• 한국군사과학기술학회지
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• 제22권3호
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• pp.353-359
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• 2019

In this study, a aerodynamic loads prediction to design a deploying device of folded fin was introduced. In general, resultant flow conditions around the fin are used to obtain deploying moments and required energy. However, when it comes to the air vehicles launched from a mobile platform, more specific flow conditions can be provided. With the conditions, the design criteria can be calculated more realistically. In this study, therefore, aerodynamic moments induced by aerodynamic loads and energy required in deployment were calculated using wind-over-deck(WOD) velocity, combination of a platform velocity and a wind velocity. For the calculation, wind tunnel test was conducted on various angle of attack, side slip angles, and folding angles. It was found that the aerodynamic moments and the energy required in deployment using the non-uniform flow due to the velocity components were less than those using the uniform flow without the components.

• 한국철도학회:학술대회논문집
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• 한국철도학회 2011년도 정기총회 및 추계학술대회 논문집
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• pp.88-93
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• 2011

The aerodynamic drag characteristics of HEMU-400X which has been being developed for the maximum speed of 430km/h were analyzed experimentally as the variations of the pantograph cover configurations to reduce the acoustic noise and the aerodynamic drag of the pantograph system. The wind tunnel tests were performed with three pantograph cover models upon 1/20 scaled 5-car model of HEMU-400X. Two kinds of wedge shapes which induce up-flow in the vicinity of the pantograph and one cone shape which reduces the whole train drag were used in order to compare the aerodynamic characteristics as the pantograph cover shape changes. The each axial force of 5 each car was measured at a time with the test velocities, 30, 40, 50, 60m/s. Through the wind tunnel test the base drag forces of HEMU-400x model and the forces by the pantograph cover on the train model were investigated and the aerodynamic drag characteristics of the train model by the pantograph cover configurations were analyzed.

• 대한기계학회논문집A
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• 제35권1호
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• pp.91-98
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• 2011

측풍 시 AREX 열차에 가해지는 공기역학적 하중을 측정하기 위하여 풍동시험이 수행되었다. 5% 축소 시험 모델은 연결부, 하부 및 대차부 등을 포함하여 가능한한 자세하게 모델링되었다. 시험에 사용된 풍동은 폭 4m $\times$ 높이 3m 의 시험부를 가진 한국항공우주연구원(KARI)의 중형 아음속 풍동이다. 두 종류의 선로 모형에 놓여진 열차 모델에 가해지는 공기역학적 하중과 모멘트는 요각에 따라 도시되었으며, 실험 조건에 따른 공력 계수의 특성이 분석되었다.

• 한국군사과학기술학회지
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• 제7권3호
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• pp.21-29
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• 2004

Numerical analysis of aerodynamic heating for KPSAM is performed using aerodynamic heating model suitable to KPSAM, which has complex flow field resulting from the spike attached to the dome, such as large separation area and the strong shock/boundary layer interaction region around reattachment point on the dome. The aerodynamic heating model is validated and modified through the comparison between the flight test measurement and the thermal analysis results. TFD temperature sensors are installed on the dome to measure surface temperature during the flight. Computation results, obtained from the heat transfer analysis on the sensors, agree well with flight test data. The aerodynamic heating model provides heat transfer rate into surface as a boundary condition of unsteady 1D/axisymmetric thermal analysis on the missile structure. The axisymmetric thermal analysis using FLUENT is more versatile than the 1D analysis and can be applied to the heating problem related with complex structures and multi-dimensional heat transfer problems such as prediction of temperature rise at contact surface of different materials.

• Wind and Structures
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• 제6권1호
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• pp.53-70
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• 2003

Tsing Ma Bridge in Hong Kong is the longest suspension bridge in the world carrying both highway and railway. It has two H-shape concrete towers, each of which is composed of two reinforced concrete legs and four deep transverse prestressed concrete beams. A series of wind tunnel tests have been performed to measure the aerodynamic coefficients of the tower legs and transverse beams in various arrangements. A 1:100 scaled 3D rigid model of the full bridge tower assembled from various tower components has been constructed for different test cases. The aerodynamic coefficients of the lower and upper segments of the windward and leeward tower legs and those of the transverse beams at different levels, with and without the dummy bridge deck model, were measured as a function of yaw wind angle. The effects of wind interference among the tower components and the influence of the bridge deck on the tower aerodynamic coefficients were also investigated. The results achieved can be used as the pertinent data for the comparison of the computed and field-measured fully coupled buffeting responses of the entire bridge under yaw winds.

