The purpose of this monograph is to present and systematize the theoretical and practical concepts of the physical principles of operation, design principles and methods for calculating and analyzing the parameters and modes of operation of individual functional elements (working bodies) of technological schemes (including elements of the main and auxiliary equipment) of turbines of thermal and nuclear power plants. The methodology of theoretical analysis of the thermodynamic cycles of the working substance in the flow path of the turbines of TPPs and NPPs implies an in-depth understanding of the laws of thermal-mechanical and heat exchange processes occurring on the elements of the blade apparatus (including nozzle and rotor blades) of the turbine stage. The methodology of this monograph is based on the basic laws and methods of technical thermodynamics, the theory of heat exchange processes and mass transfer processes. Methods of continuum mechanics hydrodynamics and gas.The manual is intended for students of the specialty "Heat power engineering" and also can be used by undergraduates of the specialty "Heat power engineering".