Vol 19, No 3 (2020)

Full Issue

Improving the efficiency of the powerplant of an unmanned aerial vehicle through the use of cryogenic fuel
Kolesnikov A.S., Grasko T.V., Raznoschikov V.V.

The article is devoted to increasing the efficiency of the power plant of an unmanned aerial vehicle through the use of cryogenic fuel. It has been substantiated that the creation of a power plant is based on an integrated approach to the “Aircraft – Power Plant – Fuel” system and ensures a significant achievement of perfection indicators according to high-level criteria (fuel consumption per hour (kilometer), range, flight duration, etc.) Analysis of energetic properties of some types of aviation fuels showed that gas fuels in their properties are generally superior to liquid ones, except for one thing– low density, which requires a large volume of fuel tanks. An unmanned aerial vehicle Tu-143 “Reis” (Flight) equipped with a pure turbojet engine TR3-117 was chosen as a prototype. The optimization problem of the study was solved. The task was to determine if an engine intended to run on kerosene could operate on propane according to the main parameters of the working process, provided that possible flight conditions were maintained. The obtained altitude and speed characteristics indicate that the conversion of engines from kerosene to cryogenic propane is possible without changing their design by modernizing the combustion chamber and individual elements of the automatic fuel metering system.

VESTNIK of Samara University. Aerospace and Mechanical Engineering. 2020;19(3):7-17
Disturbed transatmospheric motion of the first stage of an aerospace system
Krikunov M.M.

The paper deals with disturbed transatmospheric motion of the first stage of an aerospace system. Deviations of atmospheric density and deviations of aerodynamic force coefficients from reference values are taken as disturbances. Optimal angle-of-attack schedules for the first stage are specified. Comparative analysis of optimal control programs for disturbed and undisturbed motion is carried out.

VESTNIK of Samara University. Aerospace and Mechanical Engineering. 2020;19(3):18-30
Design of control moment gyro electric drive with strict requirements on ensuring desired rotational velocities
Polozhentcev D.S., Davidov A.A., Shipov M.G., Kazakov E.P., Malykh B.I.

The paper discusses the issues of designing a control moment gyroscope electric drive with strict requirements in terms of the accuracy of ensuring a given rotation rate of the gyro motor suspension. A brief description of the control moment gyroscope electric drive applied currently is presented and the issues of improving the electric drive characteristics are discussed. As a solution, an electric drive is proposed which operates in the mode of feedback loop using angle sensors located on the axes of the gyroscope suspension and the engine rotor. The paper describes the arrangement of the control moment gyroscopes on advanced spacecraft for Earth remote sensing and presents the analytic expressions needed to calculate the control moments that affect the spacecraft. The moments are in the projection to the coordinate system brought into coincidence with the spacecraft. The paper compares spacecraft angular velocity stabilization errors for the cases of using the conventional scheme of control moment gyroscope electric drive and the newly developed one. The presented results can be used for developing control moment gyroscope electric drives to be mounted on spacecraft of different purpose with strict requirements on ensuring operation at specified rotational velocities.

VESTNIK of Samara University. Aerospace and Mechanical Engineering. 2020;19(3):31-38
Method of coordinating joint operation of air starter and auxiliary power unit and determining the gas turbine engine starting time
Popov G.M., Baturin O.V., Novikova Y.D., Zubanov V.M., Volkov A.A., Korneeva A.I.

The article describes the method developed by the authors to coordinate the working process of the auxiliary power plant (APP) and the starter air turbine (SAT) used for starting a gas turbine engine (GTD). This method is used to test the possibility of joint operation of the APP and the air turbine in the gas turbine engine starting system in given operating modes. The method is based on combining the APP and turbine characteristics shown in the same coordinates on the same field and checking for intersection points. The condition of joint operation is fulfilled in them. Non-crossing graphs indicate the impossibility of joint work in the selected operating mode. The developed method takes into account losses and leaks in the engine starting system pipes. The data obtained using the developed method are source data for calculating and optimizing the air turbine's working process and for  determining the time required to start the GTE, as well as for testing the operability of the GTE system by strength and other criteria. An algorithm for calculating the time required to start the GTE was also developed by the authors and implemented as a computer program. The obtained data can be used to analyze the possibility of starting the engine and to calculate its main parameters for specific elements of the engine starting system, to select the APP and SAT to meet the specifications.

VESTNIK of Samara University. Aerospace and Mechanical Engineering. 2020;19(3):39-50
Optimization of honeycomb sandwich floor panels made of polymer-matrix low-combustible composite materials based on high-strength carbon and glass fibers and adhesive binder
Komarov V.A., Kutsevich K.E., Pavlova S.A., Tyumeneva T.Y.

The article deals with the task of designing aircraft honeycomb sandwich floor panels considering experimental data on the mechanical properties of new high-strength low-combustible composite materials. The developed experimental and analytical design procedure and optimization algorithm are described. The design task is formulated in terms of nonlinear mathematical programming in which the mass per square meter of the construction is the objective function. The thickness of the base layers, the height of honeycomb core and some other parameters are considered as the design variables. The proposed visual interpretation of the optimal design task allows reducing possible design solutions based on the experimental data to an enumeration of a limited number of design alternates. The article presents a demo task and the results of designing floor panes for an advanced passenger aircraft in the aisle area using a new low-combustible composite material. The floor panel is regarded as a continuous multiply supported plate loaded with distributed load. The proposed grapho-analytical method makes it possible to form the area of rational designs that differ from the optimal one in terms of mass by a specified allowable value. The performed computational and experimental analysis shows that with the use of the new material, a floor panel can be designed with base layers made of carbon or fiberglass and lightweight honeycomb filler with the mass of a square meter from 2,9 to 3,4 kg, which is the state-of-the-art.

