Vol 20, No 4 (2021)

Full Issue


Special aspects of numerical simulation of a two-stage axial-flow compressor with defective blades

Blinov V.L., Zubkov I.S., Iskortsev E.Y., Belyaev O.V., Plishkin P.I.


The paper presents the results of a stage of development of an analytical model for assessing the impact of various defects on the operation of an axial-flow compressor. Some recommendations on setting the numerical models for carrying out gas dynamic and strength analysis of compressor stages and blades with account for various defects are proposed. Verification was carried out for the models presented: the results are also presented in the paper. On the basis of the verification results some special aspects of CFD-modeling are discussed. The requirements for the defects under investigation are defined. A classification of the defects that can be analyzed with the use of the developed mathematical description of the geometry of airfoils and blades with account of all proposed recommendations for the setting of the numerical model is presented.

VESTNIK of Samara University. Aerospace and Mechanical Engineering. 2021;20(4):7-19
pages 7-19 views

Choice of gas temperature at the turbopump turbine inlet

Ivanov A.V.


The article considers some issues of choosing the gas temperature at the inlet of a liquid rocket engine turbopump turbine. The turbine is one of the key elements of the engine and its operability depends on the gas temperature. In addition, the turbine inlet gas temperature determines its power and main parameters of the engine – chamber pressure and thrust. The higher turbine inlet gas temperature, the higher the chamber pressure and the better engine performance. The permissible temperature of the turbine structure is determined by the required safety margins and durability of the turbine rotor blades. For expendable engines, the safety margin is determined by the material short-term strength at maximum gas temperature. For reusable engines with a long service life, the safety factor is determined by the material long-term strength. The article presents the main factors affecting the choice of the generator gas temperature. It shows that one of the main factors is the non-uniformity of the temperature field at the turbine inlet. The choice of maximum admissible temperature is determined not so much by the engine schematic – with the afterburning of oxidizing or reducing generator gas, but by the strength and durability of the structure with account of the influence of temperature factors.

VESTNIK of Samara University. Aerospace and Mechanical Engineering. 2021;20(4):20-27
pages 20-27 views

The structure of knowledge base to support the development of low-thrust liquid-propellant rocket engines based on computer technologies

Ryzhkov V.V.


Some data on the knowledge base to support the development of low-thrust liquid-propellant rocket engines using computer technologies are presented. The structure of the base is proposed on the basis of characteristic features of engines, including the purpose, fuel components, physical principles of organizing the work process of the engines, etc. The presence of electronic versions of schematic diagrams, configuration and the main achieved characteristics in the database will make it possible to choose effective design solutions at the design stage of new products.  In the future these solutions will lead to the required parameters and characteristics of the low-thrust rocket engines being developed. The description of the engine used in the database allows assessing the capabilities of the engineering solution used in the design, as well as tracing the development trends of a particular direction in rocket propulsion. The peculiarity of the base being created is that, in parallel with the information about low-thrust rocket engines, the data on their components and accessories is accumulating, which can also be used in new developments. Given the growing volume of the knowledge base on low-thrust rocket engines, some forms of communications are presented that make it possible to quickly find the required information, but requires certain ordering of the design data already at the initial stages.

VESTNIK of Samara University. Aerospace and Mechanical Engineering. 2021;20(4):28-39
pages 28-39 views

Specific features of pressure pulsation control in combustion chambers of land based gas turbine units

Skiba D.V., Maksimov D.A., Kashapov R.S., Kharisov T.S.


LLC SPC “Teplofizika”, developing low-emission combustion chambers with premixing of fuel for ground application gas turbine installations, investigates the problems associated with the occurrence of pressure pulsations in the combustion chambers, as well as with the methods of their registration and measurement. To date, there is no unified method for assessing and calculating the amplitude-frequency characteristics of these pulsations and their measurement in general. This article is based on many years of experience in measuring and recording pressure pulsations under the conditions of a test bench and operation. Methods for evaluating and accumulating measurement results are presented, criteria for determining the average frequency and amplitude of oscillations are developed, reproducible in the course of experiments and during full-scale measurements. To detect vibrating combustion, an additional criterion of coherence of vibrations is also used with the aid of the entropy coefficient. As a result of the computational and experimental study, we find that the pulsation pressure in the volume of the combustion chamber does not allow the use of probes for measuring pressure pulsations in the air volume of the combustion chamber to reliably prevent the occurrence of vibrating combustion during its operation.

