Numerical and experimental studies of MHD flow in a rectangular duct with a non-conducting flow insert

We consider magnetohydrodynamic (MHD) flows in a conducting rectangular duct with a non-conducting flow channel insert (FCI) in a constant transverse magnetic field. The computations based on the fully developed flow model are performed for three FCI modifications: (i) without pressure equalization openings, (ii) with the pressure equalization slot (PES) in the FCI wall parallel and (iii) perpendicular to the applied magnetic field. The computed flow patterns and the current circuits in the duct with the FCI are analyzed. The experiments are performed with In-Ga-Sn as a work fluid flowing in an outer rectangular duct made of stainless steel with the FCI made of epoxy for two cases: FCI with the PES, and with the pressure equalization holes (PEH), both made in the FCI wall parallel to the magnetic field. The experiments have confirmed significant reduction of the MHD pressure drop due to the flow insert (larger reduction in the case of PEH) compared to the non-insulated duct, but the experimental MHD pressure drop is different (larger) than the computed one. This difference is discussed and further modifications of both the flow model and the experiment are suggested.