Abstract
A fuel-cell-powered magnetoplasma jet engine (magjet) using electron-beam ionizers is here proposed for air-breathing flight in the supersonic/hypersonic regime. The engine consists of a fuel-cell duct containing the power source and of a high-speed duct producing most of the thrust through a magnetoplasmadynamic (MPD) accelerator. To reduce the shocks and heat loads in the fuel cells, the enthalpy of the air is extracted beforehand through a MPD generator. The power produced by the latter and by the fuel cells is then split optimally between the MPD accelerator located in the high-speed duct and one located downstream of the fuel cells. The performance is assessed through exact solutions of a quasi-one-dimensional model, which includes the effect of ion slip, Joule heating, and heat dissipated through electron-beam ionization. The magnetic Held strength as well as the mass-flow-rate ratio between the high-speed and fuel-cell ducts are seen to affect the thrust considerably at lower Mach number, but to have a smaller impact at hypervelocities. Flight beyond Mach 6 would necessitate substantial cooling of the fuel cells caused by the ion slip effect preventing sufficient enthalpy extraction, independently of the magnetic field strength. For a fuel-cell efficiency of 0.6 and a mass-flow-rate ratio of 5, the magjet delivers a specific impulse within 15% of the one of the turbojet in the Mach number range 1-3 given a magnetic field of 8 T. From Mach 3 to 5, a magnetic field strength varying between 2 and 4 T is seen to be sufficient to match the performance of conventional engines.
Original language | English (US) |
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Pages (from-to) | 433-441 |
Number of pages | 9 |
Journal | Journal of Propulsion and Power |
Volume | 21 |
Issue number | 3 |
DOIs | |
State | Published - 2005 |
Externally published | Yes |
ASJC Scopus subject areas
- Aerospace Engineering
- Fuel Technology
- Mechanical Engineering
- Space and Planetary Science