• 한국항공운항학회:학술대회논문집
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• 2016.05a
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• pp.217-220
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• 2016

본 논문은 고공강하 훈련장치인 수직 풍동 장비의 현황 및 실내 스포츠로서의 활용방안에 대하여 논의하였다. 고공강하는 군의 특수낙하훈련이나 일반인의 스포츠 레저 활동으로 이루어지며. 극한의 스포츠를 즐기려는 사람들이 증가하하여 외국의 경우에는 활성화되어 있는 스포츠의 하나이다. 특히 북유럽 지역에서는 겨울에 실내 고공낙하를 위해서 사용할 수 있는 장비로서 수직 풍동이 사용된다. 수직풍동은 개방식과 폐쇄 회로형으로 개발되어 활용되고 있으며, 최근에는 놀이시설의 일환으로 회로형의 고가수직풍동이 많이 설치되는 추세에 있다. 수직풍동은 고공강하 체험 및 훈련을 위한 장비로서 미래에는 더욱 많이 이용되게 될 것으로 보인다. 극한 스포츠를 즐기려는 사람들이 증가하고 오락기구로서도 매력적인 장비이기 때문에 앞으로 국내에서도 이러한 시설의 설치 및 활용이 이루어질 것이다.

• Proceedings of the KSME Conference
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• 2000.11b
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• pp.447-452
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• 2000

In this study, the design of Free-Fall Simulator was carried out using concept of vertical wind tunnel. Free-Fall Simulator is not an experimental equipment but a training equipment. Therefore Free-Fall Simulator needs a large training section compared with test section of wind tunnel and has critical limit of height. These limits bring about the difficulty of design for a return passage. Due to small area ratio, the downstream flow of training section with high speed is not decelerated adequately to the fan section. High-speed flow leads to great losses in the small area ratio diffuser and corner. So design of diffusers and corners located between training section and fan section has a great effect on the Free-Fall Simulator performance. This study used an estimation method of subsonic wind tunnel performance. It considered each section of Free-Fall Simulator as an independent section. Therefore loss of one section didn't affect loss of other sections. Because losses of corner with vane and $1^{st}$ diffuser are most parts of overall Free-Fall Simulator, this study focused on the design of these sections.

• Journal of Advanced Marine Engineering and Technology
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• v.40 no.4
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• pp.330-335
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• 2016

In this study, aerodynamic characteristics of the blades of a helical-type vertical axis wind turbine(VAWT) have been investigated. For this purpose, a 100-W helical-type vertical axis wind turbine was designed using a design formulae, and a 3D computational fluid dynamics analysis was performed considering wind tunnel test conditions. Through the results of the analysis, the aerodynamic power output and flow characteristics of a helical blade were confirmed. In order to validate the aerodynamic power output obtained through the analysis, a wind tunnel test was performed by using a full-scale helical-type vertical axis wind turbine. The 3D analysis technique was validated by comparing its results with those obtained from the wind tunnel test.

• Journal of the Korean Society for Aeronautical & Space Sciences
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• v.46 no.2
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• pp.114-123
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• 2018

Wind power tower (WPT) has been used to augment the performance of vertical axis wind turbine (VAWT). However, the performance of the WPT depends on several design parameters, such as inner and outer radius, or number of guide walls. Therefore, an experimental study was conducted to investigate efficient design parameters on the WPT. A wind tunnel was utilized and its test section dimension was 2m height and 2.2m width. One story model of the WPT was manufactured with seven guide walls and a VAWT was installed within the WPT. Three different sizes of guide walls were applied to test with various design parameters. The power coefficients were measured along the azimuthal direction in a state of equal inlet velocity in order to compare its performance relatively. The experimental results showed that the gap between the inner radius of the WPT and the rotating radius of the VAWT was a major parameter to improve the performance of VAWT within the WPT.

• Journal of the Korean Society for Aeronautical & Space Sciences
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• v.40 no.8
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• pp.711-717
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• 2012

During the conceptual design phase of a light sport aircraft, the wind tunnel tests were conducted to investigate the static stability of newly-designed configuration. The 1/5 scale-down wind tunnel model consisted of fuselage, main wing, vertical tail and horizontal tail. The main wing and tails were able to be attached or detached from the fuselage. The aerodynamic forces and moments acting on the 6 different configurations compounding each component were measured by using the internal balance system and their static stability derivatives were derived. With these experimental data, the baseline lift and drag characteristics as well as the effects of each component to the longitudinal, directional and lateral static stability were quantitatively analyzed.

