钻井泵活塞缸套密封系统密封性能流-固耦合分析

Fluid-Solid Coupling Analysis of Sealing Performance of Drilling Pump Piston-Liner Sealing System

现有的关于钻井泵活塞皮碗受力情况的相关研究,大多忽略了钻井泵工作过程中活塞缸套与钻井液的流-固耦合作用,得出的结论与实际的受力特性有一定的差别。为研究活塞皮碗的受力情况,通过建立活塞缸套的有限元模型,采用流-固耦合方法来模拟活塞缸套受力特性,同时探讨皮碗过盈量以及唇角尺寸对其密封性能的影响。仿真结果表明:缸套与皮碗接触面之间受力变化规律与缸套内压力变化规律相似;在最大工作压力作用下,缸套内表面和垫圈表面与皮碗接触部位等效应力都较大,但相较于缸套和垫圈,皮碗是活塞密封中最易失效的部件;皮碗的应力主要集中在活塞皮碗的唇部及根部与垫圈接触处,而这也是皮碗易发生失效的2个部位;当皮碗过盈量大于1.0 mm,唇角大于15°时,皮碗唇部会产生向心效应,进而影响皮碗的密封性能。

Most of the existing researches on the stress of the piston cups of drilling pumps neglect the fluid solid coupling between the piston liners and the drilling fluid during the working process of the drilling pump,and the conclusions drawn are different from the actual stress characteristics.In order to study the stress condition of the piston cup in the process of movement,the finite element model of the piston cylinder liner was established,and the mechanical characteristics of piston-liner were numerically simulated by fluid-structure coupling method.The effects of changing cup interference and lip angle size on the sealing performance of the piston-liner were discussed.The results show that the change rule of stress between the contact surface of the cylinder liner and the leather cup is similar to the change law of pressure inside the cylinder liner.Under the maximum working pressure,the equivalent stresses on the inner surface of the cylinder liner and the surface of the gasket in contact with the cup are relatively large,but compared to the cylinder liner and gasket,the cup is the most vulnerable part of the piston seal.The stress of the leather cup is mainly concentrated on the contact between the lip and root of the piston cup and the gasket,which are also two places where the leather cup is prone to failure.When the interference of the leather cup is greater than 1.0 mm and the lip angle is greater than 15°,the lip of the cup will produce a centripetal effect,which will affect the sealing performance of the cup.