A Comparative Numerical Study of Hydrodynamic and Acoustic Performance Between Contracted and Loaded Tip Pump-Jet and Conventional Pump-Jet

Abstract

This study employs a Contracted and Loaded Tip (CLT) propeller to replace the conventional pump-jet rotor, and a comparative analysis is conducted using the Detached Eddy Simulation (DES) method. The reliability of the numerical method is first validated through open-water tests. The CLT pump-jet propulsors are systematically investigated in two series: the varying endplate width (CW) and varying endplate length (CL). The results indicate that varying the endplate width has a significant impact on the hydrodynamic performance. A smaller width leads to a more pronounced decrease in the thrust coefficient, torque coefficient, and efficiency. In contrast, varying the endplate length primarily affects the efficiency at high advance coefficients. Regarding the vortical characteristics, the gap region is dominated by the tip leakage vortex (TLV) and tip separation vortex (TSV), whose intensity and evolution are influenced by the endplate structure. A reduced endplate width expands the low-velocity region within the gap, while an increased length contributes to a more stable vortex development. In terms of the noise performance, the varying-width designs effectively suppress pressure fluctuations and achieve noise reduction. Specifically, the CW3 model exhibits maximum reductions in the overall sound source level of 5.7 dB and 4.0 dB at distances of 1 m and 20 m, respectively. Conversely, the varying-length designs intensify the pressure fluctuations and show no significant noise reduction effect.

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