Swirling spacer grids in a model of nuclear fuel assembly - PIV data of isothermal flow

The swirl grid produces longitudinal vortices , which decay much slowlier than general grid-generated turbulence. This effect has been demonstrated for square lattice of such generated vortices without any fuel rods, see the article https://doi.org/10.1063/5.0207124. The idea of this experiment is to apply these effect to the case of nuclear fuel assembly, where are used special mixing grids enhancing mixing of hot coolant at the boundary layers of the fuel rods with the cooler liquid in the inter-rod channel centers. However, this mixing efficiency decreases fast, while the longitudinal vortices shift the decay far downstream.

The database contains PIV vector fields of the wind tunnel test of isothermal flow through a model of nuclear fuel assembly. The model is upscaled, hence the diameter of the fuel rods is 42.2 mm (real is 9.1 mm), the distance of fuel rods (the mesh parameter M) is 59.1 mm (real is 12.75 mm). The fuel rods are physically modeled by using water pipes of length 3 m, 5 spacer grids are placed in total. The following configurations are tested:
- all grids just base spacer grids (name e.g.: "U20ms-base-z02")
- the last grid before the PIV plane contains the swirling elements of Rossby number 2.5 (name e.g.: "U20ms-1vir4-z02")
- the last two grids are the swirler grids with oppositely oriented swirling elements (name e.g.: "U20ms-2vir4-z02")
- only single swirl grid without fuel rods and without any other grids (name e.g.: "U20ms-1pv4-z02")
All test are performed with atmospheric air at velocity 20 m/s. The last number in the name ("...-z04") is the distance from the PIV plane to the last grid in multiples of M; there are 5 distances: 0.5, 1, 2, 3 and 4. The PIV plane is perpendicular to the rod axis. PIV is in stereo configuration with two cameras. If some author is interested to process our image data by his/her own method, we are open to share the original images (638 GB), contact us.