SUMMARY EVALUATION OF TOOTHED-NOZZLE ATTACHMENTS AS A JET-NOISE-SUPPRESSION DEVICE

摘要

Toothy-d attachments to a full-scale turbojet nozzle were investigated lonpoaible jet-noise reduction and thrust penalty. The attachment can delight reductions, in total sound power that are insignificant when evaluated in term., of engine thrust losses and aircraft payload penalty. At the reduced thrust levels obtained with the toothed nozzles, corresponding sound power reductions could be realized by throttling the standard turbojet engine.nSound pressure levels were reduced behind the engine but were in where. A typical resident in the airport neighborhood would hate increased loudness in the middle frequencies} however, the resulting over-all auditory effect is considered to be negligible.