Research On The Numerical Simulation Of The Velocity Of The Concentric Annular Gap Spiral Flow Around The Stationary Column In The Horizontal Straight Pipeline

As a new method of transportation,the hydraulic pipeline transportation of tube loading not only has the advantages of no pollution,low energy consumption,small footprint and transportation concealment,so that alleviates the problems brought by the traditional transportation mode,such as high energy consumption,higher emission,serious pollution and so on,but also,to a certain extent,the hydraulic pipeline transportation of tube loading alleviates the transportation pressure of traditional transportation mode.This paper relies on the National Natural Science Foundation Project "Research on the energy consumption of hydraulic pipeline transportation of train(51179116)","the research on the hydraulic characteristics of the pipe crevice spiral flow(51109155)" and the Shanxi Natural Science Foundation Project "Research on the hydraulic characteristics of annular crevice spiral flow of the hydraulic pipeline transportation of tube loading(2015011067)",using the method of combining physical experiment with numerical simulation.Auto CAD is used to simulate the model of the pipe and the carriage.ICEM CFD is used to set up the grid,and the ANSYS FLUENT is used to carry on three-dimensional numerical simulation of the flow velocity under different geometrical parameters of the generalized column system.In this paper,five control factors,including diameter and length of the main cylinder and length,height and angle of guide strip,are selected to study the velocity characteristics of the flow around a stationary column system with different geometrical parameters.The results are as follows:(1)The axial velocity of upstream flow is affected by the upstream support and seal cover.The closer the seal cover is,the greater the flow change amplitude.The seal cover and the support form L-shaped structure so that the flow at the left end of the bulge on the seal cover gets a larger tangential velocity.(2)The annular crevice spiral flow is mainly affected by the upstream support,the sealing cover,the size of the guide strip in the annular gap,and the length and diameter of the main cylinder.The effect of the support body and the seal cover on the flow is mainly to block the flow and to form the tail vortex in the subsequent annular basin.The larger the diameter of the main cylinder,the smaller the effect of the tail vortex to the annular flow.The main function of the guide strip is to transform the axial velocity into the tangential velocity,and the flow of water over the upstream surface of the guide strip will transform the axial velocity into the radial velocity and the tangential velocity,and the swirling flow is formed on the downstream surface of the guide strip.The axial velocity decreases along the flow direction of the guide strip,and the tangential and radial velocity increases obviously.The amplitude of the three dimensional velocity of the upstream and downstream surface is positively related to the angle and height of the guide strip and the diameter of the main cylinder.It is negatively related to the length of the guide strip and the length of the main cylinder.(3)The downstream flow of the column system is mainly affected by the guide strip,the size of the main cylinder,the downstream support and the sealing cover.The farther the distance from the column system is,the smaller the downstream flow will be affected by the column system,and the flow pattern will be close to the full pipe flow without column system.The axial velocity of the middle axis of the column is reduced first and then increases,and the velocity tends to be stable after a certain distance,and the diameter of the main cylinder is obviously affected by the distance to the main cylinder.The larger the diameter of the main cylinder is,the greater the required distance is.The tangential velocity of the downstream central axis increases first and then decreases,the radial velocity increases first and then decreases then increases,and the tangential and radial velocity is greatly influenced by the support at the distance downstream seal cover 30 mm.The variation of tangential and radial velocity is positively related to the angle,height and length of the guide strip and the length and diameter of the main cylinder.The research results in this paper have important reference value for further studying the characteristics of helical flow velocity in pipeline column system.It has great significance to further explore the mechanism of flow change in pipeline carriage.It also provides a feasible modeling and meshing method for column numerical simulation.