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Title: The measurement of film deposit on diesel engine pistons
Author: Zareh, A.
Awarding Body: University College of Swansea
Current Institution: Swansea University
Date of Award: 1991
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The method used for evaluating and rating lubricant effects on deposit accumulation on diesel engine pistons involves visual (subjective) assessment of the severity of the deposit after a full test is completed, using a Caterpillar diesel engine. Because this is costly in terms of time and effort involved, it has become necessary to establish an alternative means of evaluation. It was recognised early in the current investigation that one solution would be to monitor the onset and development of the deposit during the engine test. An alternative approach, however, was to establish a cheap and quick method for screening lubricants by using a simulated piston-cylinder test system. The thesis describes the project strategy and approach adopted in investigating the problem, and discusses the results obtained from using a bench-tip simulated deposit test rig in conjunction with a finite element-based theoretical model of the piston's thermal behaviour. The major contributing factors to the deposit formation phenomenon have been identified, and the details of its properties, characteristics and piston-cylinder environment are presented. A number of potential techniques for measuring/monitoring deposit formation were assessed, leading to the experimental evaluation of piston temperature mesurement using thermocouples, thermal mapping of the exterior suface using infra-red techniques, together with the initial assessment of ultrasound and capacitance measurements. A theoretical study of the piston thermal behaviour was undertaken using the finite element method which demonstrated the effects of deposit and piston rings on piston thermal behaviour. The results obtained, when coupled with the experimental measurement of piston thermal behaviour, identified the temperature measurement as a viable method to detect the onset and build-up of deposit. It is recommended that a test procedure, based on the present test system, be fully established for screening various piston-lubricant combinations. It is also recommended to further develop the capability of the present theoretical model. At the same time, it would be appropriate to re-examine alternative experimental methods for determining the onset and build-up of deposit and to establish a motored test arrangement using a diesel engine unit as a precursor to carrying out monitoring trials on a fully fired engine.
Supervisor: Not available Sponsor: Not available
Qualification Name: Thesis (Ph.D.) Qualification Level: Doctoral
EThOS ID:  DOI: Not available