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
The aerodynamic performances of a passenger car and a box car with different heights of windbreak walls under strong wind were studied using the numerical simulations, and the changes of aerodynamic side force, lift f...The aerodynamic performances of a passenger car and a box car with different heights of windbreak walls under strong wind were studied using the numerical simulations, and the changes of aerodynamic side force, lift force and overturning moment with different wind speeds and wall heights were calculated. According to the principle of static moment balance of vehicles, the overturning coefficients of trains with different wind speeds and wall heights were obtained. Based on the influence of wind speed and wall height on the aerodynamic performance and the overturning stability of trains, a method of determination of the load balance ranges for the train operation safety was proposed, which made the overturning coefficient have nearly closed interval. A min(|A1|+|A2|), s.t. |A1|→|A2|(A1 refers to the downwind overturning coefficient and A2 refers to the upwind overturning coefficient)was found. This minimum value helps to lower the wall height as much as possible, and meanwhile, guarantees the operation safety of various types of trains under strong wind. This method has been used for the construction and improvement of the windbreak walls along the Lanzhou–Xinjiang railway(from Lanzhou to Urumqi, China).展开更多
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%.
基金Project(U1334203) supported by the National Natural Science Foundation of China
文摘The aerodynamic performances of a passenger car and a box car with different heights of windbreak walls under strong wind were studied using the numerical simulations, and the changes of aerodynamic side force, lift force and overturning moment with different wind speeds and wall heights were calculated. According to the principle of static moment balance of vehicles, the overturning coefficients of trains with different wind speeds and wall heights were obtained. Based on the influence of wind speed and wall height on the aerodynamic performance and the overturning stability of trains, a method of determination of the load balance ranges for the train operation safety was proposed, which made the overturning coefficient have nearly closed interval. A min(|A1|+|A2|), s.t. |A1|→|A2|(A1 refers to the downwind overturning coefficient and A2 refers to the upwind overturning coefficient)was found. This minimum value helps to lower the wall height as much as possible, and meanwhile, guarantees the operation safety of various types of trains under strong wind. This method has been used for the construction and improvement of the windbreak walls along the Lanzhou–Xinjiang railway(from Lanzhou to Urumqi, China).
