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Research Papers: Flows in Complex Systems

Experimental Characterization of the Rotordynamic Forces on Space Rocket Axial Inducers

[+] Author and Article Information
Lucio Torre, Angelo Pasini

Angelo Cervone

 Alta S.p.A., Via Gherardesca 5, 56121 Pisa, Italya.cervone@alta-space.com

Luca d’Agostino

 Professor Pisa University, Via G. Caruso 8, 56122 Pisa, Italyluca.dagostino@ing.unipi.it

J. Fluids Eng 133(10), 101102 (Oct 05, 2011) (12 pages) doi:10.1115/1.4005100 History: Received November 30, 2010; Accepted September 09, 2011; Published October 05, 2011; Online October 05, 2011

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.

Copyright © 2011 by American Society of Mechanical Engineers
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Figures

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Figure 4

Geometrical and operational parameters of the DAPAMITO4 inducer

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Figure 3

Geometrical and operational parameters of the DAPAMITO3 inducer

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Figure 2

Rendering of the test chamber assembly in the rotordynamic configuration (CPRTF) used for the test campaign reported in the present paper

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Figure 18

Frames of the DAPAMITO3 inducer taken from a high speed movie (600 fps) corresponding to a complete whirl orbit (Φ = 0.044, σ = 0.094, T = 19.8°C, ω/Ω = +0.3)

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Figure 19

Effect of the fluid temperature T on the normal (FN*) and tangential (FT*) components of the rotordynamic force in the DAPAMITO4 inducer under cavitating regime

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Figure 20

Effect of the fluid temperature T on the intensity (|FR*|) and phase (φ) of the rotordynamic force in the DAPAMITO4 inducer under cavitating regime

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Figure 5

Schematic representation of the rotordynamic forces in the laboratory and rotating reference frames

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Figure 6

Test matrices for the DAPAMITO3 (left) and the DAPAMITO4 (right) inducers

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Figure 7

Noncavitating performance and hydraulic efficiency of the DAPAMITO3 (top) and DAPAMITO4 (bottom) inducers at different water temperatures

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Figure 1

The Cavitating Pump Rotordynamic Test Facility (left) and a cut-off drawing of the CPRTF test section (right), where the orange component is the rotating dynamometer

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Figure 8

Schematic of the decomposition of the rotordynamic force in its components normal (F→N) and tangent (F→T) to the whirl orbit. The convention adopted for the phase angle (φ) between the rotordynamic force and the eccentricity is shown. Colored areas refer to the different stability regions for positive (left) and negative (right) whirl ratio.

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Figure 9

Effect of the eccentricity ɛ on the intensity (|FR*|) and phase (φ) of the rotordynamic force for the DAPAMITO3 inducer

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Figure 10

Effect of the flow coefficient Φ on the normal (FN*) and tangential (FT*) components of the rotordynamic force in the DAPAMITO4 inducer under noncavitating regime

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Figure 11

Effect of the flow coefficient Φ on the intensity (|FR*|) and phase (φ) of the rotordynamic force in the DAPAMITO4 inducer under noncavitating regime

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Figure 12

Effect of the fluid temperature T on the intensity (|FR*|) and phase (φ) of the rotordynamic force in the DAPAMITO4 inducer under noncavitating regime

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Figure 13

Effect of the cavitation number σ on the normal (FN*) and tangential (FT*) components of the rotordynamic force in the DAPAMITO4 inducer: cold tests at Φ = 0.044

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Figure 14

Effect of the cavitation number σ on the intensity (|FR*|) and phase (φ) of the rotordynamic force in the DAPAMITO4 inducer: cold tests at Φ = 0.044

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Figure 15

Effect of the cavitation number σ on the normal (FN*) and tangential (FT*) components of the rotordynamic force in the DAPAMITO4 inducer: cold tests at Φ = 0.029

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Figure 16

Effect of the cavitation number σ on the intensity (|FR*|) and phase (φ) of the rotordynamic force in the DAPAMITO4 inducer: cold tests at Φ = 0.029

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Figure 17

Effect of the cavitation number σ on the intensity (|FR*|) and phase (φ) of the rotordynamic force in the DAPAMITO3 inducer: cold tests at Φ = 0.044

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