Influence of Inlet Ionization Degree on Performance of Seed-free MHD Generator

Abstract

Power generating characteristics of seed-free linear shaped Faraday type and disk shaped Hall type MHD generators are examined by two-dimensional numerical simulation with changing the inlet ionization degree. A liner shaped Faraday type generator can get stable and high power output at high inlet ionization degree. The net enthalpy extraction ratio, however, is reduced owing to the increase in the required preionization power. At low inlet ionization degree, on the other hand, ionization instability occurs and the enthalpy extraction ratio decreases. A disk shaped Hall type generator can get high net enthalpy extraction ratio even at low inlet ionization degree under a low preionization power. The net enthalpy extraction ratio decreases for an excessive inlet ionization degree because of a strong MHD interaction.