Direct numerical simulations of laminar separation bubbles on a curved plate: Part 2 - Flow control using pulsed vortex generator jets

Wolfgang Balzer, Hermann F Fasel

Research output: Chapter in Book/Report/Conference proceedingConference contribution

3 Scopus citations

Abstract

Highly-accurate direct numerical simulations (DNS) are employed to investigate active flow control of laminar boundary layer separation by means of pulsed vortex generator jets (VGJs), i.e. by injecting fluid into the flow through a spanwise array of small holes. The uncontrolled flow configuration is represented by a laminar separation bubble developing on a curved-plate geometry modeling the convex suction-side curvature of the Pratt&Whitney "PackB" research blade. The simulation setup and uncontrolled flow results were presented in part I of the present paper. In this second part, particular focus is directed towards identifying the relevant physical mechanisms associated with VGJ control of low Reynolds number separation, as for example encountered in low-pressure turbine applications. The numerical results confirm findings of earlier flatplate simulations, which showed that the control effectiveness of pulsed VGJs can be explained by the fact that linear hydrodynamic instability mechanisms are exploited. When pulsing with frequencies to which the (uncontrolled) separated shear layer is naturally unstable, instability modes are shown to develop into large-scale, spanwise-coherent structures. These structures provide the necessary entrainment of high-momentum fluid causing a much sooner reattachment of the separated flow compared to the uncontrolled flow and consequently leading to a significant reduction in performance losses.

Original languageEnglish (US)
Title of host publicationProceedings of the ASME Turbo Expo
Volume6 B
DOIs
Publication statusPublished - 2013
EventASME Turbo Expo 2013: Turbine Technical Conference and Exposition, GT 2013 - San Antonio, Tx, United States
Duration: Jun 3 2013Jun 7 2013

Other

OtherASME Turbo Expo 2013: Turbine Technical Conference and Exposition, GT 2013
CountryUnited States
CitySan Antonio, Tx
Period6/3/136/7/13

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ASJC Scopus subject areas

  • Engineering(all)

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