<DOC>
<DOCNO>
603
</DOCNO>
<TITLE>
the 7 in. x 7 in. hypersonic wind tunnel at r.a.e. farnborough
part ii. heater performance .
</TITLE>
<AUTHOR>
j. f. w. crane
</AUTHOR>
<BIBLIO>
</BIBLIO>
<TEXT>
tests on the storage heater, which is cylindrical in form and mounted
horizontally, show that its performance is adequate for operation
at m=6.8 and probably adequate for flows at m=8.2 with the existing
nozzles .  in its present state, the maximum design temperature of 680
degrees centigrade for operation at m=9 cannot be realised in the tunnel
because of heat loss to the outlet attachments of the heater and quickacting
valve which form, in effect, a large heat sink .  because of this
heat loss there is rather poor response of stagnation temperature
in the working section at the start of a run .  it is hoped to cure this
by preheating the heater outlet cone and the quick-acting valve .
at pressures greater than about 100 p.s.i.g. free convection through the
fibrous thermal insulation surrounding the heated core causes the top
of the heater shell to become somewhat hotter than the bottom, which
results in /hogging/ distortion of the shell .  this free convection
cools the heater core and a vertical temperature gradient is set up
across it after only a few minutes at high pressure .
modifications to be incorporated in the heater to improve its performance
are described .
</TEXT>
</DOC>
