Numerical investigation of separation for airfoils at low Reynolds numbers

A. Gross, Hermann F Fasel

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

16 Citations (Scopus)

Abstract

The present study is concerned with the Aeromot 200S Super Ximango motor glider for which we built two 1:5 scale dynamically scaled models. For a two-dimensional section of its wing, which has a modified NACA 643-618 airfoil, we computed the unsteady time-dependent flow for two chord Reynolds numbers, 64,200 and 322,000. At Re=64,200, the wing tip Reynolds number at model takeoff speed, most of the turbulent energy spectrum can be captured using direct numerical simulations and turbulence modeling is not required. For α = 8.64deg laminar separation occurs near the maximum thickness resulting in a considerable performance loss. As the angle of attack is increased a leading edge bubble forms. The turbulent boundary layer downstream of the bubble is more resistant to separation resulting in a considerable performance recovery. For even higher angles of attack the leading edge bubble "bursts" and performance is once again lost. At Re=322,000, the model cruise Reynolds number based on mean aerodynamic chord, computer limitations prohibit direct numerical simulations and necessitate turbulence modeling. We employed filter-based Reynolds-averaged Navier-Stokes for simulations at an angle of attack of 13.2deg. The flow again separates near the maximum thickness location. In a separate simulation we show how performance can partially be recovered by harmonic blowing through a spanwise slot near the leading edge of the airfoil.

Original languageEnglish (US)
Title of host publication40th AIAA Fluid Dynamics Conference
StatePublished - 2010
Event40th AIAA Fluid Dynamics Conference - Chicago, IL, United States
Duration: Jun 28 2010Jul 1 2010

Other

Other40th AIAA Fluid Dynamics Conference
CountryUnited States
CityChicago, IL
Period6/28/107/1/10

Fingerprint

Angle of attack
Airfoils
Reynolds number
Direct numerical simulation
Turbulence
Gliders
Takeoff
Blow molding
Aerodynamics
Boundary layers
Recovery

ASJC Scopus subject areas

  • Fluid Flow and Transfer Processes

Cite this

Gross, A., & Fasel, H. F. (2010). Numerical investigation of separation for airfoils at low Reynolds numbers. In 40th AIAA Fluid Dynamics Conference [2010-4736]

Numerical investigation of separation for airfoils at low Reynolds numbers. / Gross, A.; Fasel, Hermann F.

40th AIAA Fluid Dynamics Conference. 2010. 2010-4736.

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

Gross, A & Fasel, HF 2010, Numerical investigation of separation for airfoils at low Reynolds numbers. in 40th AIAA Fluid Dynamics Conference., 2010-4736, 40th AIAA Fluid Dynamics Conference, Chicago, IL, United States, 6/28/10.
Gross A, Fasel HF. Numerical investigation of separation for airfoils at low Reynolds numbers. In 40th AIAA Fluid Dynamics Conference. 2010. 2010-4736
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