Abstract: A noise suppressor (24, 76) for a jet engine nozzle (12, 64) is constructed so that the noise suppressor internally ventilates the nozzle jet efflux with ambient air by tubes (26, 78) having ambient inlets (30, 90) upstream of the nozzle discharge end (38, 72). The noise suppressor tubes may be relatively short with respect to the nozzle length but extend downstream of the nozzle so that the gas exhaust jet pumps or aspirates ambient air through the internally ventilating tubes so as to properly mix the air with the gas exhaust to suppress the noise from the jet engine exhaust. The internally ventilating ducts of the noise suppressor extend downstream of the nozzle (38, 40, 72, 84) at least to just beyond a region of high static pressure in the jet and extend in the jet to where a substantial ejected airflow pressure and volume are maintained in the ducts. Where the internally ventilating ducts are arranged concentrically about the axis of the discharged jet, noise is suppressed radially around the nozzle.

Abstract: Noise perceived below a turbofan is reduced by providing a thicker fan flow below the turbofan primary exhaust flow than is present in conventional turbofans having generally circular and concentric fan and exhaust flows. To thicken the fan flow, the exhaust nozzle is offset upward in the fan nozzle, or the exhaust nozzle discharge end is canted to offset the exhaust flow upward, or the exhaust nozzle is flattened to a generally rectangular or an elliptical shape having a major horizontal axis. In any of these cases, the thickness of the fan flow below the primary exhaust flow is increased and less noise is perceived below the turbofan than if circular concentric fan and exhaust flows were produced. In one embodiment a noise-suppressing thickened fan flow is used in combination with a conventional noise-suppressing multilobe or multitube mixing nozzle to further reduce noise perceived below the turbofan.

Abstract: Each duct of a plurality of generally cylindrical exhaust ducts disposed in approximately uniform annular arrangement about an axis is a tube, or a lobe of a radially-branched passage, having a discharge end canted so that the radially outer portion of such duct end projects rearward farther than any other portion of the duct end. The canted duct ends direct the major portion of the exhaust of a jet engine inward toward the axis of the annular exhaust duct arrangement in a plurality of exhaust jets, effecting a rearwardly convergent relationship of the jets.

Abstract: Multiported and multinozzled sectors are pivotally mounted to swing between positions cooperatively spanning a jet engine exhaust duct and retracted positions alongside the wall of such duct. Such sectors are located between a forward nozzle section and a rearward nozzle section deformable to alter the contour of the passage through the exhaust duct. Such nozzle sections and noise suppressor sectors are located rearwardly of a thrust reverser. Each nozzle is of elongated cross section, preferably being elliptical, and arranged so that the greater dimension or major axis extends substantially radially of the noise suppressor sector. The nozzles are dimensioned, proportioned and arranged to provide adequate flow through them and to afford space between the nozzles to facilitate flow of ventilating air to mix equally with the exhaust gas flowing through all the nozzles at least in the central portion of the noise suppressor.