A strongly coupled simulation model for external gear machines considering fluid-structure induced cavitation and mixed lubrication

Ransegnola, Thomas; Zappaterra, Federico; Vacca, Andrea

doi:10.1016/j.apm.2021.11.035

Cited by 18 publications

(12 citation statements)

References 35 publications

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“…The current model is developed in C++ environment with an in-house manner as a complimentary part to the Multics-HYGESim developed at the author's lab for other gear machines [24]. The current model is fairly fast, as it takes about 35 min on a personal PC (i7-3770, 16 GB RAM) to finish a simulation of 720°shaft angle, and less than 5 min to complete the stand-alone lumped simulation for the same angle period.…”

Section: Discussionmentioning

confidence: 99%

“…( 10) transits the Reynolds equation of pressure [25] from a non-linear form into a linear one for density, allowing to achieve its numerical solution with an explicit strategy. After the density distribution is solved, pressure distribution will be determined by assuming a static dependence for the fluid properties (such as density and pressure) [24]. In this work, central difference and upwind format are applied to the spatial derivatives terms respectively on the left and right side of Eq.…”

Section: Computational Fluid Dynamics Modelling Of the Radial Films 2...mentioning

confidence: 99%

“…The radial films specified in Fig. 1 are solved assuming quasi‐steady laminar flow using the universal Reynolds equation 24, i.e.,

true \nabla (\frac{K h^{3}}{12 μ} \nabla ρ) = \nabla (ρ h \underset{true¯}{ν}) + ρ \frac{\partial h}{\partial t}

…”

Section: Modelling Approachmentioning

confidence: 99%

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Modeling of Crescent‐Type Internal Gear Pumps Considering Gear Radial Micromotion

Pan

Vacca

2022

Chem Eng & Technol

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This paper presents a numerical modeling approach for investigating crescent‐type internal gear pumps (CIGPs) considering radial micromotions of both gears. The modeling approach couples a lumped parameter pressure solver on the bulk fluid domain, with a transient computational fluid dynamics film simulator based on transient gap geometries solved from the gear loading forces. Simulation results on a commercial unit shows that for a wide range of operating conditions, the model gives volumetric efficiency predictions with errors less than 2 % comparing to measurements. To highlight the importance of considering radial micromotions, the paper also provides the results achieved assuming nominal position for both gears.

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Section: Discussionmentioning

confidence: 99%

Section: Computational Fluid Dynamics Modelling Of the Radial Films 2...mentioning

confidence: 99%

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Modeling of Crescent‐Type Internal Gear Pumps Considering Gear Radial Micromotion

Pan

Vacca

2022

Chem Eng & Technol

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“…Thiagarajan and Vacca [12] extended this work to include the mixed lubrication regime modelling and effect of surface roughness on the lateral lubricating film power losses. A recent work from the authors' team [13] introduced the multi-domain simulation tool Multics-HYGESim, which allows the simultaneous/coupled analysis of different domains of an EGP. The tool, which will be further described in Section 2, has a modular structure, and can accommodate new modules such as the housing deformation and the gear meshing ones presented respectively in [14,15].…”

Section: Introductionmentioning

confidence: 99%

A Study on the Effects of Body Deformation on the Performance of External Gear Machines

Pawar,

Vacca,

Rigosi

2024

14th International Fluid Power Conference

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The energy efficiency of external gear pumps (EGPs), similar to all positive displacement machines used for high-pressure applications, is significantly influenced by the power losses occurring in the lubricating interfaces that seal the internal displacement chambers. Therefore, it is crucial to account for these interfaces accurately, when developing predictive simulation tools. However, the literature has suggested various modelling approaches for EGPs, with different assumptions regarding the analysis of these interfaces. This makes it challenging for a designer or a researcher to determine what are the essential physical domains needed for properly modelling the lubricating interfaces and assess the EGP performance.This paper addresses the above research question by leveraging a comprehensive simulation tool (Multics-HYGESim) developed by the authors' research team to compare the effect of different modelling assumptions. HYGESim includes tribological considerations pertaining to the meshing of the gears, the lubricating films at the tooth tip interfaces, at the journal bearings, and at the lateral interfaces. It also considers realistic fluid properties, including the effects of cavitation and aeration, mixed lubrication effects, as well as material deformation effects for the gears, lateral bushings and the EGP housing. Deformation of the internal parts of an EGP is related to the internal balancing features and it is strongly coupled with the instantaneous pressurization of the pumping volumes. For this reason, a realistic quantification of these effects is difficult in simulation.Using a commercial EGP design as a reference, with known experimental volumetric and hydromechanical efficiency, this paper demonstrates how predictions can vary based on different simulation assumptions regarding body and lubricating film behaviours. Results are discussed starting from a basic rigid-body assumption that considers only body motion and analytical formulations of lubricating interfaces, to simulation model cases of progressively increasing in complexity to account for deformations of gears, bushings and housing. The results show that consideration of deformation effects allow more accurate prediction of power losses and efficiencies of the pump while simulations carried out without deformation considerations approximate the leakages and the power losses at the lateral lubricating interface though can predict the fluid dynamic performance. These findings will offer valuable insights to EGP designers, enabling them to understand the strengths and limitations of different modeling assumptions on the prediction of EGP behavior, especially regarding the effects of body deformation.

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“…The design integrates a hydraulic machine (HM) coupled with a permanent magnet type electric machine (EM) without any external shaft. The unit, which is described in [17,18], and [19], uses an external gear type hydraulic machine with a maximum power of 15 kW. This unit is air-cooled using fans mounted on the rotor of the electric machine.…”

Section: Introductionmentioning

confidence: 99%

Experimental Verification of An Electro-Hydraulic Actuation System Driven by An Integrated Electro-Hydraulic Unit

Qu¹,

Zappaterra²,

Vacca³

et al. 2023

TJFP

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This paper proposes an electro-hydraulic actuator (EHA) system, and a novel-designed electro-hydraulic unit (EHU) consisting of a fixed-displacement hydraulic gear machine and a variable-speed electric machine. The novel EHU design integrates an electric machine and a hydraulic machine in a single housing, targeting optimal compactness, power density, and component reduction. The EHA system features an open circuit design, where hydraulic hoses connect the EHU with a tank, a valve manifold, and the hydraulic cylinder. In this way, the proposed EHA technology can be used to implement distributed hydraulic actuation in a vehicle without requiring changes to the hydraulic actuators or at the overall layout of the hydraulic components with respect to the original vehicle design. A dedicated test rig is developed to verify the performance of the proposed EHA system. The efficiency of the EHA is measured in a steady state and under a realistic duty cycle of a commercial compact loader. The efficiency of the EHA system based on the measurements on the test rig can reach 54% with up to 20 kN load and 6 kW power level. Furthermore, the EHU is implemented on the reference machine to drive the boom function. Preliminary results on the performance of the EHU show an efficiency of up to 68% under different loading conditions.

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A strongly coupled simulation model for external gear machines considering fluid-structure induced cavitation and mixed lubrication

Cited by 18 publications

References 35 publications

Modeling of Crescent‐Type Internal Gear Pumps Considering Gear Radial Micromotion

Modeling of Crescent‐Type Internal Gear Pumps Considering Gear Radial Micromotion

A Study on the Effects of Body Deformation on the Performance of External Gear Machines

Experimental Verification of An Electro-Hydraulic Actuation System Driven by An Integrated Electro-Hydraulic Unit

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