A Finite-Element-Simulation Workflow to Investigate the Aero- and Vibro-Acoustic Signature of an Enclosed Centrifugal Fan 2024-01-2940

Centrifugal fans are applied in many industrial and civil applications, such as manufacturing processes and building HVAC systems. They can also be found in automotive applications. Noise-reduction mea- sures for centrifugal fans are often challenging to establish, as acous- tic performance may be considered a tertiary purchase criterion after energetic efficiency and price. Nonetheless, their versatile application raises the demand for noise control. In a low-Mach-number centrifugal fan, acoustic waves are predominantly excited by aerodynamic fluctu- ations in the flow field and transmit to the exterior via the housing and duct walls. The scientific literature documents numerous mech- anisms that cause flow-induced sound generation, even though only some are considered well-understood. Numerical simulation methods are widely used to gather spatially high-resolved insights into physical fields. However, for a centrifugal fan, the numerical simulation of the coupled aero- and vibroacoustic sound emission faces several hurdles, including a tedious meshing procedure, rotating parts, and the dispar- ity of physical scales that need to be resolved for the acoustic field, the flow field, and the mechanical field. This work thus suggests a hybrid workflow to simulate sound generation and the through-wall sound transmission of an enclosed centrifugal fan. The workflow is based on three consecutive simulation runs: 1) a finite-volume-based in- compressible CFD simulation to determine the low-Mach-number flow field, 2) a finite-element-based computational aeroacoustic simulation to determine the in-duct sound field, and 3) a finite-element-based vi- broacoustic simulation that solves for the direct-coupled mechanic- acoustic simulation to determine the through-wall sound transmission. Additionally, an exemplary simulation of a test fan is conducted and discussed.