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The influence of fan root flow on the aerodynamic of a low-pressure compressor transition duct

journal contribution
posted on 28.10.2019 by Duncan Walker, Ian Mariah, Dimitra Tsakmakidou, Hiren Vadhvana, Chris Hall
To reduce fuel-burn and emissions there is a drive towards higher bypass ratio and smaller high-pressure ratio core engines. This makes the design of the ducts connecting compressor spools more challenging as the higher radius change increases aerodynamic loading. This is exacerbated at inlet to the engine core by fan root flow which is characterised by a hub-low pressure profile and large secondary flow structures. Additionally, shorter, lighter nacelles mean that the intake may not provide a uniform inlet flow when the aircraft is at an angle of attack or subject to cross winds. Such inlet distortion can further degrade the flow entering the engine. A combination of experiments and CFD have been used to examine the aerodynamics of an engine section splitter (ESS) and transition duct designed to feed the low-pressure spool of a high bypass ratio turbofan. A test facility incorporating a 1½ stage axial compressor was used to compare system performance for a flat rotor exit profile to one with a hub deficient flow. Validated RANS CFD was then used to further investigate the effects of increased inlet boundary layer thickness and bulk swirl distortion at rotor inlet. These changes were seen to have a surprisingly small effect on the flow at duct exit. However, increased secondary flows were observed which degraded the performance of the ESS and significantly increased loss. Nevertheless, the enhanced mixing delayed separation in the duct suggesting that overall the design was reasonably robust albeit with increased system loss.

Funding

Aerospace Technology Institute as part of the iCORE (Integrated Core Technologies) program.

History

School

  • Aeronautical, Automotive, Chemical and Materials Engineering

Department

  • Aeronautical and Automotive Engineering

Published in

Journal of Turbomachinery

Volume

142

Issue

1

Publisher

American Society of Mechanical Engineers

Version

AM (Accepted Manuscript)

Rights holder

© ASME

Publisher statement

This is an Open Access Article. It is published by ASME under the Creative Commons Attribution 4.0 Unported Licence (CC BY). Full details of this licence are available at: http://creativecommons.org/licenses/by/4.0/

Acceptance date

18/10/2019

Publication date

2019-10-22

Copyright date

2020

ISSN

0889-504X

eISSN

1528-8900

Other identifier

Paper No: TURBO-19-1210

Language

en

Depositor

Dr Duncan Walker Deposit date: 25 October 2019

Article number

011002

Licence

Exports