Pressure effects on the performance of external gear pumps under cavitation

Abstract

The numerical analysis of an external gear pump with cavitation effects has been validated with experimental data obtained by applying Time-Resolved Particle Image Velocimetry. The effect of inlet and outlet pressure on volumetric efficiency has been studied numerically. First, the Particle Image Velocimetry method was used to analyze the two-dimensional velocity field in the middle plane of the suction chamber of the gear pump. The main improvement, with respect to previous similar analysis is the use of alginate micro particles as tracers. It is seen that the two-dimensional model is able to characterize the flow field of the real pump in the region of the inlet chamber in which cavitation is expected. In a previous study, it was seen that a cavitation cloud acted as a virtual contact point at low pressure, being responsible for an increase on the volumetric efficiency. The first set of simulations represents the pump working with high outlet pressure. Now, the cavitation cloud is not present and cavitation no longer helps to improve the efficiency of the pump. The second set of simulations represents the pump with an inlet loss factor, which implies a mean inlet pressure below atmospheric conditions. This allows cavitation clouds to propagate upstream. Despite the larger cavitation clouds, volumetric efficiency only drops at high operating velocities, when some clouds become trapped between gears and casing and are transported to the pressure side.Peer ReviewedPostprint (published version

Evaluation of the Hydro—Mechanical Efficiency of External Gear Pumps

“…Vacca et al [9][10][11][12][13] developed a complex numerical model able to simulate the radial balance of the external gear machine together with a detailed analysis of the lubricating gaps, considering the elastic deformation of the surfaces due to the pressure and temperature distribution inside the gaps. Moreover, del Campo et al [14,15] applied extensive CFD analysis and experimental measurements, focusing in particular on the study of cavitation and of the meshing process of external gear pumps. Cavitation in external gear pumps is a topic also improved by Edge et al in [16], Borghi et al in [17], and Frosina et al in [18], with different approaches, using in-house and commercial CFD code.…”

Research on Identification Method of Wear Degradation of External Gear Pump Based on Flow Field Analysis

“…Frosina et al [7] studied the pressure in the cavity of the driving gear and the driven gear through the combination of virtual simulation for gear pump and test. Campo et al [8] verified the numerical analysis of the gear pump with the experimental data, and identified the influence of the inlet and outlet pressure on the volumetric efficiency accessing an image velocity measurement method. Yoon et al [9] proposed a simulation method of pump performance characteristic parameters, and the working process of the gear pump under high-speed extreme conditions is simulated by the immersed solid method.…”

Incipient cavitation detection in external gear pumps by means of vibro-acoustic measurements

“…The model described in [17] is supported by experimental data referring to the pressure ripple around gears, but no effective data regarding the cavitation detection are provided. Effects produced by cavitation in external gear pumps have also been evaluated by using 2D Computational Fluid Dynamic (CFD) approaches as the one proposed by del Campo et al in [19,20], where the performed simulations predicted the effects of cavitation to be restricted on the inlet flow rate/pressure ripple, exclusively. Simulated results are supported by qualitative comparison with inlet chamber streamlines detected by using Time-Resolved Particle Image Velocimetry; however, no effective detection of cavitation is performed.…”