Flow Field Analysis And Optimal Design Of Downhole Bionic Power Generation Device

With the continuous development of oil fields,the cost of crude oil production in China is increasing day by day.At present,waterflooding is adopted in the main oilfields in China,so stratified water injection is of great significance to the development of oilfields in China.With the development of stratified water injection development mode,the monitoring tool of downhole stratified water injection has been changed from mechanical to electronically controlled.However,the traditional underground power supply mode is easily limited by the complex environment in the wellbore,and there are some problems,such as the long-term sustainable power supply and the high cost of power supply.Inspired by the eel swinging body to generate electricity in the water,the downhole bionic power generation device can convert the continuous fluid mechanical energy in the wellbore into electrical energy,thus realizing the power supply for the downhole electric control tools.It is of great significance to the monitoring of stratified water injection in practical engineering application.In this paper,the suitable pipe diameter and bluff body size of underground bionic power generation device and the structural parameters of piezoelectric vibrator are optimized by orthogonal test method,and the optimal size combination of bluff body diameter and the best structural parameters of piezoelectric vibrator are obtained.At the same time,according to the distribution law of turbulent kinetic energy in the bluff body diameter combined flow field,a method for evaluating the turbulent kinetic energy excitation efficiency of the flow field with axial segmented radial stratification is proposed,and the orthogonal test results are verified.The flow field characteristics of the optimal size combination of bluff body diameter are studied by using CFD numerical simulation method and Fluent numerical simulation software.The distribution rules of velocity field,turbulent kinetic energy,turbulence intensity and kinetic energy dissipation rate in the flow field are analyzed.Using Workbench numerical simulation software,according to the distribution characteristics of the parameters in the flow field,the fluid-solid coupling between the fluid and the piezoelectric vibrator is studied,and the motion characteristics such as period and amplitude of the piezoelectric vibrator are obtained.The particle image velocimetry technology and high-speed camera technology are used to carry out laboratory experimental studies on the flow field characteristics and the motion characteristics of the piezoelectric vibrator.The comparison between the experimental data and the numerical simulation results shows that the two have a high degree of fit,which verifies the flow field characteristics and the motion characteristics of the piezoelectric vibrator obtained by the numerical simulation.In this paper,the structural parameters of the underground bionic power generation device are optimized,and the optimal combination of structural parameters is obtained.The flow field characteristics and motion characteristics of the downhole bionic power generation device under these structural parameters are studied,and the corresponding distribution law is obtained.It can be used as a reference for the practical engineering application of underground bionic power generation device.