Wake vortex characterization by Lidar Lidar technics ...wakenet.eu/fileadmin/wakenet2-europe/Wakenet2/Past Events/WG7, … · -2003 : development of a new mini-lidar set-up with triangulation

Office National d’Études et de Recherches Aérospatiales

www.onera.fr

Wake vortex characterization byLidar technics : catapult and field trials.

Wake vortex characterization byWake vortex characterization byLidar Lidar technicstechnics : catapult and field trials. : catapult and field trials.

J-P. J-P. CariouCariou,, A. A. DolfiDolfi,,D. D. GoularGoular, D. , D. FleuryFleury, B , B AugereAugere, M. , M. JallotJallot, JP , JP LafforgueLafforgue

ONERA, ONERA, PalaiseauPalaiseau, France, France..11/02/05

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Working plan during Joint ProjectWorking plan during Joint Project

MINI LIDARS for wake vortexmeasurements in catapultfacilities B10 and B20

LIDAR for full scale wake vortexmeasurement

SIMULATION software of lidarDoppler signature in a wind fieldrepresentative of a vortex pair

LIDABEMO

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DOTA DepartmentDOTA Department

DOTA : Applied and Theoretical Optics Department120 employees, 90 scientistslocated at Palaiseau, Châtillon, Toulouse and Salon

SLS : Laser Sources and Lidars Research Unit (15p)coherent lidars for remote sensingfibre sources for aerospace applications

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Working plan during PRFWorking plan during PRF

CATAPULT MEASUREMENTS

-1997-98 : development and improvements of SYLVA CO2 cw miniLIDAR for vortex measurement in catapult facility B10

-1999 : new measurement campaign & comparison between lidar andPIV measurements at catapult facility

-2003 : development of a new mini-lidar set-up with triangulationconfiguration for autonomous measurements in the B20 catapultfacility.

- 2004 : test of a new mini lidar technology, with an all fibre lidararchitecture at 1.5 µm .

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Working plan during PRFWorking plan during PRF

FIELD TEST MEASUREMENTS

- 2000 : development of DASH2 CO2 LIDAR for field test measurement.Measurement campaign in La Cépière TOULOUSE

- 2001 : improvement of DASH2 Lidar

SIMULATION SOFTWARE

- 2002 : development of the SLAVA software architecture

- 2003 : exploitation of the software

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Principle of coherent lidar measurementPrinciple of coherent lidar measurement

Laser anemometer :

A cw single frequency laser source (ν) is focused in the wind fieldAerosols, present in the vortex flow, backscatter part of incidentradiation, with a frequency shift fD corresponding to Doppler effect(fD= 2 Vr /λ) (Vr line-of-sight velocity)this Doppler shift fD is measured with coherent detection

LASER

°

°

°

V

Vr

Localoscillator

Mixer

Detector

Signalprocessing

ν

ν

ν

ν+fd

fd

v

-15

-10

-5

0

5

10

15

-40 -20 0 20 40

r(m)v(

m/s

)

22max.2)(

c

c

rrrVrrV

+=

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OUTLINEOUTLINE

CATAPULT MEASUREMENTS

FIELD TEST MEASUREMENTS

SIMULATION SOFTWARE

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MINI LIDAR CATAPULT MEASUREMENTSMINI LIDAR CATAPULT MEASUREMENTS

Lidarsystem

A 300model

lidar beam scanningseeding with smokeor oil droplets

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Lidar experimental set up at the B10

θ = 40°

Scanning mirror

2 m

3,7m

CO2 Lidar

mirrormirror

alignement laser

MCT detector

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5Lidar characteristics for catapult

measurements

aircraft :• 1/20 th scale (span = 2 m)• speed 23 m/s• distance between model departure plan and laser plan (lidar+PIV) : 8 m• distance between model departure plan and arrival plan: 22 m

lidar :• wavelength : 10.6 µm• laser Power : 3 W• Doppler sensitivity: 189 kHz/m.s-1

• speed range : 0 - 10 m/s• angular resolution : 0.05°• speed resolution : 0.05 m/s• pupil diameter : 15 mm• focus distance : 5 m• measurement volume length : 4.5 m• measurement volume diameter : 2.6 m

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5First measurement results in homodyne

configuration

0

5

1 0

1 5

2 0

2 5

3 0

3 5

4 0

4 5

5 0

a n g le °

Vite

sses

en

m/s

V it e s s e V o r t e x ( s p e c t re lo g )

