Abstract
This investigation targets a tunnel that has an enlarged part in the cross section in which jet fans are installed. The purpose of this investigation is to confirm a simple theoretical formula of pressure gain that we proposed for this kind of tunnel. Wall friction inside the tunnel was examined using numerical simulation, and pressure gain was re-estimated by considering the effect of this friction. As a result, the estimated pressure gain agreed with numerical simulation, so that the present formula is considered useful to estimate the pressure gain in this kind of tunnels.
