Effect of an axial jet on aircraft wake...

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Work performed with the support from EC FP6 – “FAR-Wake” Effect of an axial jet on aircraft wake vortices D. Marles, P. Margaris, I. Gursul University of Bath Department of Mechanical Engineering

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Page 1: Effect of an axial jet on aircraft wake vorticesfar-wake.irphe.univ-mrs.fr/IMG/workshop/PDF/FWW_24_Gursul.pdf · Effect of an axial jet on aircraft wake vortices D. Marles, P. Margaris,

Work performed with the support from EC FP6 – “FAR-Wake”

Effect of an axial jet on aircraft wake vortices

D. Marles, P. Margaris, I. Gursul

University of BathDepartment of Mechanical Engineering

Page 2: Effect of an axial jet on aircraft wake vorticesfar-wake.irphe.univ-mrs.fr/IMG/workshop/PDF/FWW_24_Gursul.pdf · Effect of an axial jet on aircraft wake vortices D. Marles, P. Margaris,

Outline

• Single vortex / jet interaction• Main parameters:

R ratio of jet to vortex strengthh/dj jet-to-vortex distanceΓ/ν Reynolds numberαj jet inclination (take-off and

landing phases)

• Vortex pair / jet interaction• Effect on vortex merging• Additional parameter: Γt/ Γf

• Pulsed jets• Simulation of pulsed engine jets • Small flow control jets

Experiments in Fluids 2008

Physics of Fluids 2008

Page 3: Effect of an axial jet on aircraft wake vorticesfar-wake.irphe.univ-mrs.fr/IMG/workshop/PDF/FWW_24_Gursul.pdf · Effect of an axial jet on aircraft wake vortices D. Marles, P. Margaris,

Single vortex / jet interaction

Laser Unit- PIV (Nd-YAG)- Flow Vis. (Argon Ion)

U∞

Laser Sheet(Cross-flow)

Experimental Rig - Wing- Jet

Water tunnel

PIV Camera

PIV Laser Unit(Nd-Yag)

Laser Sheet(Cross-Flow)

U∞

Experimental Rig- Wing- Jet

Wind tunnel

• Wind and water tunnel

• Generic wings and nozzles

• PIV and flow visualization

Page 4: Effect of an axial jet on aircraft wake vorticesfar-wake.irphe.univ-mrs.fr/IMG/workshop/PDF/FWW_24_Gursul.pdf · Effect of an axial jet on aircraft wake vortices D. Marles, P. Margaris,

2

)(Γ

−= ∞

ρρ jjjj AUUU

R

• jet-to-vortex distance (h/dj)

• ratio of jet to vortex strength (R)

Main Parameters

cruise R ≅ 1T-O R ≅ 4 – 6

h/dj

R

0 2 4 6 8 10 120

1

2

3

4

5

6

7

8

9

10Water TunnelLarge Wind TunnelOpen Jet Wind TunnelA330-300B737-500Brunet, Garnier & JacquinWang & ZamanJacquin & Garnier

C

C

Single vortex / jet interaction

• jet inclination (αj)

• Reynolds number (Γ/ν)

Page 5: Effect of an axial jet on aircraft wake vorticesfar-wake.irphe.univ-mrs.fr/IMG/workshop/PDF/FWW_24_Gursul.pdf · Effect of an axial jet on aircraft wake vortices D. Marles, P. Margaris,

x/b = 0.35 x/b = 1.75

h/dj = 6.7 h/dj = 6.7

Flow Visualization

only jet visualised

h/dj = 4 h/dj = 4

Jet wrapped around the vortex

Jet ingested into the vortex

Page 6: Effect of an axial jet on aircraft wake vorticesfar-wake.irphe.univ-mrs.fr/IMG/workshop/PDF/FWW_24_Gursul.pdf · Effect of an axial jet on aircraft wake vortices D. Marles, P. Margaris,

Effect of jet-to-vortex distance (x/b=0.35)

