\times}1.2(H){\times}3.4(L)$. A subsonic wind tunnel is designed to improves educational circumstances and promote ground tests. It is constituted of an exchangeable test section, first and second diffusers, a fan, a settling chamber, a contraction, and 4 corners. The maximum velocity in the test section is 70m/s and the contraction ratio is 6.25:1. Input power in the wind tunnel is about 96.1 kw (128.8 hp) and its energy ratio is 3.89. It has the dimension of about $7.4(W){\times}3.6(H){\times}21.7m(L)$. The wind tunnel designed in this investigation will be an effective educational and investigational equipment.

• 한국신재생에너지학회:학술대회논문집
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• 한국신재생에너지학회 2011년도 추계학술대회 초록집
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• pp.33.2-33.2
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• 2011

The 'NREL Phase VI' model with a 10.06m diameter was tested in the NASA Ames tunnel to make a reference data of the computational models. The test was conducted at the one rotational speed, blade tip speed 38m/s and the Reynolds number of the sectional airfoils in that test was around 1E6. The 1/5 scale down model of the 'NREL Phase VI' model was used in this paper to study the power characteristics in low Reynolds number region, 0.1E6 ~ 0.4E6 which is achievable range for the conventional wind tunnel facilities. The torque generated by the blade was directly measured by using the torque sensor installed in the rotating axis for a given wind speed and rotational speed. The power characteristics below the stall condition, lambda > 4, was presented in this paper. The power coefficient is very low in the condition below the Re. 0.2E6 and rapidly increases as the Re. increases. And it still increases but the variation is not so big in the condition above the Re. 0.3E6. This results shows that to study the performance of the wind turbine blade by using the scaled down model, the Re. should be larger than the 0.3E6.

• 한국생산제조학회지
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• 제24권3호
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• pp.355-362
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• 2015

Test procedure for the design verification of wind turbine pitch and yaw bearings has been developed. Test items were selected to evaluate operational reliability of pitch and yaw bearings by considering loading and operational conditions, and by analyzing the design criteria of pitch and yaw bearings. The developed test items consisted of preliminary test, fatigue load test, extreme load test, low temperature environmental test and dismantling inspection after all the test were completed. Because it reflects the actual operational conditions of the pitch and yaw bearings, the developed test procedure has high reliability and can verify the basic design considerations in the international standard and guidelines.

• 한국방재안전학회논문집
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• 제6권2호
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• pp.49-56
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• 2013

본 논문에서는 재난변동풍하중을 받는 고층건물의 예비설계과정에서 필요로 하는 자료를 얻기 위하여 경계층풍동 실험을 실시했다. 먼저 본 실험에 앞서 경계층풍동내의 자연풍을 얻기 위하여 확산장치를 이용했고, 이로부터 평균풍속 수직분포, 난류강도, 파워스펙트럼으로 입증했으며, 이 후 변장비 1:2 강체모형을 이용 경계층풍동실험을 실시한 결과로부터 다음과 같은 결론을 얻을 수 있었다. 1. 경계층풍동에서의 평균풍속 및 난류강도의 수직분포가 자연풍과 같이 잘 실현되었다. 2. 변동풍속 스펙트럼은 Von Karman spectrum과 비교한 결과 잘 일치했다. 3. 변동압력 스펙트럼에서 풍상면의 피크분포는 0.01-0.1 Hz영역에서 발생했고, 풍후면은 0.1 Hz영역에서 발생했다. 4. 자기상관계수는 재난변동풍하중의 작용시간이 증가하면 정성확률과정으로 분포하는 사실을 알 수 있었다.

• Wind and Structures
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• 제26권2호
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• pp.75-87
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• 2018

A large number of low-rise buildings experienced serious roof covering failures under strong wind while few suffered structural damage. Clay and concrete tiles are two main kinds of roof covering. For the tile roof system, few researches were carried out based on Finite Element (FE) analysis due to the difficulty in the simulation of the interface between the tiles and the roof sheathing (the bonding materials, foam or mortar). In this paper, the FE analysis of a single clay or concrete tile with foam-set or mortar-set were built with the interface simulated by the equivalent nonlinear springs based on the mechanical uplift and displacement tests, and they were expanded into the whole roof. A detailed wind tunnel test was carried out at Tongji University to acquire the wind loads on these two kinds of roof tiles, and then the test data were fed into the FE analysis. For the purpose of validation and calibration, the results of FE analysis were compared with the full-scale performance ofthe tile roofs under simulated strong wind impact through one-of-a-kind Wall of Wind (WoW) apparatus at Florida International University. The results are consistent with the WoW test that the roof of concrete tiles with mortar-set provided the highest resistance, and the material defects or improper construction practices are the key factors to induce the roof tiles' failure. Meanwhile, the staggered setting of concrete tiles would help develop an interlocking mechanism between the tiles and increase their resistance.

