Abstract

During transient gas turbine operating cycles, the radial clearance between the rotating blades and the stationary casing is governed by the thermal stresses and radial growth of the compressor discs. Robust and accurate prediction of the temperature and heat transfer inside compressor cavities is critical to controlling these clearances and the design of reliable and efficient engines. This paper presents a fully predictive model to determine disc temperatures and shroud heat fluxes for a closed disc cavity (rotating cylindrical annulus), simulating an engine compressor. This is the first published reduced-order modelling of compressor cavities during engine transients in literature and the most detailed publication of transient experimental data in this context. Due to the conjugate nature of the heat transfer, a conduction model of the compressor disc and a model of the flow and heat transfer in the cavity between the co-rotating discs are included. The conduction was computed using a two-dimensional finite element solver, and the disc heat transfer was calculated assuming conductive laminar Ekman layers on the disc surfaces. Correlations for free convection on flat plates are used to model the heat transfer on the inner and outer radii of the rotating cavity. The transient core temperatures were calculated in a quasi-steady manner, with the heat transfer at every time step predicted assuming zero net heat flow. The model was validated using new transient data collected from the Compressor Cavity Rig at the University of Bath. The model shows consistent agreement with all experimental cases, providing insight into the conjugate relationship between the disc and shroud heat transfer, revealing that disc heat transfer is sustained long after there is no convective heat transfer from the shroud. This approach has direct application to practical thermo-mechanical codes, contributing to the design of next-generation, net-zero aerospace architectures.

Original languageEnglish
Article number120759
Number of pages14
JournalApplied Thermal Engineering
Volume230
Issue numberPart B
Early online date15 May 2023
DOIs
Publication statusPublished - 25 Jul 2023

Bibliographical note

Funding Information:
This work was supported by the UK Engineering and Physical Sciences Research Council , under the grant number EP/P003702/1 in collaboration with Rolls-Royce plc. Support from colleagues are gratefully acknowledged. In particular, we thank Peter Smout, Jake Williams and Jeff Medema.

Data availability:
The data that supports the findings of this study are available within the article

Keywords

  • Buoyancy-induced flow
  • Closed cavity
  • High-pressure compressor
  • Mathematical modelling
  • Transient cycles

ASJC Scopus subject areas

  • Energy Engineering and Power Technology
  • Mechanical Engineering
  • Fluid Flow and Transfer Processes
  • Industrial and Manufacturing Engineering

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