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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.
자동차 Defrost 노즐 유동의 설계인자에 대한 수치적 연구
박원규(Warn-Gyu Park),배인호(In-Ho Bae) 한국자동차공학회 2003 한국 자동차공학회논문집 Vol.11 No.1
The frost and mist in the windshield disturb the sight of driver and passengers especially in wintel. This possibly leads to safety problems. In order to export automobiles to the countries of North America, the safety regulation requires the frost of selected area should be completely melted in 3O minutes. The defrost pattern and time for melting of frost are fully dependent on the flow and temperature field near the windshield. Furthermore, the flow and temperature field near the windshield are dependent on the air discharged from defrost nozzle. The present work has been done for understanding the flow features of the discharged air and internal f1ow within the nozzle duct. The three dimensional Navier-Stokes code was used for performing the generic A/C duct flow analysis. The present results were nearly coincided with experimental data. To perform the parametric study of the effectiveness of the number of guide vanes, the discharge angle and the location of nozzle were changed. The ratio of volume flow rate through defrost nozzle and side exit were compared to investigate the influence of parameters on the effectiveness of defrost nozzle. The velocity profiles and flow patterns of the defrost nozzle duct were also analyzed.
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.
박형만(Hyung-Man Park),박원규(Warn-Gyu Park),정철민(Chul-Min Jung) 대한조선학회 2011 대한조선학회 학술대회자료집 Vol.2011 No.6
Cavitating flow simulation is of practical importance for many hydraulic engineering system, such as turbine, nozzles, injectors, torpedoes, etc. The present work focuses on the numerical analysis of the multiphase flow around the underwater vehicle with angles of attack. The governing equation is the Navier-Stokes equation with a homogeneous mixture model. The cavitation model uses new cavitation model which is developed by Merkle(2006). The multiphase flow solver uses an implicit preconditioning scheme in curvilinear coordinate. For the code validation, the results from the present work are compared with the existing experimental results. The multiphase flow around the underwater vehicle is simulated which includes several angles of attack.
강태진(Tae-Jin Kang),박원규(Warn-Gyu Park) 대한조선학회 2011 대한조선학회 학술대회자료집 Vol.2011 No.6
The cavitating flow simulation is of practical importance for many engineering systems, such as pump, turbine, nozzle, injector, etc. In the present work, a solver for two-phase flows has been developed and applied to simulate the cavitating flows past hydrofoil. The governing equation is the Navier-Stokes equation based on homogeneous mixture model. The solver employs an implicit preconditioning, dual time stepping algorithm in curvilinear coordinates. An experimental data was compared with the present results to validate the present solver. This study could be confirmed characteristic of hydrodynamic coefficients with change of the angle of attack. It is concluded that the present numerical code has successfully accounted for two-phase Navier-Stokes model of cavitation flow.