Imperial College London
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Professor Mehdi Vahdati

Faculty of Engineering, Department of Mechanical Engineering

Principal Research Fellow
 
 
 
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Contact

 

+44 (0)20 7594 7073m.vahdati

 
 
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Location

 

606City and Guilds BuildingSouth Kensington Campus

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Summary

 

Publications

Citation

BibTex format

@inproceedings{Stapelfeldt:2017:10.1115/GT2017-64167,
author = {Stapelfeldt, S and Vahdati, M},
doi = {10.1115/GT2017-64167},
title = {On the importance of engine-representative models for fan flutter predictions},
url = {http://dx.doi.org/10.1115/GT2017-64167},
year = {2017}
}
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RIS format (EndNote, RefMan)

TY  - CPAPER
AB  - This paper examines the factors which can result in discrepancies between rig tests and numerical predictions of the flutter boundary for fan blades. Differences are usually attributed to the deficiency of CFD models for resolving the flow at off-design conditions. This work was initiated as a result of inconsistencies between the flutter prediction of two rig fan blades, called here Fan F1 and Fan F2. The numerical results agreed well with the test data in terms of flutter speed and nodal diameter for both fans. However, they predicted a significantly higher flutter margin for F2 than for Fan F1, while rig tests showed that the two blades had similar flutter margins. A new set of flutter computations for both blades using the whole LP domain (intake, fan, OGV and ESS) was therefore performed. The new set of computations considered the effects of the acoustic liner and mistuning for both blades. The results of this work indicate that the previous discrepancies between CFD and tests were due to: 1. Differences in the effectiveness of the acoustic liner in attenuating the pressure wave created by the blade vibration as a result of differences in flutter frequencies between the two fan blades. 2. Differences in the level of unintentional mistuning of the two fan blades due to manufacturing tolerances. In the second part of this research, the effects of blade misstaggering and inlet temperature on aerodynamic damping were investigated. The data presented in this paper clearly show that manufacturing and environmental uncertainties can play an important role in the flutter stability of a fan blade. They demonstrate that aeroelastic similarity is not necessarily achieved if only aerodynamic properties and the traditional aeroelastic parameters, reduced frequency and mass ratio, are maintained. This emphasises the importance of engine-representative models, in addition to an accurate and validated CFD code, for the reliable prediction of the flutter boundary.
AU  - Stapelfeldt,S
AU  - Vahdati,M
DO  - 10.1115/GT2017-64167
PY  - 2017///
TI  - On the importance of engine-representative models for fan flutter predictions
UR  - http://dx.doi.org/10.1115/GT2017-64167
ER  -
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