Natalya Fedorova - Academia.edu (original) (raw)
Papers by Natalya Fedorova
EPJ Web of Conferences
In this paper, the results of a numerical simulation of the air flow in the vicinity of a paralle... more In this paper, the results of a numerical simulation of the air flow in the vicinity of a parallelepiped fixed on a plate are presented. The 3D calculations were performed with the ANSYS Fluent software using scale-resolving DES approach. The obtained results are compared with the experimental data and with the results of the previous numerical calculation.
Paper presents results of joint experimental and numerical investigation of pulsating jet penetra... more Paper presents results of joint experimental and numerical investigation of pulsating jet penetration into still air and supersonic flow. Goal of the study is to investigate 2D Hartmann generator properties and clear up its possibilities in providing better mixing between the air and secondary (injected) gases.
New Results in Numerical and Experimental Fluid Mechanics V, 2006
Computational Fluid Dynamics 2004, Proceedings, 2006
... The computations were performed for the Mach number 2 to 8 and the results were compared to e... more ... The computations were performed for the Mach number 2 to 8 and the results were compared to experiments carried out in the blow down and hot shot wind tunnels. ... References 1. Bourdeau C., Blaize M. and Knight D.: AIAA Paper 99–0611. ...
Computational Fluid Dynamics 2004, Proceedings, 2006
Shock Waves, Vol 2, Proceedings, 2009
ABSTRACT In inlets, a boundary layer passes through a system of shock waves and expansion fans in... more ABSTRACT In inlets, a boundary layer passes through a system of shock waves and expansion fans in optional combination. These numerous interactions may lead to the boundary layer separation and cause the inlet unstart. Double ramp configuration is often used for external pre-compression. The choice of ramp angles and a distance between ramps is of great importance to provide a necessary level of pre-compression and to avoid a flow separation. The parametric computations performing within a wide range of gasdynamic and geometric parameters provide a basis for the choice of optimum configurations. But these problems demonstrate a certain level of simulation complexity connected with intricate flow structure and turbulent character of a boundary layer. Many important flow features are not well-understood even in a case of two-dimensional flow. Recent progress in using LES and DNS for modeling of SWTBLI gives us a big hope to improve the situation. But at present, these approaches seem to be too expensive for engineering applications.
28th International Symposium on Shock Waves, 2012
28th International Symposium on Shock Waves, 2012
ABSTRACT In spite of numerous investigations, no universal theory exists which describes the mech... more ABSTRACT In spite of numerous investigations, no universal theory exists which describes the mechanism of the flame stabilization at supersonic speed [1]. The supersonic combustion chamber has a complex 3D geometry that generates an intricate system of shock waves and expansion fans interacting with wall boundary layers under non-adiabatic (cold wall) flow conditions. Fuel jets supplied into the channel upstream of the combustion chamber considerably complicate the flowpicture. In a problem of flame stabilization, there are several important factors that influence the whole process, namely, the complex structure of shock waves in the combustor chamber, flow parameters in the base region of flame holder, shock waves interactions with boundary layer in a chemically reactive flows [2]. In such conditions, the prediction of possibility of fuel ignition and stabilization is an extremely challenging and complex task.
28th International Symposium on Shock Waves, 2012
ABSTRACT The study of supersonic turbulent flows in the channelswith sudden expansion (step/ cavi... more ABSTRACT The study of supersonic turbulent flows in the channelswith sudden expansion (step/ cavities) is actual task since this configuration is used for ignition and flame stabilization. Supersonic combustion is studied for many years in order to support the future hypersonic flights. It well known that it is rather difficult to get the ignition and stable combustion at supersonic speeds [1]. The flow in the supersonic combustion chamber js charachterized by a short residence time which is only a few milliseconds of magnitude. A simple geometry to generate a flameholding region in supersonic flow is a backward facing step (BFS). Flows around BFS configuration were studied for decades and many papers were published regarding fundamental flow properties [2] as well as the scramjet combustion chamber utilization [3]. The effect of step configuration (“boattailing”) on the structure of compressible base flows was investigated in a numerous papers since Hama’s work [4]. Nevertheless, the question is little studied as far as supersonic chemically reacting flows in channels are concerned.
