Dynamic behavior of gear pumps: effect of variations in operational and design parameters

Mucchi, Emiliano; Dalpiaz, Giorgio; Rivola, Alessandro

doi:10.1007/s11012-010-9376-y

Cited by 29 publications

(22 citation statements)

References 7 publications

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“…The last contribution to the reduction of volumetric efficiency is due to the engaging process. In the engaging region, when two teeth pairs come into contact, a trapped volume could arise and, in the case of the wrong design, it can experience a progressive volume reduction, leading to a sudden change in pressure [11]. To avoid this, the trapped volume is always connected with the high-or low-pressure chamber.…”

Section: Gear Pump Virtual Model and Main Featuresmentioning

confidence: 99%

“…The damping effects provided by the pipeline are usually not able to eliminate the vibrations [9,10], which are also responsible for disturbances and, sometimes, the damage of measurement devices. Pulsations are due to the pressure ripples provided by the pump, which are driven by the engagement process and the position of the relief grooves [11].…”

Section: Introductionmentioning

confidence: 99%

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Pressure Pulsation and Cavitation Phenomena in a Micro-ORC System

et al. 2019

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Micro-ORC systems are usually equipped with positive displacement machines such as expanders and pumps. The pumping system has to guarantee the mass flow rate and allows a pressure rise from the condensation to the evaporation pressure values. In addition, the pumping system supplies the organic fluid, characterized by pressure and temperature very close to the saturation. In this work, a CFD approach is developed to analyze from a novel point of view the behavior of the pumping system of a regenerative lab-scale micro-ORC system. In fact, starting from the liquid receiver, the entire flow path, up to the inlet section of the evaporator, has been numerically simulated (including the Coriolis flow meter installed between the receiver and the gear pump). A fluid dynamic analysis has been carried out by means of a transient simulation with a mesh morphing strategy in order to analyze the transient phenomena and the effects of pump operation. The analysis has shown how the accuracy of the mass flow rate measurement could be affected by the pump operation being installed in the same circuit branch. In addition, the results have shown how the cavitation phenomenon affects the pump and the ORC system operation compared to control system actions.

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Section: Gear Pump Virtual Model and Main Featuresmentioning

confidence: 99%

Section: Introductionmentioning

confidence: 99%

Pressure Pulsation and Cavitation Phenomena in a Micro-ORC System

et al. 2019

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“…Wang et al [19] applied the control volume approach, focusing on the analysis and optimization of the design of the machine to improve performance. Mucchi et al [20,21] have also studied external gear pumps by means of a lumped parameter approach coupled with a finite element model, with special focus on vibration and noise emissions analyses. All these contributions have been important to generate knowledge about the physical phenomena influencing the performance of these kinds of positive displacement machines, and at the same time, to improve and propose new designs.…”

Section: Introductionmentioning

confidence: 99%

Evaluation of the Hydro—Mechanical Efficiency of External Gear Pumps

2019

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This paper proposes and describes a model for evaluating the hydro-mechanical efficiency of external gear machines. The model is built considering and evaluating the main friction losses in the machines, including the viscous friction losses at the tooth tip gap, at the bearing blocks-gears gaps, at the journal bearings, and the meshing loss. To calculate the shear stress at each gap interface, the geometry of the gap has to be known. For this reason, the actual position of the gears inside the pump casing and consequent radial pressure distribution are numerically calculated to evaluate the gap height at the tooth tips. Moreover, the variation of the tilt and reference height of the lateral gaps between the gears and the pump bushings are considered. The shear stresses within the lateral gaps are estimated, for different lateral heights and tilt values. At the journal bearings gaps, the half Sommerfeld solution has been applied. The meshing loss has been calculated according to the suggestion of the International Standards. The hydro-mechanical efficiency results are then discussed with reference to commercial pumps experimentally characterized by the authors in a previous work. The average percentage deviation from experimental data was around 2%, without considering the most critical operating conditions (high delivery pressure, low rotational speed). The limits of this approach are also explained. Finally, the role of each source of loss is discussed, considering different operating conditions and two values of fluid viscosity. Lateral gap losses and meshing loss are much more relevant in determining the hydro-mechanical efficiency variation in the pump’s operating range, especially at a low delivery pressure. Moreover, while lateral gap losses increase with the rotational speed, the meshing loss shows the opposite behavior. The tooth tip gap losses are never as relevant, but they increase at high pressure. The journal bearings losses become comparable with the lateral and meshing ones at high delivery pressure values. Considering the pumps analyzed and the operating range of delivery pressure values and rotational speed values, the meshing loss made the mechanical efficiency vary in a percentage range of ±7%, with lateral losses in the range of about the ±15%, when also considering the extreme operating points (low speed, high pressure; high speed, low pressure). The weight of the lateral losses slightly reduced when we analyzed the higher temperature results, while the meshing losses slightly increased.

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“…Manring and Kasaragadda [1] described the pressure and spectral characteristics of the pulse of flow related to the number of teeth of an external gear pump where the rotation axis distance is an important parameter. Mucchi et al [9,10] go further in describing similar results, and the effects of the gear vibrations and forces applied to the casing have been analyzed.…”

Section: Introductionmentioning

confidence: 88%

Experimental study on the impulsion port of a trochoidal wheeled pump

Raush

Gamez-Montero

Castilla

et al. 2017

Flow Measurement and Instrumentation

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© 2017. This version is made available under the CC-BY-NC-ND 4.0 license http://creativecommons.org/licenses/by-nc-nd/4.0/All positive displacement pumps produce a pulsating flow. The present paper reports the experimental measurement of steady flow pulsations in the outlet of the internal wheeled pump. In the measured flow, the manufacturing tolerance are responsible of part of the spectra of the whole pulsation. Time-Resolved Particle Image Velocimetry technique has been used for this purpose. The flow pulsation measurement from a direct visualization of the velocity profile was carried out. The flow rate signal is derived from ad-hoc integration algorithm of the radial velocity profile, where the area discretization is a constant parameter that is relevant to minimize PIV errors by velocity gradients regions near the wall. Spectrographic analysis on the experimental data reveled low frequency components related with manufacturing tolerances. Measurements of this non-invasive procedure are compared with detailed CFD numerical results obtained from an improved gerotor model where manufacturing tolerances have been included. To be compared, cross-power spectral density analysis has been applied. The results reported in the paper show a method to provide a fast non-invasive flow pulsation measurement not only for pumps but also could be extended to compare aging effects of other kind of fluid power devices.Peer ReviewedPostprint (author's final draft

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Dynamic behavior of gear pumps: effect of variations in operational and design parameters

Cited by 29 publications

References 7 publications

Pressure Pulsation and Cavitation Phenomena in a Micro-ORC System

Pressure Pulsation and Cavitation Phenomena in a Micro-ORC System

Evaluation of the Hydro—Mechanical Efficiency of External Gear Pumps

Experimental study on the impulsion port of a trochoidal wheeled pump

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