CVEN 679 Term Project Presentation Multiphase Flow studies using PIV Collaborators: CHAMPA JOSHI TIRTHARAJ BHAUMIK RAMAKRISHNAN HARI PRASAD.

CVEN 679 Term Project Presentation

Multiphase Flow studies using Multiphase Flow studies using PIVPIV

Collaborators:Collaborators:

CHAMPA JOSHICHAMPA JOSHI

TIRTHARAJ BHAUMIKTIRTHARAJ BHAUMIK

RAMAKRISHNAN HARI RAMAKRISHNAN HARI PRASADPRASAD

PROJECT OBJECTIVEPROJECT OBJECTIVE

The PIV (Particle Image Velocimetry) The PIV (Particle Image Velocimetry) measurement method is used to obtain relevant measurement method is used to obtain relevant parameters in the study of multiphase plumes parameters in the study of multiphase plumes with the objective of validating numerical models with the objective of validating numerical models and use them to predict field phenomena.and use them to predict field phenomena.

MULTIPHASE FLOW BASICSMULTIPHASE FLOW BASICS

Multiphase flows are fluid flows involving Multiphase flows are fluid flows involving the dynamics of more than one phase or the dynamics of more than one phase or constituentconstituent

One of the core areas of research inOne of the core areas of research in Environmental Fluid MechanicsEnvironmental Fluid Mechanics

Dispersed & Continuous PhasesDispersed & Continuous PhasesDispersed Phase : Bubbles, Droplets, PowderDispersed Phase : Bubbles, Droplets, Powder

Continuous Phase : Water, AirContinuous Phase : Water, Air Jets:Jets:

Driving force – Momentum flux of dispersed phaseDriving force – Momentum flux of dispersed phase Plumes:Plumes:

Driving force – Buoyancy flux of dispersed phase Driving force – Buoyancy flux of dispersed phase

ApplicationsApplications

Bubble BreakwatersBubble Breakwaters Antifreeze measures in HarborsAntifreeze measures in Harbors Bubble curtains for Oil spill Bubble curtains for Oil spill

containmentcontainment COCO22 Sequestration in Ocean Sequestration in Ocean Lake AerationLake Aeration Reservoir DestratificationReservoir Destratification

SCHEMATIC OF A SIMPLE AIR-BUBBLE PLUMESCHEMATIC OF A SIMPLE AIR-BUBBLE PLUME

BubblesBubbles (Dispersed Phase)

Water (Continuous phase)

MULTIPHASE PLUMES IN STRATIFIED MULTIPHASE PLUMES IN STRATIFIED ENVIRONMENTENVIRONMENT

LIF Image of a Type 3 plume

N=((-g/ρr)*(dρa/dz))1/2

hP

Dimensional Analysis:Dimensional Analysis:

hT = f (Qinit , Minit , Bb_init , Bw_init , us , N , HT )

0 0 0

Total no. of variables = 4Total no. of dimensions = 2 (L, T)

BUCKINGHAM-PI THEOREM

(4 – 2) = 2 non-dimensional groups

∏1 : Non-dimensional Trap Height

∏2 : Non-dimensional Bubble Slip Velocity

∏1 = hT / (B/N3)¼

∏2 = us / (BN)¼

∏1 = g ( ∏2 )

Single-phase plumes: ∏1 = 2.8

Two-phase plumes:

Relationship between the non-dimensional parameters validated from experiments:

∏1 = 2.8 – 0.27∏2 ∏1 = 5.2exp(-(П2 – 1.8)2/10.1)

Field Scale Complications:Field Scale Complications: Stratification profile may be non-linear Stratification profile may be non-linear

- N varies with depth- N varies with depth There may be bubble expansion There may be bubble expansion

- u- uss varies with depth varies with depth There may be more than one dispersed There may be more than one dispersed

phases presentphases present

LEADS TO:LEADS TO:

Poor correlation between lab and field scales!Poor correlation between lab and field scales!