1 0 1 5 2 0 2 5 3 0 3 5 4 0 4 50

1

2

3

4

5

6

7

8

9

1 0

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5Lidar/PIV comparison :PIV vector projection on lidar axis

0.5

1

1.5

2

2.5

3

3.5

4

4.5

5

5.5PIV21

850 900 950 1000 1050 1100

2900

2950

3000

3050

3100

PIV21

850 900 950 1000 1050 1100

2900

2950

3000

3050

3100

PIV vectors + Lidar axis Intensity of PIV vector projection on lidar axis

m/s

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Comparaison Lidar/PIV

-8

-6

-4

-2

0

2

4

6

8

10

12

angle °

Vite

sses

en

m/s

Vortex lidar:ts t11510e - piv:env=21

28 29 30 31 320

1

2

3

4

5

6

7

8

9

10

0

5

10

15

20

25

30

35

40

angle °

vite

sses

en

m/s

ts t1510e-datel5

28 28.5 29 29.5 30 30.5 31 31.5 320

1

2

3

4

5

6

7

8

9

10

PIV data Lidar data

dB

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5SYLVA MINI Lidar improvement

Heterodyne detection implementationSYLVA MINI Lidar improvement

Heterodyne detection implementation

LASER

telescope

mixerLocal oscillator

ν

νν + FD

FD +νol

ZV

Vr

ν+ νol

Detection

Signalprocessing

ννν

•wavelength : 10.6 µm•laser power : 3 W•pupil diameter : 15 mm•measurement volume length : 4,5 mat 5 m•measurement volume diameter : 3mm•scanning time : 0.4 s (4 wingspans)

Doppler sensitivity: 189 kHz/m.s-1

speed range : -10 +10 m/sangular resolution : 0.05°speed resolution : 0.05 m/s

AOM

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New optical Optical lidar layoutNew optical Optical lidar layout

CO 2 LASER

M2

M3

Lc

M1

Ld

LS1

LS2

Pg

AOMScanningmirror

λ/2

λ/4

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Measurement exemple (A300)Measurement exemple (A300)

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5Example of lidar measurement :

velocity spectra as a function of wing spans

Spee

d m

/s

Wing spans & (scanning angle)

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Angular position of core centre and diameterAngular position of core centre and diameter

0

5

10

15

20

25

30

35

40

0 5 10 15 20 25 30 35

wing spans

angl

e (°

)flight 106 m106 m

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Cores trajectories : repeatabilityCores trajectories : repeatability

time in seconds

Ang

le °

Repeatability : 4 successive flights, same model, same configuration

0

5

10

15

20

25

30

35

40

0 0.5 1 1,5 2 2,5 3 3,5 4 4,5

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Comparison of TOMOSCOPY & LIDAR data Comparison of TOMOSCOPY & LIDAR data

Angle °

Wing spans0 10 20 30 40 50 60

10

15

20

25

30

35

40F 13

Tomoscopy cores angular positions

Lidar cores angular positions

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Circulation calculation

• Circulation : good parameter to estimate thevortex strength and effects on potential wakeencounters

•Γ= 2.π.r.V(r) for 2.rc < r < rmaxr is the distance from the core centre2rc : core diameter

• Absolute core position given by Tomoscopy

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Circulation calculationCirculation calculation

3.5 4 4.5 5 5.5 6 6.5 70

wingspans

circ

ulat

ion

Wake vortex profile

right core position

left core position

scanning angle

vortex radius

circulation

Circulation 2rc:2

0,00

0,50

1,00

1,50

2,00

2,50

3,00

3,50

4,00

4,50

5,00

0,00 5,00 10,00 15,00 20,00 25,00 30,00 35,00

wing span

circ

ulat

ion

(m2/

s)

A300

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Circulation calculation

In B10 , lidar is side viewingPart between the cores are

mixed.

For circulation, only outerparts of the vortex are used

circulation values arebiased by superposition ofthe two vortices

In B10, altitude of flight is too low to see vortex decay

in circulation values

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New B20 facility ( 90 m x 20 m x 20 m) is operational since 2002

The lidar is set under the model trajectory good separation

between vortices accurate circulation estimation.

Catapult measurements : New B20 facility

Lidar

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B20 and B10 lidar measurements comparisonB20 and B10 lidar measurements comparison

Wing spans

Spee

d m

/s

*10

*10

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Lidar CO2Continuous Wave

Velocity resolution5cm/s

Cores localisation :10 cm

Measurements upto 100 spans

The CO2 mini-Lidar comprises two scanning mirrors for measuringvortex cores trajectories, velocity profiles and vortex circulation behinda catapulted model.

