An Experimental Correlation of Cross-Flow Pressure Drop for Triangular Array Wire-Wrapped Rod Assemblies

An experimental study was carried out to quantitatively estimate the lateral drag changes due to flow structure alteration caused by the presence of wire-wrap spacers in liquid-metal fast breeder reactor rod assemblies. Specially designed test rod bundles were constructed employing vertical straight wires attached at various angles around the rods relative to the cross-flow direction. These bundles simulate the cross-flow pressure drop within a control volume with axial mesh size less than one-twelfth of wire-wrap lead length. The variables examined were wire angular positions, Reynolds number, and rod arrangements. The transverse pressure drop data for triangular-array rod bundles with wires have been correlated throughout the laminar and turbulent flow regimes. The correlation is in the form of a correction parameter to be applied to the friction factor-Reynolds number relationship for the corresponding bare rod bundle.