Pressure Drop of Spacer Grids in Smooth and Roughened Rod Bundles

Experiments have been performed on the pressure drop of a spacer grid in rod bundles of 12 rods. Both smooth and rough rod bundles were used in the experiments. The artificial roughness cut into the outer surface of the rods was chosen so as to meet the actual design of a gas-cooled fast breeder reactor. The results of this investigation for a Reynolds number range between Re = 4 × 10³ and 7 × 10⁴ indicate that the pressure drop at the spacer grids is higher in a roughened rod bundle than in a smooth rod bundle.