y/dj

z/d j

-8 -6 -4 -2 0 2 4 6-8

-6

-4

-2

0

2

4

6

y/dj

z/d j

-8 -6 -4 -2 0 2 4 6-8

-6

-4

-2

0

2

4

6

y/dj

z/d j

-8 -6 -4 -2 0 2 4 6-8

-6

-4

-2

0

2

4

6

std(%)1815129630

h/dj = 6.7 h/dj = 4.0 h/dj = 2.7

PIV Measurements – Turbulence

Downstream evolution (h/dj=4) x/b = 0.35

/d

z/d j

-8 -6 -4 -2 0 2 4 6-8

-6

-4

-2

0

2

4

6

/d

z/d j

-8 -6 -4 -2 0 2 4 6-8

-6

-4

-2

0

2

4

6

/d

z/d j

-8 -6 -4 -2 0 2 4 6-8

-6

-4

-2

0

2

4

6

std(%)1815129630

x/b = 0.70 x/b = 1.05

Page 7: Effect of an axial jet on aircraft wake vorticesfar-wake.irphe.univ-mrs.fr/IMG/workshop/PDF/FWW_24_Gursul.pdf · Effect of an axial jet on aircraft wake vortices D. Marles, P. Margaris,

y/dj

z/d j

-8 -6 -4 -2 0 2 4 6-8

-6

-4

-2

0

2

4

6

y/dj

z/d j

-8 -6 -4 -2 0 2 4 6-8

-6

-4

-2

0

2

4

6

y/dj

z/d j

-8 -6 -4 -2 0 2 4 6-8

-6

-4

-2

0

2

4

6

y/dj

z/d j

-8 -6 -4 -2 0 2 4 6-8

-6

-4

-2

0

2

4

6

|U|/U00.30.250.20.150.10.050

ReΓ = 5,500h/dj = 4x/b = 1.05

Effect of R: cross-flow velocity magnitude

Uj = 0

R = 0.34

R = 0.13

R = 0.78

PIV Measurements – Time-averaged flow

|U|/U∞

Effect of wandering?

Page 8: Effect of an axial jet on aircraft wake vorticesfar-wake.irphe.univ-mrs.fr/IMG/workshop/PDF/FWW_24_Gursul.pdf · Effect of an axial jet on aircraft wake vortices D. Marles, P. Margaris,

Single vortex / jet interaction

y/dj

z/d j

-8 -6 -4 -2 0 2 4 6-8

-6

-4

-2

0

2

4

6

y/dj

z/d j

-8 -6 -4 -2 0 2 4 6-8

-6

-4

-2

0

2

4

6y/dj

z/d j

-8 -6 -4 -2 0 2 4 6-8

-6

-4

-2

0

2

4

6

y/dj

z/d j

-8 -6 -4 -2 0 2 4 6-8

-6

-4

-2

0

2

4

6

Time-averaged Instantaneous Vortex wanderingN

o je

tW

ith je

t

Vortex cross-flow velocity decreases (both in time-averaged and instantaneous) while wandering increase.

Page 9: Effect of an axial jet on aircraft wake vorticesfar-wake.irphe.univ-mrs.fr/IMG/workshop/PDF/FWW_24_Gursul.pdf · Effect of an axial jet on aircraft wake vortices D. Marles, P. Margaris,

• Jet turbulence can wrap around the vortex or get ingested into the vortex• Turbulence ingestion leads to decreasing cross-flow velocities (both in time-averaged and instantaneous sense)

PIV advantage over point measurements: removes the vortex wandering effect which affects the time-averaged measurements.

• Faster ingestion with decreasing jet-to-vortex distance and increasing jet strength

Potential for flap-edge vortices, due to their small distance from the engine jet.

• No noticeable differences were found within the Reynolds number range tested• The effect is negligible when the jet is blowing at an angle to the freestream

and away from the vortex such as during take-off

Summary

Single vortex / jet interaction

αj > 0: little effect(jet turbulence away from vortex)

αj < 0: maximum vortex velocity decreases(jet turbulence blown into vortex)unrealistic case, but useful for flow control purposes

Page 10: Effect of an axial jet on aircraft wake vorticesfar-wake.irphe.univ-mrs.fr/IMG/workshop/PDF/FWW_24_Gursul.pdf · Effect of an axial jet on aircraft wake vortices D. Marles, P. Margaris,

Vortex pair / jet interaction

ΓTip/ Γ Flap = 0.65, 1.0, 1.54

hv c

s

Water level

Uj

hj

U∞

zy x

h

Flap vortex

Tip vortex

Wing-tip vortex generator

Flap-edge vortex generator

U∞

Page 11: Effect of an axial jet on aircraft wake vorticesfar-wake.irphe.univ-mrs.fr/IMG/workshop/PDF/FWW_24_Gursul.pdf · Effect of an axial jet on aircraft wake vortices D. Marles, P. Margaris,

