The applicability of the calibration method for heat flux sensors based on anisotropic bismuth thermoelements and a heterogeneous copper-nickel structure using a reflected shock wave to determine the volt-watt coefficient is demonstrated. The coefficient obtained for a sensor based on anisotropic thermoelements is close to the stationary calibration data, and for a sensor based on a heterogeneous structure, to the results of numerical simulation. Keywords: heat flux, calibration, shock tube, shock wave, ghfs, hghfs.

We present the results of measuring the heat flux using sensors based on anisotropic thermoelements and a thin-film resistance sensor for cases of shock-wave reflection from the end of a shock tube and an external supersonic gas flow around the model. The obtained data demonstrate that such sensors can be applied in gas-dynamics experiments in a wide range of characteristic times.

In this work, we studied the process of formation of spherical metal particles by plasma atomization of a metal cathode when it comes into contact with a liquid anode. The resulting spherical particles are geometrically suitable for additive technologies and other technical applications.

The applicability of the calibration method for heat flux sensors based on anisotropic bismuth thermoelements and a heterogeneous copper-nickel structure using a reflected shock wave to determine the volt-watt coefficient is demonstrated. The coefficient obtained for a sensor based on anisotropic thermoelements is close to the stationary calibration data, and for a sensor based on a heterogeneous structure, to the results of numerical simulation.

An analysis of main features of unsteady heat flux measuring in shock tubes experiments with a characteristic process time of ~1 μs - 1 ms using sensors based on anisotropic bismuth thermoelements is made. The heat flux behind the reflected shock wave and at the blunt body stagnation point has been measured. Testing of the heat flux calculation method was carried out. The difference between the experimental data and the theoretical value of the heat flux does not exceed 50%. The possible reasons influencing the magnitude of measurement uncertainty are analyzed. The experiments performed have shown the applicability of a sensor based on anisotropic thermoelements and the method for calculating the heat flux from its electrical signal for typical conditions of experiments on shock tubes.

The features of 3D printing method for rapid prototyping and manufacturing of models for a pulsed high-speed gas-dynamic experiment are considered. Modern additive technologies allow the production of models. The basic properties of the materials and the advantages of 3D printing methods are described. The structure and properties of the obtained models can be unattainable using traditional manufacturing techniques. The design of the wind tunnel nozzle block is considered, which provides for the production of profiled contours using 3D printing. The advantages and disadvantages of use of such units on the shock tube are considered.

Experimental investigations of the emission spectrum of a CaO molecule behind the front of a reflected shock wave on a 50 mm diameter shock tube at the Ioffe Institute are carried out. The spectra were obtained using a compact spectrometer, as well as using a spectrometer based on an upgraded MDR-12 monochromator and a Sony SLT-A77 camera as a radiation detector. The emission spectra of CaO at different gas temperatures were obtained. The results can be used to test theoretical models of the emission spectrum of the CaO molecule at different temperatures.

The study is devoted to assessing the applicability of the manufactured thermoelectric sensor to measure pulsed heat fluxes in shock-wave processes. It is shown that the created thermoelectric sensor has fast response time and sufficient level of electric signal and can be successfully used in short duration high speed gas dynamic experiments.

The results of experimental studies of the magnetohydrodynamic (MHD) effect on the flow around an axisymmetric model of a supersonic nitrogen stream are presented. The magnetic field was created by a solenoid located on the cylindrical part of the model under the influence of a pulsed electric current flowing through the solenoid. A pulsed gas discharge was ignited on the conical surface of the model, acquiring rotation in the solenoidal magnetic field around the model axis. The effect of the magnetic field on the gas-dynamic structure of the flow near the model and the heat flux to its surface were investigated. In the experiments, schlieren pictures,fast photographic scans of the discharge glow were recorded, and heat flux was measured. The effect of a magnetic field on the gasdynamic structure of the flow near the model and the heat load to its surface were found. Also, the dependence of MHD effects on the polarity of external voltage source connecting was found.

