Disclosed is a means for reducing jet engine exhaust noise wherein mixing
is enhanced between adjacent exhaust flows and between exhaust flow and
free-stream flow. Also disclosed is a means for improving the thrust of
jet engines and for reducing the noise and drag of aircraft. The device
is a segmented, triangular or trapezoidal shaped, curved extension to a
nozzle's sleeve or surface trailing edge that results in a serrated
trailing edge. The extensions enhance the natural free mixing of the
adjacent flows and therefore reduce the acoustic energy associated with
the velocity differences between the streams in which they are imbedded.
The novel structure forces adjacent flows to penetrate into one another
to a greater depth than that achieved with free mixing and results in a
more uniform flow in a shorter stream wise distance. As a result of the
enhanced mixing, drag on flow surfaces that are downstream of the devices
and are scrubbed by the flows adjacent to the devices can be reduced.