• 한국분무공학회지
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• 제12권2호
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• pp.115-122
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• 2007

The spray characteristics and drop size measurements have been experimentally studied in liquid jets injected into subsonic crossflow. With water as fuel injection velocity, injection angle and atomize. internal flows were varied to provide of jet operation conditions. The injector internal flow was classified as three modes such as a non-cavitation flow, cavitation, and hydraulic flip flows. Pulsed Shadowgraph Photography measurement was used to determine the spatial distribution of the spray droplet diameter in a subsonic crossflow of air. And this study also obtains the SMD (Sauter Mean Diameters) distribution by using Planar Liquid Laser Induced Fluorescence technique. The objectives of this research are get a droplet distributions and drop size measurements of each condition and compare with the other flow effects. As the result, This research has been showned that droplet size were spatially dependent on air-stream velocity, fuel injection velocity, injection angle effects, and normalized distance from the injector exit length(x/d, y/d). There are also different droplet size characteristics between cavitation, hydraulic flip and the non-cavitation flows.

• 한국추진공학회:학술대회논문집
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• 한국추진공학회 2010년도 제34회 춘계학술대회논문집
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• pp.353-356
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• 2010

평행 초음속-아음속 후류유동에서 혼합증대에 관한 수치적인 연구를 실험결과와의 비교를 통하여 수행하였다. 이번 연구의 첫 번째 목적은 실험에서 사용된 조건으로 정확하게 수치적으로 모사하는데 있다. Pitot 압력을 이용하여 수치계산결과와 실험치와 비교하였을 때 서로 일치된 결과를 얻었으며, 그 중에서 압축성 수정을 가미한 $k-{\omega}$ SST 난류모델의 계산결과가 가장 좋은 것으로 나타났다. 게다가 기존의 유동조건에서 공동의 위치, 배열수에 변화를 주면서 혼합특성을 비교/연구하였다.

• 대한기계학회논문집
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• 제12권6호
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• pp.1407-1414
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• 1988

본 연구에서는 저자들에 의해 이미 개발된 경계유선수정법에 의한 B-B 유동계 산을 통해 익열의 편차각을 계산하고 기존의 예측방법에 의한 결과와 비교 검토하여 압축성 및 3차원 비축대칭성의 효과를 검토하였다.

• EDISON SW 활용 경진대회 논문집
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• 제5회(2016년)
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• pp.647-652
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• 2016

To reduce drag force at supersonic speeds, sharp leading edge is hugely efficient. It is, however, incompatible with leading edge shape to have fine aerodynamic characteristics at subsonic and transonic speeds. It is critical to reduce drag force for enhanced cruise performance and higher efficiency. An air superiority fighter, however, required to have high maneuverability for survivability, and sharp leading edge is not proper. Consequently, variable leading edge is demanded to reduce drag force significantly at supersonic speeds for cruise performance. Leading edge altering system is constructed with rigid material to improve possibility of realization, and minimized movement of its components in altering for reduce effects on flight. It is compared with bi-convex airfoil and NACA 65-006 airfoil, which have comparable maximum thickness. At Mach number 1.7 and zero angle of attack, supersonic mode of designed airfoil indicates approximately 17% higher drag coefficient than the bi-convex airfoil indicates, it is, however, 23% lower than the NACA 65-006 indicates. Also, subsonic mode of the designed airfoil shows fine aerodynamic characteristics in comparison with NACA 65-006 airfoil in subsonic and transonic speed range. In this regard, design of the airfoil achieved the object of this study satisfactorily.

• 한국추진공학회:학술대회논문집
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• 한국추진공학회 2008년 영문 학술대회
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• pp.612-621
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• 2008

For the purpose of improving accuracy in jet noise prediction and investigating its generation mechanism, high subsonic jets were computed by using compressible Large Eddy Simulation(LES), wherein the inflow forcing or disturbance added in the inflow shear layer was incorporated. The far-field Sound Pressure Levels(SPL) as well as the flow field resulted in good agreement with available experimental data by applying only the high azimuthal modes among the inflow forcing parameters. We found that this result was due to an important role of the inflow forcing upon breaking down the axiymmetric vortices that caused high amplitude velocity and pressure fluctuations. In order to examine generation mechanism of the dominant noise component, wavelet transformation was introduced to reveal the presence of a well-organized structure of pressure fluctuations that originated mainly from vortex motions near the end of the jet potential core. This structure took a train of alternately positive and negative wavelet-transformed pressure regions along the jet distance, spreading towards the downstream with advection and propagation. It was concluded that this structure and its dynamic motion are the reason why a high subsonic jet produces the dominant noise with a particular downstream directivity.

• 한국추진공학회:학술대회논문집
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• 한국추진공학회 2008년 영문 학술대회
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• pp.486-491
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• 2008

The spray characteristics and drop size measurements have been experimentally studied in liquid jets injected into subsonic crossflow. With water as fuel injection velocity, injection angle and atomizer internal flows were varied to provide of jet operation conditions. The injector internal flow was classified as three modes such as a non-cavitation flow, cavitation, and hydraulic flip flows. Pulsed Shadowgraph Photography measurement was used to determine the spatial distribution of the spray droplet diameter in a subsonic crossflow of air. And this study also obtains the SMD(Sauter Mean Diameters) distribution by using PLLIF(Planar Liquid Laser Induced Fluorescence) technique. The objectives of this research are getting a droplet distribution and drop size measurement of each condition and compare with the other flows effect. As the result, This research have been showed the droplet size were spatially dependent on air-stream velocity, fuel injection velocity, injection angle effects and normalized distance from the injector exit length.(x/d, y/d)There are also different droplet size characteristics between cavitation, hydraulic flip and the non-cavitation flows.

• 한국추진공학회지
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• 제25권3호
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• pp.81-88
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• 2021

아음속 순항 유도탄의 추진시스템은 소형 가스터빈 엔진을 중심으로 공기흡입관, 탄내 연료이송계통 등으로 구성된다. 이는 엔진의 수락시험으로부터 시작하여, 엔진의 여러 기능 및 보기류의 설계수정, 엔진과 연동되는 각종 탄내 장비들의 설계/개발 및 상호 인터페이스 확인을 위한 해석과 통합시험 등으로 완성된다. 여기서는 이와 같은 소형 가스터빈 엔진을 이용한 유도탄 추진시스템 체계통합기술의 구성과 각 단계별 요소기술의 개요를 서술한다.

• 한국항공우주학회지
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• 제50권6호
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• pp.367-376
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• 2022

본 연구에서는 정상 및 비정상 공력 해석이 가능한 3차원 아음속 비정렬 패널 프로그램을 개발하고 검증하였다. 물체의 표면을 삼각형 또는 사각형 패널에 source와 doublet의 potential을 분포하여 모델링하였다. 따라서 복잡한 형상과 다물체도 쉽게 모델링 할 수 있다. Kelvin theory와 비정상 Kutta condition을 이용하여 비정상 유동에서 wake의 doublet 크기를 결정하였다. 2차원 및 3차원에서 정상 및 비정상 유동을 해석하여 그 결과를 해석해와 기존의 수치해와 비교하였다.

• 한국항공운항학회:학술대회논문집
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• 한국항공운항학회 2006년도 춘계학술대회 논문집
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• pp.85-89
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• 2006

• 한국항공운항학회:학술대회논문집
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• 한국항공운항학회 2005년도 추계학술발표대회 논문집
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• pp.164-167
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• 2005