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Impact of flow unsteadiness on steady-state gas-path stagnation temperature measurements

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journal contribution
posted on 15.05.2018, 10:27 by Clare Bonham, Mark Brend, Adrian Spencer, Katsuyoshi Tanimizu, Dylan Wise
Steady-state stagnation temperature probes are used during gas turbine engine testing as a means of characterising turbomachinery component performance. The probes are located in the high-velocity gas-path, where temperature recovery and heat transfer effects cause a shortfall between the measured temperature and the flow stagnation temperature. To improve accuracy, the measurement shortfall is corrected post-test using data acquired at representative Mach numbers in a steady aerodynamic calibration facility. However, probes installed in engines are typically subject to unsteady flows, which are characterised by periodic variations in Mach number and temperature caused by the wakes shed from upstream blades. The present work examines the impact of this periodic unsteadiness on stagnation temperature measurements by translating probes between jets with dissimilar Mach numbers. For conventional Kiel probes in unsteady flows, a greater temperature measurement shortfall is recorded compared to equivalent steady flows, which is related to greater conductive heat loss from the temperature sensor. This result is important for the application of post-test corrections, since an incorrect value will be applied using steady calibration data. A new probe design with low susceptibility to conductive heat losses is therefore developed, which is shown to deliver the same performance in both steady and unsteady flows. Measurements from this device can successfully be corrected using steady aerodynamic calibration data, resulting in improved stagnation temperature accuracy compared to conventional probe designs. This is essential for resolving in-engine component performance to better than +/-0.5% across all component pressure ratios.

Funding

This research was funded by the European Commission under the Framework 7 STARGATE project.

History

School

  • Aeronautical, Automotive, Chemical and Materials Engineering

Department

  • Aeronautical and Automotive Engineering

Published in

Journal of Engineering for Gas Turbines and Power-Transactions of the ASME

Volume

140

Issue

12

Citation

BONHAM, C. ... et al, 2018. Impact of flow unsteadiness on steady-state gas-path stagnation temperature measurements. Journal of Engineering for Gas Turbines and Power, 140 (12), paper no. 122602.

Publisher

© ASME (American Society of Mechanical Engineers)

Version

AM (Accepted Manuscript)

Publisher statement

This article 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

11/04/2018

Publication date

2018-08-06

ISSN

0742-4795

Language

en

Article number

122602