Vol 15, No 3 (2016)

Full Issue


Efficiency of terminal control in the trans-atmospheric first stage of an aerospace system under atmospheric and aerodynamic disturbances

Balakin V.L., Kovalyov A.V., Krikunov M.M.


Multi-step terminal control of the subhypersonic first stage of an aerospace system in trans-atmospheric climb is considered. Passive motion of spacecraft in conditions of joint influence of atmospheric and aerodynamic disturbance is analyzed. Achieving the prescribed value of the trajectory inclination angle is the terminal motion condition. Terminal height is a controlled value. An algorithm of terminal control for the formation of the command value of aerodynamic lift coefficient is proposed. The Newton method with one or more iterations at a control step is used in determining command control. The serviceability and efficiency of the algorithm compensating the influence of atmospheric and aerodynamic disturbances on the preset terminal altitude condition of spacecraft motion are analyzed. The results of simulating spacecraft motion with terminal control for maximally «rarefied» atmosphere and for different levels of deviation of the drag coefficient are discussed. 

VESTNIK of Samara University. Aerospace and Mechanical Engineering. 2016;15(3):9-16
pages 9-16 views

Spacecraft power supply system using additional low-power sources of energy

Kargu D.L., Beznyakov A.M., Nemirov A.V.


The article analyzes modern spacecraft power supply systems and possible options for extending their possibilities through the use of low-power electric energy sources (the energy of solar radiation reflected from the Earth and the energy of the magnetic field of the Earth). A conclusion is made as to the most appropriate type of spacecraft power supply systems for the use of additional low-power sources of energy. The peculiarities of operation of the proposed power supply system are discussed. A method of producing additional electric energy on board the spacecraft due to its rotation in the Earth's magnetic field is described. Mathematical models of the Earth's magnetic field are analyzed. A model of description of the geomagnetic field using a series of spherical harmonics (number of Gauss) was applied on the basis of the results of the analysis of these models to assess the magnitude of the magnetic induction in spacecraft low orbits. Based on the evaluation of the magnetic induction, the set parameters of the spacecraft and the orbit the average power of electrical energy generated by low-power sources for on-board power consumers in one orbit pass was calculated. A variant of using additional electrical energy on board a spaceship is proposed. The use of the proposed scheme will make it possible to expand the possibilities of spacecraft to receive, transform and accumulate electrical energy from primary low-power sources, which will make the spacecraft service life longer and improve its power supply capacity.

VESTNIK of Samara University. Aerospace and Mechanical Engineering. 2016;15(3):17-24
pages 17-24 views

Evaluation of the influence of the number of blades and diameter on propeller noise

Moshkov P.A., Samokhin V.F.


The article presents the results of computational and experimental research of the effect of the number of blades and the diameter on the noise of the propeller operating at Reynolds numbers of more than 106. It is shown that an increase in the number of blades while maintaining the aerodynamic and geometric similarity of the propellers and constant Mach number of the circumferential velocity leads to significant reduction of aerodynamic load noise. At the same time the displacement noise and the broadband noise increase insignificantly. Expressions are proposed that can be used to assess the effect of the diameter and the number of blades on the tonal noise and the noise of the trailing edge of the propeller provided the propeller thrust is constant. Measurements of the acoustic characteristics of light aircraft Yak-18T with two- and three-bladed propellers, MAI-223M and the F30, performed at the local aerodrome in static conditions qualitatively confirmed the estimates of the effect of the diameter and number of blades on the propeller noise. Increasing the number of blades leads to a noticeable decrease in the acoustic efficiency of engine-propeller power plants.

VESTNIK of Samara University. Aerospace and Mechanical Engineering. 2016;15(3):25-34
pages 25-34 views


Suppression of gas-dynamic self-oscillations in the outflow line of a gas control valve

Balyaba M.V., Ermilov M.A., Kryuchkov A.N., Shabanov K.U.


