teddy ardiansyah - study on sodium cavitation for fast reactors (iii) analysis of cavitation with...

8/9/2019 Teddy Ardiansyah - Study on Sodium Cavitation for Fast Reactors (III) Analysis of Cavitation with FLUENT and Erosion Experiment

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Study onSodium Cavitation

for Fast Reactors (III)Analysis of Cavitation with FLUENT

and Erosion Experiment

Teddy Ardiansyah, Minoru Takahashi, Makoto Asaba,

Kuniaki MiuraAESJ Annual Meeting

Ibaraki University, Mito, IbarakiMarch 27, 2010

E28


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Background For the development of economic (SFR), reactor

vessel and components are made compact,which leads to fast flow of a coolant.

Cavitation is possible to occur due to fast flow

and low static pressure. Cavitation could lead to a severe damage of the

inner part of the sodium loop system, neutronic

and hydrodynamic problems.

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Purpose

To analyze cavitation in water and liquid

sodium using CFD code as well as erosionphenomena caused by cavitation in liquidsodium for 600 hours.

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Venturi test section

4

Cavitation coefficient

K= cavitation coefficient

= water/sodium densityP0 = downstream static pressure

Pv = water/sodium vapor pressure

V1 = velocity in venturi region

V0 = velocity in downstream region


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Experimental conditions

Sodium

T: 200-400C

Pstag: 0.06-0.18 MPa-a

Water Room temperature

Pstag: 0.06-0.12 MPa-a

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6

Developed cavitation observed by high speed camera (8,000 fps),

Vinlet: 1.514 m/s, Pds: 0.124 MPa-a, 13o

C, K: 0.98


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Numerical calculation of cavitation

Assumptions

The working fluid is liquid and gas phase(vapor and non-condensable gas).

The formation and collapse of bubbles aretaken into account in the model.

The mass fraction of non-condensable gas isknown in advance.

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Numerical calculation (1) Equations used in the calculation

Continuity equation for mixture model

Momentum equation for mixture model

( ) ( ) 0.t

mmm =+

8

( ) ( )

+++

++=+

=

n

k

kdrkdrkkm

T

mmmmmmmm

Fg

pt

1

,,.

..


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Numerical calculation (2) Equations used in the calculation

Energy equation for mixture model

( ) ( )( ) ( ) En

1k

eff

n

1k

kkkkkkk STk.pE.E

t

+=++

= =

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Numerical calculation (3)

Based on full cavitation model by Singhal,

et al. Transport equation of vapor mass fraction,

From generalized Rayleigh-Plesset equation forbubble dynamics with limiting bubble size, Re and

Rc are derived

R

S2

dt

dR

R

4

dt

dR

2

3

dt

RdR

)t(p)t(p

L

L

2

2

2

L

B

++

+=

( ) ( ) ( ) cevmm RRffvf

t+=+

f

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Numerical calculation (4)

When

When

empirical coefficient

vpp ( )

v

l

vvlcc f

3

pp2kCR

=

( )( )gv

l

vvlee ff1

3

pp2kCR

=

02.0Ce = 01.0Cc =

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Calculated condition

No slip velocity (vl-vg=0)

Non-condensable gas fraction:

Sodium: 1, 3, 9 ppm (argon)

Water: 9, 15 and 45 ppm (air) Boundary condition:

fixed inlet velocity and fixed outlet pressure

(based on experimental measurements)

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14

12 13 14 15 16

0.9

1

1.1

1.2

1.3

Venturi velocity (m/s)

K(-

)

Sodium 400CPstag: 0.141 MPa-a (exp)

No cavitation (experiment)Cavitation (experiment)

12 13 14 15 16

0.9

1

1.1

1.2

1.3


K(-

)

Beta: 1 ppmSodium 400C

No cavitation (calculated)Cavitation (calculated)

Experiment Calculated

10 15 200

1

2

3


K(-

)

Water 10.8-13.0CPstag: 0.062 MPa-a (exp)

No cavitation (experiment)Cavitation (experiment)

10 15 20

0

1

2

3


K(-

)

Beta: 45 ppmWater 10.8-13.0C

No cavitation (calculated)Cavitation (calculated)


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Contours of void fraction in sodium for K: 0.92;T: 400C; and 3 ppm of non-condensable gas.


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Erosion experiment Temperature of sodium: 200C

Flow rate: 27~28L/min

Pressure: 0.05~0.1Kg/cm2 (at expansion

tank) Total: 600 hours

K: 0.59~0.51 (developed cavitation)

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X-ray of venturi test section (left) andcutted parts of test section (right).


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Optical micrograph (up) and SEM of the test section(bottom).

No.6 x 50 No.7 x 100

No.6 Outlet No.6 Outlet No.6 Outlet100m 100m 30m


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Conclusion Onset cavitations are influenced by non-

condensable gas. Non-condensable gas fraction in liquid

sodium is lower than in water because ofthe different solubility.

Erosion occurred at downstream of the

test section in sodium cavitation for 600 h.

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Thank You for

Your Attention.

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