It has been established that in order to study thermo- and electrophysical phenomena in wet steam turbines, studies of the wet steam flow volume charge effect on its dielectric and thermophysical properties have recently been carried out at A. Pidhornyi Institute of Mechanical Engineering Problems of the National Academy of Sciences of Ukraine. According to their results, it was established that the most representative electrophysical parameter, which allows to evaluate changes in the thermophysical properties of steam, which occur under the action of its own volume charge, is its dielectric constant. It is assumed that the value of the dielectric constant of an electrified steam can be significantly different from the value for a neutral steam, and a mathematical assessment of its possible change is made. It has been confirmed that the influence of electrophysical phenomena caused by the wet steam flow electrification is significant, but is not taken into account in the existing physical and mathematical thermodynamic models of the steam expansion process. It is proved that in order to clarify the main thermodynamic parameters and calculated characteristics of the electrified wet steam flow, it is necessary to determine how its dielectric constant changes. On the basis of the analysis, the relevance of experimental determination of the dielectric constant of a wet steam flow with a volume charge in order to obtain the dependence of its change on the temperature and pressure of the flow, as well as the density of the volume charge, is substantiated. To perform the research, a gas dynamic laboratory plant, which allows to obtain a wet steam flow with a volume charge, was used. The internal space of the flow part of a real wet steam turbine has a significant size and allows the formation of a flow with a volume charge of a complex spatial configuration and structure. It is emphasized that in the flow part of the plant of a small volume, in contrast to the turbine flow part, significant technical difficulties arise when organizing the conditions for the occurrence of a wet steam flow with a volume charge. Taking this into account, at the first stage, it was decided to conduct a study of a steam flow with a volume charge flowing into the atmosphere in a laboratory room with a sufficient volume to form its spatial structure. To estimate the value of its dielectric constant, the inductive method (L-method) of determining dielectric properties, in which the substance under study is introduced into the inductive solenoid cell, was chosen. Experiments were conducted and, according to the obtained data, it is possible to make a preliminary assessment of the change in dielectric constant in the presence of a volume electric charge in the steam flow

The effect of steam electrification on the operation of a wet steam turbine, as well as the main processes sensitive to the electrification of the working fluid are considered in the paper. The types of additional losses caused by electrification are indicated. It is noted that these losses are not counted in the currently existing physical and mathematical models, since data on electrification are not taken into account and there is no possibility to make a clear theoretical description of the electrophysical model of a neutral steam even. In this regard, a simplified qualitative physical model of the electrophysical processes that occur during the electrification of the steam flow in the turbine was studied. Based on this, an assumption regarding the properties of the space charge in the steam flow, which is the source of the electric field and determines its intensity and spatial distribution in the flow part, is made. A qualitative analysis of the effect of the space charge field on the physical and thermodynamic properties of the steam flow was carried out with the set assumptions. It is proposed to perceive the process of steam polarization in the space charge field as the main result of its influence, and the dielectric constant of the steam – as the most representative parameter characterizing the thermodynamic state, including with the field influence. The thermodynamic relations of the operation of the dielectric in an electric field are given. The relation between the dielectric constant of steam and the change in the internal energy of the working fluid, its entropy and free energy is shown. It is theoretically substantiated that the influence of the electric field also leads to a change in the isobaric heat capacity and enthalpy. It is concluded that the process of expansion of the wet steam flow of charged steam in the turbine unit can be accompanied by a change in the main thermodynamic parameters of the working fluid, and therefore, its design characteristics can change, including the losses that occur in the process of expansion. On the basis of previously obtained experimental data on real turbines, a numerical assessment of the change in the thermodynamic parameters of the working fluid under the influence of an electric field is carried out. The performed numerical studies unequivocally indicate the need to take into account the phenomena caused by the electrification of the wet steam flow in the low-pressure cylinder in the existing physical and mathematical thermodynamic models of the wet steam expansion process, as well as to clarify the main thermodynamic parameters and calculated characteristics of the flow of electrified wet steam depending on the change in its dielectric constant.

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The design and development processes of gas turbine engines rely on the usage of mathematical models representing the physics of engine functioning processes. One way of increasing the validity of a mathematical model is its identification based on engine test results. The identification of mathematical models of modern power-generating gas turbine engines (GTEs) presents a demanding and time-consuming task due to the necessity to identify the main controlled engine parameters determined in the course of experimental studies depending on a large number of the parameters that are not controlled during the experiment. In this regard the actual direction of reducing the labour intensity of the process of mathematical model identification is using identification program complexes. The object of the study was to solve the problem of structural-parametrical identification of the power-generating GTE functioning model detailing the turbine flow path calculations to the level of blade rows in order to obtain the GTE mathematical model that describes the characteristics of a real engine with given accuracy. To achieve the objective, the following problems were solved: variable parameters, controlled parameters and characteristics, ranges of their variations were selected from the total number of the mathematical model input data, the objective functions were defined; the task of the parametric identification according to the results of bench tests through GTE operating modes was performed; analytical approximating dependences for correcting coefficients (variable parameters) were obtained; structural-parametric identification of the mathematical model was performed. The novelty of the obtained results is the identification of the mathematical model of the nonlinear component GTE of the second level performed without model linearization (without its level lowering) by using the Optimum software packages. The methodological approach for the parametric identification of the mathematical model is proposed. This approach allows reducing the number of variable parameters under the modes lower that the maximum. It shows that the identified model allows obtaining the prediction results of the GTE parameters and characteristics through operating modes with a deviation of no more than 1.4% from the experimental data and, therefore, it will allow reduction of terms and an increase in the quality of power unit development.