An adiabatic water-air 8×8 fuel bundle loop has been designed and built to gather CFD-grade experiments on two-phase distributions taking into account the effect of:
  • grid spacers and mixing vanes;
  • partial length rods;
  • asymmetric inlet void-fraction distributions.

Fuel bundle characteristics:

  • Liquid superficial velocity = 1 m/s
  • Gas superficial velocity = 10 m/s
  • Individual gas injection for each rod

The experimental facility includes independent gas injections for each individual rod, provides sufficient liquid and gas flow-rates to achieve a full range of flow regimes from bubbly to annular, and can allow to investigate among others the effect on void-fraction distribution due to grid spacers mixing vanes, partial length rods, and asymmetric gas injection.


Individual spargers are mounted at the inlet of each rod to model air bubbles ejected by the rod walls. The spargers are organized into 5 groups, each with its own individual gas supply. The arrangement allows to reproduce asymmetric inlet gas injections.

In the videos below, flow patters around a fuel bundle rod can be observed for high and low gas injections.

High gas injection

Low gas injection


Here below are some videos taken for different gas injections