A unified aeroacoustic jet noise prediction method has been developed based on the modeling of principal noise generation and emission mechanisms from first principles. It is demonstrated herein that this jet noise prediction method is a useful diagnostic tool for assessing the relative importance of the various mechanisms for a given nozzle type. The relative contributions of 1) turbulent mixing noise suppression, 2) shock-cell broadband noise suppression, 3) convective amplification suppression, and 4) fluid shielding attenuation have been evaluated for a high element number multichute suppressor to arrive at a plausible explanation for how multielement suppressors suppress jet noise. This explanation, an alternative view to historical conceptions of jet noise suppression, suggests an approach to designing low noise suppressor nozzles.
[1]
Michael Fisher,et al.
The characteristics of the turbulence in the mixing region of a round jet
,
1963,
Journal of Fluid Mechanics.
[2]
P. Gliebe,et al.
Aeroacoustics of Axisymmetric Single- and Dual-Flow Exhaust Nozzles
,
1978
.
[3]
H. Reichardt,et al.
On a New Theory of free Turbulence
,
1943,
The Journal of the Royal Aeronautical Society.
[4]
L. G. Alexander,et al.
Transport of momentum, mass, and heat in turbulent jets
,
1953
.
[5]
T. Balsa,et al.
The far field of high frequency convected singularities in sheared flows, with an application to jet-noise prediction
,
1976,
Journal of Fluid Mechanics.
[6]
Philip R. Gliebe,et al.
Aerodynamics and Noise of Coaxial Jets
,
1977
.