Influence of operational speed and tunnel length on piston wind characteristics in Jakarta-Bandung high-speed railway project

Indonesia is developing its first high-speed railway that will be connecting Jakarta and Bandung. Given the nature of the landscape, the railway will have several tunnels along the route, including two tunnels in Halim and Walini. When a high-speed train passes along a tunnel, there is a phenomenon called the piston effect. The piston effect may lead to some concerns, such as aural discomfort among passengers and tunnel boom. One of the piston effect's components is piston wind, the wind gusts around the train when it travels along the tunnel. This study aimed to understand the piston effect phenomenon, the behavior of piston wind and its influencing factors. The study was conducted by simulating the movement of a 1:50 simplified high-speed train model along the tunnel in computational fluid dynamics software. The study found that when the train moves in the tunnel, there are wind gusts at both the front and back of the train. The wind velocity at the area closer to the train is bigger than other areas of the tunnel. The study also showed that operational speed has a more significant influence on the wind velocity behavior in high-speed train tunnels than tunnel length.