scholarly journals Evaluation of Tooth Space Pressure and Incomplete Filling in External Gear Pumps by Means of Three-Dimensional CFD Simulations

Energies ◽  
2021 ◽  
Vol 14 (2) ◽  
pp. 342
Author(s):  
Alessandro Corvaglia ◽  
Massimo Rundo ◽  
Paolo Casoli ◽  
Antonio Lettini
Keyword(s):  
Three Dimensional ◽  
Operating Conditions ◽  
Dynamics Simulation ◽  
Inlet Pressure ◽  
Gear Pump ◽  
External Gear Pumps ◽  
Internal Fluid ◽  
Incomplete Filling ◽  
Gear Pumps ◽  
High Dynamics

The paper presents the computational fluid dynamics simulation of an external gear pump for fluid power applications. The aim of the study is to test the capability of the model to evaluate the pressure in a tooth space for the entire shaft revolution and the minimum inlet pressure for the complete filling. The model takes into account the internal fluid leakages and two different configurations of the thrust plates have been considered. The simulations in different operating conditions have been validated with proper high dynamics transducers measuring the internal pressure in a tooth space for the entire shaft revolution. Steady-state simulations have been also performed in order to detect the fall of the flow rate due to the incomplete filling of the tooth spaces when the inlet pressure is reduced. It has been demonstrated that, despite the need of a compromise for overcoming the limitation of considering fixed positions of the gears’ axes and of the thrust plates, significant results can be obtained, making the CFD approach very suitable for such analyses.

A Numerical Procedure to Design the Optimal Axial Balance of Pressure Compensated Gear Machines

2014 ◽  
Author(s):  
Divya Thiagarajan ◽  
Andrea Vacca
Keyword(s):  
Numerical Procedure ◽  
Operating Conditions ◽  
Force Balance ◽  
Gear Pump ◽  
Power Losses ◽  
Outlet Port ◽  
External Gear Pumps ◽  
Gear Pumps ◽  
Force Components ◽  
External Gear Pump

This paper presents an innovative numerical procedure to determine the optimal balancing area of lateral bushes in external gear pumps or motors. In pressure compensated designs of external gear machines, the lateral bushes perform the important functions of sealing the tooth space volumes while they transfer fluid from the inlet to the outlet port. In normal operating conditions, a lubricating gap exists between the lateral bush and the gear permitting to minimize losses due to shear stress and leakage. These conditions are found by determining proper balancing areas at the side of the bushes not facing the gears, in which the pressure of the high pressure port is properly established. This problem is also known as “axial balance” of external gear machines. To determine the optimal axial balance which minimizes the power losses associated with the lubricating gap in all operating conditions, all the static and hydrodynamic forces acting on the lateral bushes have to be considered. This delicate aspect of external gear units design is usually addressed through empirical procedures; while in this paper an automatic numerical procedure is presented. The proposed method is based on the solution of the force balance of the lateral bushes, taking into account all force components, including the hydrodynamic terms due to the relative inclination between bushes and gears and material deformation. After detailing the procedure, the paper describes its potentials by showing the advantages arising from the optimization of the axial balance of a particular external gear pump for fluid power applications.

Evaluation of Non-Cavitating Steady State Performance of an Aero-Engine Gear Pump by Numerical Methods

2017 ◽  
Author(s):  
Shivakumar Ulaganathan ◽  
Ch. Kanna Babu ◽  
Girish Kalyanrao Degaonkar
Keyword(s):  
Numerical Analysis ◽  
Three Dimensional ◽  
Turbulence Models ◽  
Internal Flow ◽  
Operating Conditions ◽  
Gear Pump ◽  
Design Features ◽  
Flow Features ◽  
Gear Pumps ◽  
Aero Engines

External gear pumps are typically used in aero-engines for the fuel and lubrication system due to its simplicity in construction. The design of the gear pump has been considerably improved over several years by including design features to improve its overall performance and reliability. In this paper, three-dimensional numerical analysis of an external gear was carried out by including design features such as scallops at the inlet and outlet, radial and axial clearances, journal bearing clearances and the axial tilt of the supporting bushes. The Immersed Solid Method (ISM) is used to analyze the gear pump at different operating conditions. The applicability of different turbulence models to the Immersed solid method is discussed. The internal flow features are discussed and compared with the results available in the literature. The Pump characteristics curve developed from the numerical analysis using the Immersed solid method (ISM) is compared with the experimental test results.

scholarly journals Modeling the Efficiency of External Gear Pumps Based on Similarity Considerations

2018 ◽  
Author(s):  
C. Schänzle ◽  
N. Störmer ◽  
P. F. Pelz
Keyword(s):  
Power Consumption ◽  
Flow Rate ◽  
Volume Flow Rate ◽  
Measurement Data ◽  
Volume Flow ◽  
Operating Conditions ◽  
Gear Pump ◽  
Industrial Sectors ◽  
External Gear Pumps ◽  
Gear Pumps

Gear pumps are used in numerous different applications and industrial sectors. However, when selecting a suitable gear pump for a specified application, manufacturers are often confronted with a lack of comparable measurement data for the desired combination of operating conditions and pumping fluid. Consequently, an estimation of the volume flow rate and the power consumption of a pump under the operating conditions of the application is necessary. In this context, this paper discusses the application of similarity on external gear pumps and presents its validation by means of measured pump characteristics. Seven gear pumps of different displacement volume are measured at different operating conditions varying pressure, rotational speed and the viscosity of the pumping fluid. The validation results prove that similarity is useful to represent a pump’s characteristic over a wide operating range. The prediction of the volume flow rate and the power consumption at a changed viscosity show good accuracy. However, the scaling of the pump characteristic based on the displacement volume show contradictory results.

