Wind loads on a moving vehicle–bridge deck system by wind-tunnel model test

Yongle Li,Peng Hu,You-Lin Xu,Mingjin Zhang,Haili Liao 한국풍공학회 2014 Wind and Structures, An International Journal (WAS Vol.19 No.2

Wind-vehicle-bridge (WVB) interaction can be regarded as a coupled vibration system. Aerodynamic forces and moment on vehicles and bridge decks play an important role in the vibration analysis of the coupled WVB system. High-speed vehicle motion has certain effects on the aerodynamic characteristics of a vehicle-bridge system under crosswinds, but it is not taken into account in most previous studies. In this study, a new testing system with a moving vehicle model was developed to directly measure the aerodynamic forces and moment on the vehicle and bridge deck when the vehicle model moved on the bridge deck under crosswinds in a large wind tunnel. The testing system, with a total length of 18.0 m, consisted of three main parts: vehicle-bridge model system, motion system and signal measuring system. The wind speed, vehicle speed, test objects and relative position of the vehicle to the bridge deck could be easily altered for different test cases. The aerodynamic forces and moment on the moving vehicle and bridge deck were measured utilizing the new testing system. The effects of the vehicle speed, wind yaw angle, rail track position and vehicle type on the aerodynamic characteristics of the vehicle and bridge deck were investigated. In addition, a data processing method was proposed according to the characteristics of the dynamic testing signals to determine the variations of aerodynamic forces and moment on the moving vehicle and bridge deck. Three-car and single-car models were employed as the moving rail vehicle model and road vehicle model, respectively. The results indicate that the drag and lift coefficients of the vehicle tend to increase with the increase of the vehicle speed and the decrease of the resultant wind yaw angle and that the vehicle speed has more significant effect on the aerodynamic coefficients of the single-car model than on those of the three-car model. This study also reveals that the aerodynamic coefficients of the vehicle and bridge deck are strongly influenced by the rail track positions, while the aerodynamic coefficients of the bridge deck are insensitive to the vehicle speed or resultant wind yaw angle.

Wind-tunnel study of wake galloping of parallel cables on cable-stayed bridges and its suppression

Li, Yongle,Wu, Mengxue,Chen, Xinzhong,Wang, Tao,Liao, Haili Techno-Press 2013 Wind and Structures, An International Journal (WAS Vol.16 No.3

Flexible stay cables on cable-stayed bridges are three-dimensional. They sag and flex in the complex wind environment, which is a different situation to ideal rigid cylinders in two-dimensional wind flow. Aerodynamic interference and the response characteristics of wake galloping of full-scale parallel cables are potentially different due to three-dimensional flows around cables. This study presents a comprehensive wind tunnel investigation of wake galloping of parallel stay cables using three-dimensional aeroelastic cable models. The wind tunnel study focuses on the large spacing instability range, addressing the effects of cable separation, wind yaw angle, and wind angle of attack on wake galloping response. To investigate the effectiveness of vibration suppression measures, wind tunnel studies on the transversely connected cable systems for two types of connections (flexibility and rigidity) at two positions (mid-span and quarter-span) were also conducted. This experimental study provides useful insights for better understanding the characteristics of wake galloping that will help in establishing a guideline for the wind-resistant design of the cable system on cable-stayed bridges.

Wind-tunnel study of wake galloping of parallel cables on cable-stayed bridges and its suppression

Yongle Li,Mengxue Wu,Xinzhong Chen,Tao Wang,Haili Liao 한국풍공학회 2013 Wind and Structures, An International Journal (WAS Vol.16 No.3

Flexible stay cables on cable-stayed bridges are three-dimensional. They sag and flex in the complex wind environment, which is a different situation to ideal rigid cylinders in two-dimensional wind flow. Aerodynamic interference and the response characteristics of wake galloping of full-scale parallel cables are potentially different due to three-dimensional flows around cables. This study presents a comprehensive wind tunnel investigation of wake galloping of parallel stay cables using three-dimensional aeroelastic cable models. The wind tunnel study focuses on the large spacing instability range, addressing the effects of cable separation, wind yaw angle, and wind angle of attack on wake galloping response. To investigate the effectiveness of vibration suppression measures, wind tunnel studies on the transversely connected cable systems for two types of connections (flexibility and rigidity) at two positions (mid-span and quarter-span) were also conducted. This experimental study provides useful insights for better understanding the characteristics of wake galloping that will help in establishing a guideline for the wind-resistant design of the cable system on cable-stayed bridges.

