凹槽内剪切流动特性对滑动减阻的影响
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摘要
为了揭示凹槽内部剪切流动特性对滑动减阻效果的影响,利用静、动滑动摩擦因数测试系统和计算流体力学方法,理论、实验和数值模拟研究了凹槽高宽比(e=0.5、1.0、2.0、3.0)、凹槽几何尺寸、壁面运动速度等因素,对凹槽内的剪切流动特性及壁面滑动减阻效果的影响.研究发现,凹槽结构增加了润滑油滑动减阻效果,凹槽几何结构对减阻效果有明显影响,当凹槽宽度L、深度H均为2 mm时,凹槽的减阻效果相对较好,且壁面运动速度对其剪切力减小率fτ的影响较小.此外,凹槽尺寸、壁面滑动速度对凹槽内流场特性有重要影响,不同工况下凹槽内部存在上下2个涡或者1个大涡和2个边角涡.结果表明:凹槽内的剪切流动特性对滑动减阻效果有重要影响,并可为滑块表面凹槽结构设计提供重要的指导.
To reveal the effects of shear flow behaviors in grooves on the reduction efficiency of sliding resistance,theoretical analysis,experiments and numerical simulation were carried out using a static/dynamic sliding friction coefficient test system and computational fluid dynamic(CFD) method.The influence of groove sizes(aspect ratio of 0.5,1,2,and 3) and the velocity of sliding wall on the shear flow characteristics in grooves and the drag reduction efficiency of the sliding wall were investigated.It is found that the surface groove increases the drag reduction effect of lubrication oil,and the groove structure has significant influence on the drag reduction effect.When the width and depth are 2 mm,the groove has better drag reduction effect,and the wall sliding speed has low influence on the wall shear stress distribution.Moreover,the groove size and the wall sliding speed have important influence on the characteristics of the flow field in the groove.Under different working conditions,there are two or one large vortex and two corner vortexes in the groove.Results show that the shear flow behaviors in the groove have significant influences on the drag reduction effect,and can provide a useful guidance for the design of the groove for drag reduction.
To reveal the effects of shear flow behaviors in grooves on the reduction efficiency of sliding resistance,theoretical analysis,experiments and numerical simulation were carried out using a static/dynamic sliding friction coefficient test system and computational fluid dynamic(CFD) method.The influence of groove sizes(aspect ratio of 0.5,1,2,and 3) and the velocity of sliding wall on the shear flow characteristics in grooves and the drag reduction efficiency of the sliding wall were investigated.It is found that the surface groove increases the drag reduction effect of lubrication oil,and the groove structure has significant influence on the drag reduction effect.When the width and depth are 2 mm,the groove has better drag reduction effect,and the wall sliding speed has low influence on the wall shear stress distribution.Moreover,the groove size and the wall sliding speed have important influence on the characteristics of the flow field in the groove.Under different working conditions,there are two or one large vortex and two corner vortexes in the groove.Results show that the shear flow behaviors in the groove have significant influences on the drag reduction effect,and can provide a useful guidance for the design of the groove for drag reduction.
引文
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[23]YU H W,HUANG W,WANG X L.Dimple patterns design for different circumstances[J].Lubrication Science,2013,25(2):67-78.
[24]宋保维,郭云鹤,胡海豹,等.微结构超疏水表面减阻特性数值研究[J].计算物理,2013,30(1):70-74.SONG B W,GUO Y H,HU H B,et al.Drag reduction on micro-structured superhydrophobic surfaces[J].Chinese Journal of Computational Physics,2013,30(1):70-74.(in Chinese)
[25]WAKUDA M,YAMAUCHI Y,KANZAKI S,et al.Effect of surface texturing on friction reduction between ceramic and steel materials under lubricated sliding contact[J].Wear,2003,254(3/4):356-363.
[26]WANG X L,KATO K,ADACHI K,et al.Loads carrying capacity map for the surface texture design of Si C thrust bearing sliding in water[J].Tribology International,2003,36(3):189-197.
[27]ETSION I.Modeling of surface texturing in hydrodynamic lubrication[J].Friction,2013,1(3):195-209.
[28]PAPADOPOULOS C I,NIKOLAKOPOULOS P G,KAIKTSIS L.Evolutionary optimization of micro-thrust bearings with periodic partial trapezoidal surface texturing[J].Journal of Engineering for Gas Turbines and Power,2011,133(1):1-10.
[2]PAPADOPOULOS C I,NIKOLAKOPOULOS P G,KAIKTSIS L.Evolutionary optimization of micro-thrust bearings with periodic partial trapezoidal surface texturing[J].Journal of Engineering for Gas Turbines and Power,2011,133(1):1-10.
[3]WANG C P,FARSHID S,STEVEN T W,et al.Investigation of fluid flow out of a microcavity usingμPIV[J].Tribology Transactions,2009,52(6):817-832.
[4]TAUVIQIRRAHMAN M,ISMAIL R,JAMARI J,et al.A study of surface texturing and boundary slip on improving the load support of lubricated parallel sliding contacts[J].Acta Mech,2013,224(2):365-381.
