Three-Dimensional Cascade Design And Simulation Of Small Size Turbodrill

Coiled tubing technology is widely used in the oil drilling field,which can greatly reduce the cost of drilling operations.However,it is inevitable that the production string will be clogged for a long time.Due to the small diameter of the string,it is urgent to design a small size turbodrill to solve the plugging work.Domestic scholars have made a lot of exploration on turbodrill,but the research on small size turbodrill is not in-depth.In addition,domestic research mainly focuses on the modeling method of turbine blade profile,while ignoring the overall modeling of turbine cascade.According to the threedimensional design theory of pneumatic turbines,three-dimensional cascade is more conducive to fluid work.In this paper,a small size turbodrill 3D cascade is designed and the performance of the 3D cascade turbine is evaluated.In this paper,the basic parameters of the turbine are determined through the benchmarking design with the small-size turbine of Neyrfor Company,and then the blade parameters of the blade root section are calculated.Then,based on the straight blade design theory,the three-dimensional blade modeling method with multiple sections and constant loop distortion is explored to determine the parameters of other sections.Aiming at the minimum curvature change of blade profile,the profile modeling method was optimized.Finally,it was determined to use quintic polynomial for blade modeling,and parametric modeling was used to complete the establishment of turbine stator,rotor and flow channel modelsCFX software was used to carry out hydraulic simulation calculation on the flow channel model of a single stage turbine,and the distribution of turbine velocity field and pressure field and turbine characteristic curve at different speeds were obtained.Then,the comparative analysis of the performance of 3D cascade turbines and straight cascade turbines shows that the output torque of 3D cascade turbines is slightly lower than that of straight cascade turbines,but the efficiency of 3D cascade turbines is about 10% higher than that of straight cascade turbines.Then,the pressure field and velocity field at the root,middle and tip sections of two kinds of turbine blades are analyzed respectively,and the differences between them are obtained and explained.With turbine output torque,pressure drop and efficiency as test indexes,turbine stator,rotor blade root section inlet structural Angle,outlet structural Angle,leading edge wedge Angle,trailing edge wedge Angle and leading edge radius as test factors,orthogonal tests were carried out to optimize turbine design.By conducting range analysis and variance analysis on the test results,the influence degree of each factor on the test index is obtained.Based on this,the optimization of factor level is carried out to complete the optimization of turbine blade parameters.The optimized turbine model was established and the simulation analysis was carried out.The results showed that compared with the pre-optimized turbine,the optimized turbine torque increased by 5% at2500r/min,the efficiency increased by 4%,and the hydraulic performance improved a lot.Based on the optimized turbine model,the influences of radial clearance and drilling fluid characteristics on turbine performance parameters were explored.By analyzing the simulation results,the influences of drilling fluid flow,density and viscosity on turbine performance parameters were summarized.