Aerostatic and buffeting response characteristics of catwalk in a long-span suspension bridge

Yongle Li,Dongxu Wang,Chupeng Wu,Xinzhong Chen 한국풍공학회 2014 Wind and Structures, An International Journal (WAS Vol.19 No.6

This study presents a comprehensive investigation of the aerostatic and buffeting response characteristics of a suspension bridge catwalk. The three-dimensional aerostatic response analysis was carried out taking into account the geometric nonlinearity and nonlinear dependence of wind loads on the angle of attack. The buffeting response analysis was performed in the time domain. The aerostatic and buffeting responses of the catwalk show strong coupling of vertical and lateral vibrations. The lateral displacement is the main component of the wind-induced static and buffeting response of the catwalk

Wind loads on a moving vehicle-bridge deck system by wind-tunnel model test

Li, Yongle,Hu, Peng,Xu, You-Lin,Zhang, Mingjin,Liao, Haili Techno-Press 2014 Wind and Structures, An International Journal (WAS Vol.19 No.2

Wind-vehicle-bridge (WVB) interaction can be regarded as a coupled vibration system. Aerodynamic forces and moment on vehicles and bridge decks play an important role in the vibration analysis of the coupled WVB system. High-speed vehicle motion has certain effects on the aerodynamic characteristics of a vehicle-bridge system under crosswinds, but it is not taken into account in most previous studies. In this study, a new testing system with a moving vehicle model was developed to directly measure the aerodynamic forces and moment on the vehicle and bridge deck when the vehicle model moved on the bridge deck under crosswinds in a large wind tunnel. The testing system, with a total length of 18.0 m, consisted of three main parts: vehicle-bridge model system, motion system and signal measuring system. The wind speed, vehicle speed, test objects and relative position of the vehicle to the bridge deck could be easily altered for different test cases. The aerodynamic forces and moment on the moving vehicle and bridge deck were measured utilizing the new testing system. The effects of the vehicle speed, wind yaw angle, rail track position and vehicle type on the aerodynamic characteristics of the vehicle and bridge deck were investigated. In addition, a data processing method was proposed according to the characteristics of the dynamic testing signals to determine the variations of aerodynamic forces and moment on the moving vehicle and bridge deck. Three-car and single-car models were employed as the moving rail vehicle model and road vehicle model, respectively. The results indicate that the drag and lift coefficients of the vehicle tend to increase with the increase of the vehicle speed and the decrease of the resultant wind yaw angle and that the vehicle speed has more significant effect on the aerodynamic coefficients of the single-car model than on those of the three-car model. This study also reveals that the aerodynamic coefficients of the vehicle and bridge deck are strongly influenced by the rail track positions, while the aerodynamic coefficients of the bridge deck are insensitive to the vehicle speed or resultant wind yaw angle.

Aerostatic and buffeting response characteristics of catwalk in a long-span suspension bridge

Li, Yongle,Wang, Dongxu,Wu, Chupeng,Chen, Xinzhong Techno-Press 2014 Wind and Structures, An International Journal (WAS Vol.19 No.6

This study presents a comprehensive investigation of the aerostatic and buffeting response characteristics of a suspension bridge catwalk. The three-dimensional aerostatic response analysis was carried out taking into account the geometric nonlinearity and nonlinear dependence of wind loads on the angle of attack. The buffeting response analysis was performed in the time domain. The aerostatic and buffeting responses of the catwalk show strong coupling of vertical and lateral vibrations. The lateral displacement is the main component of the wind-induced static and buffeting response of the catwalk.

FABRICATION OF SQUARAINE DYE SENSITIZED SPHERICAL ZINC OXIDE NANOCOMPOSITES AND THEIR VISIBLE-LIGHT INDUCED PHOTOCATALYTIC ACTIVITY

YONGLING FANG,SONG XU,ZHONGYU LI,DANAN HAN,DAYONG LU 성균관대학교(자연과학캠퍼스) 성균나노과학기술원 2014 NANO Vol.9 No.3

A 1,3-bis[(3,3-dimethylindolin-2-ylidene)methyl]squaraine (ISQ) dye sensitized ZnO nanocompo-sites via two di®erent preparation methods including hydrothermal and ultrasonic sensitizationprocesses are discussed in this paper. The as-prepared composites were characterized by the X-raydi®raction (XRD), UV-Vis di®use re°ectance spectroscopy (DRS), Raman spectroscopy, andtransmission electron microscopy (TEM). Based on the XRD patterns and TEM images, the ISQ/ZnO nanocomposites still kept the characteristic peaks and the basic morphology of ZnO and ISQdye. The photocatalytic activity of ISQ/ZnO nanocomposites was investigated by degradingmethylene blue (MB) under visible-light illumination. Compared with the MB self-degradation rate,the photocatalytic activity of the ISQ/ZnO composites was enhanced remarkably. The ISQ/ZnOnanocomposites fabricated by ultrasonic sensitization method exhibited excellent photocatalyticdegradation rate, approximately 20% higher than that of the hydrothermal sensitization one.

