Open-loop flow-control investigation for airfoils at low reynolds numbers

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

Research output: Contribution to journalArticlepeer-review

6 Scopus citations


Within the scope of a flight research project involving dynamically scaled models, active flow control was investigated for a modified NACA 64 3-618 airfoil. At low-Reynolds-number conditions, the aerodynamic performance of the modifiedNACA 643-618 airfoil is considerably reduced by flow separation. Computational-fluiddynamics simulations of the natural (uncontrolled) and controlled flow were carried out and provide the basis for a detailed analysis of the underlying physical mechanisms. The simulation results for the natural uncontrolled flow compare well with wind-tunnel measurements. Simulations and experiments show a large trailing-edge separation at lowangles of attackand a leading-edge separationbubble at highangles of attack.Tocontrol the laminar separationand improve the overall performance of the airfoil at the low-Reynolds-number conditions, time-periodic blowing and suction through a spanwise slot is employed. A strong dependence of the effectiveness of the active flow control on the forcing parameters, such as forcing frequency and forcing slot location, is found. In addition, linear stability analysis is employed to identify the instability mechanisms that are responsible for the effectiveness of the flow-control approach.

Original languageEnglish
Pages (from-to)1843-1860
Number of pages18
JournalAIAA Journal
Issue number8
StatePublished - Aug 2013

Bibliographical note

Funding Information:
This work was funded by the U.S. Air Force Office of Scientific Research under grant FA9550-05-1-0166, and by NASA under grant NNl07AA40C through the Small Business Technology Transfer Program (STTR) with Advanced Ceramics Research.

ASJC Scopus subject areas

  • Aerospace Engineering


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