Numerical Simulation of Blow-Down Closed-Cycle Disk MHD Generator

Abstract

Numerical simulations of the closed-cycle disk MHD generation experiment with TIT (Tokyo Institute of Technology) Fuji--1 blow-down facility are performed. In the calculations, the r--z two-dimensional time-dependent simulation code developed by the authors that can take the effect of water contamination into account is used, and the experimental conditions of Run A4109 operated by Disk--F4 generator are selected as the numerical conditions. When the water contamination is the lowest level realized in the experiments, the simulation results coincide with the experimental results reasonably well, though there exist some discrepancies caused by inaccuracy of used basic plasma parameters, limitations of the two-dimensional approximation, etc. The voltage-current curve is almost linear, indicating that the MHD interaction is relatively weak and the flow field is mainly determined by the back pressure. The increase of the water contamination level results in the decrease of the seed ionization rate at the generator channel inlet, leading to the steep deterioration of the generator performance.