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Results of spectroscopic measurements of the equilibrium electron concentration behind a strong shock wave in argon at a shock-wave velocity of 4.2 km/s and a pressure ahead of the wave front of 5 Torr and in O2, N2, and air in the velocity range from 8.3 to 11.3 km/s at an initial pressure of 0.25 Torr are presented. The measurement method was based on an analysis of broadening of the hydrogen-atom Hβ line of the Balmer series in the spectrum of the integral radiation density of the studied gas to which a small amount of H2 was added (~1%). The dependence of the electron concentration on the shock-wave velocity in O2, N2, and air was established. The results were compared with available experimental and calculated data. [ABSTRACT FROM AUTHOR]

A technique for modeling the radiation of shock-heated oxygen by the direct simulation Monte Carlo (DSM) method is described, taking into account the rates of chemical reactions and excitation of vibrational, rotational, and electronic degrees of freedom of oxygen molecules. The simulation results are compared with the experimental data on the measurement of the radiation of shock-heated oxygen in the shock tube of the Institute of Mechanics of Moscow State University. [ABSTRACT FROM AUTHOR]

The results of modeling the radiation characteristics of the air behind the front of a strong shock wave, performed using the direct simulation Monte Carlo method, are presented. The model used takes into account various physical and chemical processes occurring in shock-heated air, including the translational-rotational and translational-vibrational energy exchange, kinetics of chemical reactions, and excitation of electronic levels of atoms and molecules, as well as the emission and absorption processes for a discrete spectrum. As a result of the calculations, time-integrated spectrograms of the volumetric radiation power of shock-heated air are obtained in absolute units in the range of shock wave velocities from 7.4 to 10.7 km/s at a gas pressure in front of the shock wave front of 0.25 Torr. The calculation data are compared with the experimental data obtained on a DDST-M double-diaphragm shock tube of the Institute of Mechanics of Moscow State University. [ABSTRACT FROM AUTHOR]

The self-ignition of a propylene–oxygen–argon stoichiometric mixture with a volumetric argon content of 95% is studied. The experiments are performed on a shock tube, which is part of the Shock Tube Experimental Complex of the Institute of Mechanics of Moscow State University, in conditions behind the reflected shock wave. The time dependencies of signals from a piezoelectric pressure sensor, a thermoelectric detector, and an optical section configured to record the radiation of electronically excited radicals OH• (λ = 302 nm), CH• (λ = 427 nm, and molecular carbon (λ = 553 nm) are analyzed. The ignition delay times τign are measured in the temperature range T = 1200–2460 K and pressures p = 4.5–25 atm. The data obtained are compared with the results of other authors. [ABSTRACT FROM AUTHOR]

The current state of research on measuring the electron concentration in low-temperature plasma in the vicinity of a strong shock wave, which simulates the conditions of the descend spacecraft entry into the Earth's atmosphere, is considered. Various physicochemical processes leading to the formation of low-temperature plasma both ahead of the shock wave front and in the shock-heated gas are analyzed. A critical review of various plasma diagnostic methods is made, and their advantages and disadvantages are noted. Numerous experimental data on measuring the electron concentration in various shock-heated gases in various conditions are analyzed. [ABSTRACT FROM AUTHOR]

An extended version of the previously developed computational procedure SPECTRUM is presented, which allows us to calculate the radiation characteristics of a shock-heated gas, taking into account the decrease in the radiation intensity in an absorbing medium. The procedure is based on a line-by-line calculation of the emission and absorption spectra of the atoms and molecules that make up the studied gas mixture. When calculating the emission spectra of atoms and molecules, the values of spectroscopic constants are taken from well-known databases. The results of calculating the time-integrated spectral characteristics of shock-heated air are compared with the available experimental data obtained in the ultraviolet, visible, and infrared regions of the spectrum. [ABSTRACT FROM AUTHOR]

