Piston ring performance in two-stroke marine diesel engines: Effect of hydrophobicity and artificial surface texturing on power efficiency

2017 ◽  
Vol 232 (8) ◽  
pp. 940-963 ◽  
Author(s):  
Eleftherios Koukoulopoulos ◽  
Christos I Papadopoulos
Keyword(s):  
Film Thickness ◽  
Power Efficiency ◽  
Piston Ring ◽  
Reynolds Equation ◽  
Surface Texturing ◽  
Design Parameters ◽  
Maximum Value ◽  
Minimum Film Thickness ◽  
Marine Diesel ◽  
Artificial Surface

In the present work, an algorithm for the solution of the Reynolds equation incorporating the Elrod–Adams cavitation model and appropriately modified to account for hydrophobic surfaces has been developed and solved by means of the finite difference method. The algorithm has been utilized to calculate the frictional characteristics of piston rings of a large two-stroke marine diesel engine, and to evaluate their performance, in terms of minimum film thickness, friction force, and power loss over a full-engine cycle, including time-dependent phenomena. For improving frictional behavior, two surface treatments of the piston ring surface have been studied, namely hydrophobicity and artificial surface texturing, which are introduced at appropriate parts of the ring face. Following a parametric analysis, optimal texturing and hydrophobicity design parameters have been identified for operation with maximum value of minimum film thickness and minimum friction losses. The present results demonstrate that substantial performance improvement can be achieved if hydrophobicity or artificial surface texturing is properly introduced at the faces of a piston ring.

Predictive tool for frictional performance of piston ring-pack/liner conjunction

2019 ◽  
Vol 13 (3) ◽  
pp. 5513-5527
Author(s):  
J. W. Tee ◽  
S. H. Hamdan ◽  
W. W. F. Chong
Keyword(s):  
Film Thickness ◽  
Mathematical Models ◽  
Piston Ring ◽  
Published Data ◽  
Predictive Tool ◽  
Frictional Losses ◽  
Fundamental Understanding ◽  
Minimum Film Thickness ◽  
Piston Ring Pack ◽  
Ring Pack

Fundamental understanding of piston ring-pack lubrication is essential in reducing engine friction. This is because a substantial portion of engine frictional losses come from piston-ring assembly. Hence, this study investigates the tribological impact of different piston ring profiles towards engine in-cylinder friction. Mathematical models are derived from Reynolds equation by using Reynolds’ boundary conditions to generate the contact pressure distribution along the complete piston ring-pack/liner conjunction. The predicted minimum film thickness is then used to predict the friction generated between the piston ring-pack and the engine cylinder liner. The engine in-cylinder friction is predicted using Greenwood and Williamson’s rough surface contact model. The model considers both the boundary friction and the viscous friction components. These mathematical models are integrated to simulate the total engine in-cylinder friction originating from the studied piston ring-pack for a complete engine cycle. The predicted minimum film thickness and frictional properties from the current models are shown to correlate reasonably with the published data. Hence, the proposed mathematical approach prepares a simplistic platform in predicting frictional losses of piston ring-pack/liner conjunction, allowing for an improved fundamental understanding of the parasitic losses in an internal combustion engine.

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.

Analysis of Oil Film Thickness on a Piston Ring of Diesel Engine: Effect of Oil Film Temperature

2001 ◽  
Author(s):  
Yasuo Harigaya ◽  
Michiyoshi Suzuki ◽  
Masaaki Takiguchi
Keyword(s):  
Diesel Engine ◽  
Temperature Distribution ◽  
Heat Flow ◽  
Film Thickness ◽  
Piston Ring ◽  
Reynolds Equation ◽  
Energy Equation ◽  
Two Dimensional ◽  
Oil Film ◽  
The Mean

Abstract This paper describes that an analysis of oil film thickness on a piston ring of diesel engine. The oil film thickness has been performed by using Reynolds equation and unsteady, two-dimensional (2-D) energy equation with a heat generated from viscous dissipation. The temperature distribution in the oil film is calculated by using the energy equation and the mean oil film temperature is computed. Then the viscosity of oil film is estimated by using the mean oil film temperature. The effect of oil film temperature on the oil film thickness of a piston ring was examined. This model has been verified with published experimental results. Moreover, the heat flow at ring and liner surfaces was examined. As a result, the oil film thickness could be calculated by using the viscosity estimated from the mean oil film temperature and the calculated value is agreement with the measured values.

