Comparative analysis on relief grooves of high-speed and high-pressure aeroengine fuel gear pumps

The relief groove is the most effective measure to alleviate oil trapping of gear pumps; therefore, its design directly affects the working efficiency and service life of the gear pump. This paper presents a performance analysis method for relief grooves based on computational fluid dynamics. A comparative study was conducted to evaluate the performance of different structural forms of relief grooves, focusing on technical indicators such as trapped oil pressure, gas volume fraction, outlet flow rate, and the flow rate non-uniformity coefficient. The results show that the relief groove F, with a flow non-uniformity of only 5.25% and a trapped oil pressure peak of 18 MPa, outperforms the rectangular, circular, and unloading slot E in terms of overall performance, exhibiting advantages of low trapped oil pressure, high volumetric efficiency, and high flow quality. These characteristics make it well-suited for the design of high-speed and high-pressure fuel gear pumps. In addition, increasing the size of the relief groove and positioning it towards the low-pressure chamber can reduce cavitation, oil entrapment, and flow pulsation. Designing the new unloading slot F with these factors in mind can improve its overall performance.