Computer Prediction of Cyclic Excitation Sources for an External Gear Pump

1985 ◽  
Vol 199 (3) ◽  
pp. 175-180 ◽  
Author(s):  
K Foster ◽  
R Taylor ◽  
I M Bidhendi
Keyword(s):  
Computer Program ◽  
Gear Pump ◽  
Computer Prediction ◽  
Pressure Distributions ◽  
External Gear Pumps ◽  
Theoretical Predictions ◽  
Gear Pumps ◽  
External Gear Pump

A description is given of a computer program for investigating the performance of the external gear pumps under varying conditions with the special emphasis on the examination of pressure distributions within the pump, i.e. excitation forces for the vibration of the pump case and the variation in flow generated by the pump. Measurements are presented for the variation with time of tooth space pressure and the results are compared with the theoretical predictions from the computer program.

Methodology for the Evaluation of Gear Pump Performance

2020 ◽  
Author(s):  
Logan T. Williams
Keyword(s):  
Empirical Data ◽  
Pressure Rise ◽  
Operating Conditions ◽  
Volumetric Efficiency ◽  
Fluid Viscosity ◽  
Gear Pump ◽  
Pump Performance ◽  
Pump Speed ◽  
Multiple Parameters ◽  
Gear Pumps

Abstract Currently, most performance curves of gear pumps present volumetric efficiency as a function of one or more operating conditions. However, the nature of gear pumps is that volumetric efficiency is dependent on pump speed, pump pressure rise, and fluid viscosity. This dependency on multiple parameters impedes direct comparisons between pumps tested at disparate operating conditions or on different testbeds. A new method has been developed that formulates the volumetric efficiency as a function of a single parameter that captures pump speed, pressure, and fluid viscosity. The characteristics of the pump is then captured by curve fitting two constants to empirical data. This method allows extrapolation of pump performance beyond empirical data and direct comparison of the volumetric efficiency curves of two pumps tested under disparate conditions within a single plot. This work describes the analytical derivation of the methodology and the empirical data used for validations. Additionally, several possible applications of this method are presented.

Review of Gear Pump Development at NRL

2020 ◽  
Author(s):  
Logan T. Williams
Keyword(s):  
System Development ◽  
Design Guidelines ◽  
Lessons Learned ◽  
Naval Research ◽  
Gear Pump ◽  
Pump Design ◽  
External Gear Pumps ◽  
Gear Pumps ◽  
Original Goal ◽  
Small Form Factor

Abstract Research into hydraulic quadrupeds at the US Naval Research Laboratory (NRL) has created the demand for in-house development of miniaturized hydraulic components, including pumps. As part of this effort to develop a miniaturized hydraulic powertrain, external gear pumps were examined, designed, and iterated upon to create an efficient pump package with a small form factor (1.5 × 1.6 × 1.8 inches). The evolution of the pump design has touched every component of the pump and has resulted in many practical design guidelines, novel pump components, and improved pump analysis tools. The original goal of developing the capability for integrated hydraulic powertrain components, such as embedding the pump into the quadruped’s hydraulic manifold, was to enable further compaction and streamlined system development. An additional result of the project was the accumulation of gear pump design fundamentals and lessons learned that can benefit any pump designer.

The Flow Pulsation Analysis of an External Gear Pump

2011 ◽  
Vol 236-238 ◽  
pp. 2327-2331
Author(s):  
Yan Zhi Li ◽  
Li Huan Gao ◽  
Xiao Yang Tang
Keyword(s):  
Pulse Amplitude ◽  
Gear Pump ◽  
Flow Pulsation ◽  
Flow Ripple ◽  
Pump Flow ◽  
External Gear Pumps ◽  
Tooth Width ◽  
Different Types ◽  
Gear Pumps ◽  
External Gear Pump

In this paper, the theoretical flow ripple of an external gear pump is studied for pumps of similar size using different numbers of teeth on the driving and driven gears. External gear pumps with three different types of tooth profiles are studied. Nondimensional flowrates and fluctuation coefficients of gear pumps are discussed. By using the formula, flowrates can be calculated accurately and efficiently. Results indicate that: in the case of the same displacement (except teeth number and tooth width, other parameters of the gear pump are the same) the gear pump flow pulsation decreases with the increasing of the teeth number. We also concluded that changing tooth profiles on the driving and driven gear can get different pulse amplitude of the flow ripple.

