초록 ▼

A segmented exhaust nozzle for attenuating noise from a jet engine without adversely impacting the operability or operability limit related performance of the engine. The exhaust nozzle includes spaced apart fan nozzle inner and outer walls which form an annular exhaust gas flow path therebetween. T

A segmented exhaust nozzle for attenuating noise from a jet engine without adversely impacting the operability or operability limit related performance of the engine. The exhaust nozzle includes spaced apart fan nozzle inner and outer walls which form an annular exhaust gas flow path therebetween. The fan nozzle outer wall is segmented at the downstream end. The outer wall curves inwardly towards the inner wall and then turns back away from the inner wall to form an arcuate protrusion that extends into the exhaust gas flow path forming an aerodynamic throat. Through the segmented portion of the nozzle, the outer wall then continues to curve away from the inner wall before again curving back towards the inner wall at a nozzle exit station. The nozzle exit effective area is approximately equal in cross sectional area to a conventional exhaust nozzle exit area. The inwardly curving and then segmented outwardly curving portion of the exhaust nozzle forms a geometric influction that serves to reduce noise without negatively affecting engine operability or operability limit related performance.

대표청구항 ▼

A segmented exhaust nozzle for attenuating noise from a jet engine without adversely impacting the operability or operability limit related performance of the engine. The exhaust nozzle includes spaced apart fan nozzle inner and outer walls which form an annular exhaust gas flow path therebetween. T