• International Journal of Aeronautical and Space Sciences
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• 제16권3호
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• pp.425-436
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• 2015

This paper presents the procedures used for estimating the stability and control derivatives of a general aviation canard aircraft from flight data. The maximum likelihood estimation method which accounts for both process and measurement noise was used for the flight data analysis of a four seat canard aircraft, the Firefly. Without relying on the parameter estimation method, several aerodynamic derivatives were obtained by analyzing the steady state flight data. A wind tunnel test, a flight test of a 1/4 scaled remotely controlled model aircraft, and the prediction of aerodynamic coefficients using the USAF Stability and Control Digital Data Compendium (DATCOM), Advanced Aircraft Analysis (AAA), and Computer Fluid Dynamics (CFD) were performed during the development phase of the Firefly and the results were compared with flight determined derivatives of a full scaled flight prototype. A correlation between the results from each method could be used for the design of the canard aircraft as well as for building the aerodynamic database.

• Wind and Structures
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• 제31권3호
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• pp.209-216
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• 2020

Aiming at the wind-resistant design of a sea-crossing arch bridge, the static aerodynamic coefficients of its girder (composed of stretches of π-shaped cross-section and box cross-section) were studied by using computational fluid dynamics (CFD) numerical simulation and wind tunnel test. Based on the comparison between numerical simulation, wind tunnel test and specification recommendation, a combined calculation method for the horizontal force coefficient of intermediate and small span bridges is proposed. The results show that the two-dimensional CFD numerical simulations of the individual cross sections are sufficient to meet the accuracy requirements of engineering practice.

• 한국소음진동공학회:학술대회논문집
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• 한국소음진동공학회 2001년도 추계학술대회논문집 II
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• pp.1207-1214
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• 2001

The paper deals with the computational approach in analysis and design of pantograph panhead strips of high-speed railway in aerodynamic and aeroacoustic concerns. Pantograph is an equipment such that the electric power is supplied from catenary system to train. Due to the nature of complexity in high-speed fluid flow, turbulence and downstream vortices result in the instability in the aerodynamic contact between panhead strips and catenary system, and consequently generate the considerable levels of flow-induced sound. In this paper, based on the preceding low speed wind-tunnel test and simulations, the aerodynamic and aeroacoustic characteristics in low speed are analyzed.

• 한국가시화정보학회지
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• 제17권2호
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• pp.32-38
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• 2019

A comparison study between computational-fluid-dynamics simulation and wind tunnel test for a megawatt-class wind turbine is conducted. For the study, flow-field in wake, basic aerodynamic performance, and effect of the yaw error for a 1/86 scaled-down model of the NREL offshore 5 MW wind turbine are numerically calculated using commercial software "FloEFD" with $k-{\varepsilon}$ turbulence model. The computed results are compared to the wind tunnel test performed by the constant-velocity mode for the model. It is shown that discrepancy are found between the two results at lower tip-speed ratio and higher yaw angle, however, the velocity-defection distribution in the wake, the torque coefficient at moderated and high tip-speed ratios are in good agreement with the wind tunnel test.

• 대한기계학회논문집B
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• 제28권6호
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• pp.734-739
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• 2004

The aerodynamic effect on platform during the train passage, the results of field test on the high-speed railway platform are discussed and the whole test results and conclusions are synthesized. The field test for the high-speed railway have been conducted on the Osong temporary platform in the newly constructed Seoul-Busan high-speed line and total 12 measurements have been conducted for G7 train and KTX train. The results shows that the high-speed trains have similar aerodynamic characteristics and have far better characteristics referring to the conventional trains such as Saemaul and Mugungwha trains. To discuss the actual aerodynamic effects on the platform at its own operational speed, Beaufort wind scale have been introduced and the criteria for the safety on railway platform has also been discussed.