A series of probe measurements to determine the electron concentration in the gas ahead of a strong shock wave (SW) front are carried out using a modified double-diaphragm shock tube (DDST-M) of the Institute of Mechanics, Moscow State University. At the same time, the light flux from the region of the shock-heated gas is recorded, which makes it possible to calculate the electron concentration behind the SW using the spectroscopic method. The experiments are carried out in air, oxygen, and nitrogen at SW velocities ranging from 8.3 to 11.3 km/s and an initial pressure of 0.25 Torr in the low-pressure chamber (LPC). The dependencies of the electron concentration on the SW velocity and the distance from the observation point to the SW are obtained. The spectroscopic measurements make it possible to determine the dependence of the electron concentration on the composition of the gaseous medium. The obtained data are compared with the experimental data of other authors. [ABSTRACT FROM AUTHOR]

Consideration has been given to the current status of research on the development of kinetic models of combustion of kerosene and its components. Surrogate models of kerosene have been analyzed that describe the physical and chemical properties of an actual fuel and are used in developing detailed and reduced kinetic models. Experimental data have been reviewed based on which testing of the kinetic models with a varying degree of complexity is carried out. Examples of the use of kinetic models in modeling numerically processes occurring in actual power-generating units have been given. [ABSTRACT FROM AUTHOR]

Composites based on indium oxide containing different amounts of zinc oxide are synthesized by hydrothermal and impregnation methods. The phase composition, structure, and specific surface of the obtained composites are studied by various physicochemical methods. The electrophysical properties of composites synthesized by different methods are compared. It is shown that the method of formation has a significant effect on the structural characteristics of the composites, which in turn leads to the implementation of various conduction mechanisms. [ABSTRACT FROM AUTHOR]

A model for the numerical study of radiation behind the front of a strong shock wave in a CO2-N2 gas mixture is proposed. The model is based on the direct statistical simulation Monte Carlo method and takes into account the physicochemical properties of atoms and molecules, translational-rotational and translational-vibrational energy transfer, kinetics of chemical reactions, excitation of electronic levels of atoms and molecules, as well as the processes of radiative energy transfer. A series of calculations of the spectral characteristics of a shock-heated mixture has been carried out. The results obtained are compared with the available experimental data. [ABSTRACT FROM AUTHOR]

The paper presents the results of studies with the use of shock tubes at the Institute of Mechanics of the M. V. Lomonosov Moscow State University, in which measurements were made of the radiation of shock-heated gases simulating the conditions of the entry of spacecraft into the atmosphere of the Earth and other planets of the Solar system with orbital and superorbital velocities. A description of the measuring equipment is given, as well as techniques of diagnostics and processing of the obtained spectroscopic information. Numerous experimental data on the radiation of shock-heated gases in a wide range of the radiation spectrum from vacuum ultraviolet to infrared have been analyzed, which serve as the basis for the development of various gas-dynamical models. [ABSTRACT FROM AUTHOR]

The integral and temporal spectral characteristics of shock-heated air are measured in the shock wave velocity range from 7.35 to 10.4 km/s at the pressure ahead of the shock front p0 = 0.25 Torr. The experiments are carried out on the DDST-M shock-wave setup of the Institute of Mechanics of Moscow State University. The radiation wave range λ = 600–1100 nm is studied; it corresponds to the visible and near infrared spectral ranges, where the main contribution to the radiation is made by the atomic lines of nitrogen and oxygen. The integral-in-time radiation spectrograms obtained in the experiments are analyzed. The distinctive features of the time oscillograms are defined for the most typical atomic lines of the spectrum. The measurement data are compared with the experimental data of other authors. [ABSTRACT FROM AUTHOR]

Using a double-diaphragm shock tube DDST-M of the Institute of Mechanics, Moscow State University, a series of probe measurements of the low-temperature plasma parameters ahead the front of an incident shock wave (SW) are carried out. Nitrogen, oxygen, air, and argon are used as the working gases. The results obtained make it possible to describe the processes of the photoelectric effect and photoionization of the gas particles due to the hard radiation of a shock-heated medium and to evaluate the effect of these processes on the change in the probe potential. The probe measurements are synchronized with the registration of the light flux, using an avalanche photodiode (PD) and a 9-frame K011 video camera located at the end of the shock tube. Data from the camera and piezoelectric sensors record the dynamics of the opening of the diaphragm and the process of the formation of an SW in the studied gas. [ABSTRACT FROM AUTHOR]

