Boundary friction characterisation of a used cylinder liner subject to fired engine conditions and surface deposition
journal contributionposted on 12.11.2018 by Rickie Bewsher, Michael Leighton, Mahdi Mohammadpour, Homer Rahnejat, Gunter Offner, O. Knaus
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In cylinder friction contributes as a primary source of parasitic dissipations in IC engines. For future engines to become more efficient, with enhanced fuel economy and increased power output, accurate prediction of new designs is required over the full lifetime of an engine. The work carried out presents use of a local pressure coefficient of boundary shear strength of asperities value, taking into account the localised effects of surface texture, coating and surface deposition. XPS spectra analysis was also carried out to identify the surface depositions as a result of combustion, not previously taken into account during piston ring pack simulation. Friction was shown by simulation to drop by up to 30% between the compression and combustion stroke as a result of using a carriable coefficient of boundary shear strength of asperities. It was found that piston varnish on the liner corresponded to higher values of the pressure coefficient of boundary shear strength of asperities, therefore showing the importance of using real system components run under representative operating conditions or numerical analyses.
The authors of this work wish to show their thanks to the Engineering and Physical Sciences Research Council (EPSRC) and to our industrial collaborators AVL List GmbH for the financial and technical contributions they have made to this research.
- Mechanical, Electrical and Manufacturing Engineering