Parameter study on aerodynamic noise of the benchmark ventilation duct

Abstract In many industrial applications, ventilation ducts are used to control the direction and flow rate of air. To control the aerodynamic noise of ventilation ducts and develop effective noise reduction measures, it is necessary to clarify the mechanisms and propagation characteristics of the noise sources. This paper uses Computational Fluid Dynamics (CFD) methods combined with Lighthill acoustic analogy to simulate aerodynamic noise in a benchmark ventilation duct model that is widely recognized in the industry, and the simulation accuracy is validated by experimental data. It is indicated that the Lighthill acoustic analogy is suitable to predict the far-field noise generated by the ventilation duct. Then, the method is used to study the influence of inflow speed, duct bending angle, and flap angle on the aerodynamic noise. The simulation results show that flow separation occurs downstream of the bending configuration and flap, increasing the pressure fluctuations and thus inducing additional aerodynamic noise. The sound pressure level increases with the flow speed and flap angle gradually. However, the noise level of the cases with bending angles smaller than 30°are very close, which could suggest a critical value of the duct curvature. The noise sources and the contributions of different components are analyzed, and it is indicated that the flap is the main sound source in the studied case. This work helps clarify the aerodynamic noise generation mechanisms and lays the foundation for the development of noise reduction technology in the future.