eucass 2009 presentation

Large‐EddySimula0onofTranscri0calRoundJets

T.Schmi<,A.Ruiz,L.Selle,B.Cuenot

July 6-9 2009 1 EUCASS 2009

Introduction

July 6-9 2009 EUCASS 2009 2

Temperature

Pressure

cT

cPSolid

Gaseous

Liquid

Modelingofsupercri4calflowsischallenging:•  Nonlinearequa0onofstate(EOS)•  Complextransportphenomena(SoretandDufoureffects)•  Rapidvaria0onofthermodynamicproper0es•  Largedensitygradients(withoutsurfacetension)

OUTLINE

I.  Supercritical fluids

II. Flow configuration of the present simulation

III. Results

Supercritical Fluids

Oschwald, CST 2006

Goingbeyondthecri0calpressurechangesatomiza0on

Drops=>Finger‐likestructures(nomoresurfacetension)

Temperature

Pressure

cT

cPSolid

Gaseous

Liquid

Supercritical Fluids

July 6-9 2009 EUCASS 2009 5

Fromthemolecularpointofview:

Low-density gas : the distance between molecules is large enough to neglect electromagnetic interactions

High-density gas: Van Der Waals forces must be taken into account

TowardPerfectGas

r

6

Fromthemesoscopicpointofview

PengRobinson(1976)EOS

Supercritical Fluids

July 6-9 2009 EUCASS 2009 7

“Standard”Navier‐Stokesequa0onsforcompressibleflows

EOS

Moleculartransport

Supercritical Fluids

July 6-9 2009 EUCASS 2009 8

TransportCoefficients

RG

PG

RG

PG

Chungetal.(1984)methodisusedforpredic0onofviscosityandthermalconduc0vity

OUTLINE

I.  Supercritical fluids

II. Flow configuration of the present simulation

III. Results

Flow configuration

10

Supercri4cal

T(K)

P(bar)

Solid

Gaseous

Liquid

Tc=126.2

Pc=33.96

300140

40

ReservoirTranscri4cal

N2at40barMayeretal.(2003)

Flow configuration

July 6-9 2009 EUCASS 2009 11

Tin=127Kρ=435kg/m3

Tin=137Kρ=171kg/m3

N2at40barMayeretal.(2003)

Tamb=300Kρ=45kg/m3 Supercri0cal

Transcri0cal

5m/s

12 [1] Colin and Rudgyard, J. Comp. Phys, 162, 338-371 (2000) [2] Nicoud and Ducros, Flow Turb. Comb., 62, 183-200 (1999)

• Explicit3rdorderscheme[1]• WALEturbulencemodel[2]•  Δx=0.1mm• N=5.5Mcells• Re=150000

AVBPsolver(CERFACS):• Unstructuredmesh• Massivelyparallel• Compressiblereac0veflows

2,2mm

250mm

122mm

OUTLINE

I.  Supercritical fluids

II. Flow configuration of the present simulation

III. Results

Results

July 6-9 2009 EUCASS 2009 14

1–Growthofsmallvelocityperturba0ons

2–Vortexroll‐up.Transi0onregion

3–Fully‐developedturbulence.Self‐preservingjets?Real‐gaseffects?

1 2 3

Results

Supercri0cal

Transcri0calMean Centerline Density ComparisonwiththeexperimentaldataofMayeretal.(2003)obtainedwithRamansca<ering

• Densecorelength:Transcri0cal=8DiametersSupercri0cal=5Diameters

15

Simula0onExp.data

Results

July 6-9 2009 16 EUCASS 2009

Transcri0cal

Supercri0cal

Results Radial velocity perturbations along the mixing layer

July 6-9 2009 17 EUCASS 2009

1.2

0.8

0.4

0.0

u' r [

m/s

]

1050 x/d

TRANSCRITICAL SUPERCRITICAL

0D 5D

Results

Transcri4cal

Supercri4cal

Instantaneouswrinklingofthesurface

July 6-9 2009 EUCASS 2009 18

1210

8642

Surf

ace

/ Vo

lum

e [1

/mm

]

1050 x/d

TRANSCRITICAL SUPERCRITICAL

Thewrinklingofthesurfaceinthesupercri0calcaseenhancesheattransfer

6420

-2-4

Budg

et /

(ui

nj/d

)3

1.61.41.21.00.80.6y / rinj

6420

-2-4

Budg

et /

(ui

nj/d

)31.61.41.21.00.80.6

y / rinj

Enstrophy budget

Stretching Dilatation Baroclinic torque Dissipation

19

Transcri4cal Supercri4cal

20

1 ([1])1.4 ([1])4 ( Present)8 ([2])10 (Present)

Fullydeveloppedturbulence

Normaliza0onbyeffec0vediameters

[1] Chassaing, PhD dissertation, INP Toulouse (1979) [2] Zong, PhD dissertation, Penn. State University (2005)

Results

July 6-9 2009 EUCASS 2009 21

Fullydeveloppedturbulence

1.4 ([1])4 ( Present)8 ([2])10 (Present)

• Density and velocity profiles are self-preserving as in low pressure jets. Different behaviour than in Zong (2005)

Conclusions

July 6-9 2009 EUCASS 2009 22

•  Derivation of the LES framework for supercritical flows •  Implementation in the AVBP unstructured parallel LES solver •  Application to an experimental setup

•  Quantitative agreement with available experimental data for a nitrogen jet •  Similarity of centerline velocity and density as in low-pressure jets

23 July 6-9 2009 EUCASS 2009

Thankyouforyoura<en0on