Numerical Study of the Hydrodynamics of an External Gear Pump

The paper presents a three-dimensional numerical model that describes the operation of a gear pump, taking into account turbulence and cavitation. The model proposed is implemented in the ANSYS CFX software package. The algorithm for the simulation of moving boundaries (rotation of gears) is based on the immersed solid method. The formation of cavitation in the flow of a viscous incompressible fluid is simulated using a homogeneous two-phase model. The adequacy of the numerical analog developed was verified: on its basis, the analysis of the stability and convergence of the solution was carried out. A series of numerical experiments corresponding to the experimental design stage of creating a fuel system for a promising gas turbine engine were conducted. The technical characteristics of the pump-flow rate, cavitation localization zones, and the degree of cavitation-were obtained. The results of simulation for various operation modes of the unit under study, with different rotational speeds of the gears, are presented. The calculated flow rates for the single-phase (without cavitation) and two-phase flow model are compared with the data of a theoretical calculation using an engineering technique. The supposed cavitation formation zones and the cavitation level are shown and substantiated. The cavitation flow of a real liquid (aviation kerosene) is considered: depending on the rotational speed of the gear, the localization and relative volume of regions subject to cavitation, its concentration, and its possible effect on the consumption rate of the pump and its wear resistance are studied. The simulation results are presented in the form of functional dependences and patterns of the location of cavitation zones. The numerical model of a gear pump makes it possible to carry out numerical experiments instead of expensive full-scale physical experiments and give recommendations for preventive improvement of the design even before the production of prototype products.