A study on the flow and noise of a pump-jet propulsors in the fully appended SUBOFF hull wake

Noise suppression in propulsion systems constitutes a critical pathway for advancing submarine stealth capabilities. As a core propulsion component, the hydrodynamic and noise performance of pump-jet propulsors (PJPs) is fundamentally governed by parametric design optimization and hydrodynamic compatibility with hull configurations. This study systematically investigates the hydrodynamic and noise characteristics of a PJP integrated with a fully appended SUBOFF submarine hull, with particular emphasis on duct parameter effects. The computational framework combines improved delayed detached eddy simulation (IDDES) with the Ffowcs Williams-Hawkings (FW-H) acoustic analogy to resolve hydrodynamic and acoustic fields under self-propulsion and non-self-propulsion operational conditions. After comparing the prototype's results with the experiments, the thrust fluctuation is first analyzed to reveal the influence mechanism of duct. Then, the far-field radiation noise characteristics with different ducts in the self-propulsion conditions are presented. Finally, the flow features of the PJP and hull tail and the influence mechanism of these duct main parameters are discussed. Results show that the PJP performance and thrust fluctuations change noticeably owing to different duct parameters in the effective wake. This work enhances the understanding of how the duct influences the thrust fluctuation, flow, and noise of a PJP-propelled submarine system. Specific reference values of duct parameters are established to optimize propulsion efficiency and noise characteristics, contributing to the overall design of PJP.