• Transactions of the Korean Society of Mechanical Engineers A
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• v.35 no.12
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• pp.1599-1606
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• 2011

It is possible to study the load characteristics of full-scale hingeless rotor with the changing of physical smallscaled configurations such as rectangular and paddle blades, and metal and composite hubs. In this study, a static test, and a ground and wind-tunnel test were carried out using small-scale rotor models. The static test was carried out to confirm structural stiffness, characteristics of inertia, natural frequency, and damping ratio of rotors, and the ground and wind-tunnel test was carried out to confirm the stability and aerodynamic characteristics under hovering and forward flight conditions. According to the test results, the vertical load in the case of a combination of a small composite hub with paddle blades was higher than that in the case of a metal hub with paddle blades at same condition. Further, it was confirmed that the restraint of the combination of composite hub can be more flexible than the metal hub for the motion of paddle blades.

• Journal of Korean Society of Steel Construction
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• v.20 no.6
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• pp.741-750
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• 2008

The aim of this study was to analyze the aerodynamic properties of the composite cable-stayed bridge by conducting three-dimensional wind tunnel tests. Focusing on the improved section of the bridge in the two-dimensional wind tunnel tests, the bridge's aerodynamic stability was estimated based on the angles of attack and the wind angles. The aerodynamic properties of vertical galloping, torsion galloping,and torsion flutter were also estimated based on the design wind velocity, and because much of the cable-stayed bridge was constructed using FCM, it was not sufficiently stiff during the bridge's construction. Therefore,the experience progressed by stages: from the full stage to the tow stage, and until the bridge became a single tower. Since the original plane was designed to be a steel box girder, the aerodynamic properties of the steel-box-type and composite-type girder could be compared. The results of this study can be utilized as basic data regarding the aerodynamic properties of medium-length and short composite cable-stayed bridges.

• Journal of the Korea Academia-Industrial cooperation Society
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• v.15 no.3
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• pp.1272-1278
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• 2014

In this experimental study for the current growing offshore wind, a wind tunnel test was conducted to examine the performance of the vertical-type cross-flow wind turbine power generation system. Due to the limited size of the test section of the wind tunnel, the inlet guide vane of the original wind power generation was scaled down to about 1/5 and the turbine impeller diameter was also reduced to 1/2 of the prototype impeller. The number of the impeller blade is another important parameter to the output power of the wind power generation system and the number was varied 8 and 16. From the analysis of the experimental result, the output brake power of the model wind turbine was measured as 278watts with the 16-blade at 12 m/s of the rated wind speed and the rated brake power of the prototype wind turbine is calculated to 3.9kW at the rated operating condition.

• 한국방재학회:학술대회논문집
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• 2007.02a
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• pp.445-448
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• 2007

교량의 플러터 발생풍속을 예측할 경우에는 주로 주형의 2차원 단면실험을 통하여 추정하고, 전체교량의 3차원 모형실험을 통하여 확인하게 된다. 주형단면의 2차원 단면모형 실험에서는 교량거더의 수직방향과 비틀림 방향의 2자유도계로 간략화하여 구조물의 거동을 살펴보게 된다. 전산풍공학적 방법에 의하여 구조물의 공기력을 산정하는 방법은 기존에 주로 사용되던 풍동실험을 대치하는 방법으로 개발되고 있으며, 교량의 플리터 발생풍속 예측을 위한 산정기법 역시 다양하다. 본 논문에서는 유사한 형상비를 가지는 $\pi$형 단면 거더의 플러터 발생풍속을 비교하였으며, 교량단면의 2차원 단면실험을 통하여 그 결과값을 비교, 검토하였다.

• Journal of Aerospace System Engineering
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• v.11 no.6
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• pp.10-16
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• 2017

In order to improve the safety of the multi-copter, Korea Aerospace Research Institute (KARI) performed a wind-tunnel test using an octocopter with the maximum takeoff weight (MTOW) of 28 kg. The wind-tunnel test was performed with three different RPM ranges, 3,500, 4,500 and 5,500 rpm, and three different wind speeds, 3.5, 5 and 7 m/sec. The tested range of the angle of attacks was $-40^{\circ}$ to $20^{\circ}degree$ and ${\pm}90^{\circ}degree$. Vortex ring state (VRS) of the tested multi-copter was located around the vertical descending speed of 6 m/sec and the decrement of thrust was about 13 % at the time of testing. Compared with the single propeller wind-tunnel test result, the propeller efficiency of the octocopter dropped to 10 to 15% depending on the propeller RPM. It is hypothesized that the obtained aerodynamic characteristics by the wind-tunnel test will be used to improve the performance and wind resistance of the multi-copter.