Field Test Research Of Dynamic Air-tightness Of Emus On Steep Slopes High-speed Railways In Mountainous Areas

Railway is an important industry for national development.A strong railway network connects the country’s commerce and trade and connects regional economic development.Developed countries such as Europe and the United States have vigorously built railway systems since the last century,and now they have built a complete railway network,which can effectively support the development needs of the country,whether it is passenger or freight transport.In the 21 st century,my country has begun to vigorously develop the railway system,forming a high-speed railway system that integrates high-tech content,energy-saving and consumption-reducing characteristics.My country’s mountainous area accounts for 74% of the country’s total land area,and the western region accounts for a larger proportion.The major cities in the western region are isolated by mountains and inconvenient transportation.The construction and research of highspeed railways in mountainous areas has become very important.In order to study the dynamic air-tightness changes of EMUs,China National Railway Group Co.,Ltd.issued a scientific and technological research and development plan,in which the research on the air-tightness changes of passenger compartments of EMUs will be part of the research team.It can be seen that the reported foreign studies and experiments are all aimed at newly-built trains,and there are no public reports about the research on the airtight performance changes of EMUs under different operating mileage.The research on the air tightness of domestic EMUs started late.The results mainly focus on the problem of ear comfort and the static test of the whole vehicle on the ground,while the equivalent leakage area,dynamic air tightness and deterioration of air tightness of operating trains have been studied less.In this study,the Xi’an-Hanzhong section of the Xi’an-Chengdu Passenger Dedicated Line was selected as the test line.The train traverses the Qinling Mountains.It is the passengerdedicated high-speed railway line with the largest elevation jump and the steepest slope among the completed lines in China.The airtightness of the train passenger compartment is affected by the superimposition of the pressure wave of the tunnel and the atmospheric pressure change caused by the altitude change.This research is based on the actual vehicle test,focusing on the core factors and key technical issues of the air tightness change of the passenger compartment of the EMU to carry out the following research work:(1)Based on the test requirements and test environment,set up a reasonable test plan;combine the test train’s travel plan and test line characteristics to arrange measuring points that meet the requirements of the train’s two-way running up and down;according to the complex conditions of the test environment,sensor placement The method has been improved to enhance the anti-interference ability of the test system;the test plan has been improved,and on-site calibration test steps have been added,so that the measured pressure difference between the inside and outside of the vehicle can accurately reflect the real changes in the pressure inside the vehicle;taking into account the high altitude of the line Due to the characteristics of the drop,the air-conditioning system is closed during the test,and the compartment becomes a relatively closed area,which can better meet the requirements of the air tightness test.(2)Considering the experimental factors,we have researched and formulated an efficient and accurate test method for the pressure change inside and outside the vehicle;the airtightness research is carried out in the tunnel unit,and there is no universally recognized method for the pressure treatment method of the inside and outside of the tunnel at the entrance of the tunnel.This article combines the characteristics of the line Compared with the test requirements,the similarities and differences between maintaining the real pressure difference and eliminating the pressure difference were analyzed and compared,and proved the rationality of maintaining the pressure difference;(3)In the data analysis stage,combined with the characteristics of the pressure wave of the train passing through the tunnel,the data was filtered to make the data as smooth as possible without affecting the waveform change;after analyzing and comparing the analysis methods of other research teams,we obtained A set of accurate and reasonable air-tightness evaluation methods has greatly improved the accuracy of air-tightness evaluation;and two criteria for judging the accuracy of air-tightness have been proposed.(4)Analyze and compare the relationship between car body air tightness and train operating environment;analyze the relationship between different length tunnels and train air tightness in combination with train operation environment and status,and conclude that the train car body air tightness increases with the increase of tunnel length The characteristics are in line with the law of pressure wave attenuation in the tunnel.Considering the change law of airtightness when different train cars pass through the same tunnel,it is found that the airtightness change law of each compartment of the train is different in the uphill state and the downhill state.The size of the air tightness is related to the pressure difference inside and outside the vehicle,and the pressure difference is more atmospheric.The greater the tightness;the stiffness coefficient of the car body is calculated to be 0.05 based on the analysis of the test data.