• 한국가시화정보학회:학술대회논문집
• /
• 2004.04a
• /
• pp.9-18
• /
• 2004

초음속 유동하에서 측추력기 주위의 유동 현상을 실험 및 수치해석을 이용하여 해석하였다. 실험은 버지니아공대의 초음속 풍동과 건국대의 초음속 풍동을 사용하였으며 계산 코드는 Aerosoft 사의 GASP(ver.4.0)과 건국대의 AADL3D를 사용하였다. 실험결과는 Schlieren, Shadow graph 등의 가시화 장치와 압력 센서와 PSP(Pressure Sensitive Paint)를 이용하여 유동장 특성과 압력분포를 구하여 실제 작용되는 힘과 모멘트를 구하였다. 실험조건은 자유류의 흐름이 마하수 4 이고 측추력기와 자유류의 압력비가 532 이었다. 성능향상 방안으로 측추력기 후방에 램프를 설치하는 것을 제안하였으며 이에 대한 실험을 수행하여 수직력에 대한 변화는 없지만 피칭다운 모멘트가 약 $70\%$ 감소함을 보여주어 실제로 성능이 향상되었음을 입증하였다. 또한 측추력기의 성능에 영향을 주는 여러 가지 인자들에 대한 가시화실험을 수행하여 그 이해를 돕고자 하였으며, 현재 건국대에서 보유하고 있는 고속유동 관련 실험장치의 소개와 이를 이용한 연구들을 소개하므로써 압축성 유동장 연구에 이러한 실험장치의 필요성에 대한 이해를 구하고자 한다.

• Journal of the Korean Society for Aeronautical & Space Sciences
• /
• v.40 no.11
• /
• pp.927-933
• /
• 2012

The characteristics of two-dimensional supersonic coanda flow was experimentally investigated. For various ratios of slot height to coanda wall's radius of curvature, surface roughnesses, and jet stagnation pressures, the characteristics of the supersonic coanda flow such as shock structures and hysteresis were observed by flow visualization. It was found that the characteristics of hysteresis of the coanda jet was related to the surface roughness of the coanda wall. The study was further extended for application of the tangentially injected coanda jet to control co-flowing highly compressible main jet direction. It was noticed that the stagnation pressure of the main jet as well as the ratio of the slot height to coanda wall's radius of curvature wall was an influencing factor in the performance of the fluidic thrust vectoring method.

• Journal of the Korean Society for Aeronautical & Space Sciences
• /
• v.42 no.9
• /
• pp.723-730
• /
• 2014

Experimental study for supersonic co-flowing fluidic thrust vectoring control utilizing the secondary flow is performed. The characteristics of the thrust vectoring of two dimensional supersonic flow (Mach 2.0) are studied by Schlieren flow visualization and highly-accurate multi-component force measurements using the load cells. It is observed that the thrust deflection angle initially decreases and increases again forming a V-shaped variation as the pressure of the secondary flow increases. Characteristics of the performance coefficients of the system are also studied, and the detailed operating conditions for higher performance of the technique are suggested.

• Journal of Aerospace System Engineering
• /
• v.13 no.6
• /
• pp.9-16
• /
• 2019

The experiment on the liquid jet in crossflow in supersonic BFS (backward-facing step) flow was conducted to investigate the mixing characteristics. The working fluids are nitrogen and water. The shadow graph technique was used to visualize the flow field. Images captured by the high-speed camera were applied to analyze the flow phenomena. The liquid jet was injected at the re-circulation zone created by the supersonic jet flow. Experimental conditions are defined based on the pressure of the nitrogen gas chamber and pressurized liquid tank. In respective cases, the penetration depth of liquid jet and location of the Mach disc were observed to be proportional to the momentum ratio of gas and liquid jets.

• Journal of the Korean Society of Propulsion Engineers
• /
• v.22 no.3
• /
• pp.53-64
• /
• 2018

In this study, computational simulation was performed to investigate the characteristics of air/fuel mixing according to the shape of the injector exit when the transverse jet was injected into a supersonic flow. Non-reacting flow simulation was conducted with fixed mass flow rate and the same cross-sectional area. To validate the results, free stream Mach number and jet-to-crossflow memetum ratio are set to 3.38 and 1.4, respectively, which is same as the experimental condition. Further, separation region, structure of the under-expended jet, jet penetration height, and flammable region of hydrogen for five different injectors compared.

