Effect of free-stream turbulence on control of laminar separation bubbles using pulsed vortex generator jets: Direct numerical simulations

Shirzad Hosseinverdi, Hermann F. Fasel

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

3 Scopus citations

Abstract

Direct numerical simulations were employed to investigate the effects of free-stream turbulence on the control of laminar boundary-layer separation using pulsed vortex generator jets. Earlier research has shown that laminar separation can efficiently and effectively be controlled when an inviscid shear-layer instability is exploited. This paper addresses the question if such a control remains effective under free-flight conditions, which are characterized by free-stream turbulence. In the direct numerical simulations isotropic free-stream turbulence was introduced at the inflow boundary. For low free-stream turbulence levels and a blowing ratio of 0.6 the pulsed jets showed the same effectiveness as observed in earlier research with zero free-stream turbulence. When the free-stream turbulence intensity was increased to 3% the effectiveness of the pulsed jets slowly diminished. A proper orthogonal decomposition of the time-dependent data revealed that the dominant flow structures are two-dimensional for low to moderate free-stream turbulence levels. For 3% turbulence intensity the dominant structures were streamwise- "streaky" structures. Additional simulations with higher blowing ratios were carried out for 3% free-stream turbulence. When the blowing ratio was increased to 1.5 the separation length was reduced. For larger blowing ratios the separation length remained constant. For a blowing ratio of 2.5 the most energetic flow structures were predominantly two-dimensional.

Original languageEnglish (US)
Title of host publication51st AIAA Aerospace Sciences Meeting including the New Horizons Forum and Aerospace Exposition 2013
StatePublished - Aug 19 2013
Event51st AIAA Aerospace Sciences Meeting including the New Horizons Forum and Aerospace Exposition 2013 - Grapevine, TX, United States
Duration: Jan 7 2013Jan 10 2013

Publication series

Name51st AIAA Aerospace Sciences Meeting including the New Horizons Forum and Aerospace Exposition 2013

Other

Other51st AIAA Aerospace Sciences Meeting including the New Horizons Forum and Aerospace Exposition 2013
CountryUnited States
CityGrapevine, TX
Period1/7/131/10/13

ASJC Scopus subject areas

  • Space and Planetary Science
  • Aerospace Engineering

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    Hosseinverdi, S., & Fasel, H. F. (2013). Effect of free-stream turbulence on control of laminar separation bubbles using pulsed vortex generator jets: Direct numerical simulations. In 51st AIAA Aerospace Sciences Meeting including the New Horizons Forum and Aerospace Exposition 2013 (51st AIAA Aerospace Sciences Meeting including the New Horizons Forum and Aerospace Exposition 2013).