倾斜结构对三股流喷管流场及声场影响机理研究

The flow and noise mechanism of the three-stream nozzle and the influence of the asymmetric structure on the flow and noise characteristics were studied by numerical simulation. The results show that although the tertiary stream avoids the direct contact between the high-speed fan flow and the free stream，and reduces the mixing intensity between the jet and the free stream，the tertiary stream with small bypass ratio is uniformly distributed along the circumference due to the restriction of the axisymmetric structure，its noise reduction effect is limited in all directions，and its impact is small on the distribution of the nozzle overall sound pressure level. When the asymmetric structure of the tertiary stream is added，the bypass ratio increases，the mixing intensity between the end of the primary potential core and the free stream decreases，and the overall sound pressure level at 30°observation angle decreases by about 2.6dB compared with the axisymmetric structure. Considering the bypass ratio matching of the tertiary stream，the asymmetric structure is profiled designed to control the bypass ratio and the outlet flow angle. The reduction magnitude of the mixing intensity between the end of the primary potential core and the free stream at the lower side of the nozzle is lower than that of the asymmetric structure without controlling the bypass ratio. The overall sound pressure level at 30°observation angle decreases by about 1.5dB compared with the axisymmetric structure.