REMEDY:REMEDY:Numerical models with parameters validated from laboratory Numerical models with parameters validated from laboratory

experiments can include the field-scale complicationsexperiments can include the field-scale complications

Governing Differential Equations:Governing Differential Equations:

Conservation of Mass fluxConservation of Mass flux Conservation of Momentum fluxConservation of Momentum flux Conservation of Buoyancy flux of dispersed phaseConservation of Buoyancy flux of dispersed phase Conservation of Buoyancy flux of continuous Conservation of Buoyancy flux of continuous

phasephase

Unknown parameters to be solved:Unknown parameters to be solved:

UUmm –– velocityvelocity of continuous phase of continuous phase 2b2b – – widthwidth of plume of plumeCCmm – – void fractionvoid fraction of dispersed phase of dispersed phaseg’g’ – – reduced gravityreduced gravity of continuous phase of continuous phase

Gaussian and Top-Hat profiles:Gaussian and Top-Hat profiles:

Top-Hat Distribution Gaussian Distribution

SELF – SIMILARITY ASSUMPTION

X(r,z) = X(z), -b r b

= 0 elsewhere

2

m 2 2

rX(r,z) = X (z)exp(- ), -b r b

b = 0 elsewhere

X: state variable of interest ( u, C, ∆ρ)

Derivation of the Governing Equations:Derivation of the Governing Equations:

Entrainment Hypothesis

Dilute plume assumption

Density locally invariant inside C.V

Balance of buoyant forces on two phases

Viscous Drag is negligible for water

Momentum of air bubbles is negligible

b b2

-b -b

b

-b

Q(z)= u(r,z)dA, M(z)= u (r,z)dA,

B(z) = g'(r,z) udA, dA = 2πrdr

2b

Numerical models:Numerical models:

Mixed-fluid model :Mixed-fluid model : McDougall (1978), McDougall (1978), Asaeda & Imberger Asaeda & Imberger

(1993)(1993)

- - Treats the dispersed and continuous phases as a single Treats the dispersed and continuous phases as a single mixturemixture

Two-fluid model : Two-fluid model : Socolofsky & Adams Socolofsky & Adams (2001)(2001)

- - Treats the dispersed and continuous phases as separate Treats the dispersed and continuous phases as separate entitiesentities

Numerical Model Equations:Numerical Model Equations:

NUMERICAL SCHEME USED: 4TH ORDER RUNGE-KUTTA

Critical Model Issues:Critical Model Issues:

Entrainment CoefficientEntrainment Coefficient

Initial conditionsInitial conditions

Um , b and alpha are to be estimated using PIV measurements

Particle Image VelocimetryParticle Image Velocimetry

Facilities & EquipmentsFacilities & Equipments

Experimental Tank Experimental Tank (40 x 40 x 70 cm)(40 x 40 x 70 cm) made of transparent acrylic glass (Plexiglas) made of transparent acrylic glass (Plexiglas) Diffuser source Diffuser source (Airstone - 1.4 cm dia) – produces bubbles of 3 mm dia above Q = (Airstone - 1.4 cm dia) – produces bubbles of 3 mm dia above Q =

0.25 l/min0.25 l/min Electronic Mass Flowmeter Electronic Mass Flowmeter (Aalborg GFM 171)(Aalborg GFM 171) and Needle valve and Needle valve 3.2 mm piping3.2 mm piping Laser Light Source: Laser Light Source: (Nd:YAG pulse laser)(Nd:YAG pulse laser)

-- Maximum powerMaximum power (400 mJ/pulse)(400 mJ/pulse)-- WavelengthWavelength (532 nm - green) (532 nm - green)-- Pulse widthPulse width ( 8 nanoseconds) ( 8 nanoseconds)-- Time interval between pulsesTime interval between pulses ( 4 ms ) ( 4 ms )-- Thickness of laser light sheetThickness of laser light sheet (4 mm) (4 mm)

