Three-Dimensional Numerical Simulation of an External Gear Pump With Decompression Slot and Meshing Contact Point

Abstract

Recently several works have been published on numerical simulation of an external gear pump (EGP). Such kinds of pumps are simple and relatively inexpensive, and are frequently used in fluid power applications, such as fluid power in aeronautical, mechanical, and civil engineering. Nevertheless, considerable effort is being undertaken to improve efficiency and reduce noise and vibration produced by the flow and pressure pulsations. Numerical simulation of an EGP is not straightforward principally for two main reasons. First, the gearing mechanism between gears makes it difficult to handle a dynamic mesh without a considerable deterioration of mesh quality. Second, the dynamic metal–metal contact simulation is important when high pressure outflow has to be reproduced. The numerical studies published so far are based on a two-dimensional (2D) approximation. The aim of the present work is to contribute to the understanding of the fluid flow inside an EGP by means of a complete three-dimensional (3D) parallel simulation on a cluster. The 3D flow is simulated in a linux cluster with a solver developed with the openfoam Toolbox. The hexahedral mesh quality is maintained by periodically replacing the mesh and interpolating the physical magnitudes fields. The meshing contact point is simulated with the viscous wall approach, using a viscosity model based on wall proximity. The results for the flow rate ripples show a similar behavior to that obtained with 2D simulations. However, the flow presents important differences inside the suction and the discharge chambers, principally in the regions of the pipes' connection. Moreover, the decompression slot below the gearing zone, which can not be simulated with a 2D approximation, enables a more realistic simulation of a contact ratio greater than 1. The results are compared with experimental measurements recently published.

Study of a High-Pressure External Gear Pump with a Computational Fluid Dynamic Modeling Approach

“…Those gaps become crucial in the study of these pumps that, as said, work at a very low speed (500 rpm). Castilla et al [12], have also built up a complete 3D model of an external gear pump developed with an OPENFOAM Toolbox. No simulation models have been found for the study of cavitation.…”

Research on Flow Characteristics of Straight Line Conjugate Internal Meshing Gear Pump

“…From the continuous contact transmission's conditions of the tooth profile, it can be known that transmission ratio 12 1 i > in the internal meshing gear pair, that is, the value of expression 1 i − is a positive number less than 1. Therefore, when f is 0, that is, when the node coincides with the meshing point, the instantaneous flow rate reaches the maximum; when f is maximum, it is at the minimum.…”

“…According to the basic theorem of the tooth profile meshing (i.e., the common normal of two conjugate tooth profiles at the contact point passes through the instantaneous velocity center), in other words, the line between the meshing point and the node is perpendicular to the external gear's profile curve. Based on this and according to the geometric relationship in Figure 4, the equation sets about 1 ρ and 2 ρ can be obtained:…”

“…With the continuous development of hydraulic technology, digital and intelligent hydraulics have become hotspots in the industry. The advancement of the body part and the improvement of the hydraulic pump's overall performance (e.g., high pressure, low noise, low pulsation, and large and variable displacements) are also an objective of intelligent hydraulics [1][2][3][4][5]. The average flow rate, flow pulsation and internal flow field distribution are collectively referred to as the flow characteristics of gear pumps, which are the key factors affecting the large displacement, low pulsation, and low noise.…”

Experimental study on the impulsion port of a trochoidal wheeled pump

“…The contraction of the mesh deformation and local re-meshing was carried out following an arbitrary Lagrangian-Eulerian approach. More recently, Castilla et al [6] contribute to the understanding of the fluid-dynamics flow inside an external gear pump using a complete three-dimensional (3D) parallel simulation.…”