THE AERODYNAMICS OF VEHICLES PASSING THROUGH TUNNELS

The problem of a vehicle entering and passing through a tunnel is considered. It is shown that the incompressible approximation provides the basic solution and the modifications from this basic solution caused by the compressible wave effects. The effect on the aerodynamics of different propulsion systems is described. The effects of vehicle length, tunnel entrance configurations, and air shafts on vehicle drag and tunnel flow field are considered. The conditions under which the waves generated by the vehicle might escape from the tunnel to cause an exit boom are determined.