This article is devoted to the investigation of the causes and peculiarities of high-frequency gas-dynamic self-oscillations arising in the outflow line of gas control valves. We have demonstrated that these self-oscillations result in a substantial increase in the level of dynamic loading of the control valve elements due to the occurrence of intense tonal components in the pressure fluctuation spectra in the pipeline, the vibrations of the output flange of the control valve, as well as the external noise of the whole assembly. We have provided the results of investigating the conditions for high-frequency gas-dynamic self-oscillations arising from the gas flow interaction with the control valve elements, as well as with supporting pylons of the central fairing. It is shown that an increase in the flow above a certain value of output speed (40 m/s) results in tonal components of the spectrum of pressure pulsations. We have described the measures to suppress gas-dynamic self-oscillations by means of a perforated sleeve installed in the outflow line of the control valve. Three modifications of the sleeve design have been modeled, numerical simulation of gas-dynamic processes in the control valve exhaust duct with a perforated sleeve installed has been carried out. It is shown that complete elimination of gas-dynamic self-oscillations can be made possible by installing the sleeve in the control valve exhast duct.

VESTNIK of Samara University. Aerospace and Mechanical Engineering. 2016;15(3):35-45
pages 35-45 views

Development of the criteria of analyzing the stress-strain state of gas turbine engine parts in the elastoplastic range

Bukaty A.S., Bukaty S.A.


A dimensionless complex criterion is proposed to be used for the analysis of the stress-strain state of gas turbine parts with the purpose of diagnosing their most vulnerable areas. The criterion includes the stress-strain stiffness criterion characterizing the stress-strain type and the energy criterion characterizing the stress level of the material in elastoplastic areas. The energy criterion includes the elastic and plastic components of energy. Application of the complex criterion for the diagnostics of the most vulnerable areas of gas turbine parts and for the optimization of the geometric parameters and shape with the aim of minimizing the stress level is discussed. The efficiency of the criterion is illustrated by the example of stress-strain state analysis of gas turbine disks and by the example of varying the parameters in the process of optimization of the compressor disk structure.

VESTNIK of Samara University. Aerospace and Mechanical Engineering. 2016;15(3):46-52
pages 46-52 views

Improvement of adhesive properties and load capacity of the lubricant layer of friction units

Gromakovsky D.G., Koptev A.A., Kryshen E.D., Haustov V.I., Shigin S.B.


The results of development of the technologies ensuring an increase of wear resistance, lowering of noise and vibration level in frictional units are discussed in the paper. The most efficient technologies of formation of fluorinated microsized films on the friction surface improving the wear resistance, contact fatigue and durability of connection of the lubricant layer with friction surfaces; molecular reinforcement of surface defects decelerating the development of fatigue damages; the effect of multilubrication improvng adhesion and load characteristics of the lubricant layer, its absorbing capacity, etc. are determined. The technology of formation of fluorinated films is implemented by the introduction of graphite fluoride additive to lubricant oil. In the case of molecular reinforcement the effect of increasing wear resistance and contact endurance is connected with the passivation of surface defects formed in final treatment. Defect passivation is realized by dipping of the processed details in the oil containing solid particles in the resonant mode. In the case of multilubrication the effect of creating an underlayer of lubricant on the basis of a highly adhesive material, for example, of polimetilsiloksan produced by the JSC «TogliattiAzot» is realized. The creation of a low frequency cavitational method and installations for washing parts of friction units at the «Nadezhnost» Research and Development Center of SSTU is a important collateral development. The first installations are implemented at the JSC «Progress» Space–Rocket Center and the JSC «Aviaagregat» of the «Tekhnodinamika» Holding.

VESTNIK of Samara University. Aerospace and Mechanical Engineering. 2016;15(3):53-59
pages 53-59 views

Laser powder weld reconditioning of gas turbine engine blades

Korsmik R.S., Turichin G.A., Klimova-Korsmik O.G., Zemlyakov E.V., Babkin K.D.


The paper presents an analysis of technologies of weld reconditioning of gas turbine engine blades made of heat-resistant nickel alloys. The analysis shows that the most prevalent techniques of repair do not meet the demands of modern efficient production. An automated laser cladding machine adapted for fine cladding of blade elements of high-pressure turbines, low-pressure turbines and power turbines of gas turbine units during repairing is proposed within the framework of a joint project with an industrial partner. The weld reconditioning technology based on the principles of additive manufacturing makes it possible to reduce both the losses of material during the subsequent machining and the duration of the latter. Experimental studies on laser cladding showed that the productivity of the cladding process could be up to several tens of working blades per hour. Metallographic studies showe that the deposited layers do not contain macroscopic defects. The results obtained by the authors allow predicting high productivity of the equipment for weld reconditioning, providing high quality of the material deposited.

