Calculation of the optimal time of liquid projectile outflow from the nozzle of a pulse ejector

This article is devoted to jet pumps, due to the simplicity of their design, they are widely used in the energy, metallurgical, chemical, oil and gas industries. The majority of researchers involved in inkjet devices claim that the use of jet interrupting devices is more effective than the classical scheme of an inkjet device. The working process of an ejector with an intermittent jet or a pulsed ejector consisting of an acceleration phase and a deceleration phase is considered. This article discusses only the first part of the workflow - the acceleration phase, which occurs when the nozzle channel is opened. In the liquid acceleration phase, the energy required to perform the work is transferred. The study of the acceleration phase will allow calculating the optimal time for the liquid to flow through the nozzle, which will improve the extreme characteristics of the ejector with an intermittent jet, reduce energy costs and increase the efficiency of the jet device. The article describes the energy equation for the unsteady flow of liquid through the nozzle in a differential form, an analytical dependence of the instantaneous flow rate of liquid through the nozzle on the pressure drop at the nozzle, the density of the liquid, the inertial length of the nozzle, the nozzle resistance coefficient and the expiration time is obtained. The dependences of the instantaneous flow rate on the expiration time for different values of the pressure drop and the inertial length of the nozzle are illustrated. Based on the obtained dependencies, it is possible to see the effect of the expiration time on the instantaneous velocity and energy of a liquid projectile. A technique has been developed to determine the optimal time for the liquid to flow through the nozzle and an example of calculating this time is given.