Effects of Surface Roughness and Additives in Lubrication: Generalized Reynolds Equation and its Application to Elastohydrodynamic Film

1987 ◽  
Vol 201 (1) ◽  
pp. 1-9 ◽  
Author(s):  
P Sinha ◽  
J S Kennedy ◽  
C M Rodkiewicz ◽  
P Chandra ◽  
R Sharma ◽  
...  
Keyword(s):  
Surface Roughness ◽  
Film Thickness ◽  
Reynolds Equation ◽  
Molecular Size ◽  
One Dimensional ◽  
Theoretical Investigations ◽  
Minimum Film Thickness ◽  
Porous Matrices ◽  
The Mean ◽  
Generalized Reynolds Equation

To study the effects of surface roughness and additives in lubrication, a generalized form of Reynolds equation is derived by taking into account the roughness interaction zones adjacent to the moving rough surfaces as sparsely porous matrices and purely hydrodynamic film of micropolar fluid characterizing the lubricant with additives. A particular, one-dimensional form of this equation is used to study these effects on the elastohydrodynamic (EHD) minimum film thickness at the inlet, between two rough rollers. It is shown that for the low permeability of the roughness zone, the EHD film thickness increases as the mean height of the asperities increases, whereas for the high permeability it decreases. The EHD film thickness is also found to increase with the concentration of the additives and the molecular size of the particles. These results are in conformity at least qualitatively, with various experimental and theoretical investigations, cited in the paper.

Debris Effects on EHL Contact

2000 ◽  
Vol 122 (4) ◽  
pp. 711-720 ◽  
Author(s):  
Young S. Kang ◽  
Farshid Sadeghi ◽  
Xiaolan Ai
Keyword(s):  
Film Thickness ◽  
Reynolds Equation ◽  
Elastohydrodynamic Lubrication ◽  
Force Balance ◽  
Time Dependent ◽  
Elasticity Equations ◽  
Minimum Film Thickness ◽  
Bounding Surfaces ◽  
Force Balance Equation ◽  
Ehl Contact

A model was developed to study the effects of a rigid debris on elastohydrodynamic lubrication of rolling/sliding contacts. In order to achieve the objectives the time dependent Reynolds equation was modified to include the effects of an ellipsoidal shaped debris. The modified time dependent Reynolds and elasticity equations were simultaneously solved to determine the pressure and film thickness in EHL contacts. The debris force balance equation was solved to determine the debris velocity. The model was then used to obtain results for a variety of loads, speeds, and debris sizes. The results indicate that the debris has a significant effect on the pressure distribution and causes a dent on the rolling/sliding bounding surfaces. Depending on the size and location of the debris the pressure generated within the contact can be high enough to plastically deform the bounding surfaces. Debris smaller than the minimum film thickness do not enter the contact and only large and more spherical debris move toward the contact. [S0742-4787(11)00501-7]

The Numerical Analysis on Action Mechanism of Slurry in Free Abrasive Wiresaw Slicing

2007 ◽  
Vol 359-360 ◽  
pp. 455-459
Author(s):  
Pei Qi Ge ◽  
Bo Sang ◽  
Yu Fei Gao
Keyword(s):  
Film Thickness ◽  
Reynolds Equation ◽  
Hydrodynamic Pressure ◽  
Influence Coefficient ◽  
Main Method ◽  
Minimum Film Thickness ◽  
The Mathematical Model ◽  
Slurry Viscosity ◽  
Free Abrasive ◽  
Abrasive Size

Free abrasive wiresaw technology is the main method in slicing monocrystalline silicon wafers. The mathematical model of hydrodynamic action in the process of the free abrasive wiresaw slicing was founded, displacement caused under distributed radial load of every node on the wire is embodimented through self-compliance influence coefficient, which is beneficial to found the film thickness equation. The distributions of hydrodynamic pressure and film thickness in the free abrasive wiresaw slicing process are yielded by using the finite difference numerical methods to solve the two-dimension Reynolds equation. The results show that the minimum film thickness increases with the increase of wire speed, and slurry viscosity, while decreases with the increase of wire bow angle. The film thickness is greater than the average abrasive size so that the abrasives float in the slurry when the size of abrasive is small enough.

