Vol 20, No 3 (2021)

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.

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 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 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.

On the basis of the available theoretical calculations, methods for calculating the working process and power characteristics of internal combustion engines and the experimental studies carried out, a method for calculating the working process for small-sized two-stroke internal combustion engines was developed and tested. In the course of this work, the following results were obtained: the parameters of the working process and power characteristics of a small two-stroke internal combustion engine; the parameters obtained by calculation during the study of the Evolution 20GX2 engine were compared with the results of an experimental study. According to the results of the comparison, deviations in the values of the parameters of the engine under study from the results of the experimental study at the maximum power and maximum speed modes were identified.

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.

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 problem of optimal allocation of technological resources (operators) of a technical or organizational-technical system, designed to serve certain objects (operands) according to a given schedule, is considered. We take into account the necessity of incorporating, together with the main, preparatory and final operations, the possibility to select one or several operators for operand service into the service process, as well as the dependence of the operations duration on the factors characterized by uncertainty. Due to the supposed absence of statistics, expert-assigned indefinite values in the form of triangular fuzzy numbers are used. The optimization problem is formulated as a mathematical programming problem with a fuzzy criterion and clear-cut constraints, consisting in finding such a distribution of a given number of operators to serve each operand from a given set which minimizes the target function that takes into account deviations from the schedule (delay) with the service termination. Typical examples of systems for which the problem is relevant are the production complexes of air transport enterprises operating in conditions of uncertainty when it is necessary to ensure the regularity and safety of air transportation. A model example of solving the problem of allocating mobile refueling facilities at a hub airport, taking into account the peculiarities of its schedule, is presented. It is shown that the capabilities of standard personal computer software are sufficient for the solution.

The article was prepared for the 95th anniversary of the birth of Valentin Grigorievich Maslov, Doctor of Science (Engineering), Professor, founder of the school for optimal design of aircraft engine parameters, head of the engine CAD system department (Department 6) of the applied research laboratory (ONIL-2) of Kuibyshev Aviation Institute named after academician S.P. Korolyov. The stages of creating the theoretical foundation for optimal design of aircraft are discussed. The role of Professor V.G. Maslov in the formalization of knowledge in aircraft design in a context of uncertainty and the importance of multi-criteria assessment of design solutions are described. The work of Department 6 ONIL-2 (KuAI-SSAU), led by Valentin Grigorievich, provided Samara scientific school with a leading position in the field of optimal design of engines for aircraft of varying function. These works contributed to the formation of a modern understanding of the intellectualization of systems and the successful start of work in the field of their creation. The development of Professor V.G. Maslov’s ideas in the works of his students is shown.