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Title: Development of a novel ultrasonic method for non-invasive measurement of oil films in piston ring contacts
Author: Avan, Emin Yusuf
ISNI:       0000 0004 2737 9161
Awarding Body: University of Sheffield
Current Institution: University of Sheffield
Date of Award: 2013
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Piston ring-liner contact in an internal combustion engine highly influences the amount of friction, oil consumption and wear that occurs. Proper lubrication of this contact is, therefore, necessary and is an important research area for the engine manufacturers to improve fuel efficiency and achieve the emission reduction targets proposed by authorities. However, the lubricant film formed in piston ring-liner contact is very thin and its measurement is challenging. Although the computer simulations, a low cost tool, are widely used to estimate the piston ring-liner interactions, they require a robust data for the validation of the mathematical models. In the past several techniques based on optical or electrical characteristics of the lubricant have been developed and applied to measure lubricant film thickness in piston rings, such as capacitance, resistance, eddy current and laser induced fluorescence methods. The main characteristic of these techniques is that they are invasive and require access to the piston ring-liner contact, and so penetrate the cylinder liner. Hence these measurement methods disturb the nature of the contact and influence ring lubrication. This thesis demonstrates the development of a novel ultrasonic method for non-invasive measurement of oil films within the piston ring contacts and the feasibility of the technique on a reciprocating test rig and a fired engine. After successful implementations of ultrasonic technique, the investigation results showed that the ultrasound technique can be used for the piston ring film thickness measurement. The ultrasonically measured film thickness values were consistent with those of other published data in the literature. The effects of load, speed and viscosity on the lubricant film formation were shown in the reciprocator tests. The investigation of the single cylinder engine test showed that the bespoke ultrasonic sensors could survive at high temperature that liner exterior surface experienced. The minimum lubricant films between the compression ring and liner were measured during the engine's power stroke and were typically less than 1 μm at TDC and ~4 μm at mid stroke. It has been shown that the ultrasonic technique demonstrates significant promise as a non-invasive and effective tool to assess the lubricant condition within the ring-liner contact. As being insensitive to test environment and more compact technique compared to the current measurement technologies, the ultrasonic method has a potential to be employed in a test vehicle.
Supervisor: Dwyer-Joyce, Rob Sponsor: Not available
Qualification Name: Thesis (Ph.D.) Qualification Level: Doctoral
EThOS ID:  DOI: Not available