Aerodynamic interaction between static vehicles and wind barriers on railway bridges exposed to crosswinds

Huoyue, Xiang,Yongle, Li,Bin, Wang Techno-Press 2015 Wind and Structures, An International Journal (WAS Vol.20 No.2

Wind tunnel experiments are used to investigate the aerodynamic interactions between vehicles and wind barriers on a railway bridge. Wind barriers with four different heights (1.72 m, 2.05 m, 2.5 m and 2.95 m, full-scale) and three different porosities (0%, 30% and 40%) are studied to yield the aerodynamic coefficients of the vehicle and the wind barriers. The effects of the wind barriers on the aerodynamic coefficients of the vehicle are analyzed as well as the effects of the vehicle on the aerodynamic coefficients of the wind barriers. Finally, the relationship between the drag forces on the wind barriers and the aerodynamic coefficients of the vehicle are discussed. The results show that the wind barriers can significantly reduce the drag coefficients of the vehicle, but that porous wind barriers increase the lift forces on the vehicle. The windward vehicle will significantly reduce the drag coefficients of the porous wind barriers, but the windward and leeward vehicle will increase the drag coefficients of the solid wind barrier. The overturning moment coefficient is a linear function of the drag forces on the wind barriers if the full-scale height of the wind barriers $h{\leq}2.5m$ and the overturning moment coefficients $C_O{\geq}0$.

Aerodynamic interaction between static vehicles and wind barriers on railway bridges exposed to crosswinds

Xiang Huoyue,Li Yongle,Wang Bin 한국풍공학회 2015 Wind and Structures, An International Journal (WAS Vol.20 No.2

Wind tunnel experiments are used to investigate the aerodynamic interactions between vehiclesand wind barriers on a railway bridge. Wind barriers with four different heights (1.72 m, 2.05 m, 2.5 m and2.95 m, full-scale) and three different porosities (0%, 30% and 40%) are studied to yield the aerodynamiccoefficients of the vehicle and the wind barriers. The effects of the wind barriers on the aerodynamiccoefficients of the vehicle are analyzed as well as the effects of the vehicle on the aerodynamic coefficientsof the wind barriers. Finally, the relationship between the drag forces on the wind barriers and theaerodynamic coefficients of the vehicle are discussed. The results show that the wind barriers cansignificantly reduce the drag coefficients of the vehicle, but that porous wind barriers increase the lift forceson the vehicle. The windward vehicle will significantly reduce the drag coefficients of the porous windbarriers, but the windward and leeward vehicle will increase the drag coefficients of the solid wind barrier. The overturning moment coefficient is a linear function of the drag forces on the wind barriers if thefull-scale height of the wind barriers h≤2.5 m and the overturning moment coefficients CO≥0.

Numerical simulation on aerodynamic characteristics of moving van under the train-induced wind

Jiajun He,Huoyue Xiang,Wenyuan Ren,Yong-Le Li 한국풍공학회 2021 Wind and Structures, An International Journal (WAS Vol.33 No.1

Constructing combined highway–railway bridge brings concerns regarding the aerodynamic interference between train and road vehicle. Research on the interaction mechanism can help calculate the vehicle response for the assessment of travelling safety. In this work, computational fluid dynamics (CFD) verified by a moving model test was applied on researching the aerodynamic characteristics of a moving van under the influence of train-induced wind. Two processes - encounter process (train and van drive towards each other) and chase process (train surpasses the van), are compared. The aerodynamic forces and pressure distribution of the van as well as the flow fields around the vehicles during the interaction are analyzed coherently. The results reveal that the adjacent positive and negative pressure zones around the nose and tail of the train bring moving and centralized high-pressure zone on the van’s flank and generate significant aerodynamic variations, each variation contains at least two peak/valley values, and the middle carriage provide a stable transition between. Different superposition effect of the pressure zones results in difference between the encounter process and chase process, the variation trend of drag force and lift in the two processes are similar while the encounter has larger variation amplitude, in terms of pitching moment and yawing moment, more inversions of force happen in the encounter process but the variation amplitude is smaller. When the van runs near the nose of the train in the encounter, it gets the largest variation of drag force, lift force and rolling moment, while the largest variation of yawing moment and pitching moment happens when it runs near the nose of the train in the chase process.

Wind tunnel tests on flow fields of full-scale railway wind barriers

Su, Yang,Xiang, Huoyue,Fang, Chen,Wang, Lei,Li, Yongle Techno-Press 2017 Wind and Structures, An International Journal (WAS Vol.24 No.2

The present study provides a deeper understanding of the flow fields of a full-scale railway wind barriers by means of a wind tunnel test. First, the drag forces of the three wind barriers were measured using a force sensor, and the drag force coefficients were compared with a similar scale model. On this basis, the mean wind velocity and turbulence upwind and downwind of the wind barriers were measured. The effects of pore size and opening forms of the wind barrier were discussed. The results show that the test of the scaled wind barrier model may be unsafe, and it is suitable to adopt the full-scale wind barrier model. The pore size and the opening forms of wind barriers have a slight influence on the flow fields upwind of the wind barrier but have some influences on the flow fields and power spectra downwind of the wind barrier. The smaller pore size generates a lower turbulence density and value of the power spectrum near the wind barrier, and the porous wind barriers clearly provide better shelter than the bar-type wind barriers.

