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• The slipstream of the CR400 high-speed train is experimentally investigated by a moving train rig. • Measured by a point cloud of 25-locations, the ensemble-averaged profiles, spatial variations, gusts, and time–frequency characteristics of the slipstream were analyzed. • The spatial–temporal variation in the properties of flow around the head car has been explained regarding the shape of the train. This paper experimentally investigates the characteristics of the velocity field induced by the slipstream from the leading carriage model of a CR 400 high-speed train. The tests were carried out using a 1:16.8 scale model on a moving model rig developed at the Central South University, PRC. The slipstream velocity field was measured at a point cloud involving 25 locations on a plane orthogonal to the track orientation. Aiming at understanding the slipstream ensemble characteristics, especially those unique to the CR400 train, observations were analyzed to evaluate the ensemble-averaged profiles, spatial variations, gusts and time–frequency characteristics of velocity fluctuations in the slipstream. The results suggest that the moving train model and testing rig used in this study capture the unsteady and time-variant features of the slipstream. The spatiotemporal profile of the slipstream usually includes a primary and a secondary peak at the nose tip and the region immediately next to it, respectively. Among the collection of locations studied, the primary peak reaches its maximum at a lateral location close to the train side at the nose height. Finally, the time–frequency portraits of the spatiotemporal variations of the slipstream were obtained using wavelet scalograms of the velocity field, which offered an insightful understanding of the various scales of velocity fluctuations around the nose and their locale. [ABSTRACT FROM AUTHOR]

[Display omitted] • Identified current situation and challenges of high-speed railway aerodynamics. • Aerodynamics of train, bridge, train-bridge system and their factors are discussed. • In-depth review of wind tunnel testing for train, bridge, and train-bridge system. • Discussed limitations of existing experiments and tendencies in applications. • Proposed and developed some platforms for aerodynamic issues of train-bridge system. Wind tunnel tests have been widely applied in aerodynamic investigations owing to their unique advantages. However, it is difficult to theoretically establish a simplified symmetry or two-dimensional model because of the relative motion of the structures and proximity of the train to the ground/infrastructure. Additionally, railway-related aerodynamic problems tend to be more challenging than those encountered in other engineering structures. Moreover, transient and crosswind effects, as well as complex operation environments, need to be considered, thereby making aerodynamic analyses of train–bridge systems challenging. Advanced manufacturing methodologies can reproduce realistic scenarios of high-speed train (HST) operations in a wind tunnel. The development of a controllable and affordable experimental method presents considerable research opportunities and challenges. There exists a strong correlation between wind tunnel experimental methods and the understanding of aerodynamic mechanisms, and some wind tunnel tests are dedicated to identifying the aerodynamic behavior using specific test systems. This study mainly describes the types of tests typically performed in a wind tunnel to analyze the aerodynamic issues of train–bridge systems under wind action. To identify and understand the individual role of the above mentioned-correlated systems, trains and bridges in wind tunnel tests are described separately. High-speed trains on bridges must be made safe and environmentally friendly, and a few cases are presented as indications to reconsider our aerodynamic research priorities. Thus, advanced experimental activities have been proposed in the Central South University (CSU) wind tunnel, representing helpful practices in defining the real-world aerodynamic behavior of wind-vehicle-bridge systems. [ABSTRACT FROM AUTHOR]