Gas-dynamic Processes Research Articles

About One Approach to the Construction of a Solution to the Problem of Coal and Methane Emissions from the Marginal Zone of the Formation

Based on the model of the geomechanical state of a coal massif containing a coal seam with a fragile layer, a mining working and the ideas developed by S.A. Khristianovich about gas-dynamic processes in the development of coal seams, a solving of the ejection of the marginal part of the formation is constructed. The conditions for the occurrence of gas-dynamic phenomena are formulated, which manifest themselves in the form of the formation first of a main crack in a formation with free methane, then the formation of a crushing wave in it, followed by the release of a jumper and a mixture of crushed coal and gas into mine working.

Near-cathode plasma and gas-dynamic processes during the formation of a spark discharge in air at atmospheric pressure in the gap point-plane

Using the method of shadow photographing, the formation of a spark discharge in the "tip (cathode)-plane" interval with a length of 1.5 mm is investigated. Two types of shock waves have been registered cylindrical, created when the discharge channel expands, and cathode, presumably generated by cathode flares near the surface of the tip electrode. The computational and theoretical consideration of the proposed mechanism is carried out. Keywords: gas discharge, microstructure, electron temperature, degree of gas ionization.

Влияние структуры течения газа в осесимметричном канале на формирование неоднородного температурного поля в наполнителе из твердого легкоплавкого материала

This paper presents a study of the interaction between high-speed airflow and the surface of a solid low-melting material in a flowing channel of a model body. Both numerical and experimental approaches are used to solve the problem, which allows one to perform a comprehensive analysis of the processes under study. Numerical simulation conditions correspond to aerodynamic tests in the experimental facility. The unsteady Reynolds-averaged Navier-Stokes (URANS) equations are used to describe a gas flow. When solving the problem, the coupled heat-transfer and turbulence are taken into account. The low-temperature gas-dynamic processes are considered, while the chemical reactions and phase transition are neglected. As a result of numerical simulations, the flow structure and regime in a flowing channel of the model are determined, as well as the pressure and temperature distributions in the near-wall region of a solid combustible material. The gas flow regime corresponds to an underexpanded jet flow with the separation of the boundary layer and the formation of the intense heat-transfer regions at the initial section of the flowing channel. According to the numerical simulation results, in aerodynamic tests with a Mach number of 6, the melting point is attained in the near-wall region of the solid combustible material (polyethylene, polyoxymethylene, and wax). Aerodynamic tests are carried out to validate the obtained results. Experimental results show that the variation in the flowing channel diameter in the thick-wall cylinder made of polyethylene and polyoxymethylene is induced by thermal expansion. In aerodynamic tests with a wax cylinder, the mass reduction and the fusion of the solid-gas interface are revealed.

Method of numerical modeling in the problems of predicting the effect from air gap in blasthole charge design

Introduction. The article presents the results of numerical modeling of the effect made the air gap in the borehole charge design on the seismic impact of blasting, base work and the stemming ejection speed. Intensification of mining drives the need for the design of blasting operations with a gentle impact on the rock mass while maintaining the required quality of the explosion. The assessment of the major blast impact on a rock mass may include both the results of collecting statistical observational data in specific mining and technological conditions, and the results of numerical modeling of crush zone formation, seismic impact, and the speed of stemming ejection during a major blast. Numerical modeling allows not only to make a preliminary forecast, but also to conduct a series of computational experiments to select the appropriate parameters of drilling and blasting operations in order to achieve the expected effect. The position and size of the air gap in the borehole charge are considered as such a parameter Research methods. The work uses an integrated method combining analysis, scientific generalization of theoretical and experimental studies relating to air gap in borehole charges, and the use of numerical modeling tools and digital technologies in mining. To simulate the action of an air gap during an explosion with expandable and destructible rock mass walls, a software package was used, consisting of the ANSYS AUTODYN software package, which has proven itself in solving non-stationary problems of nonlinear dynamics, and the software package developed by the members of the Institute of Communications and Information Technologies of the Kyrgyz-Russian Slavic University, to assess the stress-strain state of rocks using parallel computing technology. Results. Gas-dynamic processes relating to air gap were analyzed by the method of numerical simulation; the crush zone was estimated. The simulation tool was adjusted and calibrated based on numerical simulation results comparison with the results of laboratory studies of the air gap effect in wells during an explosion in organic glass. Satisfactory convergence of the results made it possible to use this tool for modeling explosive loading in conditions close to industrial scales. Discussion. The modeling performed allows us to state that the bottom work, the reduction in the stemming ejection speed and in the seismic impact are achieved through the use of an air gap and a reduced proportion of explosive. Thus, the use of numerical simulation techniques in mining problems to solve a wide range of production problems to optimize the charge design is justified. Scope of results. The results are relevant for the problems of optimizing drilling and blasting operations in the mining industry in order to ensure a gentle effect of blast on the environment

