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 measures for centrifugal fans are often
challenging to establish, as acoustic 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
fluctuations in the flow field and transmit to the exterior via the housing and
duct walls. The scientific literature documents numerous mechanisms that cause
flow-induced sound generation, even though not all of them 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 disparity 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 incompressible 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 vibroacoustic 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.