Study On The Action Mechanism Of Wind Sand Flow On The Windbreak Structure Of High Speed Railway And The Track Sand Accumulation

The Lanxin Railway is a high-speed railway connecting Gansu Province and Xinjiang in China.It has extremely important significance in railway transportation.It conducts research and analysis on the railway sand disasters that occur in the strong wind and sand areas it passes through.Based on the CFD method,this paper uses numerical simulation to analyze the process of the wind and sand flow passing through the windshields of different heights,study the leeward side flow field and response laws,conduct aerodynamic analysis,and pay attention to the problem of track sand accumulation.The main contents are as follows :(1)When the windshield is not installed,it can be obtained from the pressure cloud diagram of the windward and leeward sides of the train.The positive pressure range is mainly distributed on the windward side of the train,and the negative pressure range is mainly distributed on the leeward side of the train.There is a pressure difference on both sides.The possibility of the train overturning;after the windshield is laid,the wind speed profile diagram summarizes that the flow field velocity changes relatively smoothly at a distance from the embankment and the windshield wall and within a range of 0-5m from the ground;In the area above the windshield,about 5m ～ 10 m in height,the wind speed first increases exponentially,then gradually becomes gentle,and decreases slightly;at10m height,the fluctuation of wind speed is small,smooth and tending Yu stable.(2)On the line graph of overturning moment,it is analyzed that when the height of the windshield is low,the overturning moment is greater,and when the height of the windshield is higher,the overturning moment produced has a clear decreasing trend;with the initial environment As the wind speed increases,when the train runs at different speeds,the lateral force and lift force experienced by the train are increasing.Due to the pressure difference between the train and the environmental wind pressure difference,the overturning moment also increases.(3)Through the pressure cloud and streamline diagrams of the windshields with different heights,it can be obtained that the original positive pressure range is transferred from the windward side of the train to the windward side of the windshield due to the blocking protection of the windshield.When the pressure is reduced,the flow of the streamline changes roughly the same;eddy currents appear in the middle of the windshield and the train and on the right side of the train,and the external flow field is more complicated.(4)In the sand particle volume fraction cloud diagram,under lateral wind conditions and different initial wind speeds,the sand accumulation process has similarities,most of which are accumulated near the windward side of the windshield wall and the embankment surface,on the windward side The degree of sand accumulation is greater than that of the leeward side.In the embankment surface area,there is more sand near the middle and less distribution on both sides.(5)Within the range of 15 s,the movement of the vortex appears.First,it moves forward,the range expands,the airflow diffuses,and then the sand particles fall down and accumulate on the embankment.With time,the sand particles move to the right To expand,the extension is more obvious towards the leeward side of the embankment and on the ground.In areas with high wind speeds,more attention should be paid to the prevention of wind and sand damage.