Numerical Analysis of Laser-Textured Piston-Rings in the Hydrodynamic Lubrication Regime

2012 ◽  
Vol 134 (4) ◽  
Author(s):  
Gonzalo Brito Gadeschi ◽  
Katja Backhaus ◽  
Gunther Knoll
Keyword(s):  
Numerical Analysis ◽  
Friction Coefficient ◽  
Distribution Pattern ◽  
Surface Texture ◽  
Piston Ring ◽  
Hydrodynamic Lubrication ◽  
Piston Rings ◽  
Variable Curvature ◽  
Lubrication Regime ◽  
Optimal Surface

In this work, the performance of barrel-shaped laser-textured piston rings is numerically investigated. The surface texture, parameterized by the dimple density, dimple depth, and dimple distribution pattern, is optimized to minimize the friction coefficient for piston rings of variable curvature. We consider fully textured as well as partially textured piston rings with two different dimple distributions patterns: a central dimple distribution, and a distribution along the piston ring edges. Finally, the sensitivity of the optimal surface parameters to the piston ring curvature is assessed.

A Novel Friction Model Basing on Journal Bearing Theory for Reciprocating Compressor

2013 ◽  
Vol 456 ◽  
pp. 320-323 ◽  
Author(s):  
Le Wang ◽  
Bin Tang ◽  
Yuan Yang Zhao
Keyword(s):  
Friction Coefficient ◽  
Piston Ring ◽  
Sliding Friction ◽  
Journal Bearing ◽  
Hydrodynamic Lubrication ◽  
Dynamic Change ◽  
Friction Model ◽  
Reciprocating Compressor ◽  
Oil Viscosity ◽  
Compressor Performance

The paper presents a comprehensive friction model of reciprocating compressor which is able to evaluate friction losses in moving parts. The model consists of crankshaft, connecting rod and piston all supported by bearings as well as the piston ring/cylinder interface viewed as sliding friction. Hydrodynamic lubrication theory reveals relationship between load and friction coefficient and was demonstrated to be helpful to give insight to the lubrication characteristics of journal bearing. The model gave the composition of friction losses, friction coefficient dynamic change with orbiting angle and effect of oil viscosity on compressor performance. The results showed that the friction losses of piston ring/cylinder interface and the rod big end bearing was most part of the friction losses and it was necessary to choose suitable oil viscosity to reach the optimum compressor performance.

The Statistical Application of a Thermal EHL Theory for Individual Asperity-Asperity Collisions to the Sliding Contact of Rough Surfaces

1975 ◽  
Vol 97 (2) ◽  
pp. 311-318 ◽  
Author(s):  
P. E. Fowles
Keyword(s):  
Friction Coefficient ◽  
Hydrodynamic Lubrication ◽  
Sliding Contact ◽  
Unit Load ◽  
Lubrication Regime ◽  
Statistical Application ◽  
Model Surfaces ◽  
Mixed Lubrication Regime ◽  
Thermal Ehl ◽  
20 Nm

The numerical results of a previously developed thermal EHL theory describing the collisions between idealized asperities are analyzed statistically to obtain macroscopic values of unit load, traction, and friction coefficient for two model surfaces in sliding contact under a range of conditions. It is shown that significant unit loads and tractions can be generated as a result of the microsopic EHL contacts alone. The variation of friction coefficient with load and sliding speed corresponds qualitatively with experiment in the mixed lubrication regime between boundary and hydrodynamic lubrication, but quantitatively the friction coefficients are two to three times too high. The results imply that the lubricant becomes non-Newtonian and/or exhibits a limiting shear strength in virtually all asperity interactions, even those in which the thickness of the intervening lubricant film is maintained in the 20-nm range.

