Results of verification of the numerical method for calculation of hydrodynamic and hydroacoustic charachteristics of the fin propulsor

Abstract

This work employs numerical methods of viscous fluid dynamics for determination of hydrodynamic and hydroacoustic characteristics of the oscillating wing as the major structural element of the fin propulsor. Verification of the calculation methods with subsequent analysis of the fin propulsors of more complex designs was carried out by means of comparison of numerical results against respective analytical solutions and experimental data. Hydrodynamic characteristics were determined based on the numerical solution of the Reynolds-averaged Navier—Stokes equations supplemented by the realizable model of turbulence. Rotation of the wing in the water flow was ensured by the mechanism of «sliding computation meshes» implemented in many computing software packages of mechanics of fluids and gases. Hybrid approach to mathematical modelling was described to assess the noise produced by the fin propulsor in the far field using the Ffowcs Williams—Hawkings equation. Verification of this method was based on comparison of the calculated results against experimental values of levels of acoustic pressure when viscous gas flows around the cylinder. The calculated values of pressure fluctuation amplitudes in the far field produced by wing oscillations were compared against analytical estimations obtained by means of modelling of the effect that concentrated fluctuating force (presented as dipole) produces on fluid. The proposed calculation approaches can be used for designing perspective propulsion systems based on the oscillating wing.