342 Visualization of Sound Pressure with Boundary Element Method

2007 ◽  
Vol 2007 (0) ◽  
pp. _342-1_-_342-6_
Author(s):  
Keisuke IKEDA ◽  
Takuya YOSHIMURA
Keyword(s):  
Boundary Element Method ◽  
Boundary Element ◽  
Sound Pressure ◽  
Element Method

scholarly journals Acoustic Improvements of Aircraft Headrests Based on Electrospun Mats Evaluated Through Boundary Element Method

2020 ◽  
Vol 10 (16) ◽  
pp. 5712
Author(s):  
Venanzio Giannella ◽  
Francesco Branda ◽  
Jessica Passaro ◽  
Giuseppe Petrone ◽  
Mattia Barbarino ◽  
...  
Keyword(s):  
Boundary Element Method ◽  
Boundary Element ◽  
Sound Pressure ◽  
Pressure Level ◽  
Cabin Noise ◽  
Acoustic Load ◽  
Acoustic Comfort ◽  
Passive Noise ◽  
The Impact ◽  
Element Method

This work illustrates the development of passive noise control (PNC) improvements of aircraft headrests to enhance the acoustic comfort for passengers. Two PNC improvements were studied with the aim of reducing the noise perceived by passengers during flight. Two headrest configurations, with and without the lateral caps, and two different materials, a traditional foam and an innovative Silica/Polyvinylpyrrolidone (PVP) woven non-woven mat, were considered, and compared in terms of sound pressure level (SPL) perceived by passengers. Boundary element method (BEM) models were built up to evaluate the acoustic performances of different headrest configurations, varying in terms of shape and textile. A spherical distribution of monopole sources surrounding the headrests was considered as acoustic load, in such a way as to recreate a diffuse acoustic field simulating the cabin noise perceived by passengers during cruise conditions. The impact of the two PNC improvements was analyzed to envisage some general guidelines useful to design advanced headrests from the acoustic viewpoint.

Prediction of sound pressure in the far field using the inverse boundary element method

2010 ◽  
Vol 58 (1) ◽  
pp. 74 ◽  
Author(s):  
D. W. Herrin ◽  
J. Liu ◽  
F. Martinus ◽  
D. J. Kato ◽  
S. Cheah
Keyword(s):  
Boundary Element Method ◽  
Boundary Element ◽  
Sound Pressure ◽  
Far Field ◽  
Inverse Boundary ◽  
Element Method

scholarly journals Computation of Aerodynamic Noise Radiated from Ducted Tail Rotor Using Boundary Element Method

2017 ◽  
Vol 2017 ◽  
pp. 1-13 ◽  
Author(s):  
Yunpeng Ma ◽  
Mingxu Yi ◽  
Lifeng Wang ◽  
Jun Huang
Keyword(s):  
Boundary Element Method ◽  
Boundary Element ◽  
Sound Pressure ◽  
Time Integration ◽  
Aerodynamic Noise ◽  
Thin Body ◽  
Acoustic Analogy ◽  
Source Information ◽  
Scattering Effect ◽  
Element Method

A detailed aerodynamic performance of a ducted tail rotor in hover has been numerically studied using CFD technique. The general governing equations of turbulent flow around ducted tail rotor are given and directly solved by using finite volume discretization and Runge-Kutta time integration. The calculations of the lift characteristics of the ducted tail rotor can be obtained. In order to predict the aerodynamic noise, a hybrid method combining computational aeroacoustic with boundary element method (BEM) has been proposed. The computational steps include the following: firstly, the unsteady flow around rotor is calculated using the CFD method to get the noise source information; secondly, the radiate sound pressure is calculated using the acoustic analogy Curle equation in the frequency domain; lastly, the scattering effect of the duct wall on the propagation of the sound wave is presented using an acoustic thin-body BEM. The aerodynamic results and the calculated sound pressure levels are compared with the known technique for validation. The sound pressure directivity and scattering effect are shown to demonstrate the validity and applicability of the method.

