Analysis of aerodynamic performance and operation safety for trains passing through typical transition sections of Lanzhou-Xinjiang high-speed railway

Following the major adjustments to the train diagram of the nationwide railway network in China on July 1, 2023, 25T conventional passenger trains have been scheduled to operate across various sections of the Lanzhou-Xinjiang passenger dedicated line. This change necessitates urgent research into the wind-limit conditions for the operation of these trains to lower complications in operation scheduling and command while minimizing frequent suspensions of train services by improving the wind-limit conditions to the maximum extent under the premise of ensuring operational safety. In this study, based on a three-dimensional, unsteady, incompressible Realizable <italic>k</italic>-<italic>ε</italic> scale-resolving-hybrid (SRH) turbulence model, investigations were made into the aerodynamic load and flow field characteristics of 25T conventional passenger trains in a four-car formation passing through four typical sections K3017, K3018, K3030, and K3038. Zones with sudden changes in velocity distribution were identified in these transition sections, and causes for activating transient aerodynamic loads on the trains were analyzed. Overturning and derailment coefficients were determined for these trains through analyses based on a constructed vehicle system dynamics model. These coefficients were then used to establish the critical wind velocity curve for 25T conventional passenger trains passing through the typical transition sections equipped with wind protection facilities on Lanzhou-Xinjiang high-speed railway. Corresponding to running speeds of 40 km/h, 80 km/h, 120 km/h, and 160 km/h, the critical wind velocities were found to be 45.4 m/s, 41.6 m/s, 39.1 m/s, and 34.9 m/s, respectively. Compared with existing sections with windbreak walls on this railway, the speed limits for conventional passenger trains under strong wind conditions were greatly improved.