Beamforming Based Extension of Semi-Empirical Noise Modelling for Low-Speed Axial Flow Fans

The application of the turbulent boundary layer trailing edge (TBL-TE) noise component of the semi-empirical Brooks-Pope-Marcolini (BPM) model in an axial flow fan case study is presented herein. The spanwise distribution of the strength of the emitted TBL-TE noise was estimated using the model for various rotational speeds, taking inlet axial velocity profile measurements and two-dimensional (2D) empirical aerodynamic cascade correlations providing input data to the model. The calculated source strength distributions were compared to corrected beamforming results from phased array microphone measurements. In the frequency ranges dominated by the TBL-TE noise, the applicability of the BPM model has been confirmed to circular-arc cambered plate blades, over extensive ranges of geometrical and aerodynamic parameters.