Dry Cooled Jet Aircraft Runup Noise Suppression System.
DEPARTMENT OF THE NAVY WASHINGTON D C
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A stationary jet exhaust noise suppressor has an elongate housing containing a longitudinal tunnel. The hot exhaust from a jet engine blows through the tunnel and is deflected upwards at the tunnels end. A number of resonant chambers are located along the tunnels length and have resonant frequencies corresponding to objectional frequencies in the jet exhaust noise spectrum. Since there are a number of perforations in the walls of the tunnel, the resonant chambers are put in communication with the jet exhaust noise in the tunnel to attenuate the objectionable frequencies. Since the resonant chambers are formed by rigid stainless steel panels, trouble free, long term noise suppression is assured. A cooling duct is provided in the walls of the housing to draw in ambient air to reduce the possibility of heat damage. Author