Journal de Physique IV (Proceedings), 2002
ABSTRACT The paper focuses on numerical simulation of wave processes observed in near-wall fluidi... more ABSTRACT The paper focuses on numerical simulation of wave processes observed in near-wall fluidized layer under action of normal shock wave. The unsteady process of interaction is described for various shock wave intensities and layer densities. It is shown, that shock wave intensity increases significantly in dense-layer, and the gain factor does not depend on the Mach number of shock wave and defined only by density ratio. The regular and Mach schemes of shock reflections are observed in computations that lead to a principally distinguish scenarios of instability development in a dusty layer.
Results of numerical simulation of interaction between an oblique shock wave and a turbulent boun... more Results of numerical simulation of interaction between an oblique shock wave and a turbulent boundary layer formed in a supersonic (Mach number M = 5) flow past a flat plate are presented. The computations are performed for three cases of interaction of different intensity, which result in an attached or detached flow. Numerical results are compared with experimental data. The effect of flow turbulence and shock-wave unsteadiness on flow parameters is studied.
Calculation results of turbulent flows in the vicinity of axisymmetric configurations of the cyli... more Calculation results of turbulent flows in the vicinity of axisymmetric configurations of the cylinderflare type for Mach numbers M = 3, 5, and 7 are presented. The calculations are performed for conditions of real physical experiments. The mathematical model is based on the averaged Navier-Stokes equations supplemented by the Wilcox turbulence model. The calculated and experimental distributions of pressure on the body surface, velocity fields, and heat-transfer coefficients are compared.
An axisymmetric laminar separated flow in the vicinity of a cone-flare model is studied experimen... more An axisymmetric laminar separated flow in the vicinity of a cone-flare model is studied experimentally and numerically for a Mach number M = 6. The distributions of pressure and Stanton numbers along the model surface and velocity profiles in the region of shock wave-boundary layer interaction are measured and compared with the calculated data. The influence of the laminar-turbulent transition on flow parameters is studied numerically.
Results of numerical simulation of the shock wave passing along a dusty layer are presented; the ... more Results of numerical simulation of the shock wave passing along a dusty layer are presented; the simulation was performed under the one-temperature, one-velocity assumption. It is shown that a system of compression and expansion waves is formed inside the layer, and these waves are successively reflected from the external boundary and solid wall. Regular and irregular reflections of the leading shock wave from the solid wall with different scenarios of instability evolution on the layer edge are described. Possible mechanisms of particle lifting from the surface are described.
Computation results of plane turbulent flows in the vicinity of backward-facing steps with leewar... more Computation results of plane turbulent flows in the vicinity of backward-facing steps with leeward-face angles β = 8, 25, and 45 • for Mach numbers M ∞ = 3 and 4 are presented. The averaged Navier-Stokes equations supplemented by the Wilcox model of turbulence are used as a mathematical model. The boundary-layer equations were also used for the case of an attached flow (β = 8 • ). The computed and experimental distributions of surface pressure and skin friction, the velocity and pressure fields, and the heat-transfer coefficients are compared.
Results of an experimental and numerical study of supersonic turbulent high-enthalpy flow in a ch... more Results of an experimental and numerical study of supersonic turbulent high-enthalpy flow in a channel with cavity are reported. On the basis of wind-tunnel tests performed in the IT-302M short duration wind tunnel, data on the flow structure and on the distribution of static pressure along the model walls were obtained. These data were subsequently used to verify the numerical algorithm. In the calculations, a parametric study of the effects of Mach number, cavity configuration, and temperature factor on flow quantities was performed. It was numerically shown that variation of the above parameters leads to a transition of the flow regimes in the vicinity of the cavity.
The results of numerical modelling and experimental investigations of high-enthalpy turbulent flo... more The results of numerical modelling and experimental investigations of high-enthalpy turbulent flows in the neighborhood of 90-degree backward-facing steps at the Mach numbers M ∞ = 2−4 are presented. The experiments were conducted in the hot-shot wind tunnel IT-302M of ITAM SB RAS. The computations were carried out on the basis of the full Favres-averaged Navier ⎯ Stokes equations augmented by the Wilcox turbulence model. The temperature factor influence on the flow structure in the separated zone and temperature distributions was investigated numerically for different Mach numbers. The wall temperature is shown to affect significantly the quantity and sizes of recirculation vortices as well as the temperature distribution in the zone of flow separation and reattachment. The computational results are compared with experimental data on the pressure distribution on the model surface and the wave structure of the flow.
