Showing papers in "Journal of Sound and Vibration in 1975"

TL;DR: In this paper, a theoretical expression for the far-field acoustic power spectral density produced by an airfoil in a subsonic turbulent stream is given in terms of quantities characteristics of the turbulence.

TL;DR: In this article, the relationship between the bounding frequencies of propagation zones of mono-coupled periodic systems and the natural frequencies of the individual elements of which the system is composed is studied.

TL;DR: In this paper, it was shown that the two main parameters governing the propagation of sound waves in gases contained in rigid cylindrical tubes, are the shear wave number, s = R ρ s ω / μ, and the reduced frequency, k = ωR/a 0, and that most of the most significant analytical solutions for the propagation constant, Γ, as given in the literature, can be expressed as simple expressions in terms of these two parameters.

TL;DR: In this paper, the nature of the characteristic wave motions is studied, and a characteristic receptance matrix for a characteristic wave is defined, and the equations governing the reflection process are set up, and used to formulate the equations for the natural frequencies and modes of a finite periodic system with arbitrary boundaries.

TL;DR: In this article, the sound field due to a point source above a plane boundary with a constant normal impedance was obtained by a double saddle point method of integration, which is similar to the one used in this paper.

TL;DR: In this article, a mathematical procedure is developed for calculating the parameters of a single-layer perforated-plate acoustic liner in order to achieve a specified acoustic resistance and reactance for single-frequency excitation.

TL;DR: In this paper, it was found that broad band jet noise can be amplified by a pure tone excitation as much as 6 to 7 dB, and an attenuator was constructed based on a simplified mathematical model which is able to reduce the jet noise amplification significantly.

TL;DR: In this article, the authors proposed a new solution for the external radiative pattern of acoustic modes in an unflanged circular duct in a form more suitable for practical computations, which predicts the same locations for the principal lobe and zeroes as would be obtained from the baffled model, with the added advantage of being able to predict sideline and aft radiation.

TL;DR: In this article, the authors presented a finite element model with nodal degrees of freedom which can satisfy all the forced and natural boundary conditions of a Timoshenko beam, and the mass and stiffness matrices of the element were derived from kinetic and strain energies by assigning polynomial expressions for total deflection and bending slope.

TL;DR: In this article, a mathematical model that enables one to predict the vortex-excited resonant response of bluff elastic cylinders is developed based on some previous work by the authors, a modified van der Pol equation is employed as the governing equation for the fluctuating lift on the cylinder and is coupled to the equation of motion of the cylinder.

TL;DR: The influence of temperature on the sound field of supersonic, shock-free jets has been studied experimentally by measuring the turbulent mixing noise in the far-field from four 2-inch diameter nozzles, operated in a carefully designed anechoic room that provides a free-field environment as discussed by the authors.

TL;DR: In this article, the authors used the dynamic analogue of the von Karman equations to study the symmetric response of a circular plate to a harmonic excitation when the frequency of the excitation is near one of the natural frequencies.

TL;DR: In this article, a mathematical model is introduced describing most of the basic phenomena observed in experiments, and a characteristic feature of the two-equations model is a non-linear aerodynamic damping term of fifth order.

TL;DR: In this article, the axisymmetric vibrations of radially polarized piezoelectric ceramic long tubes, whose cylindrical surfaces are electroded and subjected to an alternating voltage, were established for axisymetric vibrations.

TL;DR: In this paper, an expression for attenuation (insertion loss) of a muffler has been proposed in terms of convective terminal impedances and a velocity ratio, on the lines of the one existing for acoustic filters.

TL;DR: In this article, an elastic structure carrying a rigid circular cylindrical tank containing a liquid with a free surface is considered and an autoparametric coupling between a single structural freedom and the first antisymmetric sloshing mode is investigated theoretically and experimentally.

TL;DR: In this article, the residual spectral density and partial coherence are developed by using the known spectral response relationships for multivariate random processes, and avoiding specific reference to least-squares prediction.

TL;DR: In this paper, the authors derived an explicit expression for the amplitude with which each acoustic mode is generated by the Fourier transform of the solution, which amounts to solving the equation for a source distribution of fixed frequency and wavenumber.

TL;DR: In this paper, a set of tables for the first five symmetric and first five antisymmetric modes of a hollow or solid cylinder for circumferential wave numbers n = 0, 1, 2 is given.

TL;DR: In this paper, a mathematical model of large scale disturbances in a supersonic jet is presented in which the presence of large-scale disturbances not only enhances the unsteady entrainment of ambient gas into the jet flow but also causes the jet to vibrate laterally.

TL;DR: In this article, the Strouhal number expressed in terms of an effective diameter, defined as the frontal area per unit length of tube, is found to be nearly constant and to depend only on the ratio of fin spacing to tube diameter.

TL;DR: In this article, the response of the rolling tire is formulated in terms of the natural modes and frequencies of the non-contacting tire for contact loading due to rolling, braking, accelerating or cornering.

TL;DR: In this article, simple polynomial approximations and Galerkin's method are used to determine the response of a thin, elastic, rectangular plate clamped along the boundary and subjected to sinusoidal excitation.

TL;DR: In this article, the authors investigated the effect of the Mach number and temperature discontinuity mismatch between the tailpipe and the surrounding medium on aircraft engine noise and concluded that the temperature mismatch results in a sharp beaming of sound off to the side.

TL;DR: In this article, the energy flow in the case of plane wave transmission across a shear discontinuity is analyzed and this problem serves as a convenient test for conservation, and the energy principle developed by Blokhintsev is shown to be applicable.

TL;DR: In this paper, the mean and fluctuating pressure field on a two-dimensional circular cylinder have been measured in the Reynolds number range 0·8×105 −6×105 for uniform flow and for grid produced turbulence having longitudinal length scales ranging from 0·19D to 0·55D.

TL;DR: In this article, the authors deal with the determination of natural frequencies and modal shapes of an elastically restrained-free beam which carries a finite mass, M, at the free end.

TL;DR: In this paper, the lift and drag coefficients of one conductor in the wake of another were measured for three types of conductor under two conditions of free stream turbulence for various Reynolds numbers, and the undamped conditions were used to show that flutter is possible right across the wake, except on the centre line.

TL;DR: In this article, an analytic method of determining the resonant frequencies of generally orthotropic beams, where flexural to torsional coupling is caused by the character of the elastic material constants, is presented.

TL;DR: In this article, similarity laws governing the harmonic components of the sound radiated from centrifugal fans were investigated. Butler et al. showed that it is possible to extrapolate data from a model fan to other geometrically similar fans of different sizes.