VESTNIK of the Samara State Aerospace University
Latest Publications

A laser-scanning rangefinder mounted on a gimbal with two degrees of freedom is presented. The rangefinder can be used as part of a navigation system of an unmanned aerial vehicle to avoid obstacles or prevent collisions. Compared to stereo cameras, the device requires significantly less computing resources and is less dependent on lighting conditions. Compared to integrated lidars, the cost of the device is by an order lower. А model of the device was developed and an obstacle avoidance flight was simulated in the Gazebo simulator. The PX4/Avoidance software was used as an autopilot. As a result of a model experiment, we found that a scanning laser rangefinder can provide autonomous navigation with obstacle avoidance.

The application of casting technologies in the production of parts and assemblies of small-size gas turbine engines is justified in the paper. The technology of vacuum casting in gypsum molds was tested during the production of an experimental centrifugal compressor of a small-size gas turbine engine. On the basis of a 3D model of the designed centrifugal compressor, computational studies of vacuum casting were carried out and rational parameters of the technological process were determined. Prototypes of the developed centrifugal compressor of a small-size gas turbine engine were made. The results of calculations and the performed technological experiment confirmed the fill rate of the gating form and the absence of short pour. The distribution of shrinkage porosity and cavities corresponds to the design values and is concentrated in the central part of the casting that is subjected to subsequent machining. The area of the blades, disc and sleeve is formed without defects. The use of casting technologies in the production of parts and assemblies of small-size gas turbine engines assures the required quality with a comparatively low price of the finished product, making it possible to achieve the balance between the cost of the technology and the quality of the product made according to this technology.

The article considers the problem of calculation accuracy when using mathematical models of gas-turbine engines of the second level of complexity, using the example of a device for mixing the flows of the core engine and the bypass duct of a gas turbine engine, and suggests methods for solving it. The processes taking place in mixing chambers of air-breather engines are considered to be difficult for mathematical modeling since the exchange of kinetic and thermal energies of the flows characterized by different velocities, pressures, temperatures and chemical composition occurs in them simultaneously. The mixer does not only ensure mixing of flows from different engine ducts, but also acts as a kind of throttle. It regulates the pressure downstream of the fan and, consequently, air consumption in the bypass duct, thus affecting directly the fan characteristics and the distribution of flows over the engine ducts. The paper presents the dependencies of the workflow parameters that allow for more accurate verification of mixer models of the second level of complexity.

The article proposes a method for designing combustion chambers for gas turbine engines based on a combination of the use of calculations in a one-dimensional and three-dimensional formulation of the problem. This technique allows you to quickly design at the initial stage of creating and development of the existing combustion chambers using simplified calculation algorithms. At the final stage, detailed calculations are carried out using three-dimensional numerical calculations. The method includes hydraulic calculations, on the basis of which the distribution of the air flow passing through the main elements of the combustion chamber is determined. Then, the mixing of the gas flow downstream of the flame tube head and the air passing through the holes in the flame tube is determined. The mixing quality determines the distribution of local mixture compositions along the length of the flame tube. The calculation of the combustion process is carried out with the determination of the combustion efficiency, temperature, concentrations of harmful substances and other parameters. The proposed method is tested drawing on the example of a combustion chamber of the cannular type. The results of numerical calculations, experimental data and values obtained using the proposed method for various operating modes of the engine are compared.

The presented work shows the necessity of organization of individual instrumental control of the content of rocket fuel and its products in the air of rocket-space industry enterprises. No accurate analysis of gas analyzers presented on the Russian market, providing individual instrumental control of concentrations of heptyl and its derivatives in the workplace air is available. Therefore, the task of express, automatic, selective and simultaneous monitoring of heptyl vapors and derivatives of its transformation in the air of industrial premises by one instrument and replacing the imported gas analyzers remains urgent. It is shown that the solution of the posed problem is possible on the basis of the optical absorption method. The requirements to be met by the gas analyzer are formulated. Approximate wavelengths at which simultaneous measurement of concentrations of heptyl and its derivatives in an air sample is possible have been determined. The ways of realization of individual gas analyzers having small mass-size characteristics are outlined. Structural schemes for infra-red gas analyzers have been proposed: multi-channel; single-channel (with frequency modulation of radiation). Tasks for further research are formulated.

