Vol 21, No 2 (2022)

Full Issue


Justification of geometric parameters of the engine air particle separator

Gishvarov A.S., Rakhimov A.R.


The Engine Air Particle Separator is considered to be the most important element for maintaining the performance of helicopter engines when operating in dusty air conditions. The intensity of erosion of the elements of the gas-air passage of the gas turbine engine depends on many factors: on the hardness and chemical composition of dust particles, on the fractional composition, sand concentration, engine operating condition etc.Therefore, the development of a method for selecting the optimal values of the Engine Air Particle Separator parameters is a complex multi-criteria and multi-factor task. The present document addresses the selection method of optimal values (geometric dimensions) of the Engine Air Particle Separator parameters in aviation gas turbine engines. The methodology includes six main steps. The choice of optimal values of the Engine Air Particle Separator geometrical parameters is accomplished taking into account three partial criteria for the Engine Air Particle Separator efficiency: the degree of air purification, pressure loss and mass. The Engine Air Particle Separator parameters are selected using the Pareto method. An example of choosing the optimal values of the geometric parameters of a cyclone Engine Air Particle Separator is considered.

VESTNIK of Samara University. Aerospace and Mechanical Engineering. 2022;21(2):7-15
pages 7-15 views

3D investigation of heat exchange and hydrodynamics of high pressure turbine nozzle block platforms with different cooling schemes

Gorelov Y.G., Ananyev V.V., Zolotuhina D.A.


Turbine nozzle blocks were tested and, as a result, problems of nozzle block lower platform alligatoring were detected. In the course of the research possible variants of cooling high pressure turbine nozzle block vane platforms were investigated. According to the results of 3D ANSYS CFX calculation the cooling efficiency of high pressure turbine vane platforms with film cooling and convective-film cooling were compared. Research was carried out to eliminate the alligatoring defect of the lower vane platform with convective cooling. Necessary changes in the design were made due to which the cooling air from the secondary combustion chamber area was redistributed over the surface of the turbine nozzle block lower platform. To force the gas turbine engine to  the inlet gas temperature to 1800 К and more, and to increase the cooling air mass flow from the secondary combustion chamber area over the platforms using convective cooling methods not requiring developed ribbing and impingement cooling, areas of the platforms, as well as zones demanding insignificant intensity of cooling are shown.

VESTNIK of Samara University. Aerospace and Mechanical Engineering. 2022;21(2):16-27
pages 16-27 views

Standardization of diagnostic indicators of gearbox teeth wear in aircraft gas-turbine engines

Sunduckov A.Y., Shakhmatov Y.V.


The gearboxes of aircraft gas turbine engines are their most stressed parts. One of the main gearbox defects is the tooth flank wear that causes resonant oscillations in engine structure elements. This defect is generally assessed using vibroacoustic diagnostics methods. It is noted that the currently existing recommendations on setting limit values for diagnostic indicators do not take into account the type of mathematical models that describe their dependence on the defect size. This can result in its uncontrolled development. We have shown that for the case under consideration, four kinds of mathematical models were earlier obtained to describe dependences of diagnostic indicators on the wear value: linear, power, exponential and combined (linear and exponential) models. The linear model is characterized by a constant rate of change in the level of a diagnostic indicator with the growth of wear. For power and exponential models the growth of wear leads to an increase of the rate of change in the diagnostic indicator value. The combined model is characterized by the presence of two zones of change in the diagnostic indicator intensity with the growth of wear: the constant rate zone and the zone of increasing rate. The use of diagnostic indicators with a continuous increase in their intensity depending on the growth of wear will require ensuring constant control of the gearbox vibration state, which is not always feasible. We give recommendations for setting standard values of the diagnostic indicator intensity for the considered models.

VESTNIK of Samara University. Aerospace and Mechanical Engineering. 2022;21(2):28-37
pages 28-37 views

Validation of the “stage – diffuser” system numerical study and its use for design modernization

Cherkasova M.G., Semakina E.Y., Chernikov V.A.


The efficiency of a gas turbine largely depends on the aerodynamics and pressure recovery capacity of the diffuser. For reliable numerical simulation of the flow in the diffuser, the model must be validated on the basis of experimental data on the flow structure. An experimental and numerical study of the “stage – diffuser” system was carried out. The results of this investigation are as follows: the area of applicability of the numerical method for assessing the flow in the “stage – diffuser” system was determined; recommendations for preparing a numerical model and transferring boundary conditions from domain to domain were developed; the importance of profiling the last turbine stage to ensure unseparated flow entry into the diffuser is indicated; the influence of the hub length and the geometry of the struts on the losses in the diffuser and its pressure recovery capacity is determined. It is shown that increasing the hub length to certain limits improves the pressure recovery ratio of the diffuser. The smallest thickness of the struts gives the best results; the tangential and axial slope of the struts does not make a significant contribution in the nominal operating mode of the gas turbine.

VESTNIK of Samara University. Aerospace and Mechanical Engineering. 2022;21(2):38-47
pages 38-47 views


A review of hybrid additive manufacturing of metal parts

Balyakin A.V., Oleynik M.A., Zlobin E.P., Skuratov D.L.


This article provides an overview of the latest developments in the field of hybrid additive manufacturing of metal parts. The concept and various kinds of additive manufacturing are discussed.  Special attention is paid to hybridization of additive technologies and various processes of forming: die forging, deep drawing, and others. The background and significance of the technologies, as well as their applicability in production are presented. The combination of additive manufacturing with forming processes is carried out with a dual purpose: to expand the area of application of additive manufacturing and overcome its limitations associated with low productivity, metallurgical defects, surface roughness and lack of dimensional accuracy; new application of traditional forming processes.

