• 한국전산유체공학회지
• /
• 제19권4호
• /
• pp.68-74
• /
• 2014

This computational study features the transient compressible and inviscid flow analysis on a metallic plasma discharge from the opposing composite electrodes which is subjected to pulsed electric power. The computations have been performed using the flux corrected transport algorithm on the axisymmetric two-dimensional domain of electrode gap and outer space along with the calculation of plasma compositions and thermophysical properties such as plasma electrical conductivity. The mass ablation from aluminum electrode surfaces are modeled with radiative flux from plasma column experiencing intense Joule heating. The computational results shows the highly ionized and highly under-expanded supersonic plasma discharge with strong shock structure of Mach disk and blast wave propagation, which is very similar to muzzle blast or axial plasma jet flows. Also, the geometrical effects of composite electrodes are investigated to compare the amount of mass ablation and penetration depth of plasma discharge.

• 대한기계학회:학술대회논문집
• /
• 대한기계학회 2004년도 추계학술대회
• /
• pp.625-630
• /
• 2004

An advanced method of Relaxed Static Stability (RSS) is utilized for improving the aerodynamic performance of modern version supersonic jet fighter aircraft. The laws of flight control system utilize RSS criteria in both longitudinal and lateral-directional axes to achieve performance enhancements. Particularly, the design of longitudinal control laws for utilizing RSS methods greatly affects the performance of the aircraft in Air-to-Air Tracking and Air-to-Ground modes, which improves weapon delivery. In the area of Airto- Air Tracking, the development of longitudinal control laws aids in the fine tracking and gross acquisition of other aircraft. This paper proposes that Air-to-Air fine tracking can be improved via RSS control law design methods without effecting Air-to-Air gross acquisition.

• 한국항공운항학회지
• /
• 제26권2호
• /
• pp.76-82
• /
• 2018

A test simulator is needed to develop a fuel quantity measurement system that takes into account the roll and pitch motion of the aircraft. In this paper, we develop a test simulator that consists of attitude simulation equipment, fueling equipment, and data storage equipment. The attitude simulation equipment simulates the aircraft attitude. It is manufactured to operate pitch angle and roll angle movement. The fueling equipment supplies fuel to the supplementary fuel tank. The data storage equipment collects and stores the measured data. We also develop an automation software that operates the test simulator and collects data automatically. The test simulator has been automated to prevent testers from being exposed to toxic fuel. Through automation software, the collection period is reduced by one quarter compared to manual collection. The developed fuel quantity measurement system is verified through the test simulator.

• 한국추진공학회:학술대회논문집
• /
• 한국추진공학회 1998년도 제11회 학술강연회논문집
• /
• pp.34-34
• /
• 1998

차세대 비행체가 갖추어야 할 요건으로 다양한 작동 범위에서 다목적으로 사용될 수 있어야 한다는 점이다. 비행체는 작전시 초음속으로 순항해야 하며, 폭탄으로 손상된 비행장에서도 이륙하여 작동할 수 있도록 짧은 이륙과 착륙 거리를 가져야 하기 때문에 현재 비행체보다 더 큰 받음각에서 작동하여 비행시 뛰어난 기동성을 가져야 한다. 제어력을 향상시키기 위해서 받음각과 동압에 의존하지 않고 큰 제어 모멘트를 제공하는 차세대 방법은 엔진의 배기가스를 원하는 비행 방향으로 제어하는 것으로 이러한 방법을 추력 편향 제어(Thrust Vector Control)라고 한다. 기존 공력에 의한 비행 자세제어 방법은 속도의 2승에 비례하는 제어력을 발생하지만, 실속을 피해야하기 때문에 공기력을 이용한 날개 및 비행체의 받음각에 한계가 있어 비행체의 선회능력을 제한하며 고공에서 저속비행 하는 경우에는 공기의 밀도가 낮고 동압이 작게 작용하여 선회능력은 낮아진다. 그러나, 추력 편향 장치는 공력을 이용하지 않고 추력을 이용하기 때문에 실속에 의한 제한이 없어 큰 받음각(70$^{\circ}$-90$^{\circ}$)으로 선회할 수 있어 월등한 기동성을 발휘할 수 있다. 이러한 추력 편향 장치 중 제트 베인형은 소형화가 가능하고, 하나의 노즐로 수직, 수형 및 횡 방향의 3축 제어를 할 수 있어 많이 사용되고 있다.

• 한국소성가공학회:학술대회논문집
• /
• 한국소성가공학회 2006년도 춘계학술대회 논문집
• /
• pp.145-148
• /
• 2006

Cold gas dynamic spray is a relatively new coating process by which coatings can be produced without significant heating during the process. Cold gas dynamic spray is conducted by powder sprayed by supersonic gas jet, and generally called the kinetic spray or cold-spray. Cold-spray was developed in Russia in the early 1980s to overcome the defect of thermal spray method. Its low process temperature can minimize thermal stress and also reduce the deformation of the substrate. Most researches on cold-spray have focused on micro scale coating, but our research team tried to apply this method to macro scale deposition. The macro scale deposition causes deformation of a thin substrate which is usually convex to the deposited side. In this research, the main cause of the deformation was investigated using 6061-T6 aluminum alloy and properties of deposited aluminum layer such as coefficient of thermal expansion, Elastic modulus, hardness, electric conductivity were measured. From the result of the analysis, it was concluded that compressive residual stress was the main reason of substrate deformation while CTE had little effect.