Experimental Setup

III

II

I

Configuration

Aircraft with 4 engines

Aircraft with 4 engines

Aircraft with 2 engines

Aircraft Configuration

ΓFlap ΓTip

ΓFlap ΓTip

Outboard Engine

ΓFlapΓTip

Outboard Engine

Jet Configurations

Page 12: Effect of an axial jet on aircraft wake vorticesfar-wake.irphe.univ-mrs.fr/IMG/workshop/PDF/FWW_24_Gursul.pdf · Effect of an axial jet on aircraft wake vortices D. Marles, P. Margaris,

Flow Visualisation – Jet Inboard of Flap

Tip

Flap

ΓFlap/ Γ Tip = 1.0

Tip

Flap

Vortex Pair Rotation

Tip

Flap

Increasing Downstream Distance

Jet

x/c = 4 x/c = 12 x/c = 24

Tip

FlapTip

Flap

Flap

Tip

Uj/U

∞=

0U

j/U∞

= 2

Flap

Tip

0.75c0.6c

ΓFlap ΓTip

Page 13: Effect of an axial jet on aircraft wake vorticesfar-wake.irphe.univ-mrs.fr/IMG/workshop/PDF/FWW_24_Gursul.pdf · Effect of an axial jet on aircraft wake vortices D. Marles, P. Margaris,

Tip

Flap

Flow Visualisation – Jet Vertically Below FlapΓFlap/ Γ Tip = 1.0

Tip

Flap

Jet

Uj/U

∞=

0U

j/U∞

= 2

x/c = 4 x/c = 12 x/c = 24

Tip

Flap Tip

Flap

Tip

Flap

Vortex Pair Rotation

Tip

Flap

Increasing Downstream Distance

0.75c

0.6c ΓFlap ΓTip

Page 14: Effect of an axial jet on aircraft wake vorticesfar-wake.irphe.univ-mrs.fr/IMG/workshop/PDF/FWW_24_Gursul.pdf · Effect of an axial jet on aircraft wake vortices D. Marles, P. Margaris,

y/c

z/c

-1.4 -1.2 -1 -0.8 -0.6 -0.4 -0.2 0 0.2 0.4 0.6 0.8-1

-0.8

-0.6

-0.4

-0.2

0

0.2

0.4

0.6

0.8

1

1.2

Effect of Jet Flux – Contours of Vorticity

Uj/U∞ = 0Flap

Tip

y/c

z/c

-1.4 -1.2 -1 -0.8 -0.6 -0.4 -0.2 0 0.2 0.4 0.6 0.8-1

-0.8

-0.6

-0.4

-0.2

0

0.2

0.4

0.6

0.8

1

1.2

Jet Inboard of Flap, x/c = 16

Uj/U∞ = 2.8

Vortex Pair Rotation

y/c

z/c

-1.4 -1.2 -1 -0.8 -0.6 -0.4 -0.2 0 0.2 0.4 0.6 0.8-1

-0.8

-0.6

-0.4

-0.2

0

0.2

0.4

0.6

0.8

1

1.2

y/c

z/c

-1.4 -1.2 -1 -0.8 -0.6 -0.4 -0.2 0 0.2 0.4 0.6 0.8-1

-0.8

-0.6

-0.4

-0.2

0

0.2

0.4

0.6

0.8

1

1.2

Flap

Tip

Jet Vertically Below Flap, x/c = 8

Uj/U∞ = 0

Uj/U∞ = 2.8

Vortex Pair Rotation

Flap

Tip

Tip

Flap

ΓFlap/ Γ Tip = 1.0

Page 15: Effect of an axial jet on aircraft wake vorticesfar-wake.irphe.univ-mrs.fr/IMG/workshop/PDF/FWW_24_Gursul.pdf · Effect of an axial jet on aircraft wake vortices D. Marles, P. Margaris,

x/c

h/h v

0 5 10 15 20 250

0.2

0.4

0.6

0.8

1

1.2

x/c

θ

0 5 10 15 20 250

50

100

150

200

250

300

350

400

450

Reference CaseCμ = 0Cμ = 0.025Cμ = 0.05Cμ = 0.1

MERGER DELAYED

No Nozzle StructureUj/U∞ = 0Uj/U∞ = 2.0Uj/U∞ = 2.8 Uj/U∞ = 4.0

Vort

ex S

epar

atio

n / h

v

Increasing Jet FluxIncreases Vortex

Spacing

Rotation Angle

Effect of Jet Flux – Jet Inboard of Flap

Downstream development of vortex pair

Vortex Separation Distance

Vorte

x Sep

arat

ion

θ

ΓFlap

ΓTip

Increasing Jet FluxReduces Rotation Angle

ΓFlap/ Γ Tip = 1.0

0.75c0.6c

ΓFlap ΓTip

Page 16: Effect of an axial jet on aircraft wake vorticesfar-wake.irphe.univ-mrs.fr/IMG/workshop/PDF/FWW_24_Gursul.pdf · Effect of an axial jet on aircraft wake vortices D. Marles, P. Margaris,

