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Abstract

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 Łódź.

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Authors and Affiliations

Olexa Piddubniak
Nadia Piddubniak
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Abstract

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.
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Authors and Affiliations

Olexa Piddubniak
Nadia Piddubniak
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Abstract

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 Łodź (Poland).

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Authors and Affiliations

Olexa Piddubniak
Nadia Piddubniak
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Abstract

The non-stationary problem of temperature distribution in a circular cylindrical channel of infinite length filled with a homogeneous biomass material moving with a constant velocity in the axial direction was investigated. The heat source was a shaftless helical screw (or auger), which was heated with an electric current due to the Joule–Lenz effect and rotated uniformly around the axis of symmetry of the channel. Similar problems arise in the thermal processing of biomaterials using screw conveyor in pyrolysis and mass sterilization and pasteurization of food products. The problem is solved using the expansion of given and required functions in Fourier series over angular coordinate and integral Fourier and Laplace transforms over axial coordinate and time, respectively. As a result, the temperature field is obtained as the sum of two components, one of which, global, is proportional to time, and the other, which forms the microstructure of the temperature profile, is given by Fourier–Bessel series. The coefficients of the series are determined by the integrals calculated using the Romberg method. Based on the numerical calculations, the analysis of the space-time microstructure of the temperature field in the canal was performed. A significant dependence of the features of this microstructure on the geometric, kinematic and thermodynamic characteristics of the filling biomass and the screw was revealed.
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Authors and Affiliations

Stanisław Ledakowicz
1
ORCID: ORCID
Olexa Piddubniak
1

  1. Faculty of Process and Environmental Engineering, Lodz University of Technology, Wolczanska St. 215, 90-924 Lodz, Poland

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