Numerical investigation of hydrodynamic and hydro-acoustic performance of underwater propeller operating in off-design flow conditions

Abstract

ABSTRACT This paper is aimed to numerically investigate the hydrodynamic and hydro-acoustic behaviours of rotating underwater propeller operating in off-design flow conditions. The performance of the propeller is subjected to significant alteration, as it experiences flow, coming at an angle. For this purpose, numerical simulation is performed for the INSEAN Propeller E779A. Turbulence model based on the two-equation Reynolds Averaged Navier Stokes (RANS) turbulence model, i.e. k–ω SST (Shear Stress Transport) method is implied to assess hydrodynamic performance, while hydro-acoustic assessment in near field is calculated by coupling RANS with the Ffowcs Williams Hawking (FW-H) equation. Validation is performed by comparing the numerically computed results from the current study with the available experimental data in straight flow conditions and then the off-design conditions are modelled by using the combinations of three advance ratios with four different flow angles. As a result, distinct differences among the hydrodynamic and hydro-acoustic features are analysed. The hydrodynamic coefficients are compared, and their change is analysed in detail. For the hydro-acoustic analysis, sound pressure level, attenuation frequency and directivity analysis are conducted and based on these factors the effect of the off-design condition on the aquatic life is discussed, thus showing the strong influence of the off-design condition on the hydro-acoustics of the underwater water propeller.