<DOC>
<DOCNO>
201
</DOCNO>
<TITLE>
supersonic flow past oscillating airfoils including
nonlinear thickness effects .
</TITLE>
<AUTHOR>
van dyke,m.d.
</AUTHOR>
<BIBLIO>
naca r1183, 1954.
</BIBLIO>
<TEXT>
  a solution to second order in thickness is derived for harmonically
oscillating two-dimensional airfoils in supersonic
flow .  for slow oscillations of an arbitrary profile, the result is
found as a series including the third power of frequency .  for
arbitrary frequencies, the method of solution for any specific
profile is indicated, and the explicit solution derived for a single
wedge .
  nonlinear thickness effects are found generally to reduce the
torsional damping, and so to enlarge the range of mach numbers
within which torsional instability is possible .  this destabilizing
effect varies only slightly with frequency in the range involved
in dynamic stability analysis, but may reverse to a
stabilizing effect at high flutter frequencies .  comparison with
a previous solution exact in thickness suggests that nonlinear
effects of higher than second order are practically negligible .
  the analysis utilizes a smoothing technique that replaces
the actural problem by one involving no kinked streamlines .
this stratagem eliminates all consideration of shock waves
from the analysis, yet yields the correct solution for problems
that actually contain shock waves .
</TEXT>
</DOC>
