Investigation On Characteristics Of Propeller Hydrodynamic Noise

Propeller is widely used for ship propulsion. With the improvement of ship safty and comfort, many countries have adopted strict standards in ship noise control. It is necessary to study the characteristics of propeller hydrodynamic noise. Based on the computational fluid dynamics, the standard propeller DTMB P4119 has been used. The turbulence model combined with FW-H acoustic analogy equation are used in the software FLUENT. The propeller hydrodynamic performance is analyzed, and the hydrodynamic noise under the critical speed is researched .Firstly, the five common FLUENT turbulence models: standard k-? model, RNG k-?model, realizable k-? model, SST k-? model and LES are adopted. According to references,the propeller flow model is established. The five turbulence models were used to calculate the steady thrust, torque and efficiency in the open water. Then the calculated results are compared with the experimental data. The effects of the boundary layer, the grid cell size and the number of cell on cost acaracy are studied.Secondly, under the advanced speed ratio of 0.833, the unsteady situations is considered,and the propeller thrust, horizontal and vertical force, together with the propeller torque ,horizontal and vertical bending moments are studied and analyzed in the paper using the sliding mesh. In additions the effects of the propeller flow field, the number of revolutions per minute, and the speed on the hydrodynamic performance of the propeller are studied.Thirdly, the effects of the shaft vibration on the propeller hydrodynamic performance are studied. The numerical simulation modal of shaft is built,and the characteristics of shaft vibration and response are researched. The vibration amplitude, frequency and phase of propeller on shaft are getted. In addition, the results are imported to calculate of the propeller hydrodynamic performance. The results show that the frequency spectrum of the propeller hydrodynamic performance contains the nature characteristic of shaft vibration.Finally, using the simulation results for hydrodynamic performance, combined with FW-H acoustic analogy equations, propeller hydrodynamic noise is researched, and the effects of the each factor mentioned above on propeller hydrodynamic noise is investigated. The effects of these factors on the acoustic field directivity, the distribution of overall pressure lever and the characteristic of the acoustic field point are studied.