Optimal Design And Research Of Turbine Drilling Blades Based On Response Surface Methodology

With the rapid development of the global economy, demand for energy continues to expand. Although many countries strive to develop new resources of energy, stratigraphic resources remain the mian energy in the contemporary society. Under the severe condition that production of oil and gas is difficult to significantly increase and consumption of oil and gas resources is in the rapid growth in conventional explorationis, the main field of oil and gas exploitation gradually shifts to deep and ultra deep field. Particularly, we are facing severe challenges in efficient and reliable drilling in the high temperature and high pressure complex formation. Turbodrill, as a downhole drill motor with high-temperature resistance and no rubber elements, has been paid much attention since the beginning of its application. Turbodrill can be matched with an efficient bit to work quickly with good deviation control and gentle pressure. As a result, it has been achieved good application in the deep and ultra deep wells. Turbine, as a core component of the turbodril, has a decisive influence on the performance of turbodrill. Turbine is composed of stators and rotors, of which the blades are shaped complicatedly and variously. Different profiles of blades determine the different performance of turbodrill. Thus, the design and optimization of blade profiles have an immeasurable role to improve the performance of turbodrill.However, the structural parameters of the turbine blades are up to a dozen, and there is a certain mutual relation among the parameters, which undoubtedly brings a big challenge in blade design. This project is for the turbine blade design complexity in the paper. Based on blade profile design theory, Computational Fluid Dynamics (CFD), experimental design methods and optimization algorithms, the design and simulation as well as optimization were first studied systematically by a large number of domestic and foreign literature research, theoretical analysis and experimental design, which formed a system from frofile design, performance prediction to optimization. Specific analysis and research methods are as follows:(1) Based on Bezier theory and turbomachinery theory, the profile design method of turbine blades was established. The blade profile design of 0127 turbodrill was taken for example. And this method was verified by blade-type curvature inspection and flow channel test;(2) Based on Bezier theory, three-dimensional modeling software and CFD technology, the method was established, which included the profile design,3D modeling and simulation. The performance of blades shaped by the thrid, fourth and fifth order Bezier curve was first studied systematically. Through analysis and calculation, the fifth order Bezier curve was selected to design the profile, which gave a foundation for the following research;(3) The effect of structural parameters of blades on the efficiency and torque of the turbine was studied, using orthogonal experimental design method. Combined with range analysis and trend analysis of the relationship between parameters and efficiency as well as torque, sequence and sensitivity of parameters affecting the performance of turbine were obtained. As a result, the main parameters of blades were determined, and their ranges also were ensured;(4) In this paper, the main structure parameters selected were refered to design variables. Efficiency and torque of turbine were regarded as optimization objectives. Through the method of Box-Behnken, the response surface models reflecting the relationship between variables and objectives were established. According to the coefficient of variation, correlation coefficient and multiple correlation coefficient, prediction-simulation distribution and normal probability distribution of residuals, the response surface models were assessed to to verify the feasibility;(5) The models obtained above were optimized by using the penalty function method. After the optimization, the optimum combination of parameters blades was obtained, and flow field and hydraulic properties were compared with the blades before optimization. The results indicated that the velocity distribution after optimization was improved, so that it effectively improved the working conditions of the turbine. Compared with the performance of the blades before optimization, the hydraulic performance of optimized turbine has been significantly improved, with efficiency increased by 2.13% from 0.563613 to 0.57559 and torque increased by 3.4902N-m from 4.95248N·m to 8.44266N-m eventually.