Noise-suppressing jet engine nozzles and method

In a jet engine including a nozzle for a discharge gas flow of such engine, such nozzle including noise-suppressing mixing means for promoting rapid mixing of at least a portion of the discharge gas flow with ambient air, the improvement comprising the noise-suppressing mixing means including means for promoting substantially more rapid mixing of the upper portion of the discharge gas flow with ambient air than of the lower portion of the discharge gas flow with ambient air, the lower portion of the discharge end of the nozzle being arcuate for discharging the lower portion of the discharge gas flow without promoting rapid mixing of such lower portion with ambient air.

In a jet engine including a nozzle for a discharge gas flow of such engine, such nozzle including noise-suppressing mixing means for promoting rapid mixing of at least a portion of the discharge gas flow with ambient air, the improvement comprising the noise-suppressing mixing means including means for promoting substantially more rapid mixing of the upper portion of the discharge gas flow with ambient air than of the lower portion of the discharge gas flow with ambient air, such noise-suppressing mixing means including at least one lobe located in the upper portion of the discharge end portion of the nozzle.

In a jet engine including a nozzle for a discharge gas flow of such engine, such nozzle including noise-suppressing mixing means for promoting rapid mixing of at least a portion of the discharge gas flow with ambient air, the improvement comprising the noise-suppressing mixing means including means for promoting substantially more rapid mixing of the upper portion of the discharge gas flow with ambient air than of the lower portion of the discharge gas flow with ambient air, such noise-suppressing mixing means including a lower tube of large cross-sectional area for discharging the lower portion of the discharge gas flow and at least one upper tube disposed above said lower tube and of substantially smaller cross-sectional area than said lower tube.

In a jet engine including a nozzle for a discharge gas flow of such engine, such nozzle including noise-suppressing mixing means for promoting rapid mixing of at least a portion of the discharge gas flow with ambient air, the improvement comprising the noise-suppressing mixing means including means for promoting substantially more rapid mixing of the upper portion of the discharge gas flow with ambient air than of the lower portion of the discharge gas flow with ambient air, such noise-suppressing mixing means including deflectors disposed for promoting rapid mixing of the upper portion of the discharge gas flow with ambient air.

In a jet engine including a nozzle for a discharge gas flow of such engine, such nozzle including noise-suppressing mixing means for promoting rapid mixing of at least a portion of the discharge gas flow with ambient air, the improvement comprising the noise-suppressing mixing means including means for promoting substantially more rapid mixing of the upper portion of the discharge gas flow with ambient air than of the lower portion of the discharge gas flow with ambient air, such jet engine being a turbofan including means for producing a primary exhaust flow and means for producing a fan flow, the noise-suppressing mixing means including means for promoting rapid mixing of the upper portion of the primary exhaust flow with ambient air.

In a turbofan including a primary exhaust nozzle, means for producing a primary exhaust flow through such primary exhaust nozzle, a fan nozzle and means for producing a fan flow through such fan nozzle, the improvement comprising the turbofan including means for reducing noise perceived at a selected location, said noise-reducing means including means for thickening the fan flow at the side of the turbofan closest to the selected location and means for promoting mixing with ambient air of the portion of the primary exhaust flow at the side of the turbofan generally remote from the selected location.

In a jet engine including an exhaust nozzle having a substantially planar discharge end without any substantial fore-and-aft extending notch, means for producing an exhaust flow through such nozzle and noise-reducing mixing means for promoting rapid mixing of at least a portion of the exhaust flow with air surrounding the exhaust nozzle immediately downstream of such nozzle, the improvement comprising the mixing means including means for promoting rapid mixing of only the generally upper portion of the exhaust flow with air generally above the exhaust nozzle for reducing noise perceived below the jet engine without shifting the spectrum of such noise to include a substantially greater proportion of high frequency noise.

The method of reducing the noise perceived at a desired location speed from a jet engine including a discharge nozzle having a generally planar discharge end without any substantial turbulence-promoting fore-and-aft extending notch which comprises promoting substantially more rapid mixing of the portion of the discharge gas flow of such engine at its side generally remote from such desired location than at its side closer to such desired location.

In a jet engine including a nozzle for a discharge gas flow of such engine, such nozzle having a discharge end with a smooth continuous periphery without any substantial fore-and-aft extending notch and including noise-suppressing mixing means for promoting rapid mixing of at least a portion of the discharge gas flow with ambient air rearward of the nozzle discharge end, the improvement comprising the noise-suppressing mixing means including means for promoting rapid mixing of the upper one-half of the discharge gas flow with ambient air to a greater extent than mixing of the lower one-half of the discharge gas flow with ambient air.