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This Defense Intelligence Reference Document from the Defense Intelligence Agency, dated 21 November 2010, was produced in FY 2010 under the Advanced Aerospace Weapons System Applications (AAWSA) Program. It reviews propulsion concepts that use plasmas and magnetohydrodynamics. It finds the Ajax MHD energy bypass concept meaningless below Mach 12 but calls a reverse energy bypass with a Virtual Cowl potentially practical. It also predicts that electric propulsion will become standard for spacecraft.
UNCLASSIFIED//F8A 8FFH11Ck Yli'li ODIi X --------= MHD heat-into-power conversion Figure 8. The Reverse Energy Bypass Concept. The red arrow symbolically depicts the general direction of energy bypass - upstream. A promising version of the reverse energy bypass concept uses the electric power extracted from the flow in the MHD generator to increase the air mass flow rate through the combustor in off-design conditions. If the inlet is designed for shock-on-lip condition at a certain high Mach number (e.g., Mach 8), then at Mach numbers lower than the design value (e.g., Mach 6) the inlet does not completely capture the compressed flow, which is associated with the so-called spillage drag, effectively reducing the thrust. This undesirable effect can be prevented by the so-called virtual cowl-a heated region upstream of the cowl lip (Figure 9). 33 , 34 This heated (e.g., plasma) region deflects the flow and helps with scooping more air into the inlet. Moreover, with proper positioning, only cold (unheated) air is scooped into the inlet, thus avoiding reduction in total pressure and thrust that would have occurred if heated air were scooped into the propulsion system. 19 UNCLASSIFIED/FOR 8FFllll'IIL ~9!! enc I
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Report, from the dia collection. The PDF is mirrored here; the original link is above. 32 pages are in the text index: search them above, or from the library's search.