Flow noise characteristics in a three-way pipe and its bionic optimization

To investigate the influence of different three-way pipe angles on internal flow noise characteristics, this study employs large eddy simulation (LES) and the acoustic finite element method (FEM) to conduct numerical simulations of the flow field and internal acoustic field for three different pipe angles (30°, 60°, and 90°). The results indicate that as the angle of the three-way pipe increases, pressure pulsation decreases along the main pipe direction while increasing along the branch pipe direction. The low-speed vortex region near the lower wall of the main pipe outlet and the high-speed vortex region near the lower wall of the branch pipe outlet are significantly weakened. The internal flow noise energy at the main pipe inlet/outlet and branch pipe outlet is primarily concentrated in the 1–10 Hz and 1–20 Hz frequency ranges, respectively, with the branch pipe outlet exhibiting slightly higher sound pressure levels than the main pipe inlet/outlet. Moreover, as the three-way pipe angle increases, the overall sound pressure level (OSPL) at the main pipe outlet shows the most significant reduction with a decrease in 12.3%. Bionic optimization of the 90°three-way pipe further reduces an 11.9% reduction in the OSPL at the branch pipe outlet.