The results of measuring the integral and temporal spectral characteristics of shock-heated air are presented. The experiments are carried out on a modified two-sections SST-M shock tube of the Institute of Mechanics, Moscow State University in shock wave velocities ranging from 7.8 to 10.7 km/s and initial pressures in the low-pressure chamber of 0.125 and 0.25 Torr. The radiation wavelength range 115–195 nm, corresponding to the vacuum ultraviolet (VUV) spectral region, in which the main contribution to the radiation is made by the atomic lines of nitrogen and oxygen, is studied. The obtained radiation spectrograms are analyzed. The measurement data are compared with the available experimental data of other authors. [ABSTRACT FROM AUTHOR]

We describe a technique for modeling the excitation of electronic levels, bremsstrahlung, and photoionization in the Monte Carlo method of direct statistical simulation. The simulation results are compared with known experimental and numerical data. [ABSTRACT FROM AUTHOR]

The current state of research on the development of kinetic models of the combustion of gasoline and its components is considered. Surrogate models of gasoline that describe the physical and chemical properties of real fuel and are used in the development of detailed and reduced kinetic models are analyzed. The experimental data—based on which kinetic models of varying degrees of complexity are tested—are reviewed. Examples of the application of kinetic models in the numerical simulation of processes occurring in internal combustion engines are given. [ABSTRACT FROM AUTHOR]

Indium oxide is synthesized hydrothermally from an aqueous or alcoholic solution of indium nitrate. The phase composition and structure of the synthesized samples, as well as their conductivity and sensory response during the detection of hydrogen, are studied. A change in the conditions of hydrothermal synthesis leads to the formation of a metastable rhombohedral phase together with the main cubic phase of indium oxide. It is shown that an increase in the concentration of the rhombohedral phase in indium oxide leads to an increase in its conductivity and the maximum sensor activity for hydrogen. [ABSTRACT FROM AUTHOR]

The results of the radiation characteristics of shock-heated air measurements in the vacuum-ultraviolet region are presented. The experiments are carried out in the STS shock tube of the Institute of Mechanics, Moscow State University at shock-wave velocities of 7.3 to 10.7 km/s and initial pressures in the low-pressure chamber of 0.125, 0.2, and 0.25 Torr. An analytical model of the radiation process is constructed, which takes into account the absorption of radiation during its passage through the air. Processing the experimental dependences of the radiation intensity on time for the main radiation lines using this model made it possible to propose a radiation method for determining the electron temperature of a shock-heated gas. The presented data are compared with the experimental data of other authors. [ABSTRACT FROM AUTHOR]

The radiation characteristics of shock-heated argon are measured in the shock-wave velocity range of 4.5 to 7.8 km/s at gas pressures ahead of the shock wave front of 0.25, 1.0, and 5.0 Torr. Time-integrated sweeps of radiation and the time dependences of the radiation intensity of shock-heated argon at the wavelength of 420 nm are obtained in absolute units. The results of direct statistical simulation by the Monte Carlo method of radiation-chemical processes in the argon behind the front of a strong shock wave are presented. The model takes into account the processes of excitation and ionization of an atom by electron impact, emission and absorption for a discrete spectrum, bremsstrahlung, photoionization, and photorecombination, as well as the broadening of atomic lines. The experimental and calculated data are compared. [ABSTRACT FROM AUTHOR]

The results of a study of the pyrolysis of dried sewage sludge taken from a fixed-bed reactor of urban wastewater treatment plants are presented. The obtained experimental data made it possible to estimate the migration activity of heavy metals entering into the composition of the sewage sludge. Measurements were carried out for vanadium (V), chromium (Cr), cobalt (Co), nickel (Ni), copper (Cu), zinc (Zn), strontium (Sr), lead (Pb), rubidium (Rb), barium (Ba), zirconium (Zr), and arsenic (As). It is shown that the emission of heavy metals upon release of volatile substances during pyrolysis is characteristic for almost all of the studied elements, among which As, Rb, Co, and Ba are the elements having the highest migration activity. [ABSTRACT FROM AUTHOR]

The results of measuring the integral and temporal spectral characteristics of shock-heated air are presented. The experiments were carried out in a modified double-diaphragm shock tube DDST-M at the Institute of Mechanics of Moscow State University in the range of shock wave velocities from 7.5 to 11.4 km/s at a pressure ahead of the shock wave front p0 = 0.25 Torr. The range of radiation wavelengths λ = 190–670 nm, corresponding to the ultraviolet and visible spectral regions, in which the main contribution to the radiation is made by molecular bands, has been studied. The analysis of the obtained time-integrated radiation spectrograms is carried out. The features of the time oscillograms for the most typical molecular lines of the spectrum are underlined. The data of measurements are compared with the experimental data of other authors. [ABSTRACT FROM AUTHOR]

