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S-duct 내부유동의 출구경계조건 및 난류모델의 영향검토
홍승규(S. K. Hong),이광섭(K. S. Lee) 한국전산유체공학회 2000 한국전산유체공학회 학술대회논문집 Vol.2000 No.5
An S-duct flow is subjected to an entrance flow of Mach 0.6. The duct turns 30˚ and reverses its turn by 30˚, followed by a straight section. Such an internal flow induces a secondary flow due to curvature effect. Goal of this paper is to show the sensitivity of outflow boundary conditions on the quality of numerical solutions as well as to show curvature effect on the flow field. The often-used Baldwin-Lomax turbulence model is shown to be less functional on the concave region when the secondary flow has its strong influence.
CFDS기법에 연계된 특성경계조건의 응용성에 대한 소개
홍승규(S. K. Hong),이광섭(K. S. Lee) 한국전산유체공학회 2000 한국전산유체공학회지 Vol.5 No.1
Characteristic boundary conditions are discussed in conjunction with a flux-difference splitting formulation as modified from Roe's linearization. Details of how one can implement the characteristic boundary conditions which are made compatible with the interior point formulation are described for different types of boundaries including subsonic outflow and adiabatic wall. The validity of boundary conditions are demonstrated through computation of transonic airfoil, supersonic ogive-cylinder, hypersonic cylinder, and S-duct internal flows. The computed wall pressure distributions are compared with published experimental and computed data. Objectives of this paper are thus to give insight of formulation procedure of a flux-difference splitting method and to pave ways for other users to adopt present boundary procedure on their numerical methods.
김유진(E. Kim),박수형(S.H. Park),권장혁(J.H. Kwon),김성인(S.I. Kim),박승오(S.O. Park),이광섭(K.S. Lee),홍승규(S.K. Hong) 한국전산유체공학회 2004 한국전산유체공학회지 Vol.9 No.2
A numerical study of under expanded jet and impingement on a wall mounted at various distances from the nozzle exit is presented. The 3-dimensional Navier-Stokes equations and k-ω turbulence equations are solved. The grids are constructed as overlapped grid systems to examine the distance effect. The DADI method is applied to obtain steady-state solutions. To avoid numerical instability such as the carbuncle phenomena that sometimes accompany approximate Riemann solver, the HLLE+ scheme is employed for the inviscid flux at the cell interfaces. A goal of this work is to apply a number of two-equation turbulence models based on the ω equation to the impinging jet problem.
초음속 충돌 제트 운동에 대한 k-$\omega$ 난류모델의 적용
김유진,박수형,권장혁,김성인,박승오,이광섭,홍승규,Kim E.,Park S. H.,Kwon J. H.,Kim S. I.,Park S. O.,Lee K. S.,Hong S. G. 한국전산유체공학회 2004 한국전산유체공학회지 Vol.9 No.2
A numerical study of underexpanded jet and impingement on a wall mounted at various distances from the nozzle exit is presented. The 3-dimensional Wavier-Stokes equations and κ-ω turbulence equations are solved. The grids are constructed as overlapped grid systems to examine the distance effect. The DADI method is applied to obtain steady-state solutions. To avoid numerical instability such as the carbuncle phenomena that sometimes accompany approximate Riemann solver, the HLLE+ scheme is employed for the inviscid flux at the cell interfaces. A goal of this work is to apply a number of two-equation turbulence models based on the w equation to the impinging jet problem.
김유진(E. Kim),박수형(S. H. Park),권장혁(J. H. Kwon),김성인(S. I. Kim),박승오(S. O. Park),이광섭(K. S. Lee),홍승규(S. K. Hong) 한국전산유체공학회 2004 한국전산유체공학회 학술대회논문집 Vol.2004 No.-
A numerical study of underexpanded jet and impingement on a wall mounted at various distances from the nozzle exit is presented. The 3-dimensional Navier-Stokes equations and k-ω turbulence equations are solved. The grids are constructed as overlapped grid systems to examine the distance effect. The DADI method is applied to obtain steady-state solutions. To avoid numerical instability such as the carbuncle that sometimes accompany approximate Riemann solver, the HLLE+ scheme is employed for the inviscid flux at the cell interfaces. A goal of this work is to apply a number of two-equation turbulence models based on the ω equation to the impinging jet problem.
