Study On The Turbine Parametric Design For MWD Downhole Generator

With the continuous development of petroleum exploration technology,LWD and MWD technology plays a more and more important role,so the matched power supply system are put forward higher requirements.Compared with the traditional lithium-ion batteries,downhole mud turbine power generation system has a high temperature resistant,big output power,long life and other advantages,is widely used in engineering.Besides these excellent characteristics,the hydraulic performance is even more crucial,which is directly related to generation efficiency.Energy conversion efficiency of turbine is closely related to the structure and shape of the blade grid.From the structure and shape optimization of turbine blade grid to improve turbine energy conversion efficiency,is an effective way to obtain effective downhole turbines,which has high application value and engineering significance.Improve the hydraulic performance of turbine blade grid is the core of turbomachinery design.Traditional blade grid design method is complicated with long design cycle,and it is difficult to change the design after completion.It’s unable to realize local adjustment,the turbine efficiency is not ideal In this paper,on the basis of the turbine unigram flow theory,introduction NURBS curve as a turbine blade type line,use the idea of parametric design,put forward a new blowdown turbine blade profile design method.The method using NURBS curve characteristics of dual control with points and weight factor,implements local control of the turbine blade type line,improve the control flexibility,shorten the design cycle,improve the modeling efficiency and the accuracy of the model data.According to a certain MWDS instruments generator turbine performance requirements.Based on the working principle of downhole turbine generator and the turbine internal unigram flow theory,design turbine geometry structure and calculate the parameters of turbine blade grid.Under the same conditions,based on SoildWorks engineering modeling environment,use both NURBS curve profile and five order polynomial curve profile,set up two sets of three dimensional model of turbine.Application of the theory of computational fluid dynamics simulation two groups of the turbine,obtain the internal flow field characteristics and energy conversion efficiency.The result shows that the NURBS curve turbine overall hydraulic performance is better.Comparative analysis the five order polynomial blade turbine prototype bench test performance and simulation results,high degree of agreement,verify the correctness of turbine 3d modeling and simulation method in this paper.At the same time,it suggests the NURBS curve parametric design method is effective and correct.This paper presents a blowdown turbine blade profile parameterization design method based on NURBS curve.Combination of turbine unigram flow theory and parameterized design method,implements local control of the turbine blade type line and dynamic design.This research provides a new method for downhole high efficient generator turbine blade grid structure and shape optimization.