Development of a forward design method for train airtightness: A case study of a metro express line

Abstract

Focusing on metro express lines, this study develops a train airtightness forward design method by deconstructing whole-vehicle pressure change and dynamic sealing index requirements into key airtight component static sealing indices. This is achieved through the utilization of theoretical calculations, simulation calculations, laboratory tests, and field tests. Firstly, a research framework for the train airtightness forward design method is established. Subsequently, a sealed train is manufactured based on existing capabilities, and the following research is conducted: 1) Establishment of a conversion formula between key airtight component static sealing indices and the theoretical whole-vehicle static sealing index. 2) Examination of the theoretical weight relationship between key airtight components and the whole-vehicle theoretical static sealing performance, revealing that the doors and the carriage body each contribute to almost 50 % of the entire train's static sealing performance. 3) Investigation into the relationship between whole-vehicle theoretical and actual static sealing indices, revealing that test values for head/tail car pressure retention duration and static sealing index are 16 % below theoretical values, while those for the middle car are 13 % lower than the theoretical values. 4) Assessment of the validity of current standards. 5) Establishment of a calculation method for the relationship between whole-vehicle dynamic and static sealing indices, discovering that the whole-vehicle dynamic sealing index is 0.034–0.081 times the whole-vehicle static sealing index. 6) Development of a Computational Fluid Dynamics (CFD) simulation method to calculate metro trains' external wall pressure, which is validated through real-vehicle test data. Finally, within this framework, the train airtightness forward design method is formulated by determining the unknown relationships among airtightness parameters, standard indices, and simulation methods. Importantly, the forward airtightness design process and method established in this study are not limited to metro trains alone. They also serve as valuable references for airtightness research and development in various other products with similar requirements, including locomotives, electric multiple units, high-speed trains, and maglev trains.