M1

B20 mini-lidar set-upwith triangulation configuration

Mobile along the track

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B20 catapult facility at LilleB20 catapult facility at Lille

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Mini lidar installation at the B20 facilityMini lidar installation at the B20 facility

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B20 mini-lidar configurationB20 mini-lidar configuration

Focus =8m

Relative sensitivity of detection (dB) for the 2 points of view

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5Example of time evolution of a vortex pair velocity spectra

measured by the mini-LIDAR (viewed from M1)

Vel

ocity

(m/s

)

span

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-0.5 -0.4 -0.3 -0.2 -0.1 0 0.1 0.2 0.3 0.4 0.5-6

-4

-2

0

2

4

6

r/span

v m

/s

flight n°21. spe e d evolution in left vortex

t/t0=0.354 span=13.861t/t0=0.578 span=22.617t/t0=0.801 span=31.328t/t0=1.023 span=40.048t/t0=1.247 span=48.795t/t0=1.472 span=57.604t/t0=1.697 span=66.405t/t0=1.924 span=75.286t/t0=2.151 span=84.149

Wake Vortex Characterisation By Lidar Triangulation inB20 facility within AWIATOR Project : example of results

Temps en s

Vitesse en m/s

0 2 4 6 8 10 12 14 16

-4

-3

-2

-1

0

1

2

3

4

0 0.5 1 1.5 2 2.5 3 3.5 40

0.5

1

1.5flight n°27....c irculation integra ted be tween b/12 & b/4

t/t0

gam

a/ga

m0

a ve rage of right and le ft vortex c ircula tionright core c ircula tionleft core c ircula tion

-2000 -1500 -1000 -500 0 500 1000 1500 20003000

3500

4000

4500

5000

5500

6000

6500

7000

7500

8000

Y(mm)

Z (m

m)

flight n°22....tria ngulation tra jec tory

right vortexle ft vortex

18 s long lidar measurement

Vortex cores trajectories Velocity profile Circulation

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5Test of a new mini lidar technology, with an allfibre lidar architecture at 1.5 µmTest of a new mini lidar technology, with an allfibre lidar architecture at 1.5 µm

Ps [email protected] µm

POL

Ps

ObjectiveTilted face

DetectionG

CirculatorT

R

Det

Lidar volume and weight divided by 10Doppler sensitivity multiplied by 7

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image globale -23112004-141501102416-vol0-global.mat

temps en s econdes (16 moyennages )

vite

sses

en

m/s

4.1 4.2 4.3 4.4 4.5 4.6

0.5

1

1.5

2

2.5

3

3.5

4

4.5

5

10

15

20

test of a new mini lidar technology, with an allfiber lidar architecture at 1.5 µmtest of a new mini lidar technology, with an allfiber lidar architecture at 1.5 µm

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OUTLINEOUTLINE

CATAPULT MEASUREMENTS

FIELD TEST MEASUREMENTS

SIMULATION SOFTWARE

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5FIELD TEST MEASUREMENTSFIELD TEST MEASUREMENTS

Dash2 : CO2 CW coherent lidar

Bemol : truck platform

Topac : optronic pointing / scanning / tracking system

Gargantua : ADC and data storage

Weather station

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Dash 2 LIDARDash 2 LIDAR10.6 µm ,coherent CW lidar

30 cm aperture

focus distance : from 50 m up to ∞longitudinal size of the probe volume :12 m at 200 m

velocity range : ± 37 m/s

velocity resolution : 10 cm/s(with 100 spectra averaged)

angular resolution : 0.17 °

real time display with a SAW spectrumanalyser

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5 LIDAR

BEMOL

BemolBemol

stabiliser

Crane +Power generator

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02/05/01 F0 n°5

time in second s

radi

al v

eloc

ity m

/s2.6404 2.6405 2.6405 2.6406 2.6406 2.6406 2.6407 2.6408

x 104

-10

-8

-6

-4

-2

0

2

4

6

8

10

Before After

LIDAR DASH II improvement (2000 2001)LIDAR DASH II improvement (2000 2001)

