General characteristics of MHD machines

Yu. P. Ushakov

Abstract
The energy characteristics η = f(∆p, Q) of induction and series- and independently excited convection MHD machines are analyzed in the pump operating mode. The analysis applies also to the power generation mode as well as to shielded electric motors. It is shown that maximum possible efficiency is obtained at a definite value of magnetic induction always below the saturation induction of the magnetic system. The ratio of optimum to saturation induction is either 2/3 or 3/4 depending on the magnetizing function approximation. The mathematical model can be improved if the assumption of constant temperature is replaced by functions that take into account the variations of the temperature of basic structural elements of the machine (the active medium, channel walls, and magnetic system) with its operating conditions.