A segmented exhaust nozzle for attenuating noise from a jet engine without adversely impacting the operability or operability limit related performance of the engine. The exhaust nozzle includes spaced apart fan nozzle inner and outer walls which form an annular exhaust gas flow path therebetween. The fan nozzle outer wall is segmented at the downstream end. The outer wall curves inwardly towards the inner wall and then turns back away from the inner wall to form an arcuate protrusion that extends into the exhaust gas flow path forming an aerodynamic throat. Through the segmented portion of the nozzle, the outer wall then continues to curve away from the inner wall before again curving back towards the inner wall at a nozzle exit station. The nozzle exit effective area is approximately equal in cross sectional area to a conventional exhaust nozzle exit area. The inwardly curving and then segmented outwardly curving portion of the exhaust nozzle forms a geometric influction that serves to reduce noise without negatively affecting engine operability or operability limit related performance. ing an error with respect to a particular one of the macroblocks and all of the encoder reference buffers having errors associated therewith, the encoder transmitting at least one macroblock that is encoded independent of any other macroblocks. 3. A method, according to claim 1, further comprising: in response to the decoder indicating an error with respect to a particular one of the macroblocks, the encoder and the decoder indicating a reference buffer associated with the macroblock is in error; and in response to all of the reference buffers of the decoder having errors associated therewith, the decoder transmitting a request to the encoder to transmit at least one macroblock that is encoded independent of any other macroblocks. 4. A method, according to claim 3, wherein in response to the request, the encoder transmits at least one macroblock that is encoded independent of any other macroblocks. 5. A method, according to claim 1, wherein the encoder using a second one of the reference buffers for error recovery includes: coding a macroblock using a second one of the reference buffers as a reference; and marking the selected one of the reference buffers as having an error. 6. A method, according to claim 5, further comprising: in response to marking the selected one of the reference buffers as having an error, the encoder setting a timer to indicate an amount of time since the error occurred; and in response to the amount of time since the error occurred being greater than a predetermined threshold, the encoder clearing the error associated with the selected one of the reference buffers. 7. A method, according to claim 6, wherein the predetermined threshold corresponds to a round trip transmission and processing time between the encoder and the decoder. 8. A method, according to claim 1, wherein the number of reference buffers used is increased in response to errors requiring the encoder to transmit at least one macroblock that is encoded independent of any other macroblocks and decreased if, after a predetermined amount of time, no errors requiring the encoder to transmit at least one macroblock that is encoded independent of any other macroblocks occur. 9. A method, according to claim 1, further comprising: associating each macroblock with a temporal reference number; and providing a table that maps each temporal reference number with one of: a particular one of the reference buffers and a value indicating that a macroblock corresponding to a temporal reference number is not being stored. 10. A method of transmitting video data between an encoder and a decoder, comprising: the encoder storing macroblocks in a plurality of reference buffers; the encoder transmitting macroblocks that are encoded relative to a selected one of the reference buffers; in response to an error with respect to a macroblock corresponding to the selected one of the reference buffers, the encoder using a second one of the reference buffers for error recovery if there is no error associated with the second buffer. 11. A method, according to claim 10, further comprising: in response to an error with respect to a macroblock and all of the reference buffers having errors associated therewith, the encoder transmitting at least one macroblock that is encoded independent of any other macroblocks. 12. A method, according to claim 10, wherein in response to a receiving a request, the encoder transmits at least one macroblock that is encoded independent of any other macroblocks. 13. A method, according to claim 10, wherein the encoder using a second one of the reference buffers for error recovery includes: coding a macroblock using a second one of the reference buffers as a reference; and marking the selected one of the reference buffers as having an error. 14. A method, according to claim 13, further comprising: in response to marking the selected one of the reference buffers as having an error, the encoder se tting a timer to indicate an amount of time since the error occurred; and in response to the amount of time since the error occurred being greater than a predetermined threshold, the encoder clearing the error associated with the first one of the buffers. 15. A method, according to claim 14, wherein the predetermined threshold corresponds to a round trip transmission and processing time between the encoder and the decoder. 16. A method, according to claim 10, wherein a number of reference buffers used is increased in response to errors requiring the encoder to transmit at least one macroblock that is encoded independent of any other macroblocks and decreased if, after a predetermined amount of time, no errors requiring the encoder to transmit at least one macroblock that is encoded independent of any other macroblocks occur. 17. A method, according to claim 10, further comprising: associating each macroblock with a temporal reference number; and providing a table that maps each temporal reference number with one of a particular one of the reference buffers and a value indicating that a macroblock corresponding to a temporal reference number is not being stored. 18. A method of receiving video data from an encoder, comprising: a decoder receiving into a plurality of reference buffers a plurality of macroblocks that are coded relative to a plurality of reference buffers corresponding to the plurality of macroblocks; the decoder determining if there is an error with respect to a particular macroblock; and in response to an error with respect to a particular macroblock, the decoder indicating a selected one of the reference buffers associated with the particular macroblock is in error. 19. A method, according to claim 18, further comprising: following indicating an error in a selected one of the reference buffers, the decoder receiving a macroblock coded relative to a second one of the reference buffers. 20. A method, according to claim 18, further comprising: following indicating an error in the selected reference buffer, and in response to all reference buffers of the decoder having errors associated therewith, the decoder requesting at least one macroblock that is encoded independent of any other macroblocks. 21. A method, according to claim 20, further comprising: following requesting at least one macroblock that is encoded independent of any other macroblocks, the decoder resetting a timer; and the decoder forgoing requesting another macroblock that is encoded independent of any other macroblocks until the timer has exceeded a predetermined threshold. 22. An apparatus that transmits video data to a decoder, comprising: a plurality of reference buffers that store a plurality of macroblocks; a reference processor unit, coupled to said plurality of reference buffers, that provides at an output at least one motion compensation vector and a motion compensated image of a macroblock provided thereto; a difference unit, coupled to an input video signal and to said output of said reference processor unit, to provide a difference between the input video signal and said output of said reference processor unit at an output; and a coding controller that controls transmission of video data to provide each macroblock as one of: a macroblock that is encoded independent of any other macroblocks and a macroblock coded relative to said output provided by said difference unit; wherein, in response to an error for a macroblock corresponding to a first one of said reference buffers, said coding controller causes said reference processor unit to use a second one of said reference buffers for error recovery if there is no error associated with said second reference buffer. 23. An apparatus, according to claim 22, wherein, in response to all of the reference buffers having errors associated therewith, said coding controller causing transmission of at least one macroblock that is encoded independent of