Special features of soot formation in a standard premixed ethylene/air flame diluted with DME

This paper presents the experimental and calculated results of the investigation of soot formation in a standard premixed ethylene/air flame with the addition of 15–100% dimethyl ether. The soot volume fraction was measured using the laser light extinction method at a wavelength of 520 nm. The flame temperature versus height above the burner was measured using standard Pt-Rh thermocouples. It was experimentally shown that the addition of 15% dimethyl ether to ethylene/air flame resulted in a 20% increase of soot volume fraction. The further replacement of ethylene by 60% dimethyl ether decreased the soot volume fraction at 5 fold relatively to a pure ethylene/air flame. Kinetic modeling of soot volume fraction growth with height above the burner was carried out based on the kinetic mechanisms developed by CREСK group (http://creckmodeling.chem.polimi.it/). The calculations were carried out using open software package OpenSMOKE ++, which includes the modeling of gas-dynamic processes in the premixed laminar flame reactor. Good agreement between the experimental and calculated data was obtained. The analysis of kinetic mechanism used in this study allowed determining the peculiarity of kinetic pathways of benzene formation, which is proposed as an initial substance for soot precursor. It was found, that increase of soot concentration at 15% dimethyl ether addition to the ethylene/air flame is caused by intensification of channel of benzene formation via C3H3 recombination, which additionally produced from C3H4-p (propyne). In turn, the increase of C3H4-p concentration occurred due to reactions of acetylene with CH3 radical formed during DME decomposition. These results obtained in a standard ethylene/air flame could be used for development and validation of various kinetic mechanisms of soot formation.

A method to quantify the supersonic discharge of airbag cold gas inflators

We discuss a method to quantify the supersonic discharge of airbag cold gas inflators. Since one primary quantity of interest, the mass flow with time, is not directly measurable, a combined experimental and numerical approach was chosen. Shadowgraph and schlieren images visualize the gas dynamic process. Pressure measurements were conducted inside the inflator and downstream of the outlets in the supersonic jet. In this context, a method to measure the pressure of the flow without effects of shock reflection is presented. The temperature inside the inflator was estimated using a fast response heat flux probe and assuming different scenarios for the unknown heat transfer coefficient. Then, a numerical model of the inflator was created. The experimental results served as boundary conditions and some basic sensitivities remaining unknown from the measurements were studied to verify the numerical outcome. The numerical model was verified using experimental results. Finally, the mass flow rate was derived from the numerical model and compared to an analytical model. The method can reconstruct the temporal evolution of the mass flow discharging from the inflator, the pressure and the topology of the flow field within acceptable bounds. Furthermore, the method can deliver inflow data for subsequent airbag inflation studies.Graphical abstract

Development of foam-breaking measures after removing liquid contamination from wells and flowlines by using surface-active substances