Using the methods of computational fluid dynamics, a comparative analysis of the stabilization of the detonation combustion of kerosene vapor in a supersonic air flow entering an expanding and convergent-divergent axisymmetric nozzle with a central body is carried out. The mathematical model is built based on unsteady two-dimensional Euler equations for the axisymmetric flow of a multicomponent reacting gas and a reduced detailed scheme of the chemical kinetics of ignition and combustion of a kerosene mixture. The calculations use a modification of the numerical scheme of S.K. Godunov of the second order of approximation of smooth solutions in space variables. The configurations of the nozzle channels which stabilize the de-tonation combustion of kerosene vapor are determined. Under conditions of the surface atmosphere, the efficiency of detonation combustion of kerosene in an expanding nozzle and a convergent-divergent nozzle is compared in terms of the specific impulse and thrust at Mach numbers of the oncoming flow of 7 and 9. [ABSTRACT FROM AUTHOR]

The data on the efficiency of chemical sensors consisting of binary mixtures of semiconducting metal oxides having different conducting and catalytic properties have been considered. The sensors exhibit a high efficiency for detecting toxic, inflammable, and explosive gases, such as hydrogen, CO, methane, ammonia, and ozone, in air. The developed sensor systems have been shown to be useful for the timely warning about the appearance of the aforementioned compounds in the atmosphere in different concentrations. [ABSTRACT FROM AUTHOR]

A comprehensive study of the two-stage thermal processing of dried sewage sludge (SS) into synthesis gas with a high hydrogen content is carried out. The data of the thermogravimetric (TG) analysis of the studied material are used to determine the kinetic parameters of its decomposition. An experimental study of the pyrolysis of dried SS in a fixed-bed reactor makes it possible to reveal the main regularities in the formation of pyrolysis products (semicoke, tar, noncondensable gas, and water). Using the data of gas chromatography-mass spectrometry, the quality of liquid pyrolysis products is assessed. It is shown that the two-stage thermochemical conversion of the initial material, which combines pyrolysis and the subsequent heterogeneous cracking of volatile pyrolysis products, makes it possible to effectively obtain a fairly pure high-calorie gas, the main components of which are hydrogen and carbon monoxide. [ABSTRACT FROM AUTHOR]

A technique for calibrating the recording system for of gas emission behind the shock wave front at the Shock Tube experimental complex of the Institute of Mechanics, Moscow State University in the spectral range 120–185 nm is presented. The presented approach makes it possible to extend the range of obtaining the experimental data to the region of vacuum ultraviolet (VUV) radiation. The study is focused on the issue of obtaining measured values in absolute units. A technique for the preliminary calibration of the measuring system using standard radiation sources is described. It is shown that the power of radiation from the VUV region can significantly exceed the value of radiation fluxes from other regions of the spectrum. [ABSTRACT FROM AUTHOR]

Results are presented of an investigation into the pyrolysis of components of a model mixture of medical waste of standard composition and of the entire mixture in a fixed-bed reactor using the methods of thermogravimetric analysis. Data on the regular patterns of chlorine redistribution between the pyrolysis products are presented. It is shown that in pyrolysis of a medical waste mixture whose composition includes chlorine-containing components, chlorine is partially released into the gaseous phase in the form of HCl and partially retained by semicoke. In this case, the degree of chlorine retention by semicoke depends on the ash content of the starting material and the composition of its mineral part. [ABSTRACT FROM AUTHOR]

