Session: 35-03/10-03 Joint session: Fan Noise

Paper Number: 153003

Relating Cutoff Pressure Distribution and Acoustic Signature of Centrifugal Fans Through Experimental Correlation 

Potential noise sources of rotating machinery are diverse and complex. This includes the acoustic signature of the impeller itself and the design of the fan casing. This is especially true for centrifugal fans with an asymmetric spiral casing. Here, a non-uniform and unsteady pressure field interacts with the volute cutoff, thus resulting in broadband noise radiation and, under given geometric circumstances, significant tonal noise effects. The current study investigates the relation between the local pressure distribution at the volute cutoff and the acoustic far-field signature of the fan. A low-speed centrifugal fan, placed in an anechoic environment, is equipped with pressure sensors to gather information on the mean pressure distribution as well as the unsteady wall pressure field at selected spots. Correlating the captured signature with the radiated far-field noise reveals significant common spectral components and helps identify relevant noise sources, affected by the volute cutoff. In the long term, the definition of transfer functions between the near-field wall pressure and the radiated noise into the far-field is expected to enhance the geometric optimisation of the volute cutoff in both experimental and numerical environments. The test rig, being in close agreement with ISO 5801, allows to simultaneously capture the aerodynamic performance, allowing for an analysis of the pressure correlation along the entire characteristic curve.

Presenting Author: Till M. Biedermann TH Nürnberg Georg Simon Ohm

Presenting Author Biography: After taking the lead of R&D at the Pollrich Fan Factories for heavy-duty industrial fans, Till Biedermann is a Professor for Turbomachinery and Technical Acoustics at Technische Hochschule Nürnberg Georg Simon Ohm since October 2023. His main research topics are located in the area of aeroacoustics and aerodynamics of rotating machinery, more precisely he addresses challenges in the multi-objective optimisation of axial and centrifugal fans through numerical and experimental methods.

Authors:

Till M. Biedermann TH Nürnberg Georg Simon Ohm
Dennis Kammerzelt TH Nürnberg Georg Simon Ohm