The purpose is to consider the complications that arise during the operation of gas condensate wells, in particular, the accumulation of liquid contamination. Development of new approaches to improve the efficiency of the separation equipment performance of gas gathering and treatment systems when a multiphase flow enters. Development of a foam breaking method in a gas-liquid flow after removal of liquid contaminants from wells and flowlines using surfactants. An analysis was made of the complications that may arise when removing liquid contaminants from wells and flowlines using surfactants. Measures have been developed that will make it possible to timely prevent the ingress of foam into the separation equipment of gas gathering and treatment systems. Using computational fluid dynamics (CFD) modelling, an effective foam-breaking device was developed by supplying stable hydrocarbon condensate. A method to minimize the negative impact of foam on the operation of separation equipment after fluid removal from wells and gas condensate field flowlines using a surfactant solution was elaborated. A method for its breaking was proposed to prevent the flow of foam into the gas processing unit. This method foresees the application of the technological scheme layout for supplying a stable hydrocarbon condensate to a gas-liquid flow entering the separators of the first of separation, both the main line and the measuring line. CFD modelling was used to study the process of foam breaking by feeding hydrocarbon condensate into it. The influence of the hydrocarbon condensate supplying method on gas-dynamic processes (distribution of pressure, velocity, volumetric particles of phases), and the efficiency of foam breaking was estimated. It was established that the supply of hydrocarbon condensate from one branch pipe to the pipeline through which the foam moved did not ensure its complete breaking. To increase the efficiency of foam breaking, a device with designed four nozzles for supplying hydrocarbon condensate was developed. CFD modelling made it possible to substantiate that in this case, a pressure reduction zone appeared at the place of condensate supply. Because of a sharp change in pressure, a strong improvement in the effect of foam breaking occurred. The understanding of the regularities of foam breaking processes by hydrocarbon condensate was obtained, and the design of a device for the complete foam breaking was developed. The obtained results of laboratory studies have shown that a sharp decrease in the stability of the foam occurs under the condition of an increase in the volume of stable hydrocarbon condensate added to the studied model of mineralized formation water. Based on the results of CFD modeling, a device for breaking foam by stable hydrocarbon condensate has been worked out, the effectiveness of which will be confirmed experimentally and in field conditions. The results of the performed laboratory studies and CFD modelling allow a more reasonable approach to using various available methods and measures to prevent the ingress of foam with a gas-liquid flow into the separation equipment of gas gathering and treatment systems. This approach makes it possible to develop new effective ways and measures to prevent this complication. Based on CFD modelling, it was found that when a stable hydrocarbon condensate is supplied into a gas-liquid flow, foam breaks. A method for breaking foam in a gas-liquid flow has been developed, which is original and can be introduced in practice.

Анализ и комплексная оценка газодинамических процессов на угольных шахтах с помощью методов теории вероятности и математической статистики

Introduction. The article discusses the technical distribution system of gas-dynamic and aero-dynamic processes in coal mines, characterized by: the uniqueness of modes, linearity, dynamism, variability of parameters and variable operating conditions. An analysis and a comprehensive assessment of gas-dynamic and aero-dynamic processes in coal mines is being carried out. Research tasks: to develop a methodology for the analysis and comprehensive assessment of gas-dynamic and aerodynamic processes in coal mines using the methods of mathematical statistics and probability theory. Research objectives. Conduct an analysis of gas-dynamic and aero-dynamic processes in coal mines. Results of the research. The dynamic properties of ventilation objects in normal operation can be described by integrodifferential equations. Analysis and evaluation of experimental data on the distribution of gas-dynamic and aerodynamic processes confirmed that the technical air supply system for coal mines is a dynamic link with an inverted effect. The developed methodology for the analysis and comprehensive assessment of gas-dynamic and aerodynamic processes in coal mines using the methods of mathematical statistics and probability theory made it possible to obtain a generalized expression for the transfer functions of ventilation objects, taking into account the delay, and to describe the dynamic properties of mining sites under various ventilation modes. It has been experimentally established that the linearized dynamic characteristics of mining sites in the ventilation mode, when the transient gas-dynamic process has the form of a «burst» of methane concentration, can be described by integro-differential equations.

Gas Dynamics Processes above the Polymers Surface under Irradiation with Broadband High-Brightness Radiation in the Vacuum Ultraviolet Spectrum Region.

