http://chineseinput.net/에서 pinyin(병음)방식으로 중국어를 변환할 수 있습니다.
변환된 중국어를 복사하여 사용하시면 됩니다.
VALIDATION OF NUMERICAL APPROACH FOR THE SEDIMENT OF MULTI-SIZE PARTICLES IN A FLUID CONTAINER
지영무,최상민 한국전산유체공학회 2013 한국전산유체공학회지 Vol.18 No.2
In this paper, we reported the verification of numerical simulation approach for sedimentation of the multi-size particles in a container. The comparison between experimentally measured values and numerically evaluated values on settle down process of fully mixed mixture is carried out. In an attempt to represent the natural particle size distribution, various diameters of single particles are simulated and the results are compared with the outcome of the multi-size computation. When the empirical formula for mean particle size estimation is adopted to define the sediment diameter, computation and comparison are conducted.
일방향 수평가진하는 사각용기에서 발생하는 슬로싱 유동패턴
지영무,박준상 한국유체기계학회 2019 한국유체기계학회 논문집 Vol.22 No.2
In this study, a three-dimensional sloshing problem in a rigid rectangular box with a free surface is considered. The flow is generated by the harmonic motion in time along the horizontal axis, i.e., the oscillation velocity sin, where denotes the amplitude of the oscillation velocity and denotes the frequency of oscillation. Full-matrix experiments were conducted over an externally forced frequency-displacement regime of ≤ ≤ and ≤ ≤ , where denotes the system natural frequency. Examining all possible solutions of the experiment for the parametric regime, we determined that the free surface wave motion can be divided into four representative types : (I) 2-D mild wave, (II) 2-D strongly nonlinear wave, (III) 3-D wave with regular cross-wave structure along the z-direction, and (IV) a chaotic wave. Herein, we present a comprehensive discussion of the characteristics of each wave mode from (I) to (IV).
지영무(Young Moo Ji),신영섭(Young Seop Shin),박준상(Jun Sang Park),현재민(Jae Min Hyun) 대한기계학회 2011 大韓機械學會論文集B Vol.35 No.6
본 연구에서는 사각용기 내에서의 자유표면을 갖는 2차원 슬로싱 문제에 대하여 고찰하였다. 용기 내부의 유동은 수평방향의 조화운동을 통해 형성되며, 외부 가진 속도는 u=Asin(2πft)으로 정의 된다. 여기서 u, A 그리고 f는 외부로부터 작용하는 가진 속도, 변위 그리고 주파수를 각각 나타낸다. 큰 변위(A~O) 슬로싱 문제의 해석을 위한 실험설비를 구축하였으며, 광범위한 영역에서의 PIV실험을 수행하였다. 실험을 통해 자유표면의 움직임(motion)을 각각 서로 다른 물리적 특성을 갖는 세 가지; 선형 슬로싱의 자유표면의 움직임과 유사한 standing wave motion, 사각용기의 속도가 0을 지나는 순간(the moment of turn-over) 측벽에서 발생하는 run-up motion 그리고 측벽으로부터 내부유체로 점차적으로 전파되는 bore motion으로 분류하였다. The two-dimensional sloshing problem in a rigid rectangular tank with a free surface is considered. The flow is generated by a container in harmonic motion in time along the horizontal axis, i.e., a container excited by u=Asin(2πft) where u denotes the container velocity imposed externally, A is the amplitude of the oscillation velocity, and f is the frequency of oscillation. Experimental apparatus is arranged to investigate the large-amplitude sloshing flows in off-resonant conditions, where the large amplitude means that A~O, and the distance, S, is comparable to the breadth, L, of the container, i.e., L/S~O. Comprehensive particle image velocimetry (PIV) data are obtained, which show that the flow physics of the nonlinear off-resonant sloshing problem can be characterized into three peculiar free surface motions: standing-wave motions similar to those of linear sloshing, a run-up phenomenon along the vertical sidewall at the moment of turn-over of the container, and gradually propagating bore motion from the sidewall to the interior fluid region, like a hydraulic jump.