VESTNIK of Samara University. Aerospace and Mechanical Engineering. 2016;15(3):60-69
pages 60-69 views

Experimental research of the closed-type gas-dynamic mixer

Lepeshinsky I.A., Reshetnikov V.A., Zarankevich I.A., Istomin E.A., Antonovsky I.V., Guzenko A.A.


The article presents a new gas-dynamic mixer – a closed-type one. The structure of a two-phase flow generated by the mixer, the disperse phase velocity diagram, the size and concentration of drops are experimentally investigated. Pulsation characteristics of a disperse phase are calculated. The mixer ensures the operation of a system that produces high-concentration two-phase gas-droplet streams for various values of consumption and pressure of working fluids. It is established, that, thanks to the presence of air in a two-phase working fluid the liquid is accelerated in the initial part of the stream and then it is decelerated. It should be noted that the stream under consideration is a polydisperse one: there are sites of very small particles which the optics practically does not resolve, and there are very large drops.  The results of dispersion measurements using different methods are in close agreement. It is also experimentally established that the maximum pulsations take place at the nozzle outlet and there are local minima in the two-phase stream.

VESTNIK of Samara University. Aerospace and Mechanical Engineering. 2016;15(3):70-80
pages 70-80 views

Investigation of the gas turbine engine combustion chamber workflow

Markushin A.N., Baklanov A.V.


The article describes methods of investigation of the processes inside the combustion chamber of the gas turbine engine. The investigation is aimed at revealing changes in the combustion chamber workflow depending on the changes in the operating conditions of the gas turbine engine. Such investigations allow us to find design flaws and analyze possibilities of removing them. The main advantage of these investigations is that all experiments have been conducted in full scale. The article also presents a principal scheme of the test facility on which an engine was tested. The parameters being measured and methods of conducting measurements in the combustion chamber are presented. The conclusion is made that the implementation of measures described in the article makes it possible to analyze the intrachamber processes with the aim of developing it or testing various methods of providing its durability.

VESTNIK of Samara University. Aerospace and Mechanical Engineering. 2016;15(3):81-89
pages 81-89 views

Influence of the burner form on the combustion chamber outlet temperature field ripple for different modes of operation of gas turbine engines

Markushin A.N., Baklanov A.V.


This article describes a method of identifying combustion chamber temperature field ripple by the preparation of the set of nozzles in the engine. It shows combustion chamber temperature field ripple with a divergent nozzle and a convergent one used in the burner. The design of the combustion chamber and that of the burners are described. Diagrams are plotted that show variation in circular and radial temperature field ripple depending on the engine behavior. The combustor exit temperature field non-uniformity is assessed using such parameters as the overall temperature distribution factor, the radial temperature distribution factor and the circumferential temperature distribution factor. Comparative analysis of the results of testing two combustion chambers with different modifications of burners is carried out. Conclusions about the effect of the burner design on the temperature field ripple are made.

VESTNIK of Samara University. Aerospace and Mechanical Engineering. 2016;15(3):90-98
pages 90-98 views

The influence of booster design features on aicraft engine fan tonal noise

Khaletskiy Y.D., Korzhnev V.N., Pochkin Y.S.


Fan and booster tonal noise makes significant contribution to the overall noise level of an aero engine, particularly in subsonic modes of operation. This noise is caused by the interaction not only of the fan rotor and stator, but also by the interaction of elements of the fan and booster. Tonal components at these frequencies are caused by nonlinear interaction of rotating and stationary blade rows. Therefore, fan noise spectra contain not only common fan tonal components at the blade passing frequency and its harmonics, but sum and difference tones of interaction between the fan and booster elements. In testing acoustic characteristics of a bypass wide-chord fan it was revealed that the sum and difference components of the fan and booster interaction noise appeared in subsonic operating modes and propagated basically in the forward hemisphere. Labyrinth seal is one of the features of the actual fan design. These seals are opened and let some airflow pass in low operating modes of the fan. As a result the flow pattern upstream the fan rotor is distorted. It was experimentally determined that the seal significantly affects the generation of the fan tonal noise in subsonic modes. So far, the impact of this fan design feature is not taken into account in fan noise prediction methods. However, we experimentally determined strong influence of labyrinth seals on the noise of the aero engine simulator. Experimental assessment of the influence of the labyrinth seal operating in off-design modes on UPS noise spectra is the purpose of this work.

