Research in the field of active fluid-film bearing has been recently getting more and more attention, integration of control systems becoming one of the most promising means of enhancement of rotor-bearing nodes' characteristics. It has been determined that the vast majority of papers published on active fluid-film bearing only consider radial bearings, and very few focus on thrust bearings. This lack of attention along with the obvious necessity to fill the said gap has triggered the present research. In cases of rotor machines that experience extensive axial loading due to various reasons, e.g. various turbine engines (aero and spacecraft) and hydraulic pumps (crude oil extraction facilities), such research could prove the feasibility of application of a control system to significantly increase the performance of the whole machine. Moreover, extensive wear during start up and shut down could be eliminated by means of rotor position control, thus life time of a rotor-bearing system could be significantly increased. The present paper features a complex mathematical model of an active thrust fluid-film bearing with a central feeding orifice, a developed test rig designed to verify the presented mathematical model allowing a series of numerical tests to be carried out. Numerical studies focus on the hypothesis of a possibility to use active control in thrust bearings to decrease power loss due to friction and extensive axial vibrations by means of identification of an energy efficient area of axial gaps based on the lubrication regime and its maintenance by means of application of controlled lubrication principles.

Failure diagnostics and general decrease of accident rate at power plants is a major task of energy generation industry, and solution of it provides reliable energy supply country wide and technological progress in mechanical engineering. Along with some other crucial means, the task could be solved by means of teaching the maintenance staff based on accidents that have already occurred. That is no secret that everywhere in the world due to indecision or misinterpretation a huge number of accidents have happened merely because the personnel were not aware of similar cases at other power plants. Nevertheless with the development of computational technologies and mathematical algorithms the role of personnel in some cases has been reduced to observation and action in critical situation, while the rest is performed by machines: various types of diagnostics and prediction of failure systems based on artificial neural networks are widely applied and developed. However, in order to train these systems, it is absolutely required to know the reasons that could lead to and consequences that could follow some deterioration in turbo generator sets performance. The aim of the present paper is to give statistical analysis of turbo generator sets failure reasons based on open source data presented by Russian and foreign researchers and analysts in the field. The statistical data could be used to perform classification and ranking of failure reasons in terms of frequency of occurrence, possibility to identify or detect, etc. and the paper also gives brief listing of possible ways of detection or identification of failure modes and possible consequences for the main units of a turbo generator.

The following parameters have the most influence on the dynamics of a high-speed turbomachine's rotor system: mass and stiffness distribution of a rotor; damping properties of the materials of rotor's elements; location of bearings, sealings, and dampers; type, design, and operational conditions of bearings, sealings, and dampers; mass and inertia characteristics of machine's housing; and operational conditions of a turbomachine itself. It should be noted that the presence of fluid film bearing complicates the dynamic analysis. It is thus a quite urgent task to search for some rational parameters when a rotor system is under design and preliminary calculation, which in many cases leads to the problems of an optimal parametric design. One of the main yet controversial problems of parametric design in the field of rotor system dynamics is the determination of quality indicators for a particular case of a rotor system. The present paper proposed a criterion based on the efficiency of rotor system's input energy. The analysis of a number of parameters', e.g., values of constant external forces (rotor's mass), varying external forces (imbalance), and types of bearings, influence on this criterion has also been carried out.

Diagnostics of rotating machines is taking a new step forward with the development of intellectual technologies based on predictive and machine learning tools. Despite having a range of advantages compared to humans in terms of big data processing powers, correlation and various feature extraction possibilities, and swiftness of operation, such systems are limited by measurement system elements in terms of their parameters: sensors and ADCs with their sensitivity properties and accuracy restrictions, microprocessors with limitation of processing powers, etc. Experimental data is used to recreate experimental environment in simulation of induced unbalance. The imitation model is based on rotor dynamics equations of rotor motion, Reynolds equation to estimate reaction forces of a fluid-film bearing and takes into account sensor parameters and position, gear coupling effect and other measurement system elements parameters. The results show that under certain conditions it becomes impossible to successfully track unbalance which in real conditions could lead to malfunction or failure of a rotor machine.

Abstract. The present paper considers simulation of a rotor's dynamics behaviour on thrust foil gas dynamic bearings based on simultaneous solution of gas dynamics differential equations, equations of theory of elasticity, motion equations and some additional equations. A double-mass dynamic system was considered during the rotor's motion simulation which allows not only evaluation of rotor's dynamic behaviour, but also to evaluate the influence of operational and load parameters on the dynamics of the rotor-bearing system.