LES of active control using pulsed slots · LES of active control using pulsed slots J.-P. Laval...

Definition Parameters Results Conclusion

LES of active control using pulsed slots

J.-P. Laval

[email protected]

Laboratoire de Mecanique de Lille (LML), CNRSBlv Paul Langevin

59655 Villeneuve d’Ascq, FRANCE

November 24-25, 2011

J.-P. Laval GDR Controle Des Decollements, 24-25 Novembre 2011


Context

Numerical study on WALLTURB (smooth) bump with highlyresolved LES

Experiments on active control with a AVERT bump (with sharpedge and separation)

Numerical studies planned in ANR “SEPACODE”(with PPRIMEand PRISME)

Opportunity to perform ”quick” tests of old and new controlconfigurations



LES parameters

Configuration: AVERT bump (plate: -2, flap: -19)

Inlet Conditions: DNS of channel flow at Reτ = 617

Resolution: 1280×129×256 (∆x+max =19,∆y+

max =15,∆z+max =14)

Sub-grid Model: WALE (Nicoud et al, 1999)

Integration: 8 convective times (after convergence)

Code: Laval et al, JoT, 11(52) (2010) [Pulsed jets on WALLTURB bump]

(1/4 of meshes in each direction)



Resolution near separation point



Statistics: mean velocity



Statistics: Pressure Coefficient



Statistics: Friction Coefficient



Parameters

Parameters of control for few cases

Case type Xslot V maxslot αslot δx (δ+

x ) δz Freq. F(t) Flux(1) DC

00 no control - - - - - - - - -

01 1 spanwise slot 8.92 0.25 +90o 0.03 (25+) Lz =2π 10 Sinus ± 0.119% 0.5








09 1 spanwise slot 8.92 0.25 +90o 0.03 (25+) Lz =2π 2 Square + 0.092% 0.5

10 1 spanwise slot 8.92 0.25 +90o 0.03 (25+) Lz =2π 2 Random ± 0.049% -

11 8 slots 8.92 0.25 +90o 0.03 (25+) 0.40 2 Sinus ± 0.061% 0.5

12 8 slots 8.92 0.25 +90o 0.03 (25+) 0.50 2 Sinus ± 0.076% 0.5

(1) Flux of slots with respect to inlet flux of the channel (±: blowing & suction; + : blowing only)



Results: effect of frequency



Results: effect of position



Results: effect of blowing & suction



Results: effect of velocity



Results: spanwise length of slots



Coherent structures

Iso-value (Q=200) of Q = Ω2 − S2 (F=2).



Phase Averaged Velocity Vectors

Phase averaged velocity (F=1).



First conclusion

Interesting tool to start a parametric study

Not too expensive at fairly low Reynolds number

Few configurations could be tested using DNS

Allow any low order statistics (due to limited integration time)

Allow space time analysis of coherent structures

First results confirm benefit of pulsed jets in a given range offrequencies

References for numerical studies of flow control with the same code:

Laval et al, J. Turbulence, 11(52), 2010

Fournier et al, Int. J. Flow Control, 2(4), 2010



Additional materials : Spanwise length of slots


LES of active control using pulsed slots · LES of active control using pulsed slots J.-P. Laval...

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