The University of Southampton
University of Southampton Institutional Repository

Characterisation of rain erosion at ex-service turbofan blade leading edges

Characterisation of rain erosion at ex-service turbofan blade leading edges
Characterisation of rain erosion at ex-service turbofan blade leading edges

Rain erosion of turbofan blades creates problems in the aeronautics community, since the changes of profiles on leading edges affect aerodynamic performance that subsequently leads to significant efficiency drop for the aircraft engine. Water-hammer pressure induced by droplet impingements is primarily responsible for the damaged induced during the initial compression stage. As the surface roughened, the damage mechanism is then governed by lateral flow jetting assisted with hydraulic penetration. Studies on WDE are restricted to laboratory testing with simplified conditions and samples. Hence, this will be the first study to demonstrate real-life WDE damage on real turbofan blades during their ‘complicated’ in-service conditions. A set of Ti-6Al-4V ex-service turbofan blades are sectioned to examine their in-service degradation. Different parts of the blade, with impact velocities ranging from 144 m s−1 to 396 m s−1, were selected to study the effect of impact velocity on rain erosion damage. Erosion morphology and the damage mechanisms are characterised with Alicona profilometer and SEM. The results reveal that rain erosion occurs exclusively at the leading edges. Increase of rain erosion severity with increasing impact velocity is identified. The normalised volume loss is proportional to Vn, where V is the impact velocity, ranging from 286 m s−1 to 348 m s−1, and the exponent (n) is estimated to be around 8 for Ti-6Al-4V ex-service turbofan blade, which agrees with the literature from laboratory tests. The damage features during early incubation period cannot be detected due to the roughening of the leading edges. However, intergranular fracture is detected at the tip of the leading edge with less severe damage. In the steady state, material removal appears to be due to coalescence of microcracks to form erosion craters. The cracks continue to propagate from the side wall and bottom of the erosion craters, attributable to the joint effect of lateral outflow jetting and hydraulic penetration induced by repetitive droplet impingements. Thus, the present research is an invaluable opportunity to validate the results obtained from laboratory tests by comparing with the real-life WDE, which then helps to further elucidate the damage mechanisms behind WDE.

Ex-service turbofan blade, Ti-6Al-4V, Water droplet erosion
0043-1648
539-551
Ma, Dina
ae2dcfae-cf5b-4492-b6dc-2e6b86960431
Harvey, Terry J.
3b94322b-18da-4de8-b1af-56d202677e04
Wellman, Richard
933354f5-e4ff-448e-b6b5-4caef14187a4
Wood, Robert J.
d9523d31-41a8-459a-8831-70e29ffe8a73
Ma, Dina
ae2dcfae-cf5b-4492-b6dc-2e6b86960431
Harvey, Terry J.
3b94322b-18da-4de8-b1af-56d202677e04
Wellman, Richard
933354f5-e4ff-448e-b6b5-4caef14187a4
Wood, Robert J.
d9523d31-41a8-459a-8831-70e29ffe8a73

Ma, Dina, Harvey, Terry J., Wellman, Richard and Wood, Robert J. (2019) Characterisation of rain erosion at ex-service turbofan blade leading edges. Wear, 426–427 (Part A), 539-551. (doi:10.1016/j.wear.2018.12.050).

Record type: Article

Abstract

Rain erosion of turbofan blades creates problems in the aeronautics community, since the changes of profiles on leading edges affect aerodynamic performance that subsequently leads to significant efficiency drop for the aircraft engine. Water-hammer pressure induced by droplet impingements is primarily responsible for the damaged induced during the initial compression stage. As the surface roughened, the damage mechanism is then governed by lateral flow jetting assisted with hydraulic penetration. Studies on WDE are restricted to laboratory testing with simplified conditions and samples. Hence, this will be the first study to demonstrate real-life WDE damage on real turbofan blades during their ‘complicated’ in-service conditions. A set of Ti-6Al-4V ex-service turbofan blades are sectioned to examine their in-service degradation. Different parts of the blade, with impact velocities ranging from 144 m s−1 to 396 m s−1, were selected to study the effect of impact velocity on rain erosion damage. Erosion morphology and the damage mechanisms are characterised with Alicona profilometer and SEM. The results reveal that rain erosion occurs exclusively at the leading edges. Increase of rain erosion severity with increasing impact velocity is identified. The normalised volume loss is proportional to Vn, where V is the impact velocity, ranging from 286 m s−1 to 348 m s−1, and the exponent (n) is estimated to be around 8 for Ti-6Al-4V ex-service turbofan blade, which agrees with the literature from laboratory tests. The damage features during early incubation period cannot be detected due to the roughening of the leading edges. However, intergranular fracture is detected at the tip of the leading edge with less severe damage. In the steady state, material removal appears to be due to coalescence of microcracks to form erosion craters. The cracks continue to propagate from the side wall and bottom of the erosion craters, attributable to the joint effect of lateral outflow jetting and hydraulic penetration induced by repetitive droplet impingements. Thus, the present research is an invaluable opportunity to validate the results obtained from laboratory tests by comparing with the real-life WDE, which then helps to further elucidate the damage mechanisms behind WDE.

Text
WOM 2019 paper_revised - Accepted Manuscript
Download (16MB)
Text
WOM 2019 paper published - Version of Record
Restricted to Repository staff only
Request a copy

More information

Accepted/In Press date: 19 December 2018
e-pub ahead of print date: 10 April 2019
Published date: 30 April 2019
Venue - Dates: Wear of Materials 2019: 22nd International Conference on Wear of Materials, Hyatt Regency Miami, Miami, United States, 2019-04-14 - 2019-04-18
Keywords: Ex-service turbofan blade, Ti-6Al-4V, Water droplet erosion

Identifiers

Local EPrints ID: 432596
URI: http://eprints.soton.ac.uk/id/eprint/432596
ISSN: 0043-1648
PURE UUID: 3feb74db-3737-47fc-8529-18766d26aa85
ORCID for Robert J. Wood: ORCID iD orcid.org/0000-0003-0681-9239

Catalogue record

Date deposited: 19 Jul 2019 16:42
Last modified: 18 Feb 2021 16:43

Export record

Altmetrics

Contributors

Author: Dina Ma
Author: Terry J. Harvey
Author: Richard Wellman
Author: Robert J. Wood ORCID iD

University divisions

Download statistics

Downloads from ePrints over the past year. Other digital versions may also be available to download e.g. from the publisher's website.

View more statistics

Atom RSS 1.0 RSS 2.0

Contact ePrints Soton: eprints@soton.ac.uk

ePrints Soton supports OAI 2.0 with a base URL of http://eprints.soton.ac.uk/cgi/oai2

This repository has been built using EPrints software, developed at the University of Southampton, but available to everyone to use.

We use cookies to ensure that we give you the best experience on our website. If you continue without changing your settings, we will assume that you are happy to receive cookies on the University of Southampton website.

×