Vol 14, No 3-2 (2015): Special Issue

  • Year: 2015
  • Articles: 26
  • URL: https://journals.ssau.ru/vestnik/issue/view/132
  • Description: посвящённый 85-летию Центрального института авиационного моторостроения имени П.И. Баранова

Full Issue

Optimization of the workflow of multistage axial turbines with platforms
Matveev V.N., Baturin O.V., Popov G.M., Goryachkin E.S.
Abstract

The turbine workflow is described by a large number of variables that often have contradictory impact on the turbine operating parameters. Hand-operated variation of these variables is a difficult time-consuming task. Application of mathematic optimization techniques could provide a solution of the problem. The paper outlines the basic principles of the method of mathematical optimization of an axial turbine based on the joint use of the NUMECA computational fluid dynamics software and the IOSO program optimizer. The procedure developed was implemented for a four-stage turbine developed and tested by NASA. Design models including one, two, three and four stages have been developed for the turbine under consideration. The results of calculations performed with their help showed good agreement with the experimental results. The settings of the numerical model that provide good agreement of design and experimental data but do not require large computational resource have been chosen according to the results of the research conducted. Low computational cost is very important because it allows significant reduction of the time spent to obtain the optimal solution with repeated reference to the design model. Automatic search of the turbine blade configuration allowing a 0.7 % increase of the turbine efficiency with constant mass flow and rate of expansion of gas (accuracy 0.5 %) was carried out with the help of the model created. 

VESTNIK of Samara University. Aerospace and Mechanical Engineering. 2015;14(3-2):271-283
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The use of mathematical optimization means to increase the efficiency of a seven-stage axial flow compressor
Baturin O.V., Popov G.M., Gorachkin E.S., Novikova Y.D.
Abstract

The paper describes a method of computer-aided redesign of axial flow compressor blades. The method is based on the combined use of the NUMECA computational fluid dynamics software package and the IOSO program optimizer. The basic idea of the method is that, at each iteration, the optimizer generates a variety of parameters that determine the compressor’s geometry. Finite-element models of a compressor are created on its basis in the NUMECA AutoGrid program. The parameters of operation in one or more points on the characteristic of the compressor are calculated in the NUMECA Fine / Turbo program with their help. The calculation results are transferred to the optimizer, where the obtained values are compared with the specified limits. Then a new set of input data is formed. The cycle is repeated until the required criteria of the compressor operation are achieved. The developed method was tested on a seven-stage high-pressure compressor of the NK36-ST engine. The article describes the constructed numerical model and the results of the verification by comparing the calculated data with the experimental data. The model developed makes it possible to obtain results close to the experimental ones and does not require large computational resource. The optimization of the compressor was carried out in two versions using the developed model: 1) increasing the efficiency of the operation mode with the rotation frequency of the rotor of 100% of the maximum by changing the blade setting of the first three stages, 2) improving the efficiency of the two operation modes with the the rotation frequency of the rotor of 80 and 100% of the maximum due to changing the blade setting. It is shown that in the first case the compressor efficiency can be increased by 0.3%. In the second case, the efficiency can be increased by 1.2% at the rotation speed of 80% and 0.5% at the speed of 100% just by changing the blade setting.

VESTNIK of Samara University. Aerospace and Mechanical Engineering. 2015;14(3-2):284-295
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Application of stereolithography prototypes for gas dynamic tests
Matveev V.N., Shabliy L.S., Krivcov A.V.
Abstract

Planning any pilot study brings up the question of producing test specimens. These are quite often rather complex, consisting of several individual parts put together. Test specimens are very expensive and take long time to produce using traditional technologies of production because of high accuracy required of them and absence of quantity production. Dynamically developing additive technologies (rapid prototyping) make it possible to produce plastic and metal parts of any form using a uniform technology. Therein the complexity of the part shape practically does not increase the manufacturing complexity and the need for equipment is absent or minimal. Laser stereolithography (SLA – Stereolithography Laser Additive) is one of the earliest and most precise technologies of 3D-printing. The paper presents the experience of using a prototyping machine on the basis of laser stereolithography for the production of experimental specimens for gas-dynamic investigations. On the basis of synthesis of this experience, basic requirements for similar experimental specimens are formulated: durability, rigidity and hardness, impermeability for gas or liquid, resistance to working fluid diffusion, resistance to chemically aggressive fluids (including fuels, oils). Comparison of different technologies of prototyping shows that stereolithographic models meet all listed requirements better than others. 

