AAWSAP DIRD, MHD Air Breathing Propulsion and Power for Aerospace Applications, November 2010

Text

This text came with the file. It may have mistakes. When the text and the image disagree, the image is right.

UNCLASSIFIED//FOR 055iliCl.t.k WSE 8HL'f
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 hig h 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.
UNCLASSIFIED/FQA QFFHiilif.tl: WSE 8HL'I
19