A New Approach to Determine Lubrication Regimes of Piston-Ring Assemblies

1997 ◽  
Vol 119 (4) ◽  
pp. 808-816 ◽  
Author(s):  
Naeim A. Henein ◽  
Shengqiang Huang ◽  
Walter Bryzik
Keyword(s):  
Piston Ring ◽  
Hydrodynamic Lubrication ◽  
Mixed Lubrication ◽  
Spark Ignition Engine ◽  
Frictional Torque ◽  
New Approach ◽  
Lubrication Regimes ◽  
Lubrication Regime ◽  
Mixed Lubrication Regime ◽  
And Shifts

A new approach is developed to determine piston-ring assembly lubrication regimes from the instantaneous frictional torque measured for the whole engine. This is based on the variation of the friction coefficient with the duty parameter in the Stribeck diagram over the mixed and hydrodynamic lubrication regimes. The derived equation determines the lubrication regimes from the slope of the line in the Stribeck diagram. A single cylinder spark ignition engine was instrumented to determine the total instantaneous frictional torque of the engine. Experiments were conducted under different loads at a constant speed. Results show that the regime is mixed lubrication near the top dead center (TDC) and shifts to the hydrodynamic lubrication regime as the piston moves away from TDC. The extent of the mixed lubrication regime depends on engine load and speed.

Computer-Aided Simulation of Piston and Piston Ring Dynamics

1996 ◽  
Vol 118 (4) ◽  
pp. 880-886 ◽  
Author(s):  
G. Knoll ◽  
H. Peeken ◽  
R. Lechtape-Gru¨ter ◽  
J. Lang
Keyword(s):  
Gas Flow ◽  
Piston Ring ◽  
Variable Viscosity ◽  
Hydrodynamic Lubrication ◽  
Combustion Process ◽  
Implicit Time ◽  
Design Parameters ◽  
Piston Rings ◽  
Roughness Effects ◽  
Integration Schemes

A numerical computer simulation program was developed, aiding in finding optimum design parameters in the multibody-system piston, piston-rings, and cylinder with respect to optimum sealing, minimal friction, and minimum noise stimulation (impact impulse). In the simulation of piston secondary movement and piston ring motion, forces arising from the combustion process, subsonic/supersonic gas flow between the combustion chamber and the crank case, inertial forces and forces resulting from the hydrodynamic lubrication between cylinder liner and piston shaft and piston rings and between piston ring flanks and piston grooves are considered. In addition it is possible to account for effects of global, three-dimensional ring deformation as well as local piston deformation, roughness effects in lubricated contacts, and variable viscosity and variable oil supply. The governing differential equations for the pressure as well as the deformation are solved via finite element techniques, while initial value problems are solved by efficient implicit time integration schemes. The application of the developed computer code is presented in examples.

scholarly journals Tribological behavior of co-textured cylinder liner-piston ring during running-in

Friction ◽  
2021 ◽  
Author(s):  
Chenwei Miao ◽  
Zhiwei Guo ◽  
Chengqing Yuan
Keyword(s):  
Friction Coefficient ◽  
Contact Resistance ◽  
Piston Ring ◽  
Tribological Behavior ◽  
Cylinder Liner ◽  
Oil Reservoir ◽  
Piston Rings ◽  
Surface Textures ◽  
Marine Diesel ◽  
Groove Texture

AbstractThe running-in of cylinder liner-piston rings (CLPRs) is the most important process that must be performed before a marine diesel engine can be operated. The quality of running-in directly affects the reliability of a CLPR. The surface texture of a CLPR has been proven to significantly affect its lubrication performance. In this study, the tribological behavior of a CLPR during running-in is investigated. Three types of surface textures are generated on the CLPR via laser processing: dimple texture on piston rings, groove texture on cylinder liners, and co-texture on both sides. Subsequently, a series of tests are performed on a slice tester. A load of 300 N (1.64 MPa) is applied, and two speeds (50 and 100 rpm) are adopted. The CLPR running-in quality is characterized based on three parameters, i.e., the friction coefficient, contact resistance, and wear topography. Experimental results show that, compared with a non-textured surface, the three types of surface textures mentioned above improved the friction performance during running-in. The lubricant supply capacity of the dimple texture on the piston ring, as a mobile oil reservoir, is stronger than that of the groove texture on the cylinder liner serving as a static oil reservoir. By contrast, the wear resistance of the dimple texture, as a movable debris trap on the piston ring, is weaker than that of the groove texture on the cylinder liner, which serves as a static debris trap. It is demonstrated that the co-texture combines the advantages of dimples and groove textures. Compared with non-textured surfaces, the friction coefficient decreased the most at 100 rpm (44.5%), and the contact resistance improved the most at 50 rpm (352.9%). The coupling effect provides the surface with improved running-in quality by optimizing the tribological performance, particularly at the dead center. This study provides guidance for the tribological design and manufacturing of CLPR in marine diesel engines.

