Study On The Flow Field Of The Turbine Of Downhole Turbogenerator

The significance of directional well drilling and the positive importance of the directional drilling applying measuring with drilling (MWD) and LWD system to the oil resources acquisition are described briefly. Combined with the continuous wave mud pulse MWD system,the 2D profile design and 3D modelling of fish-like blade is proposed,then the 3D turbulent flow field analysis is carried out.The structure optimization and working characteristics research are completed.Internal flow field characteristics of the turbine is pointed out.The external characteristics of turbine generator is studied based on the generator ground test.The major research contents in this thesis are as follows:(1) Focused on the characteristic and applicaton of the underlying power supply-turbine generator, the characteristics of MWD and the main signal transmission models especially the mud pulse signal transmission model are introduced. The structure layout and the power generating of the turbine generator are described also.The optimization research of turbine-the key factor on the energy transfer-is carried out,which is important to improve generation efficiency.The reaearch method with practical meaning is proposed.(2) The fish-like blade profile is proposed based on the analysis of working environment,materials and structure form of the turbine.The modelling is completed using 3D engineering modelling software Pro/E, based on which the cascade whole flow passage of the turbine and the pulley are extracted.(3) On the basis of the knowledge of the turbine,its working characteristics theory is introduced.Then the CFD mathematical theory which is the basis solution idea of the FLUENT software applying to flow field simulation is introduced and the specific solution method for the problem of machinery with axial-flow impeller is presented.The field characteristics of the turbine are mainly studied through flow field numerical simulation.Through the flow characteristics analysis of the turbine model with different blade parameters,the blade structure is optimized,and the internal flow field characteristics are improved.The external characteristics of the turbine is presented through the simulation of the flow rate and rotation speed.(4) The external characteristics of the turbine generator, is studied based on the unidirectional hydraulic test which is carride out according to the relative standards and the underlying turbine generator working situation.The external characteristicts means the influences of turbine rotation speed, The numerical results are validated by comparing with the experimental results.Through the research work in the thesis,the modelling method of the turbine blade and the numerical simulation method applying CFD theory and corresponding software are understood.The structure optimization method of turbine is proposed.Based on the turbine generator hydraulic ground test,the influences of the working parameters on the generator power are investigated.The research results can provide theoretical guidance for the study of the blade of axial-flow machinery.