OpticsOptics - Cylindrical Lens – creates planar light sheet - Cylindrical Lens – creates planar light sheet Seeding Particles Seeding Particles – Polyamide spheres (white, 50 – Polyamide spheres (white, 50 μμm diameter)m diameter) Camera (CCD) – Camera (CCD) – Flowmaster 3S (3)Flowmaster 3S (3)

-- Frame rateFrame rate (8 fps) (8 fps)-- PixelPixel ResolutionResolution (1280 x 1024) (1280 x 1024)-- Grayscale ResolutionGrayscale Resolution (12-bit : 0 to 4095 grayscales) (12-bit : 0 to 4095 grayscales)-- Field of ViewField of View (18cm x 18 cm for each of the 3 cameras) (18cm x 18 cm for each of the 3 cameras)-- Controllable exposure timeControllable exposure time (0.2 to 125 ms) (0.2 to 125 ms)

ComputerComputer-- Data analysis softwareData analysis software – DaVis (product of LaVision GmBH) – DaVis (product of LaVision GmBH)-- Synchronization unitSynchronization unit – controls timing of laser pulse triggering and camera – controls timing of laser pulse triggering and camera exposureexposure-- Frame Grabber Frame Grabber – captures frames and transfers to computer RAM and then – captures frames and transfers to computer RAM and then to Hard Diskto Hard Disk-- UtilitiesUtilities – Matlab – Matlab

