Abstract:
The deficiency in the clear understanding of the turbulent jet structure. despite
its important speculative role. provided the motivation for the present study.
Somecharacteristics of circular jet with and without excitation were investigated
along with the calculation of some integral and differential variables. Constant
temperature hot wire anemometer responses and First Fourier Transform (FFT)
analyzer traces have been analyzed in order to get an articulate picture of the
jet response to pure. tone acoustic excitation. The effect of jet column mode and
shear layer mode excitation are also considered in this research. The results
show that the longitudinal turbulence intensities in the centerline and different
axial distances parallel to the centerline can both be enhanced and suppressed
by inducing different conditions of excitation.
The centerline turbulence intensities started to be enhanced at lower excitation
frequency and after reaching the maximum started to decrease with further
increase in excitation frequencies. However on a line parallel and half diameter
apart from centerline. suppression is observed for all excitation frequencies. Both
in enhancement and suppression of turbulence the effect of jet column mode
excitation is nearly stable while that of shear layer mode excitation is unstable.
