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A comprehensive study is reported on high- and hypervelocity impacts of a steel ball simulating a space debris particle on shielded targets. Experimental studies of high-velocity impact of a steel ball were performed in the velocity range up to 2500 m/s. The obtained data were used to verify the mathematical model and numerical algorithm. Numerical simulation of the space debris impact on a shielded target was carried out in the impact velocity range 1400–7000 m/s using the finite element method implemented in the original EFES software package. The proposed failure algorithm can describe the material fragmentation and the formation of new contact boundaries without computational mesh distortion. The specific features of shock wave processes and the destruction of the target and ball were investigated at different impact velocities. [ABSTRACT FROM AUTHOR]

An analytical-experimental method has been used to investigate the penetrative capability of cylindrical VNZh-90 and VNZhK + 75% VK8 with flat heads and conical noses in interaction with a steel barrier in the velocity range of 1200–1300 m/s. Calculation results are presented for interaction of the considered strikers with steel barriers at impact velocities of up to 2000 m/s. [ABSTRACT FROM AUTHOR]

An experimental-theoretical assessment has been made of the minimum required velocity for through penetration of 20–60 mm thick steel barriers by a supercavitating VNZR-95 alloy striker. Parametric calculations have been conducted within the framework of an elastic-perfect plastic Prandtl–Reuss model. [ABSTRACT FROM AUTHOR]

A mathematical model has been constructed and verified for the behavior of a composite barrier under the conditions of shock-wave loading. An analytical-experimental method has been used to assess the effects of a modified composite barrier in high-velocity interaction with a spherical steel striker in the velocity range of 500–1200 m/s. [ABSTRACT FROM AUTHOR]

High-temperate vacuum sintering has been used to obtain porous composite tungsten carbide alloy TNIC (W–Ni–Fe–Co) + 69 wt.% WC. The results of investigations into the microstructure and physical-mechanical properties of the alloy are presented. An experimental investigation has been conducted into the high-velocity interaction of cylindrical strikers made of this material with steel plates in the velocity range of 1200–1400 m/s. [ABSTRACT FROM AUTHOR]

An experimental and theoretical study of the combustion of granulated charges consisting of pyroxylin powders in a manometric bomb of constant volume is presented. A comparison was made of the experimentally measured dependence of pressure increase in a manometric bomb with calculations according to thermodynamic model of combustion of a gunpowder sample in a manometric bomb using the empirical law of the dependence of the burning rate on pressure and a conjugate model of unsteady combustion of gunpowder. The unsteady rate of burning of pyroxylin powder, due to the high rate of pressure growth in the manometric bomb, differs from the quasi-stationary speed. This difference depends on the rate of pressure growth and on its absolute value and decreases with increasing pressure. [ABSTRACT FROM AUTHOR]

Abstract—The analysis of supercavities formed during the high-speed motion in water of two closely spaced supercavitating strikers is performed. By comparing geometric characteristics of supercavities, the possibility of qualitative assessment of influence degree of closely spaced strikers on each other is shown. By the example of two strikers, the characteristic distance between them was determined, at which the minimum mutual influence of the strikers on each other is observed. [ABSTRACT FROM AUTHOR]

Results have been presented of intraballistic design work aimed at identifying the main characteristics of a small caliber laboratory launcher and the composition of the propellant charge for various striker masses. Technical solutions have been obtained for sabots of supercavitating strikers accelerated in a small size laboratory ballistic installation. The level of the pressure acting on the striker, as it enters the water directly from the barrel of the installation, has been determined. Travel path ranges have been calculated for supercavitating strikers accelerated in a small size laboratory ballistic installation. [ABSTRACT FROM AUTHOR]

A promising direction in barrel ballistics aimed at increasing the muzzle velocity of a projectile is the use of new propellants as an attached charge. This paper presents an experimental and theoretical method for determining the law of propellant combustion in a manometric experiment (in a closed volume). Within the framework of this method, a small number of experiments could be sufficient to determine a change in the law of combustion during the propellant burnout and depending on pressure. This method is demonstrated on the example of processing three experiments with model high-density propellant. The laws of combustion of high-density propellants, obtained in this study, can later be used to calculate the gas-dynamic parameters of a shot from a barrel system or a nozzle bomb (in a semi-closed volume) using these propellants. [ABSTRACT FROM AUTHOR]

