Fundamentals of the Theory of Power Pulse Device
The article discusses a mathematical model of a power impulse device, which allows you to select the characteristics of the ejected liquid jet, such as the velocity at the moment of ejection, the pressure created in the nozzle of the power impulse device, etc., by changing the parameters of the device. A feature of the proposed mathematical model, which significantly distinguishes it from the previously considered models, is that the model was considered for the case of unsteady motion. This state of the medium in a power impulse device is the most characteristic, therefore the results obtained are more general. It is shown that, in contrast to the steady motion of a liquid, in the case of unsteady motion, an additional term appears, which can be defined as a head having an inertial character. It can be seen from the proposed mathematical model that the presence of an inertial head leads to the appearance of a flow deceleration effect, which, in turn, leads to an increase in the total liquid head in the direction of the flow. The pressure generated in the barrel acts against the direction of the hydraulic resistance. All of the above is applicable only for a certain moment in time or for the case when the acceleration of the fluid is constant. If the acceleration changes, then the action of the heads along the fluid flow is a function of time. This circumstance makes it possible to apply the result obtained with unsteady motion to create devices that form a high-pressure jet. A distinctive feature of the considered model is that it analyzes the behavior of the fluid in the power impulse device for two cases: 1. the volume of fluid in the barrel of the power impulse unit is greater than the volume of the nozzle; 2. the volume of fluid in the barrel is less than or equal to the volume of the nozzle. The results of the analysis showed that in the first case, the initial velocity of liquid ejection significantly exceeds this velocity in the second case. That is, it is the first case that is of practical importance.