Pulse Detonation Magnetohydrodynamic Power

Abstract

A series of laboratory-scale experiments were conducted to investigate the basic engineering performance characteristics of a pulse detonation-driven magnetohydrodynamic electric power generator. In these experiments, stoichiometric oxy-acetylene mixtures seeded with a cesium ‐hydroxide/methanol spray were detonated at atmospheric pressure in a 1-m-long tube having an i.d. of 2.54 cm. Experiments with a plasma diagnostic channel attached to the end of the tube cone rmed the attainment of detonation conditions (p2/p1 » 34 and D» 2400 m/s) and enabled the measurement of current density (» 2 A/cm 2) and electrical conductivity (» 6 mho/m) behind the detonation wave front. In a second set of experiments, a 30-cm-long continuous electrode Faraday channel, having a height of 2.54 cm and a width of 2.0 cm, was attached to the end of the tube using an area transition duct. The Faraday channel was placed inside a permanent magnet assembly having a nominal magnetic induction of 0.6 T, and the electrodes were connected to an active loading circuit to characterize power-extraction dependence on load impedance while also simulating higher effective magnetic induction. The experiments indicated peak power extraction at a load impedance between 5 and 10 X . The measured peak electrical energy density ranged from 10 to 10 3 J/m 3 when the effective magnetic induction was varied from 0.6 to 4.2 T. These results were in reasonable agreement with a simple electrodynamic model incorporating a correction for near-electrode potential losses. By scaling-up to a practical-size device, limiting the near-electrode potential drop to 10% of the induced potential, and optimizing seed-atomization characteristics, we anticipate a e ve- to tenfold increase in attainable electrical energy density.