Obtaining new data on the gas-dynamic responses from the polymer samples (polytetrafluoroethylene, PTFE) irradiated by powerful VUV radiation from compressed plasma flows is in the focus of the present study. An erosion type magnetoplasma compressor (MPC), a type of plasma focus discharge, was used as a radiation source. The operating voltages of the MPC were between 15 and 25 kV, the maximum measured discharge current was 200 kA, and the radiation energy in the VUV range was ≈1–2 kJ. The VUV fluxes on the sample surface were high and equal to ≈1022–1024 photons cm−2·s−1. Double-exposure laser holographic interferometry and schlieren photography were used to diagnose and visualize the gas-dynamic structures. The spatial distribution of the parameters (temperature, pressure and concentrations of electrons and ions) was defined based on the assumption of local thermodynamic equilibrium. It has been demonstrated that the maximum temperature ranged from ≈ 10 to 15 kK in the plasma layer. The electron concentration was ≈ (0.7–1.6) × 1018 cm−3 in this region. The used techniques of optical diagnostics and procedures of result processing make it possible to obtain data on the dynamics of polymer ablation, which occurs when their surface is exposed to powerful energy fluxes (thermal, shock-wave, radiation, and other extreme loads).

Modeling Interfacial Interaction between Gas Molecules and Semiconductor Metal Oxides: A New View Angle on Gas Sensing.

With the development of internet of things and artificial intelligence electronics, metal oxide semiconductor (MOS)-based sensing materials have attracted increasing attention from both fundamental research and practical applications. MOS materials possess intrinsic physicochemical properties, tunable compositions, and electronic structure, and are particularly suitable for integration and miniaturization in developing chemiresistive gas sensors. During sensing processes, the dynamic gas-solid interface interactions play crucial roles in improving sensors' performance, and most studies emphasize the gas-MOS chemical reactions. Herein, from a new view angle focusing more on physical gas-solid interactions during gas sensing, basic theory overview and latest progress for the dynamic process of gas molecules including adsorption, desorption, and diffusion, are systematically summarized and elucidated. The unique electronic sensing mechanisms are also discussed from various aspects including molecular interaction models, gas diffusion mechanism, and interfacial reaction behaviors, where structure-activity relationship and diffusion behavior are overviewed in detail. Especially, the surface adsorption-desorption dynamics are discussed and evaluated, and their potential effects on sensing performance are elucidated from the gas-solid interfacial regulation perspective. Finally, the prospect for further research directions in improving gas dynamic processes in MOS gas sensors is discussed, aiming to supplement the approaches for the development of high-performance MOS gas sensors.

Застосування числових методів газодинамічних розрахунків в задачах обтікання перешкод розрідженим струминним потоком

The development of competitive space hardware calls for continuing improvements in the accuracy of simulation of gas-dynamic processes in the space vehicle vicinity. This may contribute to extending the active life of spacecraft, thus improving the economic efficiency of space activities. In particular, quite a topical problem is the simulation of the interaction of rarefied jets from the propulsion system of a spacecraft with its individual components. To solve this problem in the case of a rather high surrounding vacuum, use is made of the molecular-kinetic concept of the gas structure based on the Boltzmann equation. The aim of this paper is to overview existing methods of simulation of gas-dynamic processes near spacecraft in a rarefied gas flow with account for propulsion system jets and to choose the most promising approaches to the solution of this problem. Among the methods considered, several main lines are set off: approximate, analytical, and numerical methods. Approximate methods use physical models of jet flow, approximation of numerical results, or a combination of both approaches. Analytical methods are based on essentially simplified assumptions and are intended for a very narrow class of problems. Numerical methods are the most universal tool of theoretical study. At the same time, each numerical method has a range of application of its own. At present, the most used and promising methods are statistical simulation methods: the direct simulation Monte Carlo method (DSMCM) and the test particle method (TPM). The former splits the continuous process of molecule motion and collisions in a rarefied gas into two successive independent stages (free-molecular transfer and relaxation) at each small time step. The simulation is done by time steps and in fact reproduces a nonstationary process. The latter, the TPM, consist in a statistical successive simulation of the wandering of test particles (molecules) on the background of field ones about the cells of the computational grid. Test particles, which move within the cells of the computational area, periodically collide with the obstacle in the flow and field particles, and in doing so they gradually change both their velocity and the field characteristics. For both statistical approaches, the simulation accuracy, as can be expected, is inversely proportional to the square root of the number of tests: the number of time steps and modeling particles for the DSMCM and the number of successively simulated test particle trajectories for the TPM. This may greatly affect the possibility of attaining a desired accuracy.

