Effect of duct quantity on the magnetohydrodynamic flow state through multiple electrically coupled ducts

The magnetohydrodynamic (MHD) flow state in multiple electrically coupled ducts for liquid metal blankets is investigated to accurately predict the effect of duct quantity on pressure distribution, with further consideration of duct aspect ratio and arrangement. We conducted three-dimensional numerical simulations to analyze 1 × n and m × n matrix of duct systems in both co-flow and counter-flow configurations. For 1 × n duct systems, the pressure drop (Δp) can be reduced to 60% of that observed in a single duct when n = 10 under co-flow configurations. We further propose a mathematical model that accurately predicts the pressure gradient as a function of n for co-flow systems. In counter-flow cases, Δpmax decreases with increasing odd n greater than 2, whereas an opposite trend is observed when n is even for b/a ≤ 1. When b/a > 1, the coupling pressure drops increase with n. Δpmax reaches over 60 times that of a single duct among all cases in this study. In order to mitigate excessive MHD coupling pressure drop in counter-flow configurations, we design a new structure with different slot layouts on each coupling Hartmann wall, which is effective in reducing the pressure drop within multi-coupled ducts. We analyze the results of m × n matrix duct systems, indicating that placing the inlet on opposite sides can prevent an increase in pressure drop caused by adding n perpendicular to the magnetic field in counter-flow configurations when n is even. These findings will provide valuable physical insights for the application of multi-coupled ducts in liquid blanket systems.