Interaction of a body with an incident supersonic flow is considered. By using numerical and experimental methods, gas-dynamic parameters of the supersonic flow near the body are determined for various Mach numbers. Theoretical calculations of the supersonic flow around a body are carried. The mathematical models used in the calculations are verified by the results of experimental studies performed in the IT-1M hypersonic impulse tube of the aerodynamic laboratory of the Mozhaysky Military Space Academy.

Non-equilibrium air plasma generated in free glow discharge is characterized by optical emission spectroscopy techniques in the wavelength range of 340–440 nm. The rotational and vibrational temperature are studied as a function of distance from the electrode, to find out differences in the distribution of plasma parameters along with the discharge axis. In this work, the rotational and the vibrational temperature is determined from rovibrational spectra of second positive N 2 system. It is observed that N 2 + / N 2 intensity ratio increases from anode to cathode along the discharge axis.

The study of the interaction of conical bodies with an incident supersonic flow is carried out. In the presented theoretical and experimental studies, the parameters of the incident flow near the investigated bodies were determined at different Mach numbers. Experimental studies were carried out using a supersonic atmospheric-vacuum tube of the aerodynamic laboratory of the Mozhaysky Military Space Academy. The theoretical study is based on the model of a viscous perfect gas described by the Navier-Stokes equations.

Thermal measurements were carried out using the sensors on anisotropic thermoelements during normal shock wave reflection with Mach number M = 3 … 5. The method of processing of sensor’s electric signal has been tested at low signal / noise ratio and characteristic time ∼0.1 μs.

There is a need to improve the methods of control of supersonic aircraft in order to increase the efficiency and reliability of their control elements. In this work, theoretical calculations of the flow around a body with a system of supersonic jets are carried out. Using numerical methods, the possibility of control the flow around a body using a system of jets has been investigated. The numerical study was based on a model of an inviscid perfect gas described by the Navier-Stokes equations.

AbstractSolid polycarbonate impactors were accelerated in a channel of electromagnetic railgun to which an external pulsed magnetic field was applied. The channel was filled with air at atmospheric pressure. The dynamics of impactor acceleration in the railgun was calculated. The impactor velocities in the railgun muzzle were measured in two cases. In the first case the railgun and external field system were powered from independent energy sources (scheme 1) and in the second case the railgun and external field circuits were connected in series to a common energy source (scheme 2). It was established that the effective coefficient of rail erosion in a 2-mm caliber channel that takes into account only the eroded mass captured by the plasma piston was 1.5–1.7 mg/C, and the eroded mass involved in the motion was comparable with the impactor mass. It was shown that in scheme 1, when the external field system was switched earlier, the impactor was accelerated at a maximum magnetic induction, and the impactor velocity in the channel muzzle exceeded 6 km/s.

In this study we investigate the possibility of using plasma rail accelerator as a dense plasma jet generator for scientific and technological purposes. It was found that plasma railgun can generate supersonic plasma jets, both pure and saturated with solid and liquid microparticles. Such jets can cause thermal and mechanical erosion of the target surface, sputtering material of the railgun channel and transferring it to the surface being treated. We studied working regimes of the plasma railgun. SEM and optical micrographs of the treated samples were obtained.

The processing of the current-voltage characteristics (IVC) taken from multi-tip field emitters (LAFEs) requires a streamlined and objective processing method for obtaining the main emission parameters. This paper considers different approaches for determining the effective emission surface. Methods for determining the area are applied to the analysis of experimental IVCs for single-walled (SW) and multi-walled (MW) LAFEs. The dependence of the effective emission area on the applied voltage was confirmed.

Abstract The study of elements of rail electromagnetic accelerator (railgun), aimed at studying the mechanism of formation of the dense and free from impurities plasma jet with high kinetic energy is presented. The accelerator was tested with pulsed gas inlet, different shape and length of electrodes, as well as with an additional magnetic field created by external conductors with current. The method controlling of plasma jet parameters on test bench with the use of pressure sensor and infrared video camera was developed. The dependence of the pressure of deuterium plasma flow on distance to the accelerator was investigated. The kinetic energy of the jet was estimated.