VESTNIK of Samara University. Aerospace and Mechanical Engineering. 2016;15(3):99-108
pages 99-108 views

Influence of fluctuation velocity on the electric conductivity of hydrocarbon flames

Shajkin A.P., Galiev I.R., Bobrovsky A.V.


The feasibility of using ionization sensor for the investigation and diagnosis of the fuel combustion process in piston power plants with spark ignition is substantiated. It is shown that in order to expand the functions and increase the reliability of operation and signal processing accuracy of the ionization sensor it is necessary to know the impact of the flame fluctuating velocity on the latter. Based on the analysis of published data and in-house research a mechanism of the effect of fluctuation velocity on the electrical conductivity of hydrocarbon flame is proposed, estimated by the value of ion current.  A formula for calculating the ion current is proposed, which includes the fluctuation velocity, the flame temperature and the concentration of carbon particles in the fuel. For methane-air flame, it was revealed that for U' < 8 m/s an increase of ion current is observed, which is due to increased flame temperature and concentration of carbonaceous fuel particles in the zone of chemical reactions of the flame. When U' > 8 m/s the ion current decreases due to the growth of heat consumption for heating the incoming fuel in the flame front, directly proportional to the fluctuation velocity. The results can be used to predict and monitor characteristics of turbulence in the combustion chambers of power plants with the aid of the ionization sensor.

VESTNIK of Samara University. Aerospace and Mechanical Engineering. 2016;15(3):109-115
pages 109-115 views

Using the phenomenon of electrical conduction of flame of non-homogeneous air-fuel mixture in design and development of combustion chamber

Shajkin A.P., Ivashin P.V., Galiev I.R., Derjachev A.D., Tverdohljobov A.J.


The use of ionization sensors for the study and diagnosis of the combustion process in gas-turbine power plants is substantiated in the paper. The review of literature data and in-house research show that thermionic emission of electrons from incandescent carbon particles plays a decisive role in the mechanism of ionization of flame sprayed in a stream of liquid hydrocarbon fuels. It is shown that as liquid fuel is injected into the circulation area of a bluff body the area of maximum concentration of electrons that determine the conduction current is located in the circulation area. When liquid fuel is injected in the flame holder the zone of maximum electron density is located in the zone between the recirculation mixing zone and the slipstream. It was found experimentally that the distance between the region of maximum electron density and the stabilizer base is determined by the quantity of the fuel sprayed, the initial temperature, the flow turbulence and the gas flow rate. The results can be used to predict and monitor the characteristics of turbulent flame in combustion chambers of power plants with the help of ionization sensors. They also make it possible to create a system of continuous monitoring and control of ignition and combustion processes ensuring minimum concentration of toxic emissions in the exhaust combustion products.

VESTNIK of Samara University. Aerospace and Mechanical Engineering. 2016;15(3):116-123
pages 116-123 views


Generation of signals with prescribed spectral characteristics

Baraboshin A.Y., Minaeva O.A.


The main causes of undesirable changes in signal frequency-amplitude characteristics at the output of modern generators are stated in the paper. A functional scheme of the waveform generator is presented. The generator is constructed with the use of home-produced hardware components. A simplified scheme of the on-board transmitting device for the small spacecraft «Aist-2» is taken as an example. The operation and interaction of units of the scheme, as well as the principle of generation of signals with various types of modulation are described. The device developed is analyzed. The units that make the most undesirable changes in the frequency-amplitude characteristic of the output signal are identified. A method of combatting bandpass flatness of frequency-amplitude characteristics is described. The spectra of the output signal prior to and after frequency correction are presented. The process of origination of parasitic amplitude modulation in a digital computation synthesizer in the case of generating signals with frequencies close to the Nyquist rate is explained. A method of combatting parasitic amplitude modulation caused by the use of a digital attenuator in the digital computation synthesizer is also discussed. It is shown that the application of the methods proposed makes it possible to develop a special waveform generator that can ensure the required spectral characteristics of the signals.

