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Experimental and Computational Investigation of the Flow around a Circular Cylinder
Mu-Seok Song(송무석),Geun-Tae Yim(임근태),Wu-Joan Kim(김우전) 한국해양공학회 1997 韓國海洋工學會誌 Vol.11 No.4
원형주상체 주위의 유동을 규명하기 위해 회류수조에서 원주방향으로 24개의 위치에 대하여 압력을 계측하였으며, laser sheet을 이용하여 유동을 가시화 하였다. Reynolds수가 4800에서 40000인 범위에 대하여 실험을 수행하였다. 또한, 원형단면체 주위의 비정상 층류유동에 대한 Navier-Stokes방정식의 해를 구하는 수치해석기법을 개발하였다. 효과적인 격자배치를 위하여 H와 O-type의 중첩격자를 사용하였고, 이산화 방법으로는 정규격자시스템에서 유한차분법을 적용하였다. 실험과 수치해석결과에서 뚜렷한 와류박리현상을 볼 수 있었으며, 압력계수(Cp), 항력계수(CD), 스트로얼수(St)를 정량적으로 비교하였을 때, 비교적 잘 일치하는 것을 확인하였다. The flow around a circular cylinder is investigated both experimentally and numerically. The experiment performed in a circulating water channel facility includes pressure measurements at 24 locations along the circumference of the cylinder and flow visualizations by using laser sheet. The Reynolds number ranges from 4800 to 40000. Also a numerical method was developed to solve the Navier-Stokes equations for unsteady laminar flows around the circular cylinder. The present method used the finite-difference scheme in the collocated grid system and the pressure-Poisson method was employed to obtain divergence-free velocity field at each time step. For an efficient grid distribution a composite griding with H- and O-type grids was used.<br/> Vortex sheddings are nicely captured both in experiments and calculations and the integrated values are quite comparable. Visualized flow patterns are believed to be quite helpful to understand the overall picture of the flow but, in order to become more informative, problems associated with synchronization and resolution should be reconsidered. Composite overlaying grid was efficiently used without a significant accuracy loss and, on the whole, our numerical method predicted the flow field well. Maximum drag occurs nearly when the lift is maximum (or minimum) but the minimum drag occurs when attached vortices start growing so the lift is rather close to zero.
터렛 계류된 부유체의 과대 선수동요에 관한 실험 및 수치해석 연구
홍장표(Jang-Pyo Hong),남보우(Bo Woo Nam),성홍근(Hong-Gun Sung),송무석(Mu-Seok Song),조석규(Seok-Kyu Cho) 한국해양환경·에너지학회 2012 한국해양환경공학회 학술대회논문집 Vol.2012 No.5
The excessive yaw motion of turret moored vessel is investigated. The floating body is moored by internal turret and catenary mooring. The experiments are conducted in regular waves. Turret moored vessel can oscillate side to side or move to one direction, large yaw motion. The results shows that the excessive yaw occurs for particular condition, ratio of wave lengths and wave period. The time series, comparison of moments and time domain analysis are performed. The analysis shows that force and ratio of wave lengths and vessel length influence the excessive yaw motion. The static analysis and time domain of excessive yaw motion.
터렛 계류된 부유체의 과대 선수동요에 관한 실험 및 수치해석 연구
홍장표(Jang-Pyo Hong),남보우(Bo Woo Nam),성홍근(Hong-Gun Sung),송무석(Mu-Seok Song),조석규(Seok-Kyu Cho) 대한조선학회 2012 대한조선학회 학술대회자료집 Vol.2012 No.5
The excessive yaw motion of turret moored vessel is investigated. The floating body is moored by internal turret and catenary mooring. The experiments are conducted in regular waves. Turret moored vessel can oscillate side to side or move to one direction, large yaw motion. The results shows that the excessive yaw occurs for particular condition, ratio of wave lengths and wave period. The time series, comparison of moments and time domain analysis are performed. The analysis shows that force and ratio of wave lengths and vessel length influence the excessive yaw motion. The static analysis and time domain analysis results indicate that wave drift moment is the main parameter of excessive yaw motion.
예인수조를 이용한 조류발전 터빈의 동력 계측 및 비교 연구
도인록(In-Rok Do),김문찬(Moon-Chan Kim),이승기(Seung-Ki Lee),현범수(Beom-Soo Hyun),이신형(Shin-Hyung Rhee),송무석(Mu-seok Song) 대한조선학회 2011 대한조선학회 학술대회자료집 Vol.2011 No.6
본 논문은 100kW 용량의 조류발전용 HAT 임펠러의 성능평가에 관한 실험적 연구를 수행하였다. 실험은 지름 700mm의 3가지 모형 모델을 이용하여 부산대학교의 100m 예인전차에서 실행되었다. 모형 모델의 T.S.R을 변화시켜 실험을 시행하여 정성적이고 정량적인 동력계수의 실험 결과 값을 얻고, 각 case의 실험 결과들을 상호 비교 하였다. 향후 수치해석 결과와 실험결과 와의 차이에 대한 보다 자세한 검증을 수행할 계획이다. The experimental study for the performances of a 100kW marine current turbines(Horizontal Axis Turbine) have been conducted with the 700mm diameter models in PNU 100m towing tank. The quantitative and also qualitative test results of power coefficient have been obtained according to the variation of tip speed ratio. The test results were compared among the model impellers of 3 cases. The more detail validation for the present experimental study would be expected in a near future for the difference between the computation and experiment.