A numerical study of noise characteristics originating from a shrouded subsonic automotive fan
(English)Manuscript (preprint) (Other academic)
The characteristics of the noise radiated from a reduced automotive cooling module is numerically studied with focus on the interaction eﬀects linked to the sound generation mechanisms and the acoustic scattering caused by the conﬁned installation. The ﬂow ﬁeld is simulated by adopting the formulation of IDDES, which is a numerical technique that enables large scale structures to be resolved and the wall-bounded ﬂow to be treated either in DDES or WMLES depending on the turbulent content within the boundary layer. By comparing the simulated fan performance to two sets of experimental data of a similar setup, the aerodynamic results obtained from IDDES are validated and conformed to the volumetric ﬂow rate delivered for the pressure drop measured. The acoustic part of the study comprises evaluation of the sound source associated with the momentum distribution imposed on the surroundings at an interface slightly upstream the fan. At the microphone positions upstream the installation, the SPL falls within the SPL range measured and the acoustic power delivered by the fan conforms to the SWL obtained from the comparison method in the reverberation room. The system response function, estimated by subtracting the SWL for the free-ﬁeld simulation from the SWL associated with the reduced automotive cooling modulemarks spectral humps at ﬁxed frequencies, irrespectively of sound source. As such, the engineering approach to spectral decomposition method earlier published which, enables isolating the acoustical properties of the installation from the source, is validated and found to hold.
Fan noise, Installation eﬀects, Spectral decomposition, IDDES, FW-H, Aeroacoustics
Fluid Mechanics and Acoustics
Research subject Vehicle and Maritime Engineering
IdentifiersURN: urn:nbn:se:kth:diva-199280OAI: oai:DiVA.org:kth-199280DiVA: diva2:1061739
QC 201601042017-01-032017-01-032017-01-04Bibliographically approved