A method for estimating the suppression effect of air bubbles on the characteristic frequency of propeller sound source

Abstract

The invention discloses a method for estimating the inhibiting effect of a bubble cluster for propeller sound source characteristic frequency. The method comprises the following steps: (1) collectingpropeller noise signals in different working conditions; (2) calculating the noise signals by using a cyclostationary characteristic function to obtain circulating density spectrums; (3) carrying outpoint division on the circulating density spectrums corresponding to the two working conditions, or using a minimum two-norm method to obtain circulating a density spectrum for a bubble transfer function; (4) according to the circulating density spectrum obtained in the step (2), calculating a circulating coherent spectrum to construct an enhanced envelope spectrum under logarithmic coordinates; (5) judging characteristic frequency according to the enhanced envelope spectrum, and carrying out splicing corresponding to the characteristic frequency on the circulating density spectrum for the bubble transfer function to obtain a bubble cluster transfer function; and (6) according to the bubble cluster transfer function, estimating the inhibiting effect of the bubble cluster for propeller sound source characteristic frequency. By using the method, more accurate transfer function can be obtained, so that the isolation effect of the bubble cluster is analyzed preferably.

Description

technical field [0001] The invention belongs to the field of signal processing and feature extraction, in particular to a method for estimating the suppression effect of bubble groups on the characteristic frequency of propeller sound source. Background technique [0002] Transparent air bubbles in water are easy to deform, split, and fuse, and the acoustic characteristics of water containing air bubbles are also significantly different from those of pure water. Since the bubble group is a strong scatterer in water, it has a strong attenuation and scattering effect on the transmitted sound waves. When the bubbles in the water resonate, the attenuation effect on the sound wave near the resonance frequency of the bubbles is more obvious. However, the transfer function characteristics of the bubble group are difficult to be directly described by mathematical formulas. Therefore, the study of the acoustic properties of bubble groups in water has extremely important scientific ...

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Problems solved by technology

[0006] However, there are following shortcomings and deficiencies in the prior art: Fault detection methods such as Fourier transform, short-time Fourier transform, wavelet transform, second-generation wavelet transform and multi-wavelet transform are all based on the assumption that the signal is a stationary signal, and In reality, it is often a non-stationary signal, so these detection methods are unreasonable and unrealistic

At the same time, due to theoretical limitations, these traditional detection methods are difficult to detect some important features of rotating machinery, such as blade passing frequency BPF, blade ratio frequency BRF, etc., which have great limitations

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