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곽승현(Seung-Hyun Kwag),정인동(In-Dong Jung) 한국해양환경·에너지학회 2012 한국해양환경공학회 학술대회논문집 Vol.2012 No.5
Flow analysis was carried out around the end cap in the nuclear piping system. The wall thinning was due to the liquid droplet impingement erosion, which gave the leakage in the piping system. They are composed of the control valve, orifice, expander, check valve, tie-type pipe and the md-cap. Numerical simulation has been carried out to make clear the effect of liquid droplet impingement erosion to the end cap, which is passed through the orifice in the two-phase of high pressure in a power plant For the analysis, three types of models (ID,2D,3D) are applied for the comparison with the base design. Computational result shows that 2D case is the best among them because it weakens the impingement erosion. FLUENT package code was used for the hybrid multi-phase with RNG k-e turbulence model.
곽승현(Seung-Hyun Kwag),정인동(In-Dong Jung) 대한조선학회 2012 대한조선학회 학술대회자료집 Vol.2012 No.5
Flow analysis was carried out around the end cap in the nuclear piping system. The wall thinning was due to the liquid droplet impingement erosion, which gave the leakage in the piping system. They are composed of the control valve, orifice, expander, check valve, tie-type pipe and the end-cap. Numerical simulation has been carried out to make clear the effect of liquid droplet impingement erosion to the end cap, which is passed through the orifice in the two-phase of high pressure in a power plant. For the analysis, three types of models (1D,2D,3D) are applied for the comparison with the base design. Computational result shows that 2D case is the best among them because it weakens the impingement erosion. FLUENT package code was used for the hybrid multi-phase with RNG k-e turbulence model.
곽승현,Kwag, Seung-Hyun 한국마린엔지니어링학회 2007 한국마린엔지니어링학회지 Vol.31 No.6
The flow analysis was made by applying the turbulent models in the scroll volume of centrifugal compressor. The $k-{\varepsilon}.\;k-{\omega}$, Spalart-Allmaras and reynolds stress models are used in which the hybrid grid is applied for the simulation. The velocity vector the Pressure contour. the change of residual along the iteration number. and the dynamic head are simulated by solving the Navier-Stokes equations for the comparison of four example cases.
곽승현(Seung-Hyun Kwag),강선중(Sun-Joong Kang),이현우(Hyun-Woo Lee) 대한조선학회 2011 대한조선학회 학술대회자료집 Vol.2011 No.6
Three dimensional turbulent flows are numerically simulated in the inlet duct for heat recovery steam generator. The present study is aimed to analyze the effect of a variation in turbulent flow pattern by the change of roof angle in the transition duct. The finite volume based Navier-Stokes equations with unstructured grids are solved to make clear the flow dynamic phenomena. Reviews are made on with the data of path lines, velocity vectors, dynamic pressure, residuals for numerical convergence and so on. The k-epsilon, k-omega and reynolds stress are used for the generation of turbulence. Two types of roof angle are applied with and without the swirl in the duct. Turbulent flow patterns could be investigated for the optimum duct design based on the computational results.
3차원 PAR WIG (Power Augmented Ram Wing in Ground Effect)의 수치연구
곽승현(Seung-Hyun Kwag) 한국해양공학회 1997 韓國海洋工學會誌 Vol.11 No.1
A wing operating in close proximity to the ground exhibits a reduction in induced drag, which increases the lift/drag ratio. The power-augmented ram (PAR) phenomenon involves directing the efflux from forward mounted propulsion system under the wings, with the efflux nearly stagnated under the wings. In the present paper, 3-dimensional PAR was numerically studied by solving the Navier-Stokes equations. Pressure distribution and velocity vectors are calculated around the wing surface and the ground. Through the numerical simulation, Cp values and lift/drag ratio are carefully reviewed by changing the height/chord; 0.05, 0.1, 0.3 and 0.8. The shape of model is NACA 0012 with a span/chord ratio of 3.0. According to the numerical results, the relationship between lift/drag and height/chord is fairly reasonable.