Power unit with adjustable jet pump

The article analyzes two ways changing the supply of the hydraulic power supply unit - with the help of a throttle and jet pump with a variable nozzle outlet area. The unit with a jet pump, while maintaining the simplicity and high reliability of throttle control, is proved to be more efficient. Its application improves the operation of the main pump and increases the efficiency of the installation by more than 20 percent. In a unit with a jet pump (ejector), high-pressure fluid is supplied to the nozzle via a branch from the discharge port of the main pump, and low-pressure fluid is supplied through the drain line of the hydraulic system. In the flow part of the jet pump there is an energy exchange between the flows. The total flow jet pump with a pressure He is fed to the suction side of the main pump. Changing the fluid supply unit power is carried out by regulating the flow area of the nozzle of the jet pump. When the nozzle is fully opened, the entire flow (or part of it) from the main pump returns through the ejector to its entrance, bypassing the hydraulic system. When closing the flow area of the nozzle, the entire flow of the main pump enters the hydraulic system. If the heads of the hydraulic power units with throttle and ejector versions are the same, then the required head of the main pump in the unit with an adjustable jet pump will be lower Consequently, the power to drive the pump will decrease. The authors analyze the work power units in dimensionless coordinates neglecting head losses in connecting lines. The feed main pump and its pressure serve as the source (basic) values.