An experimental and analytical investigation has been made on the pressure waves generated when a high-speed train passes through a short tunnel portals on both sides of which are fitted with extended hoods. These pressure waves, which are essentially of a nature of infrasound, consist of multiple reflections of a compression or expansion wave inside the tunnel, 'entry-wave' and 'exit-wave' from the tunnel portals, and the near field pressure fluctuations produced by the nose and tail parts of the passing train. By the analytical method adopted in this paper, the results from several analytical procedures developed during the past years for treating the tunnel-entry problem and the near field pressure fluctuations around the passing train have been synthesized. The infrasound waveforms obtained by analysis have been found to be in good accord with those obtained by the model-scale experimentation conducted for a short tunnel with hoods on both portals. The analytical method presented here will permit the designer to investigate an effectiveness of a portal-hood at the entrance or the exit, a range of suitable hood length and diameter, and a selection of appropriate train nose profiles.
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