In recent years,the safety and comfort of road vehicles driving on bridges under crosswinds have attracted more attention due to frequent occurrences of wind-induced disasters.This study focuses on a container truck a...In recent years,the safety and comfort of road vehicles driving on bridges under crosswinds have attracted more attention due to frequent occurrences of wind-induced disasters.This study focuses on a container truck and CRH2 high-speed train as research targets.Wind tunnel experiments are performed to investigate shielding effects of trains on aerodynamic characteristics of trucks.The results show that aerodynamic interference between trains and trucks varies with positions of trains(upstream,downstream)and trucks(upwind,downwind)and numbers of trains.To summarize,whether the train is upstream or downstream of tracks has basically no effect on aerodynamic forces,other than moments,of a truck driving on windward sides of bridges(upwind).In contrast,the presence of trains on the bridge deck has a significant impact on aerodynamic characteristics of a truck driving on leeward sides(downwind)at the same time.The best shielding effect on lateral forces of trucks occurs when the train is located downstream of tracks.Finally,the pressure measuring system shows that only lift forces on trains are affected by trucks,while other forces and moments are primarily affected by adjacent trains.展开更多
Wind barriers are commonly adopted to prevent the effects of wind on high-speed railway trains,but their wind-proofing effects are greatly affected by substructures.To investigate the effects of wind barriers on the a...Wind barriers are commonly adopted to prevent the effects of wind on high-speed railway trains,but their wind-proofing effects are greatly affected by substructures.To investigate the effects of wind barriers on the aerodynamic characteristic of road-rail same-story truss bridge-train systems,wind tunnel experiments were carried out using a 1:50 scale model.Taking a wind barrier with a porosity of 30%as an example,the aerodynamic characteristics of the bridge train system under different wind barrier layouts(single-sided and double-sided),positions(inside and outside)and heights(2.5 m,3.0 m,3.5 m and 4.0 m)were tested.The results indicate that the downstream inside wind barrier has almost no effect on the aerodynamic characteristics of the train-bridge system,but the downstream outside wind barrier increases the drag coefficient of the bridge and reduces both the lift coefficient and drag coefficient of the train due to its effect on the trains wind pressure distribution,especially on the trains leeward surface.When the wind barriers are arranged on the outside,their effects on the drag coefficient of the bridge and shielding effect on the train are greater than when they are arranged on the inside.As the height of the wind barrier increases,the drag coefficient of the bridge also gradually increases,and the lift coefficient and drag coefficient of the train gradually decrease,but the degree of variation of the aerodynamic coefficient with the height is slightly different due to the different wind barrier layouts.When 3.0 m high double-sided wind barriers are arranged on the outside of the truss bridge,the drag coefficient of the bridge only increases by 12%,while the drag coefficient of the train decreases by 55%.展开更多
基金Projects(52078504,51822803,51925808,U1934209)supported by the National Natural Science Foundation of ChinaProject(KF2021-05)supported by the State Key Laboratory of Mechanical Behavior and System Safety of Traffic Engineering Structures,China。
文摘In recent years,the safety and comfort of road vehicles driving on bridges under crosswinds have attracted more attention due to frequent occurrences of wind-induced disasters.This study focuses on a container truck and CRH2 high-speed train as research targets.Wind tunnel experiments are performed to investigate shielding effects of trains on aerodynamic characteristics of trucks.The results show that aerodynamic interference between trains and trucks varies with positions of trains(upstream,downstream)and trucks(upwind,downwind)and numbers of trains.To summarize,whether the train is upstream or downstream of tracks has basically no effect on aerodynamic forces,other than moments,of a truck driving on windward sides of bridges(upwind).In contrast,the presence of trains on the bridge deck has a significant impact on aerodynamic characteristics of a truck driving on leeward sides(downwind)at the same time.The best shielding effect on lateral forces of trucks occurs when the train is located downstream of tracks.Finally,the pressure measuring system shows that only lift forces on trains are affected by trucks,while other forces and moments are primarily affected by adjacent trains.
基金Projects(52078504,51822803,51925808) supported by the National Natural Science Foundation of ChinaProject(2021RC3016) supported by the Science and Technology Innovation Program of Hunan Province,China。
文摘Wind barriers are commonly adopted to prevent the effects of wind on high-speed railway trains,but their wind-proofing effects are greatly affected by substructures.To investigate the effects of wind barriers on the aerodynamic characteristic of road-rail same-story truss bridge-train systems,wind tunnel experiments were carried out using a 1:50 scale model.Taking a wind barrier with a porosity of 30%as an example,the aerodynamic characteristics of the bridge train system under different wind barrier layouts(single-sided and double-sided),positions(inside and outside)and heights(2.5 m,3.0 m,3.5 m and 4.0 m)were tested.The results indicate that the downstream inside wind barrier has almost no effect on the aerodynamic characteristics of the train-bridge system,but the downstream outside wind barrier increases the drag coefficient of the bridge and reduces both the lift coefficient and drag coefficient of the train due to its effect on the trains wind pressure distribution,especially on the trains leeward surface.When the wind barriers are arranged on the outside,their effects on the drag coefficient of the bridge and shielding effect on the train are greater than when they are arranged on the inside.As the height of the wind barrier increases,the drag coefficient of the bridge also gradually increases,and the lift coefficient and drag coefficient of the train gradually decrease,but the degree of variation of the aerodynamic coefficient with the height is slightly different due to the different wind barrier layouts.When 3.0 m high double-sided wind barriers are arranged on the outside of the truss bridge,the drag coefficient of the bridge only increases by 12%,while the drag coefficient of the train decreases by 55%.
