Design And Research Of Three-dimensional Blades Of Turbodrills

As the primary power plant in the petroleum industry,the turbine drilling tool took off and emerged as the downhole power drilling tool during the 1980s because of the nation’s desire for oil resource exploitation and industrial development,which became known as the screw drilling tool.Both of them are three major technologies on the development track of the oil industry.The reason why a significant breakthrough appears in the development of turbine drilling tools is that the exploitation of conventional strata resources is nearing completion and the new wave of oil and gas exploitation has been centered on unconventional oil and gas resources with complex stratigraphic environment,especially in the harsh environment such as deep wells and high temperature and high pressure.Although the screw drilling equipment has superior drilling performance,its disadvantages are also obvious such as the large vibration and the instability,which cause an inevitable inadaptability in these areas.The turbine drilling tool,possessing the characteristics of high rotation speed,low vibration,and high temperature resistance,works well in all kind of geological conditions.Now the great deals of explorations have been conducted on turbine drilling tools.At the same time large amount of work has also achieved fruitful results in the design and research of turbine straight blades.This paper has found that the three-dimensional design theory of pneumatic turbines can more accurately reveal the actual flow field inside the turbine drilling tool compared with the straightforward blade design theory during the research on domestic and foreign turbine research.Based on this point,this paper presents a set of design theory and modeling analysis methods that can be applied to the three-dimensional blades of turbine drilling tools.The specific research contents are as follows:(1)Research on three-dimensional design theory of turbine bladesStudying the three-dimensional design theory of pneumatic turbines is based on the design of long blades.In the process of designing the long blades,a variation of blade parameters in the radial direction is considered,and the average diameter of the turbine blades and the height of the blades of the stator are taken into account.The ratio is less than 7～10 and belongs to the category of long blade design.In addition,the axial flow turbines’aerodynamic calculation belongs to the ternary steady flow problem.It is simplified to solve the simple radial equilibrium equation by several hypotheses,and the three-dimensional design theory,named Equal loop method,is presented.The turbine drilling tool also satisfies the prerequisite assumptions made in the simplification of the problem,thus verifying the feasibility of the three-dimensional design theory applying to the design of turbine drilling tool blades.(2)Parameters designThe rotor blades are equally divided into five sections in the radial direction.The root section parameters of the blades are first calculated according to the working condition parameters.Then the equivalent loop distortion calculation method was used to calculate the remaining four sections based on the root section parameters.(3)Blade shapeThree-dimensional blades are modeled in the NUMECA software’s AUTOBLADE module.Having inputted or selected the end wall profile,flow surface type,blade cross-section parameters,stacking law and homepage slice type and checked the structure and shape of the three-dimensional model,the text is going to prepare for numerical simulation analysis.(4)Flow field simulation analysis of turbine stator and rotor bladesAfter the 3D models are generated,they will be meshed by using the Autogrid5 module in NUMECA software.Subsequently the quality of the grid will be detected and a qualified calculation model could be obtained.Importing the grid model into the CFX software for flow field simulation analysis,the simulation cloud diagrams and the turbine performance curves at different speeds could be conducted.From the turbine performance curves diagram,we will find an optimum drilling speed that the stator and rotors with this type of profiles are of superior performance.(5)Three-dimensional blade optimization and performance amelioratingThe stacking laws and the modeling patterns of the primary blade in the three-dimensional blades’ forming methods are optimized,Having analyzed the different types of forming modes of three-dimensional blade with numerical,a better forming method which is of high performance will be selected according to the flow field simulation results.In addition,the parameters of axial chord length,number of stator blades,and axial clearance are researched and analyzed,at the same time Three-dimensional blade models with different parameters are simulated within their respective parameter ranges,and parameter values that could improve performance are selected based on the performance trend chart,thus making the blade performance improve.