Page 230 - Thermal Hydraulics Aspects of Liquid Metal Cooled Nuclear Reactors

Subchannel analysis for LMR 201

Sweeping flow shape varying with angle
0.3
CFD simulation
Proposed correlation
Wantland (1974)
0.2
Normalized transverse velocity –0.1

0.1

0

–0.2

–0.3
0 p/3 2p/3 p 4p/3 5p/3 2p
Wire position angle

Fig. 5.9 Normalizedtransverseflowdistributionshapeinaxialdirection(WangandCheng,2017).

Turbulent mixing
Turbulent mixing describes the transversal exchange resulted by the turbulent fluctu-
ation of thermal-hydraulic parameters such as velocity and temperature or enthalpy, as
schematically indicated in Fig. 5.10.
To describe the turbulent mixing, the coefficient β is introduced, which is defined
as the ratio of the magnitude of the velocity fluctuation in the gap to the main velocity
averaged in both subchannels:

u′ i,j

Fig. 5.10 Velocity fluctuation at the gap.