Shahrood University of Technology Journal of Solid and Fluid Mechanics 2251-9475 13 3 2023 07 23 Numerical investigation of the blades number effect on the bipolar noise radiation level caused by the high skew propeller Numerical investigation of the blades number effect on the bipolar noise radiation level caused by the high skew propeller 143 158 2910 10.22044/jsfm.2023.12470.3673 FA Ehsan Yari Assist. Prof., Malek-Ashtar university of technology/Mechanical engineering faculty, Tehran, Iran Mohammad Reza Nateghi MSc, Malek-Ashtar university of technology/Mechanical engineering faculty, Tehran, Iran Journal Article 2022 12 03 The hydro-acoustic behavior and noise of marine propellers, especially in underwater vessels and submarines is of great importance. The main purpose of this article, is numerical modeling of the hydrodynamic noise of a high skew propeller sample from MAU marine standard series using computational fluid dynamics method with the help of Ansys-Fluent software under open water conditions. In the numerical simulation, the DES turbulence model was used, which is a good model for small vortices modeling near the wall. In order to validate the hydrodynamic and hydr-oacoustic results, the available data from the DTMB4119 benchmark propeller has been used. Comparison of the sound pressure level obtained for the DTMB4119 propeller in the present work and the available data from the reference shows a good compliance at frequencies higher than 20 Hz, but at frequencies lower than 20 Hz, about 20% error is observed. Based on the obtained results, with the increase in the number of propeller blades, the amount of vortex density around the blades decreases. The increase in the number of propeller blades has caused an increase in the average level of radiation noise in receivers at the axial direction. Increasing the number of propeller blades from 2 to a maximum of 7 blades has been able to reduce the radiated noise level in the axial direction by 15 decibels. In the radial direction, except the two-bladed propeller, the dipole radiated noises caused by the 3-7-bladed propellers have similar fluctuations. The hydro-acoustic behavior and noise of marine propellers, especially in underwater vessels and submarines is of great importance. The main purpose of this article, is numerical modeling of the hydrodynamic noise of a high skew propeller sample from MAU marine standard series using computational fluid dynamics method with the help of Ansys-Fluent software under open water conditions. In the numerical simulation, the DES turbulence model was used, which is a good model for small vortices modeling near the wall. In order to validate the hydrodynamic and hydr-oacoustic results, the available data from the DTMB4119 benchmark propeller has been used. Comparison of the sound pressure level obtained for the DTMB4119 propeller in the present work and the available data from the reference shows a good compliance at frequencies higher than 20 Hz, but at frequencies lower than 20 Hz, about 20% error is observed. Based on the obtained results, with the increase in the number of propeller blades, the amount of vortex density around the blades decreases. The increase in the number of propeller blades has caused an increase in the average level of radiation noise in receivers at the axial direction. Increasing the number of propeller blades from 2 to a maximum of 7 blades has been able to reduce the radiated noise level in the axial direction by 15 decibels. In the radial direction, except the two-bladed propeller, the dipole radiated noises caused by the 3-7-bladed propellers have similar fluctuations. https://jsfm.shahroodut.ac.ir/article_2910_f48ad04deb7dd4a16823dcd85958e4fd.pdf