Numerical Study on the Influence of Rudder Fillets on Submarine Wake Field and Noise Characteristics

The submarine rudder configuration and arrangement significantly impact its hydrodynamic performance. This paper takes the SUBOFF standard submarine model as the research object, constructs a geometrically parameterized rudder fillet structure based on parabolic parametric equations, and adopts the improved delayed separation vortex (IDDES) turbulence model to carry out numerical simulation research on the submarine rounding flow field with crossed and “X” rudder configurations. By comparing and analyzing the effects of different fillet parameters and rudder layouts on the generation mechanism of the horseshoe vortex, vortex system strength characteristics, and the distribution of the wake companion flow field at the velocity of 7.161 m/s, it is found that the introduction of the rudder fillet structure can effectively destabilize the horseshoe vortex and significantly reduce the axial velocity inhomogeneity of propeller plane. In addition, the improvement effect of the flow field in the near-axis region (r/R ∈ (0, 0.5)) is particularly significant. Compared with the crossed rudder, the “X” layout shows better flow control performance, with the maximum reduction in the axial relative velocity of the propeller plane surface reaching 49.34%, which is 24.25% higher than that of the SUBOFF baseline model, and the addition of two distributions of rudder fillets can reduce the hydrodynamic noise of the submarine by 4.6 dB vs. 5.6 dB at most. The results provide an essential hydrodynamic basis for optimizing the submarine rudder system.