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Aerodynamic influence of a bleed on the last stage of a low-pressure compressor and S-duct

journal contribution
posted on 12.08.2021, 12:29 by Apostolos SpanelisApostolos Spanelis, Duncan WalkerDuncan Walker
Abstract This paper uses Computational Fluid Dynamics to investigate the effect of an engine handling bleed situated on the outer casing downstream of the last rotor stage of a low-pressure compressor and upstream of the outlet guide vane and S-shaped duct. The model, validated against existing experimental data, utilized an unsteady RANS solver incorporating a Reynolds stress closure to examine the unsteady component interactions. The results showed that at bleed rates less than 25% of the mainstream flow the bleed effects were negligible. However, at higher bleed rates performance was significantly degraded. A uniform flow extraction hypothesis was employed to separate the positional bias effects from the bulk flow diffusion. This revealed that the bleed-induced radial flow distortion can significantly affect the OGV loading distribution, which thereby dictates the position and type of stall within the OGV passage. Extraction of the rotor tip leakage via the shroud bleed, combined with the radial flow distortion, contributed to a 28% reduction in duct loss at 10% bleed and up to 50% reduced loss at 25% bleed. The actual amount of flow required to be extracted for an OGV stall to develop, was 30%. That was independent of the bleed location and the type of stall. For bleeds up to 20%, the S-duct displayed a remarkable resilience and consistency of flow variables at duct exit. However, a stalled OGV deteriorated the radial flow uniformity that was presented to the high-pressure compressor.

History

School

  • Aeronautical, Automotive, Chemical and Materials Engineering

Department

  • Aeronautical and Automotive Engineering

Published in

Journal of Turbomachinery

Volume

144

Issue

2

Publisher

ASME International

Version

AM (Accepted Manuscript)

Rights holder

© ASME

Publisher statement

This paper was accepted for publication in the journal Journal of Turbomachinery and the definitive published version is available at https://doi.org/10.1115/1.4052134

Acceptance date

27/07/2021

Publication date

2021-09-27

Copyright date

2021

ISSN

0889-504X

eISSN

1528-8900

Language

en

Depositor

Dr Duncan Walker. Deposit date: 12 August 2021

Article number

021007