Investigations of an airfoil at low Reynolds number conditions

C. Brehm, S. Mack, A. Gross, H. F. Fasel

Research output: Chapter in Book/Report/Conference proceedingConference contributionpeer-review

35 Scopus citations


The low-Reynolds number aerodynamics of airfoils that were designed for higher Reynolds numbers can be surprisingly different from what one might expect. The intricate interplay of separation and transition can substantially affect airfoil performance at lower than de-sign Reynolds number. We employed computational fluid dynamics for investigating the natural (uncontrolled) flow field around the NACA 643 - 618 airfoil at a chord Reynolds number of 64,000 for different angles of attack. Airfoil performance at moderate angles of attack is reduced considerably due to a massive trailing edge separation. At high angles of attack a leading edge separation bubble is formed which was found to transition the flow and reduce the trailing edge separation resulting in a lift recovery. We also investigated open-loop control by blowing and suction through a slot. We found that by exploiting hydrodynamic instability of the baseflow the control could be made more effective. The final objective is to develop closed-loop controllers for airfoils that will help recover the full size performance at lower model Reynolds-number conditions with minimal control effort.

Original languageEnglish
Title of host publication4th AIAA Flow Control Conference
StatePublished - 2008

Publication series

Name4th AIAA Flow Control Conference

ASJC Scopus subject areas

  • Fluid Flow and Transfer Processes
  • Control and Systems Engineering
  • Aerospace Engineering


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