Fofonov D. M.
Using the method of local variations, the process of constructing the aerodynamic configuration, based on optimizing its shape according to the aerodynamic quality criterion K, is considered. The shape of a delta wing with dimensionless length L ≡ 1 and span b = 1 was taken as the initial configuration in the optimization calculation. The shape and dimensions of internal geometric constraints are taken as the initial data. The volume of the body under study is not fixed. The optimal configuration that realizes the maximum aerodynamic quality has been determined; its properties have been studied. In the additionnal calculation, a prototype geometrically similar to the X-34 project, including the plan form and dimensions of the power plant, was taken as the initial data. The shape of the fuselage and the wing setting angle providing the maximum aerodynamic quality have been determined. An assessment of the aerodynamic quality of the resulting optimal shape shows its compliance with the required conditions.
Chernyshov M. V., Savelova K. E.
We analyzed the parameters of gas streams, which form after the triple-shock configurations occurring in Mach reflection with normal Mach shock (so-called stationary Mach configuration). We suppose that this stationary Mach configuration moves in a counter flow with arbitrary velocity (and corresponding Mach number). Analyzing relations of the dynamic pressures across the contact discontinuity, which emanates from the triple point of the Mach reflection, we have shown that the streams after the triple-shock configuration differs much in their translational action on surrounding objects.
Mikhailyuk N. V., Oborin A. I., Nilov A. S.
A comparative analysis of thermoelastic characteristics of ceramic matrix composite materials (CMC) obtained by liquid- and gas-phase technologies, reinforced with two types of carbon fibers (CF), is carried out based on different model structural-phase composition of the obtained matrix material. It is noted that when implementing the liquid-phase siliconizing and using high-modulus carbon fibers with high negative values of the absolute value of the coefficients of linear thermal expansion (CLTE), a simplified model of the matrix material consisting of only one SiC phase can be correctly used. When implementing PIP and CVI technologies, CMC with low-modulus CF and CF with low negative CLTE values show the greatest sensitivity to an increase in matrix porosity. For CMC based on CF T800, the change in the longitudinal CLTE was about 66% with a porosity of 20%. An increase in porosity leads to a decrease in all elastic characteristics of the CMC, to the greatest extent for the transverse modulus of elasticity and the shear modulus.
Andryushkin A. Yu., Gubanov D. M., Timoshenkov A. I.
. The heat resistance of polymer composite structures determines the aircraft reliability and safety. Heat-reflecting coatings applied to the surface of polymer composite structures ensure a favorable operating condition. The relationship between the defectiveness of the heat-reflecting coating and the heat resistance of the polymer composite structure is shown. A method for determining the permissible defect of the heat-reflecting coating of a polymer composite structure for characteristic temperatures is proposed. A calculated estimate of the permissible defect of the heat-reflecting coating of the fiberglass wall is given.
Vashchenko A. N., Grigoriev M. N., Zhang Zihan
The study aims to review the development and application of civil unmanned aerial vehicles (UAVs) based on the experience of China. An example of DJI, a leading global UAV developer, is provided. The interaction between China’s higher education institutions and modern national businesses, which demonstrates positive outcomes, is examined. The potential for collaboration in the education of students inclined towards entrepreneurial activities in high-tech business and business representatives is explored. The study proposes the establishment of strategic cooperation between representatives of Russia and China in the development and application of UAVs and systems based on UAV technology, serving the interests of both nations.
Grigoriev N. V.
A typical procedure for flight test data processing is the measurements smoothing to obtain the estimate of the true signal measured in flight. If the data processing is carried out in the frequency domain, it becomes necessary to estimate the frequency transform (Fourier transform) of the true signal by its measurements. A method is proposed for constructing the simplest estimate of the signal Fourier transform in the form of the low-frequency part of the Fourier transform measurements. Such estimate is determined by the single parameter – the cutoff frequency. The indicator for the estimate quality is the mean square of its deviation from the Fourier transform of the true signal. The task of constructing the estimate of the signal Fourier transform is considered as the task of finding the optimal cutoff frequency for which the criterion is minimal. An approximation of the criterion dependence on the cutoff frequency is constructed as the function of measurements only. The estimate of the optimal cutoff frequency is found by minimizing the approximation dependence. The proposed method for estimating the optimal cutoff frequency does not contain adjustable parameters. In the application to the tasks of identifying aircraft aerodynamic characteristics, it is shown that estimates of cutoff frequencies obtained by the proposed method provide identification accuracy comparable to the identification accuracy at optimal cutoff frequencies.
Anfinogenov E. V., Yakusheva M. A., Dmitriev D. K., Pobelyansky A. V., Levikhin A. A.
The features of testing microscale turbojet engines on the test bench of the D.F. Ustinov BGTU “VOENMEH” in different weather conditions and with different engine locations relative to the exhaust ventilation pipe are discussed. The problems that arise during testing of micro-scale turbojet engines are identified, and the influence of climate conditions on engine operation and test stand operation is revealed.
Bulat P. V., Chernyshov P. S., Melnikova A. I.
. For unmanned aircraft for transportation purposes, the key issue is the choice of characteristics of lifting thrusters, which should have sufficient efficiency at limited dimensions. In this paper, the methodology of numerical modeling of propeller-ring thrusters, propellers rotating in a ring, is sequentially considered. The characteristics of propellers with propellers differing in the number of blades, geometric twist of blades, degree of coverage of the area swept by the propeller and blade length are studied. Dependences of thrust and power coefficients, as well as propulsion efficiency values for a wide range of rotational speeds and engine power supplied to the propellers are obtained. The issue of propulsor optimization is considered separately. The results are compared with TsAGI reference experimental data.
Dudnikov S. Yu., Vokin L. O., Kuznetsov P. N.
. Propeller-ring propulsors are widely used on vehicles with high engine power per unit of propeller swept area (such as hovercraft and aircraft with vertical takeoff and landing capabilities). Numerical modeling allows for the selection of aerodynamic configurations of new aircraft and their engines, as well as the determination of the optimal operating modes. The characteristics of the propeller-ring propulsor in various flight modes, with different blade pitch angles, are calculated based on results of CFD experiment. The influence of the radial gap above the blade tip on the thrust and the available power of the propellerring propulsor is investigated.
Aliyeva G. V.
The article discusses optimization of detection of multiple remote objects in the infrared range by means of monostatic optical radars. Optimization problems are formulated and solved that allow increasing the efficiency of detection of multiple remote objects in the optical range. The conditions for achieving the minimum average value of the cross-section of detectable objects are determined in two modes: providing the inverse dependence of the detection distance on the minimum value of the detected signal from the targets; providing the direct dependence of the detection distance on the wavelength, i. e. in those areas where the atmosphere transmission increases with increasing wavelength.
Goychayli S. Yu., Amirova T. N.
A new methodology for validating the results of satellite measurements of soil salinity using satellite estimates of the SAVI and VSSI indices has been developed. A linear weighted sum of exponential functions of these indices has been proposed as a new soil salinity index. It has been shown that the proposed new index has an extremum in the form of a minimum of the signal in the red range. The presence of such a minimum eliminates the need to search for soil with a sufficiently high conductivity on the test site when validating the obtained large estimates of the SAVI and VSSI indices.