In order to accurately predict the friction pressure drop characteristics of liquid lead bismuth in the cross-section of the fuel assembly rod bundle, a suitable friction pressure drop model should be selected.

This study aims to investigate Friction pressure drop model for wire-wrapped rod bundles in full flow.

Eight different frictional pressure drop models within wire-wrapped rod bundles were evaluated their applicability by using statistical analysis. The prediction accuracy of experimental data from different models in different flow regimes was explored corresponding to laminar flow, transitional flow, and turbulence.

The analysis results show that the friction coefficient is not only related to the number of rod bundles (Nr) and the pitch-to-diameter ratio (P/D), but also related to the wire lead length-to-diameter ratio (H/D). The modified BDD model in the laminar flow range and this work model are more consistent with the experimental data. The modified BDD model, CTD model and this work model are relatively consistent with the experimental data in the transition flow range. The Rehme model, the UCTD model and this work model in the turbulent range are more consistent with the experimental data.

Therefore, the model presented in this study is suitable for predicting friction pressure drop in the cross-section of the fuel assembly bundle in the full flow state.