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서로 다른 두 개의 공동모델의 모델 상수값이 공동의 길이에 미치는 영향연구
김미선(M. S. Jin),하콩투(C. T. Ha),박원규(W. G. Park),정철민(C. M. Jung) 한국전산유체공학회 2012 한국전산유체공학회지 Vol.17 No.3
This work was devoted to compare two different cavitation models to study the dependency of model constants. The cavitation model of Merkle et al.(2006) and Kunz et al.(2000) were used for the present computational study. The cavitation models were coupled with the incompressible unsteady Reynolds-Averaged Navier-Stokes solver to indicate the vaporization and condensation processes. For this purpose, a preconditioning method was added as the pseudo-time term to solve the unsteady stiffness problems. For the validation of the numerical simulation, the computation was performed for the cavitating flow in a converging-diverging channel. The present results show that Merkle’s cavitation model is independent to the model constants, and the higher numerical accuracy over Kunz’s cavitation model.
전산해석과 실험의 비교검증을 통한 원통형 수중운동체 주위의 캐비테이션 유동현상 연구
박형만(H.M. Park),박원규(W.G. Park),정철민(C.M. Jung) 한국전산유체공학회 2012 한국전산유체공학회지 Vol.17 No.1
Cavitation causes a great deal of noise, damage to components, vibrations, and a loss of efficiency in devices, such as propellers, pump impellers, nozzles, injectors, torpedoes, etc., Thus, cavitating flow simulation is of practical importance for many engineering systems. In this study, a two-phase flow solver based on the homogeneous mixture model has been developed. The flow characteristics around an axisymmetric cylinder were calculated and then validated by comparing with the experimental results in the cavitation water tunnel at the Korea Ocean Research & Development Institute. The results show that this solver is highly suitable for simulating the cavitating flows. After the code validation, the cavity length with changes of water depth, angle of attack and velocity were obtained.. Cavitation inception was also calculated for various operational conditions.
서로 다른 캐비테이션 모델을 이용한 실린더 주위의 캐비테이션 유동현상 전산해석
김승윤(S.Y. Kim),박원규(W.G. Park),정철민(C.M. Jung) 한국전산유체공학회 2011 한국전산유체공학회지 Vol.16 No.1
Engineering interests of submerged bodies and turbomachinery has led researchers to study various cavitation models for decades. The governing equations used for the present work are the two-phase Navier-Stokes equations with homogeneous mixture model. The solver employed on implicit dual time preconditioning algorithm in curvilinear coordinates. Three different cavitation models were applied to two axisymmetric cylinders and compared with experiments. It is concluded that the Merkle's new cavitation model has successfully accounted for cavitating flows and well captured the re-entrant jet phenomenon over the 0-caliber cylinder.
동유체력 계산을 이용한 수중운동체의 횡동요 계수 변화 예측
김태우(T. W. Kim),강태진(T. J. Kang),박원규(W. G. Park),정철민(C. M. Jung) 한국전산유체공학회 2015 한국전산유체공학회지 Vol.20 No.2
For Underwater vehicles, Unwanted roll excursions are inevitable as they are caused by induced propeller torque, disturbances, and banking motion during turns. To estimate the manoeuvring performance of underwater vehicle, it is necessary to obtain the roll coefficient of body. This paper was covered estimation of roll coefficient of underwater vehicle using STAR-CCM+, commercial CFD(Computational Fluid Dynamics) code. The RANS equations for incompressible fluid flows was solved numerically by using a finite volume method. An MRF(Moving Reference Frame) Method was Also adopted for rotations of body. For the validation, the flow around a DARPA SUBOFF bare hull model was simulated and good agreement with experiments was obtained. And Pure roll coefficients were calculated and campared with the experimental data which were presented by Seoul National University. Finally, an underwater vehicle model with propeller was simulated and analyzed for estimation of roll coefficient variation caused by induced propeller torque.
강태진(T.J. Kang),박원규(W.G. Park),정철민(C.M. Jung) 한국전산유체공학회 2014 한국전산유체공학회지 Vol.19 No.2
Cavitation causes a great deal of noise, damage to components, vibrations, and a loss of efficiency in devices, such as propellers, pump impellers, nozzles, injectors, torpedoes, etc. Thus, the cavitating flow simulation is of practical importance for many engineering systems. In the present work, a two-phase flow solver based on the homogeneous mixture model has been developed. The solver employs an implicit preconditioning, dual time stepping algorithm in curvilinear coordinates. The flow characteristics around Clark-Y hydrofoil were calculated and then validated by comparing with the experimental data. The lift and drag coefficients with changes of angle of attack and cavitation number were obtained. The results show that cavity length and lift, drag coefficient increase with increasing angle of attack.