Fenton, Marcus Brian Mayhall (1994) Flow and heat transfer modelling of an automotive engine lubrication system. PhD thesis, University of Warwick.

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Abstract

This dissertation documents the thermodynamic and fluid mechanic analysis of an
engine lubrication system. A comprehensive thermofluid computer model was developed to
provide a flexible design analysis tool for the accurate prediction of oil pressures, flow rates
and temperatures at any point within any lubrication system. Technical and financial
support for the study was provided by Jaguar Cars.
A comprehensive literature review revealed that the past research in this field had
concentrated on either the thermofluid analysis of the lubrication system by engine testing,
or the detailed analysis of individual components. A small number of computer models were
developed for the flow analysis of the whole lubrication system. However, these models had
limited heat transfer prediction capabilities, some requiring measured engine temperature
data, and were not flexible enough to be employed as design tools.
The objective of this study was to develop a flexible steady-state thermofluid design
analysis tool, by integrating a flow analysis approach with a detailed analysis of the heat
transfer within the engine block. Mathematical models of the thermofluid behaviour of the
lubrication system components were developed and were implemented in a suite of
FORTRAN computer programs which formed the design analysis package.
A simple, linear flow model was initially developed to represent the system with a
combination of laminar pipes, pumps, filters, journal bearings, crank-shaft transfer holes
and cam bearing transfer holes. The linear program provided a rapid analysis tool, but the
accuracy of the results were limited by the simplified flow characteristics of the system
components. A more comprehensive and flexible non-linear flow model was developed, which
solved for the unknowns with an iterative technique. Additional component models with
non-linear flow characteristics, such as turbulent pipes, annular pipes, strainers, and oil
coolers, were developed. The non-linear solution technique was proven to be robust and
flexible and was subsequently used in all the analysis programs.
The heat transfer to the oil within the pressurised part of the lubrication system is
modelled by the heat transfer program. The engine block temperatures are calculated by the
engine block program. This program accounts for the heat transfer to the oil splashed on to
the internal surfaces of the engine. The engine geometry is represented by a series of block
elements and modelled as a nodal resistance network. This capability has particular
importance during the design stage, rapidly providing an estimate of the temperature profile
through the engine block, results which were previously only available from expensive and
slow FEA models.
It was shown that both the Jaguar AJ6 and V8 engine lubrication systems could be
analyzed in great detail. Engine tests showed that the predicted flow rates, pressures and
temperatures were in excellent agreement with measured values. The overall accuracy of
the results induced a high degree of confidence in the thermofluid model. The final analysis
package was proven to be easy to use, robust, rapid, flexible and accurate.
The design analysis package, developed during the course of this study, represents
a unique stand-alone simulation tool which can rapidly analyze any engine lubrication
system configuration. This package provides a valuable analysis tool which can be used to
optimise system designs at the initial design stage and the diagnosis of performance
problems during the development phase. Parametric studies can be easily carried out on the
lubrication system and engine block configuration to identify areas which can enhance heat
transfer to the oil. The steady-state analysis package forms an excellent platform for the
development of a full transient model. This would allow a detailed analysis of the lubrication
system during engine warm-up, with the aim of reducing engine emissions and determining
minimum oil requirements.

Item Type:	Thesis (PhD)
Subjects:	T Technology > TJ Mechanical engineering and machinery
Library of Congress Subject Headings (LCSH):	Internal combustion engines -- Lubrication -- Computer simulation, Internal combustion engines -- Lubrication -- Mathematical models, Heat -- Transmission, Automobiles -- Motors -- Thermodynamics, Lubrication and lubricants -- Fluid dynamics
Official Date:	June 1994
Dates:	Date Event June 1994 Submitted
Institution:	University of Warwick
Theses Department:	School of Engineering
Thesis Type:	PhD
Publication Status:	Unpublished
Supervisor(s)/Advisor:	Veshagh, Ali
Sponsors:	Jaguar Cars Ltd.
Extent:	2 v. (xi, 384 ; 277 leaves)
Language:	eng

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