<DOC>
<DOCNO>
628
</DOCNO>
<TITLE>
thermal effects on a transpiration cooled hemisphere .
</TITLE>
<AUTHOR>
gollnick,a.f.
</AUTHOR>
<BIBLIO>
j. ae. scs. 29, 1962, 583.
</BIBLIO>
<TEXT>
  an approximate method is used to obtain the injection
distribution which would exist on an isothermal,
transpiration-cooled hemisphere in a supersonic stream .
this distribution is the same for both air and helium
injection, and is independent of the blowing level .  a
model having this distribution was tested in the naval
supersonic laboratory wind tunnel at a mach number
of 3.53 .  it is concluded that the design technique is
reasonably accurate .  data taken near the nose are
compared with the theories for air and helium injection
.  the agreement in the case of the reduction in
heat-transfer coefficient is good .  the values of insulated
wall temperature obtained near the nose with
helium injection are 8 percent above the local stagnation
temperature, and largely independent of injection
rate .  it is believed that this phenomenon may be
attributed to the thermal diffusion of the helium within
the boundary layer .  air injection causes a slight reduction
in the insulated wall temperature .  it is shown
that injection of either air or helium at the hemisphere
nose considerably reduces the heat flux at the surface .
the additional reduction in heat flux resulting from
helium injection as opposed to air injection, and predicted
by existing theory, is largely absent .
</TEXT>
</DOC>
