СНИЖЕНИЕ ВИБРОНАПРЯЖЕННОСТИ ПОПАРНО БАНДАЖИРОВАННЫХ РАБОЧИХ ЛОПАТОК ТУРБИНЫ

To reduce the vibration stresses arising in the working blades of turbines during resonant excitations caused by the frequency of passage of the blades of the nozzle apparatus, it is necessary to control the level of aerodynamic exciting forces. One of the ways to reduce dynamic stresses in rotor blades under operating conditions close to resonant, in addition to structural damping, maybe to reduce external exciting forces. To weaken the intensity of the exciting forces, it is possible to use a nozzle apparatus with multi-step gratings, as well as with non-radially mounted blades of the nozzle apparatus.This article presents the results of numerical calculations of exciting aerodynamic forces, as well as the results of experimental measurements of stresses arising in pairwise bandaged working blades with a frequency zCA ⋅ fn, where fn – is the rotor speed, zCA – is the number of nozzle blades. The object of research was the high-pressure turbine stage of a gas turbine engine. Two variants of a turbine stage were investigated: with the initial geometry of the nozzle apparatus having the same geometric neck area in each interscapular channel and with the geometry of the nozzle apparatus obtained by alternating two types of sectors with a reduced and initial throat area.The presented results are obtained on the basis of numerical simulation of a viscous unsteady gas flow in a transonic turbine stage using the SUnFlow home code, which implements a numerical solution of the Reynolds-averaged Navier-Stokes equations. Discontinuity of a torrent running on rotor blades is aggravated with heat drops between an ardent flow core and cold jets from film cooling of a blade and escapes on clock surfaces. Therefore, at simulation have been allowed all blowngs cooling air and drain on junctions of shelves the impeller.As a result of the replacement of the nozzle apparatus with a constant passage area by a nozzle apparatus with a variable area, a decrease in aerodynamic driving force by 12.5 % was obtained. The experimentally measured stresses arising in a pairwise bandaged blade under the action of this force decreased on average by 26 %.

Study of physical and mechanical properties of working blades material effect of the noise from the mine axial fan

Introduction. The high level of sound pressure created by an industrial axial fan negatively affects the performance of people, leads to a decrease in attentiveness, and provokes production errors. The desire to use small-sized and high-performance turbomachines leads to the need to find ways to create ventilation units with a reduced noise level. Research methodology. One promising way to influence the noise characteristics of axial machines is to prevent resonant vibrations of the working blades due to the manufacture of a material with calculated physical and mechanical characteristics. To date, a mathematical model of the blade as an elastic element has been constructed, which allows us to determine the frequency of its own vibrations. Comparison of this ISSN 0536-1028 «Известия вузов. Горный журнал», № 5, 2020 107 frequency with the frequency of external influences will allow us to conclude about the probability of entering the blade into resonance with external influences. Results. In order to test the theoretical positions, an experiment was performed in which the sound pressure created by geometrically identical impellers was measured: aluminum, which is included in the fan delivery, and composite. Conclusions. It was found that equipping the fan with a wheel with composite blades can significantly reduce the sound level, which confirms the prospects for creating low-noise axial fans by making working blades of a material with calculated physical and mechanical characteristics.

MATERIALS SCIENCE RESEARCH DEFECT OCCURRENCE AND RUPTURE OF THE GAS PUMPING UNIT AXIAL COMPRESSOR BLADE

The article discusses the results of the study of the causes of destruction of the axial compressor blade and the causes of the defect of the working blade 10 stage GTU GPA type GTK-10-4 station No. 18 of the compressor station “Dzhangala”. The blade is made of X20Cr13 steel (AISI 420). The blades have an operating time of 23 284 hours after the last repair. Chemical analysis, fractographic analysis, and hardness measurements were performed. The probable cause of defect formation and destruction of the blade is established. The measured hardness values comply with the standard. А study of the chemical composition of metal blades is not revealed a deviation in the content of the main alloying elements. The results of fractographic analysis showed that the destruction caused the presence of a subsurface defect. The defect is an oxidizing shell of about 9×4 mm in size with propagation in operation to the outer surface. In operation, as a result of corrosion, static and dynamic stresses, a crack was formed in the area of the source with exit to the surface along the input edge of the blade. Non-destructive testing was performed on the remaining blades. No defects detected. On the basis of which it was decided to continue the operation of the working blades of the GTK-10-4 turbine, subject to periodic monitoring.

BASIC APPROACHES TO THE CHOICE OF MATERIAL FOR WORKING BLADES OF THE LAST STAGES OF THE LPC OF POWERFUL STEAM TURBINES

The paper outlines the need for a comprehensive analysis and selection of steels for the working blades of the last stages of low pressure cylinders (LPC) of high-power steam turbines. The authors reviewed the criteria and exist-ing technical requirements for the materials of the working blades. The analysis of various grades of steels for low-pressure cylinder blades was carried out taking into account the experience of their production at JSC “Turboatom”. The proposals on the use of materials of working blades with a large length of the active part are given, as well as ways for further research are outlined.

ХОЗЯЙСТВЕННЫЙ КОМПЛЕКС СТОЯНКИ ПАВЛОВО 1 В ИРКУТСКОЙ ОБЛАСТИ

Trasological studies of the Early Holocene blade industry were made for the first time in the archeology of the Lower Vitim and the Baikal region. All working blades of the tools were taken into account and data on economic activities in the site lot were obtained. Based on the research results, Pavlovo 1 site can be defined as a short-term hunting site for processing hunting products. The data of the traceological analysis showed the need for such studies, since the data of the technical-typological study are not sufficient to obtain information on the economic orientation of the parking lot.

ДЕМПФИРОВАНИЕ КОЛЕБАНИЙ ОХЛАЖДАЕМЫХ ПОПАРНО БАНДАЖИРОВАННЫХ РАБОЧИХ ЛОПАТОК ТУРБИН

The cooled turbine blades are the parts that determine the reliability and service life of a gas turbine engine. As is known, most cases of engine failure are related to the destruction of turbine blades. Turbine blades during operation experience high thermal stresses, the stresses from centrifugal and gas forces, as well as dynamic stresses. This paper presents methods for ensuring an acceptable level of dynamic stresses in turbine blades. One of the most effective methods is considered in more detail - pairwise shrouded cooled turbine blades. The effectiveness of the damping of such working blades depends on the guaranteed contact of the contact surfaces of the flanges of the shanks and banding shelves and the optimality of the shroud connection. As the object of the study, we chose pairwise shrouded turbine blades from the engine, on which there were several cases of destruction of the turbine blades. To assess the optimality of the bandage connection of the working blades under study, a scheme has been developed for calculating the force acting on the contact surfaces of the banding shelves. According to the developed scheme, calculations were made of the forces acting on the contact surfaces of the retaining shelves, both of the investigated working blades, and similarly pairwise shrouded cooled turbine blades, developed by SE «Ivchenko-Progress». After calculating the force acting on the contact surface of the retaining shelf, the ratio of the received force to the parameters of the feather profile, such as chord and CMAX, is calculated. According to the data obtained, a graph of the dependence of the voltage in the blade on the relative force acting on the contact surface of the retaining shelf was plotted. The analysis of the obtained graph made it possible to conclude that there is an optimal force at which dynamic stresses will be acceptable. However, since a small sample of pairwise shrouded cooled turbine blades is presented, it is necessary to continue the work on determining the criteria for optimality of the shroud linkage and on clarifying the resulting relationship.