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The Boundary Element Analysis of Wave Force acting on Multiple Cylinders
Namhyeong Kim,Tan Ngooc Than Cao,Soonbo Yang 한국항해항만학회 2012 한국항해항만학회지 Vol.36 No.7
In this paper, the boundary element method is applied to solve the diffraction of waves by multiple vertical cylinders under the assumption of linear wave theory. A numerical analysis by boundary element method is based on Green’s theorem and introduced to an integral equation for the fluid velocity potential around the cylinders. The numerical results obtained in this study are compared with the experimental data and the results of the theory using multiple scattering techniques. The comparisons show strong agreement. This numerical analysis method developed by using boundary element method could be used broadly for the design of various offshore structures to be constructed in coastal zones in the future.
낮은 Pe 수에서 액체금속 전열관 다발 직교유동의 열전달 상관식에 대한 수치적 평가
김남형(Namhyeong Kim),최재현(Jae Hyun Choi),신성민(Seong Min Shin),이수원(Su Won Lee),조항진(HangJin Jo) 대한기계학회 2022 대한기계학회 춘추학술대회 Vol.2022 No.11
The heat transfer correlation for a cross-flow of liquid metal over a rod bundle was numerically evaluated at low Peclet number. The two-dimensional unsteady Reynolds-averaged Navier-Stokes simulation was conducted, and the algebraic heat flux model was used for the closure of turbulent heat flux. The numerical simulation results were compared with the Kalish and Dwyer’s experiment, and it was confirmed that the results well followed the Kalish-Dwyer correlation within the applicable range, unlike the case of using the simple gradient diffusion hypothesis as the turbulent heat flux model. Based on the simulation results for the Peclet number of 10 – 40, it was shown that the heat transfer performance was well predicted by the existing Kalish-Dwyer correlation even at the lower Peclet number than the applicable range. This study allows the prediction of heat transfer in liquid metal cross-flow under the low Peclet number conditions.
낮은 Pe 수에서 액체금속 전열관 다발 직교유동의 열전달 상관식에 대한 수치적 평가
김남형(Namhyeong Kim),최재현(Jae Hyun Choi),신성민(Seong Min Shin),이수원(Su Won Lee),조항진(HangJin Jo) 대한기계학회 2022 대한기계학회 춘추학술대회 Vol.2022 No.11
The heat transfer correlation for a cross-flow of liquid metal over a rod bundle was numerically evaluated at low Peclet number. The two-dimensional unsteady Reynolds-averaged Navier-Stokes simulation was conducted, and the algebraic heat flux model was used for the closure of turbulent heat flux. The numerical simulation results were compared with the Kalish and Dwyer’s experiment, and it was confirmed that the results well followed the Kalish-Dwyer correlation within the applicable range, unlike the case of using the simple gradient diffusion hypothesis as the turbulent heat flux model. Based on the simulation results for the Peclet number of 10 – 40, it was shown that the heat transfer performance was well predicted by the existing Kalish-Dwyer correlation even at the lower Peclet number than the applicable range. This study allows the prediction of heat transfer in liquid metal cross-flow under the low Peclet number conditions.
Gisu Lee,Myeonggi Cha,Namhyeong Kim,HangJin Jo 한국방사성폐기물학회 2022 한국방사성폐기물학회 학술논문요약집 Vol.20 No.2
Recently, the deep geological disposal system isolating a spent nuclear fuel (SNF) is considered a disposal method of high-level radioactive waste for the safety of humans or the natural environment. The one of important requirements for maintaining the thermal stability of these systems is that the temperature of the buffer does not exceed 100°C even though the decay heat is emitted from highlevel radioactive wastes loaded in the disposal container. In 2007, a deep geological disposal system based on the Swedish disposal concept was developed for the SNF in Korea. To respond to the development process, the thermal stability of the deep geological disposal system developed for the disposal of domestic pressurized light water reactor (PWR) SNFs with discharged burn-up of 55 GWD/MTU was evaluated in 2019. The thing is that the recent fuel activity is pursuing to operate further high burn-up fuel conditions, and it leads to emergency core cooling system (ECCS) revision for extending the license for up to 60 or more than 60 GWD/MTU in the world. In this regard, this study evaluates numerically the thermal stability of the deep geological disposal system for the high burn-up PWR SNF having large decay heat compared to previous conditions for two different length disposal containers classified according to the length of PWR SNFs discharged from domestic nuclear power plants. A finite element analysis using a computational program was used to evaluate the thermal design requirements. Results show that both types of disposal containers would increase the temperature which reduces or fails to meet the safety margin of the disposal system. This study suggests that the design of the previous disposal system is needed to be further developed for the high burn-up PWR SNF which would be used in future nuclear power plant systems.