Parameter optimization for improved aerodynamic performance of louver-type wind barrier for train-bridge system

2019 ◽  
Vol 26 (1) ◽  
pp. 229-240 ◽  
Author(s):  
Xu-hui He ◽  
Dong-xu Fang ◽  
Huan Li ◽  
Kang Shi
2016 ◽  
Vol 23 (3) ◽  
pp. 171-189 ◽  
Author(s):  
Xuhui He ◽  
Kang Shi ◽  
Teng Wu ◽  
Yunfeng Zou ◽  
Hanfeng Wang ◽  
...  

Author(s):  
Ye Liu ◽  
Yan Han ◽  
Peng Hu ◽  
C. S. Cai ◽  
Xuhui He

In this study, the influences of wind barriers on the aerodynamic characteristics of trains (e.g. a CRH2 train) on a highway-railway one-story bridge were investigated by using wind pressure measurement tests, and a reduction factor of overturning moment coefficients was analyzed for trains under wind barriers. Subsequently, based on a joint simulation employing SIMPACK and ANSYS, a wind–train–track–bridge system coupled vibration model was established, and the safety and comfort indexes of trains on the bridge were studied under different wind barrier parameters. The results show that the mean wind pressures and fluctuating wind pressures on the trains’ surface decrease generally if wind barriers are used. As a result, the dynamic responses of the trains also decrease in the whole process of crossing the bridge. Of particular note, the rate of the wheel load reductions and lateral wheel-axle forces can change from unsafe states to relative safe states due to the wind barriers. The influence of the porosity of the wind barriers on the mean wind pressures and fluctuating wind pressures on the windward sides and near the top corner surfaces of the trains are significantly greater than the influence from the height of the wind barriers. Within a certain range, decreasing the wind barrier porosities and increasing the wind barrier heights will significantly reduce the safety and comfort index values of trains on the bridge. It is found that when the porosity of the wind barrier is 40%, the optimal height of the wind barrier is determined as approximately 3.5[Formula: see text]m. At this height, the trains on the bridges are safer and run more smoothly and comfortably. Besides, through the dynamic response analysis of the wind–train–track–bridge system, it is found that the installation of wind barriers in cases with high wind speeds (30[Formula: see text]m/s) may have an adverse effect on the vertical vibration of the train–track–bridge system.


2020 ◽  
Vol 206 ◽  
pp. 104367
Author(s):  
Fanrong Xue ◽  
Yan Han ◽  
Yunfeng Zou ◽  
Xuhui He ◽  
Suren Chen

2017 ◽  
Vol 199 ◽  
pp. 3083-3090 ◽  
Author(s):  
Tian Zhang ◽  
Wei-wei Guo ◽  
Fei Du

Author(s):  
Xuhui He ◽  
Lei Zhou ◽  
Zhengwei Chen ◽  
Haiquan Jing ◽  
Yunfeng Zou ◽  
...  

This paper investigates the effect of a wind barrier on the aerodynamic performance of a train–bridge system under crosswind using a numerical simulation method. The studied bridge is a long-span cable-stayed bridge with a flat steel box girder, located in Chongqing, China. The flow field around the train–bridge system with and without a wind barrier is numerically simulated. Wind barrier porosities varying from 10 to 60% are evaluated. The tricomponent coefficients of the train, bridge, and train–bridge system are obtained and investigated in detail. The effect of the wind barrier on the aerodynamics of the train–bridge system is revealed through the determination of the aerodynamic forces, pressure mapping, and flow visualization. The results show that a wind barrier successfully decreases the mean velocity above the girder and consequently decreases the drag force and moment on the train; however, the wind barrier also significantly increases the drag force on the girder. Therefore, installation of a wind barrier improves the running safety of the train but is detrimental to the wind resistance of the bridge. Additionally, the efficiency of the wind barrier depends on the porosity. A lower porosity improves the train safety but is more detrimental to the bridge safety. An optimal wind barrier porosity of 30% is obtained based on the aerodynamic forces of both the train and the bridge. Compared to a train–bridge system without a wind barrier, the drag force and moment on the train decrease by 66.1 and 62.9%, respectively; the drag force on the bridge girder increases to 0.86, and the drag force on the train–bridge system equals that without the wind barrier.


2020 ◽  
Vol 14 (4) ◽  
pp. 7369-7378
Author(s):  
Ky-Quang Pham ◽  
Xuan-Truong Le ◽  
Cong-Truong Dinh

Splitter blades located between stator blades in a single-stage axial compressor were proposed and investigated in this work to find their effects on aerodynamic performance and operating stability. Aerodynamic performance of the compressor was evaluated using three-dimensional Reynolds-averaged Navier-Stokes equations using the k-e turbulence model with a scalable wall function. The numerical results for the typical performance parameters without stator splitter blades were validated in comparison with experimental data. The numerical results of a parametric study using four geometric parameters (chord length, coverage angle, height and position) of the stator splitter blades showed that the operational stability of the single-stage axial compressor enhances remarkably using the stator splitter blades. The splitters were effective in suppressing flow separation in the stator domain of the compressor at near-stall condition which affects considerably the aerodynamic performance of the compressor.


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