scholarly journals The suppression of hydrodynamic noise from underwater cavities by the change of back wall chamfer

2019 ◽  
Vol 283 ◽  
pp. 08007
Author(s):  
Hao Zhang ◽  
Yongwei Liu ◽  
Dejiang Shang
Keyword(s):  
Noise Suppression ◽  
Acoustic Analogy ◽  
Back Wall ◽  
Trailing Edge ◽  
Airfoil Surface ◽  
Eddy Simulation ◽  
Fluctuation Pressure ◽  
Flow Induced Noise ◽  
Hydrodynamic Noise ◽  
The Impact

When underwater vehicles are sailing, high hydrodynamic noise will be generated through the opening cavities due to the interaction of the surface and the fluids. In the paper, we had tested different forms of back wall chamfer by numerical calculation based on the method of large eddy simulation, to control the impact of the eddy and break the flow at the trailing edge of the cavity, which is with the dimension of 100mm wide, 120mm high and 100mm long. The angle and shape of the trailing edge chamfer are changed to control the flow of the cavity. We had also investigated the effect of hydrodynamic noise suppression through the simulation, which is based on the method of Lighthill’s acoustic analogy. The results show that the change of back wall chamfer can stabilize the movement of the eddies inside the cavity and reduce the fluctuation pressure at the trailing edge of the cavity. The suppression of flow-induced noise can be up to 5 dB, if the back-wall chamfer is with the airfoil surface and the angle of back wall chamfer is properly designed.

scholarly journals Numerical study of a control scheme on flow-induced cavity noise

2019 ◽  
Vol 283 ◽  
pp. 09002
Author(s):  
Lulu Liu ◽  
Jin Liu ◽  
Shijin Lyu
Keyword(s):  
Experimental Data ◽  
Cavity Length ◽  
Numerical Study ◽  
Numerical Procedure ◽  
Acoustic Analogy ◽  
Cavity Depth ◽  
Eddy Simulation ◽  
Control Scheme ◽  
Large Eddy ◽  
Flow Induced Noise

A numerical procedure for flow induced cavity noise is established in the paper. The procedure is based on large eddy simulation and FW-H acoustic analogy. The computational scheme is validated by comparing with experimental data. The change of flow induced noise along with cavity length, cavity depth and velocity is studied. A noise control scheme, which includes upright grille and oblique grille, is designed for reducing the flow-induced cavity noise. It turns out that the oblique grille shows superiority in the reduction of cavity noise by modifying the flow structure of the sheat layer.

Flow-Induced Noise Simulation Based on LES/Lighthill Hybrid Method

2014 ◽  
Vol 614 ◽  
pp. 428-431 ◽  
Author(s):  
Yong Ou Zhang ◽  
Tao Zhang ◽  
Tian Yun Li
Keyword(s):  
Hybrid Method ◽  
Aerodynamic Noise ◽  
Acoustic Analogy ◽  
Eddy Simulation ◽  
Noise Simulation ◽  
Simulation Based ◽  
Hybrid Numerical Method ◽  
Flow Induced Noise ◽  
Flow Through ◽  
Simulation Results

A hybrid numerical method of combining Large Eddy Simulation (LES) and Lighthill’s acoustic analogy theory is utilized to simulate the flow-induced noise at low Mach numbers. The aerodynamic noise generated by flow through a cavity, which is similar to a valve, is simulated and the results are validated by comparing with the open literature. In the simulation, the turbulent flow is computed with LES. After this, the flow field simulation results are used to compute the flow-induced noise with Lighthill’s acoustic analogy theory based on the commercial software ACTRAN. Finally, the simulation results of the flow-induced noise, including the sound pressure level and the peak frequencies, are analyzed and compared with experimental data. It is validated that the hybrid method of combining LES and Lighthill’s acoustic analogy theory used in this paper is feasible and reliable in engineering applications.

scholarly journals Flow-induced noise simulation using detached eddy simulation and the finite element acoustic analogy method

2016 ◽  
Vol 8 (7) ◽  
pp. 168781401665568 ◽  
Author(s):  
Kai Liu ◽  
Shaoqi Zhou ◽  
Xuexin Li ◽  
Xiumei Shu ◽  
Lianhuan Guo ◽  
...  
Keyword(s):  
Finite Element ◽  
Detached Eddy Simulation ◽  
Acoustic Analogy ◽  
Analogy Method ◽  
Eddy Simulation ◽  
Noise Simulation ◽  
Flow Induced Noise

Impact of the trailing edge shape of a downstream dummy vehicle on train aerodynamics subjected to crosswind

