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An experimental, aerodynamic evaluation of design choices for a low-pressure compressor transition duct

journal contribution
posted on 19.04.2021, 10:25 by Duncan Walker, Ian Mariah, Chris Hall
The S-shaped duct which transfers flow from the low-pressure fan to the engine core in large civil turbofans presents a challenging problem. Aerodynamically it has a spatially and temporarily varying inlet flow combined with a complex flow field which develops under the combined influence of pressure gradients and streamline curvature. It must also accommodate the transfer of structural loads and services across the main gas path. This necessitates the use of structural vanes which can compromise aerodynamics, introduce unwanted component interactions, and erode performance. This must all be achieved with minimum length/weight and without flow separation. This paper presents a comprehensive aerodynamic evaluation of three design options for a transition duct containing (i) a long-chord, structural compressor outlet guide vane, (ii) a aerodynamically optimal but non-structural outlet guide vane in conjunction with a small number of load bearing struts and (iii) a fully integrated outlet guide vane and strut design. Evaluation was performed using a low-speed test facility incorporating a 1 ½ stage axial compressor and engine representative transition duct. Measured data suggest that all the options were viable. However, the aerodynamic vane and discrete struts produced the lowest system loss with the other two options being comparable. The performance of the structural vane was sensitive to off-design conditions producing a notable increase in loss at a low flow coefficient. The optimized aerodynamic vanes were much less sensitive to off-design conditions whilst the fully integrated design showed only very small changes in 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

143

Issue

9

Publisher

American Society of Mechanical Engineers

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/10.1115/1.4050598.

Acceptance date

09/02/2021

Publication date

2021-05-03

Copyright date

2021

ISSN

0889-504X

eISSN

1528-8900

Language

en

Depositor

Dr Duncan Walker. Deposit date: 9 February 2021

Article number

091004