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미세 딤플의 형상이 Laser Texturing한 평행 스러스트 베어링의 윤활특성에 미치는 영향
황윤건(Yun-Geon Hwang),박태조(Tae-Jo Park) 한국트라이볼로지학회 2009 한국트라이볼로지학회 학술대회 Vol.2009 No.11
In order to enhance the tribological performances of relatively moving parallel machine components such as parallel thrust bearings, mechanical face seals and piston rings, etc, the laser surface texturing (LST) method are widely applied now. In this paper, a commercial computational fluid dynamics(CFD) code, FLUENT is used to investigate the lubrication characteristics of parallel thrust bearing having 3-dimensional micro-dimple. And surface texture has the form of micro-dimple with selected diameter, depth and various shape. The results show that the pressure and velocity distributions, supporting load, friction force and leakage flowrate are highly affected by the number and shapes of dimple. Therefore numerical method and results can be use in design of optimum dimple characteristics to obtain maximum supporting load and minimum friction force.
다수의 미세딤플이 있는 평행 스러스트 베어링의 윤활특성 해석
황윤건(Yun-Geon Hwang),김관준(Kwan-Joon Kim),박태조(Tae-Jo Park) 한국트라이볼로지학회 2009 한국트라이볼로지학회 학술대회 Vol.2009 No.6
Laser surface texturing (LST) has emerged In the last decade, as a viable option of surface engineering. Tribology related with mechanical components such as thrust bearings, mechanical face seals and piston rings, etc, LST result in significant improvement in load capacity, wear resistance, reduction in friction coefficient. It is reported experimentally the micro-dimpled bearing surfaces can reduce friction force. However, precise theoretical results are not presented until now. In this paper, a commercial computational fluid dynamics(CFD) code, FLUENT is used to investigate the lubrication characteristics of parallel thrust bearing having 3-dimensional micro-dimple. The results show that the pressure and velocity distributions within dimples are highly affected by dimple numbers. The numerical method adopted in this paper and results can be use in design of optimum dimple characteristics.
그루브가 있는 사판식 유압피스톤 펌프용 Slipper Bearing의 윤활특성
박태조(Tae-Jo Park),황윤건(Yun-Geon Hwang),김관준(Kwan-Joon Kim),손자덕(Ja-Deok Sohn) 한국트라이볼로지학회 2009 한국트라이볼로지학회 학술대회 Vol.2009 No.6
In this thesis, FLUENT is adopted to investigate accurate flow characteristics for a tilted and grooved rotating slipper bearing which is used swash plate type hydraulic axial piston pump. Static pressure and velocity distributions, and velocity vectors are plotted for different radial groove position. In case that slipper bearing is rotating, the flow fields of tilted and grooved slipper bearing are highly asymmetrical. Static pressure, bearing load, tilting moment acting on bearing and leakage flow rate are highly affected by radial groove position, rotation of slipper bearing and film thickness. Therefore the numerical method and results adopted in this paper can be use in design of swash plate type hydraulic piston pump and further studies are required.
Groove 단면형상에 따른 유압 Spool Valve의 윤활해석
박태조(Tae-Jo Park),황윤건(Yun-Geon Hwang) 한국트라이볼로지학회 2009 한국트라이볼로지학회지 (Tribol. Lubr.) Vol.25 No.1
The spools in most hydraulic spool type control valve have several circumferential grooves to prevent well known hydraulic locking problems which result in high friction force and excessive wear. In this paper, a commercial computational fluid dynamics (CFD) code, FLUENT is used to investigate the flow and lubrication characteristics of grooved hydraulic spool valve. The stream lines and pressure distributions are obtained for various groove cross sectional shapes and film thicknesses. The stream lines are highly affected by groove cross sectional shape but pressure distributions mainly depend on the film shape and its magnitude. Therefore the numerical method adopted in this paper and results can be use in designing of various grooved spool valve.
Laser Texturing한 평행 스러스트 베어링의 윤활특성 : 제1보 - 딤플깊이의 영향
박태조(Tae-Jo Park),황윤건(Yun-Geon Hwang) 한국트라이볼로지학회 2009 한국트라이볼로지학회지 (Tribol. Lubr.) Vol.25 No.5
Laser surface texturing (LST) methods are applied recently to generate micro-dimples in machine components having parallel sliding surfaces such as thrust bearings, mechanical face seals and piston rings, etc. And it is experimentally reported by several researchers that the micro-dimpled bearing surfaces can reduce friction force. Until now, however, theoretical results for various dimple parameters are not fully presented. In this paper, a commercial computational fluid dynamics (CFD) code, FLUENT is used to investigate the effect of dimple depth on the lubrication characteristics of parallel thrust bearing. The results show that the pressure, velocity and density distributions within dimples are highly affected by dimple depths and cavitation conditions. Adoption of micro-dimple on the bearing surface can reduce the friction force highly and its levels are affected by dimple depth. The numerical methods and results can be use in design of optimum dimple characteristics to improve thrust bearing performance.