• 한국산학기술학회논문지
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• 제22권5호
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• pp.98-107
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• 2021

차기군수지원함(AOE-II) 풍향풍속계 장비에 대해서 항해시운전평가 결과, 함의 우현에서는 40~90도 부근, 좌현에서는 270~320도 부근에서 풍향풍속 검출기 움직임 오작동 현상이 발생되었다. 위의 현상에 대한 원인을 분석하고 개선하는 것이 본 연구의 목적이었다. 원인 추정으로 풍향풍속 검출기가 마스트 구조물에 가려져서 불어오는 바람의 직접적인 영향을 받지 않게 되고, 마스트 구조물 뒤쪽으로 와류 기류가 형성되어 움직임 오작동 현상을 발생시켰다고 추정하였다. 위의 문제를 해결하기 위해서 신규 설치되는 마스트 야드에 풍향풍속 검출기를 이동 설치하는 방안을 검토하였다. 진동 해석을 실시하여 진동 영향성을 검토 후 신규 마스트 야드에 풍향풍속 검출기를 설치하여 항해시운전평가로 검증하였다. 개선 방안이 일부 유효하여, 신규 마스트 야드에서 풍향풍속 검출기 위치를 마스트와 이격하여 이동 설치 후 항해시운전평가로 다시 검증하였다. 풍향풍속 검출기 움직임 오작동 현상이 더 이상 발생하지 않아서 적절한 개선방안으로 확인되었다.

• Structural Engineering and Mechanics
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• 제56권4호
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• pp.625-648
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• 2015

Modern super-tall buildings are more sensitive to strong winds. The evaluation of wind loads for the design of these buildings is of primary importance. A direct monitoring of wind forces acting on super-tall structures is quite difficult to be realized. Indirect measurements interpreted by inverse techniques are therefore favourable since dynamic response measurements are easier to be carried out. To this end, a Kalman filtering based inverse approach is developed in this study so as to estimate the wind loads on super-tall buildings based on limited structural responses. The optimum solution of Kalman filter gain by solving the Riccati equation is used to update the identification accuracy of external loads. The feasibility of the developed estimation method is investigated through the wind tunnel test of a typical super-tall building by using a Synchronous Multi-Pressure Scanning System. The effects of crucial factors such as the type of wind-induced response, the covariance matrix of noise, errors of structural modal parameters and levels of noise involved in the measurements on the wind load estimations are examined through detailed parametric study. The effects of the number of vibration modes on the identification quality are studied and discussed in detail. The made observations indicate that the proposed inverse approach is an effective tool for predicting the wind loads on super-tall buildings.

• Wind and Structures
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• 제22권1호
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• pp.17-41
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• 2016

To address the uncertainty of the flight trajectories caused by the turbulence and gustiness of the wind field over the roof and in the wake of a building, a 3-D probabilistic trajectory model of flat-type wind-borne debris is developed in this study. The core of this methodology is a 6 degree-of-freedom deterministic model, derived from the governing equations of motion of the debris, and a Monte Carlo simulation engine used to account for the uncertainty resulting from vertical and lateral gust wind velocity components. The influence of several parameters, including initial wind speed, time step, gust sampling frequency, number of Monte Carlo simulations, and the extreme gust factor, on the accuracy of the proposed model is examined. For the purpose of validation and calibration, the simulated results from the 3-D probabilistic trajectory model are compared against the available wind tunnel test data. Results show that the maximum relative error between the simulated and wind tunnel test results of the average longitudinal position is about 20%, implying that the probabilistic model provides a reliable and effective means to predict the 3-D flight of the plate-type wind-borne debris.

• Wind and Structures
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• 제34권1호
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• pp.73-80
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• 2022

This paper presents a study on amplitude-dependent self-excited aerodynamic forces of a 5:1 rectangular cylinder through free vibration wind tunnel test. The sectional model was spring-supported in a single degree of freedom (SDOF) in torsion, and it is found that the amplitude of the free vibration cylinder model was not divergent in the post-flutter stage and was instead of various stable amplitudes varying with the wind speed. The amplitude-dependent aerodynamic damping is determined using Hilbert Transform of response time histories at different wind speeds in a smooth flow. An approach is proposed to extract aerodynamic derivatives as nonlinear functions of the amplitude of torsional motion at various reduced wind speeds. The results show that the magnitude of A2^*, which is related to the negative aerodynamic damping, increases with increasing wind speed but decreases with vibration amplitude, and the magnitude of A3^* also increases with increasing wind speed but keeps stable with the changing amplitude. The amplitude-dependent aerodynamic derivatives derived from the tests can also be used to estimate the post-flutter response of 5:1 rectangular cylinders with different dynamic parameters via traditional flutter analysis.

• 한국정밀공학회:학술대회논문집
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• 한국정밀공학회 2006년도 추계학술대회 논문집
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• pp.211-212
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• 2006