• Version
• 168 Downloads
• 2.48 MB File Size
• 1 File Count
• January 31, 2017 Create Date
• January 31, 2017 Last Updated

National Advisory Committee for Aeronautics, Technical Notes - Experimental Droplet Impingement on Four Bodies of Revolution

The rate and area of cloud droplet impingement on four bodies of
revolution were Obtained experimentally in the NAGA.Lewis icing tunnel
with a dye-tracer technique. The study included spheres, ellipsoidal
forebodies of fineness ratios of 2.5 and 5.0, and a conical forebody of
50° included angle and covered a range of angles of attack from 0° to 6°
and rotational speeds up to 1200 rpm. The data were obtained at an air-
speed of 157 knots and are correlated by dimensionless impingement
parameters.

In general, the experimental data show that the local and total
impingement rates and impingement limits of bodies of revolution are pri-
marily functions of the modified inertia parameters, the body shape, and
fineness ratio. Both the local impingement rate and impingement limits
depend upon the angle of attack. Rotation of the bodies had a negligible
effect on the impingement characteristics except for an averaging effect
at angle of attack. For comparable diameters the bluffer bodies had the
largest total impingement efficiency, but the finer and sharper bodies
had the largest values of maximum local impingement efficiency and, in
most cases, the largest limits of impingement. In most cases, the impinge—
ment characteristics were less than those calculated from theoretical
trajectories; in general, however, fairly good agreement was obtained be-
tween the experimental and theoretical impingement characteristics.

The design and evaluation of icing protection equipment for aircraft
components require a knowledge of the local and total rates of cloud drop-
let impingement and the surface extent of draplet impingement. These
impingement characteristics are important in determining the extent of a
surface requiring icing protection, the local and total protection require-
ments, the shape, size, and location of ice formations on aircraft com-
ponents, and the aerodynamic penalties associated with icing of aircraft
surfaces.