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유체력 모델과 조종 운동 시뮬레이션을 통한 수상함의 조종성능 추정에 관한 연구
여홍구(H. Yeo),박종열(J. Park),석우찬(W. Seok),이신형(S.H. Rhee),박성찬(S.-C. Park) 한국전산유체공학회 2020 한국전산유체공학회지 Vol.25 No.4
In this study, empirical formulae for estimating maneuvering coefficients in the mathematical maneuvering model were modified for surface combatants. The three-degrees-of-freedom model suggested by the Mathematical Modeling Group (MMG) was introduced for predicting maneuverability of two naval surface combatant models. The maneuvering coefficients were obtained by the empirical formulae adjusted based on captive model test results to reflect such slender and fast surface combatants’ hull design characteristics. In the maneuvering simulation by the modified empirical formulae, the maneuverability criteria showed good agreement with the experimental database.
해파리 추진 방식을 응용한 합성 제트 추진기 형상 설계 및 분석
이혁수(H. Lee),장진관(J. Jang),석우찬(W. Seok),여홍구(H.G. Yeo),이신형(S.H. Rhee) 한국전산유체공학회 2020 한국전산유체공학회지 Vol.25 No.1
Synthetic jet thrusters are zero-net mass flux thrusters for low speed underwater vehicles inspired by the pulsatile jet propulsion of jellyfish and squid. In this paper, OpenFOAM libraries are used to analyze vortex ring formation and energy efficiency of synthetic jet thrusters with varying diameters and lengths of nozzles. Synthetic jet thrusters are modeled in the axisymmetric domain and dynamic mesh is used to simulate the sinusoidal motion of pistons. The flow field, circulation, and ratio of the change in kinetic energy to the piston work are computed during the first two cycles of moving piston. As a result, the vortex ring formation is enhanced by the change in velocity distribution at the nozzle exit due to the flow generated in the relaxation phase. Furthermore, the nozzle with the diameter ratio of 0.6 and zero-length shows the highest efficiency.
해석 기법에 따른 KVLCC2 선형의 저항 및 사항 시험에 관한 비교 연구
이인수(I. Lee),석우찬(W. Seok),여홍구(H. Yeo),조용재(Y.J. Cho),이신형(S.H. Rhee) 한국전산유체공학회 2020 한국전산유체공학회지 Vol.25 No.1
In this study, comparative studies between double-body and VOF methods were performed using SNUFOAM, specialized in fluid dynamics problems in naval architecture and ocean engineering.Although the double-body method is more efficient in terms of computational resources than the VOF method, but free surface effect was ignored. For comparative studies, resistance tests and static drift tests at drift angle 4° and 12° for a KVLCC2 was conducted. They showed differences in forces and moments and pressure, wall shear stress and skin friction lines were identified to investigate the differences.