Development of Analytical Method for DC Electromagnetic Flow Coupler including End Effects

To develop an analytical method for a DC electromagnetic flow coupler, an electric circuit analog has been considered. The adopted analog consists of an infinite series of the lumped parameter circuit of the flow coupler cross section and allows an analysis of end effects which appear outside the inlet and outlet of the flow ducts. The ordinary differential equation of the second order was derived for the current distributions from the circuit equations of the present analog. The present method predicted very well the current distributions of the analytical solutions obtained by Birtzvalk et al. for the coupler with infinite width and length.Further, the overall efficiency of the typical flow coupler evaluated by the present method gave a similar dependence on the flow ratio to that of Hughes & Alexion, although differences appeared in the results of the pressure rise and drop in the coupler's two ducts. From the current distributions obtained, these differences were attributed to the electrical coupling of the pump and the generator ducts in the fringing magnetic field which was considered by the present method, but not by Hughes & Alexion. Finally, the current flow patterns are given with an improved distribution of the external magnetic field including the wall effect.