| As special equipment in the effective exploitation of the oil industry, submersible progressing cavity pump plays a key role in the transportation of the oilfield fixed wells, and has a wide application as well as high efficiency. But in actual oil field applications, leak oil and circumfluence, stator deformation, failure and other serious problems often arise, which affects the life span of the pump and reduces its properties and oil production. To improve the mechanical properties of screw pump, it is of practical significance to study the effect of the line profile, operation mode, deformation, wear of the stator cavity, and fluid movement in the stator cavity composed of the stator and rotor on the stator from the perspectives of oil production and the stator life span.Submersible screw pump consists of two main parts—the rotor and the stator. Its stator and rotor surface is complex and has a relatively special movement pattern. On the premise of considering increasing the flow rate and improving the lifespan, this paper conducts research on the three-thread single-screw pump with outer equidistant curve of curtate hypocycloid and inner equidistant curve of curtate epicycloids on the basis of contributions from other scholars, such as wall thickness of the stator and the hollow rotor technology. Three thread single-screw pump possesses advantages of a large delivery capacity, high efficiency, low energy consumption, and a good mechanical condition of the rotor, and is popularized gradually in the international market. In this paper, the molding principle of the end face of the three thread single screw pump is introduced, followed the deduction of the line type equations of the screw pump rotor and the stator. In addition, the formation mechanism of the sealed chamber is described, and then the movement disciplines of the rotor in the stator bushing and the movement of fluid in the sealed chamber are analyzed from the point of view of the kinematics.Based on the basic principle, the numerical analysis software Matlab is used to analyze and draft the screw end the flow areas, the amplitude coefficients and sliding speeds of the three-thread single-screw pump of two line type—curtate hypocycloid and curtate epicycloids are compared and analyzed, which helps to find out that the flow area A is proportional with the amplitude coefficient k. The greater the flow area, the bigger the sliding speed. The finite element analysis software ANSYS is employed to make a structor static analysis of the screw pump stator rubber and a contact analysis of the stator and rotor, which helps to study the deformation discipline of the inner contour of the stator rubber and the stress and strain distribution. Deformation of the stator rubber and force changes caused by uniform internal pressure, work non-uniform pressure and contact of the stator and rotor are also studied. the three-dimensional modeling software Pro / E is applied to conduct parametric solid modeling on the screw rotor and stator, and the movement trajectory as well as forces borne in the sealed fluid chamber and the rotor cavity under pressure are analyzed. Finally, based on results of the analysis, under the conditions of uniform pressure, the existence of interference and non-uniform pressure, the performance parameters of outer equidistant curve of curtate hypocycloid three-thread single-screw pump outweigh those of inner equidistant curve of curtate epicycloids three-thread single-screw pump, indicating that the screw pump with the optimized node is greatly improved in the flow rate and performance. |
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