Influence of train underbody gap on the formation of entry compression wave in a high-speed railway tunnel

초록

Stationary air inside a railway tunnel undergoes piston effect due to ingress of highspeed trains to form a distinct compression wave near the entrance of tunnel. Due to this effect, the two most important parameters that are very well known to affect the intensity of entry compression wave are blockage ratio (c/s. area ratio of train to tunnel) and the train speed. But, factors that affect the development process or the formation process of a compression wave are still unknown. The length of the fully developed compression wave is also an unknown phenomenon which needs to be investigated. In the current study, the formation process of entry compression wave and the effect of train under body gap on the development of entry compression are studied using CFD technique. With the means of three different train underbody gap cases it is demonstrated that the lower underbody gap case has higher formation length as compared to higher underbody gap cases.