The combustion of a model high-density propellant (MHP) under the conditions of a closed volume has been investigated. A description is given of the main components and mechanisms of the manometric bomb being used. Procedures are described for determining the laws of propellant combustion in a manometric experiment, and a comparison is made of computational-experimental data. The distinctive features of the formation of an MHP combustion surface in various containers have been identified and described. The dependences of the layer combustion velocity of two model high-density propellants on pressure have been determined. [ABSTRACT FROM AUTHOR]

Experimental-theoretical investigations have been conducted into underwater supercavitating motion of cone strikers from various materials in a broad range of velocities. An estimate of the range of strikers' velocities has been performed for the implementation of their nondestructive entry into water and motion in it in a supercavitating regime. A possibility of an accurate hit by supercavitating strikers on underwater barriers in a supersonic range of motion velocities has been shown. [ABSTRACT FROM AUTHOR]

The interaction of supercavitating strikers with obstacles placed in water was investigated in a wide range of intersection angles. Several options of the interaction of strikers with obstacles are considered, including through puncturing, destruction of the striker, and ricochet. Estimation was made of the magnitude of the decrease in the speed of strikers in the cases of through puncturing and ricochet. [ABSTRACT FROM AUTHOR]

The erosion of a straight cylindrical tube by the example of a small caliber (30 mm) laboratory smoothbore ballistic unit during experimental gas dynamics studies is considered. For its diagnostics a non-contact analog-to-digital measuring device allowing for determination of the coordinate of the measured section and a software package for processing the obtained data were developed. A geometric model of the detecting unit with the location of three distance sensors in the vertices of a regular triangle is presented. A prototype of the device was assembled and tested, which allows measuring the internal diameter of the smooth bore channel of any length with a caliber of 30 mm and to record the results in the computer memory in real time. Quantitative erosion of the breech face after a series of tests is given. To compare the results, a comparison is given with the readings of a certified bore micrometer. The results of gas-dynamic analysis of one of the experiments are presented in the form of diagrams of maximum pressure, gas temperatures, and the inner surface of the barrel. The highest pressure and temperature values occur at the breech face compared to the entire length of the barrel, which confirms the erosion profile. In this case, the temperature of the inner surface of the channel is much lower than the melting temperature of steel. However, in some experiments, the internal surface temperature reached a value of 980 K and higher. At this value, the strength of the steel becomes comparable to the shear stresses of the gas flow, which causes detachment and entrainment of metal particles. The use of the developed device and software package makes it possible to improve operational safety, as well as to reduce time and material costs for repair and maintenance of installations. [ABSTRACT FROM AUTHOR]

A mathematical model has been constructed for the behavior of a tungsten carbide alloy on the basis of TC8 (tungsten carbide, 92%; cobalt, 8%) and WNFC (W–Ni–Fe–Co), or TNIC (tungsten, nickel, iron, and cobalt), in conditions of shock-wave loading. A scheme has been suggested for the process of mass loss and self-sharpening of the striker in dynamic interaction with the target. The computational-experimental method has been used to investigate the capacity of cylindrical strikers made of this composite to penetrate into a steel target at an impact velocity of 1260 m/s with account for the dependence of yield stress on the intensity of plastic deformation considering both the stage of strengthening and the stage of its structural softening in the process of deformation. [ABSTRACT FROM AUTHOR]

This article presents the results of external ballistic investigations of motion in the air of supercavitating strikers cannon-launched in a group, and a gas-dynamical picture of flow past two strikers in the chamber of an aerodynamic installation. Mathematical simulation of the process of flow past two strikers has been carried out, and their aerodynamic coefficients have been calculated. The conditions for cannon-launching of a group of supercavitating strikers have been determined that provide for their motion along the aerodynamic portion of the route and their subsequent entry into water with an angle between the longitudinal axes of strikers, at which their motion is stable. [ABSTRACT FROM AUTHOR]

Results are presented of an experimental-theoretical investigation of the motion in water of supercavitating strikers made of steel and aluminum and tungsten (TNI, i.e., tungsten, nickel, and iron) alloys in a broad velocity range. Estimates have been made of the ranges of velocities of entry into water in which the investigated supercavitating strikers from various materials are not destroyed and preserve the original shape. Experimental and computational data have been obtained on the value of deviation of the trajectories of two simultaneously starting from each other supercavitating strikers at the initial stage of their group motion in water depending on the materials they are made of. [ABSTRACT FROM AUTHOR]

