Numerical prediction of near-field acoustic pressures induced by a ducted propeller using a BEM/FW-H method

초록

In this article, a boundary element method is coupled with an acoustic analogy, the Ffowcs Williams-Hawkings formulation, to be applied to a ducted propeller problem to investigate its noise characteristics. The main purpose is to study the duct baffling effect on noise propagation compared to open propeller noise mainly in the near-field, and deduce which one produces more noise when both generate the same amount of thrust. The hydrodynamic boundary element method is first implemented for the analysis of propeller performance, and the predicted noise sources (hydrodynamic quantities) are fed into the acoustic analysis code for the subsequent acoustic analysis. During the process, the propeller and duct geometries do not require any simplifications on their geometries, and the compressibility delay is taken into account to fully consider the time travel of propagating noise. Based on the predicted results, the contributions of the blade-induced noise, duct-induced noise, and their sum as total noise are separately investigated to identify their individual impacts on the overall noise characteristics. Tests are also performed under different loading conditions and with different propeller geometries to see how the operating conditions affect noise patterns in the presence of the duct. Numerical predictions are compared to experimental measurements, results from the hydrodynamic boundary element method (without coupling with the acoustic analogy), and viscous Reynolds-averaged Navier-Stokes simulations to investigate the feasibility, usefulness, and limitations of the present method. © 2025 Elsevier Ltd

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