船舶螺旋桨噪声远场湖泊试验研究

Experimental Study on Far-Field Lake Noise of Ship Propellers

摘要: 船舶螺旋桨噪声特征可作为水下目标识别与声隐身的依据。研究在严格远场条件下开展水下背景噪声系统性试验，涵盖水听器接收性能测试、湖泊背景噪声测试、静态2叶片螺旋桨噪声特性及实船航行螺旋桨噪声特征分析。采用时域统计、多维度频域分析(单边幅值谱、对数频谱、Welch功率谱密度)、时频联合分析(STFT、CWT小波变换)及LOFAR低频精细谱等方法，结合MATLAB进行信号处理，获取了典型水下噪声源的多维度特征图谱。结果显示，某湖背景噪声呈10~100 Hz宽带平稳、中高频−9 dB/oct衰减特征；螺旋桨噪声以离散谐波线谱为核心标识，静态非空化时叶频最强，较轴频高10~20 dB，实船航行时轴系不平衡与流场非对称可使轴频成为主导分量。试验结果可为水下目标识别、背景噪声抑制及声学系统设计提供可复现的试验依据。

Abstract: The noise characteristics of ship propellers serve as the basis for underwater target identification and acoustic stealth technology. In this study, systematic underwater ambient noise measurements were performed under strict far-field conditions, including hydrophone calibration, in situ ambient noise testing of a freshwater lake, noise measurement of a static two-blade propeller, and noise feature analysis of ship propellers under sailing conditions. Combined with MATLAB-based signal processing, multiple analytical methods were adopted: time-domain statistical analysis, multi-dimensional frequency-domain analysis (one-sided amplitude spectrum, logarithmic spectrum, Welch power spectral density), time-frequency joint analysis (Short-Time Fourier Transform (STFT), Continuous Wavelet Transform (CWT)), and LOFAR (Low Frequency Analysis and Recording) fine-line spectrum, to obtain multi-dimensional feature distributions of typical underwater noise sources. Experimental results indicate that the lake ambient noise maintains a stable wideband distribution within 10~100 Hz, with a decay slope of −9 dB/oct across the mid-to-high frequency band. Non-cavitating propeller noise is characterized by discrete harmonic line spectra; under non-cavitating conditions, the blade passing frequency (BPF) exceeds the shaft rotational frequency by 10~20 dB and dominates spectral energy. For sailing vessels, shaft unbalance and asymmetric inflow wake shift the dominant spectral component to shaft rotational frequency. The experimental data can provide reproducible benchmark references for underwater target recognition, ambient noise suppression, and the design of underwater acoustic detection.