Modeling Engine Oil Vaporization and Transport of the Oil Vapor in the Piston Ring Pack of Internal Combustion Engines

Cho, Yeunwoo; Tian, Tian

doi:10.4271/2004-01-2912

Cited by 6 publications

(3 citation statements)

References 12 publications

(9 reference statements)

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“…The present work has shown that combustion-driven gas flows within the piston crevices can have profound effects on the top land oil film thickness distribution. It has also demonstrated that the multidimensional shock-capturing algorithm described in sections 2 and 3 is successful when applied to nonlinear PDEs of the form of equation (3).…”

Section: Discussionmentioning

confidence: 98%

“…A distillation curve presented in reference [3] shows that, for some lubricants, the lowest-molecularweight hydrocarbons in the base stock have a lower boiling temperature than 349 uC, and hence can easily be vaporized at such a temperature. In addition to expediting vaporization, high temperatures typically yield an increase in the lubricant's oxidation rate, which is tied to deposit formation.…”

Section: Introductionmentioning

confidence: 99%

“…The top land is a harsh environment for an engine lubricant; reference [2] reports a top land temperature of 349 uC (of course, the top land oil temperature would generally be non-uniform and unsteady). A distillation curve presented in reference [3] shows that, for some lubricants, the lowest-molecularweight hydrocarbons in the base stock have a lower boiling temperature than 349 uC, and hence can easily be vaporized at such a temperature. In addition to expediting vaporization, high tempera-*Corresponding author: email: sean.mcgrogan@gmail.com tures typically yield an increase in the lubricant's oxidation rate, which is tied to deposit formation.…”

Section: Introductionmentioning

confidence: 99%

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Numerical simulation of combustion-driven oil transport on the top land of an internal combustion engine piston

McGrogan

Tian

2010

International Journal of Engine Research

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A mathematical model of a lubricant film attached to the top land of an internal combustion engine piston was formulated. Multidimensional oil transport induced by gas flows within the top land crevice was included in the model, with the intention of predicting the effects of such gas flows on top land carbon deposits. A finite-volume, shock-capturing simulation of the film's free surface was created, and its accuracy verified. Preliminary results were generated using crevice gas flow data taken from a separate computational fluid dynamics (CFD) simulation of a modern diesel engine's combustion process.It was found that combustion-driven gas flows within the top land crevice can have a profound effect on the top land oil film thickness distribution. A fundamental lubricant transport mechanism arising from an interaction between the effects of the engine's reciprocating inertia and those of the gas flow-induced shear forces was discovered. For the engine studied in the present work, the mechanism severely reduced the amount of lubricant in some regions of the top land. An engine designer's clever usage of this mechanism could potentially reduce both oil consumption and top land carbon deposits.

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Section: Discussionmentioning

confidence: 98%

Section: Introductionmentioning

confidence: 99%

Section: Introductionmentioning

confidence: 99%

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Numerical simulation of combustion-driven oil transport on the top land of an internal combustion engine piston

McGrogan

Tian

2010

International Journal of Engine Research

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Simulating the Misting of Lubricant in the Piston Assembly of an Automotive Gasoline Engine: The Effect of Viscosity Modifiers and Other Key Lubricant Components

2022

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The presence of lubricant droplets in the gas that flows through the piston assembly and crankcase of an internal combustion engine (generically termed oil misting) has important implications for performance, particularly lubricant supply to the upper piston assembly, oil consumption and lubricant degradation. A significant source of these droplets is thought to be oil shearing and blow-through by blow-by gas flows in the piston assembly. An experimental rig was developed to simulate the high velocity gas and lubricant film interactions at a top piston ring gap where the flow conditions are most severe. Flows of lubricant droplets were produced and characterised in terms of the proportion of the oil flow that formed droplets in the gas flow and the size distribution of the droplets produced. Considering various aspects of a commercial automotive crankcase formulation, the effect of lubricant viscosity was found to be particularly important. Of the lubricant additives evaluated, viscosity modifiers were found to have the greatest effect on the tendency to form droplets: Detailed study on a range of viscosity modifiers identified that the influence of their molecular architectures on viscoelasticity was the key mechanism.

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The Flow of Lubricant as a Mist in the Piston Assembly and Crankcase of a Fired Gasoline Engine

2022

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The tribological performance of the piston assembly of an automotive engine is highly influenced by the complex flow mechanisms that supply lubricant to the upper piston rings. As well as affecting friction and wear, the oil consumption and emissions of the engine are strongly influenced by these mechanisms. There is a significant body of work that seeks to model these flows effectively. However, these models are not able to fully describe the flow of lubricant through the piston assembly. Some experimental studies indicate that droplets of lubricant carried in the gas flows through the piston assembly may account for some of this. This work describes an investigation into the nature of lubricant misting in a fired gasoline engine. Previous work in a laboratory simulator showed that the tendency of a lubricant to form mist is dependent on the viscosity of the lubricant and the type and concentration of viscosity modifier. The higher surface area-to-volume ratio of the lubricant if more droplets are formed or if the droplets are smaller is hypothesised to increase the degradation rate of the lubricant. The key work in the investigation was to measure the size distribution of the droplets in the crankcase of a fired gasoline engine. Droplets were extracted from the crankcase and passed through a laser diffraction particle sizer. Three characteristic droplet size ranges were observed: Spray sized (250–1000 μm); Major mist (30–250 μm); and Minor mist (0.1–30 μm). Higher base oil viscosity tended to reduce the proportion of mist-sized droplets. The viscoelasticity contributed by a polymeric viscosity modifier reduced the proportion of mist droplets, especially at high load.

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Modeling Engine Oil Vaporization and Transport of the Oil Vapor in the Piston Ring Pack of Internal Combustion Engines

Cited by 6 publications

References 12 publications

Numerical simulation of combustion-driven oil transport on the top land of an internal combustion engine piston

Numerical simulation of combustion-driven oil transport on the top land of an internal combustion engine piston

Simulating the Misting of Lubricant in the Piston Assembly of an Automotive Gasoline Engine: The Effect of Viscosity Modifiers and Other Key Lubricant Components

The Flow of Lubricant as a Mist in the Piston Assembly and Crankcase of a Fired Gasoline Engine

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