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Please use this identifier to cite or link to this item: https://dspace.lboro.ac.uk/2134/18460

Title: Multi-phase thermal cavitation flow in rough conforming and partially conforming conjunctions
Authors: Shahmohamadi, Hamed
Keywords: Finite volume CFD
Multi-phase flow
Cavitation
Tribological conjunctions
Friction
Issue Date: 2015
Publisher: © Hamed Shahmohamadi
Abstract: The main aim of this research was to investigate the mechanism of cavitation in conforming and partially conforming tribological conjunctions. The effect of cavitation on load carrying capacity and frictional performance of is also investigated. This is important with regards to fuel efficiency in internal combustion (IC) engines. Friction accounts for 15–20% of IC engine losses. The piston–cylinder system contributes to 40–50% of these, with the compression ring(s) being responsible for most of this. This is because the primary function of the ring is to seal the combustion chamber, thus small emerging gaps lead to increased friction. In fact, compression ring(s) expend 3–5% of engine input fuel energy. The share of frictional losses of engine bearings is approximately 20–25%. Traditionally, prediction of performance of tribological conjunctions has been studied using Reynolds equation. When the effect of cavitation is considered, various cavitation algorithms with associated boundary conditions for lubricant rupture and reformation are proposed. These include Elrod, and Elrod and Coyne algorithms, as well as boundary conditions such as Swift-Stieber, JFO and Prandtl-Hopkins. There are a number of assumptions embodied in these approaches, as well as the use of Reynolds equation itself. These approaches do not uphold the continuity of mass and momentum in multi-phase flow, in cavitation beyond the lubricant film rupture. A detailed methodology for multi-phase flow, comprising simultaneous solution of Navier-Stokes, energy and lubricant rheological state equations is developed. [Continues.]
Description: A Doctoral Thesis. Submitted in partial fulfilment of the requirements for the award of Doctor of Philosophy of Loughborough University.
Sponsor: Lloyd's Register Foundation.
URI: https://dspace.lboro.ac.uk/2134/18460
Appears in Collections:PhD Theses (Mechanical, Electrical and Manufacturing Engineering)

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