Analysis and study of compact inductive power transfer systems for EV charging

Ai, Yongle,Hu, Xiaoqi,Li, Xing,Zhang, Xin The Korean Institute of Power Electronics 2021 JOURNAL OF POWER ELECTRONICS Vol.21 No.5

The double-sided LCC topology provides an efficient compensation method for electric vehicle (EV) wireless charging systems. However, the existence of two compensation coils results in an electric vehicle wireless charging device with a large volume, high power consumption, and low efficiency. To solve these problems, this paper proposes a wireless charging structure in which the compensation coils are separately integrated into the transmitting and receiving coils. First, the number of turns of the transmitting coil is optimized to maximize the coupling coefficient of the transmitting coil. Secondly, to minimize the redundant coupling effect, the relative placement of the compensation coils is studied. Based on the proposed coil integration method, it is possible to ignore the redundant coupling between the compensation coils and the transmitting and receiving coils. Then, the Ansys Maxwell and Ansys Twin Builder are used to build a joint simulation circuit to construct the proposed wireless charging system. Simulation and experimental results show that the system output power is 3.09 kW with a gap of 150 mm, and that the transmission efficiency is 95.49%. In addition, the integrated solution has a high transmission efficiency in the presence of front-to-back misalignment and vertical misalignment of electric vehicles.

The appropriate shape of the boundary transition section for a mountain-gorge terrain model in a wind tunnel test

Hu, Peng,Li, Yongle,Huang, Guoqing,Kang, Rui,Liao, Haili Techno-Press 2015 Wind and Structures, An International Journal (WAS Vol.20 No.1

Characterization of wind flows over a complex terrain, especially mountain-gorge terrain (referred to as the very complex terrain with rolling mountains and deep narrow gorges), is an important issue for design and operation of long-span bridges constructed in this area. In both wind tunnel testing and numerical simulation, a transition section is often used to connect the wind tunnel floor or computational domain bottom and the boundary top of the terrain model in order to generate a smooth flow transition over the edge of the terrain model. Although the transition section plays an important role in simulation of wind field over complex terrain, an appropriate shape needs investigation. In this study, two principles for selecting an appropriate shape of boundary transition section were proposed, and a theoretical curve serving for the mountain-gorge terrain model was derived based on potential flow theory around a circular cylinder. Then a two-dimensional (2-D) simulation was used to compare the flow transition performance between the proposed curved transition section and the traditional ramp transition section in a wind tunnel. Furthermore, the wind velocity field induced by the curved transition section with an equivalent slope of $30^{\circ}$ was investigated in detail, and a parameter called the 'velocity stability factor' was defined; an analytical model for predicting the velocity stability factor was also proposed. The results show that the proposed curved transition section has a better flow transition performance compared with the traditional ramp transition section. The proposed analytical model can also adequately predict the velocity stability factor of the wind field.

Numerical simulation of the neutral equilibrium atmospheric boundary layer using the SST k-ω turbulence model

Peng Hu,Yongle Li,C.S. Cai,Haili Liao,G.J. Xu 한국풍공학회 2013 한국풍공학회지 Vol.17 No.1

Modeling an equilibrium atmospheric boundary layer (ABL) in an empty computational domain has routinely been performed with the k-ε turbulence model. However, the research objects of structural wind engineering are bluff bodies, and the SST k-ω turbulence model is more widely used in the numerical simulation of flow around bluff bodies than the k-ε turbulence model. Therefore, to simulate an equilibrium ABL based on the SST k-ω turbulence model, the inlet profiles of the mean wind speed U, turbulence kinetic energy k, and specific dissipation rate ω are proposed, and the source terms for the U, k and ω are derived by satisfying their corresponding transport equations. Based on the proposed inlet profiles, numerical comparative studies with and without considering the source terms are carried out in an empty computational domain, and an actual numerical simulation with a trapezoidal hill is further conducted. It shows that when the source terms are considered, the profiles of U, k and ω are all maintained well along the empty computational domain and the accuracy of the actual numerical simulation is greatly improved. The present study could provide a new methodology for modeling the equilibrium ABL problem and for further CFD simulations with practical value.