• Wind and Structures
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• v.32 no.5
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• pp.509-520
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• 2021

The streamlined box is a common type of girders for long-span suspension bridges. Spanning deep canyons, long-span bridges are frequently attacked by strong winds with large angles of attack. In this situation, the flow field around the streamlined box changes significantly, leading to reduction of the flutter performance. The wind fairings have different effects on the flutter performance. Therefore, this study examines the flutter performance of box girders with different wind fairings at large angles of attack. Computational fluid dynamics (CFD) simulations were carried out to extract the flutter derivatives, and the critical flutter state of a long-span bridge was determined. Further comparisons of the wind fairings were investigated by a rapid method which is related to the input energy by the aerodynamic force. The results show that a reasonable type of wind fairings could improve the flutter performance of long-span bridges at large angles of attack. For the torsional flutter instability, the wind fairings weaken the adverse effect of the vortex attaching to the girder, and a sharper one could achieve a better result. According to the input energies on the girder with different wind fairings, the symmetrical wind fairings are more beneficial to the flutter performance

• Wind and Structures
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• v.27 no.4
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• pp.255-267
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• 2018

This paper investigated the wind-snow flow around the bogie region of a high-speed train under crosswinds using a coupled numerical method of the unsteady Realizable $k-{\varepsilon}$ turbulence model and discrete phase model (DPM). The flow features around the bogie region were discussed and the influence of bogie fairing height on the snow accumulation on the bogie was also analyzed. Here the high-speed train was running at a speed of 200 km/h in a natural environment with the crosswind speed of 15 m/s. The mesh resolution and methodology for CFD analysis were validated against wind tunnel experiments. The results show that large negative pressure occurs locally on the bottom of wheels, electric motors, gear covers, while the positive pressure occurs locally on those windward surfaces. The airflow travels through the complex bogie and flows towards the rear bogie plate, causing a backflow in the upper space of the bogie region. The snow particles mainly accumulate on the wheels, electric motors, windward sides of gear covers, side fairings and back plate of the bogie. Longer side fairings increase the snow accumulation on the bogie, especially on the back plate, side fairings and brake clamps. However, the fairing height shows little impact on snow accumulation on the upper region of the bogie. Compared to short side fairings, a full length side fairing model contributes to more than two times of snow accumulation on the brake clamps, and more than 20% on the whole bogie.

• 유체기계공업학회:학술대회논문집
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• 2006.08a
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• pp.113-116
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• 2006

In this paper, the fairing effects on the aerodynamics stability of basic plate-girder sections are investigated trough wind tunnel tests. As basis sections, two types of $\pi$-type shape sections with aspect ratios(D/B) of 1/5 and 1/10 are employed as the basic sections. And three types of triangular fairings are applied such as right-angled triangle(F1), inverted right-angled triangle(F2) and regular triangle(F3). The effects of attack angle on the dynamic response of each section are also investigated. As the results of experiments, fairings F2 is most effective to suppress flutter phenomenon or vortex induced vibration among three types of fairings.

• Proceedings of the Korean Society For Composite Materials Conference
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• 2002.10a
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• pp.193-197
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• 2002

Polyurethane casting wing fairings included in F-5E/F 15% spar kit are to be installed on aircraft wing surfaces and used for compensating the changes of the aerodynamic configuration by the leading edge extension fairings. These fairing are mandatory items in repairing wing areas and was imported from foreign supplier with long term delivery and high cost. Accordingly, local manufacturing is necessary to get rid of above disadvantages such as long term delivery and high cost. Basic properties test of specimen to be developed and part's requirements after localization was taken and its values were similar or higher when comparing with the original's even in low temp test at -55C. Casting mold process was used to manufacture the polyurethane fairings and its demensional stability ＆ physical condition was proper and met to the related specification and drawing's requirements

• Journal of the Korean Society for Aeronautical & Space Sciences
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• v.33 no.6
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• pp.76-82
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• 2005

Cable fairings of guided missiles are generally used for protection of electric cables under aerodynamic heating and mechanical loading. The stress distributions between a cable fairing and missile main body along a cable fairing are necessary for its design. In this paper, a method for bonding stress and strength analysis of a cable fairing has been investigated and its computer program developed. Tensile and three-point bending tests of generally used bonding materials were also conducted to supply basic material properties for design of cable fairings.

