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김미선(M. S. JIN),하콩투(C. T. HA),박원규(W. G. PARK),C.L. Merkle 한국유체기계학회 2010 유체기계 연구개발 발표회 논문집 Vol.2010 No.12
A hydrodynamic cavitation over converging-diverging channel is computed using the unsteady incompressible Navier-Stokes equation which based on an homogeneous mixture model. The solver employs a time marching implicit scheme and a preconditioning dual-time stepping method is used to provide high numerical stability and fast convergence. In this paper, cavitating flows over converging-diverging channel with different cavitation models are computed and the results are compared.
김미선(M.S. Jin),김호윤(H.Y. Kim),하콩투(C.T. Ha),박원규(W.G. Park) 한국전산유체공학회 2013 한국전산유체공학회지 Vol.18 No.1
Cavitating flow is usually formed on the surface of a high speed underwater object. When a object moves near a free surface at very high speed, the cavity signature becomes one of the major factors to be overcome by sensors of military satellite. The present work was to study the free surface effect on the ventilated cavitation. The governing equations were Navier-Stokes equations based on a homogeneous mixture model. The multiphase flow solver used an implicit preconditioning method in the curvilinear coordinate system. The cavitation model used here was the one first presented by Merkle et al.(2006) and redeveloped by Park & Ha(2009). Computations considered the free surface effects were carried out with a NACA0012 hydrofoil and the corresponding results were compared with the experimental data to have a good agreement. Calculations were then performed considering the ventilated cavitation, including the effect of non-condensable gas under the free surface effects.
수축-확대 노즐에서 유체 온도가 공동유동에 미치는 영향에 관한 연구
김미선(M.S. Jin),하콩투(C.T. Ha),박원규(W.G. Park) 한국전산유체공학회 2012 한국전산유체공학회 학술대회논문집 Vol.2012 No.5
Numerical analysis of cavitating flow with compressibility influence was performed to study the temperature effect on cavitation. The computations were performed within converging-diverging nozzle. In the current work, all the cavitating flows were simulated at various temperatures from room temperature to be higher by using Merkles cavitation model(2006). The governing equation was applied the preconditioned fully unsteady compressible Reynolds-Averaged Navier-Stokes equations which based on the homogeneous mixture model. The results indicate that the change of cavity length in steady state is little dependent on the temperature, but the mass flow rate and fluid velocity have significant reduce, once the fluid flows begin to through the throat of converging-diverging nozzle.
수축-확대채널 내부의 캐비테이션 유동에서 압축성 영향에 대한 해석
김미선(M.S. Jin),하콩투(C.T. Ha),박원규(W.G. Park) 한국전산유체공학회 2011 한국전산유체공학회 학술대회논문집 Vol.2011 No.11
The hydrodynamic cavitation in axisymmetric converging-diverging channel is computed using the unsteady compressible and incompressible Navier-Stokes equations with an homogeneous mixture model. A preconditioning dual-time stepping method is used for unsteady computations to insure that the method improves the high numerical stability and computational convergence in both the incompressible and compressible flow regimes. A 2-D channel grid structure is used and calculated in both incompressible and compressible flow respectively. In particular, our results validate that the compressible formulation is better than incompressible formulation to provide an improved description of cavitation dynamics.
김미선(M.S. Jin),하콩투(K.T. Ha),박원규(W.G. Park) 한국전산유체공학회 2011 한국전산유체공학회 학술대회논문집 Vol.2011 No.5
Two difference cavitation models based on the homogeneous mixture model are used to study cavitating flows through converging-diverging channel. Here, the cloud cavities, pressure distributions and other results have been obtained and compared to evaluate two cavitation models. What’s more, differences are observed in the simulated results, due to the differences in characteristics of each model. Analytical results shows that the new improvement cavitation model is validated to have better effects on simulating cavitating flows.
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.