Research On Aerodynamic Characteristics And Parameter Sensitivity Analysis Of Annular Space During High-Speed Elevator Intersection

The rapid development of urban modernization has led to the gradual development of high-rise buildings,which has also brought attention and research to high-speed elevators.The high-speed operation of elevators can cause drastic changes in the airflow inside the hoistway,resulting in a series of problems such as wind induced vibration and aerodynamic noise.During the operation of high-speed elevators,the air in the hoistway is rapidly compressed and released,forming a piston effect.Especially when the car and counterweight intersect,the piston effect causes a sharp change in the aerodynamic force on both,affecting the stability of elevator operation.The flow field in the annular space between the car and the hoistway is an important component of the piston effect.It is particularly important to study the airflow movement law in the annular space and weaken the piston effect.This article studies the flow characteristics of airflow in the intersection process through three-dimensional numerical modeling and flow theory modeling,integrating numerical simulation methods.The feasibility of the numerical method and theoretical model is verified through physical experiments,providing certain theoretical guidance for the engineering application of airflow change analysis in the intersection process.Firstly,according to different parameter changes,several three-dimensional numerical models of high-speed elevator car-counterweight rendezvous are constructed.With full consideration of the coupling relationship between moving wall and static wall,based on the semi empirical theory of turbulence and Bernoulli principle,the theoretical model of air flow between high-speed elevator car and hoistway annulus is established,and the annular flow velocity distribution law and characteristic position are obtained;Then,a multi-region dynamic layered numerical method based on the intersection model is proposed to calculate the aerodynamic flow field in the whole motion process.A dynamic grid computing calculation method with different accuracy is proposed,and the finite volume method is used to solve the control equations,and the boundary conditions of the calculation region are defined.Secondly,based on the proposed three-dimensional numerical model of the rendezvous process and the annular space flow theory model,numerical simulations were conducted to study the changes in lateral force,circumferential pressure,and vertical drag of the car and counterweight during the rendezvous process.Furthermore,the variation law of unsteady airflow in the hoistway during the rendezvous period and the sudden changes in force on the car and counterweight were analyzed;For the annular space area of the hoistway and car,theoretical analysis was conducted on the annular flow field of the car at different operating times.At the same time,the variation of annular flow velocity with wall distance at different times was calculated,and the wall characteristic positions were obtained when the annular flow velocity was equal to the car operating speed,negative velocity was maximum,and equal to zero,respectively.Then,perform independence verification on three different precision dynamic grid numerical calculation models;The 120 m high speed elevator test tower of the cooperative elevator company is used to build the air flow test platform for the high-speed elevator rendezvous process.The GM8902 digital anemometer is used to test the air flow characteristics of the car during the rendezvous with the counterweight and measure the flow speed of the car hoistway annulus space.Then,the correlation analysis of the threedimensional simulation data and the test data is conducted,and the error is rationalized,Verified the effectiveness and authenticity of simulation calculations.Finally,based on the established numerical and theoretical models,a multi zone layered simulation calculation was conducted to study the changes in drag force and lateral force around the car body under four different blocking ratios,length ratios,and spacing changes.The influence of different structural parameter changes on the aerodynamic load and induced airflow during the intersection phase of the car and counterweight was compared and analyzed;Then,by changing nine groups of car speeds,six groups of car heights,six groups of car blockage ratios and six kinds of hoistway heights,the variation law of annular flow velocity with wall distance under different parameter changes is analyzed,and the influence of the above parameter changes on the distribution of air flow velocity in the hoistway car annular space is studied.It is obtained that when the car and counterweight meet in the hoistway,the interaction between the car and counterweight is enhanced,the drag force coefficient and lateral force coefficient of the car undergo sudden changes and return to normal state after intersection;As the length ratio and spacing decrease,as well as the blockage ratio increases,the degree of drag force mutation also increases.The lateral force mutation of the car is mainly affected by the weight spacing of the car and increases with the decrease of the spacing;For the hoistway car annulus region,the annulus flow velocity distribution shows a trend of first positive then negative and finally tends to zero with the increase of wall distance;The Characteristic velocity in the annular flow field is related to several factors;The most obvious influence on the annular flow velocity distribution is the car speed,followed by the hoistway blockage ratio and hoistway height.The change of car height has little influence on the annular flow velocity distribution.