Renev M. E., Kashubo Ya. D., Mashek I. Ch., Khoronzhuk R. S., Lashkov V. A.
This article is devoted to an experimental and numerical study of the influence of energy input by a combined microwave discharge with sparkless laser initiation on a supersonic flow near a model body, as well as an analysis of the energy input created by the discharge. The model is a cylinder with a flat end. The experiment is carried out to obtain shadow patterns and pressure oscillograms at the stagnation point. Numerical modeling uses a system of equations of the hydrodynamic model of electric discharges with the addition of accounting for the effect of laser radiation on the medium. For a cylinder with a diameter of 20 mm, a pressure decrease from 29.2 to 15.9 kPa was obtained at a Mach number of 2.1 and at a static pressure of 4.66 kPa, a temperature of 150 K. The duration of the time interval with reduced pressure is 160–190 μs. According to numerical estimations, the energy input is 10 mJ. During the discharge combustion, the energy input zone increases to 0.74 mm in diameter and 13 mm in length.
Chernyshov M. V.
The flowfield of a two-dimensional (planar or axisymmetric) overexpanded gas jet is analyzed in a wide range of determining parameters (such as nozzle throat angles, outflow Mach numbers, jet pressure ratios, and gas adiabatic indices) in the vicinity of the nozzle edge. Theoretically, the change in the geometric curvature of the boundary of a supersonic jet and a shock wave falling from the edge, the change in the shock strength, the vorticity of the flow, total and static pressures, and the Mach number in the compressed layer after the shock are studied in a wide range of problem parameters when the non-separation condition is met. A significant difference has been found between the differential parameters of the incident shock and the flowfield behind it for planar and axisymmetric jet flows. The outflow parameters corresponding to the zero and extreme values of the listed differential parameters are found. Some theoretical results (such as the reverse direction of the curvatures of the incident shock and the jet boundary, the local attenuation of the incident shock in the vicinity of the nozzle edge, the increase and decrease in static pressure and the Mach number of the flow behind the shock) seem remarkable and unobvious at first glance. The theoretical results obtained within the framework of the inviscid non-separated flow model are partially confirmed when compared with previous results of other authors.
Levikhin A. A., Musteikis A. I.
A one-dimensional computational methodology is proposed to investigate the influence of regenerative cooling channel parameters on the wall temperature of a low-thrust rocket engine (LTRE) chamber manufactured by selective laser melting (SLM). A computational study was performed for a model LTRE chamber made of 12X18N10T steel with a thrust of 100 N, using gaseous оxygen-hydrogen (GOX/GH2) and gaseous oxygen-methane (GOX/GCH4) propellant combinations, without a low-temperature boundary layer. The analysis considers a cooling channel with straight ribs of rectangular cross-section and several design configurations: ribs of constant width and ribs with a width varying along the channel length. The allowable ranges of chamber pressure and channel parameters were computationally determined to ensure a maximum permissible chamber wall temperature of 1100 K.
Kudryavtsev D. V.
The flight of a high-speed aircraft (HSA) at constant cruise speed along the line of sight is accompanied by heat generation. The recovery temperature at the fairing’s critical point can exceed 700 °C, which necessitates the use of a material that preserves its structural integrity while maintaining the specified radiofrequency (RF) performance. Material for the fairing is selected by determining the tensile strength and elastic modulus as functions of temperature and load. Most experimental heating chambers employ tubular electric heaters (TEHs) with spiral filaments. In a cylindrical chamber the TEHs are positioned at equal distances from the characteristic heating zone of a standard specimen, producing a concentrated infrared radiant flux in the target area. The through-thickness temperature gradient in this zone is minimal, enabling assessment of material behavior at a prescribed temperature. However, when one-sided heating of the chosen material as part of the fairing assembly is performed simulating thermal exposure from the oncoming airstream, the through-thickness gradient in the half-wave wall differs markedly from that produced by uniform, omnidirectional heating of a standard specimen. Since the purpose of ground tests is to reproduce in-flight temperatures and loads, an excessive gradient mismatch precludes obtaining reliable results. If heating is applied by a high-enthalpy, high-velocity jet, the through-thickness gradient in the half-wave wall becomes closer to operational conditions, which is essential for ground testing. In addition to surface temperature effects on the fairing, it is necessary to reproduce the service load at the most critical structural feature – the joint of dissimilar materials. Load simulation at this joint is implemented using a tie-rod system that generates a bending moment at the clamped (fixed) support. Under exposure to a high-enthalpy high-speed flow, the tie-rod structure may fail prematurely due to reduced strength, therefore local heating of the material interface – excluding the tie-rod attachment – is advisable. Local heating of the fairing assembly is carried out with TEHs using the same methodology as for standard specimens. The key challenges in local heating are reproducing the required through-thickness temperature gradient in the half-wave wall and accurately measuring the true temperature of the RF-transparent section.
