Numerical and experimental analysis of an external gear pump efficiency – literature review and lumped parameter approach capability

The volumetric and hydro-mechanical efficiencies describe the performance of external gear machines (EGMs), pumps and motors. In the last decades, several lumped parameter models have been designed to simulate EGMs and predict their efficiencies. The early works have focused on the prediction of the volumetric efficiency, and only in the last years have several models capable of predicting the hydro-mechanical efficiency been developed. The purpose of this work is double. 1) Provide an overview of the approaches developed and used by other authors to compute the hydro-mechanical efficiency with a lumped parameters model. 2) Show the capability of a lumped parameters model to compute the main sources of internal forces and resistive torques in an external gear pump (EGP). The torque losses considered are the viscous contributions on the tooth tip, on the gear sides, and within the journal-bearings, and the torque loss due to the gears mesh. In the present work a 20 cm ³ /rev EGP with a maximum operating pressure of 240 bar is analysed. Lastly, the results of the numerical model are compared with the ones returned by the experimental characterisation of the pump and by a 3D CFD model developed in the Simerics MP+ environment.