Abstract
Lubricants are used to simultaneously reduce the friction and wear of engineering components. In many applications, lubricants degrade and are contaminated over time, and as a result, the viscosity of the lubricant is affected. This may impact the tribological performance of the lubricant by altering the lubricant film thickness in the contact. Friction, from shearing of the lubricant in the contact, may also change.
In the case of engine lubrication, lubricants can be contaminated by the fuel, which in some cases may contain components which are also surface active. As such, as well as changing the viscosity of the lubricant, fuel contaminants might also change the interaction between the lubricant and the surface, thus altering the flow of the lubricant in the contact.
To investigate how the rheology of lubricants that are affected by fuel contamination, measurements will be taken using fluorescence anisotropy, to determine the local viscosity distribution in an electrohydrodynamic (EHD) contact. Flow of the contaminated lubricant will also be monitored. This will determine if changes in friction are due to a reduction in local viscosity, a surface effect, or both. The effects of both a model reference fuel and model commercial fuel will be explored in this study.