VESTNIK of Samara University. Aerospace and Mechanical Engineering. 2015;14(3-2):296-304
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Methods of modeling the work process of hydrogen screw-centrifugal pumps using ANSYS CFD
Sulinov A.V., Shabliy L.S., Zubanov V.M.
Abstract

Basic methods of modeling hydrodynamic processes in hydrogen screw-centrifugal pumps using the ANSYS CFD software are described in the paper, including those that take into account variable density of the fluid. Compressibility of liquid hydrogen caused by temperature and pressure changes, despite the alowances of average density, requires taking into account variable density for improved accuracy of modeling the workflow of hydrogen pumps. A technique of CFD-modeling of hydrogen pumps using special software tools to build the geometry and grid models of interblade channels is presented. Three methods for modeling variable-density fluid flows in ANSYS CFD are proposed. Regression models of the second and fourth orders have been obtained in the pressure range from 0.09 to 30 MPa and in the temperature range from 18 to 34 K to implement the method of setting variable density of liquid hydrogen in the form of functional relation.

VESTNIK of Samara University. Aerospace and Mechanical Engineering. 2015;14(3-2):305-315
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Procedure of validated CFD-modeling of a two-stage screw-centrifugal pump
Zubanov V.M., Shabliy L.S., Krivtsov A.V., Ivanov A.I., Kositsin I.P., Baturin N.V.
Abstract

The article presents a CFD-modeling technique of the kerosene pump work flow. Various methods of improving CFD models have been investigated in the course of work to improve the reliability of simulation results: the selection of the type of boundary conditions, the extension of inlet and outlet pump connections, the estimation of the influence of the grid size and turbulence models. The advantage of boundary conditions of the «Opening» type with the «Opening Pressure» subtype is revealed. Rational lengths of additional pipes for correct modeling are determined:  ½ of the inlet diameter size at the inlet, 4 diameters of the outlet diameter at the outlet for rated operating conditions and 7 diameters for all other conditions. The best combination of turbulence model and mesh sizing have been identified: it is better to use the k-omega turbulence model for a fine grid with the size of the first element equal to 1 micron and the k-epsilon turbulence model for coarser grids. The convergence of solutions is evaluated by the changes of integral parameters of the pump from iteration to iteration. The amplitude of efficiency fluctuations in the process of calculation amounted to 1 % even in the case of the most accurate model. The model reliability is assessed by comparing the design characteristics obtained and the experimental data. The radial load on the impeller bearing is estimated by using the verified CFD model, which also showed qualitative agreement of the calculated and experimental data. Thus, the proposed modeling technique makes it possible to create adequate CFD pump models with the lowest computational costs. CFD-models developed according to the technique can be used for optimization studies of multistage screw centrifugal pumps. 

VESTNIK of Samara University. Aerospace and Mechanical Engineering. 2015;14(3-2):316-326
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Calculation of the damping coefficient of flexible rings with working fluid
Diligensky D.S., Novikov D.K.
Abstract

The paper presents the results of patent search on the subject of squeeze film dampers and a survey of scientific papers on the same subject. The existing classification of squeeze film dampers has been complemented. The analysis carried out shows an increase in the amount of studies associated with damping and, in particular, squeeze film dampers with elastic rings. The paper introduces a procedure of calculating the parameters of a squeeze film damper with elastic rings. Comparative analysis of the results of calculation based on the previously known analytical method and the results obtained in a mathematical experiment has been carried out. Numerical calculation is carried out in the FLUENT software environment. Comparative analysis is made for dynamic models of two path types. Data on a complex pathmodel formed by an elastic ring with metering grooves are presented. The motion prescribed in the model simulates the behavior of a rotor with predetermined disbalance. 

