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Investigation of leakage within an external gear pump with new decompression slots: numerical and experimental study

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Abstract

Gear pumps are amongst the most common types of positive displacement pumps. Having advantages such as small size, continuous and smooth output flow and high performance, these pumps are mainly used for handling high pressure fluids and flow metering. But the most important weakness of these pumps is the severe radial leakage at high pressures. Hence, it is important to study the leakage types and the methods of eliminating them in order to decrease any performance lost. In this study, a simple external gear pump has been studied numerically, analytically and experimentally. Using a commercial software, the pump leakage, volumetric efficiency and power consumption are studied numerically with respect to cavitation modeling. The numerical result shows good agreement with the experimental and analytical data. A new set of decompression slots on the gears teeth is introduced which eliminates the weakness of the prior methods. The results show that it has eliminated high pressure pulsations and catastrophic cavitation during the meshing process of the gears without increasing the radial leakage. As a result, the pump overall performance increases with smoother outflow. Also, the effect of gear teeth radius/teeth tip length on the pump performance has been studied in various working pressures within a case study. This investigation can be an essential and simple tool to design high performance gear pumps.

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Abbreviations

b :

Gear width

COP:

Coefficient of performance

CP:

Contact point

D :

Gap height

\( \Delta P \) :

Pressure difference

dP :

Minor change in pressure

dx :

Minor change in length

H :

Half of the gap height

HP:

High pressure

L :

Radial leakage gap length

LP:

Low pressure

\( \dot{m} \) :

Mass flow rate

n :

Effective average teeth number

N :

Cells number

P :

Pressure

Q :

Volumetric flow rate

r :

Gear tip radius

Re :

Reynolds number

u :

Radial velocity

U :

Tip velocity of the gear

V :

Fluid velocity

\( \dot{W} \) :

Power

η :

Volumetric efficiency

\( \eta_{\text{d}} \) :

Displacement efficiency

\( \eta_{\text{l}} \) :

Leakage efficiency

µ :

Dynamic viscosity

ν :

Kinematic viscosity

ρ :

Density

ω :

Angular velocity

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Authors and Affiliations

  1. School of Mechanical Engineering, College of Engineering, University of Tehran, Tehran, Iran

    Farhad Sedri & Alireza Riasi

Authors
  1. Farhad Sedri
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  2. Alireza Riasi
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Correspondence to Alireza Riasi.

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Technical Editor: Jader Barbosa Jr., Ph.D.

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Sedri, F., Riasi, A. Investigation of leakage within an external gear pump with new decompression slots: numerical and experimental study. J Braz. Soc. Mech. Sci. Eng. 41, 224 (2019). https://doi.org/10.1007/s40430-019-1717-8

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  • DOI: https://doi.org/10.1007/s40430-019-1717-8

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