Abstract

Fluid starvation and congestion at the meshing area of external gear pumps (EGP) happen inevitably as an intrinsic nature of these pumps. As a result, cavitation and excessive pressure pulsation are the two significant issues suffering the pump performance at almost any pump speed. Increasing speed or differential pressure exacerbates the situation, resulting in excessive noise, vibration, and damage to the pump or the hydraulic circuit, plus a significant reduction of pump efficiency. External gear pumps have tiny decompression grooves on the bearing blocks to alleviate these issues. However, these grooves cannot handle sufficient flow to prevent pressure drop at the intake side and pressure rise at the discharge side of the meshing area. This study presents analysis of an innovative Core-Feed inlets/outlets which effectively reduce cavitation and excessive pressure pulsation, even at extremely high speeds, by connecting the closed volumes of fluid at the gears meshing area to the main inlet/outlet through the center of gears. A computational fluid dynamics (CFD) analysis was performed to study the dynamic behavior of the pump. A fully functional prototype with secondary inlets and transparent components was built to validate the flow rate calculation against the experimental data and visualize the cavitation phenomena. The numerical results were in an excellent agreement with experimental data. The results show that the new pump can operate at much higher speeds with higher efficiency than a typical gear pump.

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