Investigation of heat transfer and flow properties in separated flow and reattachment regions for liquid sodium flow at fast reactors


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Karabulut K. , Alnak D. E.

Nuclear Engineering and Design, cilt.379, ss.1-12, 2021 (Diğer Kurumların Hakemli Dergileri)

  • Yayın Türü: Makale / Tam Makale
  • Cilt numarası: 379
  • Basım Tarihi: 2021
  • Doi Numarası: 10.1016/j.nucengdes.2021.111224
  • Dergi Adı: Nuclear Engineering and Design
  • Sayfa Sayıları: ss.1-12

Özet

In many engineering applications, such as heating and cooling systems, flow around an automobile or building,

separation and reattachment regions are formed. These regions are very important for controlling the amount of

heat and mass transfer. Liquid sodium is used as heat transfer fluid in many areas having a high temperature,

especially nuclear reactors. In this work, the effects of flow separation and reattachment on the heat transfer and

flow properties of step corner structures with different chamfer lengths as h/4, h/2, 3 h/4 and h comparing with

and without chamfer (normal) geometry have been numerically investigated in the vertically positioned backward

facing step flow geometry for fast reactors that need to be cooled efficiently. One of the walls behind the

backward facing step has a constant temperature while the others are adiabatic. The results of the work have

been determined by solving steady conservation equations with three dimensional and k-ε turbulence model with

Boussinesq approach using ANSYS-FLUENT computer program. Water and liquid sodium have been employed as

working fluids. The expansion rate of the backward-facing step is 1.5. The study has been carried out at two

different Reynolds numbers: 5000 and 10000. The presented work has been compared with the numerical results

of the study found in the literature and it has been seen that they are compatible and acceptable with each other.

The results have been exhibited as the variations of Nu number, fluid temperature, turbulence kinetic energy and

pressure. Besides, temperature, velocity and streamline distributions have been visualized in backward facing

step flow geometry. For Re = 10000, it has been determined that average fluid temperature increment value of

the backward facing step geometry with h chamfer length in the liquid sodium flow has been 6.54 K higher than

in water.