Research On Characteristics Of Seal And Cavitation Of Miniature Ultra-high Pressure Single-piston Pump

As the power source of hydraulic system-hydraulic pump, its leakage is about 7.5 percent of the total leakage of hydraulic system, not only affecting the volumetric efficiency of hydraulic pump, reducing the pump's work life, resulting in waste of resources, and even causing environmental pollution. Therefore, the anti-leak of the hydraulic pump is particularly important. Cavitation is one of the most common and important noise-induced factors in hydraulic components, it will lower the efficiency of hydraulic pumps, damage parts, shorten the life of hydraulic components and pipes, cause the pulsation of flow and pressure. Therefore, in order to design hydraulic pump of low leakage and low cavitation, research on the problem of seal and cavitation is very important.The main content of this thesis:In chapter 1, the purpose and significance of this thesis is presented. The history and current research progress on seal and cavitation of piston pump are reviewed. Lastly, the technology of fluid-structure interaction and theory of multiphase flow are briefly presented in this thesis.In chapter 2, the reciprocating seal theory of hydraulic plunger involved in numerical simulation of fluid-structure interaction in single-piston pump and the bubble dynamics involved in numerical simulation of cavitation flow field are briefly presented.In chapter 3, the co-simulation of ANSYS Workbench and CFX software is used in reciprocating seal problem of single-piston, a typical fluid-structure interaction problem. The conclusions of different pressure distribution of seal gap, leakage, radial displacement distribution of seal gap in different pressures are also gotten. In the aspect of experiment, leakages in plunger chamber are compared by using two different test devices of non o-ring and o-ring. By comparison of the results of numerical simulation and experiment study, the leakages of the plunger chamber in numerical simulation and in the experiment study are consistent, indicating that the fluid-structure interaction simulation model is valid. In chapter 4, the numerical simulation of cavitation flow field in the working chamber of piston pump is implemented by Fluent software. The non-equilibrium wall functionκ-εmodel and multiphase flow mixed model with cavitation effect are carried out, the law of cavitation flow field in the working chamber of piston pump with different valve openings and inlet speeds obtained. In the aspect of experiment study, the vacuum in the working chamber of piston pump is compared by two different experiment devices of non-slippage pump and slippage pump. By comparison of the results of numerical simulation and experiment study, the vacuum in the plunger chamber in numerical simulation and in the experiment study is consistent, the law of cavitation flow field in the working chamber of piston pump can be predicted by the non-equilibrium wall functionκ-εmodel and multiphase flow mixed model with cavitation effect.In chapter 5, some conclusions in this thesis are summarized and the future research proposals are suggested.