Non-Cavitating Noise Control of a Marine Propeller by Optimizing Number and Pitch of Blades

Abstract

The Propeller is a vital component which is delicate for the safe operation of a ship at sea. The propeller noise is very much significant to warship designers and military strategists for many years. By using large eddy simulation (LES) it is possible to simulate the sound radiation of turbulent flows effectively, providing access to resolve turbulent scales at higher accuracy. The main aim of this paper is to study and identify a propeller which is producing less noise. The present paper deals with the prediction of the unsteady non-cavitating marine propeller noise of 5, 6, and 7 blades with +10° pitch, +5° pitch, existing pitch, and −5° pitch, −10° pitch at rotational speed 840 rpm and vehicle speeds of 7.62 m/s, using eddy viscosity model of large eddy simulation (LES) available in computational fluid dynamics fluent software and using Ffowcs Williams–Hawkings (FW-H) formulation. Here solver is chosen as pressure-based, unsteady formulation of second-order implicit. Finite volume method is used to predict the noise in time-domain acoustic analogy. Sound pressure levels are predicted at different receiver positions. The receiver position is 1 m distance in radial direction to the propeller. From this numerical study on these propellers, it is found that the propeller of 6 blades with +5° pitch generates least noise. Finalized the propeller which is producing low noise as well as which generates required Thrust and Torque by changing the diameter of the propeller. Finally, obtain the noise reduction of 9.4 dB with the new redesigned propeller when compared with the baseline propeller for the same thrust and torque.