2차원 미세 포켓이 있는 무한장 Slider Bearing의 CFD 해석
박태조(Tae-Jo Park),황윤건(Yun-Geon Hwang),손자덕(Ja-Deok Sohn),정호경(Ho-Gyeong Chung) 한국트라이볼로지학회 2009 한국윤활학회지(윤활학회지) Vol.25 No.1
It is reported by many researchers that the textured bearing surfaces, where many tiny micro-pockets or enclosed recesses were incorporated, can enhance the load support and reduce friction force. Recently, the basic lubrication mechanism of micro-pocketed parallel surfaces are explained in terms of "inlet suction" using continuity equation and simply cavitation condition. However, it is required that more actual cavitation condition in the pocket region should be applied to estimate exact bearing performance. In this paper, a commercial computational fluid dynamics (CFD) code, FLUENT is used to investigate the exact lubrication characteristics of infinitely long slider bearing with micro-pockets. The results show that the pressure distributions are highly affected by pocket depths, its positions and numbers. The numerical method adopted in this paper and results can be use in optimal design of textured sliding bearings.
조현동(Hyeon-Dong Jo),황윤건(Yun-Geon Hwang),박태조(Tae-Jo Park),손자덕(Ja-Deok Sohn),정호경(Ho-Gyeong Chung) 한국트라이볼로지학회 2008 한국트라이볼로지학회 학술대회 Vol.2008 No.11
In tins paper, a deformation analysis is conducted for coaxial elastomeric seals which is adopted in the power-by-actuator for aircraft. An axisymmetric finite element contact model is developed and analyzed using MARC. The deformed seal shapes, contact stress and von-Mises stress distributions for various operating pressures, rod and cylinder clearances. The results presented an optimum design data of coaxial seals for power-by-actuator.
Laser Texturing한 평행 스러스트 베어링의 윤활특성 : 제2보 - 딤플 위치의 영향
박태조(Tae-Jo Park),황윤건(Yun-Geon Hwang) 한국트라이볼로지학회 2010 한국윤활학회지(윤활학회지) Vol.26 No.1
In the last decade, laser surface texturing (LST) has emerged as a viable option of surface engineering. Many problems related with mechanical components such as thrust bearings, mechanical face seals and piston rings, etc, LST result in significant improvement in load capacity, wear resistance and reduction in friction force. It is mainly experimentally reported the micro-dimpled bearing surfaces can reduce friction force, however, precise theoretical results are not presented until now. In this paper, a commercial computational fluid dynamics(CFD) code, FLUENT is used to investigate the lubrication characteristics of a parallel thrust bearing having 3-dimensional micro-dimple. The results show that the pressure, velocity and density distributions are highly affected by the location and number of dimple. The numerical method and results can be use in design of optimum dimple characteristics, and further researches are required.
유압 Spool Valve의 Groove 형상에 따른 윤활특성 해석
박태조(Tae-Jo Park),황윤건(Yun Geon Hwang),박경택(Kyong-Taek Park) 한국트라이볼로지학회 2007 한국트라이볼로지학회 학술대회 Vol.2007 No.11
In this paper, a commercial computational fluid dynamics(CFD) code, FLUENT is used to investigate the flow and lubrication characteristics of grooved hydraulic spool valve. The stream lines and pressure distributions are obtained for various groove shapes and film thicknesses. The stream lines are highly affected by groove shape but pressure distributions mainly depend on the film shape and its magnitude. Therefore the numerical method adopted in this paper and results can be use in designing of various grooved spool valve.
미세 포켓이 있는 무한장 Slider Bearing의 CFD 해석
박태조(Tae-Jo Park),황윤건(Yun-Geon Hwang),손자덕(Ja-Deok Sohn),정호경(Ho-Gyeong Chung) 한국트라이볼로지학회 2008 한국트라이볼로지학회 학술대회 Vol.2008 No.6
It is reported by many researchers that the textured bearing surfaces, where many tiny micro-pockets or enclosed recesses were incorporated, can enhance the load support and reduce friction force. Recently, the basic lubrication mechanism of micro-pocketed parallel surfaces are explained in terms of "inlet suction" using continuity equation and simply cavitation condition. However, it is required that more actual cavitation condition in the pocket region should be applied to estimate exact bearing performance. In this paper, a commercial computational fluid dynamics(CFD) code, FLUENT is used to investigate the exact lubrication characteristics of infinitely long slider bearing with micro-pocket. The results show that the pressure distributions are highly affected by pocket depths, its positions and numbers. The numerical method adopted in this paper and results can be use in design of textured sliding bearings.