Evolution of the Boundary Layer Near the Walls of an MHD Generator

The laminar temperature and velocity profiles near a plane rectangular surface (conducting or insulating) were studied for a given free supersonic flow; the case of a Faraday generator was examined. The equations of mass, momentum and energy conservation for the region near a wall were solved numerically after transformation of the system of partial derivative equations into a system of differential equations. The authors considered the case of a compressible fluid whose thermodynamic and electrical properties are functions of temperature and pressure. The free flow was defined by the evolution of velocity, temperature and Mach number and the derivatives of these quantities in relation to an abscissa taken parallel to the duct axis. In this way it is possible to study (without seeking similar solutions) the influence of electromagnetic phenomena on the shape of the velocity and temperature profiles in the boundary layer as a function of the abscissa. More specifically, a breakaway is shown to occur in the neighbourhood of the conducting wall, and the first approximation to a criterion is obtained. (author)