Computation of wall pressure fluctuations and flow induced noise by large eddy simulation

2012 ◽  
Vol 131 (4) ◽  
pp. 3333-3333 ◽  
Author(s):  
Zhang Nan ◽  
Shen Hong-cui ◽  
Tian Yu-kui
Keyword(s):  
Large Eddy Simulation ◽  
Pressure Fluctuations ◽  
Wall Pressure ◽  
Eddy Simulation ◽  
Wall Pressure Fluctuations ◽  
Large Eddy ◽  
Flow Induced Noise

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.

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.

Large-Eddy Simulation of Unsteady Surface Pressure Over a LP Turbine Blade Due to Interactions of Passing Wakes and Inflexional Boundary Layer

2005 ◽  
Author(s):  
S. Sarkar ◽  
Peter R. Voke
Keyword(s):  
Large Eddy Simulation ◽  
Turbine Blade ◽  
Coherent Structures ◽  
Pressure Fluctuations ◽  
Time Dependent ◽  
Suction Surface ◽  
Eddy Simulation ◽  
Large Eddy ◽  
Grid Points ◽  
Lp Turbine

The unsteady pressure over the suction surface of a modern low-pressure (LP) turbine blade subjected to periodically passing wakes from a moving bar wake generator is described. The results presented are a part of detailed Large-Eddy Simulation (LES) following earlier experiments over the T106 profile for a Reynolds number of 1.6×105 (based on the chord and exit velocity) and the cascade pitch to chord ratio of 0.8. The present LES uses coupled simulations of cylinder for wake, providing four-dimensional inflow conditions for successor simulations of wake interactions with the blade. The three-dimensional, time-dependent, incompressible Navier-Stokes equations in fully covariant form are solved with 2.4×106 grid points for the cascade and 3.05×106 grid points for the cylinder using a symmetry-preserving finite difference scheme of second-order spatial and temporal accuracy. A separation bubble on the suction surface of the blade was found to form under the steady state condition. Pressure fluctuations of large amplitude appear on the suction surface as the wake passes over the separation region. Enhanced receptivity of perturbations associated with the inflexional velocity profile is the cause of instability and coherent vortices appear over the rear half of the suction surface by the rollup of shear layer via Kelvin-Helmholtz (K-H) mechanism. Once these vortices are formed, the steady-flow separation changes remarkably. These coherent structures embedded in the boundary amplify before breakdown while traveling downstream with a convective speed of about 37 percent of the local free-stream speed. The vortices play an important role in the generation of turbulence and thus to decide the transitional length, which becomes time-dependent. The source of the pressure fluctuations on the rear part of the suction surface is also identified as the formation of these coherent structures. When compared with experiments, it reveals that LES is worth pursuing as an understanding of the eddy motions and interactions is of vital importance for the problem.

Prediction of Pressure Fluctuation on a Vehicle by Large Eddy Simulation

2015 ◽  
Author(s):  
Yoshinobu Yamade ◽  
Chisachi Kato ◽  
Akiyoshi Iida ◽  
Shinobu Yoshimura ◽  
Keiichiro Iida
Keyword(s):  
Structural Analysis ◽  
Large Eddy Simulation ◽  
Unsteady Flow ◽  
Pressure Fluctuation ◽  
Pressure Fluctuations ◽  
Sound Fields ◽  
Eddy Simulation ◽  
Acoustical Analysis ◽  
Wide Range ◽  
Large Eddy

The objective of this study is to predict accurately interior aeroacoustics noise of a car for a wide range of frequency between 100 Hz and 4 kHz. One-way coupled simulations of computational fluid dynamics (CFD), structural analysis and acoustical analysis were performed to predict interior aeroacoustics noise. We predicted pressure fluctuations on the outer surfaces of a test car by computing unsteady flow around the car as the first step. Secondary, the predicted pressure fluctuations were fed to the subsequent structural analysis to predict vibration accelerations on the inner surfaces of the test car. Finally, acoustical analysis was performed to predict sound fields in the test car by giving vibration accelerations computed by the structural analysis as the boundary conditions. In this paper, we focus on the unsteady flow computations, which is the first step of the coupled simulations. Large Eddy Simulation (LES) was performed to predict the pressure fluctuations on the outer surfaces of the test car. We used the computational mesh composed of approximately 5 billion hexahedral grids with a spatial resolution of 1.5 mm in the streamwise and spanwise directions to resolve the dynamics of the small vortices in the turbulence boundary layer. Predicted and measured pressure fluctuation at several sampling points on the surface of the test car were compared and they matched well in a wide range of frequency up to 2 kHz.

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