VESTNIK of Samara University. Aerospace and Mechanical Engineering. 2015;14(3-2):327-335
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The influence of residual technological stress and service heat loads on the strength of railway wheels
Kerentcev D.E., Ponomarev J.K.
Abstract

The article deals with the existing approaches to assessing the strength of railway wheels and the problems associated with forecasting actual spots of fatigue crack origination in operation. Solid-rolled railway wheels with a flat cone disk of standard design that have become a frequent practice in the Russian railway system are taken as an example. Calculations of the safety factor of fatigue resistance according to domestic and foreign standards have been carried out. The authors propose a procedure for assessing the wheel fatigue resistance to solve the above problems, taking into account the impact of residual technological stresses caused by heat treatment in the manufacturing process, followed by the repair of the rim, and service heat loads associated with the heating of the rim during braking, when the wheel interacts with blocks. Quantitative assessment of the impact of residual technological stresses and service heat loads on the strength of the wheels is presented. In conclusion the results of testing the computational methods described are presented, wheels of low-stress design with improved performance characteristics developed by the JSC «Vyksa Steel Works» taken as an example.

VESTNIK of Samara University. Aerospace and Mechanical Engineering. 2015;14(3-2):336-344
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Improving the reliability of radial face seals of aircraft engine rotor supports
Falaleev S.V., Bondarchuk P.V., Ibatullin I.D., Badykov R.R.
Abstract

The article presents an advanced radial face contact seal with increased operational life. High efficiency of the radial mechanical seal is ensured by the joint application of the hydrostatic and hydrodynamic lubrication principles. The hydrodynamic effect is achieved by applying the structure of fine grooves on the rotor hub. The dependence of the flow force value in the slot for a fixed-size gap on the rotor speed is presented. A prototype has been made and tested on a dynamic test bed intended for the realization of operating conditions of support seals making up a part of an aircraft engine. The results of theoretical and experimental studies are presented. Ways of improving the seal reliability due to improving the surface mechanical properties are proposed. A pattern of the development of a functional failure of the seal assembly is presented. The most adverse operating conditions and the main reasons of increased wear of the sealing surfaces are indicated.  Methods of achieving high anti-friction characteristics of contact surfaces by applying nanostructured nonporous chrome-diamond coatings are proposed. Issues concerning the creation of advanced coatings with a positive gradient of depth mechanical properties are discussed. Anti-friction, anti-seize silver-diamond coatings and the use of diffusion molecular reinforcement technology are at the basis of the production of advanced coatings. The paper indicates the importance of anti-friction and extreme-pressure additives contained in the oil.

VESTNIK of Samara University. Aerospace and Mechanical Engineering. 2015;14(3-2):345-353
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Research of repeatability of characteristics of multilayered corrugated dampers of aircraft and rocket engines using the Monte-Carlo method
Ponomaryov Y.K.
Abstract

The purpose of the work is to analyze the repeatability of elastic damping properties of multilayered corrugated supports of aircraft and rocket engines in the conditions of out-of-toleranceproduction of component parts in mass production. The research is carried out by the calculation Monte-Carlo method with the use of experimentally confirmed laws of distribution of tolerances on the production of parts constituting the structure of a support. A mathematical model of virtual mass production of supports with multilayered corrugated dampers, a mathematical model of uniaxial static loading of a support, and, on their basis, a model of elastic hysteresis characteristics spread have been developed. Fields of dispersion of characteristics of supports have been investigated for different parameters of accuracy of production of the parts influencing the above characteristics. It has been found that statistical laws of distribution of elastic friction characteristics of multilayered dampers in supports are not subject to the normal law. The most probable values of these characteristics are 20-30% less than the arithmetic mean values calculated for the whole amount of sampling. The calculations showed that in common production practice of combination of tolerances on the production of damper component parts in mass production the variation of their characteristics is not unconsiderable, which results in the need of selection of parts with the required characteristics.

