Spectral analysis of the underwater acoustic noise radiated by ships with controllable pitch propellers

Abstract

This paper presents spectral analyses of the underwater noise radiated by ships equipped with controllable pitch propellers. The noise measurements were performed at sea for three different ship’s types. Each ship passage was characterized by a specific combination of propeller rotational speed and propeller pitch, allowing to investigate the variations of the radiated noise spectrum at different settings of the pitch-RPM combination law. Neglecting the low-frequency contributions, the focus is on the analysis of the broadband patterns in the range 100 Hz to 4 kHz A parameterization derived from a basic spectral pattern is adopted: the noise spectrum shape is approximated with a flat level magnitude up to a reasonable frequency followed by a logarithmic decay. An investigation of the relationship between the considered parameters and the actual ship condition is proposed along with a comparison with the predictions provided by classic Ross and Whales-Heitmeyer ship noise models

Underwater Wireless Sensor Networks: A Survey on Enabling Technologies, Localization Protocols, and Internet of Underwater Things

“…Several works have focused on publishing data set and spectral analysis to investigate the impact on the acoustic spectrum. Authors in [59] aim the exploitation of controllable pitch propeller settings and the inherent radiated noise dependencies on the spectral analysis of underwater noise generated by ships. Although narrow-band contributions, broadband noise analysis is investigated in the frequency band ranging from 100 Hz to 4 kHz.…”

Review of Research Results Concerning the Modelling of Shipping Noise

“…There are almost nine kinds of ship source level models published so far [14][15][16][17][22][23][24][25][26][27], which can be roughly categorised into two groups, according to modelling mechanism. One model tries to establish the fitting relationship between SL and ship speed, ship length (or tonnage) and frequency from the statistical law of amount of measured data, and the others emphasise the noise-generated mechanism, namely the superposition of mechanical noise, propeller cavitation noise and non-cavitation noise, as illustrated in Table 2.…”

“…Their specific expressions, applicable conditions and the relations between these models are systematically sorted and summarised here. It should be noted that the 'three-parameter' model [25,26] is not included here as it mainly deals with the adjustable pitch propeller used in a portion of current merchant ships. The basic relationships of the other SL models are shown in Fig.…”

Modeling and Simulation of Underwater Acoustic Communication Systems

“…In (13) it is possible to see that the coarse compensation of DSF produces an undesired residual frequency ε. This residual frequency vanishes only ifâ = a; however, it is extremely difficult to achieve a perfect estimation of DSF in practical situations.…”

“…Indeed, acoustic signals are low-frequency mechanical waves, which are much less attenuated when propagating in an underwater environment. On the other hand, employing these signals is a very complicated task, since the underwater acoustic (UWA) noise is intense [11], [12], [13] and UWA channels feature strong time variations [2]. Moreover, UWA communication is severely degraded by Doppler effects [3] due to the low propagation speed of the acoustic waves and the ubiquitous relative motion between transmitter and receiver.…”