Liquid-Metal Faraday-Type MHD Generators

The use of a liquid metal as the working fluid in magnetohydrodynamic (MHD) generators is considered and possible energy conversion applications for this type of generator are briefly reviewed. A simple model of the Faraday-type generator is developed and used to obtain relations giving generator terminal voltage, pressure drop, and efficiency. The generator performance is shown to depend oti a magnetic Reynolds number based on the length of the generator duct and, also, on the ratio of machine internal resistance to electric load resistance. The existence of an effect analogous to armature reaction in conventional machines is deduced and the use of compensating conductors to overcome it is discussed. The problems of generator design are considered and examples are used to illustrate the effect of losses in a practical generator. It is concluded that compensation is necessary in all but the smallest machine sizes.