Gear pumps represent the majority of the fixed displacement machines used for flow generation in fluid power systems. In this context, the paper presents a review of the different methodologies used in the last years for the simulation of the flow rates generated by gerotor, external gear and crescent pumps. As far as the lumped parameter models are concerned, different ways of selecting the control volumes into which the pump is split are analyzed and the main governing equations are presented. The principles and the applications of distributed models from 1D to 3D are reported. A specific section is dedicated to the methods for the evaluation of the necessary geometric quantities: analytic, numerical and Computer-Aided Design (CAD)-based. The more recent studies taking into account the influence on leakages of the interactions between the fluid and the mechanical parts are explained. Finally the models for the simulation of the fluid aeration are described. The review brings to evidence the increasing effort for improving the simulation models used for the design and the optimization of the gear machines.

Models for Flow Rate Simulation in Gear Pumps: A Review

Numerical Analysis of External Gear Pumps Including Cavitation

A review of recent studies on piezoelectric pumps and their applications

Analysis of a scroll machine for micro ORC applications by means of a RE/CFD methodology

A study on the internal fluid dynamic of a high-pressure external gear pump is described in this paper. The pump has been analyzed with both numerical and experimental techniques. Starting from a geometry of the pump, a three-dimensional computational fluid dynamics (CFD) model has been built up using the commercial code PumpLinx®. All leakages have been taken into account in order to estimate the volumetric efficiency of the pump. Then the pump has been tested on a test bench of Casappa S.p.A. Model results like the volumetric efficiency, absorbed torque, and outlet pressure ripple have been compared with the experimental data. The model has demonstrated the ability to predict with good accuracy the performance of the real pump. The CFD model has been also used to evaluate the effect on the pump performance of clearances in the meshing area. With the validated model the pressure inside the chambers of both driving and driven gears have been studied underlining cavitation in meshing fluid volume of the pump. For this reason, the model has been implemented in order to predict the cavitation phenomena. The analysis has allowed the detection of cavitating areas, especially at high rotation speeds and delivery pressure. Isosurfaces of the fluid volume have been colored as a function of the total gas fraction to underline where the cavitation occurs.

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

Numerical simulation of turbulent flow in the suction chamber of a gearpump using deforming mesh and mesh replacement

Experimental analysis of the flow dynamics in the suction chamber of an external gear pump

Small-scale characteristics and turbulent statistics of the flow in an external gear pump by time-resolved PIV

Appropriate flow seeding is particularly critical with in the particle image velocimetry (PIV) technique that indirectly measures the displacement from the particle velocity instead of fluid velocity. Particles that follow the flow accordingly and scatter enough light must be used in order to obtain accurate velocity field of the flow. Therefore, particles should be as small as possible in order to ensure good tracking of the fluid motion and they should not be too small, since they will not scatter enough light. The microparticles can be obtained from approximately 20 nm to around 50 ?m in a controlled manner with ability increasing their light scattering behavior by fluorescein imbedding so that they gain the light scattering property. Alginate microparticles as flow seeding fulfill all the requirements that are recommended for the velocity measurements in PIV. These spherical microparticles offer the advantage of being environmentally friendly, excellent seeding properties and very simple production ability. They can be obtained as small as possible while increasing its scattering behavior by adding fluorescein into them. Additionally, they can be perfectly used as flow seeding in gas and several liquid flows with matching densities.

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N. Ertürk

Papers

Numerical simulation of turbulent flow in the suction chamber of a gearpump using deforming mesh and mesh replacement

Experimental analysis of the flow dynamics in the suction chamber of an external gear pump

Small-scale characteristics and turbulent statistics of the flow in an external gear pump by time-resolved PIV

Alginate flow seeding microparticles for use in Particle Image Velocimetry (PIV)