The main results of the study of hydraulic losses in the suction line and mechanical damages of the impellers of pumps due to cavitation-abrasive wear are given in the article. The scientific task of using theoretical bases for justifying factors affecting the wear rate of pump parts is being solved. On the basis of these theories, a technique is proposed for calculating the wear rate of the elements of the flow-through part of the pumps. During the experimental studies, standard methods of laboratory-bench testing of pumps were used. The operating modes of pumps with minimal wear of their parts are established. Poor hydraulic flow conditions with swirl zones cause an increase in energy losses and a redistribution of flow rates across sections. Wear the parts that are flowing directly proportional to the concentration in the sediment flow, the cube of the flow velocity, the time of action on the pump units. The presence of unsteady vortex regions, especially when the effect of eddy formation increases, leads to fluctuations in the velocities and pulsations of the flow pressure. Cavitation in the pump occurs when the operating modes of the pump differ from the nominal. The increase in volumetric efficiency, the improvement of hydraulic flow conditions to the pump impeller and the reduction of cavitation wear were achieved by the authors in a new pump design that contains guide planes fixed to the throttle plate parallel to the suction nozzle axis with an elastic outer surface. In the same areas of constructive improvement of pump assemblies, it is necessary to search for ways to reduce the negative impact of cavitation and hydroabrasive erosion on the life of pumps.
Based on the laws of classical mechanics, in particular, the law of conservation of momentum, the paper describes the developed mathematical model of signal propagation during vibration diagnostics. At the beginning, the problem of signal propagation was investigated, which was reduced to solving the problem of wave propagation. According to the analysis of experimental results investigated, that the attenuated nature of the signals must be taken into account. For this purpose, a mathematical model has been developed, which allows to solve the problem of the propagation of damped signals. Comparative analysis allows to conclude that the constructed model is adequate.
The aim of the research is to increase the efficiency of pumping stations operation by improving the methods of uniform spreading of the flow from the front chamber and the water intake of the pumping station and the development of constructive measures to improve the hydraulic conditions of the flow supply to the pumps. This goal is achieved by the fact that the device for supplying water to the water intake contains guiding elements. The improvement of the method of hydraulic calculation of the flow in the front chamber and the water intake chamber is carried out on the example of the head pumping station of the Jizzakh cascade. In the process of research, standard methods of full-scale and bench tests of pumps, methods of mathematical and hydraulic modeling, statistical processing of results and the creation of mathematical models based on the laws of hydromechanics were used. The project substantiates the choice of a technical solution to improve the hydraulic structure of the flow in front of the impeller of the pumps of the Jizzakh head pumping station. The authors have developed new technical solutions, including an element for influencing the flow, installed in the water intake chamber of the pumps. This makes it possible to expand the ranges of stable, cavitation-free operation of the pump, to ensure an increase in the reliability of water supply to the pumping station, without resorting to complex and expensive reconstruction measures.
The large pumping stations (PS) planned for reconstruction in our republic in terms of consumption, power-to-weight ratio, and controls are the largest in the world: failure of them even for a small period of time can lead to enormous damage. Therefore, the formulation and solution of theoretical problems in the operation of these facilities, taking into account the reliability indicators, is an extremely important national economic task. Until now, the design of the National Assembly, including large ones, has been conducted without taking into account the quantitative index of reliability. The value of reliability has long been underestimated, and error correction required significant costs. Currently, increasing the efficiency of the operation of pumping stations is associated with the development of energy-saving and resource-saving technologies. Diagnostics is one of the modern and perfect ways to determine the main malfunctions that occur in pumping units. The main goal of diagnosing the technical condition of pumping units is to preliminarily identify the occurring malfunctions in it and ensure durability, reliability, reliability, and operational efficiency. The article presents the effect of vibration on pumping units and analysis of methods of vibration diagnostics, information is given on the possibility and advantages of devices for continuous vibration diagnostics.
The aim of the authors’ research is to improve the hydraulic conditions for supplying the flow to the impeller and to reduce the cavitation wear of the pump working bodies. This goal is achieved by the fact that the device for supplying liquid at the inlet to the pump contains guide elements in the form of flat plates mounted on the axis of the suction pipe. With further modernization, the pumped liquid was stabilized after the impeller, with the elimination of vortex flows along the entire flow path of the pump due to new elements in the pump chamber. The problem is solved by the design of a straightening blade with a free cross-sectional area of the wall channel less than the inner channel. The research methods include the conduct of field and laboratory studies using modern technical means of observation. Long-term experimental work carried out at large pumping stations investigates interconnected systems of connecting structures and pumps. The stability function is determined as a result of taking into account a number of factors: the external environment, technological properties of systems and operational requirements. The change in the critical, from the point of view of the emergence of cavitation, the value of the pump supply from different densities of the pumped liquids was established as a result of bench tests. In the experiments, the cavitation erosion of the growth was compared with analogs in the average 90-100 times. The ratio of the performance of the surface tension force to the density for mercury and water at a temperature of 15° C turned out to be equal to 91. As a result of the development of a new design together with Joint-Stock Company SUVMASH and the method of calculating the working parts of the pump with a minimum wear rate of the pump with a minimum wear rate of 5%.
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