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Kumar, Shubham (2019) An investigation into full-ring radial-gap air-riding seals for aeroengines. PhD thesis, University of Nottingham.

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Abstract

This thesis focuses on a study carried out for modelling, designing and testing a full-ring radial-gap air-riding seal configuration for applications in a Gas Turbine Engine.

On reviewing the open literature in the field of air riding seals, it was realised that the majority of existing seal designs were axial-gap type seals. One of the key challenges faced by axial-gap seals is that they have to contend with the differential thermal growth of the engine parts which results in net motions of the order of 1 cm. A radial-gap seal would benefit from the lower net travel that it would need to accommodate. The existing radial gap seals are circumferential seals with segmented seal ring. The segmented seal ring design faces issues like leakage in between segments, improper mating of segments, rubbing between parts etc., as the seal ring is segmented. A full-ring design would eliminate these issues, but one of the key challenge for this seal will be maintaining a positive clearance with the rotor for all operating conditions.

This thesis discusses the design of a radial-gap seal, with a full-ring configuration. The characteristics of the thin fluid film in the seal was determined by carrying out 1-D and 2-D simulations. This helped in determining the stiffness coefficients of the fluid film. It was observed that most of the lift generated in the fluid film was by hydrostatic means. Studies carried out were able to confirm that a converging seal gap is necessary for achieving positive film stiffness.

Steady state CFD analyses of the fluid film were offset shaft positions to generate the stiffness matrix of the film. This was followed by coupled Fluid-Structure Interaction analyses to determine the damping coefficients and the response of the fluid film to different shaft excitations.

The 3 analysis methods were found to have good correlation with each other in predicting the seal performance for different operating conditions. There were some discrepancies found in the experimental test data which meant that the experimental stiffness values did not correlate well with the simulation results, which, among other factors, might have been caused due to manufacturing error or faulty installation.

Item Type:	Thesis (University of Nottingham only) (PhD)
Supervisors:	Garvey, Seamus Morvan, Hervé
Keywords:	Seals (Closures); Aircraft gas-turbines
Subjects:	T Technology > TL Motor vehicles. Aeronautics. Astronautics
Faculties/Schools:	UK Campuses > Faculty of Engineering
Item ID:	59365
Depositing User:	Kumar, Shubham
Date Deposited:	18 Sep 2023 09:20
Last Modified:	18 Sep 2023 09:20
URI:	https://eprints.nottingham.ac.uk/id/eprint/59365

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