Cascade plug nozzle
AssigneeThe United States of America as represented by the United States National Aeronautics and Space Administration Office of General Counsel-Code GP
InventorBlake W. Corson, Jr.
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Abstract
An exhaust nozzle for a jet aircraft provides jet noise suppression. The nozzle includes a plurality of coaxial airfoil ring segments which are spaced serially along the longitudinal axis of the nozzle to define a plurality of annular coaxial channels therebetween. The diameters of the segments progressively decrease downstream along this axis and the exits of the channels are non-coplanar. The radial depths of the channels are small as compared with the axial distance between adjacent channel exits so that noise is emitted non-simultaneously from the channel exits as a series of weakened pulses staggered in time. The boattail angles of the outer surfaces of the ring airfoil segments increase in magnitude with increasing distance downstream to reduce drag.
Claims10
A low drag exhaust nozzle for a jet aircraft which provides jet noise suppression comprising a plurality of coaxial annular segment means for sequencing the exit of exhaust gas sound wave pressure perturbations, enveloping the majority of exhaust gases in a thin exhaust gas jet layer, and converting the kinetic energy of the exhaust jet into a forward, drag-reducing thrust component, wherein said coaxial annular segments are spaced serially along the longitudinal axis of the nozzle, the diameters of said annular segments progressively decreasing downstream along said axis so that each segment is smaller in diameter than the preceding upstream segment and is larger in diameter than the subsequent downstream segment, each of said annular segments overlapping both the preceding upstream annular segment and the subsequent downstream annular segment for overlapping lengths which are small compared to the axial length of said annular segments, and said overlapping lengths defining a plurality of coaxial channels therebetween having noncoplanar exits, the length of each of said channels being small compared with the axial length of said annular segments defining said channels and the radial depth of at least the first, most upstream channel being small compared with the axial distance between the exits of said first channel and the next downstream channel and the boattail angle between the external surface of the most upstream annular segment and the longitudinal axis of the nozzle is less than 10.degree..
An exhaust nozzle for a jet aircraft which provides jet noise suppression comprising a plurality of coaxial annular segments spaced serially along the longitudinal axis of the nozzle, the diameters of said annular segments progressively decreasing downstream along said axis so that each segment is smaller in diameter than the preceding upstream segment and is larger in diameter than the subsequent downstream segment, each of said annular segments overlapping both the preceding upstream annular segment and the subsequent downstream annular segment for overlapping lengths which are small compared to the axial length of said annular segments, and said overlapping lengths defining a plurality of coaxial channels therebetween having noncoplanar exits, the length of each of said channels being small compared with the axial length of said annular segments defining said channels and the radial depth of at least the first, most upstream channel being small compared with the axial distance between the exits of said first channel and the next downstream channel, wherein the boattail angles of the outer surfaces of the annular segments increase in magnitude progressively with downstream distance.
An exhaust nozzle for a jet aircraft which provides jet noise suppression comprising a plurality of coaxial annular segments spaced serially along the longitudinal axis of the nozzle, the diameters of said annular segments progressively decreasing downstream along said axis so that each segment is smaller in diameter than the preceding upstream segment and is larger in diameter than the subsequent downstream segment, each of said annular segments overlapping both the preceding upstream annular segment and the subsequent downstream annular segment for overlapping lengths which are small compared to the axial length of said annular segments, and said overlapping lengths defining a plurality of coaxial channels therebetween having noncoplanar exits, the length of each of said channels being small compared with the axial length of said annular segments defining said channels and the radial depth of at least the first, most upstream channel being small compared with the axial distance between the exits of said first channel and the next downstream channel, and further comprising an upstream lip segment located upstream of the most upstream annular segment and a terminating plug segment located downstream of the most downstream annular segment.
Dependencies are inferred from the claim text.