Dynamic analysis of wind-vehicle-bridge system considering additional moments of non-uniform winds by wind shielding effect of multi-limb tower

Xu Han,Huoyue Xiang,Xuli Chen,Yong-Le Li 한국풍공학회 2023 Wind and Structures, An International Journal (WAS Vol.36 No.1

To evaluate the wind shielding effect of bridge towers with multiple limbs on high-speed trains, a wind tunnel test was conducted to investigate the aerodynamic characteristics of vehicles traversing multi-limb towers, which represented a combination of the steady aerodynamic coefficient of the vehicle-bridge system and wind environment around the tower. Subsequently, the analysis model of wind-vehicle-bridge (WVB) system considering the additional moments caused by lift and drag forces under nonuniform wind was proposed, and the reliability and accuracy of the proposed model of WVB system were verified using another model. Finally, the factors influencing the wind shielding effect of multi-limb towers were analyzed. The results indicate that the wind speed distributions along the span exhibit two sudden changes, and the wind speed generally decreases with increasing wind direction angle. The pitching and yawing accelerations of vehicles under nonuniform wind loads significantly increase due to the additional pitching and yawing moments. The sudden change values of the lateral and yawing accelerations caused by the wind shielding effect of multi-limb tower are 0.43 m/s2 and 0.11 rad/s2 within 0.4 s, respectively. The results indicate that the wind shielding effect of a multi-limb tower is the controlling factor in WVB systems.

Wind tunnel tests on flow fields of full-scale railway wind barriers

Yang Su,Huoyue Xiang,Chen Fang,Lei Wang,Yongle Li 한국풍공학회 2017 Wind and Structures, An International Journal (WAS Vol.24 No.2

The present study provides a deeper understanding of the flow fields of a full-scale railway wind barriers by means of a wind tunnel test. First, the drag forces of the three wind barriers were measured using a force sensor, and the drag force coefficients were compared with a similar scale model. On this basis, the mean wind velocity and turbulence upwind and downwind of the wind barriers were measured. The effects of pore size and opening forms of the wind barrier were discussed. The results show that the test of the scaled wind barrier model may be unsafe, and it is suitable to adopt the full-scale wind barrier model. The pore size and the opening forms of wind barriers have a slight influence on the flow fields upwind of the wind barrier but have some influences on the flow fields and power spectra downwind of the wind barrier. The smaller pore size generates a lower turbulence density and value of the power spectrum near the wind barrier, and the porous wind barriers clearly provide better shelter than the bar-type wind barriers.

Optimization of longitudinal viscous dampers for a freight railway cable-stayed bridge under braking forces

Yu, Chuanjin,Xiang, Huoyue,Li, Yongle,Pan, Maosheng Techno-Press 2018 Smart Structures and Systems, An International Jou Vol.21 No.5

Under braking forces of a freight train, there are great longitudinal structural responses of a large freight railway cable-stayed bridge. To alleviate such adverse reactions, viscous dampers are required, whose parametric selection is one of important and arduous researches. Based on the longitudinal dynamics vehicle model, responses of a cable-stayed bridge are investigated under various cases. It shows that there is a notable effect of initial braking speeds and locations of a freight train on the structural responses. Under the most unfavorable braking condition, the parameter sensitivity analyses of viscous dampers are systematically performed. Meanwhile, a mixing method called BPNN-NSGA-II, combining the Back Propagation neural network (BPNN) and Non-Dominated Sorting Genetic Algorithm With Elitist Strategy (NSGA-II), is employed to optimize parameters of viscous dampers. The result shows that: 1. the relationships between the parameters of viscous dampers and the key longitudinal responses of the bridge are high nonlinear, which are completely different from each other; 2. the longitudinal displacement of the bridge main girder significantly decreases by the optimized viscous dampers.

Experimental Investigation on Aerodynamic Interference of Vehicles on Single-Level Rail-Cum-Road Bridge under Crosswinds

Jiajun He,Jin Zhu,Huoyue Xiang,Botao Zhang,Yongle Li,Bing Han 대한토목학회 2023 KSCE Journal of Civil Engineering Vol.27 No.8

Single-level rail-cum-road steel box girder is a relatively new form of bridge superstructure that accommodates railway and highway in the same level. The wind flow pattern over the bridge deck is quite complex and a new issue of aerodynamic interference between vehicles also rise up. This paper conducted an in-depth investigation on the aerodynamic characteristics of vehicles on a single-level rail-cum-road bridge as well as the aerodynamic interference among vehicles. The results reveal that the bridge deck makes the aerodynamic coefficients of vehicles on windward lanes vary a lot with respect to vehicle location and vehicle type, while it also well protects the train and leeward road vehicles from large wind load. Among all the vehicles, the van gets several of the largest aerodynamic coefficients and is considered as a critical vehicle. In terms of the vehicles’ interference, the upstream truck trailer brings significant aerodynamic variation for the overtaking vehicle, but its inadequate shelter effect yields fluctuation in the variation. An upstream truck trailer brings significant rise for the aerodynamic load of the train, larger distance between the train and the truck trailer will bring larger increase on the train’s aerodynamic load.