VESTNIK of Samara University. Aerospace and Mechanical Engineering. 2015;14(3-2):354-364
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Research of serviceability of pulsed face seals with pumpback structures
Vinogradov A.S., Badykov R.R., Anokhin D.V.
Abstract

The article discusses characteristics of pulsed face seals, analyzes their work process, and investigates the parameters of seal working efficiency. The experience of investigating seals by leading companies and institutions is presented. Experimental studies on the measurement of water leaks and the frictional torque at variouspressure differentials, rotor speed and spring rates have been conducted. Computational research for the case of air used as the seal working fluid has also been carried out. The dependences of the frictional moment on the rotor speed for seals with different mutual arrangement of pumpback structures have been compared on the basis of the experimental data provided by Stuttgart university. The change of pressure in a pumpback structure is analyzed for the following cases: remote structures, coincidence of structures, proximity of structures. A series of tests has been carried out to estimate the reliability of a pulsed seal. The test results are used for the investigation of experimental frictional torque dependences at different rotation speeds, pressure differentials and spring rates. It has been established that the optimum value of the spring rate is a prerequisite for ensuring the required sealing characteristics.

VESTNIK of Samara University. Aerospace and Mechanical Engineering. 2015;14(3-2):365-374
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Topical issues of gas turbine engine friction unit reliability
Parovay Y.F., Ibatullin I.D.
Abstract

Operation of bearings and seals of gas turbine engines (GTE) is associated with adverse wear effects of friction parts. Boundary friction occuring in startup - shutdown and extreme engine operating modes is characterized by high values of the friction ratio and damage of friction surfaces in the contact zone. This results in damage accumulation, wear and changes in the geometry of the friction surfaces, which leads to degraded performance properties of the product and functional failure. In this case the requirements for fixed geometry in turbomachinery bearings and seals are very strong, since any undesirable change in the shape or size of the working gap leads to a decrease in unit efficiency and engine efficiency as a whole. In addition to the boundary friction regime, the efficiency of bearing and sealing units is decreased due to power friction losses. These losses are always present in friction units, but they can have a significant effect on the unit performance in off-optimum operation (including the turbulent flow regime in the working gap and the wrong choice of lubricant). Some of these problems are solved constructively by changes in the shape of working surfaces, use of special materials and advanced coatings, as well as timely control of the lubricant purity.

VESTNIK of Samara University. Aerospace and Mechanical Engineering. 2015;14(3-2):375-383
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Formation of a model of rheological properties of hard-to-machine materials in the process of intensive cutting force deflection
Khaimovich A.I., Balaykin A.V., Galkina N.V.
Abstract

Improving the efficiency of high-speed machining (HSM) requires in-depth study of the physical phenomena accompanying the cutting process. The main difference between HSM and traditional machining in terms of physics is the prevalence of swift dynamic processes both in the cutting zone and in the “machine - fixture - tool – product” system, as well as marked nonlinearity of the laws of development of these processes. In this regard, the study of physical phenomena accompanying the process of HSM, and the establishment of their relationship with the stability of the cutting process and the quality of the machined surface is an urgent task. This article describes a procedure of determining the parameters of the rheological properties of the titanium alloy BT6 material used in aircraft engine construction, in face milling. The calculations were performed in the CAE system Deform using a FEM-model.

VESTNIK of Samara University. Aerospace and Mechanical Engineering. 2015;14(3-2):384-390
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Application of numerical simulation systems for the research of the blade casting process in blank production
Smelov V.G., Vdovin R.A., Agapovichev A.V.
Abstract

The article focuses on the analysis of the results of computer simulation of the process of casting the turbine blade 24.400.538-1, including prediction of occurrence of casting defects. Engineering calculations have been carried out to model the stress-strain state of the casting during solidification and after the knockout of the casting from the mold. The internal structure of the casting was analyzed for the presence of microporosity. The analysis of the results of modeling the process of grain formation in the casting made it possible to predict the size and direction of grain growth in the casting during its crystallization. Thus, on the basis of in-depth research of the group technology of a complex representative of the most loaded turbine blade and the one most difficult to produce local places of occurrence of casting defects were identified and predicted taking into account the obtained results of simulating the casting process. This made it possible to reduce the amount of defects at the stage of actual production by 8% on the average.

