Numerical and Experimental Investigation of Aerodynamic Noise Generated by Subsonic Axial Fan Using Hybrid Approach

Abstract

This research work reports the study and investigation of aerodynamically generated noise characteristics of the fan using a hybrid numerical approach. Numerical results are compared with the experimental results. The experiment is conducted to determine the sound power radiated by the fan. This experiment is carried out in the reverberant and anechoic chambers as a test environment. The axial subsonic fan is considered for the study. Detailed experimental work is reported in the first section, and in the second section, numerical simulation results are reported. Flow analysis is carried out using unsteady Navier Stokes based equations with a Large Eddy Simulation scale resolving turbulence model in the commercial solver Ansys Fluent. Fluctuating components of velocity and density are computed for further calculation of acoustics. The flow results from the simulation are compared with the flow results obtained in the experiment. As the aerodynamic performance of the fan is validated and shows good agreement with experiment, it is followed by an aeroacoustics analysis performed in the MSC Actran Acoustics solver. The Lighthills analogy is used to compute the flow noise generation and propagation terms. Sound power characteristics are studied with the help of one third octave band and narrow band analysis. Overall sound power is computed in MSC Actran and is compared with the experiment. Also, the sound power computed in Ansys Fluent is compared with an experiment and shows good agreement This work also reports the detailed computational methodology for fan noise prediction for any type of fan application