The severe shaking due to wind speed variation in high-speed trains has a negative impact on driving safety and riding comfort. It is difficult to solve this problem by directly applying civil engineering technology because of the actual conditions. Therefore, set up a reasonable train operation plan considering the wind speed variation under strong winds is very important. In this study, a multi-body simulation model of a CRH2 high-speed rail vehicle is constructed, and the overturning coefficient is set as the safety limit, we established a crosswind model on the basis of measured wind speed curves and investigated the effect of the rate of wind speed changes, the duration of maximum wind speed and the variation of wind speed in different amplitude on the dynamics of the high-speed train. Considering the most critical wind speed variation conditions, the characteristic wind curve is obtained, which can be used as a reference to set up a reasonable train operation scheme considering the wind speed variation.

Assessment of the vibration of high-speed trains negotiating complex sections of terrain under strong wind conditions is very important for research into the operation safety and comfort of passengers on high-speed trains. To assess the vibration of high-speed trains negotiating complex sections of terrain under strong wind conditions, we performed a field measurement when the train passes through typical sections of complex terrain along the Lanzhou–Xinjiang high-speed railway in China. We selected the lateral vibration conditions, including the roll angle and lateral displacement of car-body gravity centre through two typical representative sections (embankment–tunnel–embankment and embankment–rectangular transition–cutting) for analysis. The results show that the severe car-swaying phenomenon occurs when the high-speed train moves through the test section, and the car-body lateral vibration characteristic is related significantly to the state of the terrain and topography along the railway. The main causes for this car-swaying phenomenon may be the transitions between different windproof structures, and the greater the scale of the transition region between different windproof structures or landform changes, the more obvious the car-swaying phenomenon becomes. The lateral vibration of the car-body is relatively steady when the train is running through terrain with minor changes in topography, such as the windbreak installed on the bridge and embankment, but the tail car sways more violently than the head car. When the vehicle runs from the windbreak installed on the embankment into the tunnel (or in the opposite direction), the tail car sways more intensely than the head car, and the head car runs relatively stable in the tunnel.

Monitoring vehicle operation conditions has become significantly important in modern high-speed railway systems. However, the operational impact of monitoring the roll angle of vehicle bodies has principally been limited to tilting trains, while few studies have focused on monitoring the running posture of vehicle bodies during operation. We propose a real-time posture monitoring method to fulfil real-time monitoring requirements, by taking rail surfaces and centrelines as detection references. In realising the proposed method, we built a mathematical computational model based on space coordinate transformations to calculate attitude angles of vehicles in operation and vertical and lateral vibration displacements of single measuring points. Moreover, comparison and verification of reliability between system and field results were conducted. Results show that monitoring of the roll angles of car bodies obtained through the system exhibit variation trends similar to those converted from the dynamic deflection of bogie secondary air springs. The monitoring results of two identical conditions were basically the same, highlighting repeatability and good monitoring accuracy. Therefore, our monitoring results were reliable in reflecting posture changes in running railway vehicles.

Investigating the transient behaviour of liquid CO₂ decompression is of great importance to ensure the safety of pipeline transportation in carbon capture and storage (CCS) technology. A computational fluid dynamics (CFD) decompression model based on the non-equilibrium phase transition and Span–Wagner equation of state (EoS) was developed to study the effects of actual flowing state within the pipeline on the transient behaviour of liquid CO₂ decompression. Then, the CFD model was verified by comparing the simulated results to test data of a large-scale “shock tube” with an inner diameter of 146.36 mm. The results showed that the evaporation coefficient had a significant impact on the transition behaviour of CO₂ decompression, while the condensation coefficient made no difference. When the evaporation coefficient was 15 s⁻¹, the CFD-predicted results were in good agreement with the test results. Moreover, the effects of flow velocity on transient behaviour of liquid CO₂ decompression were further investigated. It was found that the flow velocity affected the temperature drop of liquid CO₂ during decompression, thereby affecting the phase transition of liquid CO₂. In addition, the initial flow velocity also showed a significant influence on the transient behaviour of CO₂ outside the pipe.

New engineering phenomena in China have renewed interest in research on the dynamic risk boundaries and characteristics of train overturning, derailment, and the interaction mechanism with aerodynamic loads in windy conditions. This study focuses on this challenge, the train aerodynamic loads characteristics, dynamic response and safety risk characteristics, and the contribution rate of different aerodynamic loads to train safety risks in different wind scenarios were investigated by computational fluid dynamics and multi-body dynamics simulation. The results reveal that when a train is completely exposed to strong winds with or without a windbreak, the safety risk assessment should focus on the overturning coefficient of the first wheelset of the first bogie of the head car. When the train is gradually exposed to strong winds, the probability of the train derailing risk is greatly increased. The train safety risk assessment should not only focus on the overturning coefficient, and more attention should be paid to the derailment coefficient of the first wheelset of the first bogie of the head car. In addition, there may be a risk of misjudgment in assessing the crosswind safety of trains from the aerodynamic point of view only by lateral force, lift force, and roll moment.

An in-depth understanding of car-body vibration characteristics is the key to developing more reasonable operational safety and discomfort evaluation indicators. However, few scholars or research institutions have focused on this topic, and the car-body vibration characteristics that are caused by different complex aerodynamic factors are not clear. Therefore, in this study, different train car-body vibrations under different conditions were investigated using full-scale tests from 2014 to 2016. The results revealed that the car-body vibration for different aerodynamic conditions was mainly low-frequency rolling and traversing motion below 1 Hz, and the primary frequency was close to the car-body lower-centre rolling natural frequency. In addition, the evaluations of the train operational safety and the vibrational comfort could be considered coupled under strong wind conditions. There was a strong line relationship between the car-body roll angle and the train overturning coefficient under strong wind conditions, hence, predicting the train’s overturning risk by the car-body roll angle was feasible.