|
The flow structure, induced noise and vibration of low Mach
number jets are experimentally investigated. It appears that the
SPL along the center line of the jet becomes the largest at x/
D=5, it then decays at further down-stream locations as the
velocity profile does. At M=0.2, the pressure distribution shows
that the jet is unstable azimuthally for x/D≦10. This phenomena
was not obvious at x/D=20. The energy spectra of the streamwise
velocity fluctuation demonstrate a broad band near x/D=5 and
from x/D=10 to 20. The jet induced noise has high frequency
content near the nozzle exit and decays downstream. The
vibration of a metal plane in a low Mach number jet is induced
by both large scale vortices of low frequencies and high
frequency turbulent flowat natural frequencies of the plane.
|