Direct aeroacoustic simulation of a cross-flow fan with Helmholtz resonator using lattice Boltzmann method

Abstract

It is necessary to reduce the aerodynamic sound generated by fans since they are often used for air-conditioners, which are placed in human living areas, such as homes and offices. To reduce the aerodynamic sound, we focused on the Helmholtz resonator. To develop a resonator-type silencer for the aerodynamic sound of air-conditioners, the present study investigated the flow and acoustic fields around a cross-flow fan with a resonator and the effectiveness of the resonator for blade-passing frequency (BPF) sound using aeroacoustic simulations. As a numerical method, we used the lattice Boltzmann method (LBM), which can simultaneously simulate aerodynamically sound generation in the fan and the acoustic resonance in the resonator. Consequently, the simulation results showed that a reduction of 2.9 dB for the BPF sound can be realized by installing a resonator in the tongue part of the fan casing.