• Journal of the Korean Society for Aeronautical & Space Sciences
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• v.39 no.12
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• pp.1141-1149
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• 2011

In order to enhance the aircraft survivability, infrared signatures emitted by engine parts should be diminished. For its reduction it is necessary for the rear fuselage temperature to be decreased. In this study, numerical modeling of flow fields and heat transfer of nozzle is performed and its temperature distribution along each component wall is predicted. The effects of material characteristics and shape of nozzle wall and radiation shield on the heat transfer are also investigated. Through this numerical analysis, design parameters related to the susceptibility of aircraft are examined.

• Proceedings of the Korean Society of Propulsion Engineers Conference
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• 2007.04a
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• pp.358-361
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• 2007

Most aircraft cruise in the stratosphere at which temperature is below $-50^{\circ}C$ md, as a result, the surface of aircraft can be iced up. Ice on the wing can change aerodynamic characteristic and results in the deterioration of its performance. Ice on the engine inlet increases the possibility of compressor blade damage and affects the performance and safety of the engine. This paper focused on the development of icing simulation device for analyzing effect of icing on engine performance. Icing simulation tests were conducted with a liquid air system and a icing simulation device and results show that icing could be simulated with this system.

• Journal of the Korean Society of Propulsion Engineers
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• v.5 no.3
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• pp.19-24
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• 2001

The Pilot-Tube is the device that measures velocity and altitude of high speed vehicle. Accurate measurements of speed and altitude are essential to the safe and efficient operation of aircraft. For the purpose of determining optimal design parameters of Pilot-Tube such as nose inlet configuration, nose shape, static hole configuration, and static hole location, subsonic flow field was calculated numerically and analyzed. A Pilot-Tube was manufactured based on numerical flow field analysis, and pressure and air velocity was measured experimentally in the wind tunnel. As a result manufacturing and design technologies of the Pilot-Tube were acquired to make flight-device.

• Journal of the Korean Society for Aeronautical & Space Sciences
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• v.47 no.5
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• pp.319-325
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• 2019

The main purpose of this study is to compare the bird strike analysis result of the radome composed of composite laminate and sandwich structure attached to aircraft with test result. First of all, we generated bird model which has water properties through SPH(Smoothed Particle Hydrodynamics) method. And then bird strike analysis was conducted with initial velocity of bird measured from bird strike test. From analysis result we investigated whether structural failure occurred or not onto the radome and compare maximum displacement of the radome structure with test result. Also reliability of numerical analysis model was confirmed through time-dependent pressure trend on this collision process matched existing research result. Furthermore, we confirmed that failure behavior of the radome can be affected by density of the particles in the bird model.

• Journal of the Korean Society for Aeronautical & Space Sciences
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• v.48 no.5
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• pp.335-342
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• 2020

Tailless aircraft designed for stealth efficiency uses spoilers instead of rudders for the directional control. When the spoiler is rapidly deployed, highly nonlinear and unsteady aerodynamic characteristics can be generated, resulting in adverse effects on aircraft flight performance. This paper investigates the aerodynamic characteristics of an airfoil with moving spoiler using dynamic mesh CFD technique. The effects of spoiler operation speed, mounting location, and deployment scheduling are analyzed to reduce the adverse effects of the spoiler's dynamic operation. The results shows that the adverse effects of dynamic spoiler can be reduced by appropriate selection of the spoiler mounting location and deployment scheduling.

• Journal of the Korean Society for Aeronautical & Space Sciences
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• v.45 no.11
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• pp.951-966
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• 2017

In this work, numerical analyses are carried out and the behaviors are investigated for three types of double-acting oleo-pneumatic shock absorbers along with the mathematical models proposed in the part I of this work. After presenting each numerical algorithm corresponding to each model, the numerical algorithms are implemented as user-subroutines in MSC/ADAMS commercial multi-body dynamic software. By using the developed user-subroutines, numerical studies are carried out for compression/stretch test as well as drop test. From the comparative studies, we investigated the salient feature of each double-acting oleo-pneumatic shock absorber. Results identifies that it is possible to increase the absorbing efficiency in accordance with the requirements for aircraft landing conditions.

