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Документ Modeling of the external magnetic field of electric machines(Національний технічний університет "Харківський політехнічний інститут", 2024) Levchenko, Larysa; Ausheva, Nataliia; Karaieva, Nataliia; Glyva, Valentyn; Burdeina, NataliiaThe goal of the work. Proposals for methods of solving systems of linear homogeneous and nonhomogeneous differential equations with constant and variable coefficients that defined in interval form and intended for modeling exchange processes in multicomponent environments. Research subject: systems of linear homogeneous and nonhomogeneous differential equations with constant and variable coefficients defined in interval form. Powerful electric machines – such as electric generators, electric motors generate a magnetic field of great tension. These fields negatively effect on personnel and can to violate the stability of electronic equipment. To determine safe areas for workers, laying communication cables and placing sensitive electronic equipment, it is advisable to model the propagation of magnetic fields of electrical machines. This will make it possible to rationalize the placing of electrical equipment at design stages. The most common high-power electrical machines are four-pole electrical machines with a dipole-quadrupole structure of the external magnetic field. The purpose of the research is a development of models of the propagation of the external magnetic field generated by alternating current electric machines. Results of the research: it is substantiated that to simulate the propagation of the magnetic field of electric machines, it is advisable to use the Gauss equation for the magnetic scalar potential. This will make it possible to take into account the required number of spatial harmonics of the magnetic field to ensure an acceptable calculation error. An electric machine is considered in a spherical approximation. Calculations were carried out in spherical coordinates. The distances were determined in relative radii of the electric machine – the ratio of the radius of the machine to the definition of field strength. The calculations were made for two planes of spherical coordinates and a three-dimensional image was obtained. As a result of the simulation, it is possible to determine the magnetic field strength of a four-pole electric machine at selected distances and directions around the electric machine with the required accuracy. It has been established that there are points of zero external magnetic field strength around electrical machines. Verification of the simulation results was carried out using the method of full-scale measurements of the magnetic field strength around a real four-pole machine. The measurement results showed acceptable agreement with the calculated data. Conclusions: the chosen approach and the results of modeling the propagation of the external magnetic field of electrical machines can be used to design the placement of electrical equipment, taking into account the requirements for electromagnetic safety and electromagnetic compatibility of technical equipment.Документ Methodology for modeling the spread of radioactive substances in case of an emergency release at a nuclear power plant(Національний технічний університет "Харківський політехнічний інститут", 2023) Levchenko, Larysa; Biliaiev, Mykola; Biliaieva, Viktoriia; Ausheva, Nataliia; Tykhenko, OksanaThe methodology for modeling the propagation of accidental releases of radionuclides from a power unit of a nuclear power plant has been developed. The calculation method takes into account the most critical factors propagation cloud ─ wind direction and speed, the intensity of the release radionuclides change: semi-continuous release, long-term release, instantaneous release. Diffuse processes and the presence of interference in the form of buildings were also taken into account. To solve the modeling equation of the aerodynamic model, the velocity potential equation is solved. The use of this equation instead of the traditional Novier-Stokes equation makes it possible to rationalize the calculation process in terms of the speed obtaining simulated data. To build a numerical model, a rectangular difference grid is used. The velocity potential and the quantities values of volumetric activity are determined at the centers of difference cells. The value of the airflow velocity vector component is determined on the sides of the difference cells. A finite-difference splitting scheme is used for numerical integration of the equation convective-diffusion transfer radionuclides. A computer code was developed on the basis of the constructed numerical model, the programming language Fortran was used. The approach used makes it possible to reduce the time for obtaining one scenario of an accident development. The cloud propagation dynamics determining is carried out almost in real time. This allows you to quickly respond to changing situations and make adequate decisions.