지영무(Ji Young Moo),정연균(Jung Yeon-Gyun),정세영(Jung Se-Young),김광진(Kim Kwang-Jin),엄상진(Uhm Sang-Jin),박준상(Park Jun Sang) 대한기계학회 2008 대한기계학회 춘추학술대회 Vol.2008 No.11
The flow visualization is conducted in order to investigate an unsteady flight characteristic of a model dragonfly. The flapping wings are analyzed using smoke-wire and high speed camera. The results of this experiment show that three mechanisms and high incidence angle of the wings are responsible for the lift. The leading edge vortex, which is induced by the rapid acceleration of the wing at the beginning of a stroke, causes the lift enhancement. The delayed stall during the stroke and the fast supination and pronation of the wing near the end of each stroke are also responsible for the lift generation.
초음속 공중발사 로켓의 모선분리 현상에 관한 수치적 연구
지영무(Young Moo Ji),김영신(Young Shin Kim),이재우(Jae-Woo Lee),박준상(Jun Sang Park) 한국항공우주학회 2005 韓國航空宇宙學會誌 Vol.33 No.8
본 논문에서는 공중발사로켓의 초음속 모선 분리 현상에 관하여 기술하였다. 정상상태와 비정상상태의 해석을 위하여 3차원 Euler방정식을 수치적으로 계산하였다. 해석결과는 모선과 로켓사이의 충격파 간섭현상을 명확히 보여주고 있으며, 로켓의 분리 단계에 중요한 영향을 미치는 인자들을 해석을 통해 찾아내었다. 결과적으로 본 연구를 통하여 초음속 공중발사로켓의 설계에서의 안전한 모선분리를 위한 가이드라인을 제공하였다. This paper describes a supersonic separation of air-launching rocket from the mother plane. Three dimensional Euler equations were numerically solved to analyze steady/unsteady state fluid flows. The results of simulation clearly demonstrate effect of shock-expansion wave interaction between the rocket and the mother plane. Moreover, important influential factors at separating stage of the rocket were extracted with a comprehensive analysis. Finally, from the consideration of supersonic-separation, a guideline to safety-separation is given to the design of supersonic air-launching rocket.
초음속 공중발사를 위한 전기체-로켓의 비정상 분리 유동특성
지영무(Young Moo Ji),이재우(Jae-Woo Lee),변영환(Yung-Hwan Byun),박준상(Jun Sang Park) 한국항공우주학회 2007 韓國航空宇宙學會誌 Vol.35 No.6
초음속 공중발사 로켓의 모선분리에 대한 유동해석을 수행하였다. 전기체 형상의 모선 (F-4E Phantom)에서 분리되는 로켓주변 유동장의 정상/비정상 유동해석을 위해 압축성 Navier-Stokes 방정식이 사용되었으며, 해석결과는 모선과 로켓간의 충격파-팽창파 간섭효과를 잘 보여주고 있다. 무게중심의 변화에 따른 로켓의 거동을 예측하기 위하여 세 가지 경우에 대한 전산해석을 수행하였으며, 결과적으로 초음속 공중발사 로켓의 안전한 모선분리를 위한 설계 가이드라인을 제시하였다. An analysis is made for flow and rocket motion during a supersonic separation stage of an air-launching rocket(ALR) from the mother plane. Three-dimensional compressible Navier-Stokes equations are numerically solved to analyze the steady/unsteady flow fields around the rocket which is being separated from the mother plane configuration(F-4E Phantom). Simulation results clearly demonstrate the effect of shock-expansion wave interaction around both of the rocket and the mother plane. To predict the behavior of the ALR by the change of the center-of-gravity, three cases of numerical analysis are performed. As a result, a design-guideline of supersonic air-launching rockets for safe separation is proposed.
무게중심 변화에 따른 초음속 공중발사 로켓의 모선분리 연구
지영무(Young Moo Ji),이재우(Jae-Woo Lee),변영환(Yung Hwan Byun),박준상(Jung Sang Park) 한국유체기계학회 2006 유체기계 연구개발 발표회 논문집 Vol.- No.-
An analysis is made of flow and rocket motion during a supersonic separation stage of air-launching rocket(ALR) from the mother plane. Three-dimensional compressible Navier-Stokes equations is numerically solved to analyze the steady/unsteady flow field around the rocket which is being separated from the mother plane configuration(F-4E Phantom). The simulation results clearly demonstrate the effect of shock-expansion wave interaction between the rocket and the mother plane. To predict the behavior of the ALR according to the change of the C.G., three cases of numerical analysis are performed. As a result, a design-guideline of supersonic air-launching rocket for the safe separation is proposed.