Film Thickness and Asperity Load Formulas for Line-Contact Elastohydrodynamic Lubrication With Provision for Surface Roughness

2012 ◽  
Vol 134 (1) ◽  
Author(s):  
M. Masjedi ◽  
M. M. Khonsari
Keyword(s):  
Surface Roughness ◽  
Film Thickness ◽  
Reynolds Equation ◽  
Surface Deformation ◽  
Elastohydrodynamic Lubrication ◽  
Load Ratio ◽  
Material Surface ◽  
Line Contact ◽  
Wide Range ◽  
Minimum Film Thickness

Three formulas are derived for predicting the central and the minimum film thickness as well as the asperity load ratio in line-contact EHL with provision for surface roughness. These expressions are based on the simultaneous solution to the modified Reynolds equation and surface deformation with consideration of elastic, plastic and elasto-plastic deformation of the surface asperities. The formulas cover a wide range of input and they are of the form f(W, U, G, σ¯, V), where the parameters represented are dimensionless load, speed, material, surface roughness and hardness, respectively.

The Simple Model of the Oil Film Thickness between Piston Ring and Cylinder

2010 ◽  
Vol 97-101 ◽  
pp. 1239-1242
Author(s):  
De Liang Liu ◽  
Hui Biao Lu ◽  
C.G. Sun
Keyword(s):  
Film Thickness ◽  
Internal Combustion Engine ◽  
Piston Ring ◽  
Reynolds Equation ◽  
Combustion Engine ◽  
Friction Pair ◽  
Internal Combustion ◽  
Theoretical Research ◽  
Lubricating Oil ◽  
Oil Film

Piston ring-cylinder is one of the most important friction pair of internal combustion engine，the lubricating state between them has decided internal combustion engine lubrication quality. So the theoretical research to the lubricating characteristics of the piston-ring group, especially the calculation of the lubricating oil film thickness is very important. The oil film thickness between piston-ring and cylinder is studied by calculation method. The calculation program is developed with average Reynolds equation taken the surface topography, viscosity-temperature effect, viscosity-pressure effect, extrusion effect and other factors into account. The position of oil outlet point is preinstalled, the full lubrication is assumed, and the Reynolds equation is solved by full pivot element gausses elimination approach, so the iterative course and calculation workload are reduced, and a great lot of the calculating time is saved, the oil film thickness of full period can be more accurately predicted by the ordinary PC within 30 minutes, which can supply quick effective evidence for next calculation and analysis.

Investigation of the Failure of Heavily Loaded Journal Bearings

1994 ◽  
Vol 208 (3) ◽  
pp. 167-171
Author(s):  
D Ashman
Keyword(s):  
Film Thickness ◽  
Reynolds Equation ◽  
Journal Bearing ◽  
Elastohydrodynamic Lubrication ◽  
Failure Criteria ◽  
Operating Conditions ◽  
Minimum Film Thickness ◽  
Hydrodynamic Solution ◽  
Metrological Study ◽  
Theoretical Minimum

This paper gives details of a combined theoretical and experimental investigation of a plain journal bearing under heavily loaded conditions together with a metrological study of the bearing geometry. It was found that under high loading conditions a simplified analytical expression relating the Sommerfeld number to the non-dimensional minimum film thickness, using a hydrodynamic solution of the isoviscous form of the Reynolds equation, could be developed. An alternative theoretical solution based on elastohydrodynamic lubrication was also considered. In addition, experimental work determined a variety of operating conditions that produced metal-to-metal contact. These operating conditions were then compared with the theoretical minimum film thickness calculations and bearing manufacturing data. This process was used to determine combined failure criteria based on operating conditions and machining capability.

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