<DOC>
<DOCNO>
773
</DOCNO>
<TITLE>
q . app . math . 7, 1950, 381 . experiments on porous-wall
cooling and flow separation control in a supersonic
nozzle .
</TITLE>
<AUTHOR>
green,l. and nall,k.l.
</AUTHOR>
<BIBLIO>
j. ae. scs. 1959, 689.
</BIBLIO>
<TEXT>
  control of flow separation by fluid injection at one diverging
boundary of a two-dimensional, transparent-walled de laval
nozzle was investigated by spark schlieren photography of dry
nitrogen flows expanded from two stagnation temperatures
injection conditions at the permeable boundary were varied by
the use of three grades of porous stainless steel with nominal pore
diameters of 10, 20, and 30 microns, through which nitrogen was
forced by coolant reservoir pressures of 25, 50, and 100 psig, in
addition to the case of no forced injection .  pressure distribution
measurements were made along the nonpermeable diverging
boundary .  it was found that flow separation at expansion ratios
approaching the optimum value for maximum thrust coefficient
could be induced at the porous wall by a local injection mass
velocity of the order of a few per cent of the local main-stream
mass velocity .  separation at the solid boundary was not
noticeably influenced by injection at the opposite wall, and the
asymmetrical separation thus effected jet deflections of up to 10
degrees at the lower stagnation-pressure levels .  variation of the
wall heat-transfer condition by changing the stagnation temperature
did not significantly influence separation behavior .  temperature
measurements at the reservoir face of the porous section,
together with use of published correlations and of the rubesin
analysis for estimation of stream-side stanton numbers under
noninjection and injection conditions, respectively, permitted
heat-transfer calculations which indicated that the effectiveness
of the transpiration technique in controlling nozzle wall temperatures
derives primarily from intimate fluid-solid contact in a
porous material of high specific surface .
</TEXT>
</DOC>
