11th European Conference on Turbomachinery Fluid dynamics & Thermodynamics
The paper presents the further development of a combined acoustic-aerodynamic diagnostics method, suited to on-site investigation of industrial axial fans. The method, involving phased array microphone experiments, has been demonstrated in a case study. The acoustic data have been processed by means of a Rotating Source Identifier algorithm, and represented in the form of upstream and downstream source maps. A procedure has been reported for investigating the effect of duration of averaging on the phased array microphone results. A supplementary experiment has been elaborated for elimination of noise source ambiguity in evaluating the source maps. Certain rotor noise sources have been localised in a detailed manner. The momentum thickness parameter has been introduced and experimentally justified as a representative indicator of both aerodynamic loss and upstreamradiated noise. This offers a basis for fan redesign for reducing both noise and loss.