Study On Vacuum Design And Aerodynamic Characteristics Optimization Of Pipeline Transportation System

At present,the research of pipeline transportation system mainly focuses on speed realization,train aerodynamic characteristics and thermodynamics,and the system research is still in the 100-meter test stage.The realization of pipeline environment only uses the vacuum pump for the purpose of pumping the required pressure,and there is still a lack of large-cavity pipeline pumping and vacuum maintenance technical solutions.The purpose of this paper is to build a low vacuum environment of large size pipeline,and study the vacuum construction technology of pipeline traffic system,such as vacuum demand,pumping scheme,vacuum pump parameters and selection combination,and finally to simulate analysis and optimization of pneumatic characteristics of pumping pipeline.In this paper,the internal environment of pipeline transportation system is taken as the research object.Firstly,the vacuum demand of pipeline is analyzed from the aspects of design speed,vacuum adaptability of equipment and personnel inside and outside the vehicle,traction energy consumption and so on.Then,by analyzing the practical application and the vehicle size parameters of Datong test line,a calculation model of 1000 km in length and 4m in diameter is established for the traffic pipeline,and the relationship between the time required for vacuuming,energy consumption and the number of pumps and the distance between stations under the three purposes of pressure is studied.Then,according to the vacuum degree control index of Datong pipeline maglev traffic test line of 1k Pa～101k Pa,the pumping scheme of vacuum pump station is designed,which realizes the requirement of pipeline vacuum establishment time less than 4h.Finally,the ultimate pressure,pumping rate and power cost of the pump are compared and analyzed to complete the vacuum pump parameters and combination selection.Finally,based on the Reynolds number formula,combined with the aerodynamic formula,the gas flow rate formula and the pumping rate relationship,the relationship between the required working pressure of the pipeline traffic system and the gas flow state under different pipe diameters and the pumping rate of the vacuum pump was deduced,and its criterion was determined.Then,taking the air pump group on a test line of Hyperloop Company in the United States as the optimization prototype,combined with the analysis of the flow field characteristics in the pipe and the aerodynamic characteristics in the vacuum process in Chapter 2,the finite element analysis software Fluent was used to establish the three-dimensional continuous,viscous,incompressible and turbulent simulation model between the pipe,air and vacuum pump.After that,a variety of comparison models were established for the section area of the pumping pipeline,the access form of the vacuum pump and the interface structure to simulate the calculation,the change of air velocity and pressure distribution in the pipeline during the pumping process,and the optimization model of the pump group pipeline was designed.