ACOUSTIC RECONSTRUCTION OF THE UNSTEADY ROTATING FORCES OF FAN'S BLADE

This paper deals with noise sources in a cooling fan. The aim of this paper is to investigate the aero acoustic forces on the fan’s blade. A simple model based on the tonal noise produced by an axial fan is used in the direct problem. First the model is validated with a directivity experience. Validated model is then used to simulate acoustic pressure at known spatial positions in the radiated field. The discretized direct problem is associated with a regularization technique for inverse problem to estimate the unsteady rotating forces. Tikhonov regularization can provide an appropriate regularization parameter to improve reconstruction accuracy. The simulation reveals the possibility to reconstruct fan noise sources even with a perturbed measured acoustic signal. Obstacle on the fan suction mouth can be detected since it affects the aerodynamic forces.