VESTNIK of Samara University. Aerospace and Mechanical Engineering. 2015;14(3-2):391-399
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Experimental research of the surface layer quality and cutting forces in flat grinding of the BT6 titanium alloy
Fedorov D.G., Skuratov D.L.
Abstract

A set of mathematical models, finite-element models and empirical dependences is being developed. All of them require practical testing. The article presents the results of experimental research of the quality and characteristics of grinding specimens made of the BT6 titanium alloy widely used in aerospace industry.  Machining was conducted on a modern surface grinding machine, model 3D711VF11 by a ceramically bonded silicon carbide disk. The operation components of the cutting force, surface roughness (before and after machining of the specimens), as well as residual stresses were measured in the course of operation. All measurements were performed with the same specimens that were sequentially machined with the measurement of the earlier described parameters. In view of this, it is possible to trace all the transformations that take place inside the specimens. A force gage made jointly with the Department of Mechanical Engineering of SamGTU (Samara State Technical University) was used as a force-measuring system. The results of the research can be used to verify the adequacy of the mathematical models created and provide an insight into some processes occuring in surface grinding of flat titanium alloy blanks.

VESTNIK of Samara University. Aerospace and Mechanical Engineering. 2015;14(3-2):400-408
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Influence of tool deterioration on the density of heat flux distribution in the cutting area in end milling of OT4 titanium alloy
Evdokimov D.V., Skuratov D.L.
Abstract

The influence of end mill teeth flank wear on the density of heat fluxes taking place in the cutting area is discussed in the paper. The following densities of heat fluxes are dealt with: the density of heat flux which occurs as a result of plastic deformation, the density of heat flux which occurs due to the friction of chips against the cutting face of the mill teeth and that which occurs as a result of flank surface friction against the workpiece being machined.The dependence of the cutting temperature on the value of the tool wear has been obtained. The thermal field in the tool has been calculated. The presented results of the numerical experiment have been obtained by a customized procedure that represents a revised procedure developed by Professor A.N. Resnikov for the conditions of endmilling.  The article describes the main stages of adaptation. There are four of them, and they are based on the geometrical specificity of the chip. Immediate calculation of temperature fields in the cutting area in the endmilling process was performed using a computer finite - element model. The model takes into account the hydrodynamics of the cooling lubricant which, in most cases, takes place in endmilling and other machining processes.

VESTNIK of Samara University. Aerospace and Mechanical Engineering. 2015;14(3-2):409-417
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Procedure of creating three-dimensional solid models of tool electrodes for electrochemical pulse machining of gas turbine engine parts in CAD-systems with their parametric coupling with software module profiling
Nekhoroshev M.V., Pronichev N.D., Smirnov G.V.
Abstract

This work is dedicated to the creation of parametric solid models of tool electrodes based on the results of the calculation of the previously created software module. The developed technique will facilitate the solution of the problem of technological preparation of the operation of electrochemical machining (ECM) of a gas turbine emgine copressor. In this case, the solution could be obtained by simulations in several iterations and would completely preclude all machine work and mechanical hand-operated development of electrodes. The technique is based on a mathematical model of electrochemical shaping of a gas turbine engine airfoil using pulse current. In developing the model the electric comductivity and temperature were taken to be constant, the current output depended only on the current density, the anode and cathode overvoltage was determined by the polarization curves, the peculiarities of the anode process dynamics were considered by the current density and the parameters of the hydrodynamic conditions were taken to be optimal. A software module was developed in the course of developing the procedure. The module developed provides easy implementation of a mathematical model of profiling tool electrodes in ECM.  Electronic models of electrode profiles that could be used in producing control software for machining electrode profiles on CNC machines are the end result of such simulation.

