Martin Priest
University of Bradford, Engineering and Informatics, Faculty Member
... 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.... 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 ...
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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... 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.
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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... 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.
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Tribology research : from model experiment to industrial problem : a century of efforts in mechanics, materials science and physico-chemistry : proceedings of the 27th Leeds-Lyon Symposium on Tribology held in the Institut National des Sciences Appliquées de Lyon, Lyon, France, 5th-8th September,...more
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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... 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...
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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... 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’
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... 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...
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Research Interests: Engineering and Tribology
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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... 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...
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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... 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...
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The requirement for increased performance, improved fuel economy and reduced emissions is constantly sustaining the demand for research into combustion, fuels and lubricants. Due to the nature of the operation of an engine and the current... more
The requirement for increased performance, improved fuel economy and reduced emissions is constantly sustaining the demand for research into combustion, fuels and lubricants. Due to the nature of the operation of an engine and the current market climate the lubricant not only has to respond to these requirements, but also to changes in engine design, fuelling methods and fuel types,
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Purpose – This paper aims to establish the acid concentration of finely dispersed droplets in hydrocarbon oils. Small quantities of aqueous sulphuric acid (H2SO4) were found to be trapped within hydrocarbon shells, making them... more
Purpose – This paper aims to establish the acid concentration of finely dispersed droplets in hydrocarbon oils. Small quantities of aqueous sulphuric acid (H2SO4) were found to be trapped within hydrocarbon shells, making them inaccessible for concentration evaluation by titration. Design/methodology/approach – Fourier transform infrared spectroscopy (FTIR) used in the attenuated total reflection mode (ATR; FTIR-ATR) was applied to study the reaction products of squalane, C30H62, and an API Group I base oil with various concentrations of aqueous H2SO4. Findings – The absorbance comparison usually used for estimating acid concentrations was found to fail when small quantities of acid are trapped in the reaction product. It was found that the peak shift and changes in absorbance found for various pure aqueous acid concentrations were useful to establish the remaining concentration of the trapped H2SO4. Originality/value – This paper fulfils the identified need to study acid dissociati...