Numerical Simulation of Piston Ring in Mixed Lubrication—A Nonaxisymmetrical Analysis

1994 ◽  
Vol 116 (3) ◽  
pp. 470-478 ◽  
Author(s):  
Yuanzhong Hu ◽  
Herbert S. Cheng ◽  
Takayuki Arai ◽  
Yoichi Kobayashi ◽  
Shunichi Aoyama
Keyword(s):  
Film Thickness ◽  
Load Distribution ◽  
Piston Ring ◽  
Mixed Lubrication ◽  
Contact Load ◽  
Asperity Contact ◽  
Static Distortion ◽  
Piston Ring Lubrication ◽  
Cylinder Bore

The assumption of axisymmetry, employed by most of studies on piston ring lubrication, probably gives a too idealistic model for the real situation. A theoretical model for a nonaxisymmetrical analysis of piston ring lubrication has been established in the present study. When a piston ring with an arbitrary free shape is fitted into the cylinder bore, the determination of ring deflection and contact load has been modeled mathematically as a Linear Complementary Problem (LCP). By combining LCP solution with lubrication analysis, the film thickness and contact load distribution over the circumference are obtained, leading to a more realistic simulation for piston ring lubrication. The friction force between piston ring and cylinder bore is predicted by the mixed lubrication model including the effects of surface roughness and asperity contact. The static distortion of cylinder bore, gas pressure variation, and lubricant starvation are also considered in the simulation. Results show that the contact pattern and film thickness between piston ring and cylinder bore are not exactly axisymmetrical. The main reason for the nonuniform contact is the asymmetry of ring elasticity, the static distortion and dynamic load created by the secondary movement of piston skirt.

Analysis of Tribological Performance of Piston Ring Lubrication

2011 ◽  
Author(s):  
Yibin Guo ◽  
Wanyou Li ◽  
Dequan Zou ◽  
Xiqun Lu ◽  
Tao He
Keyword(s):  
Film Thickness ◽  
Friction Force ◽  
Power Loss ◽  
Piston Ring ◽  
Design Parameters ◽  
Oil Film ◽  
Starved Lubrication ◽  
Piston Ring Lubrication ◽  
Cylinder Bore ◽  
Lubrication Conditions

In this paper a mixed lubrication model considering lubricant supply conditions on cylinder bore has been developed for the piston ring lubrication. The numerical procedures of both fully flooded and starved lubrication were included in the model. The lubrication equations and boundary conditions at the end of strokes were discussed in detail. The effects of piston ring design parameters, such as ring face profile and ring tension, on oil film thickness, friction force and power loss under fully flooded and starved lubrication conditions due to available lubricant supply on cylinder bore were studied. The simulation results show that the oil available in the inlet region of the oil film is important to the piston ring friction power loss. With different ring face crown heights and tensions, the changes of oil film thickness and friction force were apparent under fully flooded lubrication, but almost no changes were found under starved lubrication except at the end of a stroke. In addition, the oil film thickness and friction force were affected evidently by the ring face profile offsets under both fully flooded and starved lubrication conditions, and the offset towards the combustion chamber made a large contribution to forming thicker oil film during the expansion stroke. So under different lubricant supply conditions on the cylinder bore, the ring profile and tension need to be adjusted to reduce the friction and power loss. Moreover, the effects of lubricant viscosity, surface composite roughness, and engine operating speed on friction force and power loss were also discussed.

Piston Ring-Cylinder Bore Friction Modeling in Mixed Lubrication Regime: Part I—Analytical Results

1999 ◽  
Vol 123 (1) ◽  
pp. 211-218 ◽  
Author(s):  
Ozgen Akalin ◽  
Golam M. Newaz
Keyword(s):  
Boundary Conditions ◽  
Friction Force ◽  
Piston Ring ◽  
Cylinder Liner ◽  
Surface Flow ◽  
Mixed Lubrication ◽  
Asperity Contact ◽  
Friction Modeling ◽  
Crank Angle ◽  
Cylinder Bore

An axi-symmetric, hydrodynamic, mixed lubrication model has been developed using the averaged Reynolds equation and asperity contact approach in order to simulate frictional performance of piston ring and cylinder liner contact. The friction force between piston ring and cylinder bore is predicted considering rupture location, surface flow factors, surface roughness and metal-to-metal contact loading. A fully flooded inlet boundary condition and Reynolds boundary conditions for cavitation outlet zone are assumed. Reynolds boundary conditions have been modified for non-cavitation zones. The pressure distribution along the ring thickness and the lubricant film thickness are determined for each crank angle degree. Predicted friction force is presented for the first compression ring of a typical diesel engine as a function of crank angle position.

Two-dimensional lubrication study of the piston ring pack

1998 ◽  
Vol 212 (3) ◽  
pp. 215-220 ◽  
Author(s):  
K Liu ◽  
Y. B. Xie ◽  
C. L. Gui
Keyword(s):  
Film Thickness ◽  
Piston Ring ◽  
Cylinder Wall ◽  
Asperity Contact ◽  
Two Dimensional ◽  
Oil Film ◽  
Secondary Motion ◽  
Piston Ring Pack ◽  
Ring Pack ◽  
Piston Ring Lubrication

Based on the two-dimensional average flow model and asperity contact model, a theoretical model for the non-axisymmetrical analysis of piston ring lubrication has been suggested in this paper. The two-dimensional distribution of oil-film thickness between the piston rings and cylinder wall is obtained. Results show that the oil-film thickness along the circumference is non-uniform. Starvation is also considered in the model. The effect of secondary motion of piston assemblies on the lubrication property of the piston ring pack has also been studied.

