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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.
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.
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.
압축성 효과를 고려한 고속 수중운동체 주위의 환기공동을 포함하는 다상유동장 해석
김동현(D.H. Kim),박원규(W.G Park),정철민(C.M, Jung) 한국전산유체공학회 2012 한국전산유체공학회 학술대회논문집 Vol.2012 No.11
Supercavitating underwater vehicle uses the supercavitation technology that can reduce dramatically the skin friction drag. The present work focuses on the numerical analysis of the multi-phase flow around the supercavitating underwater vehicle with ventilated cavitation. The governing equations are the Navier-Stokes equations based on the homogeneous mixture model. The governing equation is comprised of the continuity equation for liquid, vapor and non-condensable/exhaust gas phase. The cavitation model uses a new cavitation model which was developed by Merkle(2006). The present work shows that the higher injection of the non-condensable gas induced stronger instability of the ventilated cavity. Comparison between experimental data and numerical analysis with compressible effect, the code has good ability to handle multi-phase cavitating flow, as well as incompressible.
박수일(S.I. Park),박원규(W.G. Park),정철민(C.M. Jung) 한국전산유체공학회 2009 한국전산유체공학회 학술대회논문집 Vol.2009 No.11
A massive cavity is generated behind the underwater vehicles, such as marine propellers, pump impellers, nozzles, injectors, torpedoes, etc. when a underwater vehicle moves at very high speed in the underwater. At this point it makes supercavitating flow and the nose, ie., the cavitator is very important fator at the vehicle since it should be surrounded by the cavity. The present work has focused on the simulation of cavitation flow using the new cavitator. The governing equation is the Navier-Stokes equation based on homogeneous mixture model. For the code validation, the results from the present solver have been compared with experiments and other numerical results. A fairly good agreement with the experimental data and other numerical results have been obtained.