Investigation on the Noise of an Axial Low Mach-Number Stage with a Heterogeneous Stator

Noise Generation Mechanisms

A low-Mach number ducted axial fan from an aircraft air-conditioning system is investigated in this study. This configuration has a short rotor-stator distance and a heterogeneous (non-periodic) stator row. Those features strongly modify the rotor-stator noise-generation mechanisms. Two numerical simulations with the original heterogeneous and a homogeneous OGV are performed using the Lattice-Boltzmann Method (LBM). A comprehensive acoustic analysis is made upstream of the fan in order to retrieve the spectral and modal content of the noise. The direct comparison of the homogeneous and heterogeneous configurations provides the quantification of the impact of a heterogeneous stator. Finally, the dominant modes caused by the stator heterogeneity are identified by comparing with an experiment.