VESTNIK of Samara University. Aerospace and Mechanical Engineering. 2015;14(3-2):418-424
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Application of the technology of pulsed laser surface coating in correcting casting defects of parts made of «ЖС-32» alloy
Smelov V.G., Sotov A.V., Agapovichev A.V., Nosova E.A.
Abstract

Production of casts of parts of gas turbine engines (GTE) is a complex and expensive process that requires a considerable amount of material resources. Various defects often occur in the manufacture of complex parts of gas turbine engines, defects that can be corrected in various ways. This paper describes a method of correcting defects in a cast alloy stator by pulsed laser cladding of stainless steel elements. After deseaming the unsound spots were reconstructed using a wire selected by matching its chemical composition with the basic material, annealing being used at different stages of surface coating. Annealing of the basic metal prior to deposition results in a two-fold increase of the transition area, the difference in the properties of the basic material and the cladding is maintained. If annealing takes place after cladding there is no clearly defined borderline between the basic materials and the steel deposited. Annealing and final hardening heat treatment is required after stainless steel is deposited on the nickel alloy.

VESTNIK of Samara University. Aerospace and Mechanical Engineering. 2015;14(3-2):425-431
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Technology of pulsed laser surface coating in pressing tool repair
Smelov V.G., Sotov A.V., Kyarimov R.R., Agapovichev A.V.
Abstract

A pressing tool is a rarther complicated device operated in the conditions of loading of hundreds of tons, periodic temperature gradients of hundreds of degrees, and subject to the influence of corrosives. The paper describes the operation of restoring the geometry of the tool by pulsed laser surface coating with filler metal feed. Laser cladding is carried out on a process installation including a pulse solid-state laser on YAG: Nd with the emission wavelength of 1.06 μm. An algorithm of optimizing the design process is proposed. Using this technique makes it possible to significantly reduce the time of technological preparation of production, as well as the proportion of pilot studies. On the basis of the developed optimization techniques process parameters of laser cladding are selected. Macro- and micro- analysis of the surface under investigation is also carried out. Microhardness of the cross section of the basic material and surface coating is measured for the comparison and evaluation of their properties. The values of hardness (HRC) are chosen according to Rockwell hardness scale taking into account suitable ratios obtained according to Vickers (HV). Measurements of the material hardness are required to identify the ability to resist elastic and plastic deformation or fracture in the case of introducing a harder metal solid that does not take permanent set in the surface layer of the material.

VESTNIK of Samara University. Aerospace and Mechanical Engineering. 2015;14(3-2):432-437
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Comparative research of algorithms of measuring the geometry of complex profiles of gas turbine engine compressor blades
Pechenin V.A., Bolotov M.A., Ruzanov N.V., Stepanova E.R.
Abstract

The paper presents three algorithms for the measurement of gasturbine engine (GTE) compressor blades airfoil (suction side, pressure side, leading and trailing edges) geometry using coordinate measuring machines. The first algorithm is a single scan of the heightwise blade section using a test point. The second algorithm is based on the pre-alignment of the nominal profile with the measured actual profile. An iterative closest-point algorithm is used to carry out the procedure of the best possible alignment of the measured ptofile and the nominal one. In the third algorithm, the coordinates of the measured points of the edges are calculated using the spline defined by the coordinates of the test point (TP) center. The research of errors of measuring the geometry of the elements using the algorithms mentioned above was carried out. To perform the research a model was developed simulating the contact of the TP and the surface of the part being measured. The model makes it possible to calculate the coordinates of the contact point, the center coordinates and the coordinates of the MT of the measured points. The search for the coordinates of the contact was performed using the method of sequential quadratic programming. A procedure was also used that makes it possible to simulate the deviation of the profile and surface position from the nominal. In the course of the simulation dependences for determining the average, lower and upper boundaries of the measurement error distribution for any airfoil point being measured were obtained.

