Search

Numerical analyses of the experimental-scale scramjet engine driven magnetohydrodynamics generator implemented in the Hypersonic Vehicle Electric Power System project have been carried out to clarify plasma behaviors and power generation characteristics. Three-dimensional numerical analyses have been performed under the two inlet conditions: one is the uniform inlet temperature condition, and the other is the nonuniform inlet temperature condition. Under the nonuniform inlet temperature condition, the generator performance approximately agrees with the experimental result. The tendency of the voltage loss is also reconstructed near the power takeoff electrodes though the voltage loss is smaller than that observed in the experimental result. The electric power output under the nonuniform inlet temperature condition is 40% smaller than that under the uniform inlet temperature condition. This is because the ratio of the Joule dissipation to the work by the Lorentz force increases owing to the decrease of active generator region as the current concentrates in the high-temperature region when the inlet temperature nonuniformity is considered. © 2013 Institute of Electrical Engineers of Japan. Published by John Wiley & Sons, Inc. [ABSTRACT FROM AUTHOR]

The article discusses the effects of electric arc behavior and electrode temperature on the current distribution and the location of arc spots in the boundary layer of magnetohydrodynamic generator. Based on numerical analysis, the potential distribution between electrodes drop dramatically across the boundary layer. If the wall temperature in the arc is high, the heat flux is concentrated on the laminar layer due to the presence of high effective thermal conductivity. The arc spots move in three-dimensional space.

The article discusses the operational characteristics of a power consolidation circuit for Faraday-type magnetohydrodynamic generator. The fundamental characteristics of Christmas tree type and Master/Slave type consolidation circuits are discussed, as well as the electrical nonuniformities caused by slag polarization. A schematic diagram of Christmas tree type power consolidation circuit with electrodes is presented.

The high-temperature ceramic electrode for an open-cycle MHD generator is now under intensive study but it can not be used in practice today. Presently available electrodes are of low-temperature type and made of copper. Currents of such low-temperature electrodes are carried in an arc discharge mode if natural gas or heavy oil is used as fuel. The current and voltage distributions around the electrodes often become very non- linear due to the effect of negative voltages current characteristics of the arc current.