... WANG, GF DARGUSH, A. SOOM, MM GRIGORIEV 519 History-Dependent Synchronization in the Burridge... more ... WANG, GF DARGUSH, A. SOOM, MM GRIGORIEV 519 History-Dependent Synchronization in the Burridge-Knopoff Model J. SZKUTNIK, B. KAWECKA-MAGIERA, K. KUtAKOWSKI 529 Dynamic Friction Evolution during Transient Sliding G. CHEVALLIER, F. MACEWKO, F ...
These engines vary widely in size and speed, as well as in design and construction, depending on ... more These engines vary widely in size and speed, as well as in design and construction, depending on their intended use. Fuels range from natural gas to heavy residual fuel oil, with many classes of gaseous and liquified fuels in between. The lubricating oil requirements for diesel, dual fuel and gas engines are quite different from the gasoline engine, and actually vary widely among themselves. These differences of viscosity, pour point, additives, flash and fire points, etc., and their influence upon engine performance and wear are evaluated.
The increase availability of operational data from the fleets of cars in the field offers opportu... more The increase availability of operational data from the fleets of cars in the field offers opportunities to deploy machine learning to identify patterns of driver behaviour. This provides contextual intelligence insight that can be used to design strategies for online optimisation of the vehicle performance, including compliance with stringent legislation. This paper illustrates this approach with a case study for a Diesel Particulate Filter, where machine learning deployed to real world automotive data is used in conjunction with a reliability inspired performance modelling paradigm to design a strategy to enhance operational performance based on predictive driver behaviour. The model-in-the-loop simulation of the proposed strategy on a fleet of vehicles showed significant improvement compared to the base strategy, demonstrating the value of the approach.
The tribological performance of the piston assembly of an automotive engine is highly influenced ... more 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 m...
PolyEtherKetone (PEK) is a suitable material for tribological systems which specifically require ... more PolyEtherKetone (PEK) is a suitable material for tribological systems which specifically require the properties of high chemical resistance, low component weight, seizure resistance under starved lubrication conditions and operation at higher temperatures than many other engineering polymers can survive. PEK is used with a liquid lubricant at high temperatures and velocities to reduce friction and also to control unstable friction and wear, particularly in the region of the material's glass transition temperature, Tg. Intermittent and marginal lubrication using representative high temperature synthetic lubricants was applied to high speed, high temperature PEK/steel sliding contacts to determine the effectiveness of lubrication under these conditions. Variations in the stability of the thin lubricant films were observed, particularly under different load conditions. Under low load conditions, the lubricant polarity and the related ability to form a film in the contact was important. Under high load conditions, the thermal stability of the lubricant became more important in retaining stability in the friction and wear mechanisms. Whilst not ideal practice, marginal lubrication of PEK-steel sliding contacts can be achieved by selection of an appropriate lubricant, even in the glass transition region of PEK.
I/c engines will be part of ‘daily life’ to 2050, as sole or hybrid prime movers. The targets are... more I/c engines will be part of ‘daily life’ to 2050, as sole or hybrid prime movers. The targets are 50% reduced emissions and 100% increased fuel efficiency. Many engineering disciplines contribute to ‘light weighting’, increased thermodynamic efficiency, reduced Cd values and more efficient tyres. Internal engine friction from in-bore components is a major energy loss from ‘fuel tank’ to ‘road wheel’
Proceedings of the Institution of Mechanical Engineers, Part J: Journal of Engineering Tribology, 2016
Advanced engineering polymers of the polyaryletherketone (PAEK) family with carbon fibre reinforc... more Advanced engineering polymers of the polyaryletherketone (PAEK) family with carbon fibre reinforcement are finding application in engineering systems as tribological bearing surfaces under severe operating conditions that cyclically move the polymer into and beyond the glass transition temperature region. To support such an application, the friction in high-speed and low-load PAEK-steel sliding contacts was investigated both unlubricated and lubricated with a trinonyl trimellitate ester, a base fluid for high temperature industrial lubricants. Four polymers in the PAEK family, PEEK, PEK, PEKEKK and PEKK, with 30 wt% of carbon fibre whiskers were tested against an AISI 4140 steel disc. When unlubricated, low friction depended upon the formation of a PAEK transfer film on the steel disc and when this became unstable in the glass transition region the friction increased to much higher levels with associated polymer surface damage. Frictional heating due to the high sliding speed domina...
