### 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 language | English (US) |
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Title of host publication | 40th AIAA Fluid Dynamics Conference |

State | Published - 2010 |

Event | 40th AIAA Fluid Dynamics Conference - Chicago, IL, United States Duration: Jun 28 2010 → Jul 1 2010 |

### Other

Other | 40th AIAA Fluid Dynamics Conference |
---|---|

Country | United States |

City | Chicago, IL |

Period | 6/28/10 → 7/1/10 |

### Fingerprint

### ASJC Scopus subject areas

- Fluid Flow and Transfer Processes

### Cite this

*40th AIAA Fluid Dynamics Conference*[2010-4736]

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

Research output: Chapter in Book/Report/Conference proceeding › Conference contribution

*40th AIAA Fluid Dynamics Conference.*, 2010-4736, 40th AIAA Fluid Dynamics Conference, Chicago, IL, United States, 6/28/10.

}

TY - GEN

T1 - Numerical investigation of separation for airfoils at low Reynolds numbers

AU - Gross, A.

AU - Fasel, Hermann F

PY - 2010

Y1 - 2010

N2 - 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.

AB - 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.

UR - http://www.scopus.com/inward/record.url?scp=78649453284&partnerID=8YFLogxK

UR - http://www.scopus.com/inward/citedby.url?scp=78649453284&partnerID=8YFLogxK

M3 - Conference contribution

AN - SCOPUS:78649453284

SN - 9781617389221

BT - 40th AIAA Fluid Dynamics Conference

ER -