VESTNIK of Samara University. Aerospace and Mechanical Engineering. 2022;21(2):48-64
pages 48-64 views

Experimental and analytical determination of the elastic characteristics of layered woven composites

Komarov V.A., Pavlov A.A., Pavlova S.A.


The challenge of determining nine elastic characteristics of orthotropic woven composites is considered. Using a test example, the influence of transverse elastic characteristics on the results of the stress-strain state analysis of composite structures is assessed. To determine the transverse elastic constants of an orthotropic woven composite, we propose to use a representative volume of the material’s repeated structure. The features of creating a finite element model of a representative volume of a layered woven composite are considered. To determine the elastic properties of an orthotropic woven composite, kinematic boundary conditions of a special type and calculation ratios are proposed that virtually simulate a mechanical experiment with a representative volume of material. The results of comparison of the calculated characteristics and field test data by standard methods are presented, which indicate the possibility of predicting transverse elastic characteristics by computational methods with a sufficiently high accuracy for use in practical tasks.

VESTNIK of Samara University. Aerospace and Mechanical Engineering. 2022;21(2):65-79
pages 65-79 views

Influence of pad geometry and method of oil supply on the thermal state of GTE rotor tilting-pad journal bearing

Parovay E.F.


High heat generation in the hydrodynamic wedge is one of the main factors limiting application of pad journal bearings as bearings for rotors of aircraft gas turbine engines. The goal of the research is to study the influence of the oil supply method on the bearing thermal state and to determine the design factors reducing the bearing temperature. The study was carried out with the use of bearings with diameters of 100…320 mm with different design of the oil supply: through oil dispensing grooves in the pads, through oil nozzles in the inter-pad space, using lead-in chamfers for the pads, with oil bypass channels. The tasks posed were solved by using volumetric geometric models with the tools of computational fluid dynamics in the ANSYS CFX package in which differential equations describing the model are solved by the finite element method. The patterns of temperature and pressure distribution over the surface of the lower, most loaded bearing pad were obtained for various options of oil supply and different geometry of bearing pads; values of the bearing load carrying capacity, maximum pressure in the working gap, the oil mass flow through the elements of the oil supply; dependences of the bearing static performance on the distance between the shaft and nozzles. Oil supply through oil dispensing grooves made in pads is a factor that negatively affects the bearing thermal state, which is associated with so-called “locking” of the working gap. It is shown that implementation of oil supply through the space between the pads is more efficient. The use of a lead-in chamfer with plain inserts simplifies oil supply to the working gap. The design solutions described make it possible to reduce the maximum oil temperature in the bearing by 3…6 degrees Celsius.

VESTNIK of Samara University. Aerospace and Mechanical Engineering. 2022;21(2):80-92
pages 80-92 views

Creation of promising technologies for producing holes in parts of a high-frequency ion engine

Ryazantsev A.Y., Yukhnevich S.S., Shirokozhuhova A.A.


The article considers application areas of various machining methods for perforating holes in parts with unpredictable surface fluctuations. The most effective methods of obtaining holes in parts of a high-frequency ion engine are shown. Studies of perforation technologies using various machining methods have been carried out. Qualitative relations between the geometric dimensions of a spherical billet perforated using a mechanical method, and the quality of the product surface layer are considered. An analysis of modern machining methods is carried out; promising technologies for obtaining holes in parts with a variable profile are presented. The necessity of using high-tech technologies for perforation in high-frequency ion engine parts is justified. The results obtained allow us to significantly expand the production technological capabilities, as well as significantly improve the technical characteristics of special equipment products in mechanical engineering.

VESTNIK of Samara University. Aerospace and Mechanical Engineering. 2022;21(2):93-99
pages 93-99 views

Predicting changes in radial and axial clearances in ball bearings lubricated with low-viscosity liquids

Silayev B.M., Barmanov I.S.


Parts of rolling bearings lubricated with low-viscosity fluids are subject to intense wear of the working surfaces. The bearing life cycle under these conditions depends on the wear rate of the friction surfaces. Therefore, it is important to establish the relationship between the wear rate, the change in the clearances and the duration of work. This paper presents the results of wear tests for rolling ball bearings. After the tests the radial and axial clearances were measured, their changes and the duration of operation were analyzed. Having determined the path of friction, the wear rates of the bearings were calculated based on the values of changes in the radial and axial clearances. The wear rate of the bearing on the axial and radial clearances was plotted against the reduced (equivalent) load. The obtained dependences were approximated with a confidence of at least 98%. The obtained analytical expressions allow us to perform express calculations for changes in the bearing clearances. This will make it possible to forecast the bearing service time, taking into account the wear of the working surfaces under specified conditions, while ensuring correct functioning of the support assembly.

VESTNIK of Samara University. Aerospace and Mechanical Engineering. 2022;21(2):100-108
pages 100-108 views

Influence of surface roughness on the heat transfer coefficient of fluids in an additively manufactured supercharger

Smekalkin A.S., Ivanov A.V.


The supercharger is intended for heating a fluid (gaseous helium or gaseous nitrogen) used for the pressurization of fuel tanks of oxidizer and propellant of a rocket engine. The fluid is heated with the generator gas downstream the turbine. A supercharger with increased channel surface roughness was  made according to an additive technology. High roughness is one of the features of producing parts by selective laser melting. The article presents a method of calculating the heat transfer of generator gas and nitrogen, as well as the results of heat transfer both with and without account of the surface roughness in the channels of the liquid-propellant engine’s additively manufactured supercharger. Firing tests were carried out at the research base of NPO Energomash JSC. The calculated and experimental values of the temperature of the working medium at the outlet of the supercharger are compared.

VESTNIK of Samara University. Aerospace and Mechanical Engineering. 2022;21(2):109-114
pages 109-114 views

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