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National Advisory Committee for Aeronautics, Technical Notes - General Correlation of Temperature Profiles Downstream of a Heated Air Jet Directed at Various Angles to Air Stream

An experimental investigation was conducted to determine the tem-
perature profiles downstream.of heated air jets directed at angles of
900 , 60o , 45° , and 500 to an air stream. The profiles were determined
at two positions downstream of the jet as a function of jet diameter,
jet density, jet velocity, free—stream density, free—stream velocity,
jet total temperature, orifice flow coefficient, and jet angle. A
method is presented which yields a good approximation of the tempera-
ture profile in terms of the flow and geometric conditions.

The discharging of heated high-velocity jets of air or vapor into
an air stream is employed in many installations either as a means of
heating the air stream or as a method of disposing of hot discharge
gases. For practical application, however, the discharging of heated
jets into an air stream requires knowledge of the temperature profiles
downstream of the heated jet and of the depth of penetration of the jet
into the air stream.

Heating an air stream by means of heated air jets directed perpen—
dicularly to the air stream has been previously reported in refer-
ences l and 2. A method is presented in reference 1 by which the tem—
perature profile and the depth of penetration of a circular heated air
jet directed perpendicularly to the air stream may be predicted at any
point downstream of the jet.

Because many installations employ jets which are directed at an
angle other than 900 to the air stream,-a study of the temperature pro—
files downstream of circular heated air jets directed at various angles
to the air stream.was conducted in the 2- by 20-inch tunnel at the NACA
Lewis laboratory. Sixteen heated air jets were investigated for a range
of free—stream velocities, jet total temperatures, jet total pressures,
and jet angles. The 16 jets investigated comprised a group of basic
jets with four diameters and each diameter was investigated for four
jet angles.