Abstract
Flow-induced noise from the sail hull, which is induced by the horseshoe vortex, the boundary layer separation and the tail vortex shedding, is a significant problem for the underwater vehicles, while has not been adequately studied. We have performed simulations and experiments to reveal the noise generation mechanism from these flows using the scaled sail hull with part of a submarine body. The large eddy simulation and the wavenumber–frequency spectrum are adopted for simulations. The frequency ranges from 10 Hz to 2000 Hz. The simulation results show that the flow-induced noise with the frequency less than 500 Hz is mainly generated by the horseshoe vortex; the flow-induced noise because of the tail vortex shedding is mainly within the frequency of shedding vortex, which is 595 Hz in the study; the flow-induced noise caused by the boundary layer separation lies in the whole frequency range. Moreover, we have conducted the experiments in a gravity water tunnel, and the experimental results are in good accordance with the simulation results. The results can lay the foundation for the design of flow control devices to suppress and reduce the flow-induced noise from the sail hull.
Highlights
With excellent concealment, submarines are one of the most critical naval weapons in the ocean.the noise radiated by the submarines during movement is a direct threat to their safety, and noise control of submarines has become a hot issue nowadays
The results of the flow field calculation are dealt with by the fast Fourier transform (FFT), and of the flow fieldincalculation are dealt with by the fast (FFT), and the The data results of fluctuation pressure the time domain is converted into theFourier data intransform the frequency domain
Since the boundary layer separation is variable in the process of the leading edge of the sail hull is mainly excited by the horseshoe vortex, which contributes very little to the flow‐induced noise in the high‐frequency range
Summary
Submarines are one of the most critical naval weapons in the ocean. Because the water is the dense medium, of which the acoustic impedance is approximately equal to that of the submarine, the feedback of the acoustic field to the flow cannot be considered as small or neglected Another difference in the results between the two is the experimental measurement. In our study, based on the theory of numerical simulation [24], we have proposed the method to calculate the flow-induced noise from the model of the sail hull with part of the submarine body. We have investigated the generation mechanism of the flow-induced noise from three kinds of the flow phenomena around the sail hull and part of the submarine body, which are the horseshoe vortex, the boundary layer separation, and the tail vortex shedding. The analysis of the generation mechanism of the flow-induced noise is validated by the experiments
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