ISSN: 2949-401X

VOL. 1, NO, 2, 2023

Jul 14, 2023
Rearrangements and transformations of shock-wave structures under the interference of oblique shocks under conditions of ambiguity and hysteresis

Bulat P. V.

Using the example of the interference of symmetrical opposite oblique shocks (a problem similar to the reflection of an oblique shock from a wall), the problem of hysteresis in the processes of transition from regular to Mach reflection and vice versa is considered. Brief information about the mathematical theory of rearrangements of shock waves and shock-wave structures is given. It is shown that there is a unique and complete classification of admissible forms of rearrangements. The interaction of opposite shocks has been studied numerically and experimentally by the hydroanalogy method. The conclusions from the theory and the results of numerical and full-scale studies are compared. It is shown that the transition from regular to Mach reflection occurs in accordance with the detachment criterion (in the Englishlanguage references) or the criterion of the maximum rotation angle at a given shock intensity (in the Russian-language references) and the principle of maximum delay (a term introduced in the singularity theory of smooth mappings). Such a transition is accompanied by an abrupt change in the intensity and angle of inclination of the reflected shocks. The transition from Mach to regular reflection occurs according to the criterion of a stationary Mach configuration (in terms introduced by V. N. Uskov), which corresponds to the Maxwell principle in the singularity theory of smooth mappings.

Kosyakov S. I., Kulichkov S. N., Mishenin A. A.

The problem of studying the structure of the leading-edge shock wave front is solved by comparing the experimental data with the results of experiments and calculations. The analyzed results were obtained by summarizing published experimental data or our own experiments, numerical and analytical calculations. It is shown that the width of the leading-edge shock wave front follows the universal (regardless of the nature of the source) energy similarity law expressed in cylindrical coordinates. Its pressure profile is described by an exponentially convex function. Recommendations for the practical application of the results in experimental studies are suggested.

Potanina E. Yu., Litvinov V. L., Guskov A. V., Milevsky K. E.

Jetting in cylindrical cumulation is an elusive process. The paper investigates cumulative jetting dur-ing the compression of cylindrical shells by means of a hydrodynamic model and numerical simulation. A method for improving jetting in cylindrical cumulation and normalizing the temperature in the jet formation zone – using a small diameter tube inside the main cladding made of refractory ni-obium – has been proposed and substantiated. The critical factor in the jet formation zone is out-lined. Thus, suggestions were made to improve cumulative jetting in cylindrical cumulation.

Samokhvalov V. N., Chernikov D. G., Yusupov R. Yu., Kibisov O. I.

The possibility and efficiency of intra-channel cooling of an inductor system with a magnetic field concentrator, used in the processes of pulsed magnetic metal processing, by a low-temperature air flow from a vortex tube with an ejector are considered. It has been established that the proposed method and device have a sufficiently high efficiency and a high process safety.

Andrievsky B. R., Popov A. M., Mikhailov V. A., Popov F. A.

Artificial intelligence methods have been actively developed in recent decades and are widely used in various fields of technology, industrial production, security, information processing, linguistics, scientific research, and many others. Currently, AI technology is the defining direction in the task of creating modern UAV control systems. Characteristic features of an intelligent system are the presence of a goal setting, the ability to manage system resources to build a strategy to achieve the goal, and feedback to control the results of their actions. This article presents an overview of such AI applications as UAV mission planning, application of AI methods for UAVs engaged in civil engineering and agriculture, space systems, UAV trajectory planning, ensuring UAV reliability and autonomy, for implementation of onboard control systems, computing aspects of UAV control and their groups, including organization of communication between them.

Meshkov S. A., Bogachev M. A.

Signal processing algorithms are necessary for the correct recovery of information in the carrier message. The question of the relevance of existing methods arises. Digitalization and the use of innovative technologies make it possible to create fundamentally new highly efficient processing algorithms. The paper proposes an algorithm that proceeds as a digital automatic gain control device that is capable of processing discrete signals of arbitrary duration. The resulting algorithm is characterized by high speed and low value of incidental amplitude modulation after processing.