Analysis has been made of the ballistic characteristics of the shots, and a powder grade has been indentified for a propellant powder charge ensuring the lowest level of force action on the projectile assembly including a group of supercavitating strikers in a gun-start. [ABSTRACT FROM AUTHOR]

The paper presents the methodology elaboration for the investigation of a high-speed impact interaction between the projectile and a split target. The impact interaction speed ranges between 1500 and 2500 m/s. The split target consisting of a polymethyl methacrylate target and a witness target made of D16 aluminum alloy, is placed at a 60 mm distance from the latter. Using mathematical simulation, all effects that occur during the high-speed impact interaction, are analyzed more precisely. [ABSTRACT FROM AUTHOR]

Results of a complex experiment-calculated investigation of the structure of a nonstationary gas flow in the working path of a hypersonic ramjet engine are presented. Methods of experimental determining the pressure and temperature distributions over the wall of an axisymmetric channel of complex geometry with a sudden widening are proposed and described. The problem on the gas flow over a ramjet engine positioned in a wind tunnel was solved. [ABSTRACT FROM AUTHOR]

Using the computer-based simulation method within the scope of continuous mechanics, impact interaction with a speed of 3000 m/s between a steel ball and a transparent armor target is calculated (the target has three layers). The face layer of the transparent armor is made of aluminum oxynitride; the middle layer, of hardened glass; and the lower layer, of polycarbonate. The influence of the angle of the projectile approach to the target and thickness of the hardened glass layer on the process of target penetration is studied. [ABSTRACT FROM AUTHOR]

An experimental procedure has been developed to record phenomena in impact destruction of a container with a fluid. The phenomena were recorded using x-ray pulse devices and a high-speed filming technique. The propagation of compression waves in the fluid was registered using bubble-markers in the form of air curtains in the fluid mass. The pressure in the compression wave was measured by a gallium arsenide crystal-based sensor. An investigation has been made into the characteristics of the phenomena occurring during the destruction of a container with a fluid by a high-speed striker. We have established the dependences of cavity development in the fluid, the striker motion law, the time dependence of pressure, and the pressure attenuation in the fluid. The obtained dependences make it possible to establish objective physical data on phenomena in impact-stressed containers and to solve the issue of strength of a container with a fluid. [ABSTRACT FROM AUTHOR]

The investigation is devoted to an experimental and theoretical research into the high-velocity motion of a group of supercavitating kinetic strikers in water. An experimental launching technique has been developed, and investigations have been conducted into the high-velocity motion of a group of supercavitating strikers on a hydroballistic testing facility, and a calculation procedure has been developed for modeling possible deviations of the strikers′ motion in water in a group start. Experimental data have been obtained on the motion of one and two supercavitating strikers on the initial portion of the path at velocities of the order of 1200 m/s, which serve as initial conditions for identifying the strikers' deviation from the target at a distance of up to 100 m. [ABSTRACT FROM AUTHOR]

The ballistic resistance of a combined cermet material based on a high-hardness ceramic bound with an intermetallide on a high-strength metal substrate, (TiB2 + NiTi) + Ti, is compared with that of plates of steel, VT1-0 titanium alloy, and Al2O3 corundum ceramics upon an impact with a steel spherical impactor in the region of velocities of about 2500 m/s. Experimental studies of protective barriers upon a high-speed impact were conducted using an experimental high-speed ballistic test bench. Mathematical modeling is based on a model of porous elastoplastic medium with allowance for various mechanisms of material destruction, which was modified for media with a complex composition. It is shown that, in the considered range of impact velocities, during penetration of barriers, the (TiB2 + NiTi) + Ti material, despite its low surface density, exerts a greater force on the impactor and exhibits greater penetration resistance than steel, titanium, and ceramics. [ABSTRACT FROM AUTHOR]

We propose a series of experiments aimed at analysis of peculiarities and revealing general regularities in the penetrability of strikers made of a composite material based on tungsten + nickel + iron + cobalt alloy with an admixture of highly rigid refractory titanium–tungsten carbide particles in various initial conditions. In particular, we have analyzed the effect of the initial temperature of the striker in the interval from –50 to 50°C on the penetration into a steel obstacle experimentally and by calculations. It is found that the initial temperature of the striker does not noticeably affect the penetration depth in the obstacle at impact velocities up to 2500 m/s. The penetrability is found to be 20% higher than that for a monolithic massive analog made of VNZh-90 alloy. [ABSTRACT FROM AUTHOR]

