Prediction of the blade trailing-edge noise of an axial flow fan

The objective of this work is to predict the trailing-edge noise of axial fans with an analytical model deduced from an extension of Amiet's formulation. The input data of the acoustic model are the frequency spectra and the spanwise correlation length scales of the wall-pressure fluctuations on the blade suction side close to the trailing edge. This model was successfully validated in former studies on single steady airfoils in anechoic wind tunnels and, to a lesser extent, on an axial fan equipped with small unsteady pressure transducers flush mounted on the blade suction side. The present research is carried out on a 6-blade axial fan no longer equipped with embedded pressure transducers. The input data of the prediction are then deduced from non-dimensional spectra and correlation lengths of the pressure fluctuations measured in the previous study and RANS simulations performed on the test fan. A validation of the prediction method is made by comparing the predicted and measured sound power spectra of the fan for two blade pitch angles and different operating points.