In order to explore the change rule of physiological indexes during the aging process of the liqu... more In order to explore the change rule of physiological indexes during the aging process of the liquid spawn of Auricularia auricula, this test chooses three species of Auricularia auricula(Hei29, Heiweibanjin and Heiweidanpian), which treasured the activities of antioxidant enzymes, antioxidant substances, membrane peroxidation degree and reactive oxygen concentration during different mycelia age. The conclusion showed that: at the same mycelial age, the vitality of Heiweidanpian was the strongest, Hei29 followed, and Heiweibanjin was the weakest; with the increase of mycelia age, Catalase (CAT) activity, Ascorbic Acid(ASA) content, Malondialdehyde (MDA) content and O 2-production rate of the three kinds of Auricularia auricula increased continuously. Among them, ASA content, MDA content and O 2-production rate increased significantly, while Superoxide Dismutase (SOD) activity decreased significantly; although the Proline (Pro) content and electrical conductivity of the three kinds of Auricularia auricula showed different trends, which decreased significantly at 14 to 16d and increased significantly at 8 to 10d, respectively, and H2O2 content increased significantly at 12 to 16d. It can be seen that SOD activity, CAT activity, ASA content, MDA content and O 2production rate have significant regular changes during the aging process of the liquid spawn of Auricularia auricula. The quantitative analysis found that when the MDA content is 1.42~1.72 μmol•g-1 , the H2O2 content is 3.4~4.3 μmol•g-1 or the O 2-production rate is 9.5~12.1 μmol•g-1 •min-1 , it can be considered Auricularia auricula just started to age or the aging degree is relatively low.
The presence of lubricant droplets in the gas that flows through the piston assembly and crankcas... more 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, visc...
Proceedings of the Institution of Mechanical Engineers, Part C: Journal of Mechanical Engineering Science, 2000
Mathematical models of piston ring dynamics and lubrication are sensitive to the boundary conditi... more Mathematical models of piston ring dynamics and lubrication are sensitive to the boundary conditions adopted to describe the cavitation occurring in the diverging outlet region of the lubricant film between the piston ring and cylinder wall. In this paper, such sensitivity is investigated by applying different models of gaseous cavitation, flow separation and fluid film reformation to the analysis of a single compression ring from a diesel engine. Significant differences are predicted in hydrodynamic pressure profiles, lubricant film boundaries, lubricant film thickness, oil flow and friction. Such indications of substantial differences in piston ring operating characteristics associated with the distinct cavitation boundary conditions considered highlights the need for further research in this field. However, the lack of detailed experimental data to validate the predictive models suggests that future progress must be based upon combined theoretical and experimental approaches to t...
A laser induced fluorescence system has been developed to visualise the oil film thickness betwee... more A laser induced fluorescence system has been developed to visualise the oil film thickness between the piston ring and cylinder wall of a fired gasoline engine via a small optical window mounted in the cylinder wall. A fluorescent dye was added to the lubricant in the sump to allow the lubricant to fluoresce when absorbing laser radiation. The concentration of the dye did not disturb the lubricant chemistry or its performance. Degraded engine oil samples were used to investigate the influence of lubricant quality on ring pack lubricant film thickness measurements. The results show significant differences in the lubricant film thickness profiles for the ring pack when the lubricant degrades which will affect ring pack friction and ultimately fuel economy.
... WANG, GF DARGUSH, A. SOOM, MM GRIGORIEV 519 History-Dependent Synchronization in the Burridge... more ... WANG, GF DARGUSH, A. SOOM, MM GRIGORIEV 519 History-Dependent Synchronization in the Burridge-Knopoff Model J. SZKUTNIK, B. KAWECKA-MAGIERA, K. KUtAKOWSKI 529 Dynamic Friction Evolution during Transient Sliding G. CHEVALLIER, F. MACEWKO, F ...
These engines vary widely in size and speed, as well as in design and construction, depending on ... more These engines vary widely in size and speed, as well as in design and construction, depending on their intended use. Fuels range from natural gas to heavy residual fuel oil, with many classes of gaseous and liquified fuels in between. The lubricating oil requirements for diesel, dual fuel and gas engines are quite different from the gasoline engine, and actually vary widely among themselves. These differences of viscosity, pour point, additives, flash and fire points, etc., and their influence upon engine performance and wear are evaluated.
The increase availability of operational data from the fleets of cars in the field offers opportu... more The increase availability of operational data from the fleets of cars in the field offers opportunities to deploy machine learning to identify patterns of driver behaviour. This provides contextual intelligence insight that can be used to design strategies for online optimisation of the vehicle performance, including compliance with stringent legislation. This paper illustrates this approach with a case study for a Diesel Particulate Filter, where machine learning deployed to real world automotive data is used in conjunction with a reliability inspired performance modelling paradigm to design a strategy to enhance operational performance based on predictive driver behaviour. The model-in-the-loop simulation of the proposed strategy on a fleet of vehicles showed significant improvement compared to the base strategy, demonstrating the value of the approach.
The tribological performance of the piston assembly of an automotive engine is highly influenced ... more 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 m...
PolyEtherKetone (PEK) is a suitable material for tribological systems which specifically require ... more PolyEtherKetone (PEK) is a suitable material for tribological systems which specifically require the properties of high chemical resistance, low component weight, seizure resistance under starved lubrication conditions and operation at higher temperatures than many other engineering polymers can survive. PEK is used with a liquid lubricant at high temperatures and velocities to reduce friction and also to control unstable friction and wear, particularly in the region of the material's glass transition temperature, Tg. Intermittent and marginal lubrication using representative high temperature synthetic lubricants was applied to high speed, high temperature PEK/steel sliding contacts to determine the effectiveness of lubrication under these conditions. Variations in the stability of the thin lubricant films were observed, particularly under different load conditions. Under low load conditions, the lubricant polarity and the related ability to form a film in the contact was important. Under high load conditions, the thermal stability of the lubricant became more important in retaining stability in the friction and wear mechanisms. Whilst not ideal practice, marginal lubrication of PEK-steel sliding contacts can be achieved by selection of an appropriate lubricant, even in the glass transition region of PEK.
