Supersonic rarefied gas flow through a wire grid

Plotnikov, M. Yu.; Ребров, А. К.

doi:10.1134/s0021894413040019

Cited by 7 publications

(3 citation statements)

References 5 publications

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“…The use of a wire net with a high‐velocity gas flow has an important disadvantage because of destroying a high‐velocity flow and backscattering of activated particles. This was quantitatively shown in the results of computational modeling using the direct Monte Carlo simulation . Important problems were solved by creation of the reactor using the spiral of refractory material, inserted into a chamber with the inlet nozzle, and the exit to a substrate.…”

Section: Introductionmentioning

confidence: 99%

The gas‐dynamic synthesis of diamond by thermal activation

Emel’yanov

Ребров

Yudin

2014

Physica Status Solidi (a)

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The study presents results on deposition of diamond structures from high‐velocity flows of carbon‐containing a gas mixture activated by hot surfaces. Important problems were solved by creation of the reactor using a spiral of heat‐resistant material, inserted into the chamber with an inlet nozzle. The possibilities of diamond synthesis in wide parameters ranges (pressure from 10−4 to 100 Torr, flow rates from 500 to 3000 sccm, substrate temperature from 1100 to 1600 K) have been studied experimentally. For analysis of the hydrogen flow, the direct simulation Monte Carlo (DSMC) method was used. The activation–deactivation influence of reactor surfaces has been taken into account. The results of diamond crystal synthesis are presented for the cases of joint and separated H2 and CH4 gas delivery. Due to retaining the catalytic tungsten properties in the case of separated gas delivery, an increasing growth rate of diamond crystals was discovered.

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Section: Introductionmentioning

confidence: 99%

The gas‐dynamic synthesis of diamond by thermal activation

Emel’yanov

Ребров

Yudin

2014

Physica Status Solidi (a)

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“…Supersonic flow past permeable screens (grids, perforated plates, lattices and so on) is of interest in many technological applications [1][2][3][4][5], as well as in the problems of analysis of certain natural phenomena such as gas dynamics of splintering of disintegrating meteoroids and other [6][7][8]. The formulation of the adequate boundary conditions on the surfaces of a strong gas dynamic discontinuity that simulate the permeable screens [9,10] is of fundamental value.…”

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confidence: 99%

“…The formulation of the adequate boundary conditions on the surfaces of a strong gas dynamic discontinuity that simulate the permeable screens [9,10] is of fundamental value. In the case of fairly permeable screens located transversely supersonic stream, the flow takes place without formation of global stand-off shock wave [2,5,10]. A very simple model of the permeable screen is the plane cascade (lattice) of parallel circular cylinders located at an identical distance from each other.…”

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Hysteresis in Supersonic Flow Past a Plane Cascade of Cylindrical Rods

Guvernyuk

Maksimov

2021

Fluid Dyn

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Abstract— The results of numerical simulation of the interaction of supersonic flow with a permeable screen in form of an infinite plane cascade (lattice) of circular cylinders are given. The interaction regime in which the shocks ahead of the cylinders are localized on the scale of the cascade step is considered. The multi-block computational technique in which the viscous boundary layers are resolved by means of local grids using the Navier–Stokes equations, while the effects of inteferrence between the shock-wave structures in supersonic wake are described within the framework of Euler’s equations. The action of shock waves induced by the neighboring elements of lattice to the near-wake region behind the intermediate elements can ambiguously affect the aerodynamic lattice performance as well as generate time-dependent phenomena in the wake. The flow regimes are classified depending on continuous increase and decrease in the free-stream supersonic air flow in the Mach number range from 2.4 to 4.2 with reference to the lattice of the 80% permeability. The sources of the hysteresis behavior of the lattice aerodynamic drag with respect to the Mach number and the mechanisms of the onset of self-oscillating wake flow regimes are discussed.

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Modeling the flow of activated H₂+ CH₄mixture by deposition of diamond nanostructures

2017

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Abstract. Algorithm of the direct simulation Monte Carlo method for the flow of hydrogen and methane mixture in a cylindrical channel is developed. Heterogeneous reactions on tungsten channel surfaces are included into the model. Their effects on flows are analyzed. A onedimensional approach based on the solution of equilibrium chemical kinetics equations is used to analyze gas-phase methane decomposition. The obtained results may be useful for optimization of gas-dynamic sources of activated gas diamond synthesis.The method of Hot-Wire Chemical Vapor Deposition (HWCVD) is widely used for diamond deposition from an activated precursor gas. Its main feature is activation of a gas precursor on metallic surfaces: wires, placed in a virtually resting gas [1] or in high-speed flows [2], as well as cylindrical channels [3]. The presented work is devoted to the numerical study of gas-dynamic aspects of the rarefied gas flow in a hot tube with dissociation and recombination on the surface. The algorithm of direct simulation Monte Carlo (DSMC) method [4] with majorant frequency scheme [5] is used for the numerical analysis and optimization of approaches to deposition of diamond-like films using the hot tubes. In [6][7][8] the importance of taking into account dissociation and recombination in the analysis of flows in the tubes was shown. The use of a cylindrical channel as an activator provides better gas dissociation due to multiple collisions with the surface [6][7][8] in comparison with the case of interaction of the supersonic flow with a wire obstacle [9,10]. A one-dimensional approach based on the solution of equilibrium chemical kinetics equations was used to analyze gas-phase methane decomposition.The main goal of the presented work is to analyze the influence of the determining parameters on the composition and energy state of the gases flowing to the substrate. Particular attention is paid to the behavior of atomic hydrogen, one of the main components that determine the synthesis of diamond structures.

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Supersonic rarefied gas flow through a wire grid

Cited by 7 publications

References 5 publications

The gas‐dynamic synthesis of diamond by thermal activation

The gas‐dynamic synthesis of diamond by thermal activation

Hysteresis in Supersonic Flow Past a Plane Cascade of Cylindrical Rods

Modeling the flow of activated H₂+ CH₄mixture by deposition of diamond nanostructures

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Supersonic rarefied gas flow through a wire grid

Cited by 7 publications

References 5 publications

The gas‐dynamic synthesis of diamond by thermal activation

The gas‐dynamic synthesis of diamond by thermal activation

Hysteresis in Supersonic Flow Past a Plane Cascade of Cylindrical Rods

Modeling the flow of activated H2+ CH4mixture by deposition of diamond nanostructures

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Modeling the flow of activated H₂+ CH₄mixture by deposition of diamond nanostructures