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This relationship gives the ratio of the averages
of the- velocities at the two stations farthest from
the inlets to the averages of the velocities at the
two stations nearest the inlets. The relationship
for the flow distribution when only one pump was
operating was defined as
- -
'3 pump A '1 pump B
Q, V, [ operating + ] [operating]
-t
QtJ 2
Some of the experimental results are presented
in Fig. 4.1.2 in terms of these relationships.
-
The predicted flow distribution in the ART system
ORNL-LR-DWG (4739
f.08
I .06
OC
3
! .04
i .02
4.00
to4 2 5 I d
REYNOLDS MODULUS AT MIDPLANE
Fig. Flow Distribution in
Reflec e Shell Annulus.
PERIOD ENOfNG JUNE 10, 1956
was obtained by extrapolating the data to the
Reynolds numbers for the actual system at the
mid-plane of the annulus. A summary of the
results is given in Table 4.1.1.
The minimum flow rate was found in the portions
of the annulus nearest the inlets, while the maxi-
mum flow rate was observed in the portions
farthest away. These conditions are the reverse
of those anticipated, and a possible explanation
is that the fluid entering the annulus from the
inlet header must abruptly change direction and
it probably undergoes high velocity losses, particu-
larly near the inlet to the annulus where the
momentum is the greatest. After the model inlet
header used in these experiments had been fabri-
cated, the design of the actual ART sodium system
was modified so that uniform distribution of sodium
flow would exist in the annulus if there were no
eccentricities. The flow in such a concentric
annulus will be axial; that is, there will be no
spiraling, Studies of the motion pictures of the
flow in the model indicated that, for a constant
pump pressure, the average velocity fluctuation at
any point in the annulus would probably be less
than k5%.
The flow distributions in the annulus for two
possible conditions of eccentricity of the core
shell were also studied. Buckling of the core
shell between the spacers was simulated to
produce a local eccentricity. Since the reduction
in flow as a function of the reduction in flow area
was the prime concern, the buckling of the core
shell was simulated by adding pieces of tape,
as shown in Fig. 4.1.3. For a local reduction in
annulus thickness of 50% (t/to = 0.5), the flow
from inlet to outlet through that sector of the
annulus was 7% of the average flow.
Radial eccentricity was also simulated to study
the effect of a slight canting of the core shell on
TABLE CT.1. SUMMARY OF CONCENTRIC ANNULUS FLOW DISTRIBUTION STUDIES
Annulus width, In.
Reynolds modulus at mid-plane
0.386 1.00 0.609 1.00
For two pumps operating 1.045 1.025 1.025 1.02
Far one pump operating (70% normal flow assumed) 1.08 1.06 1.075 1-07
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