scholarly journals Advanced Tribological Characterization of DLC Coatings Produced by Ne-HiPIMS for the Application on the Piston Rings of Internal Combustion Engines

2021 ◽  
Vol 11 (21) ◽  
pp. 10498
Author(s):  
Alireza Vahidi ◽  
Diogo Fonseca ◽  
João Oliveira ◽  
Albano Cavaleiro ◽  
Amílcar Ramalho ◽  
...  
Keyword(s):  
Internal Combustion Engines ◽  
Hydrodynamic Lubrication ◽  
Research Work ◽  
Internal Combustion ◽  
Tribological Performance ◽  
Combustion Engines ◽  
Piston Rings ◽  
Dlc Coatings ◽  
Lubrication Regimes ◽  
Lubrication Regime

Piston rings (PR) are known for almost a quarter of the friction losses in internal combustion engines. This research work aims to improve the tribological performance of PR by a recently developed variant of Diamond-like Carbon (DLC) coatings deposited in a mixture of Ar and Ne plasma atmosphere (Ne-DLC) by high-power impulse magnetron sputtering (HiPIMS). For the benchmark, the widely used Chromium Nitride (CrN) and DLCs deposited in pure Ar plasma atmosphere (Ar-DLC) were used. The tribological tests were performed on a block-on-ring configuration under different lubrication regimes by varying temperatures and sliding speeds. The analysis of the results was performed by Stribeck curves corresponding to each sample. An improvement of the tribological performance was observed for Ne-DLC films by up to 22.8% reduction in COF compared to CrN in the boundary lubrication regime, whereas, for the Ar-DLC film, this reduction was only 9.5%. Moreover, the Ne-DLC films achieved ultralow friction of less than 0.001 during the transition to a hydrodynamic lubrication regime due to better wettability (lower contact angle) and higher surface free energy. Increasing the Ne up to 50% in the discharge gas also leads to an increase of hardness of DLC films from 19 to 24 GPa.

Experimental Investigation of Lubrication Regimes of a Water-Lubricated Bearing in the Propulsion Train of a Marine Vessel

2020 ◽  
Vol 143 (4) ◽  
Author(s):  
Dov Avishai ◽  
Groper Morel
Keyword(s):  
Experimental Investigation ◽  
Friction Coefficient ◽  
Hydrodynamic Lubrication ◽  
Low Cost ◽  
Pollution Prevention ◽  
Elastohydrodynamic Lubrication ◽  
Sliding Bearings ◽  
Naval Vessel ◽  
Lubrication Regimes ◽  
Lubrication Regime

Abstract Sliding bearings, operating in a full hydrodynamic lubrication regime, exhibit a low friction coefficient and extended life. In recent years, with the increase in environmental awareness and pollution prevention, attention is being directed to oil spills, which pollute the environment. This is extremely prominent in ships and submarines whose propeller shafts are typically supported by oil-lubricated sliding bearings. To reduce pollution risk and also to obtain a simpler and low-cost maintenance system, the propeller shafts of numerous modern marine vessels are supported by water-lubricated bearings. An experimental investigation into the lubrication regime of a water-lubricated bearing in the propulsion train of a naval vessel is presented. A test rig was designed and built to allow testing of a scaled water-lubricated composite bearing supporting a naval vessel propeller shaft. Experimental results quantifying the effect of the rotational speed on the operating eccentricity, the friction coefficient, and the bearing’s lubrication regimes are presented. The experimentally obtained results are compared with an elastohydrodynamic lubrication (EHL) model solved by employing comsol multiphysics modeling software, and the differences are addressed. Finally, conclusions that may assist in better understanding the operation profile of the bearing and thus improving the vessel’s operability are presented.

scholarly journals Theoretical Analysis and Experimental Research of Surface Texture Hydrodynamic Lubrication