2020 ◽  
pp. 095440972091503 ◽  
Author(s):  
Xiaoshuai Huo ◽  
Tanghong Liu ◽  
Miao Yu ◽  
Zhengwei Chen ◽  
Zijian Guo ◽  
...  
Keyword(s):  
Wind Tunnel ◽  
Detached Eddy Simulation ◽  
Trailing Edge ◽  
Wind Tunnel Tests ◽  
Eddy Simulation ◽  
Pressure Distributions ◽  
Delayed Detached Eddy Simulation ◽  
Yaw Angle ◽  
Train Aerodynamics ◽  
The Impact

Wind tunnel tests for trains under large yaw angles are usually limited due to the width of the wind tunnel. Therefore, the leading car and a downstream dummy vehicle model are often employed instead of a real train, but there are no clear regulations regarding the shape of the end of the dummy vehicle. This paper studied the impact of the trailing edge shape of the downstream dummy vehicle on train aerodynamics subjected to crosswind based on the shear-stress-transport k-ω turbulence model of the delayed detached eddy simulation. Three types of end shapes, namely the rectangular end shape, the arc end shape, and the streamlined end shape were chosen for comparison, and the simulation results of the three-car-group train were selected as the benchmark. First, the reliability of the numerical method was validated by wind tunnel tests. Then, the aerodynamic coefficients under yaw angles of 0°–60° and the surface pressure distributions and flow structures around the train under the yaw angle of 60° of the head cars with different end shapes were compared and analyzed.

scholarly journals Effect of Tailing-Edge Thickness on Aerodynamic Noise for Wind Turbine Airfoil

Energies ◽  
2019 ◽  
Vol 12 (2) ◽  
pp. 270 ◽  
Author(s):  
Xinkai Li ◽  
Ke Yang ◽  
Hao Hu ◽  
Xiaodong Wang ◽  
Shun Kang
Keyword(s):  
Wind Turbine ◽  
Sound Pressure ◽  
Low Frequency ◽  
Experimental Results ◽  
Aerodynamic Noise ◽  
Calculation Methods ◽  
Trailing Edge ◽  
Eddy Simulation ◽  
Wind Turbine Airfoil ◽  
The Impact

The influence of wind turbine airfoil trailing edge thickness on aerodynamics and aerodynamic noise characteristics was studied using the computational fluid dynamics (CFD)/ Ffowcs Williams–Hawkings (FW–H) method in the present work. First, the airfoil of a DU97-W-300-flatback airfoil was chosen as the research object, and numerical method validation was performed. Three kinds of turbulence calculation methods (unsteady Reynolds average Navier-Stokes (URANS), detached eddy simulation (DES), and large eddy simulation (LES)) were investigated in detail, and three sets of grid scales were used to study the impact of the airfoil on the aerodynamic noise. Secondly, the airfoil trailing edge thickness was changed, and the impact of trailing edge thickness on aerodynamics and aerodynamic noise was investigated. Results show that three kinds of turbulence calculation methods yield the same sound pressure frequency, and the magnitude of the sound pressure level (SPL) corresponding to the mean frequency is almost the same. The calculation of the SPL of the peak value and the experimental results can match well with each other, but the calculated core frequency is slightly lower than the experimental frequency. The results of URANS and DES are closer to each other with a changing trend of SPL, and the consequences of the DES calculation are closer to the experimental results. From the comparison of two airfoils, the blunt trailing edge (BTE) airfoil has higher lift and drag coefficients than the original airfoil. The basic frequency of lift coefficients of the BTE airfoil is less than that of the original airfoil. It is demonstrated that the trailing vortex shedding frequency of the original airfoil is higher than that of the BTE airfoil. At a small angle of attack (AOA), the distribution of SPL for the original airfoil exhibits low frequency characteristics, while, at high AOA, the wide frequency characteristic is presented. For the BTE airfoil, the distribution of SPL exhibits low frequency characteristics for the range of the AOA. The maximum AOA of SPL is 4° and the minimum AOA of SPL is 15°, while, for the original airfoil, the maximum AOA of SPL is 19°, and the minimum AOA is 8°. For most AOAs, the SPL of the BTE airfoil is larger than that of the original airfoil.

The Hydrodynamic Noise Suppression of a Scaled Submarine Model by Trailing-Edge Serrations

2021 ◽  
Author(s):  
Yalin Li ◽  
Junxiang Ye ◽  
Juyi Wu ◽  
Tao Zhang ◽  
Zenghui Zhang ◽  
...  
Keyword(s):  
Noise Suppression ◽  
Trailing Edge ◽  
Hydrodynamic Noise ◽  
Trailing Edge Serrations
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