Influence of the nose shape of high-speed train on the piston effect at Walini tunnel.

A high-speed train is a form of transportation that connects between distant places, in this case, town to town of Jakarta and Bandung. Travel time using this means of transportation decreases since there will be no congestion as it uses dedicated railways along its travel route. During its journey, it will encounter many tunnels like the Walini tunnel. Many aerodynamic phenomena will occur and affect the train while entering, inside, and exiting the tunnel. These events will affect the whole-body surface of the train, the tunnel, and the nearby environment. The focus of the analysis of the effects is on the train's nose, influenced by the velocity and pressure that the train produces. Pressure and velocity inside the tunnel can be related to the piston effect. The pressure difference that the high-speed train brings from the outside environment into the tunnel at high speed is affected. Pressure is built up in front of the train, especially at the nose of the train. Due to its micro-pressure breakage that needs to travel to the rear part of the train to stabilize the aerodynamic condition before it becomes stable when 2-3 lengths of the train have exited the tunnel. In this paper, we will analyze the train nose shape's difference in affecting the piston effect inside the tunnel. The parameter used is when the entire train has entered the tunnel and is about to leave since the effect can be clearly seen at this particular time. [ABSTRACT FROM AUTHOR]