A family of axisymmetric Laval nozzles with a central cylindrical part is considered. The nozzle diffuser with relatively small dimensions ensures stable detonation combustion of kerosene vapor behind an inclined shock front that forms before entering the combustion chamber without auxiliary initiating structures and additional energy supply. Modeling is carried out based on the two-dimensional unsteady Euler equations of motion for axisymmetric flows of a multicomponent gas and a simplified kinetic scheme of chemical transformations. The calculations are performed using a modified numerical scheme by S.K. Godunov of the second order of accuracy in spatial variables. It is shown that effective detonation combustion occurs on the impact of the initiating shock front on the wall of the combustion chamber in the immediate vicinity of the corner point of conjugation with the diffuser. The parameters of a number of nozzles are determined, in which the detonation combustion of kerosene vapor provides high power characteristics with an efficiency of more than 40% in atmospheric air at an altitude of about 40 km at a flight Mach number of M0 = 9. [ABSTRACT FROM AUTHOR]

The possibility of using a thermoelectric detector (TD) to measure the ignition delay time of a combustible mixture behind the front of a reflected shock wave is demonstrated. This device has already been used to record heat flows in shock tubes and is used for the first time to record the process of ignition of combustible mixtures. In the course of experiments with propane-air mixtures, it is found that the TD is capable of recording high heat flows, low inertia, high signal-to-noise ratios, and high time resolution. It is also shown that, due to the faster response time, the use of the sensor makes it possible to refine the ignition delay time of the mixture, and the sensor itself can serve as a useful device for studying the ignition processes of combustible mixtures in shock tubes in more detail. [ABSTRACT FROM AUTHOR]

The current state of research in shock tubes to measure the radiation of high-temperature gases, which simulate the conditions for the entry of spacecraft (SC) into the atmosphere of the Earth and other planets of the solar system, is considered. A critical review of various types of experimental setups is made, and their advantages and disadvantages are noted. A description of the measuring equipment and methods for diagnosing the obtained spectroscopic information is given. Numerous experimental data on the radiation of shock-heated air along the descent trajectories of SC in the Earth's atmosphere are analyzed. The radiative characteristics of shock-heated gas mixtures simulating the composition of the atmospheres of Mars, Venus, Titan, and the giant planets are also considered. [ABSTRACT FROM AUTHOR]

The emission spectra of oxygen behind the front of a strong shock wave were studied in the range of shock wave speeds of 5.7–7.4 and 8.1–10.0 km/s at pressures of 1.0 and 0.25 Torr in front of the wave front. Time-integrated sweeps of radiation over a wide spectral range of 200–675 nm and time oscillograms of oxygen radiation were obtained. Analysis of the obtained panoramic spectra shows that at low shock wave speeds the radiation spectrum is dominated by a system of Schumann–Runge molecular bands. Increase of the shock wave speed leads to the appearance of strong atomic lines in the emission spectrum. Features of the time oscillograms for the most typical lines of the spectrum (the radiation of molecular oxygen at a wavelength of 213 nm (Schumann–Runge system) and atomic oxygen at wavelengths of 394 and 645 nm) are identified. [ABSTRACT FROM AUTHOR]

The pyrolysis of medical wastes is experimentally studies in a fixed-bed pyrolysis reactor. The typical mixture consisting of carbohydrates, polyolefins, and N-, Cl-, or S-containing polymers is selected as the raw material. The pyrolysis of the mixture components is also studied by thermogravimetric analysis methods. They yield the kinetic parameters of the component decomposition. The measurements taken in a fixed-bed reactor agree closely with the results of the kinetic calculation. Analysis of the obtained data enabled us to propose the best environmentally friendly method for the thermal processing of medical waste minimizing the environmental emission of toxic chlorinated compounds. [ABSTRACT FROM AUTHOR]

The results of measuring the radiation characteristics of the shock-heated mixture of CO2–N2 simulating the atmosphere of Mars are presented. Experiments carried out on a modified double-diaphragm shock tube (DDST-M) of the Institute of Mechanics, Moscow State University for two combinations of initial pressures and velocities of the shock wave: 5.4–6.8 km/s at a pressure of 1.0 Torr and 5.3–8.1 km/s at a pressure of 0.3 Torr. Panoramic radiation spectra in the wavelength range of 200 to 850 nm (ultraviolet and visible spectral ranges) and the temporal dependence of the radiation intensity of one of the most intense emission bands were obtained. The measurement data are compared with the experimental data of other authors. [ABSTRACT FROM AUTHOR]