On the basis of the literature review carried out, the article assesses the current state and development trends of the theory and technology of incremental forming a promising technological process for rapid prototyping of parts from sheet blanks. The basics of the process and the equipment for its implementation, the mechanism of deformation during incremental forming are described. The developed solution for exporting the trajectory of the deforming tool from the CAM to the CAE system is described.

Testing of prototypes of equipment is the most important stage of their development. The article considers a low-power high-frequency ion engine RD0310 which was manufactured and tested at the production base of the KBHA joint-stock company. The tests were carried out in a vacuum chamber with a volume of 5.66 m3, the vacuum pumping system of which allows for a pressure inside the chamber of no more than 110-5mm Hg. with xenon consumption of up to 0.7 mg/s, which is as close as possible to space conditions. During the tests, the cyclogram of starting and stopping the engine was worked out, and the thrust dependences on the flow rate of the working fluid, the power of the high-frequency generator and the voltage at the emission electrode were obtained. According to the test results, stable engine operation was achieved and the following values were obtained: the thrust of 9.1mN at a specific impulse of 3740 s.

The work contains the results of a study of the basic design concepts of advanced engines for supersonic civil aircraft, carried out in order to make a forecast for the development of aviation technology, taking into account the experience of foreign designers. Engine designs are presented that are considered to be the most rational ones from the point of view of achieving high technical and economic parameters in the range of cruise Mach numbers from 1.2 to 5. Advantages and disadvantages of various engine designs, as well as issues of engine regulation at different flight modes, are discussed. The parameters of some engines being developed and studied at present for supersonic civil aircraft are presented. The analysis of the designs shows that an increase in the cruise Mach number leads to a complication of engine designs in the direction of an increase in the number of controlled elements, the number of working fluid flow paths, a complication of the architecture of turbomachines, as well as in the direction of using combined schemes and alternative fuels. The aspiration to meet new reinforced ecological requirements through the use of new, complex engine designs that differ significantly from traditional gas turbine engines will inevitably entail additional technical risks due to the insufficient level of technological readiness of most of the new controlled units.

The paper presents the results of a calculation aimed to study the influence of ionizing, bremsstrahlung radiation on the operation of a nanosatellite obtained during the implementation of the project 0777-2020-0018 in 2020. A comparative analysis of the results of calculating the specific ionization and radiation energy losses of protons (from 0.1 to 400 MeV) and electrons (from 0.04 to 7 MeV), as well as their path lengths in aluminum according to the formulas of various authors and the database of materials of the National Institute of Standards and Technologies is presented. Based on the analysis results, the annual dose in the aluminum structure of the SamSat ION nanosatellite in a circular sun-synchronous orbit (SSO) is calculated. All calculations are based on the data of the energy spectra of protons and electrons of the SSO given in the Information system Spenvis of the European Space Agency. The results of calculating the integral fluxes in aluminum under the action of protons and electrons of a circular SSO for different thicknesses are obtained, and the fraction of passed particles is shown in the approximation of a single-layer stack. The radiation resistance of the electronic elements ISL70321SEH, ISL73321SEH and Virtex-4QV, Virtex-5QV included in the SamSat ION avionics and its ability to operate during a year was assessed.

The article presents the basic principles of three-dimensional mathematical modeling of the operation of a thrust plain bearing with fixed pads of the compressor. The model is based on the periodic thermoelastichydrodynamic (PTEHD) theory which allows calculating the temperature at the inlet to the pad and considering the complete thermal pattern. A description of the main provisions of the numerical implementation is given. In the stationary mode of the bearings operation, using the Sm2Px3Tx program, numerical experiments were carried out aimed at studying different boundary conditions to the Reynolds equation, the physics of the hydrodynamic process in the lubricating and boundary films of the bearing and the heat propagation in the body of the pad and thrust collar.