VESTNIK of Samara University. Aerospace and Mechanical Engineering. 2020;19(3):51-72
Analytical model for determining allowances for elastomer constrained bending of aircraft parts
Moiseev V.K., Gromova E.G., Lomovskoi O.V., Mantusov M.N., Plotnikov A.N., Sharov A.A.

In the article, the authors present a method of constrained bending of aircraft sheet parts with curved sides by an elastic medium. The process of conducting constrained bending is described. A schematic description of the process is presented. The manufacture of a part is carried out in two steps. As a result of the first step, a piece is obtained with thinning in the radius part, the second step is accomplished with a unit die of reduced height. The resulting wave of excess material is deformed along the radius of the bending mandrel. In the finished part, an increase in the thickness of the workpiece is observed in the zone of the bending radius. The wave of excess material is formed due to a special allowance, the size of which is the critical factor for achieving this increase in thickness. The analytical model for determining the allowance is based on generally accepted assumptions and principles for calculating process parameters. To determine the allowance, an approximation of the shape of the excess wave by a tangential function is proposed. This allows you to get an analytical dependence that relates the geometry of the part and the thickening of the wall to the size of the allowance. The size of the allowance is limited to a certain range, the lower boundary of which is determined by the onset of plastic deformations, the upper one - by the possibility of loss of stability, leading to irreparable spoilage. The results are illustrated by graphs of the dependence of the minimum and maximum allowance for the side height on the ratios of the workpiece wall thickness, the radius of the side bending and the radius of the side in plan. Characteristic curves and analytical dependencies are presented in a dimensionless form, where the geometric parameters are assigned to the radius of the bending tool, that is, to the radius of bending of the part side on the inner surface.

VESTNIK of Samara University. Aerospace and Mechanical Engineering. 2020;19(3):73-84
Improving the efficiency of aviation turbofan engines by using an intercooler and a recuperative heat exchanger
Omar H., Kuz'michev V.S., Tkachenko A.Y.

Continuous improvement of fuel efficiency of aircraft engines is the main global trend in modern engine construction. To date, aviation gas turbine engines have reached a high degree of thermodynamic and design-and technology perfection. One of the promising ways to further improve their fuel efficiency is the use of complex thermodynamic cycles with turbine exhaust heat regeneration and with intermediate cooling in the process of air compression. Until recently, the use of cycles with a recuperative heat exchanger and an intercooler in aircraft gas turbine engines was restrained by a significant increase in the mass of the power plant due to the installation of heat exchangers. Currently, it has become technologically possible to create compact, light, high-efficiency heat exchangers for use on aircraft without compromising their performance. An important target in the design of engines with heat recovery is to select the parameters of the working process that provide maximum efficiency of the aircraft system. The article focuses on the statement of the task of optimization and choice of rational parameters of the working process of a bypass three-shaft turbojet engine with an intercooler and a recuperative heat exchanger. On the basis of the developed method multi-criteria optimization was carried out by means of numerical simulations. The results of optimization of thermodynamic cycle parameters of a bypass three-shaft turbojet engine with an intercooler and a recuperative heat exchanger in the aircraft system according to such criteria as the total weight of the engine and fuel required for the flight, and the aircraft specific fuel consumption per ton - kilometer of the payload are presented. A passenger aircraft of the Airbus A310-300 type was selected. The developed mathematical model for calculating the mass of a compact heat exchanger, designed to solve optimization problems at the stage of conceptual design of the engine is presented. The developed methods and models are implemented in the ASTRA program. The possibility of improving the efficiency of turbofan engines due to the use of complex thermodynamic cycles is shown.

VESTNIK of Samara University. Aerospace and Mechanical Engineering. 2020;19(3):85-99
Argumentation of filter width selection with the use of envelope spectrum in vibration diagnostics of rotary machine defects
Sundukov A.E.

The paper shows certain ambiguity of the narrow-band boundary of random processes obtained by different authors. The use of filters of different widths in obtaining the envelope spectrum makes it difficult to compare the obtained results by estimating the depth of amplitude modulation in vibration diagnostics of defects in rotary machines. We studied the results of bandpass filtering of the noise process only, as well as of amplitude-modulated noise. The analysis of the results of filtering of a broadband normal random process with constant spectral density and the representation of the spectrum width of the resulting oscillations through spectral moments showed that processes selected by a filter of no more than 1/3 octave bandwidth should be considered narrowband. Simulation of the amplitude of a broadband noise by the harmonic process and estimating the dependence of the modulating harmonic amplitude, the depth of amplitude modulation, skewness and kurtosis, as well as envelope characteristics on the width of the selecting filter allowed us to establish that a relative filter width of 30% should be applied when the envelope spectrum is used.

VESTNIK of Samara University. Aerospace and Mechanical Engineering. 2020;19(3):100-108

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