An upgraded double-diaphragm shock (DDST-M) tube with detonation initiation of strong shock waves (SWs) for producing conditions simulating the entry of spacecraft (SC) into the Earth's atmosphere at the second cosmic velocity is described. The result is achieved by optimizing the combustion of the hydrogen–oxygen mixture in the high-pressure chamber by installing a special perforated disk at the end wall of the chamber. Injection of hot gas jets through the disk openings ensures the rapid formation of a turbulent flame and a leading SW, the reflection of which from the diaphragm provides gas combustion in the energetically efficient Chapman–Jouguet detonation mode. The radiation intensities of shock-heated air in the ultraviolet and visible spectral regions are measured at a SW velocity of 11.4 km/s and an initial gas pressure ahead of the SW of 33.25 Pa. [ABSTRACT FROM AUTHOR]

The relationship between the structure and properties of nanoscale conductometric sensors based on binary mixtures of metal oxides in the detection of reducing gases in the environment is considered. The sensory effect in such systems is determined by the chemisorption of oxygen molecules and the detected gas on the surface of metal oxide catalytically active particles, the transfer of the reaction products to electron-rich nanoparticles, and subsequent reactions. Particular attention is paid to the doping of nanoparticles of the sensitive layer. In particular, the effect of doping on the concentration of oxygen vacancies, the activity of oxygen centers, and the adsorption properties of nanoparticles is discussed. In addition, the role of heterogeneous contacts is analyzed. [ABSTRACT FROM AUTHOR]

The results of measuring the radiation characteristics of the shock-heated mixture of CO2–N2 simulating the atmosphere of Mars are presented. Experiments carried out on a modified double-diaphragm shock tube (DDST-M) of the Institute of Mechanics, Moscow State University for two combinations of initial pressures and velocities of the shock wave: 5.4–6.8 km/s at a pressure of 1.0 Torr and 5.3–8.1 km/s at a pressure of 0.3 Torr. Panoramic radiation spectra in the wavelength range of 200 to 850 nm (ultraviolet and visible spectral ranges) and the temporal dependence of the radiation intensity of one of the most intense emission bands were obtained. The measurement data are compared with the experimental data of other authors. [ABSTRACT FROM AUTHOR]

An upgraded double-diaphragm shock (DDST-M) tube with detonation initiation of strong shock waves (SWs) for producing conditions simulating the entry of spacecraft (SC) into the Earth's atmosphere at the second cosmic velocity is described. The result is achieved by optimizing the combustion of the hydrogen–oxygen mixture in the high-pressure chamber by installing a special perforated disk at the end wall of the chamber. Injection of hot gas jets through the disk openings ensures the rapid formation of a turbulent flame and a leading SW, the reflection of which from the diaphragm provides gas combustion in the energetically efficient Chapman–Jouguet detonation mode. The radiation intensities of shock-heated air in the ultraviolet and visible spectral regions are measured at a SW velocity of 11.4 km/s and an initial gas pressure ahead of the SW of 33.25 Pa. [ABSTRACT FROM AUTHOR]

The relationship between the structure and properties of nanoscale conductometric sensors based on binary mixtures of metal oxides in the detection of reducing gases in the environment is considered. The sensory effect in such systems is determined by the chemisorption of oxygen molecules and the detected gas on the surface of metal oxide catalytically active particles, the transfer of the reaction products to electron-rich nanoparticles, and subsequent reactions. Particular attention is paid to the doping of nanoparticles of the sensitive layer. In particular, the effect of doping on the concentration of oxygen vacancies, the activity of oxygen centers, and the adsorption properties of nanoparticles is discussed. In addition, the role of heterogeneous contacts is analyzed. [ABSTRACT FROM AUTHOR]

The relationship between the structure and properties of nanoscale conductometric sensors based on binary mixtures of metal oxides in the detection of reducing gases in the environment is considered. The sensory effect in such systems is determined by the chemisorption of oxygen molecules and the detected gas on the surface of metal oxide catalytically active particles, the transfer of the reaction products to electron-rich nanoparticles, and subsequent reactions. Particular attention is paid to the doping of nanoparticles of the sensitive layer. In particular, the effect of doping on the concentration of oxygen vacancies, the activity of oxygen centers, and the adsorption properties of nanoparticles is discussed. In addition, the role of heterogeneous contacts is analyzed. [ABSTRACT FROM AUTHOR]

