CFD Analysis Of Dynamic Characteristics Of Flow Field During Distribution Process In Axial Piston Pump

Axial piston pump with its high overall efficiency, high robustness and high power density, is widely used in engineering application. With the hydraulic system oriented to the high speed, high pressure and great flow rate, it is demanded that pumps should be capable of even more excellent performance.This thesis explores the dynamic characteristics of flow field during flow distribution process in axial piston pump with the aid of CFD. The aim of the work is to establish a more accurate flow field model considering various factors and deeply understand all the phenomena involved in the flow distribution process. With the theoretical analysis and simulation methods, more realistic results could be achieved. It has some significance to the flow field studies and the structure design optimization of the axial piston pump.The main contents of this thesis can be summarized in the following aspects.The first chapter mainly introduces the background and significance of the research theme, including characteristics of axial piston pump and the existing researches adopting CFD in hydraulic components. And generally summarizes the research status of axial piston pump at home and abroad. At last, the significance and content of the thesis are presented.The second chapter focuses on the numerical simulation. According to Reynolds Number calculated, the flow regime inside the axial piston pump is laminar with some local disturbances of turbulent flow; the working medium in axial piston pump is weakly compressible fluid instead of incompressible fluid, the state equation of weakly compressible fluid is developed; The other concern is the influence of the variation of viscosity, the viscosity function which is temperature and pressure dependent is adopted. These two equations above are supplied to the governing equations. The governing equations are closed and then sloved numerically.The third chapter investigates the phenomena involved in distribution process. Some reference results are presented. Inatantanerous backflow into the cylinder and pressure distribution of the oil film are shown. Meanwhile, the reasons for the cavity inception during the flow distribution process are analyzed.Based on the contours of volume fraction, the region and the degree of cavitation occurred in the internal flow are predicted. A new method of flow coefficient theoretical analysis is applied: in accordance with the simulation results, the flow coefficient and the rotation angle of flow equations are obtained. The forces and moments exerted on the cylinder block are also achieveved. Behaviors of an axial piston pump in a specific range of operating condition are analyzed in detail. Some researches on the impact of relief groove on the performance of axial piston pump are conducted as well.The fourth chapter focuses on the preliminary design of a test rig of axial piston pump to test the flow ripples on the pump outlet. This data is used to validate the simulation results, and then validate the legitimacy of the mathematical model, the specification of boundary conditions and initial conditions.The fifth chapter is the summary of the paper's study work and the prospect of the next step's work.