홍승규(S. K. Hong),성웅제(W. J. Sung) 한국전산유체공학회 2001 한국전산유체공학회지 Vol.6 No.3
For rapid and abrupt control of a missile in supersonic flight, side jet on a missile body is found to be a useful device as evidenced by recent missile development at several nations. The magnitude of the side jet and the duration of it decide the level of control of such a missile system. In this paper, the aerodynamic characteristics of the side jet device itself are examined in terms of key parameters such as the side jet nozzle geometry, the chamber pressure and temperature. Specifically attention is paid to the effect of the chamber shape between the straight nozzle and the bent nozzle by 90 degrees on the nozzle flow properties. The thrust magnitudes are compared between the two shapes. Whether the way the nozzle is bent at the joint affects the nozzle performance is also investigated, Effects of the length and the divergence angle of the nozzle on the thrust are also quantified among three different side jet nozzles.
[특집 : 연구실 소개] ADD 공기역학팀의 업무 소개
홍승규(S. K. Hong) 한국전산유체공학회 2002 한국전산유체공학회지 Vol.7 No.1
ADD의 유도무기 개발을 위하여 형상설계가 필요하고, 형상설계 및 성능해석에는 정확한 공력계수의 예측이 필수적이다. 이외에도 CFD의 역할이 점점 증대하여 지상실험으로 입증하기 어려운 유동장을 해석함으로써 중요한 설계 parameter를 제공하고 있다. 본 기고에서는 이러한 공력팀의 역할을 간단히 소개하고자 한다.
Simulation of Jet Plume Impinging onto a Duct
홍승규(S.K. Hong),이광섭(K.S. Lee),백동기(D.K. Back) 한국전산유체공학회 1997 한국전산유체공학회지 Vol.2 No.2
Accurate simulation of jet plume exhausting into the open space as well as onto the opposing wall is of interest both numerically and physically; the latter, from a system designer's point of view. In the current work, Navier-Stokes computation is undertaken to capture the flow pattern of a supersonic jet impinging onto a rectangular duct which deflects the vertical jet horizontally. Of particular interest are the flow structure in the jet exhaust area, pressure pattern and the magnitude of pressure force at the bottom wall. Usefulness of present characteristic boundary condition applied at the exiting plane of the duct is demonstrated by capturing such complex flow structures for different lengths of the deflection duct.
Simulation of Jet Plume Impinging onto a Duct
홍승규(S.K. Hong),이광섭(K.S. Lee),백동기(D.K. Back) 한국전산유체공학회 1997 한국전산유체공학회지 Vol.2 No.2
Accurate simulation of jet plume exhausting into the open space as well as onto the opposing wall is of interest both numerically and physically; the latter, from a system designer's point of view. In the current work, Navier-Stokes computation is undertaken to capture the flow pattern of a supersonic jet impinging onto a rectangular duct which deflects the vertical jet horizontally. Of particular interest are the flow structure in the jet exhaust area, pressure pattern and the magnitude of pressure force at the bottom wall. Usefulness of present characteristic boundary condition applied at the exiting plane of the duct is demonstrated by capturing such complex flow structures for different lengths of the deflection duct.
초음속 유도탄의 측추력기 작동시 풍동실험을 위한 CFD 해석 연구
홍승규(S.K. Hong),성웅제(W.J. Sung) 한국전산유체공학회 2002 한국전산유체공학회 학술대회논문집 Vol.2002 No.-
Computational study has been undertaken to investigate the aerodynamic influence of side jet on a supersonic missile and to find a similarity condition between the flight condition and the wind tunnel testing. Tasks were performed to validate the existing Raytheon test body with side jet, to simulate the flow inside the supersonic wind tunnel, and to compare the flow fields between the missile in free flight and that in the wind tunnel. Then sub-scale model of body-tail configuration was analyzed to estimate the influence of the side jet on the missile components. It is found that the influence of side jet is not as significant on the tail region as on the body surface and a simple algebraic formula for aerodynamic coefficients accounting for the side jet as a point force may be cautiously utilized in setting up control logic.