Numerical Simulation on Annular Hall Energy Conversion Device under Wide Range of Operating Condition

The characteristics of the annular Hall MHD device under the wide range of operating conditions are investigated in detail by carrying out time-dependent three-dimensional numerical simulations with the purpose of providing fundamental data for the future industrial application of the device. Because of the configuration of the device, it can be operated both as generator and accelerator. Under power extraction, the highest enthalpy extraction of 5% for the load resistance of 3.0Ω and the highest isentropic efficiency of 15% for 2.0Ω are obtained. The nonuniform plasma induced by weak ionization of seed forms a clockwise spiral structure in θ-z plane. Due to this unsteady behavior of the discharge, output electrical power fluctuates periodically at the frequency of approximately 20-40kHz. Finally, the Lorentz efficiency is evaluated under power input. The highest Lorentz efficiency of 58% can be obtained for -0.5kV.