PIV EPIV EXPERIMENTALXPERIMENTAL S SETUPETUP

MMEDIAN EDIAN FFILTERING FOR ILTERING FOR PIV PIV DATADATA

UMEDIAN – 1.5URMS < U < UMEDIAN + 1.5URMS

Interrogation Window – 16 X 16 pixels, 50% overlap

PTV APTV ANALYSIS BY NALYSIS BY TTHRESHOLDHRESHOLD

Original image

[mm]0 5 10 15 20 25 30 35 40 45 50

0

5

1015

20

2530

3540

45

50

Threshold applied image

[mm]0 5 10 15 20 25 30 35 40 45 50

0

510

15

2025

30

35

4045

50

Grayscale intensity Threshold Range for a 12-bit CCD camera: 0 – 4095

Intensity Threshold for the brighter bubbles: 2500

FFLUID & LUID & BBUBBLE UBBLE VVELOCITYELOCITY P PROFILESROFILES

Fluid velocity profile: Resembles Gaussian

Bubble velocity profile: Resembles Top-Hat

EENTRAINMENT NTRAINMENT CCOEFFICIENT FROM PIVOEFFICIENT FROM PIV

IMPORTANT FINDING: Alpha is not constant and varies non-linearly with depth

1( *) 0.055

2502( *)z

z

COMPARISON W/TWO-FLUID MODELCOMPARISON W/TWO-FLUID MODEL

0.05 0.1 0.15 0.2 0.25 0.3 0.35 0.40

0.01

0.02

0.03

0.04

0.05

z/H

T

Q/(Bz5)1/31.6 1.8 2 2.2 2.4 2.6 2.8 30

0.01

0.02

0.03

0.04

0.05

z/H

T

Um/(B/z)1/3

0.1 0.12 0.14 0.16 0.18 0.2 0.22 0.24 0.260

0.01

0.02

0.03

0.04

0.05

z/H

T

b/z0.2 0.3 0.4 0.5 0.6 0.70

0.01

0.02

0.03

0.04

0.05

z/H

T

M/(Bz2)2/3

Two-fluid Q0 = 1.5 l/min

Two-fluid Q0 = 1.0 l/min

Two-fluid Q0 = 0.5 l/min

Experimental

Model and experimental results agree appreciably well

COMPARISON W/MIXED-FLUID MODELCOMPARISON W/MIXED-FLUID MODEL

0.05 0.1 0.15 0.2 0.25 0.3 0.35 0.40

0.01

0.02

0.03

0.04

0.05

z/H

T

Q/(Bz5)1/31.5 2 2.5 3 3.5 4 4.5 50

0.01

0.02

0.03

0.04

0.05

z/H

T

Um

/(B/z)1/3

0.05 0.1 0.15 0.2 0.25 0.30

0.01

0.02

0.03

0.04

0.05

z/H

T

b/z0.2 0.3 0.4 0.5 0.6 0.7 0.8 0.90

0.01

0.02

0.03

0.04

0.05

z/H

T

M/(Bz2)2/3

Mixed-fluid Q0 = 1.5 l/min

Mixed-fluid Q0 = 1.0 l/min

Mixed-fluid Q0 = 0.5 l/min

Experimental

Model overpredicts the velocity of continuous phase and the momentum flux

RESULTS:RESULTS: PIV of unstratified bubble plume successfulPIV of unstratified bubble plume successful

Entrainment coefficient depends on bubble concentrationEntrainment coefficient depends on bubble concentration

Two-fluid models appear to match plume physics better than mixed fluid modelsTwo-fluid models appear to match plume physics better than mixed fluid models

ONGOING WORK:ONGOING WORK:

Combining three different FOV to get better aligned dataCombining three different FOV to get better aligned data

Application of PIV to stratified bubble plumeApplication of PIV to stratified bubble plume

Extending single plume numerical model to double plumeExtending single plume numerical model to double plume

Obtaining appropriate initial conditionsObtaining appropriate initial conditions

FUTURE SCOPE OF WORK:FUTURE SCOPE OF WORK: PIV-LIF Combined study for the bubble plumePIV-LIF Combined study for the bubble plume

Develop LES (Large Eddy Simulation) numerical models Develop LES (Large Eddy Simulation) numerical models

REAL-LIFE SCENARIOS:REAL-LIFE SCENARIOS: Ocean Ocean

Sequestration of Sequestration of Liquid COLiquid CO22 (constitutes (constitutes

64% of global greenhouse 64% of global greenhouse gas emissions)gas emissions)

Other Applications:Other Applications: Aeration of Lake/AquariumsAeration of Lake/Aquariums Fate of oil/chemicals released Fate of oil/chemicals released

in deep sea due to accidental in deep sea due to accidental leakages and blowoutsleakages and blowouts

Bio-medical EngineeringBio-medical Engineering- - blood flow modeling in a ventricular blood flow modeling in a ventricular assist deviceassist device

Chemical industriesChemical industries- - two-phase flow modeling due to two-phase flow modeling due to countercurrent chromatographycountercurrent chromatography

MetallurgyMetallurgy-- gas stirring of molten metals in ladles, gas stirring of molten metals in ladles, in nuclear devices and chemical in nuclear devices and chemical reactorsreactors

References:References:

Asaeda, T. & Imberger, J. (1993), ‘Structure of bubble plumes in linearly stratified environments’, Asaeda, T. & Imberger, J. (1993), ‘Structure of bubble plumes in linearly stratified environments’, J.Fluid Mech.J.Fluid Mech. 249,249, 35-57. 35-57.

Bergmann C. (2004), ‘Physical and Numerical studies on multiphase plumes’, MS Thesis, Dept. of Bergmann C. (2004), ‘Physical and Numerical studies on multiphase plumes’, MS Thesis, Dept. of Civil Engrg,, Coastal & Ocean Engrg. Program, Texas A&M University, College Station, TX.Civil Engrg,, Coastal & Ocean Engrg. Program, Texas A&M University, College Station, TX.

Bergmann C., Seol D.-G., Bhaumik T. & Socolofsky S. A. (2004), ‘Entrainment and mixing properties Bergmann C., Seol D.-G., Bhaumik T. & Socolofsky S. A. (2004), ‘Entrainment and mixing properties of a simple bubble plume’, Abstract # 272, 4th International Symposium on Environmental of a simple bubble plume’, Abstract # 272, 4th International Symposium on Environmental Hydraulics, IAHR, Hong Kong, China.Hydraulics, IAHR, Hong Kong, China.

