Propeller acoustic measurements in atmospheric towing tank

• Published in: Ocean engineering Vol. 120; pp. 190 - 201
• Main Authors: Haimov, Henri, Gallego, Vicente, Molinelli, Enrique, Trujillo, Borja
• Format: Journal Article
• Language: English
• Published: Elsevier Ltd 01.07.2016
• Subjects: Acoustic measurement; Acoustic noise; Background noise; Experimental acoustics; Hulls; Marine; Mathematical models; Model marine propellers and hulls; Model tests; Noise; Propellant tanks; Propellers; Towing; Towing tank; CFD; ΔT; ρ; D; Kp; Noise; Model tests; M; SPL; LKp; Towing tank; CSD; SP; Model marine propellers and hulls; ENBW; PSD; HP1; OW; HP0; n; Wf; p; CAT; Experimental acoustics; BPF; Kpref
• ISSN: 0029-8018; 1873-5258
• DOI: 10.1016/j.oceaneng.2015.06.047

The study describes the implementation of experimental procedure for measuring the hydrodynamic noise generated by model scale marine propellers in atmospheric towing tank. The study is limited to non-cavitating conditions of the propeller as the experimental tank is at atmospheric pressure. The towing carriage and conditions have not been altered admitting the existence of considerable background noise. The feasibility analysis included experimental and theoretical study of the background noise at the operating conditions. Some considerations about the uncertainty of the results are also presented. The experimental equipment, set up and procedure for measuring the acoustic pressure around model ship propeller and/or hull is also described. Simultaneous measurements with various differently positioned hydrophones at multiple hydrodynamic conditions permitted to evaluate the background and propeller/hull generated acoustic field at a range of frequencies. An appropriate treatment of the recorded time series characterised the background disturbances and permitted to obtain net results with sufficient signal to noise ratio, mostly from narrowband spectral analysis. Results for the impact of the hull presence on propeller acoustic field are presented and discussed. The extrapolated results are compared informatively with full scale measurements. The research presented in this paper is a result of the Collaboration agreement on underwater acoustics between CEHIPAR and ITM and is partially funded by the European Commission project AQUO (Achieve Quieter Oceans by Shipping Noise Footprint Reduction), Seventh Framework Programme, Grant number 314227, FP7-SST-2012.1.1-1. •Measuring the noise emitted by the marine propeller is necessary for various issues.•The specifications of model experimental test setup with 4 hydrophones are presented.•Background acoustic noise sources are analysed and quantified for each case studied.•Specific ship and propeller models were tested under different conditions.•The spectral results reveal the behaviour of the propeller alone and behind the ship.