The results are presented for numerical modelling of two-dimensional flows with large pressure gr... more The results are presented for numerical modelling of two-dimensional flows with large pressure gradients in a wide range of freestream parameters (М = 2−4, Re 1 = 5−30⋅10 6 1/m) and the intensities of perturbing factors. Computations were performed with the use of averaged unsteady Navier ⎯ Stokes equations of a viscous heat-conducting gas. The structure of a turbulent boundary layer at its passage through a single shock and a system of shocks of different strengths, which lie at a fixed distance from one another, was investigated numerically. In the case of the boundary layer passage through a system of shocks, the influence of the first interaction on the structure and separation properties of the boundary layer behind the second shock was investigated. The presence of a preliminary shock was shown to improve the boundary layer capability to withstand separation ahead of the secondary interaction region.
Supersonic (M ∞ = 2–5) turbulent flows in the vicinity of a two-dimensional backward-facing step ... more Supersonic (M ∞ = 2–5) turbulent flows in the vicinity of a two-dimensional backward-facing step with an inclined leeward side are considered by methods of mathematical modeling. The wave structure of the flow with a varied angle of inclination of the leeward side of the step and a varied free-stream Mach number is considered. Introduction. The problem of a supersonic flow past various steps is a classical problem of aerodynamics. Steps with different angles of inclination of the leeward side are frequent elements of the surface of flying vehicles and their propulsion units. Such a configuration is used to organize and stabilize combustion in air-breathing engines. In addition, the problem of the flow past a step is intimately related to the problem of the flow in the base region and in the near wake behind a flying vehicle entering the atmosphere. A detailed review of research performed in this field in 1950s–1970s can be found in [1, 2]. The first analytical study of the flow past a 90 • backward-facing step (BFS) was performed in [3] under the assumption that there exists a streamline dividing the separation region and the external part of the flow. An alternative method of integral moments, which was proposed in [4] and which was first used to describe the flow in the vicinity of a step in [5], is based on the hypothesis that there exists a " free jet " emanating from the rib of the body and a stagnant base region providing compression necessary for flow deflection. In earlier experimental works [6, 7], the main attention was paid to measuring the static pressure in the base region, because it exerts a significant effect on the drag of the body. The wave structure of the flow was studied in later papers [8–10]. Much attention is currently paid to large-scale vortex structures developing in the mixing layer above the separation region and playing an important role in mass, momentum, and energy transfer between the recirculation zone and the external inviscid flow [11]. The base flow is studied by methods of mathematical modeling incorporating simplified models [12] and full Navier–Stokes equations [13–16]. In the present work, we consider the flow in the vicinity of a two-dimensional BFS with an inclined leeward side. The study is performed for moderate angles of inclination of the faces, which is of interest for analyzing the boattailing effect. It is known that a change in the shape of the base part of the body [preliminary expansion with a small (up to 15 •) angle] leads to an increase in pressure in the base region and, hence, to a decrease in drag of the body [17, 18]. Some configurations computed in the present work were examined experimentally in [19]; in turn, the experimental results of [19] were used for verification of computations. In [20, 21], the same flows were studied numerically with the use of the full averaged Navier–Stokes equations supplemented by various semi-empirical models of turbulence. We also computed similar configurations previously [22]. Because of restrictions caused by a small size of the computational domain and an insufficiently refined grid, however, the detailed structure of the flow was not obtained in those computations.
Homogeneous gas-phase pyrolysis of methane in a shock tube is numerically studied. The process of... more Homogeneous gas-phase pyrolysis of methane in a shock tube is numerically studied. The process of pyrolysis occurs under the action of a shock wave reflected from the end face of the tube. An inviscid one-dimensional flow and a viscous two-dimensional flow are considered. Two-dimensional computations are performed on the basis of unsteady Navier–Stokes equations. The kinetic models used are Kassel's simplified gross scheme with 4 reactions and 5 chemical components of methane transformation and a more detailed kinetic scheme with 21 reactions and 13 chemical components. The computations are performed for the Mach number of the incident shock wave equal to M = 5.5. It is shown that the temperature behind the reflected shock wave rapidly decreases because the pyrolysis reaction is endothermic. For this reason, the chemical transformations in the course of pyrolysis are terminated when the total mass concentration of ethylene and acetylene is within 15%. Additional heating of the gas is needed for deeper conversion of methane to ethylene and acetylene.
