Performances of closed cycle disk MHD generator with Ar/Cs

Recent experimental results of shock-tube driven disk MHD generators with Ar/Cs are reported. Experiments were carried out under various load conditions, two different stagnation pressures and various seed fractions. Under the present experimental conditions, effects of the load resistance at the nozzle on enthalpy extractions were small. Enthalpy extractions remained small for the single load resistance. Effects of the stagnation pressure on enthalpy extractions were also found to be small. By optimizing seed fractions, enthalpy extractions higher than 20% were achieved for the segmented load resistance. About 35-45% of the inlet stagnation pressure was lost, even in the nozzle, by Joule dissipation and differences of the total pressure loss at each load conditions were small. The pressure loss due to the shock wave was found to be small owing to the low incident Mach number of the flow. Different kinds of discharge structures were found. A circular luminous discharge due to shock waves appeared, even in the nozzle, under open circuit nozzle conditions. For a single load resistance, spoke instability appeared in the nozzle, this being due to the low electrical conductivity of the plasma in the nozzle