Numerical Calculation of the Radiated Noise of Contrarotating Propellers

Abstract

Based on the hybrid methods of cavitation transient simulation of multiphase flow and the boundary element numerical acoustic calculation, the noise of contrarotating propellers in states of cavitation and non-cavitation is calculated, the increase quantity of the noise spectrum level in cavitation relative to in non-cavitation condition is analyzed; the calculated noise value and the tested value are compared. The multiphase flow transient simulation includes three simulations: unsteady Reynolds-averaged Navier-Stokes method (URANS), scale adaptive simulation (SAS) and detached eddy simulation (DES). The testing result shows that the open water performance curve of propellers coincides well with the experimental result in the range of large range of feed coefficient. SAS presents a comparable ability with DES in capturing the pulsating pressure of cavitation and can respond well to the unsteady load noise. RANS (Reynolds-averaged Navier-Stokes) is appropriate for the low frequency noise. The calculating error of line spectrum cavitation volume pulsation 1 kHz is less than4.23 dB, and the average error of spectrum level 1/3 Octave band is less than1.83dB in the frequency band of 1 kHz-3kHz, and the predicted error of the total sound pressure level is less than 2.74dB, And the attenuation coefficient of sound pressure level with is calculated by simulation, which can provide certain help for the design and the noise prediction of propellers.