Journal Article10.2514/3.60553
Finite Difference Method for Computing Sound Propagation in Nonuniform Ducts
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TL;DR: In this article, a stochastic analysis of a single degree of freedom system subjected to random wind and seismic excitations to study the response characteristics was undertaken by the authors, where the exciting force was assumed to be nonstationary in character, and was represented by the product of a deterministic shape function and a stationary random process characterized by its power spectral density.
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Abstract: Conclusion Compared to the rigorous procedures the solution to the previously stated problem, given by Eqs (4) and (5) is approximate, but avoids the cumbersome calculations involved in the former In this connection, the stochastic analysis of a single degree of freedom system subjected to random wind and seismic excitations to study the response characteristics was undertaken by the authors The exciting force was assumed to be nonstationary in character, and was represented by the product of a deterministic shape function and a stationary random process characterized by its power spectral density The choice of deterministic function and power spectral density was based on certain characteristics observed in a large number of past records of excitation process The application of Eqs (4) and (5) to study the peak response characteristics of the system revealed that the probability estimates for various appropriate values of X are about 05% below those obtained by an exact procedure
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Citations
A finite element method for transmission in non-uniform ducts without flow Comparison with the method of weighted residuals
R.J. Astley,Walter Eversman +1 more
TL;DR: In this article, a finite element method was developed for the study of transmission of sound in non-uniform ducts without flow, and the formulation is based on a weighted residual approach and eight noded isoparametric elements are used.
69
Transmission of sound through nonuniform circular ducts with compressible mean flows
A. H. Nayfeh,B. S. Shaker,J. E. Kaiser +2 more
- 01 May 1980
TL;DR: In this paper, an acoustic theory is developed to determine the sound transmission and attenuation through an infinite, hard-walled or lined, circular duct carrying compressible, sheared, mean flows and having a variable cross section.
Determination of Turbofan Inlet Acoustics Using Finite Elements
TL;DR: In this paper, the authors applied the finite element method in combination with Galerkin's method in the determination of the acoustic properties of turbofan inlets containing high subsonic Mach number steady flows.
39
Time-dependent difference theory for noise propagation in a two-dimensional duct
TL;DR: In this paper, a time dependent numerical formulation was derived for sound propagation in a two dimensional straight soft-walled duct in the absence of mean flow, and the time dependent governing acousticdifference equations and boundary conditions were developed along with the maximum stable time increment.
An iterative finite element-integral technique for predicting sound radiation from turbofan inlets in steady flight
TL;DR: In this paper, a new iterative solution technique for predicting the sound field radiated from a turbofan inlet in steady flight is presented, where sound field is divided into two regions.
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References
Attenuation of sound in soft-walled circular ducts
E. J. Rice
- 01 Jan 1968
TL;DR: Linearized wave equation with associated boundary conditions for predicting sound attenuation in soft walled circular ducts was used in this article, where the boundary conditions were defined by a linear wave equation.
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