Mitin F. V., Agapkin N. A.
В работе рассмотрен универсальный алгоритм управления, предназначенный для обеспечения выхода беспилотного летательного аппарата (БПЛА) на заданную высоту при различных способах взлета: вертикальном, горизонтальном, катапультном и ручном. Предложенная методика базируется на оптимизационном подходе с использованием функционала Красовского. Управляющие воздействия рассчитываются с помощью прогнозирующей модели с использованием коррекции структуры управления. Проведенное моделирование демонстрирует, что алгоритм имеет высокую сходимость. Требуемая высота достигается при разных начальных условиях. Графики управления, времен переключения и динамики системы подтверждают адаптивность предлагаемого решения. Алгоритм с коррекцией параметров структуры управления позволяет сократить зависимость от инфраструктурных ограничений и облегчает переход между режимами старта, что делает его перспективным для внедрения в автоматизированные системы управления БПЛА.
Andryushkin A. Yu., Komarov K. A., Zverev M. A.
During aircraft operation, the properties of its structural elements degrade, making the prediction of their residual life a critical task. To assess the current serviceability of a structural component, a probabilistic “load-strength” model is analyzed. Based on this model, a methodology is proposed for predicting both the mean residual life and the gamma-percent residual life of a composite strut tube. The practical significance of the developed methodology is demonstrated using the example of predicting the residual life of a carbon-fiber-reinforced polymer strut tube.
Kislitsky M. I.
The development of the small spacecraft (SSC) market necessitates the creation of a new class of space vehicles – small space tugs (SST). An analysis of SST design principles has shown that they remain operational after completing their primary mission of interorbital SSC transportation. This paper proposes the further utilization of the SST as a spacecraft to address additional mission objectives, thereby enhancing its operational efficiency. Conceptual aspects of implementing the additional use of SSTs are examined. Practice shows that rocket and space technology products commonly possess residual resources. The primary reasons for their availability are discussed. These residual resources can be utilized to accommodate additional mission-specific equipment on the SST. The payload mass for an SST as a transport vehicle is inherently variable, which can result in a reserve of transportable mass. This mass reserve can be allocated for an auxiliary payload (APL). The concept involves accounting for the systemic impact of the APL on the SST and other components of the space complex. As it leverages pre-existing hardware, this concept increases the overall output effect generated by the SST with minimal additional costs.
Meshkov S. A., Bogachev M. A., Nechayeva T. V.
In the modern world, communication plays a key role in various fields, from everyday interaction to the control of complex technical systems. With technological advancement, there is a growing need to improve information transmission methods, especially when using electromagnetic waves in open space. This paper describes an algorithm for detecting angle-modulated signals based on multi-stage processing, which includes an assessment of both energy and information characteristics. The relevance of this work is driven by the demand for reliable data transmission in aviation, maritime communications, as well as military and expeditionary systems, where HF communication remains indispensable. The results can be applied to enhance the quality of signal reception and processing in noisy environments.
Ralnikov V. D., Petrov Yu. V., Pligi n M. V., Ivanova M. A.
Additive technologies have long been used in various industries, including radio engineering. The use of various 3D printers can significantly speed up the process of prototyping and small-batch production. This paper proposes a process for manufacturing waveguide paths by the laser growth method, as well as highlights their post-processing and application features.