Numerical Analysis of External Gear Pumps Including Cavitation

2012 ◽  
Vol 134 (8) ◽  
Author(s):  
D. del Campo ◽  
R. Castilla ◽  
G. A. Raush ◽  
P. J. Gamez Montero ◽  
E. Codina
Keyword(s):  
Contact Point ◽  
Sudden Change ◽  
Three Dimensional ◽  
Numerical Approach ◽  
Volumetric Efficiency ◽  
Complex Flow ◽  
Circular Pipes ◽  
External Gear Pumps ◽  
Hydraulic Machines ◽  
Gear Pumps

Hydraulic machines are faced with increasingly severe performance requirements. The need to design smaller and more powerful machines rotating at higher speeds in order to provide increasing efficiencies has to face a major limitation: cavitation. The problem is inherently three-dimensional, due to the axial clearances, the relief and circumferential grooves, and to the circular pipes through which the fluid enters and exits the pump. A simplified two-dimensional numerical approach by means of computational fluid dynamics (CFD) has been developed for studying the effect of cavitation in the volumetric efficiency of external gear pumps. The assumptions employed prevent from predicting realistic values of the volumetric efficiency, but show to be valid to understand the complex flow patterns that take place inside the pump and to study the influence of cavitation on volumetric efficiency. A method for simulating the contact between solid boundaries by imposing changes in viscosity has been developed. Experiments of unsteady cavitation in water and oil performed by other authors have been numerically reproduced using different cavitation models in order to select the most appropriate one and to adjust its parameters. The influence of the rotational speed of the pump has been analyzed. Cavitation in the suction chamber very effectively damps the water hammer associated to the sudden change of the contact point position at the end of the gearing cycle. At high rotational speeds, the volume of air becomes more stable, reducing the flow irregularity. When cavitation takes place at the meshing region downstream from the contact point, the volume of air that appears acts as a virtual second contact point, increasing the volumetric efficiency of the pump.

scholarly journals A Numerical Analysis of an Innovative Flow Ripple Reduction Method for External Gear Pumps

Energies ◽  
2021 ◽  
Vol 14 (2) ◽  
pp. 471
Author(s):  
Gianluca Marinaro ◽  
Emma Frosina ◽  
Adolfo Senatore
Keyword(s):  
Reverse Flow ◽  
Control Volume ◽  
Three Dimensional ◽  
Parameter Method ◽  
Gear Pump ◽  
Noise Emission ◽  
Flow Ripple ◽  
Commercial Code ◽  
Innovative Solution ◽  
Gear Pumps

In this paper, an innovative solution to minimize noise emission, acting on the flow ripple, in a prototype External Gear Pump (EGP) is presented. Firstly, a new tool capable to completely simulate this pump’s typologies, called EgeMATor, is presented; the hydraulic model, adopted for the simulation, is based on a lumped parameter method using a control volume approach. Starting from the pump drawing, thanks to different subroutines developed in different environments interconnected, it is possible to analyze an EGP. Results have been compared with the outputs of a three-dimensional CFD numerical model built up using a commercial code, already used with success by the authors. In the second section, an innovative solution to reduce the flow ripple is implemented. This technology is called Alternative Capacitive Volumes (ACV) and works by controlling and uniformizing the reverse flow, performing a consistent reduction of flow non-uniformity amplitude. In particular, a high reduction of the flow non-uniformity is notable in the frequency domain on the second fundamental frequency. The technology is easy to accommodate in a pump housing, especially for high-pressure components, and it helps with reducing the fluid-borne noise.

scholarly journals The Influence of Radial and Axial Gaps on Volumetric Efficiency of External Gear Pumps

Energies ◽  
2021 ◽  
Vol 14 (15) ◽  
pp. 4468
Author(s):  
Paulina Szwemin ◽  
Wieslaw Fiebig
Keyword(s):  
Fluid Flow ◽  
Volumetric Efficiency ◽  
Operating Parameters ◽  
Gear Pump ◽  
Cfd Model ◽  
External Gear Pumps ◽  
Flow Phenomena ◽  
Gear Pumps ◽  
The Impact ◽  
External Gear Pump

The design of gear pumps and motors is focused on more efficient units which are possible to achieve using advanced numerical simulation techniques. The flow that appears inside the gear pump is very complex, despite the simple design of the pump itself. The identification of fluid flow phenomena in areas inside the pump, considering the entire range of operating parameters, is a major challenge. This paper presents the results of simulation studies of leakages in axial and radial gaps in an external gear pump carried out for different gap shapes and sizes, as well as various operating parameters. To investigate the processes that affect pump efficiency and visualize the fluid flow phenomena during the pump’s operation, a CFD model was built. It allows for a detailed analysis of the impact of the gears’ eccentricity on leakages and pressure build-up on the circumference. Performed simulations made it possible to indicate the relationship between leakages resulting from the axial and radial gap, which has not been presented so far. To verify the CFD model, experimental investigations on the volumetric efficiency of the external gear pump were carried out. Good convergence of results was obtained; therefore, the presented CFD model is a universal tool in the study of flow inside external gear pumps.

Sign in / Sign up

Export Citation Format

Share Document