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Numerical analysis of cavitating flow past an axisymmetric cylinder with comparison to experiments
Mei-Shan Jin,박원규,Chul-Min Jung 대한기계학회 2013 JOURNAL OF MECHANICAL SCIENCE AND TECHNOLOGY Vol.27 No.12
Simulation of cavitating flow is of practical importance for many engineering systems such as propellers, pump impellers, nozzles, injectors, and torpedoes. In this study, a two-phase flow solver based on a homogeneous mixture model was developed. Computations were carried out for an axisymmetric cylinder, and the present code was validated by comparing the calculation results with experimental results. The results showed that the system is suitable for simulating evaporation and condensation processes in water flow. What’s more, the changes of cavity length with various operational conditions were calculated including the water depth, angle of attack, and free stream velocity. The conditions for cavitation inception were also studied to show the relationship between the operational conditions in multiphase flows.
Numerical study of ventilated cavitating flows with free surface effects
Mei-Shan Jin,Cong-Tu Ha,박원규 대한기계학회 2013 JOURNAL OF MECHANICAL SCIENCE AND TECHNOLOGY Vol.27 No.12
Cavitating flow is usually formed on the surface of a high-speed underwater object. When the object moves near the free surface athigh speed, the cavitation signature becomes a main factor to be overcome by the sensors of a military satellite. This paper studies thefree surface effect on the ventilated cavitation process. The governing equations are Navier-Stokes equations based on a homogeneousmixture model. The multiphase flow solver used here relies on an implicit preconditioning scheme in curvilinear coordinates. The cavitationmodel used is a new cavitation model developed by Merkle et al. (2006). Computations of free surface effects were carried out witha NACA0012 hydrofoil to enable comparisons with experimental data presented in the literature. Calculations were then performed consideringthe ventilated cavitation process, including the effect of a noncondensable gas with free surface effect.
Antioxidative Constituents from Buddleia officinalis
Piao, Mei-Shan,Kim, Mi-Ran,Lee, Dong-Gun,Park, Yoonkyung,Hahm, Kyung-Soo,Moon, Young-Hee,Woo, Eun-Rhan The Pharmaceutical Society of Korea 2003 Archives of Pharmacal Research Vol.26 No.6
Four flavonoids (1-4), a phenylethyl glycoside (5), and a phenylpropanoid glycoside (6) were isolated from the flowers of Buddleia officinalis (Loganiaceae). Their structures were determined by chemical and spectral analysis. Among the isolated compounds, luteolin (1) and acteoside (6) exhibited the most potent antioxidative activity on the NBT superoxide scavenging assay. In addition, compounds 1-6 revealed weak antifungal activity, and no hemolytic activity.
Jin, Mei-Shan,Ha, Cong-Tu,Park, Warn-Gyu Elsevier 2017 INTERNATIONAL JOURNAL OF HEAT AND MASS TRANSFER - Vol.109 No.-
<P><B>Abstract</B></P> <P>A numerical study on heat transfer effects of cavitating and flashing flows was conducted by employing a compressible homogeneous mixture approach. A dual-time preconditioned method was applied to enhance the efficiency and accuracy of the computations under various flow conditions. A sensitivity analysis of the empirical coefficients used to access the predictive capability of the existing mass transfer models was assessed for cavitating flows in a converging-diverging nozzle. To confirm the use of the calibrated empirical coefficients, computations of the water flows over a cylindrical head form and a Clark-Y hydrofoil were then carried out. The results obtained indicate an overall good agreement with the experimental data. Finally, the thermal effects on the phase change process were confirmed through an examination of a flashing flow along with thermo-fluid flows. The predicted results also show a good agreement with the experimental data. In conclusion, the existing system was shown to be effective in quantitatively predicting the thermal effects of the phase change processes, and can be used to examine the hydro- and thermodynamics of multiphase flows.</P> <P><B>Highlights</B></P> <P> <UL> <LI> A numerical study of cavitating and flashing flows was conducted by employing a compressible homogeneous mixture approach. </LI> <LI> The system dominates pressure-driven vaporization and temperature-driven vaporization together. </LI> <LI> Phase change model’s dependency of model coefficients is assessed. </LI> <LI> The influence of thermal effects on evaporation process is proved by examining a flashing flow. </LI> </UL> </P>