Investigation of Coupling MHD Rectangular Ducts Flows Based on a Fully Developed Modeling

Liquid metal magnetohydrodynamic (MHD) flows through the electrical coupling rectangular ducts are investigated based on a fully developed modeling. Numerical simulations of four different coupling MHD duct flows are carried out to get the results of the MHD pressure drop and the velocity distribution. The first and second cases are that the coupling rectangular ducts are arranged along the direction of external magnetic field, the flow direction in the two ducts is the same in case 1 but it is opposite in case 2; in the third and fourth cases, another coupling duct is extended along the perpendicular direction of the external magnetic field, the flow direction is identical in case 3, but it is opposite in case 4. Numerical results of the velocity and the induced electrical current distributions in the cross sections of the coupling ducts are given in those four different cases, it is indicated that the external magnetic field has a different effect on the flow pattern in those four cases. The MHD pressure drop in those four different cases is compared with the result of one normal rectangular duct flow, the MHD pressure drop of case 1 is reduced compare with the result of one normal duct MHD flows and result of case 4 is closed to one normal duct case, but the results of cases 2 and 3 are larger than it, especially for case 2 it is several times larger than the result of one normal duct flow. In addition, the MHD pressure gradients in those four cases decrease with the increase of the wall conductance ratios when the other conditions are the same. In the case, the three coupling duct flows when the flow direction of the middle duct is opposite, the strong magnetic field has very significant effect on the flow pattern in the middle coupling duct, and the MHD pressure gradient in the middle duct can be dozens of times bigger than that of one normal single duct flow. These results should be considered in the future liquid blanket design.