This paper investigates the linearized dynamics of three-dimensional bubbly cavitating flows in helical inducers. The purpose is to understand the impact of the bubble response on the radial and tangential rotordynamic forces exerted by the fluid on the rotor and stator stages of whirling turbomachines under cavitating conditions. The flow in the inducer annulus is modeled as a homogeneous inviscid mixture, containing vapor bubbles with a small amount of noncondensable gas. The effects of several contributions to the damping of the bubble dynamics are included in the model. The governing equations of the inducer flow are written in “body-fitted” orthonormal helical Lagrangian coordinates, linearized for small-amplitude perturbations about the mean flow, and solved by modal decomposition. The whirl excitation generates finite-speed propagation and resonance phenomena in the two-phase flow within the inducer. These, in turn, lead to a complex dependence of the lateral rotordynamic fluid forces on the excitation frequency, the void fraction, the average size of the cavitation bubbles, and the turbopump operating conditions (including, rotational speed, geometry, flow coefficient and cavitation number). Under cavitating conditions the dynamic response of the bubbles induces major deviations from the noncavitating flow solutions, especially when the noncondensable gas content of the bubbles is small and thermal effects on the bubble dynamics are negligible. Then, the quadratic dependence of rotordynamic fluid forces on the whirl speed, typical of cavitation-free operation, is replaced by a more complex behavior characterized by the presence of different regimes where, depending on the whirl frequency, the fluid forces have either a stabilizing or a destabilizing effect on the inducer motion. Results are presented to illustrate the influence of the relevant flow parameters.
Skip Nav Destination
Article navigation
December 1998
Research Papers
A Three-Dimensional Analysis of Rotordynamic Forces on Whirling and Cavitating Helical Inducers
Luca d’Agostino,
Luca d’Agostino
Universita` degli Studi di Pisa, Pisa, Italy
Search for other works by this author on:
Fabrizio d’Auria,
Fabrizio d’Auria
California Institute of Technology, Pasadena, CA 91125
Search for other works by this author on:
Christopher E. Brennen
Christopher E. Brennen
Division of Engineering and Applied Science, California Institute of Technology, Pasadena, CA 91125
Search for other works by this author on:
Luca d’Agostino
Universita` degli Studi di Pisa, Pisa, Italy
Fabrizio d’Auria
California Institute of Technology, Pasadena, CA 91125
Christopher E. Brennen
Division of Engineering and Applied Science, California Institute of Technology, Pasadena, CA 91125
J. Fluids Eng. Dec 1998, 120(4): 698-704 (7 pages)
Published Online: December 1, 1998
Article history
Received:
January 21, 1998
Revised:
May 5, 1998
Online:
December 4, 2007
Citation
d’Agostino, L., d’Auria, F., and Brennen, C. E. (December 1, 1998). "A Three-Dimensional Analysis of Rotordynamic Forces on Whirling and Cavitating Helical Inducers." ASME. J. Fluids Eng. December 1998; 120(4): 698–704. https://doi.org/10.1115/1.2820726
Download citation file:
Get Email Alerts
Experimental Investigation of the Effect of Rake on a Bluff Body Equipped With a Diffuser
J. Fluids Eng (April 2025)
Related Articles
Analysis of Thermal Effects in a Cavitating Orifice Using Rayleigh Equation and Experiments
J. Eng. Gas Turbines Power (September,2010)
Theoretical and Experimental Comparisons for Damping Coefficients of a Short-Length Open-End Squeeze Film Damper
J. Eng. Gas Turbines Power (October,1996)
Theory Versus Experiment for the Rotordynamic Characteristics of a High Pressure Honeycomb Annular Gas Seal at Eccentric Positions
J. Tribol (April,2003)
Dynamic Response of Ducted Bubbly Flows to Turbomachinery-Induced Perturbations
J. Fluids Eng (September,1996)
Related Proceedings Papers
Related Chapters
Study on the Hybrid Method of CFD and Bubble Dynamics for Marine Propeller Cavitation Noise Prediction
Proceedings of the 10th International Symposium on Cavitation (CAV2018)
Numerical Investigation of the Dynamics of Pressure Loading on a Solid Boundary from a Collapsing Cavitation Bubble
Proceedings of the 10th International Symposium on Cavitation (CAV2018)
Completing the Picture
Air Engines: The History, Science, and Reality of the Perfect Engine