Development Of Nosie And Vibration Signal Processing System For Ship Tests

With the rapid development of modern technology, the vibration and noise reduction technology of modern ships and submarines is one of the most important research topics, and the signal processing research is the essential part. As an important source of noise signal, research of propeller vibration and hydrodynamic noise are of great values.Based on the requirements of marine engineering, signal analysis and processing technical specifications of noise and vibration reduction for ship testing, this essay developed user-friendly interface, complete function of the vibration, noise and wavelet analysis of signal processing system.This system mainly consists of three function modules, the propeller vibration signal processing module, the hydrodynamic noise signal processing module and the wavelet analysis and the noise reduction module. The analysis process contains two parts, the processing of original signal and wavelet denoising.Reading files is the first part of signal processing, and this system can transforms the original data to a standard format, so that different types of signal can be processed by different modules. The three function of this system are described as follows. Firstly, the propeller vibration signal processing module can realize the original vibration signal analysis in both time and frequency domain, wavelet de-noising and wavelet analysis. Secondly, hydrodynamic noise signal analysis modules can achieve analysis such as the sound quality characteristics, frequency spectrum, sound pressure level, waterfall graph, octave results, wavelet denoising and wavelet analysis. Finally, according to the analysis of the original signal and noise processing results, this system can save data, analyze signals, draw corresponding graphs and generate an acoustic analysis report automatically.In this paper, the detail vibration and hydrodynamic noise analysis theory and algorithms of signal processing are discussed. Based on the Fourier transform, combined with wavelet analysis and noise reduction methods, a detailed description of how to realize this software system are presented, including time domain, frequency domain, wavelet analysis and report generation automatically. Finally, this system is verified by the actual vibration data of propellers. The results show that this system is of big value for both engineering and research purpose.