Study On Bionic Control Method Of Micro-pressure Wave At Exit Of High-speed Railway Tunnel

The peak value of the micro-pressure wave generated by the high-speed train passing through the tunnel is directly proportional to the third power of train speed.When the "higher speed" train passes through the tunnel,the micro-pressure wave is further intensified,causing violent burst at the tunnel exit,resulting in severe noise pollution,the resulting impact pressure damages the tunnel building structure and seriously affects the normal life of residents around the tunnel mouth.It is urgent to explore the significant mitigation method of micro-pressure wave under the condition of "higher speed".The traditional cross-section enlarged tunnel portal and inclined cut tunnel portal face the problems of large floor area and limited mitigation effect respectively.The root of inducing micropressure wave is the evolution of vehicle/tunnel coupled flow field.Therefore,expanding and combining advanced flow control technology is necessary to build a multi-disciplinary vehicle/tunnel coupled flow control method to mitigate micro-pressure wave significantly.Thus,this thesis constructs a tunnel micro-pressure wave control method based on bionic flow control,explores the influence mechanism and law of the critical aerodynamic parameters of shark gill and intestinal fold characteristics on the micro-pressure wave,defines the optimal bionic structural parameters,and realizes the further mitigation of the micro-pressure wave by coupling the two bionic tunnel portals.The main research contents and results of this thesis are as follows:(1)The overlapping grid numerical simulation method of vehicle/tunnel flow field coupled with multi-scale aerodynamic shape parameters is defined.The flow field simulation model of small and medium-scale bionic structure coupled with large-scale tunnel and train is established,the overlapping grid matching method under multi-scale conditions is proved,and the flow field based on SST K-ω,the corresponding parameter setting of DDES calculation method of turbulence model.The reliability of the calculation method in this thesis is verified by using the aerodynamic model test,and the maximum error is no more than 5.17%.(2)Through the observation and analysis of the shark parotid structure,the main geometric parameters of the imitation shark parotid opening buffer structure were determined,and the effects of the opening buffer structure of the opening ratio,oblique angle,opening height and opening distribution on the initial compression wave gradient and the micropressure wave amplitude of the tunnel exit were analyzed.It is determined that the optimal opening ratio of bionic hole is 24%,the oblique opening angle is 16°,the opening height is 0.25 H,and the opening distribution rate is 0.95.The mitigation rate of micro-pressure wave at the tunnel outlet by the optimal bionic shark cheek buffer structure is 51.3%.(3)The influence of large-scale intestinal fold structure on the micropressure wave at the tunnel outlet is clarified.Combined with the requirements of flow block and energy consumption,the shape characteristics of the intestinal fold are analyzed,the tunnel portal model of large-scale intestinal fold structure is constructed,the influence mechanism of fold width and depth on the surrounding flow field structure is analyzed,and its influence law on the initial compression wave and compression wave gradient is obtained.The research results show that matching intestinal fold width and depth parameters can alleviate the micro-pressure wave at the tunnel outlet to a certain extent,and the net relief rate is more than 2.73%.(4)The optimal matching model of bionic shark gill characteristics and intestinal fold characteristics is constructed.The matching scheme of bionic shark gill features and intestinal fold features is proposed,the influence law of matching parameters on the micro-pressure wave at the tunnel outlet is explored,the optimization model based on the optimal parameter matching of two bionic structures is constructed,and the influence mechanism of the optimization model on the initial compression wave and the gradient of the initial compression wave is analyzed.The results show that the relief rate of micro-pressure wave amplitude at the exit of the tunnel can reach 65.9% only by using the bionic portal with the characteristics of an imitation shark and intestinal fold.