ISSN: 2949-401X

VOL. 1, NO, 4, 2024

Feb 22, 2024
Thermal emission cooling of aircraft elements. review of modern studies

Arkhipov P. A., Kolychev A. V.

The purpose of this article is to review the current state of research in the field of thermal emission cooling and to highlight their potential applications in astronautics and rocket science, especially for reusable space vehicles and high-speed aircraft. The article summarizes the results of the work of several research groups from several universities in Russia, the USA and China. It discusses theoretical models and experimental developments of thermal emission cooling technology, without going into detailed methodologies. The main research in this area is carried out by teams from the universities of Michigan, Colorado, Vermont and Texas in the USA with the active support of Lockheed Martin Corporation. Experimental studies of this technology are already being actively carried out at these universities. Moreover, the current findings correlate well with the results of theoretical study, from which we can conclude about the prospects of research. The effect of thermoelectronic emission makes it possible to reduce the temperature of the leading edges of the spacecraft, which is especially important for reusable spacecraft and unmanned missions, where maintaining the optimal temperature of components becomes a key factor in the service life and reliability of the system.

Selezneva M. D., Knyazev S. A., Klyus A. A., Seroshtanov V. V.

An experiment has been conducted to investigate convective heat transfer during turbulent air-flow around a heated plate with an inclined oval-trench dimple (OTD). “Medium” (L = 3 – the length of the cylindrical insert is related to the dimple’s width) and “long” (L = 5) OTDs of moderate depth at a Reynolds number of 3∙104 were studied. The inclination angle of the dimple to the free-stream flow velocity vector varied from 0 (longitudinal flowing) to 90° (transverse flowing). The heat flux was measured by using gradient heat flux sensors made of monocrystalline bismuth. The experiments were carried out in the wind tunnel of the REC “Energy Thermophysics” of Peter the Great St. Petersburg Polytechnic University. The oval-trench dimple inclination angle, at which heat transfer enhancemnt was observed exceeding the parameters of spherical or oval dimples, was determined. It has been experimentally confirmed that high-speed return and secondary swirling flows occurring in an inclined oval-trench dimple lead to an anomalous heat transfer enhancement in the inlet part of the oval-trench dimple.

Chernyshov M. V., Savelova K. E.

In this paper, a comparative analysis of methods for approximate analytical study of the parameters of the shock-wave structure (in particular, determining the height of the main, or Mach, shock) arising in planar steady supersonic gas flows (for example, in a supersonic jet flow or in a narrowing channel between two wedges) with irregular reflection of the oblique shocks is obtained. A new analytical model is proposed, which is based on the previously achieved solutions of some problems of the interaction of gasodynamic discontinuities, expansion and compression waves with each other and with various surfaces. By comparing with known numerical and experimental data, it is shown that the proposed model for the rapid estimation of shock-wave structure parameters is more accurate than the previous ones.

Levikhin A. A., Musteikis A. I., Kolosenok S. V., Kolosenok A. S.

A method was proposed for testing additively manufactured low-thrust hydrogen-oxygen rocket engines by video monitoring of the exhaust plumes in the submerged area near the nozzle. The tests started from propellants ignition at low supply rates, followed by increase up to 5 g/s of hydrogen and 20 g/s of oxygen. The choice of the spectral band allowed to detect optical emission of engine deterioration products. The images of the jet were recorded through bandpass filters and have been studied. Visual assessments of the engine condition were done after the tests. Brightness and duration of flares in jets were chosen as the main parameters and calculated from the graphic data. Their values allowed comparison of engine degradation rates during the tests.

Malkov V. M., Chakchir S. Ya., Kucherenko M. A.

The influence of the internal geometry of the channel of the passive diffusers with a second throat on its characteristics has been studied. Two schemes for organizing the compression of the channel (second throat) are considered: a scheme with central body (with pylon) and scheme with a narrowing of the canal walls (lateral compression). The optimal values of the geometric parameters of axisymmetric channels were obtained to achieve the minimum value of the launch pressure: the length of diffuser, the degree of preload, the initial angle of the pylon cone and the channel narrowing angle. A comprassion was made of starting characteristics with optimal geometric parameters for two types of preload.

Andryushkin A. Yu., Vedernikov A. Yu., Khmelevskoy N. Yu.

The durability of metal structures of airplanes and helicopters is increased by their anti-corrosion protection due to the multilayer spraying of paint coatings. Pneumatic sprayers with external mixing of paint material and air are used for spraying paint coatings. The thickness difference of paint coatings is the cause of the occurrence and development of defects and significant internal (residual) stresses. The change in the thickness of the paint coating is due to the low viscosity of the sprayed paint material, the complex geometry of the aircraft external surfaces, and the significant non-perpendicular axis of the spray jet to the painted surface. Experiments have established the dependence of the paint coating thickness on the angle between the axis of the spray jet and the painted surface. Technological recommendations for reducing the thickness of paint coatings are given.

Zakhmatov V. D.

It is proposed to qualitatively strengthen the automatic system of thermal protection and fire extinguishing of the launch equipment of mobile launch facilities, land-based and offshore stationary complexes. It is proposed to additionally equip the existing fire protection systems with multi-barrel modules (MM) of salvo spraying of water and special cooling gels, for example, of the Pyrocool type. The expediency of a system of several MM spaced around the launch pad opposite the most dangerous areas is justified so that a simultaneous volley creates a shock-wave squall of fine-dispersed water with a compacted front covering almost simultaneously (within 1-2 s) the entire range of launch structures and the area of possible emergency refills of liquid rocket fuel from distances from 50 to 200 m. Such a large range of effective extinguishing and heat and light protection distances will allow you to arrange the modules so as not to change the arrangement of the launch equipment, not to clutter the access roads and provide wave interaction of the created squalls for effective thermal protection of the launch structures from the powerful flame forces of the launch rocket engines. Each salvo of the module system creates an effectively interacting system of squalls that quickly shoot down the flame and intensively cool the volume of space around the launch structures and their complex surface. A series of volleys with flexibly adjustable intervals creates the most effective combined extinguishing and light and heat protection by surface and volumetric intensive cooling by a continuum of rapidly moving and evaporating microdrops. Intensive large-scale volumetric-surface cooling will extend the life of the launch structures and equipment, reduce the cost of pre-launch preparation, increases the number of starts without replacing equipment. The high degree of readiness for the implementation of the executive subsystem of the modules is shown on the polygon demonstration of the work of three MM, placed in a semicircle around the target and concentrated on the windward side a series of volleys on a local powerful fire of a stack of wood and tires.

Kadochinkov D. M., Kadadova A. V., Sotnikova N. V., Trilis A. V., Utkin V. V.

The article considers the possibility of optical communication for nanosatellites. A review of existing laser and receiver installations is made. Potential problems and challenges that may arise in the implementation of optical communications on spacecraft are described. The structure of optical communication hardware for CubeSat form-factor spacecraft is proposed and a review of commercially available compogents, including laser transmitters and photodetectors, is made. The range of the optical communication line for small spacecraft is evaluated. The results confirming the feasibility of this technology for nanosatellites were obtained.

Gerasimov I. M.

The article provides an analysis of the use and creation of a line of ground-based military robotic systems – a robotic tactical strike unit. Its capability of solving tactical tasks at the company-battalion level is shown. Trends in the development of military robots have been traced. The conclusion is made about the need for the functioning of a robotic tactical strike unit based on artificial intelligence, leaving the function of setting the task and, possibly, authorizing for opening fire to a human operator. The issues of the nomenclature of the elements of a robotic tactical strike unit and the interaction between robots are considered, and the critical technologies necessary to create such a system are listed.