VESTNIK of Samara University. Aerospace and Mechanical Engineering. 2016;15(3):124-130
pages 124-130 views

Analysis of the features of Earth surface clutter formation in the case of low-flying target detection with the use of a bistatic radar

Vorontsova S.A.


It has been found that the usage of the bistatic mode makes it possible to reduce the power of clutter due to the decrease of the number and area of elements on the Earth surface that reflect the sounding signal. The power of these reflections to a large extent determines the signal / noise ratio at the input of the air-borne radar receiver and. as a result, the probability of correct detection of targets and accuracy of determining their coordinates. Based on the analysis of the features of the formation of reflecting patches on the Earth surface all possible configurations of these areas and analytical expressions for the calculation of their areas have been obtained. As a result of the study, analytical expressions and graphs of lines of equal distances (izodops) and lines of equal Doppler frequencies (izodals) forming these zones specific for a bistatic radar have been obtained. This has made it possible to develop a universal algorithm for calculating the power of clutter when detecting low-flying targets, which is useful for comparative analysis of the clutter power and detection characteristics for various configurations of the relative position of the receiver, transmitter and targets, as well as for comparing the detection characteristics of a monostatic and a bistatic radars. In accordance with this algorithm calculations have been performed and the graphs of dependency of the clutter power in the Doppler filter bandwidth on the frequency of their adjustment have been obtained as a result of the calculation for monostatic and bistatic radars.

VESTNIK of Samara University. Aerospace and Mechanical Engineering. 2016;15(3):131-142
pages 131-142 views

Analysis of an antenna system design for a synthetic L- and P-band aperture radar

Goryachkin O.V., Maslov I.V.


The article presents an analysis of options for designs of the antenna system for a synthetic aperture space radar (SAR), with acceptable performance characteristics in L- and P-bands. At the first stage the analysis of the current state of producing spacecraft with L- and P-band radars that use quite large folding antenna structures is carried out. It is shown that to obtain high performance of SAR in L- and P-band large folding reflectors with the diameter of up to15 meters are used. Further, variants of antenna systems are discussed and compared to determine the best combination in terms of the characteristics obtained and design complexity. An antenna system is proposed in the paper that uses antennae of the Yagi-aerial type as antenna array elements. The possibility of creating a space system consisting of several unified small spacecraft with L- and P-band SAR on board is shown.

VESTNIK of Samara University. Aerospace and Mechanical Engineering. 2016;15(3):153-162
pages 153-162 views

Resonant converter with PWM output voltage adjustment

Vorokh D.A., Makhov A.I.


A resonant voltage converter and ways of pulse width (PWM) adjustment of its output voltage are proposed in the paper. The converter has a deep (up to 90%) control range with high linearity, a high efficiency factor in the entire range of adjustment, small (1.5 ... 2 times) overload of reactive elements, weak dependence of the output voltage on the load, a low (up to 3%) level of harmonics and switching keys at zero current. The converter can be used as an efficient power supply adjustable over a wide range or a generator of harmonic oscillations with amplitude modulation on the input with an efficiency factor of over 70%. Theoretical aspects of the operation of the resonant converter are discussed and the functions of each element of the converter circuit are described in detail. The possibility of PWM control of the circuit output voltage is confirmed. Mathematical modeling is carried out using the example of highly efficient power supply and a secondary source of harmonic oscillations with low harmonics and high output power. Practical implementation of the converter circuit, operating according to the method of pulses with and without centering is analyzed. Recommendations on the optimum use of the scheme and methods considered as a complete unit are given.

VESTNIK of Samara University. Aerospace and Mechanical Engineering. 2016;15(3):143-152
pages 143-152 views

Analisys of the influence of radial displacement of a particle on the parameters of an eddy-current probe

Gudkov S.A., Kudryavtsev I.A.


