Research On Ideal Shape Optimization Design Of Vacuum Pipeline Vehicles

With the popularization of high-speed transportation and the accelerated pace of life,people have higher and higher requirements for travel efficiency,and traditional travel methods can no longer meet the needs.It has the advantages of low energy consumption,safety and reliability,and has great research potential.For a vacuum pipeline vehicle running at high Mach,a good aerodynamic shape is an essential basic condition.Starting from the modeling of the vacuum pipeline vehicle,this paper designs an ideal shape with less aerodynamic resistance,and adopts the approximate model optimization method to optimize the ideal aerodynamic shape.Finally,the influence of the drag reducing rod on the aerodynamic performance of the vehicle is explored,which provides the reference for optimizing the shape of the vacuum pipeline vehicle.In this paper,referring to the aerodynamic modeling in the aerospace field,four longitudinal contour lines are designed.Then the two-dimensional model is established,the model is divided into two-dimensional meshes,the aerodynamic characteristics of the four two-dimensional models are analyzed.The wire has good aerodynamic resistance and pressure distribution,so the bullet-shaped contour is selected.Subsequently,this paper designs three horizontal contour lines and three horizontal contour lines,which are combined with the bullet-shaped contour lines,and nine kinds of head shapes are designed.The three-dimensional model constructed by the combination of vertical section,arch cross-section and linear horizontal section has the minimum aerodynamic resistance,so this model is selected as the ideal shape of the vacuum pipeline vehicle designed in this paper.Parametric modeling is carried out on the ideal shape,and 14 control points are designed to change the vehicle shape through the change of the position of the control points.Using the Latin hypercube sampling method,70 groups of sample points were randomly selected,and the geometric models corresponding to the 70 groups of sample points were simulated and analyzed,and the aerodynamic drag coefficient of each group was obtained.The radial basis neural network(RBF)is used to fit 70 sets of data to obtain an approximate model.The genetic algorithm is used to solve the approximate model,and the values of each parameter with the optimal aerodynamic performance are obtained.The optimization model is simulated and analyzed,and the drag reduction rate is 1.42%.Finally,this paper designs three different shapes of drag reducing rods,establishes three-dimensional model and conducts simulation analysis.It is found that the spherical drag reducing rod is the best,and the drag reduction rate is about 0.60%.The influence of the length,height and front-end sphere radius of the spherical drag reducing rod on the aerodynamic performance of the vehicle was analyzed.It was found that with the drag reducing rod length increases,the drag reducing effect of the drag reducing rod first increased and then decreased;with the height of the drag reducing rod increases,the drag reducing effect of the drag reducing rod first decreases and then increases;with the radius of the sphere at the front end of the drag reducing rod increases,the drag reduction effect of the drag reducing rod decreases.It provides the reference for the application of drag reducing rods on vacuum pipeline vehicles in the future.