Fluid Mechanics with Helium: A Few Examples Bernard Castaing - - PowerPoint PPT Presentation

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Fluid Mechanics with Helium: A Few Examples Bernard Castaing ENS-Lyon CERN Turbulence 2007 p. 1 Outlook I- Mini-jet: CRTBT (Grenoble) II- GReC Experiment: CRTBT, LEGI (Grenoble), CERN III- Combustion experiment: CRTBT CERN

SLIDE 1

Fluid Mechanics with Helium: A Few Examples

Bernard Castaing ENS-Lyon

CERN Turbulence 2007 – p. 1

SLIDE 2

Outlook

I- Mini-jet: CRTBT (Grenoble) II- GReC Experiment: CRTBT, LEGI (Grenoble), CERN III- “Combustion” experiment: CRTBT

CERN Turbulence 2007 – p. 2

SLIDE 3

Mini-jet Experiment

Bernard HEBRAL Benoît CHABAUD Joachim PEINKE Francesca CHILLA Antoine NAERT Olivier CHANAL Bruno BAGUENARD

CERN Turbulence 2007 – p. 3

SLIDE 4

Mini-jet Experiment

CERN Turbulence 2007 – p. 4

SLIDE 5

Mini-jet Experiment

Velocity sensor: a hot wire (see later) Main advantages: A wide range of Reynolds numbers:

80 < Rλ < 1100

CERN Turbulence 2007 – p. 5

SLIDE 6

Mini-jet Experiment

Velocity sensor: a hot wire (see later) Main advantages: A wide range of Reynolds numbers:

80 < Rλ < 1100

With constant “boundary” dimensions: Constant integral scale .... but also “spurious” scales: sensor’s size and resolution, etc

CERN Turbulence 2007 – p. 5

SLIDE 7

Mini-jet Experiment

Velocity statistics: Time differences: δv = v(t + τ) − v(t) Taylor Hypothesis: Time τ ⇐

⇒ distance r = V τ

CERN Turbulence 2007 – p. 6

SLIDE 8

Mini-jet Experiment

Velocity statistics: Time differences: δv = v(t + τ) − v(t) Taylor Hypothesis: Time τ ⇐

⇒ distance r = V τ

Moments order p: < δvp > (Structure function) Flatness: <δv4>

<δv2>2 ... etc

CERN Turbulence 2007 – p. 6

SLIDE 9

Mini-jet Experiment

Velocity statistics: Time differences: δv = v(t + τ) − v(t) Taylor Hypothesis: Time τ ⇐

⇒ distance r = V τ

Moments order p: < δvp > (Structure function) Flatness: <δv4>

<δv2>2 ... etc

Power laws ⇐

⇒ plateaus in d ln<δvp>

d ln r

CERN Turbulence 2007 – p. 6

SLIDE 10

Mini-jet Experiment

CERN Turbulence 2007 – p. 7

SLIDE 11

Mini-jet Experiment

Collaboration:

A. Arnéodo, J.F

. Muzy, J. Delour, L. Chevillard Two important results: Frisch and Vergassola effect:

< δv4 > comes to a viscous behaviour

at smaller scales than < δv2 >

CERN Turbulence 2007 – p. 8

SLIDE 12

Mini-jet Experiment

Collaboration:

A. Arnéodo, J.F

. Muzy, J. Delour, L. Chevillard Two important results: Frisch and Vergassola effect:

< δv4 > comes to a viscous behaviour

at smaller scales than < δv2 > Two points correlations: Differences between Taylor and true Euler sampling

CERN Turbulence 2007 – p. 8

SLIDE 13

Mini-jet Experiment

Euler

v(x,t) v(x+r,t) r

Taylor

v(x,t) τ Vτ v(x,t− )

CERN Turbulence 2007 – p. 9

SLIDE 14

GReC Experiment

S. Pietropinto
Y. Ladam
B. Hébral
C. Baudet

P . Lebrun

B. Chabaud
Y. Gagne
O. Pirotte

P . Roche

C. Poulain

J.P . Dauvergne

CERN Turbulence 2007 – p. 10

SLIDE 15

GReC Experiment

Mini-jet: up to 4g/s GReC: up to 300 g/s

CERN Turbulence 2007 – p. 11

SLIDE 16

GReC Experiment

Mini-jet: up to 4g/s GReC: up to 300 g/s GReC:

1200 < Rλ < 6000

CERN Turbulence 2007 – p. 11

SLIDE 17

GReC Experiment

CERN Turbulence 2007 – p. 12

SLIDE 18

GReC Experiment

CERN Turbulence 2007 – p. 13

SLIDE 19

GReC Experiment

To make short: Good points: Characteristics of the flow, Laboratory conditions Signal to noise ratio (> 80dB)

