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To better understand the aerodynamic characteristics of a train-bridge system under crosswind, an in-house experimental apparatus was developed in a wind tunnel at Central South University (CSU). The new facility consists of trains, a bridge, U-shaped slide rails, and positioning systems with winches. A wireless data acquisition system for pressure measurements was mounted within the train carriage to avoid any potential aerodynamic interference. A 1:25 scaled model of CRH2 running over a simply supported girder bridge was tested in a wind tunnel. The aerodynamic characteristics of the train-bridge system under various combinations of crosswind speed, train speed, and vehicle location on the bridge were identified. The experimental results reveal that the cosine law for surface wind pressure on a train under crosswind is no longer valid when the train runs on the bridge. The moving model method can better capture the more practical aerodynamic characteristics and the impact of train movement on the bridge. The present study indicates that the wind tunnel experiments using the stationary model cannot fully reveal the aerodynamic characteristics of both the train and bridge during crossing. The results captured using this unique approach provide insight into the aerodynamic characteristics of trains and bridges. [ABSTRACT FROM AUTHOR]

Appropriate modeling of an experimental technology is necessary in order to estimate the aerodynamic characteristic of railway trains and infrastructure (e.g., bridges). Simulation of the earth's wind characteristics of nature is a well-established practice by using an atmospheric boundary wind tunnel. However, in the mountainous area, the wind characteristics are strikingly different from those of the plain area, the amplitude variation of wind is related to complex terrain. Compared with atmospheric boundary layer winds, which are customarily treated as stationary, winds associated with gust winds originating from mountain areas exhibit rapid changes during a short period. A lack of available field test data and testing techniques has hindered such knowledge of the effect of mountain wind on railway-related applications. To simulate the characteristics of gust winds and prepare for follow-up studies of the impact on the railway-related structures, a gust wind generator was developed in an atmospheric boundary wind tunnel — the CSU wind tunnel. Further, the performance of the gust-wind generator was studied and analyzed under the condition of the combined operation between a gust-wind generator and a wind tunnel. [ABSTRACT FROM AUTHOR]

With the increase of the running speed of the high-speed train (HST), aerodynamic interference between the HST and surrounding structures becomes more and more important. Traditional wind tunnel experiments using the stationary model can not fully reveal the pulsing behavior of the aerodynamic forces on both the HST and surrounding structures. This paper numerically investigates the aerodynamic characteristics of an HST running on a bridge in cross-wind. The simulation results reveal that when there is no wind barrier, the stationary model case with the yaw angle identical to the moving model case can roughly reproduce the main flow structures around the train. However, once the train runs downstream a wind barrier, the stationary model cannot reveal its aerodynamic characteristics regardless of the yaw angle adopted. The moving model scenario successfully captures the pulsing behavior of the forces on both the train and wind barrier, which is concealed in the cases with a stationary model. The present results indicate that only the moving model method can fully reveal the aerodynamic characteristics and interactions between the train and surrounding structures, especially in evaluating their dynamic response. [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]