Numerical Simulation of Performance of High-Temperature Inert Gas Plasma Faraday-Type Magnetohydrodynamic Generator

摘要

Two-dimensional numerical simulations have been carried out with the objective of explaining the experimentally observed performance of a shock-tunnel-driven, high-temperature inert gas plasma Faraday-type magnetohydrodynamic generator with segmented electrodes. A maximum enthalpy extraction ratio of 13.1% is estimated for a load resistance of 1.0 Ω, which agrees well with the experimental result (12.9% for 1.0 Ω). Current concentration at the upstream edges of the anode and the downstream edges of the cathode, which is due to the Hall effect, is successfully simulated. A large voltage drop is caused in the vicinity of the electrodes, which is attributed to a large Hall parameter arising due to the decrease in the electron number density in the region of the boundary layer. The plasma structure is streaky and unstable at an inlet total temperature of 7500 K; the structure becomes stable with an increase of inlet total temperature to 9000 K. Suppression of ionization instability can be attributed in part to the weakness of the dependency of the electrical conductivity on the electron number density as coulomb collision of electrons become dominant at higher inlet total temperatures.