VESTNIK of Samara University. Aerospace and Mechanical Engineering. 2015;14(3-2):438-447
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Estimation of nipple support torsional stiffness for the calculation of pipeline natural frequencies
Bezborodov S.A., Ulanov A.M.
Abstract

Natural frequencies of pipelines depend on the stiffness of their connection with equipment. As a rule, nipple supports are used as connections. The existing methods of calculation consider these supports as absolutely stiff, or neglect their stiffness at all, or take into account stiffness for translational displacement only. It leads to significant error (up to 12.7 % for the system under investigation in the present research). Experimental asessment of nipple support torsional stiffness is difficult to perform. Since many pipelines are connected in bundles, it is necessary to research the influence of the vibrations of one pipeline on those of another. A method of assessing nipple support torsion stiffness based on the correlation of experimental and calculation research is proposed in the paper. Natural frequencies of a bundle of two pipelines are obtained experimentally using a laser vibrometer. Calculation research with the aid of the ANSYS software makes it possible to find the torsional stiffness of supports about all three axes of the Cartesian coordinate system. In this case the calculated natural frequencies are close to those experimentally obtained. The results of calculation research make it possible to discuss the influence of pipeline nipple support torsion stiffness on the pipeline’s natural frequencies. The proposed method allows reducing the calculation error for the pipeline natural frequency down to 2.6 %.

VESTNIK of Samara University. Aerospace and Mechanical Engineering. 2015;14(3-2):448-453
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Conversion of gas turbine engine oil system
Boev A.A., Grishanov O.A.
Abstract

The paper emphasizes the increasingly important role of gas turbines on the power generation and gas pumping market. One of the variants of manufacturing such power plants consists in the conversion of aircraft engines into industrial gas turbine drives. The authors review the advantages of this type of production. The paper describes the operating conditions of such gas turbines and major challenges encountered in designing oil systems for aeroderivatives of this type.  Conservatism of aircraft engine developers does not make it possible to realize the changes in requirements to industrial power plants to the full extent, which results in  imperfection  of the oil system structure as it is re-designed for ground application. The paper presents the main trends in industrial gas turbine oil system development. Three levels of oil system conversion are defined: maximum (maximum possible application of the existing hardware, in which case achieving high gas turbine service life is impossible), medium (aircraft engine oil system components that do not significantly affect the engine life are partially preserved, while other components are re-designed for ground application), minimum (complete replacement of the oil system elements aimed at achieving the highest performance characteristics). 

VESTNIK of Samara University. Aerospace and Mechanical Engineering. 2015;14(3-2):454-459
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Testing of gas turbine engine bearing oil supply through an oil-catch ring
Boev A.A., Petrukhin A.G., Mikhailov A.A.
Abstract

The paper describes a defect of a high-pressure rotor radial-thrust bearing resulting in its failure. Bearing failurecould be caused by insufficient liquid coolant supply. The paper presents a method of oil supply to the gas turbine engine bearing assembly through an oil-catch ring. It also introduces and describes the oil-catch ring design. The ring features the capability of providing the liquid coolant supply in spite of the centrifugal effect. The authors enumerate the disadvantages of this method of lubricant supply as well as the advantages of the proposed design application. The paper describes the virtual structure calculation and presents the input data and the obtained results. The configuration of the ring test rig is presented. The parameters to be controlled during the test are detailed.  The test results and their comparison with the hydraulic design results are presented. Conclusion is made about the application of the oil-catch ring that proves the efficiency of using this method of supplying lubricant.

VESTNIK of Samara University. Aerospace and Mechanical Engineering. 2015;14(3-2):460-466
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Estimation of tension of the surface layer of parts after hardening by different methods of surface plastic deformation
Sazonov M.B., Solovatskaya L.V.
Abstract

A method of control of shot impact methods of surface plastic deformation is presented in the paper. The possibility of controlling the hardening process of parts made of titanic alloys in terms of deflection of plates made of carbon steels is shown. Because of differences in the resilient and plastic properties of materials and as they show different tendencies to hardening their deformation will occur with different speed and intensity over time. In the case of the greatest deflection of the testplate it may not be up to the required degree of hardening of the part made of another material. Cases of insufficient hardening or rehardening of the part’s surface layer may occur in controlling the hardening on plates made of U8A steel. One of the indices of the surface layer is its energy level, therefore the intensity of exoelectronic emission of the surface of the part treated can be used as a criterion of estimation of the stress-strain state of the surface layer. Non-destructive testing of hardening and finishing of the surface layer can be accomplished comparing the part tested with the reference standard.

