Compression Wave Generated by a High-Speed Train Entering a Tunnel Fitted with a Hood with a Long Slit Window

Abstract

An investigation is made of the use of long, slit-like windows in the wall of a rectangular, tunnel-entrance hood to suppress the harmful environmental impact of the compression wave produced as a high-speed train enters a long tunnel. Model scale testing and numerical simulation indicate that when the cross-sectional area of the hood is larger than that of the tunnel, optima reduction in the maximum compression wave pressure gradient is achieved when the width of the slit window decreases inwards from the hood entrance, and when total length of the slit is no more than about 80% of the hood length. For a ‘low hood’ whose cross-sectional area is close to that of the tunnel, a more nearly optimal behaviour is furnished by a long uniform slit that extends over the whole length of the hood.