Підвищення ефективності робочого циклу паливного шестерного насоса високого тиску за рахунок використання струминного насоса в якості ступеня підкачування

Abstract

This article analyzes the possibility of increasing the efficiency of the gear pump operating cycle by using a jet pump as a booster stage. The design of gear pumps is performed for one mode, and most often, it is a mode with minimum speed and high consumption relative to rotation speed. For gas turbine engines, this is the take-off mode, in which the aircraft operates for a few minutes of the entire flight cycle. In other modes, the pump capacity is excessive, reaching more than twice the value in some operational conditions. Due to the excess capacity, overflow valves are used to synchronize the operation of the engine and pump. This approach is a classic solution, but it creates additional mechanical losses and, as a result, reduces the efficiency of the operating cycle of the pump. Therefore, there is a need to improve the matching of engine requirements and pump performance. In this article, a solution that can improve the operating cycle of pumping units within the framework of a classical drive box assembly was analyzed. In the introductory section, the generalized flight cycle of a transport aircraft is analyzed. Based on the results, the modes were determined for which the design calculations of the jet pump were performed. First, the relative characteristics of pressure increase and efficiency are considered. The geometric and operational boundary conditions are accepted considering the fuel overflow relative to the generalized flight cycle. The obtained characteristics are used as a basis for selecting the geometric ratio for the modes with the highest pressure and efficiency. Based on these results, the geometric dimensions of the main sections and the value of the pressure increase at the outlet of the jet pump were obtained. Based on the characteristics of the pressure increase behind the jet pump, the relative characteristics of the reduction in power consumption in the gear pump shaft were obtained. Considering the level of overflow and operating time, the use of a jet pump will save about 50% of the energy input. This is a direct improvement in the operating cycle, and the increased pump inlet pressure will also reduce bearing wear, increase cavitation resistance, and reduce wear from cavitation erosion.