Cold spray additive manufacturing of copper-based materials: Review and future directions

The cold gas dynamic spray process is a manufacturing process strategically designed for coatings. The conditions for the deposition of materials to form coatings have evolved over several decades. Copper and copper-based cold spray coatings are an interesting field for investigation, as it has substantial commercial demand and acceptance. Several important works have already been performed in this regard that shows the immense popularity of its applications in power industries. Cold gas dynamic spray, being an economic process, can produce coatings with superior quality and low oxidation. In this paper, a particular focus has been given to copper-based cold spray coatings along with their deposition parameters. The various mechanical, electrical, corrosion, and tribological properties of these copper-based cold spray coatings are commendable and economically lucrative. A good amount of experimental data has also been included in this review article to provide comprehensive information and future scope of research about copper-based cold spray coatings.

Numerical simulation of gas-dynamic processes in the centrifugal radial fan of seeding machines

Improving the efficiency of crop production, where a significant place belongs to row crops (such as corn, sunflower, soybean, sorghum, sugar beet, etc.), is inextricably linked with the introduction of energy- and resource-saving technologies to ensure quality and timely implementation of production processes. Sowing is an important technological process. To increase the speed, as a consequence, productivity and, most importantly, quality of field works, at present, precision seeding seeders with pneumatic systems with improved characteristics of vacuum generators are used. In this case, the vacuum systems of such seeders are most often based on the use of a radial centrifugal fan. Therefore, an important task is to design the fan, taking into account the matching of its parameters with the parameters of the seeder as a whole, which requires a large number of tests and checks. The use of natural models (test tables) requires considerable time and resource expenses. On the basis of numerical simulation of gas-dynamic processes there is an opportunity to significantly reduce the number of full-scale experiments, and more accurately determine the rational form of the centrifugal radial fan. The purpose of this paper is to consider the method of numerical simulation of gas dynamic processes in a centrifugal centrifugal radial fan using computer-aided design (CAD) packages. The application of computational fluid dynamics (CFD) methods to discretize the solutions of differential equations taking into account the Euler and Navier-Stokes equations. Numerical modeling of turbulence based on k-ε models, k-ω models, and shear stress transfer (SST) models. The results of calculation of three-dimensional field of velocities and pressures in the fan working zone are presented, the rational geometrical characteristics and aerodynamic characteristics (dependence of pressure drop on the air consumption) are determined. Such approach to centrifugal fan design allows to unify significantly its parameters at the stage of development and to reduce the terms of new projects.

The Adaptive Composite Block-Structured Grid Calculation of the Gas-Dynamic Characteristics of an Aircraft Moving in a Gas Environment

This paper considers the problem associated with the numerical simulation of the interaction between the cocurrent stream occurring near a monoblock moving in the gas medium and solid fuel combustion products flowing from a solid fuel rocket engine (SFRE). The peculiarity of the approach used is the description of gas-dynamic processes inside the combustion chamber, in the nozzle block, and the down jet based on a single calculation methodology. In the formulated numerical methodology, the calculation of gas-dynamic parameters is based on the solution of unsteady Navier–Stokes equations and the application of a hybrid computational grid. A hybrid block-structured computational grid makes it possible to calculate gas flow near bodies of complex geometric shapes. The simulation of the main phase of interaction, corresponding to the stationary mode of rocket flight in the Earth’s atmosphere, has been carried out. A conjugated simulation of the internal ballistics of SFRE and interaction of combustion products jets is conducted.