Analysis of Piston Ring Lubrication with Different Lubricant Supply

2011 ◽  
Vol 199-200 ◽  
pp. 700-706 ◽  
Author(s):  
Yi Bin Guo ◽  
Xi Qun Lu ◽  
De Quan Zou ◽  
Tao He ◽  
Wan You Li ◽  
...  
Keyword(s):  
Power Loss ◽  
Piston Ring ◽  
Contact Friction ◽  
Asperity Contact ◽  
Oil Supply ◽  
Simulation Results ◽  
Piston Ring Lubrication ◽  
Cylinder Bore ◽  
Lubricant Viscosity ◽  
Lubrication Models

In this paper fully flooded and starved lubrication models considering surface roughness are developed for the piston ring and cylinder bore lubrication. The effect of oil available in the inlet region of a top ring is studied by comparing predicted oil film thickness, asperity contact friction and power loss under different oil supply conditions. The simulation results show that the proper oil supply is important in controlling the piston ring frictional power loss. The influences of lubricant viscosity and composite roughness on frictional power loss of piston ring are also discussed.

Film Thickness and Friction Measurement of Piston Ring Cylinder Liner Contact With Corresponding Modeling Including Mixed Lubrication

2004 ◽  
Author(s):  
Nathan W. Bolander ◽  
Brian D. Steenwyk ◽  
Ashwin Kumar ◽  
Farshid Sadeghi
Keyword(s):  
Film Thickness ◽  
Analytical Model ◽  
Piston Ring ◽  
Cylinder Liner ◽  
Mixed Lubrication ◽  
Lubricant Film ◽  
Asperity Contact ◽  
Lubricant Film Thickness ◽  
Lubrication Regimes ◽  
Experimental Apparatus

An experimental apparatus and an analytical model have been developed to investigate and determine the lubrication condition and frictional losses at the interface between a piston ring and cylinder liner. The experimental apparatus features twin fiber optic displacement sensors to accurately measure the lubricant film thickness and a tri-axial piezoelectric force transducer to simultaneously measure frictional force. An analytical mixed lubrication model featuring Elrod cavitation and a stochastic/deterministic approach for asperity contact was used to investigate the effects of boundary and mixed lubrication conditions at the ends-of-stroke. A comparison between experimental and analytical results indicated that they are in good agreement. The results illustrate the transition through all of the different lubrication regimes (i.e. boundary, mixed and hydrodynamic lubrication) the piston ring and liner experience during a stroke. The twin displacement sensor arrangement is capable of producing accurate, repeatable measurements of lubricant film thickness that are in agreement with the analytical predictions. The analytical model developed for this study can capture the different lubrication regimes that the piston ring and liner experience.

A Mixed-Lubrication Study of Journal Bearing Conformal Contacts

1997 ◽  
Vol 119 (3) ◽  
pp. 456-461 ◽  
Author(s):  
Qian (Jane) Wang ◽  
Fanghui Shi ◽  
Si C. Lee
Keyword(s):  
Film Thickness ◽  
Contact Pressure ◽  
Contact Area ◽  
Numerical Solutions ◽  
Mixed Lubrication ◽  
Lubricant Film ◽  
Operating Conditions ◽  
Asperity Contact ◽  
Lubricant Film Thickness ◽  
Asperity Contacts

Numerical analyses of finite journal bearings operating with large eccentricity ratios were conducted to better understand the mixed lubrication phenomena in conformal contacts. The average Reynolds equation derived by Patir and Cheng was utilized in the lubrication analysis. The influence function, calculated numerically using the finite element method, was employed to compute the bearing deformation. The effects of bearing surface roughness were incorporated in the present analysis for the calculations of the asperity contact pressure and the asperity contact area. The numerical solutions of the hydrodynamic and asperity contact pressures, lubricant film thickness, and asperity contact area were evaluated based on a simulated bearing-journal geometry. The calculations revealed that the asperity contact pressure may vary significantly along both the width and the circumferential directions. It was also shown that the asperity contacts and the lubricant film thickness were strongly dependent on the bearing width, asperity orientation, and operating conditions.

Frictional Characteristics of IF-WS2 Nanoparticles in Simulated Engine Conditions

2009 ◽  
Author(s):  
Burak Gullac ◽  
Ozgen Akalin
Keyword(s):  
Piston Ring ◽  
Normal Load ◽  
Mineral Oil ◽  
Test System ◽  
Mixed Lubrication ◽  
Bench Test ◽  
Inorganic Fullerene ◽  
Lubrication Regime ◽  
Mixed Lubrication Regime ◽  
Cylinder Bore

The effect of inorganic fullerene-like (IF) WS2 nanoparticles added to mineral oil which has a potential to reduce engine friction was investigated using a reciprocating piston ring - cylinder bore bench test system. The test system simulates actual engine conditions controlling oil temperature, speed, and normal load. Frictional characteristics of various IF-WS2 nanoparticle concentrations in mineral oil were experimentally analyzed. After a certain period of running in mixed lubrication regime, a significant reduction in friction coefficient was observed when the IF-WS2 formulated oil was used. This reduction remains to some extent with the reference mineral oil even after solvent cleaning. The results show that a thin tribofilm gradually forms on the piston ring and the cylinder bore surfaces that reduce the coefficient of friction in mixed lubrication regime. The effects of lubrication regime, load, speed, temperature and surface roughness on tribofilm formation were also discussed.

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