The present paper illustrates the results of an experimental campaign conducted in the Cavitating Pump Rotordynamic Test Facility (CPRTF) at ALTA S.p.A. aimed at characterizing the rotordynamic forces acting on two different whirling tapered-hub, variable-pitch axial inducers. The forces acting on the impeller have been measured by means of a rotating dynamometer mounted just behind the inducer. The roles of the imposed whirl motion of the rotor, flow coefficient, cavitation number, and liquid temperature have been investigated. The destabilizing role of cavitation has been confirmed. The experimental results are consistent with previous experimental campaigns documented by the open literature, including the former data published by Caltech researchers. The observed dependence of the tangential and normal components of the rotordynamic force on the whirl-to-rotational speed ratio does not follow the quadratic functional behavior often assumed in the open literature. Rotordynamic forces of large amplitude and destabilizing nature especially occur in the presence of cavitation, potentially compromising the stability of the pump operation.

References

References
1.
Ehrich
,
F.
, and
Childs
,
S. D.
, 1984, “
Self-Excited Vibrations in High Performance Turbomachinery
,”
Mech. Eng.
,
106
(
5
), pp.
66
79
.
2.
Hergt
,
P.
, and
Krieger
,
P.
, 1969, “
Radial Forces in Centrifugal Pumps With Guide Vanes
,”
Proc. Inst. Mech. Eng.
,
184
(
3N
), pp.
101
107
.
3.
Ohashi
,
H.
, and
Shoji
,
H.
, 1984, “
Lateral Fluid Forces Acting on a Whirling Centrifugal Impeller in Vaneless and Vaned Diffuser
,”
Proc. Workshop on Rotordynamic Instability Problems in High Performance Turbomachinery, NASA Conf. Publ.
2338
, pp.
109
122
.
4.
Jery
,
B.
, 1987, “
Experimental Study of Unsteady Hydrodynamic Force Matrices on Whirling Centrifugal Pump Impellers
,” Report No. 200.22.
5.
Franz
,
R. J.
, 1989, “
Experimental Investigation of the Effect of Cavitation on the Rotordynamic Forces on a Whirling Centrifugal Pump Impeller
,” Ph.D. thesis, California Institute of Technology, Pasadena, CA.
6.
Yoshida
,
Y.
,
Tsujimoto
,
Y.
,
Morimoto
,
G.
,
Nishida
,
H.
, and
Morii
,
S.
, 2003, “
Effects of Seal Geometry on Dynamic Impeller Fluid Forces and Moments
,”
ASME J. Fluids Eng.
,
125
, pp.
786
795
.
7.
Suzuki
,
T.
,
Prunieres
,
R.
,
Horiguchi
,
H.
,
Tsukiya
,
T.
,
Taenaka
,
Y.
, and
Tsujimoto
,
Y.
, 2006, “
Measurements of Rotordynamic Forces on an Artificial Heart Pump Impeller
,”
Proc. 23rd IAHR Symposium
, Yokohama, Japan.
8.
Bhattacharyya
,
A.
, 1994, “
Internal Flows and Force Matrices in Axial Flow Inducers
,” Ph.D. thesis, California Institute of Technology, Pasadena, CA.
9.
Rapposelli
,
E.
,
Cervone
,
A.
, and
d’Agostino
,
L.
, 2002, “
A New Cavitating Pump Rotordynamic Test Facility
,”
Proc. 38th AIAA/ASME/SAE/ASEE Joint Propulsion Conference
, Indianapolis, IN.
10.
d’Agostino
,
L.
,
Torre
,
L.
,
Pasini
,
A.
, and
Cervone
,
A.
, 2008, “
On the Preliminary Design and Noncavitating Performance of Tapered Axial Inducers
,”
ASME J. Fluids Eng.
,
130
(
11
),
111303
.
11.
d’Agostino
,
L.
,
Torre
,
L.
,
Pasini
,
A.
,
Baccarella
,
D.
,
Cervone
,
A.
, and
Milani
,
A.
, 2008, “
A Reduced Order Model for Preliminary Design and Performance Prediction of Tapered Inducers: Comparison With Numerical Simulations
,”
Proc. 44th AIAA/ASME/SAE/ASEE Joint Propulsion Conference
, Hartford, CT.
12.
Bhattacharyya
,
A.
,
Acosta
,
A. J.
,
Brennen
,
C. E.
, and
Caughey
,
T. K.
, 1997, “
Rotordynamic Forces in Cavitating Inducers
,”
ASME J. Fluids Eng.
,
199
(
4
), pp.
768
774
.
You do not currently have access to this content.