Zhukov A. Optimization of the weight and dimensions of large DC machines

The dissertation work is devoted to the urgent issue of optimizing the mass-dimensional parameters of large electric DC machines by creating new methods for three-dimensional calculation of the thermal and stressed-strained state of the units and parts of the active and structural parts of these machines. During the research, calculations of the cooling air movement and temperature distribution in the collector and brush-holders device area of the DC electric motor were performed in order to optimize its mass-dimensional parameters and to ensure the possibility of reliable operation after the introduction of a forced ventilation system of these units. Calculations of the stressed- strained state of the rotor elements of the electric motor were also performed in order to confirm the possibility of performing optimization work related to the machining of surfaces and thermal fitting of elements. The purpose of the dissertation is to develop methods and algorithms for scientific substantiation of complex solutions for optimizing the mass and dimensions of large DC machines using modern finite element methods and computational hydrogasdynamics. Scientific novelty of the work: 1. A new method for analysing the thermal state of structural elements of large DC machines has been created with the solution of a set of problems of air movement and heat conduction in a three-dimensional formulation using the finite volume method, which is distinguished by a more accurate assignment of boundary conditions in the gradient problem of heat release and heat transfer coefficients in a three-dimensional formulation. 2. An improved algorithm for creating an optimized finite volume mesh for a ventilation model using basic tetrahedral components, characterized by the condensation of components in separate areas of the channels, due to detailed design factors. 3. An improved algorithm for optimizing the mass and dimensions of electric-mechanical equipment with determining of the stress-strained state of the restored units, based on the parameters of electric-magnetic efficiency and maximum technological capability. Practical significance of the obtained results: 1. A justification is provided for optimizing weight and dimensions by implementing a forced ventilation system for the collector and brush assembly of a DC machine, ensuring their proper thermal state. 2. The possibility of optimizing the mass and dimensions of an electric machine based on the analysis of the stress-strained state of the restored parts, ensuring its further reliable operation, has been confirmed.