I/c engines will be part of ‘daily life’ to 2050, as sole or hybrid prime movers. The targets are... more I/c engines will be part of ‘daily life’ to 2050, as sole or hybrid prime movers. The targets are 50% reduced emissions and 100% increased fuel efficiency. Many engineering disciplines contribute to ‘light weighting’, increased thermodynamic efficiency, reduced Cd values and more efficient tyres. Internal engine friction from in-bore components is a major energy loss from ‘fuel tank’ to ‘road wheel’
Proceedings of the Institution of Mechanical Engineers, Part J: Journal of Engineering Tribology, 2016
Advanced engineering polymers of the polyaryletherketone (PAEK) family with carbon fibre reinforc... more Advanced engineering polymers of the polyaryletherketone (PAEK) family with carbon fibre reinforcement are finding application in engineering systems as tribological bearing surfaces under severe operating conditions that cyclically move the polymer into and beyond the glass transition temperature region. To support such an application, the friction in high-speed and low-load PAEK-steel sliding contacts was investigated both unlubricated and lubricated with a trinonyl trimellitate ester, a base fluid for high temperature industrial lubricants. Four polymers in the PAEK family, PEEK, PEK, PEKEKK and PEKK, with 30 wt% of carbon fibre whiskers were tested against an AISI 4140 steel disc. When unlubricated, low friction depended upon the formation of a PAEK transfer film on the steel disc and when this became unstable in the glass transition region the friction increased to much higher levels with associated polymer surface damage. Frictional heating due to the high sliding speed domina...
In order to explore the change rule of physiological indexes during the aging process of the liqu... more In order to explore the change rule of physiological indexes during the aging process of the liquid spawn of Auricularia auricula, this test chooses three species of Auricularia auricula(Hei29, Heiweibanjin and Heiweidanpian), which treasured the activities of antioxidant enzymes, antioxidant substances, membrane peroxidation degree and reactive oxygen concentration during different mycelia age. The conclusion showed that: at the same mycelial age, the vitality of Heiweidanpian was the strongest, Hei29 followed, and Heiweibanjin was the weakest; with the increase of mycelia age, Catalase (CAT) activity, Ascorbic Acid(ASA) content, Malondialdehyde (MDA) content and O 2-production rate of the three kinds of Auricularia auricula increased continuously. Among them, ASA content, MDA content and O 2-production rate increased significantly, while Superoxide Dismutase (SOD) activity decreased significantly; although the Proline (Pro) content and electrical conductivity of the three kinds of Auricularia auricula showed different trends, which decreased significantly at 14 to 16d and increased significantly at 8 to 10d, respectively, and H2O2 content increased significantly at 12 to 16d. It can be seen that SOD activity, CAT activity, ASA content, MDA content and O 2production rate have significant regular changes during the aging process of the liquid spawn of Auricularia auricula. The quantitative analysis found that when the MDA content is 1.42~1.72 μmol•g-1 , the H2O2 content is 3.4~4.3 μmol•g-1 or the O 2-production rate is 9.5~12.1 μmol•g-1 •min-1 , it can be considered Auricularia auricula just started to age or the aging degree is relatively low.
The presence of lubricant droplets in the gas that flows through the piston assembly and crankcas... more 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, visc...
Proceedings of the Institution of Mechanical Engineers, Part C: Journal of Mechanical Engineering Science, 2000
Mathematical models of piston ring dynamics and lubrication are sensitive to the boundary conditi... more Mathematical models of piston ring dynamics and lubrication are sensitive to the boundary conditions adopted to describe the cavitation occurring in the diverging outlet region of the lubricant film between the piston ring and cylinder wall. In this paper, such sensitivity is investigated by applying different models of gaseous cavitation, flow separation and fluid film reformation to the analysis of a single compression ring from a diesel engine. Significant differences are predicted in hydrodynamic pressure profiles, lubricant film boundaries, lubricant film thickness, oil flow and friction. Such indications of substantial differences in piston ring operating characteristics associated with the distinct cavitation boundary conditions considered highlights the need for further research in this field. However, the lack of detailed experimental data to validate the predictive models suggests that future progress must be based upon combined theoretical and experimental approaches to t...
A laser induced fluorescence system has been developed to visualise the oil film thickness betwee... more A laser induced fluorescence system has been developed to visualise the oil film thickness between the piston ring and cylinder wall of a fired gasoline engine via a small optical window mounted in the cylinder wall. A fluorescent dye was added to the lubricant in the sump to allow the lubricant to fluoresce when absorbing laser radiation. The concentration of the dye did not disturb the lubricant chemistry or its performance. Degraded engine oil samples were used to investigate the influence of lubricant quality on ring pack lubricant film thickness measurements. The results show significant differences in the lubricant film thickness profiles for the ring pack when the lubricant degrades which will affect ring pack friction and ultimately fuel economy.
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Papers by Martin Priest