• Journal of the Korean Society for Aeronautical & Space Sciences
• /
• v.32 no.4
• /
• pp.73-79
• /
• 2004

An experimental and computational study has been performed for investigation of the jet interaction in supersonic flow with a ramp located behind a sonic, lateral jet. The experimental techniques include schlieren, pressure taps, and Pressure Sensitive Paint. The numerical solver used in this study is AeroSoft's structured flow solver GASP Version 4.0. A Mach 4 crossflow with a pressure ratio of 532, and the 3D ramp was designed by parametric study using GASP. The results showed that the ramp located downstream of the jet decrese the nose-down pitching moment by 70% without a force loss.

• Proceedings of the Korean Society of Propulsion Engineers Conference
• /
• 2010.05a
• /
• pp.353-356
• /
• 2010

A computational study on the enhancement of parallel supersonic-subsonic mixing wakes is conducted and compared with available experimental data. The first aim of the present work is to show a direct comparison between numerical predictions and equivalent experimental data for the baseline case. The Pitot pressure distribution data are in good agreement between computation and experiment, and the results show that Menter's SST model with the compressibility correction gives the best performance. Further we investigate the effects of primary parameters such as the position of the cavity, and the arrangement of the cavity at the given flow condition.

• Transactions of the Korean Society of Mechanical Engineers B
• /
• v.26 no.6
• /
• pp.765-771
• /
• 2002

This Paper presents numerical solutions of two-dimensional Euler equations for supersonic steady and unsteady flows with heat addition in a convergent-divergent duct, The Van Leer FVS (flux vector splitting) method in generalized coordinates is employed in order to calculate the inviscid strong shock waves caused by thermal choking. We discuss on transient characteristics, start and unstart phenomena caused by thermal choking, limit of equivalence ratio to avoid thermal choking and fluctuation of specific thrust caused by thermal choking. We prove that thermal choking is a serious problem in view of engine performance.

• 한국전산유체공학회:학술대회논문집
• /
• 2010.05a
• /
• pp.21-27
• /
• 2010

The flow characteristics on a supersonic inlet with bleeding system by changing angles of attack and channel length conditions are studied by computational 3D turbulent flow analysis. A compressible upwind flux difference splitting Navier-Stokes method with $k-{\omega}$ turbulence model is used to analysis the inlet flowfield. More non-uniform flowfields are shown at the AIP when angle of attack becomes bigger and bigger. These non-uniform flowfield works the performance aggravating factors of the supersonic engine. Non-uniform flowfield by changing channel length at the various angle of attack are investigated.

• Proceedings of the Korean Society of Propulsion Engineers Conference
• /
• 1997.11a
• /
• pp.4-4
• /
• 1997

로켓 조종장치는 크게 추력방향 조종(TVC, Thrust Vector Control) 장치, 측면추력조종(Lateral Thrust Control) 장치 그리고 공기역학 조종면으로 분류할 수 있다. 조종장치의 공통된 특징은 모터가 작동하거나 유도탄이 비행할 때만 타의 효과가 발생한다는 점이다. 그러므로 조종장치를 개발하기 위해서는 이상류 초음속 유동이나 삼음속 이상의 자유유동(freestream)을 지상에서 효과적으로 모의할 수 있는 지상 시험장치가 필요하다. 이 시험장치에는 초음속 풍동과 유동 시험장치(cold-flow test stand), 그리고 6분력 트러스트 스텐드가 포함된다. 삼성항공은 우주용 추진기관의 성능을 지상에서 간단한 장치를 구현하여 시험할 수 있는 모의연소 시험장치, 노즐유동에 포함된 고체입자를 직접 수집할 수 있는 고체입자 포집장치 등 각종 시험장치를 제작하였다. 이를 바탕으로 차세대 전술유도탄의 핵심기술가운데 하나인 조종장치와 이를 효과적으로 개발하기 위한 지상 시험장치 확보에 착수하고 있다.