• 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 KSME Conference
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• 2002.08a
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• pp.439-442
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• 2002

In this study, a turbulence simulation is carried out in a suction type wind tunnel using grids, where turbulent flows with various turbulence intensity are successfully produced by the change of grid size, arrangement of grids and settling position, respectively. Response tests of rectangular cylinder models with aspect ratio of 2 and 4 are carried out in smooth flow and generated turbulent flows. Additionally, two types of fairing are considered such as right triangle and regular triangle. The effects of wind velocity fluctuations and fairing are discussed on vortex-induced oscillation.

• Transactions of the Korean Society of Automotive Engineers
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• v.1 no.3
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• pp.95-108
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• 1993

The needs for smooth curves and surfaces are increasing in modeling cars, ships, airplanes, and other consumer products either for aesthetic or functional purpose. However, the curves and surfaces generated by conventional modeling methods usually exhibit an unwanted behavior due to digitizing errors or inadequate generation method, and thus much time and extra effort is spent afterwards to get the faired results. The objective of this work is to develop a fairing scheme by which well refined shape of a surface can be acquired with detecting and removing the shape imperfections of the given surface represented by NURBS. The fairing scheme is based on an optimization process in which the control points of the given surface are repositioned to minimize the integration of the jumps(perturbations) of the unit normal vectors at all surface points.

• Journal of the Korea Institute of Military Science and Technology
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• v.22 no.4
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• pp.527-535
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• 2019

Hanger in a rail-launched missile protrudes in general and causes to increase significant drag force. One method to avoid the significant increase of drag force is to apply fairings on the hanger. In this paper, sloping shaped fairing parameters of height, width, and length are optimized to minimize the drag force under subsonic speed region by examining three configurations of fairings : front-fairing only, rear-faring only, and the both front and rear fairing. We use Latin Hypercube Sampling method to determine the experimental points, and computational fluid dynamics with incompressible RANS solver was applied to acquire the data at sampling points. Then, we construct a meta model by kriging method. We find the best choice among three configurations examined : both front and rear fairing reduce the drag force by 63 % without the constraint of fairing mass, and front fairing reduced the drag force by 52 % with the constraint of hanger mass.

• 한국전산유체공학회:학술대회논문집
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• 2005.10a
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• pp.269-273
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• 2005

The on-board system for the air supply to the payload fairing(PLF) of a launch vehicle using both high and low pressure air was designed. The design concept was obtained from the CFD analysis of a Russian interstage air supply system, and a collector was adopted to expand the high pressure air. To verify that the on-board system would work as designed, a simplified axisymmetric computational model was made and a CFD analysis was also performed. It was found that the flow ejected from the hole of the collector expands to the Mach number of 4 and is soon retarded due to the action of viscosity. It was also found that a small gap between the low pressure duct and equipment bay wall can cause large velocity in PLF over the velocity requirement and no gap should be allowed in the design.

• The Journal of the Acoustical Society of Korea
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• v.39 no.4
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• pp.342-350
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• 2020

Acoustic and vibration research activities for the structural development of Korean space launch vehicles are introduced in this paper. Various dynamic loads exerted on a launch vehicle during its operation are summarized. The acoustical design method of payload fairings which protect satellites from harsh launch environment was reviewed. Several acoustic research activities were performed to enhance the analytical prediction ability during the development period of the Naro and the Nuri launcher. Specifically, the following research activities are reviewed: a test and vibro-acoustic analysis of composite cylinders whose layup properties are varied, a research on low-frequency acoustic load reduction by an acoustic resonator array and an acoustic test on the cylinder part of the Naro payload fairing. A vibro-acoustic analysis result for the Nuri launcher was introduced and predicted acoustic and vibration levels and measured ones are shown to be in a good agreement.

• Journal of the Korean Society for Aeronautical & Space Sciences
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• v.38 no.3
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• pp.213-220
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• 2010

This paper presents the analysis results of trajectory, performance and attitude control based on the first flight data of the KSLV-I. The KSLV-I had a fairing separation problem and failed to inject spacecraft into the orbit. In this paper, the trajectory, flight performance, and attitude control was analyzed considering the influence of unseparated fairing. Moreover, the flight results and performance of the inertial navigation and guidance system were presented. As a results of post-flight analysis, any other problem besides the fairing separation problem was not happened and onboard equipment functioned normally.

• Proceedings of the Korean Society for Noise and Vibration Engineering Conference
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• 2005.05a
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• pp.250-253
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• 2005

This paper is investigates the separation shock of payload fairing. Separation test of subscale PLF using half separation device and half PLA is performed. Resulting shock loads at equipment bay and fairing joint are measured. Pyroshock estimation is performed using AUTOSEA Pyroshock Module. Input data to analysis model is obtained from the separation test results of subscale PLF. And model of AUTOSEA is updated comparing results between tests and analysis.. This enables us to validate the AUTOSEA model. Tuned model of subscale PLF and separation device is used to update full scale model, and the shock analysis result of full scale model is estimated in this paper. This paper also discusses the results regarding the difficulty of structural modeling and its numerical implementation in AutoSEA2 Software.

• Journal of Aerospace System Engineering
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• v.12 no.3
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• pp.38-44
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• 2018

Military aircraft may have fatigue cracks in structurally weak areas due to multiple factors such as the accumulation of flight time while perform various missions and unpredictable air conditions. As a fatigue crack progresses, there is a risk that the structure will be destroyed in extreme cases, which can have a significant impact on flight safety. In this study, a cracking phenomenon was observed during the periodic inspection the inner support of the fairing, which is installed to protect the connection between the wing and the body of the aircraft. Therefore, a study on a series of quality improvement processes for reformation was described. In order to identify the causes of cracks, pre-load generation occurrence during the wing assembly process was investigated and a fracture analysis was performed. Also, the design of the support structure was suggested in terms of preventing recurrence of cracks. The structural integrity was verified using a stress and fatigue life analysis.

• 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