No speed signPoor contrast

Speed signGood contrast

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0

5

10

15

20

25

30

35-26/04/2001- FO n°10

Time in s

Rad

ial v

loci

ty m

/s

3.5727 3.5728 3.5728 3.5728 3.5729 3.573 3.573x 104

-25

-20

-15

-10

-5

0

5

10

Mesurable speed > 25 m/s in the early (wrap-up) period ( scan speed = 20 °/s)

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60

80

100

120

140

160

180

200

220

240

Temps en s

Vite

sse

en m

/s

Run0x05.vor

0 10 20 30 40 50 60

-15

-10

-5

0

5

10

15

0

50

100

150

200

250

300

350

Temps en s

Vite

sse

en m

/s

Run0x05.vor-ima5

12 12.5 13 13.5 14 14.5 15 15.5 16

-15

-10

-5

0

5

10

15 Close-up of two pairs

Over 30 intersections of lidar beamwith vortex pair

(ONERA data from C-Wake trial)

Time0 60s

0

+15m/s

-15

Fast scan: multiple intersections with vortices

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5TRIANGULATION CONFIGURATION with QinetiQ LIDAR

during WAKEOP campaign at Munich April 2001

0

40

80

120

160

200

240

120

TOPAC

LIDAR

BEMOL

Onera QinetiQ

LIDAR

wind

triangulation zone

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5Vortex trajectory computation by

triangulationVortex trajectory computation by

triangulation

-20 -10 0 10 20 30 4095

100

105

110

115

120

125

130

135triangulation Qinetiq-ONERA du : Vol 5 02/05/2001

X (m)

Z (m

)

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Strategy of lidar measurements at Tarbes airfield

Onera lidar DLR lidar

Onera lidar DLR lidar

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B20B20

-1 -0.8 -0.6 -0.4 -0.2 0 0.2 0.4 0.6 0.8 1-0.2

-0.15

-0.1

-0.05

0

0.05

0.1

0.15

0.2

r/(s pan/2)

V/V

0

flight n°10. s peed evolution in le ft vortex

t/t0=0.32 s pan=013.5t/t0=0.53 s pan=022.2t/t0=0.74 s pan=031.0t/t0=0.95 s pan=039.7t/t0=1.16 s pan=048.5t/t0=1.37 s pan=057.2t/t0=1.58 s pan=065.9t/t0=1.79 s pan=074.7t/t0=2.00 s pan=083.4t/t0=2.21 s pan=092.2

TarbesTarbes

-1 -0.8 -0.6 -0.4 -0.2 0 0.2 0.4 0.6 0.8 1-0.2

-0.15

-0.1

-0.05

0

0.05

0.1

0.15

0.2

r/(s pan/2)

V/V

0 m

/s

flight n°:1-13. s peed evolution in le ft vortext/t0=0.47 s pan=017.8t/t0=0.61 s pan=023.4t/t0=0.76 s pan=029.0t/t0=0.91 s pan=034.7t/t0=0.91 s pan=034.7t/t0=1.06 s pan=040.3t/t0=1.21 s pan=045.9t/t0=1.35 s pan=051.5t/t0=1.50 s pan=057.1t/t0=1.65 s pan=062.7t/t0=1.80 s pan=068.3t/t0=1.94 s pan=074.0

Comparison betweeen B20 and fieldmeasurements

Comparison betweeen B20 and fieldmeasurements

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OUTLINEOUTLINE

CATAPULT MEASUREMENTS

FIELD TEST MEASUREMENTS

SIMULATION SOFTWARE

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Organisation chart of SLAVALidar inputs Atmospheric

inputsVortex inputs

Backscatteringcoefficient in the lidaranalysis plan

radial velocity alongthe line of sight

Wind field in the lidaranalysis plan

Theoreticalvelocity

profile V(r)

Velocity histogram

Temporal heterodynesignal

Spectral processing

Doppler image of thewind field function ofthe scanning angle.

Vmaxpoints

positionsTheoreticalcirculation

Lidar sensitivityalong the line ofsight

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Atmospheric inputs

Aerosol profile Wind profile

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Vortex inputs : theoretical model

Comparison of ideal modelswith experimentalmeasurements made in 2002on wakes of a A340 Airbus.

Hallock-Burnham : Γ0= 436 m/s², rc=3.3m

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Vortex inputs : vortex wind field

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Lidar inputs : heterodyne detection sensitivity

Measurement volume

Axial sensitivity

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Lidar inputs : scanning pattern

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5 0 0.1 0.2 0.3 0.4 0.5 0.6 0.7 0.8 0.9 1

x 10-4

-100

-50

0

50

100

signal temporel codé 8 bits

4 4.2 4.4 4.6 4.8 5 5.2 5.4 5.6 5.8 6

x 106

0

10

20

30

40

50

60

70spectres moyennés sur Ns - échelle en dB

Heterodyne signal time serie

Spectral processing

Doppler image ofthe wind field vsscanning angle.

