Numerical and Experimental investigation of leakage pattern within an external gear pump

Gear pump is one the most common types of static type (positive displacement) pumps with properties such as small size and safe performance. These pumps are mainly used for handling high pressure fluids and flow measuring in hydraulic systems. The most important weakness of this type of pump is high leakage in high working pressures. So, it is important to study the leakage types and the ways to eliminate them in order to decrease the amount of energy lost. In this study, an external gear pump has been studied numerically, analytically and experimentally. Using FLUENT software, the pump leakage, efficiency and power consumption are studied numerically and then have been compared with the experimental data. The numerical results have a good agreement with the experimental data. The results show that the leakage due to a suitable central clearance does not reduce the pump performance. Moreover, this clearance causes the fluid to convey from the space between gears to the high pressure outlet zone without using any decompression slots on the side bearings of the pump. As a result, the flow rate and the pump overall performance are improved.