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1
Content available Mathematical Modelling of Sound Radiation from a T Junction of City Roads in Windy Conditions
Piddubniak O., Piddubniak N.
Archives of Acoustics
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2016
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Vol. 41, No. 3
543--558
EN
The sound radiation from vehicles travelling on the city roads with T junction was considered. The wind effect on acoustic field was taken into account. The solution of this problem was found with the help of the integral Fourier transforms and stationary phase method as the superposition of solutions for the cases of vehicles moving along the straight roads and roads with right-angle bend. As an example, the numerical analysis of traffic noise characteristics was carried out for the T junction city road on one of streets in the town of Łódź (Poland).
2
Content available Analysis of Spectral Characteristics of Sound Waves Scattered from a Cracked Cylindrical Elastic Shell Filled with a Viscous Fluid
Piddubniak O., Piddubniak N.
Archives of Acoustics
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2013
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Vol. 38, No. 3
335--350
EN
The scattering of plane steady-state sound waves from a viscous fluid-filled thin cylindrical shell weak- ened by a long linear slit and submerged in an ideal fluid is studied. For the description of vibrations of elastic objects the Kirchhoff-Love shell-theory approximation is used. An exact solution of this problem is obtained in the form of series with cylindrical harmonics. The numerical analysis is carried out for a steel shell filled with oil and immersed in seawater. The modules and phases of the scattering amplitudes versus the dimensionless wavenumber of the incident sound wave as well as directivity patterns of the scattered field are investigated taking into consideration the orientation of the slit on the elastic shell surface. The plots obtained show a considerable influence of the slit and viscous fluid filler on the diffraction process.
3
Content available Sound Radiation from a Roundabout
Piddubniak O., Piddubniak N.
Archives of Acoustics
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2010
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Vol. 35, No. 3
437-456
EN
Sound propagation from the vehicles moving on the city roundabout, with taking into account the wind is investigated. Solution of the problem for one moving sound source is found by means of the integral Fourier transforms extended over space variables and time. Inverse transforms are calculated approximately, using a stationary phase method and iterative technique. The solution for a general problem is obtained as a superposition of many partial solutions. The numerical analysis of noise characteristics is performed for the three-way Korfanty roundabout case in Łódz.
4
Content available remote Axially symmetric periodical wave processes in a rotating elastic hollow circular cylinder surrounded by an acoustic medium
Piddubniak O., Piddubniak N.
Archives of Acoustics
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2008
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Vol. 33, No. 3
303-322
EN
In this paper the spectral characteristics of a strain-stress state of an infinitely long elastic hollow circular cylinder with arbitrary thickness rotating about its axis of symmetry with time-dependent angular velocity is investigated. It is assumed that a cylinder is empty inside and surrounded by ideal (non-viscous) compressible fluid or gas. The exact solution of this problem is obtained using the Fourier transform with respect to time. Calculations are carried out for a case of the Armco iron tube immersed in water. The detailed analysis of temporal and spatial spectral characteristics of the elastic displacements and stresses, the material density and the power flow density averaged in the period of vibrations in elastic cylinder, are presented.
5
Determination of porosity of saturated solid using the effect of non-specular reflection of Gaussian sound beam
Piddubniak O., Pakowski Z.
Inżynieria Chemiczna i Procesowa
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2004
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T. 25, z. 3/3
1487-1493
EN
A new accoustical method of determination of porosity of the solid saturated by a liquid is proposed. The new method is based on the multiple application of the focused Gaussian beam of the quasi . harmonic sound waves locally irradiating a plane boundary interface between a fluid phase and porous medium in the mass transfer process, in particular, drying of the materials. The scanning of the sound beam on the boundary surface allows a possibility of the non-specular reflection. It is shown that maximum value of the wave power in the non-specular reflected sound can be achieved, when an angle of the incidence wave coincidences with a critical angle of the Rayleigh surface wave excitation in the porous elastic solid. A solution of the dispersion equation of this problem connected with the Rayleigh critical angle, from one hand, and porosity parameters of the reflecting body, from other hand. It allows immediately to determinate the initial porosity of the medium from the amplitude of non-specular reflected sound for each of the discrete acts of the sound irradiation. Numerical calculations demonstrate the effect of the non-specular reflection effect for a system: water . sandstone saturated by kerosene.
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