Numerical Investigation of the Flow and Acoustic Contributions to a Water Jet Propulsor

Water jet propulsor (WJP) is an integrated propulsion system comprising a stator, rotor, and duct. Limited research exists on characterizing the flow and acoustic properties of individual components. This study employs improved delayed detached-eddy simulation with the Ffowcs Williams and Hawkings method to analyze flow patterns and noise generation around a WJP. The numerical results demonstrate strong correlation with experimental data, enabling detailed analysis of both internal and wake flow fields. Findings indicate that the WJP wake exhibits an axisymmetric conical flow field without a distinct stable region in its trajectory. The vortex passing through the nozzle rapidly transitions to an unstable state. Increased rotation speed results in greater wake wave height, decreased trailing angle, and pronounced secondary vortex formation in the unstable region. The study examines WJP flow noise characteristics and component acoustic contributions using energy method analysis. Directional variation in WJP flow noise reveals distinct component contributions: maximum overall sound pressure level occurs at the rear, where the rotor set contributes 90%, while at the sides and bottom, the rotor set accounts for 77% of acoustic output.