ExperimentalApparatus

„L-6” Twin-Jet Shear LayerWind Tunnel1

2

3

4

5

8

6

7

9

10

7

11

1 L-6 Wind Tunnel2 Smoke Generators3 Smoke Suction Unit4 Wing Profiles for Smoke Injection5 Power Supply for the Spray6 Spray Nozzle7 Honeycombs8 Water Tank9 Blowers

10 Screens + Foam Sheets11 Test Section

U1

High Velocity StreamU2

Low Velocity Stream

xy

z000

100

200

300

400

500

-150 -100 -50 0 50 100 150

85

50

Area of PIV Image

Recordings

85

50

Skipped PIV Positions

100

1003

550

Splitter Plate/SP/

Test SectionTest Section

VON KÁRMÁN INSTITUTE FOR FLUID DYNAMICSNr3)

Measurement TechniquesMeasurement Techniques

PIV /for single-phase flow/new PCO camera + NIKKOR 35mmnew PCO camera + NIKKOR 35mm

Image size: 1280Image size: 1280××768 pixel (768 pixel (≈≈ 8585××50 mm)50 mm)Nd:YAGNd:YAG pulsed laser /6W/pulsed laser /6W/Positioning systemPositioning systemSensiCamSensiCam acquisition softwareacquisition software

PTV(S) /for two-phase flow/Particle Tracking Velocimetry and Sizing

Size Discriminating (Size Discriminating (ddseedingseeding «« dddropletdroplet))Gas Phase Flow Field Data in TwoGas Phase Flow Field Data in Two--Phase FlowPhase Flow

PostPost--processingprocessing::MatlabMatlab, , TecPlotTecPlot, Excel, Excel

VON KÁRMÁN INSTITUTE FOR FLUID DYNAMICS

PARTICLE IMAGINGPARTICLE IMAGINGVELOCIMETRYVELOCIMETRY

lasersheet

Nd:YAGpulsedlaser

Oil smokeseeding particles

Spray NozzleDroplet Injection

outer inner outer

U1 U2

SensiCam

Nr3)

FlowVisualization

U1 = 2 m/sU2 = 1 m/s

FlowVisualization

U1 = 2 m/sU2 = 1 m/s

U1 U2 U1 U2

well definedmixing layer

developement

000

100

200

300

500

Two-phase flowSingle-phase flow

DigitalImage

Recordingfor

ParticleImaging

Velocimetry

PIV PTV(S)

400

VON KÁRMÁN INSTITUTE FOR FLUID DYNAMICSNr3)

Two-phase flowSingle-phase flow

>

000

100

200

U1 U2 U1 U2Flow

Visualization

U1 = 2 m/sU2 = 1 m/s

FlowVisualization

U1 = 2 m/sU2 = 1 m/s

shear layerflow structure/droplets in themixing layer/

VON KÁRMÁN INSTITUTE FOR FLUID DYNAMICSNr3)

ExperimentalResults

Digitally recordedsuccessive

images

∆ta-b

ExperimentalResults

Digitally recordedsuccessive

images

∆ta-b

a

b

VON KÁRMÁN INSTITUTE FOR FLUID DYNAMICS

Nr3)

ExperimentalResults

single-phase flowPIV

/comparison of PIV-PTV(S)/

two-phase flowPTV(S)

Velocity Profiles of Gas Phase in Single-Phase Flow/ U1=2m/s, U2=1m/s, r=0.5, λ=0.33 /

0

0.5

1

1.5

2

2.5

3

-35 -30 -25 -20 -15 -10 -5 0 5 10 15 20 25 30 35 40 45 50

Distance from Splitter Plate, y [mm]

Velo

city

Mag

nitu

de, U

g [m

/s]

10mm PIV

300mm PIV

10mm PTVS

300mm PTVS

Streamwise direction, x

Velocity Profiles of Gas Phase in Single-Phase and Two-Phase Flow/ U1=2m/s, U2=1m/s, r=0.5, λ=0.33 /