EPJ Web of Conferences
In this paper, the results of a numerical simulation of the air flow in the vicinity of a paralle... more In this paper, the results of a numerical simulation of the air flow in the vicinity of a parallelepiped fixed on a plate are presented. The 3D calculations were performed with the ANSYS Fluent software using scale-resolving DES approach. The obtained results are compared with the experimental data and with the results of the previous numerical calculation.
Paper presents results of joint experimental and numerical investigation of pulsating jet penetra... more Paper presents results of joint experimental and numerical investigation of pulsating jet penetration into still air and supersonic flow. Goal of the study is to investigate 2D Hartmann generator properties and clear up its possibilities in providing better mixing between the air and secondary (injected) gases.
New Results in Numerical and Experimental Fluid Mechanics V, 2006
Computational Fluid Dynamics 2004, Proceedings, 2006
... The computations were performed for the Mach number 2 to 8 and the results were compared to e... more ... The computations were performed for the Mach number 2 to 8 and the results were compared to experiments carried out in the blow down and hot shot wind tunnels. ... References 1. Bourdeau C., Blaize M. and Knight D.: AIAA Paper 99–0611. ...
Computational Fluid Dynamics 2004, Proceedings, 2006
Shock Waves, Vol 2, Proceedings, 2009
ABSTRACT In inlets, a boundary layer passes through a system of shock waves and expansion fans in... more ABSTRACT In inlets, a boundary layer passes through a system of shock waves and expansion fans in optional combination. These numerous interactions may lead to the boundary layer separation and cause the inlet unstart. Double ramp configuration is often used for external pre-compression. The choice of ramp angles and a distance between ramps is of great importance to provide a necessary level of pre-compression and to avoid a flow separation. The parametric computations performing within a wide range of gasdynamic and geometric parameters provide a basis for the choice of optimum configurations. But these problems demonstrate a certain level of simulation complexity connected with intricate flow structure and turbulent character of a boundary layer. Many important flow features are not well-understood even in a case of two-dimensional flow. Recent progress in using LES and DNS for modeling of SWTBLI gives us a big hope to improve the situation. But at present, these approaches seem to be too expensive for engineering applications.
28th International Symposium on Shock Waves, 2012
28th International Symposium on Shock Waves, 2012
ABSTRACT In spite of numerous investigations, no universal theory exists which describes the mech... more ABSTRACT In spite of numerous investigations, no universal theory exists which describes the mechanism of the flame stabilization at supersonic speed [1]. The supersonic combustion chamber has a complex 3D geometry that generates an intricate system of shock waves and expansion fans interacting with wall boundary layers under non-adiabatic (cold wall) flow conditions. Fuel jets supplied into the channel upstream of the combustion chamber considerably complicate the flowpicture. In a problem of flame stabilization, there are several important factors that influence the whole process, namely, the complex structure of shock waves in the combustor chamber, flow parameters in the base region of flame holder, shock waves interactions with boundary layer in a chemically reactive flows [2]. In such conditions, the prediction of possibility of fuel ignition and stabilization is an extremely challenging and complex task.
28th International Symposium on Shock Waves, 2012
ABSTRACT The study of supersonic turbulent flows in the channelswith sudden expansion (step/ cavi... more ABSTRACT The study of supersonic turbulent flows in the channelswith sudden expansion (step/ cavities) is actual task since this configuration is used for ignition and flame stabilization. Supersonic combustion is studied for many years in order to support the future hypersonic flights. It well known that it is rather difficult to get the ignition and stable combustion at supersonic speeds [1]. The flow in the supersonic combustion chamber js charachterized by a short residence time which is only a few milliseconds of magnitude. A simple geometry to generate a flameholding region in supersonic flow is a backward facing step (BFS). Flows around BFS configuration were studied for decades and many papers were published regarding fundamental flow properties [2] as well as the scramjet combustion chamber utilization [3]. The effect of step configuration (“boattailing”) on the structure of compressible base flows was investigated in a numerous papers since Hama’s work [4]. Nevertheless, the question is little studied as far as supersonic chemically reacting flows in channels are concerned.