• 한국유체기계학회 논문집
• /
• 제18권5호
• /
• pp.49-53
• /
• 2015

Thrust vector control is the method which generates the side force and roll moment by controlling exhausted gas directly in a rocket nozzle. TVC is classified by mechanical and fluid dynamic methods. Mechanical methods can change the flow direction by several objects installed in a rocket nozzle exhaust such as tapered ramp tabs and jet vane. Fluid dynamic methods control the flight direction with the injection of secondary gaseous flows into the rocket nozzle. The tapered ramp tabs of mechanical methods are used in this paper. They installed at the rear in the rocket nozzle could be freely moved along axial and radial direction on the mounting ring to provide the mass flow rate which is injected from the rocket nozzle. TVC of the tapered ramp tabs has the potential to produce both large axial thrust and high lateral force. We have conducted the experimental research and flow analysis of ramp tabs to show the performance and the structural integrity of the TVC. The experiments are carried out with the supersonic cold flow system and the schlieren graph. This paper provides to analyze the location of normal shock wave and distribution of surface pressure on the region enclosed by the tapered ramp tabs.

• 제어로봇시스템학회논문지
• /
• 제12권7호
• /
• pp.713-718
• /
• 2006

Supersonic jet fighter aircraft have several different weapon loading configuration to support air-to-air combat and air-to-ground delivery of weapon modes. Especially, asymmetric loading configurations could result in decreased handling qualities for the pilot maneuvering of the aircraft. The design of the T-50 lateral-directional roll axis control laws change from beta-betadot feedback structure to simple roll rate feedback structure and gains such as F-16 in order to improve roll-off phenomena during pitch maneuver in asymmetric loading configuration. Consequently, it is found that the improved control law decreases the roll-off phenomenon in lateral axes during pitch maneuver, but initial roll response is very fast and wing pitching moment is increased. In this paper, we propose the lateral control law blending between beta-betadot and simple roll rate feedback system in order to decreases the roll-off phenomenon in lateral axes during pitch maneuver without degrading of roll performance.

• 한국항공우주학회지
• /
• 제42권6호
• /
• pp.488-494
• /
• 2014

유도탄 발사 시 화염은 발사 장치 및 인접 구조물에 심각한 손상을 야기할 수 있다. 본 연구는 유도탄 발사 시 함정과 유도탄의 초기 운동에 의해 유도탄의 화염이 인접 구조물에 미치는 영향을 분석하기 위하여 수행하였다. 이를 위해 함정과 유도탄의 초기 운동에 영향을 미치는 각 인자들을 확률분포로 정의하고 Monte Carlo 해석 기법을 이용하여 통계적으로 발생할 수 있는 유도탄 이탈 영역을 분석하였다. 그 후 유도탄의 화염이 인접 구조물에 가장 큰 영향을 미치는 유도탄 이탈 궤적에 대해 CFD기법을 이용하여 유동-운동해석을 수행하였다. 이와 같은 방법으로 유도탄 발사 시 함정과 유도탄의 초기 운동에 의해 유도탄 화염이 인접 구조물에 미치는 영향을 분석하였다.

• 한국항공우주학회지
• /
• 제34권4호
• /
• pp.1-10
• /
• 2006

비정상 공기역학적 해석코드와 동역학적 해석 프로그램이 연계된 코드를 이용하여 단분리 시스템의 유동해석과 함께 분리과정의 거동을 해석하였다. 본 연구는 일단 추진 모터를 가진 장거리 미사일 단분리과정 만을 연구대상으로 하였다. 연구의 목적은 이러한 단분리 시스템의 안전성과 신뢰도를 검증하기 위해 단분리 과정에 대한 비정상 동역학 시뮬레이션을 수행하였다. 특히 비행 중 받음각 요란에 의한 자유흐름 조건의 변화에 대해서도 시뮬레이션을 수행하여, 받음각 요란이 단분리의 안정성과 신뢰도에 미치는 영향을 알아보고자 하였다. 해석코드는 병렬화 된 중첩 정열격자계를 사용하여 비정상 초음속 오일러 코드로 공기역학적 해석을 한 후, 이 결과를 6자유도를 갖는 운동방정식의 입력 데이터로 하여 동역학적 시물레이션을 수행하였다.

• 제어로봇시스템학회논문지
• /
• 제12권11호
• /
• pp.1130-1137
• /
• 2006

Relaxed Static Stability(RSS) concept has been applied to improve aerodynamic performance of modern version supersonic jet fighter aircraft. Therefore, the flight control systems are necessary to stabilizes the unstable aircraft and provides adequate handling qualities. The initial production flight control system are verified by flight test and it's always an elements of danger because of flight-critical nature of control law function and design error due to model base design method. These critical issues impact to flight safety, and it could be lead to a loss of aircraft and pilot's life. Therefore, development of an easily modifiable RFCS(Research Flight Control System) capable of reverting to a PFCS(Primary Flight Control System) of reliable control law must be developed to guarantee the flight safety. This paper addresses the concept of SSWM(Software Switching Mechanism) using the fader logic such as TFS(Transient Free Switch) based on T-50 flight control law. The result of the analysis based on non-real time simulation in-house software using SSWM reveals that the flight control system are switching between two computers without any problem.