y/c

z/c

-1.6 -1.4 -1.2 -1 -0.8 -0.6 -0.4 -0.2 0 0.2 0.4 0.6 0.8 1-1

-0.8

-0.6

-0.4

-0.2

0

0.2

0.4

0.6

0.8

1

1.2

1.4

24

20

16

12

8

4

0

y/c

z/c

-1.6 -1.4 -1.2 -1 -0.8 -0.6 -0.4 -0.2 0 0.2 0.4 0.6 0.8 1-1

-0.8

-0.6

-0.4

-0.2

0

0.2

0.4

0.6

0.8

1

1.2

1.4

(%)∞U

U std

x/c = 4, Uj/U∞ = 0 x/c = 4, Uj/U∞ = 2.8

Turbulence plot overlaid with streamlinesin rotating reference frame

ΓFlap/ Γ Tip = 1.0

0.75c0.6c

ΓFlap ΓTip

Effect of Jet Flux – Jet Inboard of Flap

Page 17: Effect of an axial jet on aircraft wake vorticesfar-wake.irphe.univ-mrs.fr/IMG/workshop/PDF/FWW_24_Gursul.pdf · Effect of an axial jet on aircraft wake vortices D. Marles, P. Margaris,

x/c

θ

0 5 10 15 20 250

50

100

150

200

250

300

350

400

450

Reference CaseCμ = 0Cμ = 0.025Cμ = 0.05Cμ = 0.1

x/c

h/h

v

0 5 10 15 20 250

0.2

0.4

0.6

0.8

1

1.2Reference CaseCμ = 0Cμ = 0.025Cμ = 0.05Cμ = 0.1

Vort

ex S

epar

atio

n / h

v

Increasing Jet FluxReduces Vortex Spacing

MERGER PROMOTED

No Nozzle StructureUj/U∞ = 0Uj/U∞ = 2.0Uj/U∞ = 2.8 Uj/U∞ = 4.0

Increasing Jet FluxIncreases Rotation

Angle

Vorte

x Sep

arat

ion

θ

ΓFlap

ΓTipDownstream development of vortex pair

Effect of Jet Flux – Jet Vertically Below FlapΓFlap/ Γ Tip = 1.0

Rotation Angle Vortex Separation Distance

0.75c

0.6c ΓFlap ΓTip

Page 18: Effect of an axial jet on aircraft wake vorticesfar-wake.irphe.univ-mrs.fr/IMG/workshop/PDF/FWW_24_Gursul.pdf · Effect of an axial jet on aircraft wake vortices D. Marles, P. Margaris,

y/c

z/c

-1.6 -1.4 -1.2 -1 -0.8 -0.6 -0.4 -0.2 0 0.2 0.4 0.6 0.8 1-1

-0.8

-0.6

-0.4

-0.2

0

0.2

0.4

0.6

0.8

1

1.2

1.4

24

20

16

12

8

4

0

(%)∞U

U std

y/c

z/c

-1.6 -1.4 -1.2 -1 -0.8 -0.6 -0.4 -0.2 0 0.2 0.4 0.6 0.8 1-1

-0.8

-0.6

-0.4

-0.2

0

0.2

0.4

0.6

0.8

1

1.2

1.4x/c = 4, Uj/U∞ = 0 x/c = 4, Uj/U∞ = 2.8

Turbulence plot overlaid with streamlinesin rotating reference frame

ΓFlap/ Γ Tip = 1.0

0.75c

0.6c ΓFlap ΓTip

Effect of Jet Flux – Jet Vertically Below Flap

Streamlines in a rotating reference frame superimposed with jet turbulence explain the importance of the initial jet configuration.

