PhD Studentship - Development of Advanced Simulation Tool and Experimental Campaign for Thrust Air Foil Bearing Systems

Research theme: Tribology

How to apply: uom.link/pgr-apply-2425

Number of positions: 1

This 3.5 year PhD project is fully funded for home and overseas applicants. Tuition fees will be paid and the successful candidate will receive an annual tax free stipend paid at the UKVI rate (£19,237 for 2024/25). We expect this to increase each year.

Air foil bearings (AFBs, also known as gas foil bearings or foil air bearings) are the key enablers of environmentally-friendly oil-free turbomachinery, including hydrogen fuel cell turbomachines. AFBs support the shaft by creating a cushion of air between the rotating part and a flexible foil structure, which includes a top foil and an underlying supporting foil. The air film pressure develops by hydrodynamic action as a result of the relative motion between the rotating part and the non-rotating top foil. Such bearings can either be journal bearings or thrust bearings, which are used to support loads that are radial (perpendicular to the shaft) and axial (along the shaft), respectively. In both cases, the foil structure comprises a top foil supported by an underlying foil structure which acts as a supporting spring. The majority of the existing AFB research has focused on journal bearings. However, thrust AFBs bring new challenges since they support axial loads which are typically irregular, and their load capacity is known to be particularly sensitive to thermal effects. The inclusion of thermal effects involves coupling the energy equation of the air film, with the heat transfer model to the various bearing parts, and the Reynolds Equation of the air film, which governs the air film pressure and thickness, thereby the load carrying capacity. The analysis will also yield a thermal map that is necessary to inform a cooling strategy to mitigate expansion and coatings degradation/wear. In the past years, a simulation tool to perform such analysis has been developed at the University of Manchester in collaboration with Cummins Engine Components (CEC). However, AFBs are complex with many variations in design, particularly the foil structural architectures. Hence there is the need to extend this simulation tool to be applicable across a wide range of potential design types. The PhD will be conducted in collaboration with CEC [Turbochargers Division] who are developing fuel cell turbomachines for commercial applications.

The aims of this PhD project are:

1. To extend the capability of the existing simulation tool to be applicable across a wide range of potential design types.
2. To develop experimental capability for validation tests.
3. To correlate and validate simulations with experimental data and refine models accordingly.

The realisation of the first aim involves an assessment of using a commercial multi-physics software package for some or all domains of the thermo-elastic-hydrodynamic (TEHD) model of the air foil thrust system with user-supplied foil structure architectures. The realisation of the second and third aims involves the commissioning and development of an existing test rig, as well as the provision of additional experimental data from Cummins Engine Components.

Applicants should have, or expect to achieve, at least a 2.1 honours degree or a master’s (or international equivalent) in a relevant science or engineering related discipline.

To apply, please Dr Bonello - philip.bonello@manchester.ac.uk. Please include details of your current level of study, academic background and any relevant experience and include a paragraph about your motivation to study this PhD project.

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