The article focuses on the study of the specific application of eddy-current probes (ECP) to monitor the parameters of dispersed media. To do this, a three-dimensional finite element model of the «wear particles – ECP» was constructed in Ansys Maxwell 2015. The analysis of the the radial displacement of particles in the cross section of ECP with the help of the «Sergei Korolyov» supercomputer was carried out. It was found that the non-uniformity of electromagnetic field displacement of a particle from the axis to the periphery of the ECP results in three-fold increase of the insertion parameter. The deviation of the insertion parameters depends mainly on the geometrical position of the particle in the sectional plane of the sensor and it is weakly dependent on the frequency of the exciting field and particle size. On the basis of the established dependency we propose an ECP structure that allows mitigating the influence of the radial displacement of particles on the output signal of the ECP.

VESTNIK of Samara University. Aerospace and Mechanical Engineering. 2016;15(3):163-169
pages 163-169 views

Analysis of information characteristics of a dynamic displacement doppler transducer signal

Danilin A.I., Gretskov A.A.


The article discusses the main features of the analysis of the Doppler transducer output signal that allow conducting experiments to determine the parameters of the oscillation of rotating elements of power units. A Doppler discrete- phase method that has fewer restrictions as compared to the classical discrete-phase method is presented. The theoretical rationale for the formation of the Doppler transducer output signal in the case of its non-contact interaction with the surface of the object under control (characteristic information sections of the output signal are considered) is presented. An analysis of the output waveform near its extreme values in the presence and absence of vibration of the controlled object is carried out using the waveforms obtained in conducting the pilot study as an example. Distinctive features of the output signal due to the rotation of the rotor and the vibrational motion of the surface of the blade controlled are discussed.

VESTNIK of Samara University. Aerospace and Mechanical Engineering. 2016;15(3):170-177
pages 170-177 views

Mathematical description of the interaction between a probing microwave signal and the helicopter main rotor blade

Danilin A.I., Zhukov S.V., Popov M.S.


The paper deals with the non-contact method of monitoring the integrity of the main rotor blades of a helicopter. The available methods of monitoring the integrity of the main rotor blades of the helicopter are labor-intensive to implement, their reliability is low and they do not allow drawing a general picture of the state of rotor blades in flight. To solve this problem a method based on illumination of the blades by a probing microwave signal is proposed. Particular attention is given to the calculation of the power of the signal reflected from the helicopter main rotor blades. In deriving analytic equations it is assumed that a rotor blade is an undeformed flat metal surface. As a result, a spatial-temporal model of a probing SHF signal reflected from a helicopter’s main rotor blade has been obtained and the parameters of the model make it possible to assess the operational status of the main rotor of the helicopter.

VESTNIK of Samara University. Aerospace and Mechanical Engineering. 2016;15(3):178-188
pages 178-188 views

Peculiarities of millimeter range autodynes

Ignatkov K.A.


A functional diagram and an equivalent circuit diagram of an autodyne oscillator are presented in the paper. Features of the formation of autodyne and noise characteristics are discussed taking into account the nonlinearity of autodyne phase characteristics. Analytical expressions for the noise process are given for the case of simultaneous influence of the autodyne’s reflected self-radiation and self-noise on the autodyne. The positive influence of the use of an external high-Q resonator on the formation of low-frequency data signals is shown. It consists in the increase of the dynamic range, reduction of autodyne frequency deviation, narrowing of microwave radiation spectrum. The results of experimental research of conventional autodynes and those stabilized by an external high-Q resonator are presented in the paper.

VESTNIK of Samara University. Aerospace and Mechanical Engineering. 2016;15(3):189-196
pages 189-196 views

Research of the coefficient of reflection of the electromagnetic pulse from thin films and nanomaterials

Skvortsov B.V., Zhivonosnovskaya D.M.


