Vol 22, No 3 (2023)

An analysis of the problems that arise when dealing with issues of increasing the efficiency of using an afterburner as part of a current aircraft engine is presented, where the complex problem of reducing its influence in non-afterburning operation and improving the work process when using it is solved. In a number of cases, solving the problem comes down to a compromise which does not allow full realization of all the advantages of the design element in question. The results of a study of the influence of the method of gas-dynamic flame stabilization on the main target indicator – specific fuel consumption in a real engine are presented, which makes it possible to justify conducting this kind of research on a real object. Graphs of changes in specific fuel consumption and thrust of a gas turbine engine when changing the engine rotor speed for non-afterburning operating modes are presented, as well as graphs of changes in specific fuel consumption and thrust of a gas turbine engine when changing the speed of the aircraft for afterburning operating modes. A conclusion is drawn about the expedience of using gas-dynamic flame stabilization in the afterburner from the point of view of its effect on specific fuel consumption.

An analysis and classification of methods for limiting technogenic pollution of the near-Earth space according to selected criteria are presented. A brief description of existing and prospective methods for limiting technogenic pollution of the near-Earth space is given, indicating the level of technological readiness and the scope of application of a particular method.

Simplified models and algorithms have been developed to estimate the current value of the angle between the normal to the plane of the solar panel and the sun vector at the time of object survey and during the reorientation of the Earth remote sensing spacecraft, taking into account the relative movement of observation objects in the field of view of the spacecraft. The models differ from the existing ones in that they do not require knowledge of the spacecraft control programs at pitch, roll and yaw angles at each moment of time of the process of its targeted functioning and re-targeting, Based on the obtained models, a software module that does not require large computing resources used in the simulation software package simulating targeted functioning of the space surveillance system has been developed, taking into account the long-term orbital motion of satellites, changes in the parameters of the orbit, the sun vector and other factors. The adequacy of the developed models was verified by visualizing the orbital motion of the spacecraft and its turns during re-targeting, as well as by comparing the simulation results with the results of analytical calculation for particular cases of the initial data. Examples of the implementation of software windows are given.

The features of the stages of parameter design calculation for the formation of the initial design of the flow path of the compressor spool of a twin-shaft engine core of a gas turbine engine are presented and substantiated. The article contains recommendations for choosing values of the pump head coefficient, efficiency and other important parameters for the  stages of medium-pressure and high-pressure spools at the stage of thermodynamic calculation. At the stage of design gas-dynamic calculation of the compressor at the middle diameter, typical distributions of axial velocity component and degree of reaction along the flow path of compressor spools should be taken into consideration. At the same time, it is necessary to provide requirements for reducing the flow velocity and static pressure coefficients in the rotor wheels and stator blades, head coefficients and Stepanov coefficients. The design gas-dynamic calculation of the compressor along the radius of the flow path is characterized by a variety of flow swirl laws at the inlet to the rotor wheels, distributions of the pressure increase and efficiency over the height of the blades. In conclusion, an example of a three-dimensional model of a compressor flow path taking into consideration the features of design calculation of the parameters of compressor spools of a twin-shaft engine core of a gas turbine engine on the basis of the appropriate flow path diagram in the meridional plane is presented.

The article discusses a stand for testing an electric propulsion system and its components. The test bench was developed for the first stage of practical research on the creation of a hybrid parallel- circuit power plant based on a piston and electric motors. The engine-propeller group was created for light aircraft with an engine power of 10…20 kW. The article presents conclusions about the conducted bench tests and the operation of the stand. Further developments of an electric motor-generator set for a hybrid power plant made on the basis of bench experiments of the electric engine-propeller combination are shown.

The article analyzes the application of various machine learning methods for solving the problem of approximating the forces of fluid film bearing lubricating layer in static formulation. The initial data on the values of lubricating layer forces for different shaft positions were obtained using a model of a rotor-bearing system based on the numerical solution of the Reynolds equation, with account for the cavitation effect. Methods for reducing the amount of calculation required to obtain the necessary data set are determined on the basis of analyzing solution approximation accuracy with artificial neural networks. After that, approximation models were constructed using a number of other machine learning methods, and the accuracy of predictions as well as the duration of the training process were analyzed. Finally, conclusions were drawn about the most effective approaches to building such models.

The article presents an adaptation of the Gaevsky-Zhidkov method for estimating the balance of high-speed small-sized internal combustion engines using the idle characteristic, as well as propeller and external speed characteristics. The main task was to develop a test bench that provides high accuracy, repeatability of measurements and the ability to test internal combustion engines with working volume of up to 3.5 cm³ at shaft speeds of up to 37,000 rpm. The test bench makes it possible to determine the characteristics of the “engine-propeller”, the no-load characteristic, and also to carry out quick reconfiguration of the test facility when changing the internal combustion engine structure. As a result of the experimental study, the propeller characteristics of seven propellers, the no-load characteristics for the base electric motor and an electric motor with imbalance were determined. Using these results, the external speed characteristics of an internal combustion micro-engine with working volume of 2.5 cm³ were compared for two levels of balancing.

The results of research in the field of development of technology for the manufacture of hybrid composites according to the scheme of directional fiber netting are presented. Reinforcement is carried out by combining carbon fibers and metal wire, impregnation with a polymer binder by infusion. The results of experimental evaluation of the tensile strength of composites reinforced only with wire, as well as hybrid samples with different percentages of carbon and metal fibers are presented. A significant dependence of the strength of the hybrid composite on the volume ratios of reinforcing materials and technological factors has been established. Design and technology recommendations aimed at improving the functional parameters of the hybrid composite are formulated.