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National Advisory Committee for Aeronautics, Technical Notes - Investigation of Heat Transfer from a Stationary and Rotating Ellipsoidal Forebody of Fineness Ratio 3

In the general field of design of modern all-weather aircraft, the
problem of protecting bodies of revolution against icing has become of
increasing importance. Many aircraft components are essentially simple
bodies of revolution; examples of these are radomes, body noses, engine
accessory housings, and the large spinners of turboprop engines. The
design of thermal icing protection systems for theSe components requires
knowledge of the heat—transfer relations for both stationary and rotating
bodies of revolution. Such information is of interest also in the general
field of heat transfer. Several theoretical studies of the problem have
been made (refs. 1 and 2). However, very little-experimental heat—
transfer data for such bodies are available and the data_are generally of
limited scope.

Experimental investigations have been made at the NACA Lewis labora—
tory of the heat transfer from bodies of revolution in.order to Obtain
more extensive data than are presently available, including the effects
of angle of attack and rotation. The investigation was made as part of
a general study of icing and icing protection of bodies of revolution."
This report presents the results of an investigation of the_heat transfer
in clear air from the surface of an ellipsoidal forebody of fineness ratio
5 and a 20-inch maximum diameter. Similar results for a larger—diameter
ellipsoidal forebody of fineness ratio 2.5 are reported in reference 5.

In the present study the steady-stage convective heat transfer was de-
termined with and without rotation of the ellipsoidal forebody over a
range of airspeeds up to 240 knots, rotational speeds up to 1200 rpm, and
angles of attack of 0°, 5°, and 6°. Limited transient—heating data were _
also obtained. Heat was provided by an internal electric heater designed
and instrumented to yield as much basic heat-transfer data as possible'
while at the same time preserving the performance andijnstructional de-
tails of a representative practical heater installation.