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Numerical simulation of Gerotor pumps considering rotor micro-motions

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Abstract

Gerotor units are widely used in low-pressure (up to 30 bar) fluid power applications, injection as well as lubrication systems, due to their compact package and low cost. Their performance in terms of volumetric efficiency, flow pulsations, internal pressure peaks or localized cavitation depends on many parameters, such as the rotors’ profiles and the manufacturing tolerances. This paper proposes a multi-domain simulation approach for the numerical analysis of the performance of Gerotor units. Characterized by simulation swiftness, the model can be used for virtual prototyping of units considering the actual geometry of the rotors, their geometrical tolerances and the properties of the working fluid. The approach is based on the coupling of different models: a numerical geometric model evaluates the instantaneous volumes and flow areas inside the unit; a lumped parameter fluid dynamic model describes the displacing process of the tooth space volumes; finally, a mechanical model evaluates the internal micro-motions of the rotors axes according to their tolerances. In this way, the model determines the actual loading of the rotors, considering also the actual location of the points of contact. After presenting the approach, the paper describes the potentials of the proposed method with reference to a particular Gerotor pump design. Specific experiments were performed within this research to permit a detailed model validation, and comparisons in terms of significant steady-state as well as transient pressure and flow features are presented. The approach used in the current paper can be considered valuable when studying the impact of real-life technological clearances on the fluid-dynamic performance of the pump.

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Abbreviations

A :

Area

b :

Width

D :

Diameter

e :

Eccentricity

F, f :

Force

h :

Height

l :

Length

\(\dot{m}\) :

Mass flow rate

p :

Pressure

P :

Perimeter

Q :

Volumetric flow rate

r :

Radius

t :

Time

T :

Torque

V :

Volume

\(x,y,X,Y\) :

Distances of line of action of force (components) from the rotor center

w :

Rotors’ width

\(\alpha\) :

Coefficient of discharge

\(\phi\) :

Angle defining the direction of the contact force with respect to the global reference system

ρ :

Density

\(\mu\) :

Fluid viscosity

\(\nu\) :

Kinematic viscosity

θ :

Angle

ω :

Angular velocity

\(\varOmega\) :

Area of action of the pressure load

c :

Contact

DC :

Displacement chamber

H :

Hydraulic

i :

Index

in :

Entering

inn :

Inner

out :

Outer/leaving

P :

Pressure of the suction/delivery environment

ref :

Reference conditions

t :

Tip of the profile

\(x,y,z\) :

Cartesian components

HP:

High pressure

LP:

Low pressure

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Acknowledgments

The authors would like to thank Thomas Magnete GmbH (Etienne Dautry and Benjamin Gisberg) for their valuable support and for providing experimental data for the present study. The authors would like to thank Siemens for the use of Imagine.Lab AMESim.

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Authors and Affiliations

  1. MAHA Fluid Power Research Center, Purdue University, West Lafayette, IN, USA

    M. Pellegri & A. Vacca

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  1. M. Pellegri
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  2. A. Vacca
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Correspondence to M. Pellegri.

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Pellegri, M., Vacca, A. Numerical simulation of Gerotor pumps considering rotor micro-motions. Meccanica 52, 1851–1870 (2017). https://doi.org/10.1007/s11012-016-0536-6

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