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.

scholarly journals Experimental/Numerical Acoustic Assessment of Aircraft Seat Headrests Based on Electrospun Mats

2021 ◽  
Vol 11 (14) ◽  
pp. 6400
Author(s):  
Venanzio Giannella ◽  
Claudio Colangeli ◽  
Jacques Cuenca ◽  
Roberto Citarella ◽  
Mattia Barbarino
Keyword(s):  
Boundary Element Method ◽  
Experimental Validation ◽  
Sound Pressure ◽  
Pressure Level ◽  
Parallel Simulations ◽  
Aircraft Cabin ◽  
Acoustic Comfort ◽  
Set Up ◽  
Passenger Aircraft ◽  
Passive Noise

The work proposes a methodology for the assessment of the performances of Passive Noise Control (PNC) for passenger aircraft headrests with the aim of enhancing acoustic comfort. Two PNC improvements of headrests were designed to reduce the Sound Pressure Level (SPL) at the passengers’ ears in an aircraft cabin during flight; the first was based on the optimization of the headrest shape, whereas the second consisted of partially or fully covering the headrest surface with a new highly sound-absorbing nanofibrous textile. An experimental validation campaign was conducted in a semi-anechoic chamber. A dummy headrest was assembled in different configurations of shape and materials to assess the acoustic performances associated to each set up. In parallel, simulations based on the Boundary Element Method (BEM) were performed for each configuration and an acceptable correlation between experimental and numerical results was obtained. Based on these findings, general guidelines were proposed for the acoustical design of advanced headrests.

scholarly journals Numerical Modeling of the Wave-Plate-Current Interaction by the Boundary Element Method

Fluids ◽  
2021 ◽  
Vol 6 (12) ◽  
pp. 435
Author(s):  
Hasna Akarni ◽  
Laila El Aarabi ◽  
Laila Mouakkir ◽  
Soumia Mordane
Keyword(s):  
Boundary Element Method ◽  
Boundary Element ◽  
Numerical Study ◽  
Analytical Data ◽  
Geometrical Parameters ◽  
Free Surface Elevation ◽  
Uniform Current ◽  
Current Interaction ◽  
The Impact ◽  
Element Method

The aim of this work is to propose a numerical study of the interaction of a wave-horizontal plate fixed and completely immersed in a flat-bottomed tank with a uniform current flowing in the same direction as the incident wave. We investigate in particular the effect of the plate at minimizing the impact of the wave on the coast of beaches by studying the free surface elevation and the reflection coefficient, as well as the influence of the various geometrical parameters on the latter, taking into account the presence of the current. The numerical method used in this study is the boundary element method (BEM), and the results obtained will be confronted with experimental and analytical data existing in the literature.

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

A Study on the Effect of Different Median Barrier Shapes in Presence of Single or Parallel Noise Screens

2011 ◽  
Vol 383-390 ◽  
pp. 5432-5437
Author(s):  
M.R. Monazzam ◽  
Samaneh M.B. Fard
Keyword(s):  
Boundary Element Method ◽  
Boundary Element ◽  
Insertion Loss ◽  
Noise Pollution ◽  
Noise Barriers ◽  
Negative Effect ◽  
Roadside Barrier ◽  
The Impact ◽  
Mega Cities ◽  
Element Method

In most mega cities roadside barriers are used to protect receivers from noise pollution during recent years. Median noise barriers, like roadside noise barriers, can be employed to reduce the impact of traffic on roadside communities. In this study, a 2D boundary element method (BEM) is used to predict the insertion loss of different barrier models. It was shown that the performance of a median barrier along with a roadside barrier is affected if another road side barrier will be erected. However, it is possible to apply some new barrier designs to decline the negative effect of the extra roadside barrier. The best shape for inclined median barriers when erected inside parallel barriers was seen to be the tilted designed with 10 degrees slope.

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.

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