Journal de Physique IV (Proceedings), 2002
ABSTRACT The paper focuses on numerical simulation of wave processes observed in near-wall fluidi... more ABSTRACT The paper focuses on numerical simulation of wave processes observed in near-wall fluidized layer under action of normal shock wave. The unsteady process of interaction is described for various shock wave intensities and layer densities. It is shown, that shock wave intensity increases significantly in dense-layer, and the gain factor does not depend on the Mach number of shock wave and defined only by density ratio. The regular and Mach schemes of shock reflections are observed in computations that lead to a principally distinguish scenarios of instability development in a dusty layer.
Results of numerical simulation of interaction between an oblique shock wave and a turbulent boun... more Results of numerical simulation of interaction between an oblique shock wave and a turbulent boundary layer formed in a supersonic (Mach number M = 5) flow past a flat plate are presented. The computations are performed for three cases of interaction of different intensity, which result in an attached or detached flow. Numerical results are compared with experimental data. The effect of flow turbulence and shock-wave unsteadiness on flow parameters is studied.
Calculation results of turbulent flows in the vicinity of axisymmetric configurations of the cyli... more Calculation results of turbulent flows in the vicinity of axisymmetric configurations of the cylinderflare type for Mach numbers M = 3, 5, and 7 are presented. The calculations are performed for conditions of real physical experiments. The mathematical model is based on the averaged Navier-Stokes equations supplemented by the Wilcox turbulence model. The calculated and experimental distributions of pressure on the body surface, velocity fields, and heat-transfer coefficients are compared.
An axisymmetric laminar separated flow in the vicinity of a cone-flare model is studied experimen... more An axisymmetric laminar separated flow in the vicinity of a cone-flare model is studied experimentally and numerically for a Mach number M = 6. The distributions of pressure and Stanton numbers along the model surface and velocity profiles in the region of shock wave-boundary layer interaction are measured and compared with the calculated data. The influence of the laminar-turbulent transition on flow parameters is studied numerically.
Results of numerical simulation of the shock wave passing along a dusty layer are presented; the ... more Results of numerical simulation of the shock wave passing along a dusty layer are presented; the simulation was performed under the one-temperature, one-velocity assumption. It is shown that a system of compression and expansion waves is formed inside the layer, and these waves are successively reflected from the external boundary and solid wall. Regular and irregular reflections of the leading shock wave from the solid wall with different scenarios of instability evolution on the layer edge are described. Possible mechanisms of particle lifting from the surface are described.
Computation results of plane turbulent flows in the vicinity of backward-facing steps with leewar... more Computation results of plane turbulent flows in the vicinity of backward-facing steps with leeward-face angles β = 8, 25, and 45 • for Mach numbers M ∞ = 3 and 4 are presented. The averaged Navier-Stokes equations supplemented by the Wilcox model of turbulence are used as a mathematical model. The boundary-layer equations were also used for the case of an attached flow (β = 8 • ). The computed and experimental distributions of surface pressure and skin friction, the velocity and pressure fields, and the heat-transfer coefficients are compared.
Results of an experimental and numerical study of supersonic turbulent high-enthalpy flow in a ch... more Results of an experimental and numerical study of supersonic turbulent high-enthalpy flow in a channel with cavity are reported. On the basis of wind-tunnel tests performed in the IT-302M short duration wind tunnel, data on the flow structure and on the distribution of static pressure along the model walls were obtained. These data were subsequently used to verify the numerical algorithm. In the calculations, a parametric study of the effects of Mach number, cavity configuration, and temperature factor on flow quantities was performed. It was numerically shown that variation of the above parameters leads to a transition of the flow regimes in the vicinity of the cavity.
The results of numerical modelling and experimental investigations of high-enthalpy turbulent flo... more The results of numerical modelling and experimental investigations of high-enthalpy turbulent flows in the neighborhood of 90-degree backward-facing steps at the Mach numbers M ∞ = 2−4 are presented. The experiments were conducted in the hot-shot wind tunnel IT-302M of ITAM SB RAS. The computations were carried out on the basis of the full Favres-averaged Navier ⎯ Stokes equations augmented by the Wilcox turbulence model. The temperature factor influence on the flow structure in the separated zone and temperature distributions was investigated numerically for different Mach numbers. The wall temperature is shown to affect significantly the quantity and sizes of recirculation vortices as well as the temperature distribution in the zone of flow separation and reattachment. The computational results are compared with experimental data on the pressure distribution on the model surface and the wave structure of the flow.
