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)