VESTNIK of Samara University. Aerospace and Mechanical Engineering. 2021;20(4):40-51
pages 40-51 views

Parametric study of the influence of location and extension height of the rod interceptor on jet engine nozzle characteristics

Tishchenko K.O., Brykov N.A., Belyaeva A.S.


Modern aircraft need increased maneuverability to maintain a competitive position. One way to improve this characteristic is to use methods to adjust the thrust vectors of a jet engine nozzle. One method of controlling nozzle thrust is the use of nozzle interceptors – devices of various shapes that extend into the nozzle channel and cause an uneven distribution of pressure along the walls of the channel. The extension of the rod interceptor near the critical section of the nozzle creates a greater lateral force than the extension of the rod near the exit section. The dependence of the lateral force on the extension height is nonlinear. The article presents a description of a nozzle interceptor of a cylindrical shape extended from the channel wall. Numerical simulation of gas flow in the nozzle with a cylindrical interceptor was carried out. The patterns of gas flow in the channel and in the environment outside the nozzle are presented. The plots of the lateral and axial components of the thrust force against the interceptor rod length are also presented for both cases of the rod location. Rod interceptors can be used in combination with other correcting devices. 

VESTNIK of Samara University. Aerospace and Mechanical Engineering. 2021;20(4):52-58
pages 52-58 views

Selection of the optimum configuration and calculation studies of the parameters of a cryogenic propulsion system for an unmanned aerial vehicle

Tremkina O.V., Uglanov D.A., Urlapkin V.V., Korneev S.S., Komisar Y.V.


A computational study of the parameters of a propulsion system of an unmanned aerial vehicle operating on a cryogenic working medium has been carried out. Liquid nitrogen was selected as the cryogenic working fluid. Two alternative configurations of a cryogenic propulsion system for an unmanned aerial vehicle are presented. The first one is a scheme of an air-heated cryogenic propulsion system of an unmanned aerial vehicle in which air acts as the heat source at an ambient temperature at an altitude of 2000 m. The second one is a scheme wherein the working fluid is heated due to solar energy, in this case solar energy acts as the source of heat. A computational study of a cryogenic propulsion system operating on the open Rankine cycle was carried out, as well as computational studies of possible cryogenic propulsion system configurations. As a result of the studies a comparative analysis of the data obtained was made and a suitable cryogenic propulsion system configuration for an unmanned aerial vehicle with the required parameters was selected.

VESTNIK of Samara University. Aerospace and Mechanical Engineering. 2021;20(4):59-68
pages 59-68 views


Determining static stiffness of damper elastic rings

Diligensky D.S., Novikov D.K., Boyarov K.V.


The article describes a method for experimental evaluation of the stiffness of an elastic damper ring.   A thin-walled low-stiffness ring with uniformly distributed smooth protrusions on the inner and outer surfaces acts as a damper ring. Despite the widespread use of such a design in domestic and foreign mechanical engineering, control of the characteristics of this element and, accordingly, of the support as a whole remains quite difficult. A numerical model was developed, the reliability of which is confirmed by analytical calculations. To check the data obtained by numerical calculations, a special device was designed, which was installed on the “galdabini” tensile testing machine, where a series of measurements was carried out. Analysis of the data obtained showed a significant difference between the numerical, analytical and experimental data, which can be explained by the discrepancy between the equipment used and the boundary conditions of the theoretical model. The parameters of the device were selected in such a way that its rigidity was much higher than the rigidity of the elastic ring under study. The paper describes the improvement of both the design of the device and the method for determining the stiffness of the elastic ring of the damper using the specified measuring equipment. After making corrections, the obtained data on the scatter of the stiffness of the elastic ring are in good agreement with the analytical and numerical dependence, which makes it possible to use the data of the latter to refine the analytical methods in the future

VESTNIK of Samara University. Aerospace and Mechanical Engineering. 2021;20(4):69-78
pages 69-78 views

Increasing the efficiency of low-temperature power plants by selecting the optimal working fluid of the auxiliary circuit

Eliseev I.A., Tochenov V.V., Panshin R.A.


