关键词: 热喷流；锯齿型喷口；分开式排气；挂件；喷流噪声

Abstract: The hot jet noise reduction of chevron nozzles with pylons was investigated on separate flow nozzles at a bypass ratio of 5.5. All the experiments were conducted on the hot jet noise rig located in the anechoic chamber. The effects of the chevron nozzles on far-field jet noise reduction were explored，such as structural parameters and their distribution. The experimental results of hot jet noise with pylons show that chevron nozzles reduce jet noise in the low frequencies and have the best low-frequency noise reduction at downstream. The distribution of chevrons was determined to be a primary factor in jet noise reduction. The high-frequency noise controlling was observed when chevrons were fixed only in primary nozzles which have the reduction in overall sound pressure level ranging from 1.4 to 2.4dB at downstream. Besides，the increase of chevron counts also has the ability of noise suppression in high frequencies. Slight differences were observed when varying chevron penetration angles，but it appears that the effect is less significant than the effect of distribution.

Key words: Hot jet；Chevron nozzles；Separate flow；Pylon；Jet noise