Eine Plattform für die Wissenschaft: Bauingenieurwesen, Architektur und Urbanistik
Eine Plattform für die Wissenschaft: Bauingenieurwesen, Architektur und Urbanistik
On the infrasound generated when a train enters a tunnel
An analysis is made of the 'open air infrasound' generated when a train enters a tunnel. For a tunnel of nominal radius R and train speed U the acoustic frequency ~U/R and wavelength ~R/M much greater than R, where M is the train Mach number. Infrasound is inaudible, but the pressure fluctuations generated by a high-speed train (M greater than 0.2) can cause annoying vibrations and 'rattles' in dwellings and other buildings close to a tunnel portal. Detailed calculations are presented in this paper for a 'hood-like' portal modelled analytically by the end of a circular cylindrical, thin-walled duct, and for an axisymmetric 'train' entering along the axis of the duct. A slender body approximation is used to model the influence of the moving train, and the acoustic problem is solved using the exact Green's function for a semi-infinite cylinder. Predictions are in good agreement with recent track-side measurements reported by Iida et al. (Proceedings of the 50th Japan National Congress on Theoretical and Applied Mechanics) for model scale experiments conducted at Mach numbers M as large as 0.33. However, both measurements and theory indicate that in applications at full scale it may be important to include in estimates of the infrasound the non-acoustic 'near-field' pressures produced by the passing train.
On the infrasound generated when a train enters a tunnel
An analysis is made of the 'open air infrasound' generated when a train enters a tunnel. For a tunnel of nominal radius R and train speed U the acoustic frequency ~U/R and wavelength ~R/M much greater than R, where M is the train Mach number. Infrasound is inaudible, but the pressure fluctuations generated by a high-speed train (M greater than 0.2) can cause annoying vibrations and 'rattles' in dwellings and other buildings close to a tunnel portal. Detailed calculations are presented in this paper for a 'hood-like' portal modelled analytically by the end of a circular cylindrical, thin-walled duct, and for an axisymmetric 'train' entering along the axis of the duct. A slender body approximation is used to model the influence of the moving train, and the acoustic problem is solved using the exact Green's function for a semi-infinite cylinder. Predictions are in good agreement with recent track-side measurements reported by Iida et al. (Proceedings of the 50th Japan National Congress on Theoretical and Applied Mechanics) for model scale experiments conducted at Mach numbers M as large as 0.33. However, both measurements and theory indicate that in applications at full scale it may be important to include in estimates of the infrasound the non-acoustic 'near-field' pressures produced by the passing train.
On the infrasound generated when a train enters a tunnel
Über die Erzeugung von Infraschall bei der Einfahrt eines Zuges in einen Tunnel
Howe, M.S. (Autor:in)
Journal of Fluids and Structures ; 17 ; 629-642
2003
14 Seiten, 8 Bilder, 20 Quellen
Aufsatz (Zeitschrift)
Englisch
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