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 OFFICIAL USE ONLY
the temperature range, a moderate seeding with NaK (sodium-potassium)
mixture would be sufficient to produce an electrical conductivity from > 100
mho/m to as high as 1,000-3,000 mho/m. With this level of conductivity, very
modest magnetic field B~0.1-0.2 Tesla would suffice for a strong MHD
performance (Figure 10).
Modeling shows that MW-scale power can be generated in these conditions by a
surface-integrated MHD system from 1 square meter of vehicle surface.
Interestingly, calculations show that the additional weight of the system,
assuming a 1,000-second mission, is determined mostly by the water required to
cool the copper-wire electromagnet and that the additional weight is quite
acceptable, increasing the practicality of the system. 37, 38, 39, 40
a for virtual
lining and
crease
Figure 10. Reentry Vehicle With Surface-Integrated MHD Device and Plasma­
Enabled Virtual Streamlining and L/D Increase.
One good use of such hig h power would be to create a plasma in front of the
vehicle in order to reduce drag (Figure 10). Nonoptimized analysis shows that
the "return" (i.e., the drag power saved divided by the power spent on creating
the plasma) can easily be as high as 40-50 (i.e., the drag power saved is
40-50 times greater than the power spent on the plasma). 41 There are
theoretical and experimental indications that with proper shaping of the plasma
region (specifically, making it long and thin), the "return" can be > 100. Thus,
this "reverse energy bypass" would result in substantial reduction in drag and
increase in L/D (lift-to-drag ratio) by tens of percent. The increase in L/D would
directly translate in increased downrange for an unpowered hypersonic global
"glider" and in increased cross-range for a de-orbiting space asset. Note that off-
UNCLASSIFIEDfFQR &FFIEilslll ~91: 8Hl'I
21