Cédric Maury, Teresa Bravo and Daniel Mazzoni
Flinovia IV Flow-Induced Noise and Vibration Issues and Aspects
Del 22 al 24 de mayo de 2023, Sydney, Australia.
Enhancing the dissipation of low-frequency noise components in low-speed ducted flows is of paramount importance for the mitigation of exhaust pipes emissions in the automotive sector, but also to decrease the sound radiated by HVAC (Heat, Ventilating and Air Conditioning) diffusers towards residential areas. Typical resonant silencers such as expansion chambers, Helmholtz resonators or locallyreacting perforated liners are able to achieve high acoustical performance over a targeted bandwidth. But they also have to cope with aerodynamic constraints such as low frictional losses or minimal pressure drop [1] or to overcome aero-acoustic adverse conditions due to the generation of flow-silencer interaction noise, coined flow-induced noise, that impede the acoustical attenuation performance [2].
The current study evaluates the aero-acoustic efficiency of axially-graded resonating liners with micro-porous interface under a low-speed flow. The idea is to generate slow-sound effects from a distribution of varying cavity depths in order to trap and fully dissipate the incident acoustic wave over a specific bandwidth due to visco-thermal effects. Such concept has essentially been developed in the noflow case assuming closed-end conditions [3]. The micro-porous interface aims at shielding the liner from the flow effects to avoid flow-induced noise, but also to enhance the dissipated power and achieve minimal pressure drop. These issues will be studied from theoretical, numerical and experimental approaches.
