Contribution
Vibroacoustic Investigation of the Thin-Walled Duct System and Fan Housing in an Aeroacoustic Test Rig
* Presenting author
Abstract:
In ducted ventilation systems, the noise generated by the operating fan reaches the exterior via two paths: 1) through duct openings, e.g., at the very end of the duct, or 2) by transmission through the duct walls, often referred to as "breakout". Acoustic breakout may account for a significant proportion of the produced total sound emission, depending on various parameters such as the construction material, the wall thickness, and the duct cross-section. Understanding the sound-transmission properties of the duct can thus be essential for classifying the sound emission of a ducted ventilation system. This work investigates the sound-transmission properties of the duct system for a centrifugal fan embedded in an aeroacoustic test rig. In particular, the fan's spiral housing and the connected thin-walled duct with a rectangular cross-section are investigated via finite-element simulations of the mechanical structure and the interior acoustic field. The mechanical model is tuned to and verified by 3D laser vibrometry scans on parts of the structure. The exterior sound radiation is classified through the transmission loss of the interior sound field. The focus lies on the interaction between the interior-acoustic and the mechanical modal fields, considering a purely acoustic excitation of the mechanical structure.