The impact mode coupling between impeller blades and the disk backwall has on the forced response amplitude of impeller blades is assessed. The assessments focus on the forced response of two splitter blade modes to a variety of representative boundary conditions and unsteady loadings. The forcing function is the synchronous unsteady loading generated by the impeller–diffuser interaction at resonance. The results indicate that modal coupling of blade- and disk-dominant modes renders the forced response highly sensitive to small variations in airfoil and disk backwall thickness. As a complement, a reduced-order model based on the forced response of a two mass–spring system is used to elucidate the physical interaction of modal coupling. The practical implication of this finding is that a forced response issue with an impeller blade cannot be addressed adequately by stiffening the structure, such as thickening the blade or disk. Thus, appropriate measures need to be taken to avoid potential blade–disk mode couplings within the manufacturing tolerances of the part.

References

References
1.
Murray
,
N.
, and
Tan
,
C. S.
,
2004
, “
Aeromechanic Implications Associated With Time-Average Effect of Impeller-Diffuser Interaction on Centrifugal Compressor Performance
,”
9th National Turbine Engine High Cycle Fatigue Conference
, Pinehurst, NC, Mar.
16
19
.
2.
Smythe
,
C.
,
Liu
,
J.
, and
Tan
,
C. S.
,
2005
, “
Forced Response Predictions in Modern Centrifugal Compressor Design
,”
10th National Turbine Engine High Cycle Fatigue Conference
, New Orleans, LA, Mar. Mar.
8
11
.
3.
Gould
,
K.
,
2007
, “
Characterization of Unsteady Impeller-Blade Loading in a Centrifugal Compressor With a Discrete-Passage Diffuser
,”
ASME
Paper No. GT2007-28002.
4.
Lusardi
,
C.
,
2012
, “
Characterization of Unsteady Loading Due to Impeller Diffuser Interaction in Centrifugal Compressors
,” M.S. thesis, Massachusetts Institute of Technology, Cambridge, MA.
5.
Borm
,
O.
, and
Kau
,
H.-P.
, “
Unsteady Aerodynamics of a Centrifugal Compressor Stage: Validation of Two Different CFD Solvers
,”
ASME
Paper No. GT2012-69636.
6.
Pierre
,
C.
,
1988
, “
Mode Localization and Eigenvalue Loci Veering Phenomena in Disorder Structures
,”
J. Sound Vib.
,
126
(
3
), pp.
485
502
.
7.
Bladh
,
J.
,
2001
, “
Efficient Predictions of the Vibratory Response of Mistuned Bladed Disks by Reduced Order Modeling
,” Ph.D. thesis, University of Michigan, Ann Arbor, MI.
8.
du Bois
,
J. L.
,
Lieven
,
N. A. J.
, and
Adhikari
,
S.
,
2009
, “
Localization and Curve Veering: A Different Perspective on Modal Interactions
,” 27th Conference and Exposition on. Structural Dynamics (
IMAC XXVII
), Orlando, FL, Feb. 9-12, pp.
29
39
.
9.
Shum
,
Y. K. P.
,
Tan
,
C. S.
, and
Cumpsty
,
N. A.
,
2000
, “
Impeller-Diffuser Interaction in a Centrifugal Compressor
,”
ASME J. Turbomach.
,
122
(
4
), pp.
777
786
.
10.
Ziegler
,
K. U.
,
Gallus
,
H. E.
, and
Niehuis
,
R.
,
2003
, “
A Study on Impeller-Diffuser Interaction: Part I—Influence on the Performance
,”
ASME J. Turbomach.
,
125
(
1
), pp.
173
182
.
11.
Leng
,
Y.
, and
Fleeter
,
S.
,
2014
, “
Analytical Modeling of the Unsteady Wave Propagation in the Vaneless Space of a Low Speed Centrifugal Compressor
,”
22nd International Compressor Engineering Conference at Purdue
, West Lafayette, IN, July 14–17, 2014.
12.
ANSYS Academic Research
, Help System, 5.3, Solving a Cyclic Symmetry Analysis, Release 14.0 Edition, ANSYS, Inc., Canonsburg, PA.
13.
Singh
,
M. P.
,
Vargo
,
J. J.
,
Schiffer
,
D. M.
, and
Dello
,
J. D.
,
1988
, “
Safe Diagram—A Design and Reliability Tool for Turbine Blading
,”
17th Turbomachinery Symposium
, Dallas, TX, Nov. 8–10, Texas A&M University Press, College Station, TX.
14.
Snyder
,
L. E.
, and
Burns
,
D. W.
,
1998
, “
Forced Vibration and Flutter Design Methodology
,”
AGARD Manual on Aeroelasticity in Axial-Flow Turbomachines
,
NATO
,
Washington, DC
.
15.
Ramakrishnan
,
K.
,
Richards
,
S. K.
,
Moyroud
,
F.
, and
Michelassi
,
V.
,
2011
, “
Multi-Blade Row Interactions in a Low Pressure Ratio Centrifugal Compressor Stage With a Vaned Diffuser
,”
ASME
Paper No. GT2011-45932.
16.
Inman
,
D. J.
,
1994
,
Engineering Vibration
,
Prentice-Hall
,
Englewood Cliffs, NJ
.
17.
Kammerer
,
A.
,
2009
, “
Experimental Study of Impeller Blade Vibration During Resonance—Part II: Blade Damping
,”
ASME J. Eng. Gas Turbines Power
,
131
(
2
), p.
022509
.
18.
Walter
,
R.
,
2011
, “
Provision and Discussion of Impeller FEM Model, Light Probe Measurements
,” personal communication.
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