The article discusses one of the ways to improve the efficiency of low-temperature power plants.  Selection of the working substance for the auxiliary low-temperature power circuit is a relevant option for increasing the power. The low temperature potential of cryogenic substances is used to improve the efficiency of energy systems. Auxiliary power plants operating according to the Rankine cycle and the Brayton cycle were used in the work since these cycles are most efficient for the operation of auxiliary low-temperature power plants. The following low-temperature cryogenic substances were chosen for the power plant operating according to the Rankine cycle: argon, difluorochloromethane, trifluoromethane, tetrafluoromethane, ethylene, ethane. For the power plant operating according to the Brayton cycle we chose ethylene, trifluorochloromethane, tetrafluoromethane. According to the results of calculations, as well as according to the results of analyzing the dependence of power on the degree of increasing the pressure, we suggest several cryogenic substances that show the best performance among the considered working fluids.

VESTNIK of Samara University. Aerospace and Mechanical Engineering. 2021;20(4):79-88
pages 79-88 views

Research on end mill vibration in machining of VT9 titanium alloy

Sazonov M.B., Zhidyaev A.N.


The reason for the failure of carbide end mills is the chipping of the cutting edges at the transition from the radius edges to the helix edges on the cylindrical part of the cutter. One of the reasons for the chipping of the cutting edges are the vibrations of the end mills which arise due to the intermittent cutting process and the variability of forces acting on the end mill. The principle of operation of a vibration measuring device is considered which allows vibration measurements to be carried out when milling with an end mill. The main measuring elements of the device are two eddy current sensors that allow measuring the vibration displacement of the milling cutter in two directions – perpendicular and parallel to the movement of the longitudinal feed. The device has a compensation sensor that takes into account the influence of related factors, and a sensor for fixing the instantaneous rotation speed of the machine spindle. The milling cutter itself, fixed in a collet chuck, was used as an elastic element of the oscillating system. The data of measuring the amplitude of vibrations during milling of titanium alloy VT9 with a four-tooth and six-tooth end mill are presented. The study of vibrations of end mills included two stages. At the first stage, the influence of milling parameters and modes, as well as milling schemes (up and down milling) on the frequency and amplitude was investigated. At the second stage, measures were worked out to reduce the intensity of vibrations and increase the reliability and durability of the milling cutters. The research results showed lower amplitude values when working with a six-tooth cutter.

VESTNIK of Samara University. Aerospace and Mechanical Engineering. 2021;20(4):89-99
pages 89-99 views

Scratch testing of electrolytic nickel coatings on a carbon fiber reinforced plastic substrate

Salakhova R.K., Kirilin S.G., Tikhoobrazov A.B., Smirnova T.B.


A method for quantitative assessment of the strength of nickel coatings’ adhesion to CFRP KMU-11-M2.200 by the sclerometry method with the use of a laboratory scratch tester is proposed. The method has expanded capabilities due to the operation according to two loading programs and an additional technique for recording the moment of destruction of the coating by changing the scratch resistance force. The appearance and schematic diagram of the non-standard ST-01 scratch tester, developed at the STCU VIAM, are presented. Scratch testing of nickel coatings obtained by the traditional electrochemical method in a bath and by the method of local brushing was carried out, with two methods of pre-treatment of the carbon fiber surface before nickel plating being considered (sandblasting and nitric acid etching). The surface morphology was investigated by optical microscopy and the thickness of nickel coatings deposited in the bath and by brushing was determined. By combining the obtained scratches with the plots of the indenter load and the resistance force against the indenter displacement, the critical load is determined at which continuous destruction of the coating with delamination is recorded. Based on the formulas of P. Benjamin and K. Weaver, the adhesion strength of nickel coatings was calculated and it was shown that the adhesion strength of nickel coatings deposited in a bath is 1.6 times higher than that of coatings obtained by brushing. The results of scratch testing are presented, and the nature of the destruction of nickel coatings at an indenter position of more than 25 mm is described.

VESTNIK of Samara University. Aerospace and Mechanical Engineering. 2021;20(4):100-114
pages 100-114 views

This website uses cookies

You consent to our cookies if you continue to use our website.

About Cookies