<DOC>
<DOCNO>
401
</DOCNO>
<TITLE>
inviscid hypersonic airflows with coupled non-equilibrium
processes .
</TITLE>
<AUTHOR>
hall,j.g., eschenroeder,a.w. and marrone,p.v.
</AUTHOR>
<BIBLIO>
ias paper 62-67, 1962.
</BIBLIO>
<TEXT>
  analyses have been made of the effects of coupled chemical rate
processes in external inviscid hypersonic airflows at high enthalpy
levels .  exact (numerical) solutions have been obtained by the
inverse method for inviscid airflow over a near-spherical nose
under flight conditions where substantial nonequilibrium prevails
through the nose region .  typical conditions considered include
nose radii of the order of 1 ft at an altitude of 250,000 ft and
velocities of 15,000 and 23,000 ft per sec .
  the results illustrate the general importance of the coupling
among the reactions considered .  these included dissociationrecombination,
bimolecular-exchange, and ionization reactions .
the exact solutions show the bimolecular, no exchange reactions
to be important in blunt-nose flow for the kinetics of no and n,
as they are in the case of a plane shock wave .  an important
difference between blunt-nose flow and plane shock flow, however,
is the gasdynamic expansion in the curved shock layer of the
former .  this expansion reduces post-shock reaction rates .  as a
consequence, in the regime studied the oxygen and nitrogen-atom
concentrations tend to freeze in the nose region at levels below
those for infinite-rate equilibrium .  the reduction below the
equilibrium dissociation level can be large, particularly for
nitrogen dissociation at higher velocities .
  in the regime considered, the chemical kinetics are dominated
by two-body collision processes .  the inviscid nose flow, including
coupled nonequilibrium phenomena, is thus amenable to
binary scaling for a given velocity .  the binary scaling is demonstrated
for a range of altitude and scale by correlation of the
exact solutions for given velocity and a constant product of
ambient density and nose radius .  this similitude, which can
also scale viscous nonequilibrium and radiation phenomena in the
shock layer, provides a useful flexibility for hypersonic testing
where it is applicable .
  the afterbody inviscid-flow problem is briefly discussed in the
light of the results for the nose flow .
</TEXT>
</DOC>
