Analyse the disk closed cycle MHD generator performance with the influence of channel characteristics

Abstract

The enthalpy extraction ratio is one of the most significant parameter of a disk closed cycle MHD generator. There are two methods to improve the enthalpy extraction, those are the increase of channel cross-sectional area ratio and the implementation of inlet swirl. In this study, the mechanism of enthalpy extraction improvement has been confirmed by the two-dimensional numerical calculation. As a result, by increasing the channel cross-sectional area ratio of the disk MHD generator, the increase of static pressure and the velocity deceleration can be suppressed due to the Lorentz force, and it is possible to maintain a high flow velocity inside the channel and a high Hall parameter. The implemention of inlet swirl is possible to maintain a low static pressure inside the channel and the enthalpy extraction ratio rises due to the increase of Hall parameter. In addition, the channel cross-sectional area ratio increases due to the swirl implementation, the static pressure is kept low, and the channel inlet flow velocity increases. This also leads to the increase of enthalpy extraction ratio, that is the increase of output power.