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환기 공동을 이용한 수중운동체 주위의 초월 공동 다상유동장 해석
박원규(Warn-Gyu Park),김동현(Dong-Hyun Kim),정철민(Chul-Min Jung) 한국전산유체공학회 2011 한국전산유체공학회 학술대회논문집 Vol.2011 No.5
Supercavitating torpedo uses the supercavitation technology that can reduce dramatically the skin friction drag. The present work focuses on the numerical analysis of the non-condensable cavitating flow around the supercavitating torpedo. The governing equations are the Navier-Stokes equations based on the homogeneous mixture model. The cavitation model uses a new cavitation model which was developed by Merkle(2006). The multiphase flow solver uses an implicit preconditioning scheme in curvilinear coordinates. The ventilated cavitation is implemented by non-condensable gas injection on backward of cavitator cone and the base of the torpedo. The comparison between the without and with ventilated cavitation numerical results, with ventilated cavitation using non-condensable gas injection is more efficient method.
조장근,박원규,Cho, Jang-keun,Park, Warn-gyu 한국유체기계학회 1999 한국유체기계학회 논문집 Vol.2 No.2
The three-dimensional numerical study of a water jet pump was carried out to investigate the relationship between performance and the geometric variables of nozzle space, area ratio, and throat length. Because of the complex geometry, the multiblock technique was adopted for numerical analysis and a special treatment for transferring data from each of the block interfaces was implemented in order to maintain the conserved properties. To validate the present code, flow passing through a square duct with a 90-deg bend was computed, our results show good accordance with other experimental and computational results. The numerical simulation was done with the flow of the water jet pump having a 180-deg bend in order to calculate the performance at different operating conditions. The performance of the water jet pump can be improved by study of parameters which clarify the relations between the geometric variables and the flow characteristics of vortex strength and location.
최덕규(Deok-Gyu Choi),판 탄 호앙(Thanh-Hoang Phan),박성호(Sung-Ho Park),김동현(Dong-Hyun Kim),박원규(Warn-Gyu Park) 한국전산유체공학회 2021 한국전산유체공학회지 Vol.26 No.2
Understanding cavitation dynamics considering thermodynamic effect is critical to handle specific cavitation phenomena such as high temperature fluid flow or cryogenic fluid flow. In this study, a numerical analysis has been performed to investigate a the Venturi nozzle cavitation characteristic at 5 different points; 4 0℃, 50℃, 65℃, 80℃ and 95℃. A compressible homogeneous mixture model is applied, which is based on a dual-time preconditioning method. The results show that the evolution of cavitation in the Venturi nozzle and its cyclic motion can be described by re-entrant jet behavior, which is formed at a moment when high stagnation pressure occurs at the end of the cavity. After the re-entrant jet cuts off the head of the leading part, cloud shedding cavitation detaches from the main body of the cavity and it starts a vortex motion. In addition, increasing fluid temperature from 50℃ to 80℃ makes thermal effects dominant, which suppress and interrupt further development of cavitation due to the decrease of the local vapor pressure as cavitation occurs. Nonetheless, the 95℃ case, which is almost close to the boiling point of water, induces a thick and long cavity due to its higher saturated vapor pressure value when compared to others.
박영훈(Young Hun Park),김유진(Yu Jin Kim),정영만(Young Man Jung),박원규(Warn Gyu Park) 대한설비공학회 2013 대한설비공학회 학술발표대회논문집 Vol.2013 No.6
The composite electric oven is one of the fixing utensil, various functions are required. Steam generating function, which is one of its functions, and allows various food cooking. The location of the outlet of the steam generator is designed around ease of installation, consideration of internal fluid is not. Distribution of the steam can not be non-uniformly. Accordingly, cooking time becomes longer, the energy consumption increases. As a result of the analysis, it was confirmed stagnation phenomenon of the internal flow through the interpretation of the calculations for the position of the outlet of the steam generator existing. Further, by computing the analysis of various locations of the outlet of the steam generator, we investigated the distribution and characteristics of the internal flow.