[5]HAN J,FANG L,SUN J P,et al.Hydrodynamic lubrication of microdimple textured surface using threedimensional CFD[J].Tribology Transactions,2010,53(6):860-870.
[6]DOBRICA M B,FILLON M.About the validity of Reynolds equation and inertia effects in textured sliders of infinite width[J].Journal of Engineering Tribology,2009,223(1):69-78.
[7]RON A J,OSTAYEN V,BEEK A N,et al.Film height optimization of hydrodynamic slider bearings[C]∥International Joint Tribology Conference.San Diego:American Society of Mechanical Engineers,2007:22-24.
[8]MITIDIERI B,GOSMAN P,LOANNIDES A D,et al.CFD analysis of a low friction pocketed pad bearing[J].Journal of Tribology,2005,127(4):803-812.
[9]RAMESH A,AKRAM W,MISHRA S P,et al.Friction chracteristics of microtextured surfaces under mixed and hydrodynamic lubrication[J].Tribology International,2013,57(1):170-176.
[10]DOBRICA M B,FILLON M,PASCOVICI M D,et al.Optimizing surface texture for hydrodynamic lubricated contacts using a mass conserving numerical approach[J].Journal of Engineering Tribology,2010,224(8):737-750.
[11]TANG W,ZHOU Y,ZHU H,et al.The effect of surface texturing on reducing the friction and wear of steel under lubricated sliding contact[J].Appl Surf Sci,2013,273(5):199-204.
[12]DANIEL B,CHRISTIAN G,JOHANNES S,et al.Efficiency of laser surface texturing in the reduction of friction under mixed lubrication[J].Tribology International,2014,77(9):142-147.
[13]ARGHIR M,ROUCOU N,HELENE M,et al.Theoretical analysis of the incompressible laminar flow in a macro-roughness cell[J].Journal of Tribology,2003,125(5):309-318.
[14]SAHLIN F,GLAVATSKIH S B,ALMQVIST T,et al.Two-dimensional CFD-analysis of micro-patterned surfaces in hydrodynamic lubrication[J].Journal of Tribology,2005,127(1):96-102.
[15]MITIDIERI P,GOSMAN A D,LOANNIDES E,et al.CFD analysis of a low friction pocketed pad bearing[J].Journal of Tribology,2005,127(4):803-812.
[16]DOBRICA M B,FILLON M.About the validity of Reynolds equation and inertia effects in textured sliders of infinite width[J].Journal of Engineering Tribology,2009,223(1):69-78.
[17]HAN J,FANG L,SUN J,et al.Hydrodynamic lubrication of microdimple textured surface using threedimensional CFD[J].Tribology Transactions,2010,53(6):860-870.
[18]SHI X,NI T.Effects of groove textures on fully lubricated sliding with cavitation[J].Tribology International,2011,44(12):2022-2028.
[19]MA C,ZHU H.An optimum design model for textured surface with elliptical-shape dimples under hydrodynamic lubrication[J].Tribology International,2011,44(9):987-995.
[20]李健,周明,蔡兰,等.微结构表面上流体流动的数值模拟[J].中国机械工程,2008,19(21):2605-2608.LI J,ZHOU M,CAI L,et al.Simulation of liquid flowing over surfaces with micro-structure[J].Mechanical Engineering,2008,19(21):2605-2608.(in Chinese)
[21]TAUVIQIRRAHMAN M,ISMAIL R,JAMARI J,et al.Combined effect of texturing and boundary slippage in lubricated sliding contacts[J].Tribology International,2013,66(10):274-281.
[22]胡海豹,何强,鲍路瑶,等.二级规则微结构对低表面能纳米通道内微流动的影响[J].机械工程学报.2014,50(12):165-170.HU H B,HE Q,BAO L Y,et al.Effect of secondary regular microstructure on the micro-flows in nano-channel with low surface energy[J].Journal of Mechanical Engineering,2014,50(12):165-170.(in Chinese)
[23]YU H W,HUANG W,WANG X L.Dimple patterns design for different circumstances[J].Lubrication Science,2013,25(2):67-78.
[24]宋保维,郭云鹤,胡海豹,等.微结构超疏水表面减阻特性数值研究[J].计算物理,2013,30(1):70-74.SONG B W,GUO Y H,HU H B,et al.Drag reduction on micro-structured superhydrophobic surfaces[J].Chinese Journal of Computational Physics,2013,30(1):70-74.(in Chinese)
[25]WAKUDA M,YAMAUCHI Y,KANZAKI S,et al.Effect of surface texturing on friction reduction between ceramic and steel materials under lubricated sliding contact[J].Wear,2003,254(3/4):356-363.
[26]WANG X L,KATO K,ADACHI K,et al.Loads carrying capacity map for the surface texture design of Si C thrust bearing sliding in water[J].Tribology International,2003,36(3):189-197.
[27]ETSION I.Modeling of surface texturing in hydrodynamic lubrication[J].Friction,2013,1(3):195-209.
[28]PAPADOPOULOS C I,NIKOLAKOPOULOS P G,KAIKTSIS L.Evolutionary optimization of micro-thrust bearings with periodic partial trapezoidal surface texturing[J].Journal of Engineering for Gas Turbines and Power,2011,133(1):1-10.