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박일룡(I.R. Park),박대진(D.J. Park),김제인(J.I. Kim),서성부(S.B. Suh),백부근(B.G. Paik),안종우(J.W. Ahn),김기섭(K.S. Kim) 한국전산유체공학회 2020 한국전산유체공학회지 Vol.25 No.3
The cavitation inception of a two-dimensional hydrofoil is studied numerically by using the unsteady Reynolds averaged Navier-Stokes method that includes a cavitation model explaining the phase change between the water and vapour. The cavitation inceptions of the NACA0022 hydrofoil at various angles of attack are estimated after following the dependence tests of grid and turbulence model on the wetted flow around the NACA0012 section. In this paper, cavitation inception is determined when the computed cavitation volume approaches to zero value by gradually increasing cavitation number. In the numerical results, the computed sheet cavitations attached to the suction side of the hydrofoil show a close agreement with the cavitation observations in the KRISO medium-sized cavitation tunnel. Finally, the cavitation inception bucket predicted by the current cavitation simulation shows a better agreement with the experimental data than the two results of the potential flow and the minimum pressure analyses.
SUBOFF 잠수함 모델의 캐비테이션터널 조건 저항 및 자항 수치해석 연구
박일룡(I.R. Park),김제인(J.I. Kim),서성부(S.B. Suh),설한신(H.S. Seol) 한국전산유체공학회 2019 한국전산유체공학회지 Vol.24 No.3
In this paper, numerical investigation of the resistance and self-propulsion of the SUBOFF submarine model in the KRISO large cavitation tunnel was carried out by using the Reynolds averaged Navier-Stokes method and Reynolds stress model for turbulence closure. This study followed the sensitivity analysis of grid and turbulence models done by Byeon et al.[11] which was for the numerical estimation of the resistance of the SUBOFF model in DTRC towing tank. In the numerical results, the resistances and the nominal wake field were validated by the experimental data of the cavitation tunnel. After blockage corrections, the computed resistances showed a good accordance with those of the DTRC towing tank test free from blockage effects. Self-propulsion simulations for wetted and cavitating flow conditions were performed on the basis of thrust identity approach and resulted in a good agreement with the measured self-propulsion data and cavitation observations for the propeller.
박일룡(I.R. Park),임근태(G.T. Yim),김제인(J.I. Kim),박철수(C.S. Park) 한국전산유체공학회 2020 한국전산유체공학회지 Vol.25 No.1
Numerical investigations of bubble column flows were performed to validate the predictive capabilities of the commercial CFD solver STAR-CCM+. An Eulerian-Eulerian approach was used for the simulation of the two-phase flow in a bubble column. The numerical method takes into account interactive forces between both phases: drag force, lift force, turbulent dispersion force and wall lubrication force near the wall surface. The constituent moments of bubble size distribution function are transported with individual phase velocities with breakup and coalescence models to account for size dependent bubble motion. In the numerical results, the dependances of turbulence and lift models on the solutions were investigated. Validation of the present simulation results against available experimental and numerical data was carried out with respect to bubble plume oscillation, liquid velocity and gas hold-up. Finally, a reasonable agreement between the simulation and experimental results was obtained.
수상 함정 기포 마스크 벨트에서 생성된 기포 유동에 관한 수치해석 연구
박일룡(I.R. Park),김제인(J.I. Kim),박철수(C.S. Park),김건도(G.D. Kim),임근태(G.T. Yim) 한국전산유체공학회 2021 한국전산유체공학회지 Vol.26 No.3
This paper provides the results of the basic numerical study on the bubble generation mechanism of an air bubble mask belt device to reduce engine noise by creating bubble curtain around the hull of a surface ship. To analyze two-phase flows, a large eddy simulation (LES) approach coupled with a volume of fluid (VOF) method was adopted. This numerical approach was verified by comparison with the experimental and other numerical results for a single bubble rising problem in a stationary flow field. Due to laminar and turbulent break-up phenomena, the bubble mask belt produced bubbles of various sizes ranging from 100μm to 3000μm depending on the flow conditions. The present numerical results will be used to determine the air flow rate of the mask belt and other flow conditions required to generate a desired size bubble at a given ship speed.
RANS법을 이용한 DARPA Suboff 잠수함의 저항 및 자항 해석
변창용(C.Y. Byeon),김제인(J.I. Kim),박일룡(I.R. Park),설한신(H.S. Seol) 한국전산유체공학회 2018 한국전산유체공학회지 Vol.23 No.3
This paper shows numerical results of the resistance performance of the DARPA Suboff submarine model and the open water performance of the E1619 propeller obtained by using Reynolds averaged Navier-Stokes method. A grid dependency study was carried out for the both simulations with varying turbulence models: Realizable k-ε model, SST k-ω model and Reynolds Stress model. Resistances of the submarine model and the propeller characteristics of the E1619 as well as their local flows were compared with available experimental data. The present numerical results from Reynolds stress model on fine grids of y+ 1 were well matched with those of model test and other numerical study. The wake velocities behind the submarine and the propeller were compared with LDV measurement data showing good agreement. Finally, self-propulsion of the DARPA Suboff submarine equipped with the E1619 was simulated. The analysed several self-propulsion factors were compared with other numerical results.