Details
| Original language | English |
|---|---|
| Title of host publication | Structures and Dynamics |
| Subtitle of host publication | Aerodynamics Excitation and Damping; Bearing and Seal Dynamics; Emerging Methods in Engineering Design, Analysis, and Additive Manufacturing |
| Publisher | American Society of Mechanical Engineers(ASME) |
| ISBN (electronic) | 9780791888025 |
| Publication status | Published - 28 Aug 2024 |
| Event | 69th ASME Turbo Expo 2024: Turbomachinery Technical Conference and Exposition, GT 2024 - London, United Kingdom (UK) Duration: 24 Jun 2024 → 28 Jun 2024 |
Publication series
| Name | Proceedings of the ASME Turbo Expo |
|---|---|
| Volume | 10A |
Abstract
In literature, two common parameters to indicate flutter sensitivity are the reduced frequency and the amount of twist present in the combined first flap mode. A critical parameter is the plunge-to-twist incidence ratio, which is a function of both frequency and twist-to-plunge ratio in the mode shape. However, the limit of this stability criterion for real fan blades is not fully understood yet. This paper investigates the influence of plunge-to-pitch incidence ratio on a 3D transonic test case, the scaled composite UHBR fan of the CA3ViAR project, with the aim to understand the validity of the plunge-to-twist incidence ratio as a flutter parameter for transonic and three-dimensional fan blades. This fan was designed with the unconventional goal to achieve stable operation at the design point but flutter at throttled off-design conditions. The design was done by varying the CFRP ply material and orientation towards specific reduced frequencies and twist-to-plunge ratios to drive the aerodynamic stability towards the desired behaviour. Here, the aerodynamic damping of a set of 3D mode-shapes based on variations in the composite ply-layup are simulated using TRACE Harmonic Balance for different reduced frequencies. Flutter stability for different reduced frequencies and twist-to-plunge ratio is mapped for several operating points. The results show that the stability boundary only follows lines of constant plunge-to-pitch incidence ratio in some regions of the map but deviates in others. The key deviations are then explained by analysing the aeroacoustic conditions. The study demonstrates that the validity of the plunge-to-twist incidence ratio parameter depends on the flutter mechanism. It is not valid inside the region where the acoustic wave is cut-on upstream but cut-off downstream. To the authors’ knowledge, this is the first time that limits of this stability criterion for fan flutter were explicitly shown and explained.
Keywords
- Aeroelasticity, flutter, mode shape, plunge-to-twist incidence ratio, UHBR Fan
ASJC Scopus subject areas
- Engineering(all)
- General Engineering
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Structures and Dynamics : Aerodynamics Excitation and Damping; Bearing and Seal Dynamics; Emerging Methods in Engineering Design, Analysis, and Additive Manufacturing. American Society of Mechanical Engineers(ASME), 2024. V10AT21A009 (Proceedings of the ASME Turbo Expo; Vol. 10A).
Research output: Chapter in book/report/conference proceeding › Conference contribution › Research › peer review
}
TY - GEN
T1 - The influence of mode shape on flutter stability of a scaled composite UBHR fan
AU - Goessling, Jan
AU - Maroldt, Niklas
AU - Stapelfeldt, Sina
N1 - Publisher Copyright: Copyright © 2024 by ASME.
PY - 2024/8/28
Y1 - 2024/8/28
N2 - In literature, two common parameters to indicate flutter sensitivity are the reduced frequency and the amount of twist present in the combined first flap mode. A critical parameter is the plunge-to-twist incidence ratio, which is a function of both frequency and twist-to-plunge ratio in the mode shape. However, the limit of this stability criterion for real fan blades is not fully understood yet. This paper investigates the influence of plunge-to-pitch incidence ratio on a 3D transonic test case, the scaled composite UHBR fan of the CA3ViAR project, with the aim to understand the validity of the plunge-to-twist incidence ratio as a flutter parameter for transonic and three-dimensional fan blades. This fan was designed with the unconventional goal to achieve stable operation at the design point but flutter at throttled off-design conditions. The design was done by varying the CFRP ply material and orientation towards specific reduced frequencies and twist-to-plunge ratios to drive the aerodynamic stability towards the desired behaviour. Here, the aerodynamic damping of a set of 3D mode-shapes based on variations in the composite ply-layup are simulated using TRACE Harmonic Balance for different reduced frequencies. Flutter stability for different reduced frequencies and twist-to-plunge ratio is mapped for several operating points. The results show that the stability boundary only follows lines of constant plunge-to-pitch incidence ratio in some regions of the map but deviates in others. The key deviations are then explained by analysing the aeroacoustic conditions. The study demonstrates that the validity of the plunge-to-twist incidence ratio parameter depends on the flutter mechanism. It is not valid inside the region where the acoustic wave is cut-on upstream but cut-off downstream. To the authors’ knowledge, this is the first time that limits of this stability criterion for fan flutter were explicitly shown and explained.
AB - In literature, two common parameters to indicate flutter sensitivity are the reduced frequency and the amount of twist present in the combined first flap mode. A critical parameter is the plunge-to-twist incidence ratio, which is a function of both frequency and twist-to-plunge ratio in the mode shape. However, the limit of this stability criterion for real fan blades is not fully understood yet. This paper investigates the influence of plunge-to-pitch incidence ratio on a 3D transonic test case, the scaled composite UHBR fan of the CA3ViAR project, with the aim to understand the validity of the plunge-to-twist incidence ratio as a flutter parameter for transonic and three-dimensional fan blades. This fan was designed with the unconventional goal to achieve stable operation at the design point but flutter at throttled off-design conditions. The design was done by varying the CFRP ply material and orientation towards specific reduced frequencies and twist-to-plunge ratios to drive the aerodynamic stability towards the desired behaviour. Here, the aerodynamic damping of a set of 3D mode-shapes based on variations in the composite ply-layup are simulated using TRACE Harmonic Balance for different reduced frequencies. Flutter stability for different reduced frequencies and twist-to-plunge ratio is mapped for several operating points. The results show that the stability boundary only follows lines of constant plunge-to-pitch incidence ratio in some regions of the map but deviates in others. The key deviations are then explained by analysing the aeroacoustic conditions. The study demonstrates that the validity of the plunge-to-twist incidence ratio parameter depends on the flutter mechanism. It is not valid inside the region where the acoustic wave is cut-on upstream but cut-off downstream. To the authors’ knowledge, this is the first time that limits of this stability criterion for fan flutter were explicitly shown and explained.
KW - Aeroelasticity
KW - flutter
KW - mode shape
KW - plunge-to-twist incidence ratio
KW - UHBR Fan
UR - http://www.scopus.com/inward/record.url?scp=85204394235&partnerID=8YFLogxK
U2 - 10.1115/GT2024-126529
DO - 10.1115/GT2024-126529
M3 - Conference contribution
AN - SCOPUS:85204394235
T3 - Proceedings of the ASME Turbo Expo
BT - Structures and Dynamics
PB - American Society of Mechanical Engineers(ASME)
T2 - 69th ASME Turbo Expo 2024: Turbomachinery Technical Conference and Exposition, GT 2024
Y2 - 24 June 2024 through 28 June 2024
ER -