Erosion Characteristics Analysis and Structure Optimization of Water Cap and Drive Shaft of Positive Displacement Motor
Positive displacement motor(PDM)is a widely used downhole dynamic drilling tool,its performance directly affects the drilling efficiency.The drive shaft and water cap in the structure are prone to fracture due to hydraulic erosion,which leads to the failure of PDM.Therefore,it is necessary to study the erosion characteristics of water cap and drive shaft.In this paper,based on computational fluid dynamics(CFD),a three-dimensional finite element model of water cap and drive shaft erosion was established to analyze the influence of the number of water cap diversion holes,equivalent diameter and inclination angle,and the structure of drive shaft hedge erosion,and to optimize its structure.The results show that the recommended water cap diversion angle of 45° is more suitable considering the erosion area and erosion rate.Increasing the number of diversion holes will increase the erosion area.It is recommended that the number of bypass holes should be 3.The erosion rate of the spline shaft increases with the increase of the groove width,and the arc section can effectively reduce the erosion.The outlet diameter of the drive shaft has little influence on its erosion rate.The results of this paper provide a theoretical basis for obtaining the erosion characteristics of water cap and drive shaft of PDM and optimizing the structure design.
NETL
NSTL
万方数据
