Noise Prediction of Axial Fan Duct using a Lattice Boltzmann Approach and Acoustic FEM

Large axial fans in fire power plants are noise source of the plants, they are required to reduce the noise level. Fan noise propagates in a fan duct, and since it is emitted to the exterior, silencers are used as countermeasure in general. It is important for noise reduction to predict noise generation and noise propagation in fan ducts. The Lattice-Boltzmann Method (LBM) based approach was applied for the unsteady simulation of axial fan and its duct to predict fan noise generation. The LBM has minute numerical viscosity, and is suitable for the analysis of sound propagation and flow field. In this research, aeroacoustic analysis by using applicable analysis model in the design phase has been conducted and validated compared to experimental results. In addition, acoustic FEM has been conducted and validated in order to design the low noise structure like a silencer. The results shows good agreement with experiment within 3dB at overall value and predicted spectra are also compared with experimental results.