Interaction of fluid dynamics phenomena and generator efficiency in two-phase liquid-metal gas magnetohydrodynamic power generators

The potential loss mechanisms of a two-phase (liquid-metal and gas) magnetohydrodynamic (LMMHD) electric power generator (which has the advantages of extreme design simplicity, reliability, potentially high isentropic and cycle efficiency, high power density, and the possibility of operation at moderately elevated temperatures) are discussed as they relate to various fluid dynamic phenomena, such as effects resulting from velocity slip, vorticity generation and suppression by the magnetic field wall friction, and shunt currents in liquid boundary layers. The relative importance of these effects is discussed in relation to experimental data on internal flow phenomena, and to known theory. The major source of loss was found to be slip loss, which results from a churn-turbulent flow pattern. A means of creating a stable, homogeneous foam flow with almost no slip, using the surface active properties of liquid metals, is presented. Means of reducing wall shunt and frictional losses are suggested, and the effects of end losses in two-phase flows are described.