A Three-Dimensional Time-Accurate Computational Fluid Dynamics Simulation of the Flow Field Inside a Vaneless Diffuser During Rotating Stall Conditions

Submitted by admin on Tue, 07/19/2016 - 18:48
TitleA Three-Dimensional Time-Accurate Computational Fluid Dynamics Simulation of the Flow Field Inside a Vaneless Diffuser During Rotating Stall Conditions
Publication TypeJournal Article
Year of Publication2017
AuthorsMarconcini M, Bianchini A, Checcucci M, Ferrara G, Arnone A, Ferrari L, Biliotti D, Rubino D T
JournalASME Journal of Turbomachinery
Volume139
Issue2
Pagination021001
Date Published09/2016
ISSN Number0889-504X
Accession NumberWOS:000395518900001
Other NumbersScopus 2-s2.0-84994218501
KeywordsCentrifugal Compressors, rotating stall, vaneless diffuser
Abstract
An accurate characterization of rotating stall in terms of inception modality, flow structures, and stabilizing force is one of the key goals for high-pressure centrifugal compressors. The unbalanced pressure field that is generated within the diffuser can be in fact connected to a non-negligible aerodynamic force and then to the onset of detrimental sub-synchronous vibrations which can prevent the machine from operating beyond this limit.
An inner comprehension on how the induced flow pattern in these conditions affects the performance of the impeller and its mechanical stability can therefore lead to the development of a more effective regulation system able to mitigate the effects of the phenomenon and extend the left-side margin of the operating curve.
In the present study, a 3D-unsteady CFD approach was applied to the simulation of a radial stage model including the impeller, the vaneless diffuser and the return channel. Simulations were carried out with the TRAF code of the University of Florence. The tested rotor was an industrial impeller operating at high peripheral Mach number, for which unique experimental pressure measurements, including the spatial reconstruction of the pressure field at the diffuser inlet, were available. The comparison between experiments and simulations showed a good matching and corroborated the CFD capabilities in correctly describing also some of the complex unsteady phenomena taking place in proximity of the left margin of the operating curve.
URLhttp://turbomachinery.asmedigitalcollection.asme.org/article.aspx?articleid=2551877
DOI10.1115/1.4034633
Refereed DesignationRefereed