Sound Attenuation in Elliptic Mufflers Using a Regular Perturbation Method
نویسندگان
چکیده
The study of sound attenuation in an elliptical chamber involves the solution of the Helmholtz equation in elliptic coordinate systems. The Eigen solutions for such problems involve the Mathieu and the modified Mathieu functions. The computation of such functions poses considerable challenge. An alternative method to solve such problems had been proposed in this paper. The elliptical cross-section of the muffler has been treated as a perturbed circle, enabling the use of a regular perturbation approach to solve the wave equation. The Eigen vectors of the perturbed system has been approximated by a series summation of the unperturbed Eigen solutions. The acoustic pressure in the elliptical duct has been derived from the perturbed Eigen vectors by using the Green’s function approach.
منابع مشابه
Development and Validation of Sound Transmission Loss Measurement System for Measuring Muffler Performance
Muffler is a part of the vehicle exhaust system that absorb or reflect sound waves to reduce exhaust noise. One of the most important determinants of a muffler performance is the amount of attenuation that has on its input wave; this parameter is known as sound transmission loss. Four - mic standard test is one way to determine this parameter which is used in this paper. In this study, a test d...
متن کاملAnalytic Solution for Hypersonic Flow Past a Slender Elliptic Cone Using Second-Order Perturbation Approximations
An approximate analytical solution is obtained for hypersonic flow past a slender elliptic cone using second-order perturbation techniques in spherical coordinate systems. The analysis is based on perturbations of hypersonic flow past a circular cone aligned with the free stream, the perturbations stemming from the small cross-section eccentricity. By means of hypersonic approximations for the ...
متن کاملAcoustic attenuation performance of perforated dissipative mufflers with empty inlet/outlet extensions
The acoustic behavior of perforated dissipative circular mufflers with empty extended inlet/outlet is investigated in detail by means of a two-dimensional (2D) axisymmetric analytical approach that matches the acoustic pressure and velocity across the geometrical discontinuities, and the finite element method (FEM). The complex characteristic impedance, wavenumber, and perforation impedance are...
متن کاملReduction of the Compressor Inlet Infrasound Emission
The infrasounds attenuation is inefective mainly because of the lon~ sonic wave diffraction, so that the reduction of the infrasounds source is the only acceptable method. Unfortunately low frequency pressure pulsation has the great influence on the compressor operation. -Each change in suction line results in change of compressor volumetric efficiency. The paper presents examples of numerical ...
متن کاملA finite element approach for the acoustic modeling of perforated dissipative mufflers with non-homogeneous properties
In this work, a finite element approach is presented for modelling sound propagation in perforated dissipative mufflers with non-homogeneous properties. The spatial variations of the acoustic properties can arise, for example, from uneven filling processes during manufacture and degradation associated with the flow of soot particles within the absorbent material. First, the finite element metho...
متن کامل