Andryushkin A. Yu., Butsikin E. B., Li ZhenNing

The article examines the effect of 3D printing speed on the accuracy of the product. According to the results of the study, the achievable and feasible accuracy of the additive machine was determined. The relationship between the geometric accuracy of the product and the performance of the additive machine is shown. The following parameters of the technological mode have a decisive influence on the accuracy of the product and the performance of the additive machine: the degree of filling of the product body and the 3D printing speed. The minimum shrinkage of the material during the FDM-based layer-bylayer synthesis of the product is observed when the product body filling percentage is 100%. It is established that the achievable accuracy for an additive machine is observed at a minimum 3D printing speed. The maximum 3D printing speed with acceptable accuracy of the manufactured product corresponds to feasible accuracy. The parts manufactured by layer-by-layer synthesis with IT14 grade quality ensure complete interchangeability in many units and machines.

Bulat M. P., Kirshina A. A., Kirshin A. Yu., Nikitenko A. B.

Studies have been carried out on the ultimate bearing capacity and service life of a gas-dynamic bearing for use in a gas turbine engine of an aircraft maneuvering with overloads up to 10g. The design of the bearing uses retaining vanes that form a damping layer, which allows it to be used at high overloads without the threat of oscillatory conditions. Retaining vanes distinguish the studied gas bearing design from the classic first generation vane bearing. The experimental setup and test procedure are described. The ultimate bearing capacity is determined taking into account the overload. The process of grinding in the antifriction coating of the bearing vanes, the nature and effect of wear on the characteristics of the bearing capacity are studied. The result showed that in the selected dimension, the gas dynamic radial bearing has a bearing capacity sufficient for use in a gas turbine engine. The equivalent flight hour-based service life of the bearing unit is determined.

Ustinov A. N., Babuk V. A., Nizyaev A. A., Atamasov V. D., Kudinov A. A.

Methods for the disposal of orbital debris by artificial plasma formation (APF) are discussed, which can be carried out both with the help of a special-purpose disposal spacecraft and by means of spacecraft self-disposal functions. It is proposed to use the aerodynamic drag of atmospheric traces to decelerate an artificially created plasma formation surrounding fragments of space debris. An increase in the aerodynamic drag of the disposed space debris created by gas-dust filling of voids between solid fragments of the debris cluster reduces the space debris existence time. Being subjected to ionization under the influence of cosmic radiation or laser irradiation produced from the CAU, the plasma formation “splices” the gas-dust environment with debris elements by electrostatic Coulomb forces. In the case of using a gas-dust cloud enveloping solid fragments of debris, physical processes are formed that lead to the creation of Coulomb interaction forces. The cloud of fine-dispersed formations (FDF), even before the meeting with the debris, will be subjected to ionization due to radiation emanating from outer space, or due to its additional scanning with a laser beam of sufficient power. In order to obtain a higher concentration of the FDF ionized medium, it is necessary to introduce easily ionized alkaline and alkaline-earth substances with a low ionization potential into its composition. At the same time, electrostatic Coulomb attractions become able to overcome the dissipating forces of the aerodynamic effects of traces of the Earth’s atmosphere, that is, to preserve the APF until its dense layers are reached, in which the thermal utilization of space debris is carried out. The features of a self-disposing spacecraft are the presence of transforming structures of hull elements. The transforming structures were developed at the design stage in order to significantly increase the total spacecraft midsection after the command for its disposal is activated. The spacecraft elements are then dispersed in a larger volume of the structural form of solid space debris. On the basis of the resulting pattern of space debris, an artificial plasma formation is formed, consisting of an easily ionized gas-dust medium injected by a special-purpose generator provided for at the design stage of the spacecraft, and solid space debris. In order to preserve in space and in time the maximum area of the total midsection of such an artificial formation in order to force aerodynamic drag of Earth’s atmospheric traces, the APF is put into rotational motion. This reduces the time of existence of orbital debris.