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정요한(Y. H. Jeong),박태조(T. J. Park) 유공압건설기계학회 2014 드라이브·컨트롤 Vol.11 No.1
Hydraulic servo valves are widely used in various fluid power systems because of their fast response and precision control. In this paper, we studied the effect of metering notch shapes and amount of their openings on the flow characteristics within the spool valve using a computational fluid dynamic (CFD) code, FLUENT. To obtain the results for more realistic operating conditions, viscous heating due to the jet flow and viscosity variation of the hydraulic fluid with temperature were considered. For two types of notch shape, streamlines, oil temperature and viscosity distributions, and variations of flow and friction forces acting on spool were showed. The flow and friction forces affected by the metering notch shapes and their openings, and oil temperature rise near metering notch was significant enough to results in the jamming phenomenon. A thermohydrodynamic (THD) flow analysis adopted in this paper can be used in optimum design of hydraulic servo valves.
정요한(Y. H. Jeong ),신명준(M. J. Shin),박태조(T. J. Park),권광열(G. R. Kwon) 유공압건설기계학회 2014 유공압건설기계학회 학술대회논문집 Vol.2014 No.9
In this paper, a commercial computational fluid dynamics (CFD) code, FLUENT is used to investigate accurate flow characteristics in a direct-operated pressure relief valve. Streamline, velocity and pressure distributions, and momentum forces acting on poppet are obtained for various conditions such as inlet pressures, poppet angles and clearances. It is confirmed that, for small seat length, momentum forces can play a decisive role on the total force. As the length of the seat increases, pressure force acts dominant role.
딤플 형상이 Surface texturing한 유압부품의 윤활특성에 미치는 영향
정요한(Y. H. Jeong),김민규(M. G. Kim),박태조(T. J. Park),김현석(H. S. Kim) 유공압건설기계학회 2014 유공압건설기계학회 학술대회논문집 Vol.2014 No.9
Recently, surface texturing methods are applied to reduce friction and improve reliability of machine components such as parallel thrust bearings, mechanical face seals and piston rings etc. In this study, a thermohydrodynamic (THD) lubrication analysis is carried out to investigate the effect of dimple shapes on the lubrication characteristics of hydraulic machine components using a commercial computational fluid dynamics(CFD) code, FLUENT. The results show that the streamline, pressure and temperature distributions, friction force, load capacity and leakage for different dimple elliptical ratios.
정요한(Y. H. Jeong),이준오(J. O. Lee),박태조(T. J. Park) 유공압건설기계학회 2013 유공압건설기계학회 학술대회논문집 Vol.2013 No.6
Hydraulic spool valves are very important components in many hydraulic system. Detailed knowledge of the internal flow field and temperature distribution in the spool valve is required for their design optimization. in this paper, the flow characteristics and temperature distribution of hydraulic spool valve using a commercial computational fluid dynamics(CFD) code FLUENT are presented. To simulate the flow field and temperature distribution, three-dimensional spool-housing CFD model is adapted. The viscous heating effect caused by high-speed jet flow increases the oil temperature. Streamlines with velocity fields, temperature and viscosity distribution, oil temperature increase, flow rate and discharge coefficient with opening are showed. The results and CFD analysis method adopted in this paper can be used in optimal design of various spool valves.