On the basis of an experimental and theoretical approach, the authors have considered an algorithm for modeling the behavior of advanced propellants in barreled systems of varying caliber. The proposed algorithm makes it possible to conduct preliminary investigations into the possibility of using advanced fast-burning propellants in the existing barreled systems and in advanced systems of varying calibers and for various purposes. A possible increment in the muzzle velocity of a projectile due to the advanced propellants added to the propellant powder charge is assessed without full-scale testing. [ABSTRACT FROM AUTHOR]

In this study, we perform calculations and experimental studies of the destruction of composite impactors from a porous tungsten–nickel–iron–cobalt alloy with 10 wt % tungsten titanium carbide at high-speed impact with steel barriers. In ballistic tests over a wide range of velocities, there is a significant excess of the penetration depth of these impactors into steel barriers compared to the mass-dimensional analog of a tungsten–nickel–iron alloy with 90% tungsten content. Based on the analysis of crater morphology and the structure of impactor fragments after introduction into the obstacle, we assume that the impactor is "self-sharpened" by localizing plastic deformation, which reduces the effective interaction area and increases the penetration depth. To describe the destruction, we modified the mathematical model of a porous ideal elastic-plastic body with a complex structure with the possibility of considering the adiabatic shear mechanism during interaction between the impactor and the obstacle. [ABSTRACT FROM AUTHOR]

A mathematical model of a shot from a smoothbore ballistic installation for a gun start of a group of supercavitating strikers has been developed. To verify the mathematical model, experimental investigations into high-velocity launching of a group of bodies on a hydroballistic testing facility have been conducted. A comprehensive parametric investigation has been conducted to determine conditions for loading the ballistic installation to achieve the required muzzle velocity, ensuring a supercavitating regime of motion for a group of strikers in water. [ABSTRACT FROM AUTHOR]

The paper is devoted to the investigation of the high-velocity motion of supercavitating kinetic strikers in water with account of the intraballistic processes in the powder chamber and outside the channel cut of the ballistic installation, the supercavity dynamics, and also the interaction of the strikers with underwater barriers (obstacles). The process of supercavitating motion at underwater start is modeled on the basis of solving Reynolds-averaged Navier–Stokes equations with turbulence equations and cavitation equations for a multiphase medium. To investigate the stressstrain state and a possible destruction of solid bodies in interacting with underwater barriers of various types, mathematical modeling is conducted on the basis of an elastoplastic model of a medium. The range of investigated velocities is 50–850 m/s. [ABSTRACT FROM AUTHOR]

Using high-temperature sintering, tungsten-carbide alloy-based specimens with improved functional properties have been explored. The penetrative capability of strikers fabricated of these samples into a steel barrier at an interaction speed of 1300 m/s has been investigated in comparison with that of the mass and size of a VNZh-90 alloy-based analogue. [ABSTRACT FROM AUTHOR]

High-velocity motion of a set of supercavitating kinetic strikers during their simultaneous entry into water has been experimentally studied. A special experimental method of launching supercavitating kinetic strikers and studying their high-velocity motion under hydroballistic test setup conditions has been developed. Experimental data on the motion of two identical supercavitating strikers in the initial stage of trajectory at velocities about 1100 m/s have been obtained, which demonstrate the possibility of stable propagation of a set of such strikers in water until reaching an underwater target. [ABSTRACT FROM AUTHOR]

In the present paper, we report on the results of an experimental study of the possibility to control the transonic buffet on a rectangular wing using plasma vortex generators. The influence of the developed device on the flow consists in creating a longitudinal vortex in the boundary layer as a result of asymmetric energy supply at the surface of a small vertical wedge. The experiments were performed using a wing model with a supercritical airfoil in the range of free-stream Mach numbers 0.73 to 0.78 and Reynolds numbers Re = (2.64-2.8)·106. The experimental data obtained using the method of high-speed schlieren visualization and pressure distribution measurements in the wake of the model show that the technique allows one to control both the average flow characteristics and the characteristics of shock-wave oscillations. [ABSTRACT FROM AUTHOR]