Method for determining and refining the interval of data collection of gas-dynamic processes by safety criterion

To solve the problems of controlling the gas-dynamic processes of production areas and air distribution in the ventilation network, their mathematical description is required, which can be obtained only on the basis of a detailed study and determination of the parameters and characteristics of gas-dynamic processes and regularities of air distribution. The mathematical description of the production ventilation system is complicated by the fact that the variables that determine the state of the control system are random functions of time. Therefore, the main attention should be paid to determining the probabilities of the characteristics of aerogasdynamic processes. The mathematical description of the ventilation of the production area into static and dynamic characteristics was the basis for the development of an optimal control algorithm for the production area. The control algorithm for the ventilation of the mining area consists of subalgorithms for controlling the parameters of the mine atmosphere, primary processing of the received information, and generating control actions. Their development is possible on the basis of research and mathematical description of gas-dynamic processes and methods for controlling the parameters of the mine atmosphere. Effective control of gas-dynamic processes in production areas is possible only when considering the entire ventilation system, due to the interconnectedness of aerodynamic parameters. The task of optimal air distribution control in the network is to ensure the required airflow rates for ventilation, determined as a result of solving the first problem with minimal energy costs for ventilation.

Three-color pyrometry study of radiation and gas dynamic processes in a heterogeneous plasma-vortex ring

The paper presents the results of a study of a heterogeneous plasma vortex ring using the three-color image pyrometry technique. The vortex ring is formed during deceleration of a supersonic pulsed aluminum plasma jet in atmospheric air. A technique for calibrating a digital camera and a post-processing process for images are proposed that makes it possible to visualize the internal structure of the vortex. As a result of the study, the effect of vortex separation of condensed and gas flow components was experimentally demonstrated.

Gasdynamic and strength improvement of the axial flow turbine of a helicopter gas turbine engine

The article presents the results of the development of proposals to increase the safety margin of the blades and the efficiency of a single-stage axial flow turbine compressor of a small-sized turbo-shaft engine being modernized with the use of multidiscipline optimization methods. Analysis of the initial version of the turbine showed that the margin of safety of the working blades is significantly lower than that required by the strength standards. To eliminate the problem encountered the task of blade development was initially solved only according to strength characteristics, without taking into account gas dynamic processes. As a result, the geometry of the working blades that met the strength requirements was obtained. It was used as a starting point for solving the joint task of optimizing the blading, taking into account gas dynamic and deformation processes. As a result of joint optimization, a turbine version meeting the strength standards was obtained, although we had to slightly reduce the efficiency of the turbine by 0,2%.

Developing measures to eliminate of hydrate formation in underground gas storages

