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National Advisory Committee for Aeronautics, Report - Test of a Single Stage Axial Flow Fan

A single-stage axial fan was built and tested in the
shop of the propeller-research tunnel of the NAC'A. The
fan comprised a single 24-blade rotor having a diameter
of .91 inches and a solidity of 0.86 and a set of 3? con-
travenes hazing a solidity of 1.33. The rotor was driven
by a zit-horsepower motor capable of rotating at a speed
of 3600 rpm. The fan was tested for volume, pressure,
and eficiency over a range of delivery pressures and
volumes for a wide range of contravene and blade-angle
settings.

The test results are presented in chart form in terms of
nondimensional units in order that similar fans may be
accurately designed with a minim-um of efort. The mari-
mu—m eficiency (88 percent) was obtained by the fan at a
blade angle of 80° and a contravane angle of 70". An
eficieney of 80 percent was obtained by the fan with the
contravenes removed.

In connection with tests of airplane cooling systems
that are being conducted in the propeller-research tun-
nel of the National Advisory Committee for Aeronau—
ties, the need was felt for information on axial-fan
design inasmuch as the indications are that such fans
will be used in airplane cooling systems in the immediate
future. In designs of aircraft with submerged engines,
it may become necessary to provide a fan that will
furnish the necessary volume of air to cool the engines,
the oil coolers, and the intercoolers. In pusher-propel-
ler radial-engine installations, the use of ‘an axial fan
may help to solve an otherwise difficult cooling prob-
lem. The decision was therefore made to build an
axial-flow fan with adjustable blades and contravenes
and to conduct a series of performance tests on it.

pressure and eficiency curves. This error was due to
rotation of the air inside the space downstream of the
fan hub and affected the reading of the pressure 17,. A
slight alterationto the test set-up corrected this source,
of error. The tests were then repeated and the cor-
rected data are inserted in this report.