• Journal of the Korean Society for Aeronautical & Space Sciences
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• v.39 no.4
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• pp.289-296
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• 2011

In this study, fairing configurations for an aircraft are designed and the aerodynamic analyses of the fairings are performed to find the best choice for the aircraft. Fairings considered are wing-tip fairing and wing-body fairing. Wing alone analyses are done for the wing-tip faring selection, while wing-body-tail analyses are done for the wing-body fairing selection. A 3-D RANS solver with Menter's ${\kappa}-{\omega}$ SST turbulence model are used for the aerodynamic analyses. The effects on the drag of the aircraft are examined by comparing the analysis results with and without the farings.

• Wind and Structures
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• v.23 no.1
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• pp.45-57
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• 2016

Open-cross-section composite beam (OCB) tends to suffer vortex-induced vibration (VIV) due to its bluff aerodynamic shape. A cable-stayed bridge equipped with typical OCB is taken as an example in this paper to conduct sectional model wind tunnel test. Vortex-induced vibration is observed and maximum vibration amplitudes are obtained. CFD approach is employed to calculate the flow field around original cross sections in service stage and construction stage, as well as sections added with three different countermeasures: splitters, slabs and wind fairings. Results show that flow separate on the upstream edge and cause vortex shedding on original section. Splitters can only smooth the flow field on the upper surface, while slabs cannot smooth flow field on the upper or lower surface too much. Thus, splitters or slabs cannot serve as valid aerodynamic means. Wind tunnel test results show that VIV can only be mitigated when wind fairings are mounted, by which the flow field above and below the bridge deck are accelerated simultaneously.

• International Journal of Aeronautical and Space Sciences
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• v.2 no.1
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• pp.103-109
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• 2001

Productivity enhancement program of wind tunnel testing has begun at Korea Aerospace Research Institute Low Speed Wind Tunnel (KARI LSWT). A previous test record of a canard airplane model was adopted to examine the current status of wind tunnel testing efficiency. The time consumed to perform testing activities from the model preparation to data collection was broken down and the results were compared with those of the recent Boeing low speed test result. The efforts to improve the wind tunnel productivity consisted of the installation of mini crane underneath of test section, fabricating lift device for image fairings, model configuration changing rigs and the modifications of external balance system. Time reductions for changing strut interface platform and installation of image fairings. These effects showed more than 70% improvement over the previous test time. Integration of the new and modified systems will improve productivity of wind tunnel testing in KARI LSWT.

• Aerospace Engineering and Technology
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• v.2 no.1
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• pp.171-181
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• 2003

The nose fairings of KSR-III are designed to be separated from the rocket by explosive force at the mission altitude to expose the payload. Adequate amount of separation force should be imposed to allow safe separation without collision between the fairings and the rocket, and the separation device was designed for the separation at very high altitude where almost no air load was expected. As the development of KSR-III goes on, several design changes have made and lower separation altitude of 45km is expected as a result. Under these circumstances, it is required to determine if the nose fairings can be separated without collision with much severer air load than for the design condition. In this study, the 6-DOF motion analysis program, PASEM, which was developed to predict the strap-on booster separation, is modified to simulate the pivotal motion of the fairings at early stages of separation. The accuracy of pivot motion simulation is validated by comparison with the results of ground test and the accurate separation conditions are deduced from it. Trajectory simulations are performed to see if separation without collision is possible with varying angle of attack, direction of gravity, and the effect of gust. It is also found that reducing the separation angle of the clamshell hinge from 60 degrees to 40 degrees can enhance separation safety and separation at lower altitude of 40km can be done without collision.

• Aerospace Engineering and Technology
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• v.10 no.2
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• pp.82-86
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• 2011

This paper presents an RF Electric field assessment at 2.290 [GHz] inside launcher PROTON M/Breeze M long fairings, produced by COMS TM. COMS intentional RE due to TM ON under fairing has been assessed considering PROTON M / BREEZE M fairing characteristics. As fairings of all launchers present similar sizes, a similar E-field level under fairing is expected for the other launchers. As a result, the RE level under faring is compliant with COMS RS limits, but is not compliant with RS requirements of the launcher PROTON M/Breeze M.