The objective of this article is the analysys of methods for preventing and eliminating hydrates formations, classifying them and choosing the best ones for use in underground gas storage facilities. Comprehensive measures for the stable operation of gas storage facilities in the presence of conditions for the occurrence of hydrates formations were developed. Zones, being potentially prone to the hydrates formation during the gas storage facilities operation were identified. The operational parameters of gas storage wells during gas withdrawal are analyzed. The identified wells were operated under difficult conditions due to the deposition of hydrates on the wellheads, in flowlines and process equipment of gas storage facilities. The places of the highest hydrates accumulation on underground gas storages were determined: from the bottomhole of wells to the gas purification unit of the gas gathering station. Hydrate-prone zones were identified by computational fluid dynamic (CFD) modeling at the location of regulating choke installations in underground gas storage facilities. The zones of the greatest hydrates accumulation on underground gas storages were determined: from the bottomhole of wells to the gas purification unit of the gas gathering station. The analysis of the methods used in gas storage facilities of Ukraine to prevent and eliminate hydrates formation was out. A set of measures was proposed to prevent the hydrates formation in storage facilities to ensure their stable operation. Based on the Euler approach (Mixture model) by CFD modeling, zones prone to hydrates formation were determined at the installation site of regulating chokes in underground gas storages. The influence of the degree of fittings opening on the location of potential zones prone to hydrates formation was estimated. The gas-dynamic processes in the internal cavity of the gas pipeline at the installation site of the control fittings were studied and their influence on the distribution of bulk particles of the gaseous and liquid phases was established. Based on the studies performed, it was recommended to change periodically the mode of well operation for a certain time by opening or closing the regulating choke under favorable conditions for the formation of hydrates, especially at low ambient temperatures. The obtained results of experimental studies and calculations showed that in order to solve the problem of hydrates formation at gas storage facilities, it is advisable to use diverse measures through the introduction of modern intelligent systems for monitoring and controlling the technological process. Further refinement of the algorithm of the proposed monitoring and control system with its approbation in production was provided. The results of the experimental studies and CFD modeling carried out allowed providing a more reasonable approach to the application of various available methods and measures to prevent hydrates formation in underground gas storage facilities. This approach made it possible to develop new effective ways and measures to prevent such complication. Based on the conducted experimental studies and modeling, the major zones prone to hydrates formation in underground gas storages were determined. The developed measures will allow timely detection and prevention of hydrates formation at gas storage facilities are original.

Разработка метода анализа и оценки оптимального состояния аэрогазодинамических процессов на угольных шахтах

The article deals with the state of aerogasdynamic processes in coal mines. With centralized automatic control and management of mine ventilation using a control system, in the circuit of which application software is used, the choice of a rational period for collecting information received from controlled objects is of great importance.The object of automatic control in a coal mine are the parameters characterizing the state of the mine atmosphere - methane concentration, air flow, temperature and parameters of the ventilation network (depression and aerodynamic resistance). All controlled parameters characterize the state of the atmosphere. Research goal. The purpose of the research is to develop a method for analyzing and evaluating the optimal state of aerogasdynamic processes in coal mines. Research objectives. Conduct an analysis of the optimal state of aero- gasdynamic processes and adapt the method at coal industry enterprises. Research results. Studies have been carried out on the duration of the observation interval for the modes of movement of air and gas through the goaf and bottom-hole space of the production area, to ensure the specified accuracy in determining the values for the implementation of non-stationary gas-dynamic processes. It is determined that the resulting systems of equations describing the unsteady modes of air and gas movement through the mined-out and bottom-hole space of the mining area from the standpoint of hydrodynamics with subsequent simplification of these equations based on the assumptions made. Using the results of the experiments, for the process of methane concentration, a realization length of 1 day was chosen, since during this time at least one complete production cycle has time to complete in the longwall. The duration of this cycle significantly exceeds the value of the maximum measurement interval ∆tβ = 30 min., for which it is still advisable in practice to determine the modes of movement of air and gas through the mined-out and bottom-hole space of the production area. The research results are recommended for use in the design of efficient air supply schemes in the mining areas of coal mines and the correct placement of regulators to take into account the concentration of methane in the flow of consumed air.

Justifying calculations of people warning and evacuation algorithms in case of fire in accordance with its source location variants and combustion development dynamic

Modern warning and people evacuation management systems in case of fire are able to implement different notification options (with a start evacuation delay) and different people groups routing, which reduces their flows density and the critical congestions formation probability on the evacuation routes. For these systems potential technical capabilities practical realization, warning and evacuation algorithms are required in accordance with the fire source location, the combustion development dynamic, the characteristic parameters of the object and the evacuating people. Such algorithms generation is possible on the basis of information about the current values and fire hazards increase dynamic in the premises and on the evacuation routes. The necessary information can be obtained as a result of numerical studies using software tools that implement mathematical models of heat and mass transfer and gas dynamic processes, as well as the evacuating people flows movement processes in case of fire. One of the algorithms examples for alerting and evacuating people for the educational institution building is presented. The calculated data make it possible to predict and evaluate the people safe evacuation fundamental possibility in case of fire and to propose space-planning, technical and organizational solutions and measures for its successful implementation.