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.

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.

Study on the Simulation Method of Compressor Aerodynamic Noise Based on CFD and IBEM

2016 ◽  
Author(s):  
Liu Chen ◽  
Cao Yipeng ◽  
Sun Wenjian ◽  
Zhang Wenping ◽  
Ming Pingjian ◽  
...  
Keyword(s):  
Boundary Element Method ◽  
Boundary Element ◽  
Fluid Dynamic ◽  
Simulation Method ◽  
Aerodynamic Noise ◽  
Noise Sources ◽  
Indirect Boundary Element Method ◽  
Unsteady Viscous Flow ◽  
Radiation Noise ◽  
Element Method

Turbocharger compressor aerodynamic noise has been one of the major noise sources of diesel engine. It is necessary to study the characteristics of turbocharger fluid flow and radiation noise for its effective noise control. In this paper, a new for predicting compressor aerodynamic noise is presented, which combined the computational fluid dynamic (CFD) and indirect boundary element method (IBEM). The unsteady viscous flow in compressor was simulated based on the finite volume method. In addition, the periodic pressure fluctuation of the rotor inlet and blades were used to compressor radiation noise field simulation by indirect boundary element method. In order to prove the feasibility of numerical simulation, the acoustics experimental device for compressor aerodynamic noise experiment was built and the sound pressure of turbocharger were tested. The trend of simulation results and amplitude level in blade passing frequency (BPF) coincide with the experiment results. It indicates that the coupling method is more effective and accurate in turbocharger noise prediction.

Inverse Identification of Heat Boundary Conditions for 2-D Anisotropic Coating Structures

2011 ◽  
Vol 130-134 ◽  
pp. 1825-1828
Author(s):  
Huan Lin Zhou ◽  
Hu Sha Han ◽  
Chang Zheng Cheng ◽  
Zhong Rong Niu
Keyword(s):  
Boundary Element Method ◽  
Singular Value Decomposition ◽  
Boundary Conditions ◽  
Boundary Element ◽  
Singular Integrals ◽  
Singular Value ◽  
Thin Body ◽  
Ill Posed ◽  
Value Decomposition ◽  
Element Method

The singular value decomposition is employed to identify heat boundary conditions for 2-D anisotropic coating structures. The boundary element method is applied to analyzing the model. The nearly singular integrals in the boundary element method for thin body problems are dealt with by the analytical integral formulas. The ill-posed system is treated by the truncated singular value decomposition technique. Numerical example demonstrates the effectiveness and accuracy of the present algorithm.

A DIRECT MIXED-BODY BOUNDARY ELEMENT METHOD FOR MUFFLERS WITH INTERNAL THIN COMPONENTS COVERED BY LINING AND A PERFORATED PANEL

2007 ◽  
Vol 15 (01) ◽  
pp. 145-157 ◽  
Author(s):  
K. L. PAN ◽  
C. I. CHU ◽  
T. W. WU
Keyword(s):  
Boundary Element Method ◽  
Boundary Element ◽  
Experimental Comparison ◽  
Thin Body ◽  
Wall Surface ◽  
Interior Wall ◽  
Lining Material ◽  
Body Boundary ◽  
Impedance Modeling ◽  
Element Method

Thin components, such as baffles, extended inlet/outlet tubes, and internal connecting tubes, are commonly used in reactive mufflers for cancelation of sound at particular frequency peaks. To provide additional absorption effects at higher frequencies, porous sound absorbing materials may be used on the muffler interior wall surface or on any internal thin components. If the sound absorbing material is backed by a rigid surface, it is usually modeled by the local normal impedance approach. The local impedance modeling on the interior wall surface is straightforward and has been extensively used in the boundary element method, in which the boundary surface is just moved forward to the contact surface between the lining and air. On the other hand, the local impedance modeling on any internal thin components is relatively rare. This paper first presents a direct mixed-body boundary element formulation for a thin body covered by local impedance on either side or both sides of the thin body. The local impedance can be from the lining material itself, or from the lining material plus a protective perforated metal cover. Several test cases with experimental comparison are presented in this paper.

Three-Dimensional Transient Advective Diffusion by Boundary Element Method using Direct Time Integral of the Fundamental Solution

1990 ◽  
Vol 212 ◽  
Author(s):  
Ryuji Kawamura ◽  
Akira Isono
Keyword(s):  
Boundary Element Method ◽  
Fundamental Solution ◽  
Boundary Element ◽  
Time Integration ◽  
Three Dimensional ◽  
Boundary Integral ◽  
Fluid Analysis ◽  
Chemically Reacting ◽  
Advective Diffusion ◽  
Element Method

ABSTRACTThe advective diffusion analyses have been applied to many fields of science and engineering, such as dispersion for chemically reacting(first-order reaction) substance, thermal transport in fluid, analysis of electromagnetic field caused by a moving magnet. electron transport in semiconductors, underground migration of radioactive waste, and so on. The boundary element method (BEM) has been developed extensively for the last decade to solve these transient advective diffusion equation. The time integrations of the fundamental solution in the boundary integral equation, however, make the BEM application to advective diffusion problems difficult. Therefore, the time integration has been approximated in the past relevant publications. This paper describes the BEM in which the time integration is done analytically, and technique is demonstrated with several examples. Good results have been obtained in the example calculations, where comparisons are made with the results from other numerical codes.

Failure Analysis of Anisotropic Plates by the Boundary Element Method

2014 ◽  
Vol 30 (6) ◽  
pp. 561-570 ◽  
Author(s):  
A. Sahli ◽  
S. Boufeldja ◽  
S. Kebdani ◽  
O. Rahmani
Keyword(s):  
Boundary Element Method ◽  
Boundary Element ◽  
Time Integration ◽  
Fundamental Solutions ◽  
Thin Plates ◽  
Anisotropic Plates ◽  
Second Derivatives ◽  
Dynamic Formulation ◽  
Derivatives Of ◽  
Element Method

AbstractThis paper presents a dynamic formulation of the boundary element method for stress and failure criterion analyses of anisotropic thin plates. The elastostatic fundamental solutions are used in the formulations and inertia terms are treated as body forces. The radial integration method (RIM) is used to obtain a boundary element formulationithout any domain integral for general anisotropic plate problems. In the RIM, the augmented thin plate spline is used as the approximation function. A formulation for transient analysis is implemented. The time integration is carried out using the Houbolt method. Integral equations for the second derivatives of deflection are developed and all derivatives of fundamental solutions are computed analytically. Only the boundary is discretized in the formulation. Numerical results show good agreement with results available in literature as well as finite element results.

Sign in / Sign up

Export Citation Format

Share Document