2020 ◽  
Author(s):  
Dan Li ◽  
Xuefeng YANG ◽  
Wu Yuanbo ◽  
Cheng Jian ◽  
Wang Shouren ◽  
...  
Keyword(s):  
Mathematical Model ◽  
Friction Coefficient ◽  
Theoretical Analysis ◽  
Working Conditions ◽  
Surface Texture ◽  
Hydrodynamic Lubrication ◽  
Experimental Results ◽  
Optimal Selection ◽  
Key Variables ◽  
The Mathematical Model

Abstract This paper established a mathematical model of hydrodynamic lubrication through theoretical analysis, solved the key variables of the mathematical model through simulation and validated the mathematical model using the experimental results. The purpose is to summarize a set of surface texture theory and optimal selection equations for complex working conditions. After comparing the experimental results with the results obtained by the mathematical model, it is found that the two are basically the same in the ranking of the anti-friction properties of different textures, and there is an error of 10%-40% in the friction coefficient value.

scholarly journals Influence of Different Surface Texture Parameters on the Contact Performance of Piston Ring-Sleeve Friction Pair of Hydraulic Cylinders

2021 ◽  
Vol 2021 ◽  
pp. 1-12
Author(s):  
Wen’an Wang ◽  
Zhiqi Liu ◽  
Dongliang Chen ◽  
Zhiming Xie ◽  
Jianli Song
Keyword(s):  
Friction Coefficient ◽  
Surface Texture ◽  
Surface Density ◽  
Friction And Wear ◽  
Piston Ring ◽  
Friction Pair ◽  
Wear Characteristics ◽  
Texture Parameters ◽  
Cylinder Piston ◽  
Friction And Wear Characteristics

The surface texture, a major way to decrease friction and wear of the cylinder-piston ring friction pair, was conducted on cylinder-piston ring friction pair specimen using the orthogonal experimental design method to investigate the effect of different texture parameters (size, depth, shape, and surface density) of the friction and wear characteristics. Through simulation analysis, the texture parameters that affect the friction and wear characteristics are obtained. Using the evaluation method of friction coefficient and mass wear rate, the influence sequence and optimal values of texture parameters that affect friction and wear characteristics are obtained through range analysis. The results show that, after surface texture treatment under mixed lubrication conditions, the friction characteristics of the friction pair have changed and the friction coefficient and friction and wear rate have been significantly reduced. The results show that the triangular texture has a good antifriction effect, the texture depth is deepened, and the surface density and the size increases have a positive effect on the improvement of friction and wear. An ultra-depth microscope was used to observe the wear morphology of the friction and wear tests. The results show that the weakening of the third body wear by the texturing treatment and the maintenance of oil lubrication are the main reasons for reducing friction and wear.

Experimental study on the effect of surface texture on tribological properties of nanodiamond films under water lubrication

2021 ◽  
pp. 135065012110334
Author(s):  
Ying Yan ◽  
Xuelin Lei ◽  
Yun He
Keyword(s):  
Friction Coefficient ◽  
Wear Rate ◽  
Tribological Properties ◽  
Surface Texture ◽  
Diamond Film ◽  
Diamond Films ◽  
Nanocrystalline Diamond ◽  
Water Contact ◽  
Texture Density ◽  
Short Run

The effect of nanoscale surface texture on the frictional and wear performances of nanocrystalline diamond films under water-lubricating conditions were comparatively investigated using a reciprocating ball-on-flat tribometer. Although the untreated nanocrystalline diamond film shows a stable frictional state with an average friction coefficient of 0.26, the subsequent textured films show a beneficial effect on rapidly reducing the friction coefficient, which decreased to a stable value of 0.1. Furthermore, compared with the nanocrystalline diamond coating, the textured films showed a large decreasing rate of the corresponding ball wear rate from 4.16 × 10−3 to 1.15 × 10−3 mm3/N/m. This is due to the fact that the hydrodynamic fluid film composed of water and debris can provide a good lubrication environment, so the entire friction process has reached the state of fluid lubrication. Meanwhile, the surface texture can greatly improve the hydrophilicity of the diamond films, and as the texture density increases, the water contact angle decreases from 94.75° of the nanocrystalline diamond film to 78.5° of the textured films. The proper textured diamond film (NCD90) exhibits superior tribological properties among all tested diamond films, such as short run-in period, low coefficient of friction, and wear rate.

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