Page 19: Effect of an axial jet on aircraft wake vorticesfar-wake.irphe.univ-mrs.fr/IMG/workshop/PDF/FWW_24_Gursul.pdf · Effect of an axial jet on aircraft wake vortices D. Marles, P. Margaris,

ΓFlap ΓTip

I

ΓFlap ΓTip

III

ΓFlap ΓTip

II

T

x/c = 4

F

a)

x/c = 4

T

F

b)

x/c = 4c)

Turbulence gets trapped in the outer recirculation region

Page 20: Effect of an axial jet on aircraft wake vorticesfar-wake.irphe.univ-mrs.fr/IMG/workshop/PDF/FWW_24_Gursul.pdf · Effect of an axial jet on aircraft wake vortices D. Marles, P. Margaris,

Uj/U∞

h/h v

0 1 2 3 40

0.2

0.4

0.6

0.8

1

1.2

ΓFlap/ Γ Tip = 1.0hv/c = 1.0 Effect of Jet Flux and Configuration

ΓFlap ΓTip

ΓFlap ΓTip

Jet inboard of Flap

Jet vertically below centre of flap and tip

ΓFlap ΓTip

Jet vertically below flap

Vort

ex S

epar

atio

n / I

nitia

l vor

tex

Spac

ing

Vortex spacing at x/c = 20 as a function of jet exit velocity

Page 21: Effect of an axial jet on aircraft wake vorticesfar-wake.irphe.univ-mrs.fr/IMG/workshop/PDF/FWW_24_Gursul.pdf · Effect of an axial jet on aircraft wake vortices D. Marles, P. Margaris,

Summary

• Depending on the initial position of the jet, vortex merging can either be delayed or promoted:

→Jet Inboard of Flap (Merging Delayed) - jet turbulence trails the flap vortex as the vortices rotate. It alters the streamline pattern in the outer-recirculation region and inhibits the convective merger stage.

→Jet Vertically Below Flap (Merging Promoted) – Jet turbulence rapidly interacts with the flap vortex, causing it to diffuse which aids merging.

→ Streamlines in a rotating reference frame superimposed with jetturbulence explain the effect of the initial jet configuration.

• Different circulation ratios (ΓTip/ΓFlap = 0.65, 1.0, 1.54) and initial vortex spacings (hv/c = 0.75, 1.0) produced similar trends.

Vortex pair / jet interaction

Page 22: Effect of an axial jet on aircraft wake vorticesfar-wake.irphe.univ-mrs.fr/IMG/workshop/PDF/FWW_24_Gursul.pdf · Effect of an axial jet on aircraft wake vortices D. Marles, P. Margaris,

Γ2Γ1Small amplitudes (RMS less than 7%)

Pulsed jets

Simulation of pulsed engine jets

j

jj U

fdSt = Range of optimum frequencies for jets with external flow

(Michalke and Hermann)

• little effect

• additional turbulence generated close to the jet exit decays by the time it interacts with the wake vortices.

y/c

z/c

-1.4 -1.2 -1 -0.8 -0.6 -0.4 -0.2 0 0.2 0.4 0.6 0.8-1

-0.8

-0.6

-0.4

-0.2

0

0.2

0.4

0.6

0.8

1

1.2

y/c

z/c

-1.4 -1.2 -1 -0.8 -0.6 -0.4 -0.2 0 0.2 0.4 0.6 0.8-1

-0.8

-0.6

-0.4

-0.2

0

0.2

0.4

0.6

0.8

1

1.2

Page 23: Effect of an axial jet on aircraft wake vorticesfar-wake.irphe.univ-mrs.fr/IMG/workshop/PDF/FWW_24_Gursul.pdf · Effect of an axial jet on aircraft wake vortices D. Marles, P. Margaris,

Cycles

Uj/U

0 1 2 3 4 5 6 7 8 9 100

2

4

6

8

10

12

14

Jet v

eloc

ity hj

ps

hj/c

a/c

0 0.1 0.2 0.3 0.4 0.50

0.1

0.2

0.3

Reference CaseCμ = 0Cμ = 0.01, No PulsingCμ = 0.025, No PulsingCμ = 0.01, St c = 0.11Cμ = 0.025, St c = 0.11

Small flow control jets

Diffusion of the vortex was observed when the jet was located just outside the vortex core.

Dispersion buffer may damp any perturbations generated within the core.

Page 24: Effect of an axial jet on aircraft wake vorticesfar-wake.irphe.univ-mrs.fr/IMG/workshop/PDF/FWW_24_Gursul.pdf · Effect of an axial jet on aircraft wake vortices D. Marles, P. Margaris,

Conclusions

• Jet turbulence can wrap around the vortex or get ingested into the vortex

• Turbulence ingestion leads to decreasing cross-flow velocities (both in time-averaged and instantaneous sense)

• Important for flap-edge vortices

• Vortex merging can either be delayed or promoted, depending on the jet initial location

• Streamlines in a rotating reference frame superimposed with jet turbulence explain the effect of the initial jet configuration.

• Different circulation ratios and initial vortex spacings produced similar trends.

• Pulsed jets (with small amplitude) have little effect

• Small flow control jets may be useful as an active flow control method