Rapid calculation of the compression wave generated by a train entering a tunnel with a vented hood

A practical analytical scheme is proposed for making rapid numerical predictions of the compression wave generated when a high-speed train enters a tunnel fitted with a vented entrance hood. The method synthesises results from several analytical procedures developed during the past few years for treating different aspects of the tunnel-entry problem, including the effects of change in cross-sectional area at the hood-tunnel junction, high-speed jet flows from windows distributed along the length of the hood, frictional losses associated with separated turbulent flow between the tunnel and hood walls and the train, and the influence of train nose shape. Details are given in this paper for the simplest case of circular cylindrical tunnels and hoods of the type used in model scale testing and design studies. Typical predictions can be made in a few seconds on a personal computer (in contrast to the tens or hundreds of hours required for simulations using the Euler or Navier–Stokes equations on a high performance supercomputer). A summary is given of selected predictions and their comparisons with experiments performed at the Railway Technical Research Institute in Tokyo at train Mach numbers as large as 0.35 ( ∼ 425 km / h ) .