eucass 2009 presentation
TRANSCRIPT
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