The article deals with the vital task of measuring electromagnetic parameters of thin films and nanomaterials based on the sensing of surface controlled by pulsed electromagnetic signal. A method of non-contact control of such parameters as conductivity, as well as dielectric and magnetic permeability is justified. The proposed method is based on the sensing of the controlled surface by a pulsed electromagnetic signal with its subsequent analysis. Analytical relations that relate the phase and amplitude of the reflected signal to its spectral component, coefficient of reflection, self-surge impedances of the controlled medium and the signal propagation medium, as well as to the design parameters of the measurement system, such as the angle of incidence of the probing pulse and the distance to the object of measurement are presented. A brief mathematical description of the method is given. The dependence of the parameters of the reflected signal on the basic electromagnetic properties of materials is demonstrated.

VESTNIK of Samara University. Aerospace and Mechanical Engineering. 2016;15(3):204-208
pages 204-208 views

Ion source of DMS-01 scientific equipment for «AIST no 2» small spacecraft

Semkin N.D., Piyakov I.V., Rodina M.A., Rodin D.V.


The main requirements imposed upon ion sources for on-board time-of-flight mass spectrometers are considered in the paper. An approximate formula to calculate the ionization cross section of an analyte substance is given. The dependence of the probability of analyte ionization for the selected ion source design is shown. Several deigns of ion sources are proposed that provide the required width of the zone of ionization by selecting source parameters. A design of the ion source providing increased reliability and lifetime of the unit is selected for the use in scientific equipment DMS-01 installed aboard small spacecraft «AIST number 2». The results of a laboratory experiment on the operation of this design of the source are presented. The data obtained confirm the applicability of the Lotz-Drevin’s approximation formula to determine the probability of ionization of atoms or molecules of an analyte in the chosen design of the ion source.

VESTNIK of Samara University. Aerospace and Mechanical Engineering. 2016;15(3):197-203
pages 197-203 views

Influence of asymmetrical initial form imperfections on fre oscillations of thin shells

Seregin S.V.


In the framework of the theory of shallow shells we studied the effect of the initial deviations from the ideal circular cylindrical shape on flexural vibrations of thin isotropic shells. For the first time the possibility of an additional zone of splitting the flexural frequency spectrum due to the presence of initial shell form imperfections is shown in the paper. It is found that the splitting of the frequency spectrum occurs not only in cases when the number of waves of circumferential dynamic strain is equal to the number of waves of shell form imperfections  as generally agreed at present, but also in cases when the number of shape-generating waves is half that of wave imperfections. In the first case, both the split frequencies are lower than the corresponding frequency of the ideal shell. It was established that for some geometrical parameters of the shell the frequencies of radial vibrations may be commensurate with the flexural ones.  Solutions that take into account the interaction of bending and radial mode shapes are complemented with new results and conclusions. It was concluded that under the influence of periodic loads that inevitably arise in the operating conditions of shell structures, non-resonant zones defned according to the traditional approach can, in fact, be resonant. Resonance hazardous vibration conditions of shell structures with irregularities of this kind can occur at frequencies much lower or higher than the traditional theory predicted. This behavior of imperfect shells may lead to high stress-strain state of the structure and complex types of dynamic instability under operating conditions. The results and conclusions obtained in this work call for the revision of problems of the dynamics of shells with form imperfections that were solved earlier.

VESTNIK of Samara University. Aerospace and Mechanical Engineering. 2016;15(3):209-222
pages 209-222 views


Algorithm of monitoring the ecological state of coastal waters in areas of heavy economic use

Guryeva M.N., Zhuravel Y.N., Tishkin R.V.


An algorithm of monitoring the ecological state of coastal waters is presented in the paper. The algorithm makes it possible to detect oil, mineral and organic coarse pollution, thin oil films, to estimate the concentration of mineral organic pollution in the surface layer. A method of identifying shallow water zones including sand-bottomed zones and waterline phytoplankton overgrowth is presented. The pollution level of the coastal zone of the city of Regency (Brazil) is estimated using the analysis of spectral-energy characteristics of polluted and nominally clean surfaces. On the basis of the estimates obtained clustering of the initial data on the component and the total level of pollution is performed. Conclusions are made concerning total pollution of the coastal waters under consideration. An example of data processing on the basis of the algorithm presented is discussed.   A hyperspectral image obtained with the help of the «Resurs-P» No. 2 satellite is considered.

VESTNIK of Samara University. Aerospace and Mechanical Engineering. 2016;15(3):223-232
pages 223-232 views

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