Lemckert, C. J. & Imberger, J. (1993), ‘Energetic bubble plumes in arbitrary stratification’, Lemckert, C. J. & Imberger, J. (1993), ‘Energetic bubble plumes in arbitrary stratification’, J.Hydraulic J.Hydraulic Engrg..Engrg.. 119119(6), 680-703.(6), 680-703.

McDougall, T.J. (1978), ‘Bubble plumes in stratified environments’, McDougall, T.J. (1978), ‘Bubble plumes in stratified environments’, J.Fluid Mech.J.Fluid Mech. 8585(4), 655-672.(4), 655-672. Milgram, J.H. (1983), ‘Mean flow in round bubble plumes’, Milgram, J.H. (1983), ‘Mean flow in round bubble plumes’, J.Fluid Mech.J.Fluid Mech. 133133, 345-376., 345-376. Morton, B. R., Taylor, S. G. I. & Turner, J. S. (1956), ‘Turbulent gravitational convection from Morton, B. R., Taylor, S. G. I. & Turner, J. S. (1956), ‘Turbulent gravitational convection from

maintained and instantaneous sources’, maintained and instantaneous sources’, Proc. of the Royal Soc.Proc. of the Royal Soc. A234A234, 1-23, 1-23 Schladow, S. G.(1993), ‘Lake destratification by bubble-plume systems: Design methodology’, Schladow, S. G.(1993), ‘Lake destratification by bubble-plume systems: Design methodology’, J. J.

Hydr. Engrg.Hydr. Engrg. 119119(3), 350-368.(3), 350-368. Socolofsky S. A. (2001), ‘Laboratory Experiments of Multi-phase plumes in Stratification and Socolofsky S. A. (2001), ‘Laboratory Experiments of Multi-phase plumes in Stratification and

Crossflow’, Ph.D Thesis, Dept. of Civ. Env. Engrg., MIT, Cambridge, MA.Crossflow’, Ph.D Thesis, Dept. of Civ. Env. Engrg., MIT, Cambridge, MA. Socolofsky, S. A., Crounse, B. C. & Adams, E. E (2002), ‘Multi-phase plumes in uniform, stratified and Socolofsky, S. A., Crounse, B. C. & Adams, E. E (2002), ‘Multi-phase plumes in uniform, stratified and

flowing environments, flowing environments, inin H. Shen, A. Cheng, K.-H. Wang & M. H. teng, eds, ‘Environmental Fluid H. Shen, A. Cheng, K.-H. Wang & M. H. teng, eds, ‘Environmental Fluid Mechanics – Theories and Applications’, ASCE/Fluids Committee, Chapter 4, pp. 84-125.Mechanics – Theories and Applications’, ASCE/Fluids Committee, Chapter 4, pp. 84-125.

Wuest, A., Brooks, N. H. & Imboden, D. M. (1992), ‘Bubble plume modeling for lake restoration’, Wuest, A., Brooks, N. H. & Imboden, D. M. (1992), ‘Bubble plume modeling for lake restoration’, Water Resour. Res.Water Resour. Res. 2828(12), 3235-3250.(12), 3235-3250.

Related Links:Related Links:

http://vtchl.uiuc.edu/basic/r/bp/http://vtchl.uiuc.edu/basic/r/bp/ http://www.dantecdynamics.com/PIV/System/Index.htmlhttp://www.dantecdynamics.com/PIV/System/Index.html http://archive.greenpeace.org/politics/co2/co2dump.pdfhttp://archive.greenpeace.org/politics/co2/co2dump.pdf www.umanitoba.ca/institutes/fisheries/eutro.html www.umanitoba.ca/institutes/fisheries/eutro.html http://bss.sfsu.edu/ehines/geog646/Marine%20Pollution.pdfhttp://bss.sfsu.edu/ehines/geog646/Marine%20Pollution.pdf http://www.sealifesupply.com/aquaria.htmhttp://www.sealifesupply.com/aquaria.htm

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