• The Journal of Korean Institute of Electromagnetic Engineering and Science
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• v.27 no.8
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• pp.766-773
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• 2016

This paper proposes an aircraft-installed compact offset-parabolic-reflector antenna for the spinning direction-finding applications. The feeder of the reflector antenna is a LPDA antenna that has the ultra-wideband characteristics and the $45^{\circ}$ slant linear polarization. The reflector is designed to be slanted by $5^{\circ}$ in the elevation and to be small in size on the basis of the reference parabolic shape for the purpose of the high gain and mounting on the underside of aircraft fuselage. Over the ultra-wideband 20:1 bandwidth from S to Ka band, the measured average gain of the proposed antenna is 27.97 dBi, and the average half-power beam width is $4.55^{\circ}$ in the azimuth and $4.3^{\circ}$ in the elevation which is the pencil-beam radiation pattern. All the measured data are similar to the simulation results. The designed compact offset-parabolic-reflector antenna that is installed in the limited area has the ultra-wideband and high-gain characteristics. We expect that the newly designed antenna can be applied to the spinning direction-finding antenna system installed in an aircraft.

• Aerospace Engineering and Technology
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• v.7 no.1
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• pp.24-29
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• 2008

Aircraft fuel efficiency is one of main concerns to aircraft manufacturers and to aviation companies because jet fuel price has tripled in last ten years. One of simple and effective methods to increase fuel efficiency is to reduce aircraft induced drag by using of wingtip devices. Induced drag is closely related to the circulation distribution, which produces strong wingtip vortex behind the tip of a finite wing. Wingtip devices including winglets can be successfully applied to reduce induced drag by wingtip vortex mitigation. Winglet design, however, is very complicated process and has to consider many parameters including installation position, height, taper ratio, sweepback, airfoil, toe-out angle and cant angle of winglets. In current research, different shapes of winglets are compared in the view of vortex mitigation. Appropriately designed winglets are proved to mitigate wingtip vortex and to increase lift to drag ratio. Also, the results show that winglets are more efficient than wingtip extension. That is the reason B-747-400 and B-737-800 chose winglets instead of a span increase to increase payload and range. Drag polar comparison chart is presented to show that minimum drag is increased by viscous drag of winglet, but at high lift, total drag is reduced by induced drag decrease. So, winglets are more efficient for aircraft that cruises at a high lift condition, which generates very strong wingtip vortex.

• Journal of the Korea Academia-Industrial cooperation Society
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• v.20 no.8
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• pp.181-189
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• 2019

An aircraft power distribution device distributes and controls the power generated by the generator and provides overcurrent protection. There are many defect phenomena that make AC power distribution impossible during flight, which poses a problem in because some electronic equipment cannot be operated. We describe a process of deriving the root cause of defects by using vibration testing equipment to simulate the vibration conditions during aircraft flight, which result in defects. The results show that the cause of the defect is internal wiring damage caused by the vibration of the contactor of the AC power distribution device. Therefore, the shape of the contactor was improved to solve this problem. We also improved the test procedure by performing defect detection tests using vibration testing equipment to detect a faulty contactor. As a result of the improvements, a component certification test and flight test proved that the defect phenomena of the AC electrical master box were improved.

• Journal of the Computational Structural Engineering Institute of Korea
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• v.25 no.1
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• pp.51-56
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• 2012

Crashworthy fuel cells have been widely implemented to rotorcraft and rendered a great contribution for improving the survivability of crews and passengers. Since the embryonic stage of military rotorcraft history began, the US army has developed and practised a detailed military specification documenting the unique crashworthiness requirements for rotorcraft fuel cells to prevent most fatality due to post-crash fire. Foreign manufacturers have followed their long term experience to develop their fuel cells, and have reflected the results of crash impact tests on the trial-and-error based design and manufacturing procedures. Since the crash impact test itself takes a long-term preparation efforts together with costly fuel cell specimens, a series of numerical simulations of the crash impact test with digital mock-ups is necessary even at the early design stage to minimize the possibility of trial-and-error with full-scale fuel cells. In the present study a number of numerical simulations on fuel cell crash impact tests are performed with a crash simulation software, Autodyn. The resulting equivalent stresses are further analysed to evaluate a number of appropriate design parameters and the artificial neural network and simulated annealing method are simultaneously implemented to optimize the crashworthy performance of fuel cells.