The ignition delay times are measured in propane–oxygenl mixtures strongly diluted with argon. The experiments are carried out in a shock tube behind the front of the reflected shock wave in the temperature range T = 1250–1770 K at pressure p = 30 atm and the following values of the excess fuel ratios: ϕ = 0.5, 1.0, and 2.0. It is shown that, in the region of the studied temperatures, the ignition delay time in propane increases with an increase in ϕ. The obtained data are compared with the results of other measurements, which shows that at low temperatures (T ≤ 1000 K) the dependence of the ignition delay time on ϕ has the opposite character. [ABSTRACT FROM AUTHOR]

The possibility of stabilizing the detonation combustion of kerosene and gasoline vapors in a supersonic air flow entering an axisymmetric convergent–divergent nozzle with a central body under atmospheric conditions at an altitude of 16 km is studied numerically. The central body provides direct initiation of detonation due to the thermal and kinetic energy of the incident flow. The mathematical model is based on two-dimensional unsteady Euler equations for an axisymmetric flow of a multicomponent reacting gas and reduced kinetic models of combustion of flammable mixtures. The calculations use a modification of the numerical scheme of S.K. Godunov of the second order of accuracy in spatial variables. The central body of the cylinder–cone (CC) and cone–cylinder–cone (CCC) types is considered. The possibility of stabilizing the detonation combustion of kerosene at the oncoming flow of Mach numbers of M = 7 and 9 with thrust generation is shown. In the case of gasoline, only a small part of the mixture burns in the detonation mode behind the detached shock wave in front of the end wall of the central body. The thrust obtained in gasoline vapors does not compensate the aerodynamic resistance of the nozzle and the central body. [ABSTRACT FROM AUTHOR]

A method for calibrating the system for recording the gas emission behind the front of a shock wave at the Shock Tube Experimental Complex of the Research Institute of Mechanics of Moscow State University in the spectral range 190–1100 nm is presented. The primary attention is paid to the issue of obtaining measured values in absolute units. The procedure for calibrating the measuring system using standard radiation sources is described. It is shown that only the combined use of the panoramic spectrum data with the results of the temporal evolution of radiation in a narrow spectral range makes it possible to obtain the correct information on the radiation power density of the plasma components in a shock wave. [ABSTRACT FROM AUTHOR]

A new simplified kinetic model of kerosene combustion, which can be included in the complex modeling of various gas-dynamic flows, is developed. The model is based on the use of n-decane as a substitute for kerosene and contains 24 components that are involved in 25 chemical reactions describing the ignition of kerosene at both high and low temperatures. The proposed model is tested by comparing the calculation results with the available experimental data on measuring the ignition delay time in shock tubes in a wide range of temperatures and pressures. [ABSTRACT FROM AUTHOR]

An experimental investigation has been conducted into the pyrolysis of typical medical waste components in a fixed-bed reactor with a view to obtaining detailed information on the process characteristics. It is shown that the main loss of the mass of the mixture of chlorine-containing medical wastes occurs in two stages. The first stage which finishes at a temperature of about 400°C is characterized by the discharge of pyrolysis water and gas which contains hydrogen chlorine. At the second stage, at a temperature from 400 to 500°C, there is a discharge of the main part of volatile substances that are largely made up of pyrolytic oil. An environmentally safe and cost-effective method of solving the problem of medical waste disposal based on its two-stage pyrolysis has been proposed. The method includes the removal of chlorine-containing components from medical waste before the thermal degradation of their organic part, which, in practice, excludes the possibility of formation of highly toxic chlorine-containing substances. [ABSTRACT FROM AUTHOR]

Emission spectra of argon behind the front of a strong shock wave are studied in the range of shock-wave velocities of 4.6–8.3 km/s and pressures before the wave front of 0.25–5.00 Torr. Time-integrated sweeps of radiation in a wide spectral range from the ultraviolet to infrared (190–1100 nm) and time dependences of the argon radiation intensity at wavelengths of 420, 532.8, and 740 nm are obtained. Three characteristic stages of the temporal evolution of the emission lines are defined. The dependences of the duration and intensity of the emission lines on the initial gas pressure and shock-wave velocity are established. Data are obtained on the background radiation intensity and can be used to separate the intensities of certain argon-atom lines from the total radiation. [ABSTRACT FROM AUTHOR]

