1 26.01.16

www.kit.eduKIT – Die Forschungsuniversität in der Helmholtz-Gemeinschaft

Institute of Fluid Mechanics (ISTM) KIT, Linné Flow Centre KTH

RANS Investigation of Blowing and Suction for Turbulent Flow Control on a Wing Section

G. Fahland, D. Gatti, B. Frohnapfel & A. StrohM. Atzori, R. Vinuesa & P. Schlatter

2 01.02.2019

Boundary Layer Control Scheme

Uniform Suction/Blowing

Active Control Scheme

Low Blowing Intensity

(0.025-2% of U∞)

Flat plat: 80% drag reduction

Developing Boundary Layer

Blowing δ ↑, � ↓

Suction δ ↓, � ↑

[A. Stroh, Diss. 2015]

3 01.02.2019

Motivation / Objective

Airfoil requirements

Lift

Efficiency

Momentum

Stall properties

Control surfaces

��

��ℎ

…

Means

Shape

Flaps, etc.

Boundary Layer Control (BLC)

?

4 01.02.2019

General

RANS, low-��, incompressible

OpenFOAM SIMPLE FOAM

��-SST

Methodology

Laminar Flow + Tripping �� � 0.1 Source for �

Fully turbulent flow

��-SST � � 0, � ��

Same effect as LM-model

Fast convergence

No natural transition

Caution: Laminar separation bubble

��-SSTLM

Transitional model

All transition modes applicable

for airfoils

Slow/No convergence

5 01.02.2019

Different Airfoils (7)

Different ��

Automated mesh generation

Methodology - Mesh

Structured meshes (blockmesh)

�40 Meshes

6 01.02.2019

Validation

Mesh convergence study

XFOIL

Experimental data:

ClarkY (Fukagata Lab, Keio University)

Naca23012 (IAG, University Stuttgart)

DNS/LES data:

Naca4412 (Linné Flow Centre, KTH)

7 01.02.2019

Validation – DNS/LES data

� � � ∆ to reference

LES (KTH) 0,842 0,0202 41,7 -6,2%

RANS 0,829 0,0204 40,6 -6,6%

� ��

12

!"

Naca4412, �� � 2 · 10$, % � 5°, ()*+ � 0.1%!"

Reference

Blowing

8 01.02.2019

Aspects of Results

%

�� � !"

-

()*+

.)*+ )*+

Using BLC and Geometry Design complementary

9 01.02.2019

% � 5°

Blowing PS

� ��

12

!"

% � 9°

Wall shear stress 01: 2-Dependency

Blowing PS

Naca4412 KTH-config, �� � 4 · 10$

10 01.02.2019

Polar: 2 - Dependency

� �45

12

!"6 7

� �4*

12

!"6 7

Reference

Blowing PS

Naca4412 KTH-config, �� � 4 · 10$

11 01.02.2019

89-Dependency

:Φ � Φ

Φ�<�

� =>? � =>@

[Aviation History Museum][fatlion.com]

Blowing PS

Suction SS

Blowing SS

Naca4412 KTH-config, % � 5°

12 01.02.2019

Beneficial Blowing SS possible?

What do we need?

Natural turbulent BL

Fixed Transition Position

Constant � Stratford pressure gradient

/

13 01.02.2019

Beneficial Blowing SS possible?

Stratford pressure gradient

AH80-136

AH80-136-V3

14 01.02.2019

Beneficial Blowing SS possible?

�� � 10B

Launch/Approach

AH80-136: Reference

AH80-136-V3: Reference

Cruise

AH80-136-V3: Blowing SS

3.5% drag reduction

15 01.02.2019

Conclusion / Lookout

Summary:

Beneficial in General:

Blowing for higher ��

Blowing PS for low �

Suction SS for high �

Beneficial Blowing-on-SS-Setup also possible

Next steps of Interest:

Higher �� and ��ℎ

More Airfoil types

Transonic (negatively S-shaped Camber-Line)

Airfoils with Flaps/Slats

Airfoil geometry Matching BLC

Unsteady Stall Assessment

Unfavorable

Suction for higher ��

Blowing SS

Suction PS

16 01.02.2019

Varied Parameters

Parameterstudieα [°] -3 .. 12

Re 1e5 .. 2e7

Airfoil Naca4412, Clark-Y, Naca23012,

AH80-136

General Geometry Camber Naca5412, Naca6412

Thickness Naca4409, Naca4415

Flow Rate CDEF

[%G"]0.025 .. 2

Configurations Literature configurations KTH

Reder

Fukagata

Gersten

Enhancements Stratford Blowing

Combined SS-Suction + PS-

Blowing

17 01.02.2019

Methodology – Mesh Generation

Matlab workflow:1. Assessement of mesh requirements

with XFOIL

• �HIJ ℎHKL: NHKLO � 1

• PQ�KRH � ST:U , % � 5°V

• ℎ�� � S :U x � �� , % � 5°

2. Meshing with gmsh

3. Transform to OpenFOAM

4. Generating control sets for transition

handling

� � 0

� X 0

��

ℎ��

1%

18 01.02.2019

Validation – Experimental Data Naca23012

0,000 0,005 0,010 0,015 0,020

-0,2

0

0,2

0,4

0,6

0,8

1

1,2

1,4

cd

cl

Daten Stuttgarter Profilkatalog

Daten xfoil n_crit=13

Tripping ohne Turbulenzkontrolle

Tripping mit Turbulenzkontrolle

-5 0 5 10 15

α

cl

0 0,5 1

xtr/chord

Polarendiagramm Re = 1.5M

19 01.02.2019 Georg Fahland – Beeinflussung der turbulenten Grenzschicht an Flügelprofilen

mittels homogenem Ausblasen und Absaugen

Agenda

1. Motivation/Objective

2. Methodology and Validation

3. Results:

• %- dependency

• ��- dependency

• intensity- dependency

• Influence of configurations