<DOC>
<DOCNO>
193
</DOCNO>
<TITLE>
a study of inviscid flow about air foils at high supersonic
speeds .
</TITLE>
<AUTHOR>
eggers, a.j., syvertson, c.a., and krqus, s.
</AUTHOR>
<BIBLIO>
naca report 1123
</BIBLIO>
<TEXT>
steady flow about curved airfoils at high supersonic speeds is
investigated analyticially . with the assumption that air behaves
as a diatomic gas, it is found the the shock-expansion
method may be used to predict the flow about curved airfoils up to
extremely high mach numbers, provided the flow deflection
angles are not too close to those corresponding to shock detachment
. this result applies not only to the determination of the
surface pressure distribution, but also to the determination of the
whole flow field about an airfoil . verification of this observation
is obtained with the aid of the method of characteristics by
extensive calculations of the pressure gradient and shock-wave
curvature at the leading edge, and by calculations of the pressure
distribution on a 10-percent-thick biconvex airfoil at 0 angle of
attack .
an approximation to the shock-expansion method for thin
airfoils at high mach numbers is also investigated and is found
to yield pressures in error by less than 10 percent at mach
numbers above three and flow deflection angles up to 25 . this
slender-airfoil method is relatively simple in form and thus may
prove useful for some engineering purposes .
effects of caloric imperfections of air manifest in disturbed
flow fields at  high mach numbers are investigated, particular
attention being given to the reduction of the ratio of specific
heats . so long as this ratio does not decrease appreciably below
to include the effects of these imperfections, should be substantially
as accurate as for ideal-gas flows . this observation is verfied
with the aid of a generalized shock-expansion method and a
generalized method of characteristics employed in forms applicable
for local air temperatures up to about 5000 rankine .
the slender-airfoil method is modified to employ an average
value of the ratio of specific heats for a particular flow field .
this simplified method has essentially the same accuracy for
imperfect-gas flows as its counterpart has for ideal-gas flows .
an approximate flow analysis is made at extremely high mach
numbers where it is indicated that the ratio of specific heats may
approach close to 1 . in this case, it is found that the shock-expansion
method may be in considerable error,. however, the
busemann method for the limit of infinite free-stream mach
number and specific-heat ratio of 1 appears to apply with
reasonable accuracy .
</TEXT>
</DOC>
