Numerical prediction of flow noise levels on towed sonar array

2020 ◽  
pp. 147509022096192
Author(s):  
K Karthik ◽  
S Jeyakumar ◽  
J Sarathkumar Sebastin
Keyword(s):  
Pressure Fluctuations ◽  
Wall Pressure ◽  
Noise Levels ◽  
Simulation Methodology ◽  
Flow Noise ◽  
Eddy Simulation ◽  
Wall Pressure Fluctuations ◽  
Large Eddy ◽  
Speed Range ◽  
Towed Array

Flow noise originating in the turbulent boundary layer (TBL) often severely limits the performance of towed sonar array. Therefore, it is necessary to predict this noise for the design of an efficient towed array. This paper presents large eddy simulation methodology to establish the TBL properties and wall pressure fluctuations on a 12 m long towed array with length to diameter ratio of 1200 in the operating tow speed range of 2 to 5 knots in water. The computed flow noise levels are compared with experimental measurements available in the literature successfully. The effectiveness of scaling the flow noise spectra with the diameter and tow speed is discussed, and non-dimensional wall pressure spectra presented with respect to non-dimensional frequency. The overall sound pressure levels are also compared with experimental data that show good accuracy achieved by the proposed numerical methodology.

scholarly journals Numerical Prediction of Wall Pressure Fluctuations in a Turbulent Boundary Layer on a Cylinder in Axial Flow

2019 ◽  
Vol 9 (1S4) ◽  
pp. 625-628
Keyword(s):  
Boundary Layer ◽  
Turbulent Boundary Layer ◽  
Pressure Fluctuations ◽  
Axial Flow ◽  
Wall Pressure ◽  
Flow Noise ◽  
Eddy Simulation ◽  
Wall Pressure Fluctuations ◽  
Large Eddy ◽  
Long Cylinder

Flow noise originating in the turbulent boundary layer (TBL) often severely limits the performance of towed sonar cylinder and therefore it is necessary to predict this noise for the design of efficient towed cylinder. This paper presents large eddy simulation methodology to establish the TBL properties and wall pressure fluctuations on a 3 m long cylinder with length to diameter ratio of 315 in the operating speed of 11.4 m/s in air. The computed flow induced sound is compared with experimental measurement available in the literature successfully. The effectiveness of scaling the flow noise spectra with diameter and tow speed is discussed and non-dimensional wall pressure spectra presented with respect to non-dimensional frequency. The overall sound pressure levels are also compared with experimental data that show good accuracy achieved by the proposed numerical methodology.

Numerical Simulation of Unsteady Flow and Flow Induced Sound of Airfoil and Wing/Plate Junction by LES and FW-H Acoustic Analogy

2013 ◽  
Vol 444-445 ◽  
pp. 479-485
Author(s):  
Nan Zhang ◽  
Shi Jin Lv ◽  
Hua Xie ◽  
Sheng Li Zhang
Keyword(s):  
Numerical Simulation ◽  
Large Eddy Simulation ◽  
Unsteady Flow ◽  
Pressure Fluctuations ◽  
Water Channel ◽  
Wall Pressure ◽  
Acoustic Analogy ◽  
Eddy Simulation ◽  
Wall Pressure Fluctuations ◽  
Large Eddy

Numerical simulation of unsteady flow and flow-induced sound of an airfoil and a wing/plate junction are performed in the paper by large eddy simulation (LES) and FW-H acoustic analogy. The vortical flows around a NACA0015 airfoil at two angles of attack (0°and 8°) are simulated and analyzed by vortex identification. Simultaneously, the wall pressure fluctuations of the airfoil are computed. At two angles of attack, the flow induced sound of the airfoil is predicted. The computed power spectra agree well with experimental measurements. So the capability of large eddy simulation in predicting unsteady flow and flow induced sound is validated. Subsequently, the horse-shoe vortex around a wing/plate junction in water is computed. Furthermore, the calculations of wall pressure fluctuations and flow induced sound of the junction model at three velocities are accomplished. The predicted results are compared favorably with measured data in large circulation water channel. So the numerical approach for flow induced sound of wing/plate junction in water is validated. It shows that the numerical simulation method in the paper is credible.

The Quantification of Internal Noise Levels and Wall Pressure Spectra in Industrial Gas Pipelines

1991 ◽  
Author(s):  
M. P. Norton ◽  
A. Pruiti
Keyword(s):  
Prediction Models ◽  
Transmission Loss ◽  
Pressure Fluctuations ◽  
Internal Noise ◽  
Wall Pressure ◽  
Gas Pipelines ◽  
Noise Levels ◽  
Empirical Prediction ◽  
Wall Pressure Fluctuations ◽  
Semi Empirical

Abstract This paper addresses the issue of quantifying the internal noise levels/wall pressure fluctuations in industrial gas pipelines. This quantification of internal noise levels/wall pressure fluctuations allows for external noise radiation from pipelines to be specified in absolute levels via appropriate noise prediction models. Semi-empirical prediction models based upon (i) estimated vibration levels and radiation ratios, (ii) semi-empirical transmission loss models, and (iii) statistical energy analysis models have already been reported on by Norton and Pruiti 1,3 and are not reported on here.

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