DYNAMICS OF PNEUMATIC DRIVE. LECTURE CYCLE. “LONG” PNEUMATIC/HYDRO PIPE LINES

Abstract

The paper considers examples of the manifestation of non-stationary hydromechanical processes that occur in machines and apparatus, control and regulation systems, while the load is the fluid itself. The application of pneumatic servo wires during operation under conditions of non-stationary hydromechanical load is given. The criterion for the “long” pneumo/hydro pipe line is determined. Equations are derived that make up the mathematical model for the pipe line in the case of a weakly compressible fluid and in the case of a highly compressible fluid. Equations are given for the non-stationary coefficient of friction along the length for the values of the Reynolds numbers Re = 3100...28 000. The derivation of the transfer matrix terms is given for a long pipe line in the case of a weakly compressible fluid, defined as a fourpole. In the case of a highly compressible fluid, transfer functions are derived that uniquely establish the relationship between the parameters at the input and output of the pipe line when changing the parameters at its output. An example of reducing pressure peaks in a long pipe line using a pneumohydraulic accumulator is considered. The basic equations are derived that allow performing mathematical modeling of transients in pipe lines with an installed accumulator. The criteria for selecting the volume of a pneumohydraulic accumulator are determined based on the dynamic properties of the entire system under consideration. The scientific novelty of the results of the analysis of nonstationary dynamic processes presented in the paper is that the influence of system parameters on wave processes in them is considered, and as a result, they have practical application, for example, for aviation hydraulic systems or in the study of oil transportation and production issues. In addition, this work is based and is implemented as a course of lectures of the course “Dynamics of Pneumatic drive”, is red by the author at the Bauman Moscow State Technical University at the Department of “Hydromechanics, Hydraulic Machines and Hydropneumoautomatics” (E10), as part of the preparation of masters in the specialty 05.04.13 “Hydraulic machines and hydropneumatic drives”.