Computational Simulations of Power Extraction in MHD Channel

A detailed computational analysis of the flow in, and power extraction from, a combustion-driven, MHD channel is described. The geometrical configuration considered is taken from a companion experiment involving a combustor discharging into a convergingdiverging nozzle that, in turn, feeds an MHD channel. A mixture of jet fuel and aluminum slurry was burned with gaseous oxygen to provide a high-temperature working fluid. Electrical conductivity was provided by seeding the propellants with potassium carbonate powder. The C-D nozzle was designed to deliver a nominally uniform Mach 2 flow to the MHD channel. The computations started from the burned gases at the entrance to the C-D nozzle, and included a full 3-D analysis of both fluids and electromagnetics. In the MHD power extraction tests, an external magnetic field is applied and the two ends of the Hall channel are connected electrically by means of a load resistor. The resulting MHD power generation is then measured experimentally and the detailed electromagnetic and fluid dynamic conditions are predicted computationally as a validation case for the combined fluids/electromagnetic simulation. Overall, the prediction appears to provide reasonable agreement with the measurements while simultaneously providing local details of both magnetic and fluid dynamic phenomena that are beyond the resolution capability of available instrumentation.