Outputs

TF

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Intermediate outputs : theoretical circulation

Theoretical circulation(b/12-b/4) of an Hallock-Burnham ( Γ0= 436 m2/s,rc=3.3m ):0.93*Γ0.

-0.2 -0.1 0 0.1 0.2 0.30.8

0.85

0.9

0.95

1

1.05

1.1

%

circulation as a function of core position error vortex type : Hallock-Burman : Γ0=436 m2/s ; rcore=3.3 m

circulation / theoretical circulation circulation / circulation with no core position errorVortex profil (arbitrary unit )

core position error / span

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5 Intermediate outputs : Vmax points positions

function of angle of view

mean angle of view = 90°(lidar under the vortex)

mean angle ofview = 45°

mean angle ofview = 43°

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5 Intermediate outputs :circulation vs angle of view

example of velocity spectrafor vortices at 200 m, mean angle of view= 45 °, a focusing lidar to 282 m and a signal tonoise ratio on of -5 dB

circulation functionof angle of view

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Output : velocity profiles function of SNR

S/B=10 dB

Examples : vortex altitude= 200 m , Focus distance = 200 m , angle of view =90°Profile extraction level = 2 dB above the noise level.

S/B=0 dB

S/B= -10 dB S/B= -15 dB

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Measurement strategy for unseeded vortexMeasurement strategy for unseeded vortex

-Measurement of signal to noise ratio on wind on a spectrumanalyser ( narrow bandwidth)

- Extrapolation of signal to noise ratio to the vortex analyserbandwidth.

- -

circulation as a function of SNR and focalisation

-20

-15

-10

-5

0

5

10

15

20

25

0 100 200 300 400 500 600

focalisation distance

SNR

(dB

)

ninimum signal to noise ratio for a good circualtionevaluation (circulation value between 0.9 et 1)maximum signal to noise ratio for a good circualtionevaluation (circulation value between 0.9 et 1)

vortex at 100 m

vortex at200 m

vortex at400 m

possible altitude for aircraft

tolerable defocusing

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Simulation

Atmospheric parameters : -horizontal wind speed :-5 m/s - vertical wind speed :0m/s - wind shear :

height : 100 m thickness: 5m speed gradient : 2.5 m/s

Vortex parameters :-altitude : 200 m

Lidar parameters :-mean angle of view = 74 °-focus distance = 150 m

Interpretation of real signals Interpretation of real signals

Tarbes 02 measurementSimulated velocity spectrum Experimental velocity spectrum

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Summary of lidar modelingSummary of lidar modeling

≡ SLAVA : simulation software of lidar Doppler signaturein a wind field representative of a vortex pair

≡ Main Applications for cw heterodyne lidar :- error on measured parameters estimation (core diameter,

velocity profile, circulation)- lidar measurement domain for vortex detection

≡ signal interpretation help≡ signal processing optimisation

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ConclusionsConclusions

≡ Since 1997, DST Joint Program has been an efficientsupport to :

∨ to develop first lidars at Onera for vortex monitoring∨ to improve the tools for participating to international

campaigns (C-Wake, AWIATOR)∨ to test new generation lidars at the B20 facility∨ to develop modeling tools∨ To participate to a common effort at Onera in the field of

Wake Vortex understanding.Harris, M., Young, R. I., Köpp, F., Dolfi, A., and Cariou, J.-P.Aerospace Science and Technology, Vol. 6, 2002, pp. 325-331Wake Vortex Detection and MonitoringKöpp, F., Smalikho, I., Rahm, S., Dolfi, A., Cariou, J.-P., Harris, M., Young, R. I., Weekes, K., and Gordon, N.AIAA Journal, Vol. 41, 2003, pp. 1081-1088.Characterisation of Aircraft Wake Vortices by Multiple-Lidar TriangulationHolzäpfel, F., Gerz, T., Köpp, F., Stumpf, E., Harris, M., Young, R. I., and Dolfi, A.Journal of Atmospheric and Oceanic Technology, Vol. 20, 2003, pp. 1183-1195.Strategies for Circulation Evaluation of Aircraft Wake Vortices Measured by Lidar