| 摘要 |
A gas turbine engine exhaust nozzle 16 for reducing exhaust noise comprises a substantially frusto-conical nozzle wall 15,17, and a plurality of circumferentially disposed nozzle tabs 18,20 which extend in a generally downstream direction from a downstream periphery of the nozzle wall 15,17. The nozzle tabs 18,20 are radially inwardly angled at an angle ( b , fig 3) of up to 20{, but preferably up to 10{, relative to the nozzle wall 15,17. Preferably tabs 18,20 are trapezoidally shaped with trapezoidally shaped notches 21 or V shaped notches 19 between adjacent tabs 18,20. The angled tabs 18,20 are particularly suitable for a ducted fan gas turbine engine and can be provided on one or both of the core exhaust nozzle 14 or the bypass exhaust nozzle 12. Alternatively, a bypass exhaust nozzle 12 with angled tabs 18 can also be used with a core exhaust nozzle of the lobed mixer type. Broadband shock associated noise is improved by a frequency shift to more readily attenuated higher frequency noise and a reduction in noise at lower frequencies (fig 4).
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