Finite Element Modeling of a Viscous Fluid Flowing through an External Gear Pump

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An external gear pump is a relatively simple and inexpensive pump, that is used in a variety of production systems. Numerous works have studied the external gear pump using numerical simulations; however, typically low-viscosity fluids and turbulent flow conditions are considered. Previous work of the authors focused on predicting the output fluctuation and the volumetric efficiency of an external gear pump processing high-viscosity fluids using a 2D representation. For certain conditions, backflow through all clearances could occur, resulting in a drop in volumetric efficiency. This calls for a full 3D model. Furthermore, high residence time zones are observed in the inflow channel of the pump. The 3D shape of these zones is still unknown. The aim of this work is to investigate the effect of the axial clearances on the performance of the external gear pump. A 3D mesh is generated by extruding the 2D mesh in the third direction, resulting in prism elements. This reduces the required number of elements and therewith makes the simulations computationally feasible. Introducing the axial clearances results in a lower efficiency compared to the 2D simulations. With particle tracking, the high residence time zones in the inflow channel are visualized in the 3D simulations.

Section: Methodsmentioning

confidence: 99%

Section: Introductionmentioning

confidence: 95%

Section: Problem Definition and Governing Equationsmentioning

confidence: 99%

Section: Mesh Convergencementioning

confidence: 99%

Section: Introductionmentioning

confidence: 99%

See 3 more Smart Citations

Three‐Dimensional Finite Element Modeling of a Viscous Fluid Flowing through an External Gear Pump

Bie

Luijten

Hulsen

et al. 2021

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Numerical Modeling of the Blend Morphology Evolution in Twin‐Screw Extruders

Wong

Bie

Hulsen

et al. 2022

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The blend morphology model developed by Wong et al., based on Peters et al., is used to investigate the development of the disperse polymer blend morphology in twin-screw extruder flow. First, the model is written in a point-wise form suitable for using in conjunction with particle tracking. Particle tracking methods are used to generate trajectories along the flow field. Macroscopic droplet populations are placed along these trajectories and the velocity gradient tensor is extracted and applied on the point-wise blend morphology model. Very large morphology differences arise between trajectories that pass through the middle gap and those that do not. In the global distribution of (macroscopically averaged, monodisperse) droplet sizes, two distinct peaks appear due to these different trajectories. Given enough number of screw rotations, a droplet population can reach almost every position in the twin-screw extruder and travel along both types of particle trajectories. The effect of varying the gap size is that the largest droplets are unaffected, but the smallest droplets are smaller for a smaller gap size due to the higher maximum shear rate. The effect of varying the viscosity ratio on the global droplet size distribution is found to be nonlinear and is strongly determined by the Grace curve. The effect on polydisperse droplet populations is found to be that trajectories that do not pass through the gap evolve toward a single peak, whereas trajectories that do pass through the gap lead to a split into two peaks that ultimately rejoin as one peak. It is concluded that the initial position of a population in the twin-screw extruder has a very large effect on the developing transient blend morphology, though future work should be done on the importance of the initial position on the steady-state blend morphology after a very large number of screw rotations.

Numerical Modeling of the Blend Morphology Evolution in Twin‐Screw Extruders

Wong¹,

Bie²,

Hulsen³

et al. 2022

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