A series of high-voltage (20–50 kV) DC power sources (1–10 kW) was developed based on the circuit of high-frequency conversion with wide-range regulation of the output voltage via conversion frequency tuning. A sinusoidal current shape provides switching of power transistors at the zero current and the short-circuit protection in a load. The source provides an output voltage with small ripples and, when powered from a three-phase network, it does not require a smoothing mains filter. [ABSTRACT FROM AUTHOR]

Results of a complex experiment-calculated investigation of the structure of a nonstationary gas flow in the working path of a hypersonic ramjet engine are presented. Methods of experimental determining the pressure and temperature distributions over the wall of an axisymmetric channel of complex geometry with a sudden widening are proposed and described. The problem on the gas flow over a ramjet engine positioned in a wind tunnel was solved. [ABSTRACT FROM AUTHOR]

Aminomethylation of harmol (7-hydroxy-1-methyl-β-carboline) was investigated. It was shown that the reaction proceeds chemoselectively to form 8-aminomethyl derivatives by the action of aminals or a mixture of a secondary amine with paraform. When primary amines and an excess of paraform were used in the Mannich reaction, 2,3-dihydro-1H-pyrido[4',3':4,5]pyrrolo[3,2,1-ij]quinazolin-4-ol and 1,2,3,11-tetrahydro[1,3]oxazino[6,5-g]pyrido[3,4-b]indole derivatives are formed. [ABSTRACT FROM AUTHOR]

Peculiarities of the motion of one and two supercavitating strikers in water upon their simultaneous entry into water at speeds exceeding the speed of sound in the medium are considered. Conditions have been developed to ensure nondestructive entry of strikers into the water and stable movement along an aiming trajectory in the transonic speed range. A stable joint motion of two strikers in water at supersonic speed is obtained. [ABSTRACT FROM AUTHOR]

The paper studies the behavior of ceramic porous tungsten alloy with reinforcing agents under the shock-wave loading conditions. Penetrating capacity of tungsten kinetic energy projectiles is calculated and experimentally investigated during their high-speed impacts on steel plates. It is shown that the increased penetration depth of tungsten projectiles exceeds that of the prototype with relevant weight and size, made of tungsten-nickel-iron cast alloy. A mathematical model is developed together with the design technique of the behavior of tungstennickel-iron-cobalt metal foams alloyed with boron carbide, tungsten titanium carbide and tungsten carbide during the high-speed impact interaction. The composite ceramic material is described here as a porous medium. The matrix of this medium is a homogeneous two-phase mixture of the tungsten-nickel-iron-cobalt system and reinforcing agents added in the required proportions. [ABSTRACT FROM AUTHOR]

The possibility of improving the physico-mechanical characteristics of composite materials used in protective structures against a high-speed impact is considered. By means of self-propagating high-temperature synthesis, a two-layer cermet is obtained: the front layer is a cermet based on titanium diboride with a titanium nickelide bond, and the back layer is a titanium alloy. The study by the computational-experimental method of the impact resistance of this composite in comparison with a homogeneous titanium plate showed a qualitative advantage expressed in the absence of a shock crater in a cermet plate after a collision with a steel spherical impactor and stronger deformation and prefracture of the impactor. The two-layer cermet has a high resistance to the penetration of the steel impactor. [ABSTRACT FROM AUTHOR]

Consideration is given to conditions ensuring stable high-velocity motion of supercavitating kinetic strikers in water. To investigate the stressed-strained state and a possible destruction of solid bodies during the motion in water and in interaction with underwater barriers of various types, the authors carry out mathematical modeling based on a unified methodological approach of the continuum mechanics. The range of the velocities under study is 500-1590 m/s. Results of the group start of supercavitating strikers are given. [ABSTRACT FROM AUTHOR]

We consider the possibility of obtaining composites with increased mechanical strength resistant to high-velocity impact by means of self-propagating high-temperature synthesis (SHS) of metal-ceramic materials with graded composition-in particular, of layered type. A two-layer combined metal-ceramic material has been developed comprising NiTi-bonded titanium diboride (TiB2) layer on a metallic titanium substrate layer. The impact resistance of this composite is advantageous to that of a homogeneous titanium plate, which is manifested by the absence of a spall crater upon the impact of a spherical steel projectile and by stronger deformation and prefracture cracking of the projectile. [ABSTRACT FROM AUTHOR]