A study on the airtightness of a high-speed train using a reduced-scale method

Abstract

The pressure comfort of a high-speed train is closely related to the static and dynamic airtightness performance of the train carriage, and this performance is studied mainly with field surveys and tests on full-scale trains. Considering the high cost and difficulty of full-scale tests, the applicability of the reduced-scale model experiment method in the study of train carriage airtightness performance is worth exploring. In this study, a power–law relationship between the scale factors and static airtightness coefficients of carriage models was first established using numerical simulations, to determine the fundamental theoretical support for the reduced-scale model experiments. A series of static and moving model experiments were conducted on a newly designed 1/20th-scale special train carriage model. The static airtightness coefficients obtained from static model experiments showed a discrepancy less than 5% to their theoretical values, which revealed the experimental feasibility of the reduced-scale model for studying the static airtightness performance. The pressure spectrum characteristics of the measured pressure from the moving model experiment indicated that not only the high-intensity aerodynamic alternating pressure load with a frequency peak around St = 1.76 but also the high-frequency mechanical vibrations around St = 17.03 from the wheel-rail coupling system were experienced by the carriage body traveling through a tunnel, which might cause some potential leakages to appear on the carriage body. This provides a new understanding of the potential causes of the deterioration of the train’s dynamic airtightness performance.