CERN Turbulence 2007 – p. 14

SLIDE 20

GReC Experiment

To make short: Good points: Characteristics of the flow, Laboratory conditions Signal to noise ratio (> 80dB) Bad point: Fabrication of the sensor

CERN Turbulence 2007 – p. 14

SLIDE 21

GReC Experiment

CERN Turbulence 2007 – p. 15

SLIDE 22

“Combustion” experiment

Yves Ladam Pierre Thibault Etienne Wolf Laurent Puech

CERN Turbulence 2007 – p. 16

SLIDE 23

“Combustion” experiment

Cryogenic Rocket Engines: Coaxial injection of H2 and O2 (Critical, 5MPa, 90K)

CERN Turbulence 2007 – p. 17

SLIDE 24

“Combustion” experiment

Cryogenic Rocket Engines: Coaxial injection of H2 and O2 (Critical, 5MPa, 90K) O2

→

Critical He (220kPa, 5K)

CERN Turbulence 2007 – p. 17

SLIDE 25

“Combustion” experiment

Cryogenic Rocket Engines: Coaxial injection of H2 and O2 (Critical, 5MPa, 90K) O2

→

Critical He (220kPa, 5K) H2

→

80K He Same density ratio, close Re, Ma, ... etc numbers. Mixing probed by the temperature.

CERN Turbulence 2007 – p. 17

SLIDE 26

“Combustion” experiment

H O H2

2 2

80K 80K He 5K

CERN Turbulence 2007 – p. 18

SLIDE 27

“Combustion” experiment

CERN Turbulence 2007 – p. 19

SLIDE 28

“Combustion” experiment

Experiments with classical fuel, and air, found droplets far downstream

CERN Turbulence 2007 – p. 20

SLIDE 29

“Combustion” experiment

Experiments with classical fuel, and air, found droplets far downstream Helium experiment: no droplets?!

CERN Turbulence 2007 – p. 20

SLIDE 30

“Combustion” experiment

Experiments with classical fuel, and air, found droplets far downstream Helium experiment: no droplets?! H2/O2 flame (3000K): no droplets either. Crucial parameter: (Flame temperature)/(“Liquid” Tc) : Classical fuel: 1600

400 = 4;

H2/O2: 3000

90 = 33;

He: 80

5 = 16

CERN Turbulence 2007 – p. 20

SLIDE 31

To conclude

CERN Turbulence 2007 – p. 21

SLIDE 32

To conclude

Wide ranges of Re, Ra, ...etc are at least as important as large values.

CERN Turbulence 2007 – p. 21

SLIDE 33

To conclude

Wide ranges of Re, Ra, ...etc are at least as important as large values. CERN: Large sizes (and corresponding large flows), with laboratory conditions. “Easy” use of Helium.

CERN Turbulence 2007 – p. 21

SLIDE 34

To conclude

’Easy’ thanks to: P . LEBRUN, O. PIROTTE, J.-P . DAUVERGNE

S. KNOOPS , R. VAN WEELDEREN, A. BEZAGUET, L.

TAVIAN, N. DELRUELLE, M. PEZETTI And several other helpful and highly qualified people

CERN Turbulence 2007 – p. 22

SLIDE 35

To conclude

Wide ranges of Re, Ra, ...etc are at least as important as large values. CERN: Large sizes (and corresponding large flows), with laboratory conditions. “Easy” use of Helium. (As easy as Air or Water)

CERN Turbulence 2007 – p. 23

SLIDE 36

To conclude

Wide ranges of Re, Ra, ...etc are at least as important as large values. CERN: Large sizes (and corresponding large flows), with laboratory conditions. “Easy” use of Helium. (As easy as Air or Water) Needs for a wide collaboration on sensors: towards robustness and variety (hot-wire, PIV, LDV, Acoustics, ...)

CERN Turbulence 2007 – p. 23

SLIDE 37

To conclude

Wide ranges of Re, Ra, ...etc are at least as important as large values. CERN: Large sizes (and corresponding large flows), with laboratory conditions. “Easy” use of Helium. (As easy as Air or Water) Needs for a wide collaboration on sensors: towards robustness and variety (hot-wire, PIV, LDV, Acoustics, ...) And a long term reflexion on tractable problems: Mixing, Clusterization, Boundary layer detachment and control, Combustion(?) ...

CERN Turbulence 2007 – p. 23