Reduction of drag torque in disengaged wet clutches is essential for transmission research because it is one of the potentials of efficiency improvement. Aeration of oil film between two closely rotating plates promotes the decrease of drag torque at high speed region. The effects of surface tension and static contact angles during aeration are non-negligible showed by test results. The traditional lubrication model does not adequately predict the experimental results with different surface tension and contact angles during aeration. Hence, in this present paper, contact angles between Aluminum and Teflon materials were firstly measured, and the drag torques under two different contact angles were examined experimentally. An improved lubrication model of drag torque based on Navier-Stokes equations at the gas-liquid interface was built. The lubrication boundary condition was modified to introduce the effects of surface tension and contact angle. The model shows that the effects at the beginning of aeration of oil film are significant. These effects almost occur at stationary plate due to low Reynolds number and Weber number. The model shows that an increase in the surface tension promotes aeration, but does not affect the peak drag torque. Increasing contact angle also promotes the aeration, and accelerates the decrease of drag torque. The larger contact angle is, the smaller the peak drag torque will be. A computational fluid dynamics (CFD) model based on volume of fluid (VOF) method was presented to validate the interface shape when aeration occurs. The model prediction has a good agreement with experimental observations for Aluminum plates and Teflon plates. The modified lubrication model of drag torque gives a convenient description of the effects of surface tension and contact angel, and lays down a frame to understand the beginning of aeration.
Zengxiong Peng
,
Shihua Yuan
. Mathematical Model of Drag Torque with Surface Tension in Single-Plate Wet Clutch[J]. Chinese Journal of Mechanical Engineering, 2019
, 32(2)
: 25
-25
.
DOI: 10.1186/s10033-019-0343-9
[1] H Hashimoto, S Wada, Y Murayama. The performance of a turbulent-lubricated sliding bearing subject to centrifugal effect. Trans. Jpn. Soc. Mech. Eng. Ser. C, 1984, 49(446):1753-1761. (in Japanese)
[2] Y Kato, T Murasugi, H Hirano, et al. Fuel economy improvement through tribological analysis of the wet clutches and brakes of an automatic transmission. Society of Automotive Engineers of Japan, 1993, 16(12):57-60.
[3] C R Chinar, Jinhyun Cho, W W Schultz, et al. Modeling and parametric study of torque in open clutch plates. Journal of Tribology, 2006, 128(2):422-430.
[4] H Kitabayashi, Yuli Chen, H Hiraki. Analysis of the various factors affecting drag torque in multiple-plate wet clutches. JSAE/SAE International Spring Fuels & Lubricants Meeting, Yokahama, Japan, May 19-22, 2003:1-6.
[5] J S Ryu, I H Sung. Effect of angle and density of grooves between friction plate segments on drag torque in wet clutch of automatic transmission. J. Korean Soc. Tribol. Lubr. Eng., 2014, 30(2):71-76. (in Korean)
[6] Ryu J S, I H Sung. Effects of friction plate area and clearance on the drag torque in a wet clutch for an automatic transmission. J. Korean Soc. Tribol. Lubr. Eng., 2014, 30(6):337-342. (in Korean)
[7] I S qbal, F Al-bender, B Pluymers, et al. Experimental characterization of drag torque in open multi-disks wet clutches. SAE International Journal of Fuels and Lubricants, 2013, 6(3):894-906.
[8] Yiqing Yuan, Pradeep, Dong Yu. CFD simulation of the flows within disengaged wet clutch of an automatic transmission. SAE World Congress, Michigan, USA, March 3-6, 2003:1-6.
[9] Yiqing Yuan, Eysion Liu, H James. An improved hydrodynamic model for open wet transmission clutches. Journal of Fluids Engineering, 2007, 129(3):333-337.
[10] Jibin Hu, Zengxiong Peng, Shihua Yu. Drag torque prediction model for the wet clutches. Chinese Journal of Mechanical Engineering, 2009, 22(2):238-243.
[11] Shihua Yuan, Zengixong Peng, Chongbo Jing. Experimental research and mathematical model of drag torque in single-plate wet clutch. Chinese Journal of Mechanical Engineering, 2011, 24(1):91-97.
[12] Shihua Yuan, Kai Guo, Jibin Hu, et al. Study on aeration for disengaged wet clutches using a two-phase flow model. Journal of Fluids Engineering-Transactions of the ASME, 2010, 132(11):111304-1-111304-6.
[13] Jibin Hu, Zengxiong Peng, Chao Wei. Experimental research on drag torque for single-plate wet clutch. Journal of Tribology-Transactions of the ASME, 2012, 134(1):014502-1-014502-6.
[14] Jinshi Chang. A calculation formula for carrying-capacity of annular hydrostatic step-bearing taking account of oil-flow inertia. Journal of Mechanical Engineering, 1982, 18(1):62-68. (in Chinese)
[15] J G Robert. Contact angle, wetting, and adhesion:a critical review. Journal of Adhesion Science and Technology, 1992, 6(12):1269-1302.MathSciNet
[16] Xiaodong Wang, Xiaofeng Peng, Duzhong Lee. Dynamic wetting and stress singularity on contact line. Science in China, 2003, 46(4):407-415.
[17] Y D Shikhmurzaev. The moving contact line on a smooth solid surface. International Journal of Multiphase Flow, 1993, 19(4):589-610.
[18] V Gauri, K W Koelling. The motion of long bubbles through viscoelastic fluids in capillary tubes. Rheologica Acta, 1999, 38(5):458-470.
[19] C W Hirt, B D Nichols. Volume of fluid (VOF) method for the dynamic of free boundaries. Journal of Computational Physics, 1981, 39(1):201-225.
[20] Yu-ting Ma, Zhi-guo Pei, Zhong-xiang Chen. Multi-field analysis and experimental verification on piezoelectric valve-less pumps actuated by centrifugal force. Chinese Journal of Mechanical Engineering, 2017, 30(4):1032-1043.
[21] R A Chinar, W S William, L C Steven. Aeration in lubrication with application to drag torque reduction. Journal of Tribology, 2011, 133(3):031701-1-031701-7.
