This presentation investigates the noise characteristics of radial fans with forward curved blades by performing CFD simulations with the emphasis on employing different turbulence models (RANS/URANS, DES, LES) and unstructured grids.
The noise radiated from the fan is calculated with the aeroacoustic models provided by STAR-CCM+ (e.g. FW-H) and correlated with the results obtained from the hybrid approach (using ACTRAN) as well as the experimental results obtained from duct method according to DIN EN ISO 5136.
The predicted noise spectra obtained from the simulations are in good agreement with the experimental results, specially the overall trend of the experimental curves as well as the Blade Passing Frequency (BPF) is correctly predicted. Meanwhile, monitoring transient surface and volume data helped to gain insight into the noise radiated from different parts of the system, e.g. blades that could not be easily obtained from the charts and diagrams.
It is concluded that the DES model can effectively be used for aeroacoustic simulations and depending on the physics of the flow, it is not always necessary to perform time consuming LES simulations.