The results are presented for numerical modelling of two-dimensional flows with large pressure gr... more The results are presented for numerical modelling of two-dimensional flows with large pressure gradients in a wide range of freestream parameters (М = 2−4, Re 1 = 5−30⋅10 6 1/m) and the intensities of perturbing factors. Computations were performed with the use of averaged unsteady Navier ⎯ Stokes equations of a viscous heat-conducting gas. The structure of a turbulent boundary layer at its passage through a single shock and a system of shocks of different strengths, which lie at a fixed distance from one another, was investigated numerically. In the case of the boundary layer passage through a system of shocks, the influence of the first interaction on the structure and separation properties of the boundary layer behind the second shock was investigated. The presence of a preliminary shock was shown to improve the boundary layer capability to withstand separation ahead of the secondary interaction region.
Supersonic (M ∞ = 2–5) turbulent flows in the vicinity of a two-dimensional backward-facing step ... more Supersonic (M ∞ = 2–5) turbulent flows in the vicinity of a two-dimensional backward-facing step with an inclined leeward side are considered by methods of mathematical modeling. The wave structure of the flow with a varied angle of inclination of the leeward side of the step and a varied free-stream Mach number is considered. Introduction. The problem of a supersonic flow past various steps is a classical problem of aerodynamics. Steps with different angles of inclination of the leeward side are frequent elements of the surface of flying vehicles and their propulsion units. Such a configuration is used to organize and stabilize combustion in air-breathing engines. In addition, the problem of the flow past a step is intimately related to the problem of the flow in the base region and in the near wake behind a flying vehicle entering the atmosphere. A detailed review of research performed in this field in 1950s–1970s can be found in [1, 2]. The first analytical study of the flow past a 90 • backward-facing step (BFS) was performed in [3] under the assumption that there exists a streamline dividing the separation region and the external part of the flow. An alternative method of integral moments, which was proposed in [4] and which was first used to describe the flow in the vicinity of a step in [5], is based on the hypothesis that there exists a " free jet " emanating from the rib of the body and a stagnant base region providing compression necessary for flow deflection. In earlier experimental works [6, 7], the main attention was paid to measuring the static pressure in the base region, because it exerts a significant effect on the drag of the body. The wave structure of the flow was studied in later papers [8–10]. Much attention is currently paid to large-scale vortex structures developing in the mixing layer above the separation region and playing an important role in mass, momentum, and energy transfer between the recirculation zone and the external inviscid flow [11]. The base flow is studied by methods of mathematical modeling incorporating simplified models [12] and full Navier–Stokes equations [13–16]. In the present work, we consider the flow in the vicinity of a two-dimensional BFS with an inclined leeward side. The study is performed for moderate angles of inclination of the faces, which is of interest for analyzing the boattailing effect. It is known that a change in the shape of the base part of the body [preliminary expansion with a small (up to 15 •) angle] leads to an increase in pressure in the base region and, hence, to a decrease in drag of the body [17, 18]. Some configurations computed in the present work were examined experimentally in [19]; in turn, the experimental results of [19] were used for verification of computations. In [20, 21], the same flows were studied numerically with the use of the full averaged Navier–Stokes equations supplemented by various semi-empirical models of turbulence. We also computed similar configurations previously [22]. Because of restrictions caused by a small size of the computational domain and an insufficiently refined grid, however, the detailed structure of the flow was not obtained in those computations.
Homogeneous gas-phase pyrolysis of methane in a shock tube is numerically studied. The process of... more Homogeneous gas-phase pyrolysis of methane in a shock tube is numerically studied. The process of pyrolysis occurs under the action of a shock wave reflected from the end face of the tube. An inviscid one-dimensional flow and a viscous two-dimensional flow are considered. Two-dimensional computations are performed on the basis of unsteady Navier–Stokes equations. The kinetic models used are Kassel's simplified gross scheme with 4 reactions and 5 chemical components of methane transformation and a more detailed kinetic scheme with 21 reactions and 13 chemical components. The computations are performed for the Mach number of the incident shock wave equal to M = 5.5. It is shown that the temperature behind the reflected shock wave rapidly decreases because the pyrolysis reaction is endothermic. For this reason, the chemical transformations in the course of pyrolysis are terminated when the total mass concentration of ethylene and acetylene is within 15%. Additional heating of the gas is needed for deeper conversion of methane to ethylene and acetylene.