Publication detail

Proper Orthogonal Decomposition of Self-Induced Instabilities in Decelerated Swirling Flows and Their Mitigation Through Axial Water Injection

ŠTEFAN, D. RUDOLF, P. MUNTEAN, S. SUSAN-RESIGA, R.

Original Title

Proper Orthogonal Decomposition of Self-Induced Instabilities in Decelerated Swirling Flows and Their Mitigation Through Axial Water Injection

Type

journal article in Web of Science

Language

English

Original Abstract

The swirling flow exiting the runner of a hydraulic turbine is further decelerated in the discharge cone of the draft tube to convert the excess of dynamic pressure into static pressure. When the turbine is operated far from the best efficiency regime, particularly at part load, the decelerated swirling flow develops a self-induced instability with a precessing helical vortex and the associated severe pressure fluctuations. This phenomenon is investigated numerically in this paper, for a swirl apparatus configuration. The unsteady three-dimensional (3D) flow field is analyzed using a proper orthogonal decomposition (POD), and within this framework we examine the effectiveness of an axial jet injection for mitigating the flow instability. It is shown that a limited number of modes can be used to reconstruct the flow field. Moreover, POD enables to reveal influence of the jet injection on the individual modes of the flow and illustrates continuous suppression of the modes from higher-order modes to lower-order modes as the jet discharge increases. Application of POD offers new view for the future control effort aimed on vortex rope mitigation because spatiotemporal description of the flow is provided. Thereby, POD enables better focus of the jets or other flow control devices.

Keywords

helical vortex, POD, CFD, flow instability

Authors

ŠTEFAN, D.; RUDOLF, P.; MUNTEAN, S.; SUSAN-RESIGA, R.;

Released

1. 8. 2017

Publisher

ASME

ISBN

0098-2202

Periodical

JOURNAL OF FLUIDS ENGINEERING-TRANSACTIONS OF THE ASME

Year of study

139

Number

8

State

United States of America

Pages from

1

Pages to

25

Pages count

25

URL

http://fluidsengineering.asmedigitalcollection.asme.org/article.aspx?articleid=2612926

BibTex

@article{BUT136010,
  author="ŠTEFAN, D. and RUDOLF, P. and MUNTEAN, S. and SUSAN-RESIGA, R.",
  title="Proper Orthogonal Decomposition of Self-Induced Instabilities in Decelerated Swirling Flows and Their Mitigation Through Axial Water Injection",
  journal="JOURNAL OF FLUIDS ENGINEERING-TRANSACTIONS OF THE ASME",
  year="2017",
  volume="139",
  number="8",
  pages="1--25",
  doi="10.1115/1.4036244",
  issn="0098-2202",
  url="http://fluidsengineering.asmedigitalcollection.asme.org/article.aspx?articleid=2612926"
}