<DOC>
<DOCNO>
101
</DOCNO>
<TITLE>
laminar heat transfer over blunt-nosed bodies at hypersonic flight
speeds .
</TITLE>
<AUTHOR>
lester lees
</AUTHOR>
<BIBLIO>
the ramo-wooldridge corporation, los angles, and california institute
of technology, pasadena, california
</BIBLIO>
<TEXT>
this paper deals with two limiting cases of laminar heat transfer over
blunt-nosed bodies at hypersonic flight speeds, or high stagnation temperatures..
 (a) thermodynamic equilibrium, in which the chemical reaction
rates are regarded as /very fast/ compared to the rates of diffusion
across streamlines., (b) diffusion as rate-governing, in which the volume
recombination rates within the boundary layer are /very slow/ compared
to diffusion across streamlines .  in either case the gas density
near the surface of a blunt-nosed body is much higher than the density
just outside the boundary layer, and the velocity and stagnation enthalpy
profiles are much less sensitive to pressure gradient than in the
more familiar case of moderate temperature differences .  in fact, in
case (a), the nondimensionalized enthalpy gradient at the surface is
represented very accurately by the /classical/ zero pressure gradient
value, and the surface heat-transfer rate distribution is obtained directly
in terms of the surface pressure distribution .  in order to
illustrate the method, this solution is applied to the special cases
of an unyawed hemisphere and an unyawed, blunt cone capped by a spherical
segment .
in the opposite limiting case where diffusion is rate-controlling the
diffusion equation for each species is reduced to the same form as the
low-speed energy equation, except that the prandtl number is replaced
by the schmidt number .  the simplifications introduced in case (a) are
also applicable here, and the expression for surface heat transfer rate
is similar., the maximum value of the ratio between the rate of heat
transfer by diffusion alone and by heat conduction alone in the case of
thermodynamic equilibrium is given by..  (prandtl no./schmidt no .)
when the diffusion coefficient is estimated by taking a reasonable value
of atom-molecule collision cross section this ratio is 1.30 .  additional
theoretical and (especially) experimental studies are clearly required
before these simple results are accepted .
</TEXT>
</DOC>
