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National Advisory Committee for Aeronautics, Technical Notes - The Effects of Aerodynamic Heating on Ice Formations on Airplane Propellers

An investigation has been. made of the effect of aero—
dynamic heating on propeller-blade temperatures and its
relation to propeller icing. The blade temperature rise
resulting from aerodynamic heating was measured and the
relation between the resulting blade temperatures and the
outer limit of the iced-over region was examined. The
test results have indicated that the outermost station at
which ice formed on a propeller blade was determined by
the blade temperature rise resulting from the aerddynamic
heating at that point. An empirical analytical relation
betWeen-the blade-element velocity and the air tempera-.
ture at.which ice would form was established by the data.

The problem of ice prevention on airplane propellers
has created an interest in the temperature rise of the '
propeller blade due to aerodynamic'heating. The heating
effect of the flow of air over ampropeller is of particu-
lar interest in the study of the application of thermal
means of ice prevention.

Aerodynamic.heating reenlts from adiabatic compres-
sion of the air at the region of stagnation pressure and
from friction in the regions of viscous flow. According
to reference 11 the temperature rise at the leading edge
is slightly greater than that over the rear portion of
the airfoil, the difference depending on the shape of the
airfoil and the. angle of attack. According to t ests at
present unreported, the temperature rise over the rear
part of an airfoil due to aerodynamic heati-ng is within
about 85 percent of that at the leading edge.

Although only the temperature rise of the air at the
leading edge can be precisely expressed by the adiabatic
equation. an approximation for the entire airfoil section
can be made that will be satisfactorily accurate for the
intended application of this expression.