Experimental data on the ignition delay times in a stoichiometric propane-air mixture have been obtained. The experiments were carried out on a shock tube in a temperature range of 1065–1595 K behind the front of the reflected shock wave at pressures of 23–33 atm. A comparison of the obtained data with the results of other measurements and the data from kinetic calculations is presented. [ABSTRACT FROM AUTHOR]

The results of studies on the application of pyrolytic methods for the processing of solid municipal waste into liquid and gaseous fuels are presented. The features and types of pyrolytic processes are reviewed, and the key pyrolytic products are analyzed in detail with respect to the process pressure and heating rate of the initial mass of solid municipal waste. Since the liquid products produced with standard pyrolysis have a high content of oxygen-rich compounds and water, catalytic methods are employed to make high-quality boiler or transport fuels. The main types of catalysts, their properties, and their effects on the process are considered. The advantages of a two-stage process, in which the pyrolytic products at the second stage of the process undergo high-temperature catalytic cracking with the formation of synthesis gas (syngas), are analyzed. [ABSTRACT FROM AUTHOR]

The purification of aqueous solutions containing, together with the salts of heavy metals (lead and copper), sodium and calcium salts are studied. It is shown that cleaning with the use of AK-2 cation-exchange resin leads to the removal of only sodium and calcium salts from the solution. Cleaning with sorbents based on crown ethers also does not provide the complete removal of heavy metal ions from solutions. Almost the complete removal of all salts from solutions is achieved using a two-stage purification: first, the solutions are passed through the AK-2 resin and then treated with sorbents based on crown ethers. [ABSTRACT FROM AUTHOR]

The experimental data on methods for the preparation of sorbent systems containing crown ethers and their complexing properties with cations of some radioactive and heavy metals were summarized and analyzed. The sorbents in which crown ethers are covalently bonded with the organic or inorganic substrate were shown to be more stable in the treatment of municipal and industrial wastewater from radionuclides and heavy metals. The key factor that determines the efficiency of cation adsorption by crown ether is the fit between the cation size and the cavity diameter of the crown ether. [ABSTRACT FROM AUTHOR]

The sorption of copper and lead ions by sorbents based on 15-crown-5 and 18-crown-6 esters and their benzosubstituted analogs chemically bonded to porous mineral substrates under the action of gamma radiation is considered. The influence of various parameters on the efficiency of metal sorption from aqueous solutions is studied. The correspondence between the ability of the sorbent to absorb metal ions and the size of the cavity of the crown ether (CE) is shown, which determines the high level of selectivity of such sorbents. Indeed, sorbents based on 18-crown-6 ether have a significantly higher sorption capacity in relation to lead, while 15-crown-5 ether is more effective for the sorption of copper ions. The effect of the radiation dose rate and the time of holding the sorbent in a salt solution on the amount of sorbed metal is studied. [ABSTRACT FROM AUTHOR]

A software package consisting of the TETRAN-PRO and the COND-KINET-1 proprietary computer codes, as well as computational methods and models they are based on, is described. The TETRAN-PRO code calculates the composition and thermodynamic properties of a multicomponent reacting system under thermodynamic equilibrium conditions, including products of combustion or pyrolysis of organic and composite fuels. The difference of this code from similar ones is the use of the method of prevailing components, which is most effective as to convergence, computation time, and the range of parameters used. The code includes the necessary database of the original thermodynamic properties for 3000 individual substances. The TETRAN-PRO code's capabilities are demonstrated by the results from calculation of mercury vapors' conversion in the combustion products of Kuznetsk and Berezovo coals. The COND-KINET-1 calculates the parameters of a condensation aerosol formed during the bulk condensation in a vapor-gas mixture flow. The process is described with a system of moment equations for the droplet size distribution function, which is closed by the equations of momentum and energy. A comprehensive approach, thermodynamic and kinetic, has been formulated to the description of the bulk condensation in multicomponent reacting systems based on the TETRAN-PRO and COND-KINET-1 codes. The approach's capabilities are demonstrated by the example of numerically simulating the formation of environmentally dangerous submicron particles in burning coals according to the condensation mechanism. Data on the concentration and size distribution of the generated particles are obtained. The predicted data on the fractional composition of particles are compared with the experiment. [ABSTRACT FROM AUTHOR]