The Possible Role of Surface Tension in the Reduction of Top Ring Drag 932781
In a small (4.5 KW) diesel engine, Laser Induced Fluorescence (LIF) has been used to produce detailed oil film thickness measurements around the top piston ring and liner near midstroke. The flow is “Newtonian” under the ring in the sense that using a high shear rate viscosity at the liner temperature is appropriate. The geometry corresponds everywhere to that required for a valid Reynolds approximation. Classical boundary conditions are not applicable for the high strain rates (106-107 s-1) under the piston rings of typical modem engines. A new boundary condition is developed to explain the data. The exit surface shear stress is shown to scale with a Marangoni-like (surface tension gradient) effect. By increasing surface tension, it is possible to make substantial reductions in friction for a fixed high shear viscosity.
Citation: Hoult, D. and Azzola, J., "The Possible Role of Surface Tension in the Reduction of Top Ring Drag," SAE Technical Paper 932781, 1993, https://doi.org/10.4271/932781. Download Citation
Author(s):
David P. Hoult, James H. Azzola
Affiliated:
Massachusetts Institute of Technology, Westinghouse Science and Technology
Pages: 13
Event:
International Fuels & Lubricants Meeting & Exposition
ISSN:
0148-7191
e-ISSN:
2688-3627
Also in:
Tribological Insights and Performance Characteristics of Modern Engine Lubricants-SP-0996, SAE 1993 Transactions: Journal of Fuels & Lubricants-V102-4
Related Topics:
Diesel / compression ignition engines
Pistons
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