Acoustic characteristic analysis of power transformers in urban communities based on a combined finite and boundary element method

2019 ◽  
Vol 29 (2) ◽  
pp. 208-220
Author(s):  
Liming Ying ◽  
Donghui Wang ◽  
Guodong Wang ◽  
Wenyi Wang
Keyword(s):  
Boundary Element Method ◽  
Boundary Element ◽  
Acoustic Field ◽  
Sound Pressure ◽  
Power Transformer ◽  
Power Transformers ◽  
Spatial Sound ◽  
Sound Pressure Levels ◽  
External Acoustic Field ◽  
Element Method

Power transformers in substations are common sources of noise in residential areas of neighbourhoods. A quantified and visualized analysis of the power transformer acoustic characteristics is a prerequisite for the suppression of audible noise from the corresponding substation. In this study, based on a combined finite and boundary element method, a full-sized 3D power transformer multiphysics coupling model, which is aimed at realizing high accuracy and improving the computational efficiency, was developed. After validation of the numerical method using comparative tests, profile analyses in the near-field and far-field in the extended planes and three-dimensional areas of a power transformer were conducted to characterize the external acoustic field. The calculation results included the distribution of the spatial sound pressure levels of the power transformer at multiple levels in the frequency domain. These spatial sound pressure levels can be used to guide the efficient measurement of the external acoustic field of a power transformer and the soundscape planning around a substation, and the differentiated design of the sound absorption structure inside a substation.

Investigation of Ship Structural Vibration and Underwater Radiation Noise

2003 ◽  
Vol 47 (04) ◽  
pp. 275-289
Author(s):  
Chun-Ping Zou ◽  
Duan-Shi Chen ◽  
Hong-Xing Hua
Keyword(s):  
Finite Element ◽  
Boundary Element Method ◽  
Boundary Element ◽  
Sound Pressure ◽  
Structural Vibration ◽  
Design Stage ◽  
Dominant Source ◽  
Sound Pressure Levels ◽  
Radiation Noise ◽  
Element Method

Underwater radiation noise is a very important factor for most ships, such as fishing boats, warships, and so forth. The magnitude of its energy depends on the vibration of the hull in contact with water. The vibration of the hull caused by the power plant, while the vessel is cruising, is the dominant source of underwater radiation noise, which is the subject of our investigation. In this paper, the coupled finite element/boundary element method is used to investigate ship structural vibration and underwater radiation noise. The finite element method (FEM) is employed to analyze modes and vibration responses of an entire ship for different kinds of excitations in consideration of fluid-structure interaction. The boundary element method (BEM) is used to analyze the underwater radiation noise. A FEM model is first constructed by using 30 geometric parameters and five kinds of finite elements. Then, the reduced matrix method is used to eliminate the local modes in order to obtain the overall bending and torsional modes of the ship. Last, vibration displacements of the hull are treated as the velocity boundary condition of BEM to calculate underwater radiation noise. Numerical results show thatthe calculated sound-pressure levels of underwater radiation noise are in a good agreement with experimentally measured results;although the vibration isolator is used, the propulsion diesel engine is the dominant source of the underwater radiation noise among all machines in the engine room and the maximum sound-pressure levels increase as the sailing speed of the ship increases;the underwater radiation noise of the ship with gearbox excitation is greater than that of the ship with diesel generator set excitation, which should be noticed by the ship designers during the design stage.

Using the Inverse Boundary Element Method to Predict Sound Pressure in the Far Field

2008 ◽  
Author(s):  
D. W. Herrin ◽  
J. Liu ◽  
J. Han ◽  
S. Cheah ◽  
D. J. Kato
Keyword(s):  
Boundary Element Method ◽  
Boundary Element ◽  
Sound Pressure ◽  
Near Field ◽  
Numerical Procedure ◽  
Far Field ◽  
Pressure Measurements ◽  
Inverse Boundary ◽  
Field Sound ◽  
Element Method

The inverse boundary element method (BEM) is a numerical procedure whereby sound pressure measurements in the near field are used to predict the vibration on the vibrating surface. After the vibration (or particle velocity for an opening) is determined, the sound pressure in the far field can be predicted using a forward BEM analysis. This paper will examine a particular example where the far field sound pressure was predicted for a generator set. The results indicate that the vibration predicted by the inverse BEM can be used to accurately predict the sound pressure as far away as 7 meters from the source.

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