Preliminary Design Procedure for High Power Density MHD Generators

摘要

The steps to be taken in the preliminary design of a high power density, segmented Faraday or diagonal, open-cycle MHD generator are formalized. The recommended design procedure starts with the optimum choice of the combustion chamber pressure. The optimization is based on a semi-empirical expression of the effective power density, developed by Smith and Nichols. As a result of this optimization, a rough estimate of the realizable power density is made, which yields the order of magnitude of the transverse dimension keeping the length-to-diameter ratio around 10 for the desired power output. It is then recommended that the area variation and length be calculated on the basis of an isothermal core flow. This preliminary shape of the duct will serve as the base on which alterations can be made by a computer to accommodate wall effects in detailed design stage that will follow the preliminary consideration. An alternate route for the preliminary design is provided by using scaling laws. Starting with a well-designed generator which is demonstrably high in power density, dynamically similar units can be produced using these laws. The laws are developed following the modern procedure of ordering. Numerical examples are provided to illustrate the procedure.