0

0.5

1

1.5

2

2.5

3

-35 -30 -25 -20 -15 -10 -5 0 5 10 15 20 25 30 35 40 45 50

Distance from Splitter Plate, y [mm]

Velo

city

Mag

nitu

de, U

g [m

/s]

10mm PIV single-phase flow

300mm PIV single-phase flow

10 mm PTVS two-phase flow

300mm PTVS two-phase flow

Streamwise direction, x

VON KÁRMÁN INSTITUTE FOR FLUID DYNAMICS

Nr3)

Two-phase flow characteristics IntroductionTwo-phase flow characteristics Introduction

[[ELGHOBASHI,ELGHOBASHI, 19941994]] [[GOGORE and CROWERE and CROWE,, 19198899]]

αp = 10-4 ÷ 10-5 Stp = 10-3 ÷ 102 ∆(T.I.) = f (dp/le)

VON KÁRMÁN INSTITUTE FOR FLUID DYNAMICSNr3)

Environmental and Applied Fluid Dynamics DepartmentFinal Public Presentation on 26th/06/2000

Turbulence Modulation Map

Environmental and Applied Fluid Dynamics DepartmentFinal Public Presentation on 26th/06/2000

Turbulence Modulation Map

Effect of Effect of characteristic length characteristic length scale ratioscale ratio on modulating on modulating turbulent intensity:turbulent intensity:

∆∆(T.I.) = (T.I.) = ff ((ddpp/l/lee))

ddpp -- particle diameterparticle diameterllee -- fluid length scalefluid length scale (integral (integral length scale or characteristic length of length scale or characteristic length of the most the most energetic eddy)energetic eddy)

T.I. of the fluid based on PIV and PTVS velocity meas.T.I. of the fluid based on PIV and PTVS velocity meas.

graph from [Gore and Crowe, 1989]graph from [Gore and Crowe, 1989]in Int. J. Multiphase Flowin Int. J. Multiphase Flow Vol.Vol.1515. No.2, pp.279. No.2, pp.279--285.285.

VON KÁRMÁN INSTITUTE FOR FLUID DYNAMICS

( )phasesingle

phasesinglephasetwophasecarrier ..

......

−

−− −=∆

ITITIT

IT

exp. results: Suda 2000.

Mixing Layer: negative rel. change (- 90%)Main Flow: positive rel. change (+1500%)

Nr3)

CHANGE in Turbulence Intensity CONCLUSIONSCHANGE in Turbulence Intensity CONCLUSIONS

Effect of Effect of characteristic length characteristic length scale ratioscale ratio on modulating on modulating turbulent intensity:turbulent intensity:

∆∆(T.I.) = (T.I.) = ff ((ddpp/l/lee))

ddpp -- particle diameterparticle diameterllee -- fluid length scalefluid length scale (integral (integral length scale or characteristic length of length scale or characteristic length of the most the most energetic eddy)energetic eddy)

T.I. of the fluid based on PIV and PTVS velocity meas.T.I. of the fluid based on PIV and PTVS velocity meas.

graph from [Gore and Crowe, 1989]graph from [Gore and Crowe, 1989]in Int. J. Multiphase Flowin Int. J. Multiphase Flow Vol.Vol.1515. No.2, pp.279. No.2, pp.279--285.285.

( )phasesingle

phasesinglephasetwophasecarrier ..

......

−

−− −=∆

ITITIT

IT

exp: [Suda, 2000]

Mixing Layer: negative rel. change (- 90%)Main Flow : positive rel. change (+1500%)

Cumulative PDF for x=300 mm

0

0.1

0.2

0.3

0.4

0.5

0.6

0.7

0.8

0.9

1

-100 -80 -60 -40 -20 0 20 40 60 80 100Distance from Splitter Plate, y [mm]

dp = 300 micron

dp = 150 micron

dp = 50 micron

33% of 33% of ddpp= 50= 50µµmm

14% of 14% of ddpp=300=300µµmm

VON KÁRMÁN INSTITUTE FOR FLUID DYNAMICS

Nr3)