The article is about to the calculation of the main technical parameters of the directional air-hydraulic hood. It is accepted as a mathematical model of wave equations of hyperbolic type as applied to pressure pipelines of pumping stations, and analytical solutions of wave equations for different values of the polytropic exponents are proposed. Water hammer poses a danger to the normal operation of the main equipment of stations, control and measuring equipment, control devices and pressure pipelines. To damp the intensity of water hammer in the pressure pipelines of pumping stations, we have accepted an effective design of an air-hydraulic cap. When establishing the strength indicators of pressure pipelines against hydraulic shock, it is necessary to make an accurate calculation of the main parameters of the proposed design of the air - hydraulic cap. The article presents the results of analytical and experimental studies of the accepted cap design. At the same time, an analytical method is proposed for calculating the basic dimensions of the cap. The results of the proposed calculation procedure are in good corresponding with the experimental data. This confirms the reliability of the proposed analytical calculation method.
The article is about calculating the main parameters of air - hydraulic hoods with a diaphragm to reduce the emergency consequences of a water hammer, possible in the pressure pipelines of an irrigation pumping station. Based on the results of numerical studies by the method of finite differences of the proposed hydraulic shock absorber, dependencies were obtained based on a certain air in the absorbers, the total capacity of the cylindrical cap was determined to determine the main dimensions of the absorbers. Based on the results of numerical studies by the method of finite differences of the proposed hydraulic shock absorber, dependencies were obtained based on a certain air in the absorbers, the total capacity of the cylindrical cap was determined to determine the main dimensions of the absorbers. To determine the economic dimensions of the proposed cap design, comparative calculations of numerical experiments with experimental data prove the reliability of the proposed dependencies using the finite difference method.
The article is devoted to the study of the propagation velocity of the rarefaction wave and the compression wave, taking into account the two-phase (water + air) flow in the long pressure pipelines of pumping stations. Hitting speed is the main parameter of water hammer. Water hammer poses a danger to the normal operation of the main equipment of stations, control and measuring equipment, control devices and pressure pipelines. When establishing the strength indicators of pressure pipelines, it is necessary to make an accurate calculation of the shock wave speed, taking into account the dosed amount of not dissolved air in the water. The classical theory of water hammer is based on the gamogenic model and does not take into account air in the liquid. This circumstance leads to a decrease in the accuracy of calculating the velocity of the shock wave and water hammer. The article presents the results of analytical studies of the shock wave velocity, taking into account the two-phase pressure flow. At the same time, an analytical method for calculating the velocity of the shock wave is proposed. The results of the proposed technique are in good agreement with the graphical solutions of this problem and with experimental data.
The article provides an analysis of scientific papers devoted to the study of hydraulic shock absorbers used in pumping stations with long pressure pipelines. The efficiency of pumping stations depends on ensuring trouble-free operation - the reliability of pressure-hydraulic systems. The reliability of pumping units and long pressure pipelines is ensured using the proposed designs of hydraulic shock absorbers. In the experimental study of hydraulic shock absorbers, modern scientific instruments were used. The authors of this work have developed a special pressure sensor to record changes in hydrodynamic pressure during hydraulic shock. The paper presents the results of experimental studies of hydraulic shock absorbers with and without a diaphragm. At the same time, a reliable agreement was obtained between the results of calculations of hydraulic shock absorbers with and without a diaphragm using the proposed method with experimental data. The performed research experiments prove that the damper with a diaphragm is a very effective and economical water hammer damper for long pressure pipelines of pumping stations with the values of the polytropic coefficient n=1.2. Calculations and experiments confirm that the proposed method for calculating an absorber with a diaphragm can be applied to calculate an absorber without a diaphragm.
The article provides an analysis of scientific papers on the study of a hydraulic shock absorber - an air-hydraulic cap, shows that at present there is no consensus on the choice of the numerical value of the polytropic coefficient n. In practice, during the operation of pumping stations with long pressure pipelines, in the event of a sudden power outage, water hammer often occurs to the motors of the main pumps. To prevent this phenomenon, it is convenient to apply a hydraulic shock absorber. The accuracy of calculating the shock absorber depends on the reliable value of the coefficient n. The correct selection of the numerical value of the polytropic coefficient n provides for determining the optimal dimensions of the proposed hydraulic shock absorber. There are different opinions about the choice of the numerical value of n among scientists. N.E. Zhukovsky, when calculating the hydraulic shock absorber, takes n = 1.41. V.S. Dikarevsky accepts n=1.0. Therefore, the rationale for the correct choice of the numerical value of the polytropic coefficient for calculating the absorber in the case of water hammer is very relevant. The paper presents the results of experimental studies of the polytropic coefficient n in a hydraulic shock absorber from a decrease in pressure. When conducting experiments on the study of the absorber, modern scientific instrumentation was used. At the same time, the obtained results of the experiments confirm that the variability of the value of the polytropic coefficient during hydraulic shock in the cap and the correctness of the recommendation of D.A. Fox. The conducted studies prove that the polytropic coefficient has a strictly polytropic character.
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