Page 314 - Thermal Hydraulics Aspects of Liquid Metal Cooled Nuclear Reactors

284 Thermal Hydraulics Aspects of Liquid Metal Cooled Nuclear Reactors

1

0.8

0.6
C t1
0.4

0.2

0
0 2e+07 4e+07 6e+07 8e+07 1e+08
Re*Pr

Fig. 6.2.1.6 Graphical representation of a correlation for C t1 (Shams et al., 2014).
5 6
DNS DNS
Low Re K-epsilon model 5 Low Re K-epsilon model
4
AHFM-2005 AHFM-2005
AHFM-NRG AHFM-NRG
4
3
T + T + 3
2
2
1
1
0 0
1 10 100 1000 1 10 100 1000
y + y +
Fig. 6.2.1.7 Evolution of temperature profile for a channel for Pr¼0.025 at (left) Re τ ¼395 and
(right) Re τ ¼640 (Shams et al., 2014).

The use of this correlation brings significant improvements in the prediction of the
heat transfer for low Prandtl fluids, especially in the forced convection flow regimes.
Fig. 6.2.1.7 displays the evolution of temperature for two different turbulent channel
flows, that is, Re τ ¼395 and 640 at Pr¼0.025. It is clearly noticeable that among the
tested models, the AHFM-NRG has shown significant improvement and displays a
good agreement with the reference DNS database. In addition to the planar channel
flows, the AHFM-NRG was also tested for a turbulent wavy channel flow. Once again,
the AHFM-NRG has shown good agreement with the reference data (Shams et al.,
2014). It is important to realize that even if the performance of this model for the con-
sidered test cases so far has been good, these test cases are fairly simple compared with
the reactor-scale applications. Therefore, the model will need validation with more
test cases and reactor-scale applications. In this respect, further validation of the
AHFM-NRG is foreseen to be performed within the framework of the SESAME
and the MYRTE projects.