In the last decades the aero-engine design has been more and more focusing on reducing weight and polluting emissions, yielding a fewer number of highly loaded and thinner blades. This leads to undesired vibration phenomena, such as flutter and forced response. Flutter is a major concern to be taken into account, since it is a self-excited and self-sustained aeroelastic instability phenomenon. The development of accurate numerical prediction methods is thus necessary in order to determine, during the design loop, whether a blade-row will or will not experience flutter. This paper presents a numerical assessment of flutter stability on a low pressure turbine rotor row in two different configurations designed and tested in the context of the European project FUTURE. The analyses have been carried out on both the cantilever and interlocked configurations of a single-pitch row sector for the first bending mode family. The modal analysis has been performed with an Open Source FEM tool (CalculiX) able to deal with complex interlocked rotor geometries and to model contact interfaces by using dedicated contact models with friction. On the other hand, the unsteady CFD simulations with moving blades have been carried out with the TRAF code, an in-house solver developed at the University of Florence which implements a non-linear method for flutter evaluation. The comparison between the cantilever and interlocked configurations in terms of flutter behavior is provided, showing the stabilization effect of the blade tip interlock device. The results proved to be in good agreement with the evidence coming from the experimental campaign.

1.
Arnone
,
A.
(
1994
).
Viscous analysis of three-dimensional rotor flow using a multigrid method
.
Journal of Turbomachinery
,
116
:
435
445
.
2.
Barreca
,
P.
,
Pinelli
,
L.
,
Vanti
,
F.
, and
Arnone
,
A.
(
2018
).
Aeroelastic investigation of a transonic compressor rotor with multi-row effects
.
Energy Procedia
(
2018
).
148
:
58
65
3.
Biagiotti
,
S.
Pinelli
,
L.
,
Poli
,
F.
,
Vanti
,
F.
, and
Arnone
,
A.
(
2018
).
Numerical study of flutter stabilization in low pressure turbine rotor with intentional mistuning
.
Energy Procedia
(
2018
).
148
:
98
105
4.
Dhondt
,
G.
(
2018
)
CalculiX CrunchiX USER’S MANUAL version 2.14
5.
Pinelli
,
L.
and
Vanti
,
F.
and
Arnone
,
A.
and
Beßling
,
B.
and
Vogt
,
D.
(
2017
). Influence of tip shroud modeling on the flutter stability of a low pressure turbine rotor. In
ASME Turbo Expo 2019
.
ASME paper GT2019-91204.
6.
Panovsky
,
J.
and
Kielb
,
R.E.
(
2000
).
A design method to prevent low pressure turbine blade flutter
Journal of Turbomachinery
,
122
:
89
98
.
7.
Rice
,
T.
and
Bell
,
D.
and
Singh
,
D.
(
2009
).
Identification of the stability margin between safe operation and the onset of blade flutter
Journal of Turbomachinery
,
131
(
1
):
011009
.
8.
Tchernycheva
,
O.V.
and
Regard
,
S.
and
Moyroud
,
F.
and
Fransson
,
T.H.
(
2000
) Sensitivity analysis of blade mode shape on flutter of two-dimensional turbine blade sections In
ASME Turbo Expo 2000
.
ASME paper 2000-GT-0379.
9.
Pinelli
,
L.
,
Poli
,
F.
,
Arnone
,
A.
, and
Schipani
,
C.
(
2009
).
A time-accurate 3D method for turbomachinery blade flutter analysis
. In
12ᵗʰ In-ternational Symposium on Unsteady Aerodynamics, Aeroacoustics and Aeroelasticity of Turbomachines (ISUAAAT)
. September 1–4,
London, UK
, paper I12-S8-3.
10.
Pinelli
,
L.
and
Poli
,
F.
and
Bellucci
,
J.
and
Giovannini
,
M.
and
Arnone
,
A.
Evaluation of Fast Numerical Methods for Turbomachinery Blade Flutter Analysis
In
14ᵗʰ International Symposium on Unsteady Aerodynamics, Aeroacoustics and Aeroelasticity of Turbomachines (ISUAAAT)
. September 8–11,
Stockholm, SE
, paper I14-S7-1.
11.
Vanti
,
F.
,
Pinelli
,
L.
,
Poli
,
F.
, and
Arnone
,
A.
(
2017
).
Aeroelastic investigation of turbine blade assemblies: Cluster system and mistuned rows
. In
European Conference on Turbomachinery Fluid dynamics and Thermodynamics
, pages
3
7
.
12.
Huang
,
W.
and
Li
,
L.
and
Lu
,
X.
and
Rao
,
H.
and
Jin
,
F.
(
2007
).
Finite Element Analysis of Dynamic Characteristics for Steam Turbine Interlocked Blades with Integral Shroud
In
Challenges of Power Engineering and Environment
, pages
303
308
.
13.
Lu
,
X.
and
Huang
,
W.
and Li,
L.
Huang
, S. (
2007
).
Damping Vibration Characteristics of Frictional Damping Structure in Steam Turbine Integrally Shrouded Blades
In
Challenges of Power Engineering and Environment
, pages
320
323
.
14.
Arnone
,
A.
and
Poli
,
F.
and
Schipani
,
C.
A method to assess flutter stability of complex modes
In
10ᵗʰ International Symposium on Unsteady Aerodynamics, Aeroacoustics and Aeroelasticity of Turbomachines (ISUAAAT)
. September 7–17,
Durham, NC, USA.
15.
Corral
,
R.
and
Beloki
,
J.
and
Calza
,
P.
and
Elliott
,
E.
(
2019
).
Flutter generation and control using mistuning in a turbine rotating rig
AIAA Journal
,
57
(
2
):
782
795
.
16.
Vanti
,
F.
,
Agnolucci
,
A.
,
Pinelli
,
L.
, and
Arnone
,
A.
(
2019
).
An integrated numerical procedure for flutter and forced response assessment of turbomachinery blade-rows
In
European Conference on Turbomachinery Fluid dynamics and Thermodynamics
, paper ETC2019-199
17.
Fransson
,
T.
(
2013
)
FUTURE Project Final Report, FTR-5-93
18.
Poli
,
F.
and
Pinelli
,
L.
(
2015
).
Aeroelastic stability analysis of a non-rotating annular turbine test rig: a comparison between a linearized and a non-linear computational method
In
22th International Congress on Sound and Vibration
.
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