VESTNIK of Samara University. Aerospace and Mechanical Engineering. 2015;14(3-2):467-473
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Calculation methods of investigating the surface layer of thin-walled shafts hardened by methods of surface plastic deformation
Bukaty A.S., Shvetsov A.N.
Abstract

Calculation methods of investigating the residual stress-strain state of the surface layer of shafts hardened by shot peening and diamond burnishing are discussed in the paper. Shafts manufactured at aircraft plants are mostly thin-walled. In addition high requirements are imposed on the accuracy of their geometric dimensions and shape. Ensuring the fatigue resistance of shafts is achieved by applying hardening treatment. Hardening treatment residual stresses result in residual deformation of shafts often exceeding manufacturing tolerances. The models and approaches proposed in this paper make it possible to predict computationally the residual stress-strain state of the surface layer after diamond burnishing as well as technological residual deformations of the shafts caused by residual stress. They also allow adjusting the modes of shot peening and diamond burnishing at the stage of process development. The work was carried out for a shaft made of VT-22 and EP517-SH materials. The results of the investigation show that the use of preliminary numerical analysis of treatment modes makes it possible to ensure residual deformations of the most critical sections of the shafts and seating surfaces for bearings within manufacturing tolerances and also to reduce tensile residual stress on the shaft surface after diamond burnishing.

VESTNIK of Samara University. Aerospace and Mechanical Engineering. 2015;14(3-2):474-480
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Development and analysis of screw restrictor hydraulic characteristics in the air bleed valve control unit of a gas turbine engine
Gimadiev A.G., Makaryants G.M., Blyumin K.V., Dudnichenko I.M.
Abstract

There is a need to change the air bypass control unit performance to estimate its influence on the compressor gas-dynamic steadiness and the combustion process in the combustion chamber during the testing and operation of gas turbine engines with low-emission combustion chamber. Setting up the required air bypass valve closed (open) time by means of standard hydraulic actuator in the process of testing requires stopping the engine, removing the air bypass control unit, changing the orifice and testing the unit’s performance on the test stand that are associated with significant time and material costs. To adjust the time of restating the air bypass control unit it is proposed a screw throttle, the parameters of which are calculated on the basis of research performance of the unit. The custom screw throttle is designed and its hydraulic characteristics are researched, its effectiveness is experimentally verified within the unit at the test stand conditions. The possibility of changing the air bypass control unit performance in a wide range at different air bypass valve reaction forces is shown.

VESTNIK of Samara University. Aerospace and Mechanical Engineering. 2015;14(3-2):481-490
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Pilot study of frequency characteristics of an acoustic probe for measuring pressure pulsations in the gas turbine engine inlet device
Ivanenko V.N., Alexandrova T.G., Dyagileva E.C., Gimadiyev A.G., Bystrov N.D.
Abstract

Special tests are carried out to determine the effect of heterogeneity of the air flow at the engine intake to the gas-dynamic stability margin of the compressor. There are acoustic probes mounted in the engine air flow meter manifold to measure pressure pulsations for this purpose. The probes are installed around the circumference of the collector at an angle of 90° relative to its axis. There is a differential pressure sensor installation in the acoustic probe due to the smallness of the amplitudes of velocity head pulsations in the manifold. Stagnated pulsed-flow of air is directed to the main input of the sensor and its damped component to the discharge chamber. In the paper on the basis of electrodynamics’ analogies the method of calculation of acoustic RC-damper to eliminate the constant and low frequency components of the flow speed pulsations is presented. To confirm compliance of the measuring probes characteristics to the design specification requirements acoustic probes’ frequency tests are conducted. Test results show that the developed acoustic probe can measure pressure fluctuations in the gas turbine engine inlet flow meter manifold with dynamic accuracy of ± 10% in the frequency range of 2-300 Hz.

VESTNIK of Samara University. Aerospace and Mechanical Engineering. 2015;14(3-2):491-500
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