Вісник № 02. Гідравлічні машини та гідроагрегати
Постійне посилання колекціїhttps://repository.kpi.kharkov.ua/handle/KhPI-Press/56720
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Документ Influence of hydrodynamic characteristics of water passage elements on energy parameters of pump-turbine(Національний технічний університет "Харківський політехнічний інститут", 2021) Tynyanova, Irina; Rezvaya, Kseniya; Drankovskiy, ViktorUkraine has sufficient potential for the development of renewable energy sources. Renewable energy of our country is actively developing. The demand for accumulating hydropower services will grow. This is due to the requirements of modern energy systems to align the schedule for operation in peak load zones. The solution to the problem of creating highly efficient equipment for pumped storage power plants largely depends on the correct selection of the geometry of the water passage elements of the reversible machine, which provide the required level of its energy parameters. The paper deals with the issues of modeling the hydrodynamic characteristics of the blade systems of a reversible hydraulic machine. Changes in energy parameters in the range of basic operating modes of the hill-chart are largely due to changes in the hydrodynamic characteristics of a reversible hydraulic machine. The general approach to describing the hydrodynamic characteristics of blade systems is based on the use of dimensionless parameters characterizing the flow in the characteristic section of the water passage. Expressions, which establish the relationship between the hydrodynamic characteristics and dimensionless complexes and express the general laws of the interaction of the flow with the runner of a reversible machine, are given. The influence of the hydrodynamic parameters of blade systems on the formation of the energy characteristics of a reversible hydraulic machine is considered. Analysis of the hydrodynamic characteristics of individual elements of the water passage allows to analyze their influence on the energy characteristics of a reversible hydraulic machine. The results of such an analysis are the basis for solving a wide range of issues that arise when designing a reversible hydraulic machine. This paper presents the calculations of the energy characteristics for the water passages of reversible hydraulic machines ORO200, ORO500. The calculated data indicate the decisive influence of the hydrodynamic parameters of the spatial lattice on the parameters of the optimal regime.Документ Calculation of the spatial flow in the francis high-head turbine using the CFD software package(Національний технічний університет "Харківський політехнічний інститут", 2021) Krupa, Y. S.At present, the development of software packages for calculating computational fluid dynamics problems has reached a high level of efficiency, accuracy and flexibility, with their help it is possible to solve the most diverse and complex problems. All modern software packages for computational fluid dynamics solve the problems of continuum mechanics using models based on the Navier-Stokes equations. These models are based on three conservation equations: conservation of mass, conservation of momentum and conservation of energy. A numerical simulation of the spatial flow of a high-head radial-axial hydraulic turbine Fr 310 was carried out for two variants of the flow path – with an runner with 15 blades (modification 1) and with 17 blades (modification 2), using the OpenFOAM software package. The OpenFOAM software package is one of the most used products designed to solve fluid dynamics problems and is distributed under a free GPL license (General Purpose License). The process of solving the set hydrodynamic problems using the CFD (Computational fluid dynamics) software package includes the following stages: creating a three-dimensional model of the object under consideration using a computer-aided design system; construction of a computational grid with the required parameters; selection of a mathematical model that most accurately describes the working process in the flow parts of hydraulic machines; selection of a suitable turbulence model; setting boundary conditions. A visualization of the results of a numerical study of two modifications of the Fr 310-V-100 hydraulic turbine is presented. A method for calculating hydraulic losses in the flow path of a hydraulic turbine is presented. The analysis of the results of numerical simulation was performed. This analysis showed that the modification of a hydraulic turbine with a runner with 15 blades is better in terms of efficiency than the modification with 17 blades. Comparison of the two modifications was carried out exceptionally by the values of the hydraulic efficiency of the hydraulic turbine.Документ Modeling the shape of tool wear during cutting of the composite materials(Національний технічний університет "Харківський політехнічний інститут", 2021) Khavin, G. L.The process of the shape changing for the tool cutting edge in relation to the initial state due to wear during cutting of polymer composite materials is considered. Modern experimental achievements in the study of the nature of changes in microgeometry in the process of wear are analyzed. Based on the analysis of experimental data, an assumption was made about a slight change in the initial rake angle and the rounding radius of the tool tip during wear. On this basis, a conclusion was made about the one-parameter nature of the change in the geometry of the tool cutting edge in the process of interaction with the composite. A model for removing the volume of material is proposed, which makes it possible to determine the total loss of weight of the tool during the cutting process. The relationship between flank wear, dimensional wear and change in tool weight is shown. A geometric model is used to determine weight loss. The proposed assumptions in the mathematical model are discussed. As a first approximation in the calculations, a simplified definition of the worn area near the tool tip is proposed. A generalized algorithm for step-by-step calculation of the tool tip geometry and the inverse problem of weight loss during operation are considered.