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Journal of Applied Mechanics and Technical Physics

2018 year, number 5

Synthesis of Diamonds from the Microwave Plasma with the use of Supersonic Gas Flows

A. K. Rebrov1, M. V. Isupov1, A. Yu. Litvintsev1, V. F. Burov2
1Kutateladze Institute of Thermophysics, Siberian Branch, Russian Academy of Sciences, Novosibirsk, 630090, Russia
2Joint-Stock Company "ZiO-KOTES", Novosibirsk, 630049, Russia
Keywords: синтез алмазов, микроволновая плазма, резонансная камера, сопло, смесь водорода и метана, высокоскоростной поток, вакуум, diamond synthesis, microwave plasma, resonance chamber, nozzle, hydrogen--methane mixture, high-velocity flow, vacuum

Abstract >>
A new method of deposition of diamond films with the use of supersonic gas flows activated by a superhigh-frequency discharge is implemented for the first time. The operation principle of the proposed gas-discharge system is similar to that of a microwave electrothermal rocket engine. A mixture of hydrocarbons and hydrogen is used as a plasma-forming gas. It is demonstrated that the proposed method allows the plasma-forming gas to be used at pressures far above the upper limit of the working pressures of modern gas-discharge devices of film deposition in the plasma generated by a superhigh-frequency discharge (approximately 40000 Pa).

Investigation of Turbulence on the Molecular Level

S. A. Novopashin
Kutateladze Institute of Thermophysics, Siberian Branch, Russian Academy of Sciences, Novosibirsk, 630090, Russia
Keywords: турбулентность, ламинарно-турбулентный переход, течение Хагена - Пуазейля, второй вириальный коэффициент, turbulence, laminar-turbulent transition, Hagen-Poiseuille, second virial coefficient

Abstract >>
The influence of the molecular structure of gas flows on the characteristics of turbulent flows and the effect of the properties molecules on turbulent processes have been studied. This paper presents a review of the results of study of turbulent processes. Data on flows at the boundary of a supersonic jet and in a tube with an expanding input section, and Hagen-Poiseuille flow are given. Experimental study of Hagen-Poiseuille has shown that the molecular properties of the medium affect the critical Reynolds number. It is shown that in comparing the critical Reynolds numbers for flows of different gases at different pressures, the determining parameter is the second virial coefficient.

Silicon Film Deposition using a Gas-Jet Plasma-Chemical Method: Experiment and Gas-Dynamic Simulation

R. G. Sharafutdinov, P. A. Skovorodko, V. G. Shchukin, V. O. Konstantinov
Kutateladze Institute of Thermophysics, Novosibirsk, 630090, Russia
Keywords: свободная струя, реактор, моделирование, метод DSMC, тонкие пленки кремния, электронно-пучковая плазма, плазмохимическое осаждение, free jet, reactor, simulation, DSMC method, thin silicon films, electron-beam plasma, plasma-chemical deposition

Abstract >>
This paper presents results of an experimental study, numerical calculation, and analysis within the framework of a gas-dynamic model of silicon film deposition by a gas-jet plasma-chemical method. A numerical model of a flow of gas mixtures, flowing out of an annular nozzle unit and flowing into a reactor, is developed, and it allows one to determine a film thickness distribution over the surface of substrates placed in the reactor and describes the experimental data obtained satisfactorily

Hydrogen Dissociation in Flow of Rarefied Gas Through Wire Obstacle

M. Yu. Plotnikov
Kutateladze Institute of Thermophysics, Siberian Branch, Russian Academy of Sciences, Novosibirsk, 630090, Russia
Keywords: обтекание цилиндра, проницаемая преграда, прямое статистическое моделирование, горячепроволочная активация, диссоциация водорода, газофазное осаждение алмаза, cylinder flow, permeable barrier, direct Monte Carlo simulation, hot-wire activation, hydrogen dissociation, gas-phase deposition of diamond

Abstract >>
Direct Simulation Monte Carlo method was used to study plane-parallel flow of hydrogen through an obstacle formed by a series of parallel infinite wires. Particular attention was paid to the influence of the geometric parameters of the wire obstacle, the degree of rarefaction and the velocity of the flow on the degree of hydrogen dissociation due to heterogeneous reactions on the wire surface.

Formation and Evaporation of Near-Wall Fluid Films under Expansion from a Nozzle to the Vacuum

V. N. Yarygin, V. G. Prikhod’ko, I. V. Yarygin
Kutateladze Institute of Thermophysics, Siberian Branch, Russian Academy of Sciences, Novosibirsk, 630090, Russia
Keywords: пристенная пленка жидкости, спутный газовый поток, межфазное взаимодействие, срыв капель, истечение в вакуум, испарение пленки, near-wall liquid film, co-current gas flow, phase interaction, droplet detachment, expansion into vacuum, film evaporation

Abstract >>
Expansion of near-wall films of liquids with different physical properties accompanied by high-velocity co-current gas flow from a nozzle into vacuum is studied experimentally. Local parameters of liquid films inside the nozzle are measured. Gas-droplet flow structure behind the nozzle exit cross-section is examined. Limiting temperatures of liquid films formed on the nozzle outer surface are measured.

Investigation of the Flow Structure on a Small-Scale Gas-Dynamic Setup: Identification of the Secondary Flow in the Case of Exhaustion of a Clustered Supersonic Jet into a Rarefied Space

K. A. Dubrovin, A. E. Zarvin, V. V. Kalyada, V. E. Khudozhitkov, A. S. Yaskin
Novosibirsk State University, Novosibirsk, 630090, Russia
Keywords: разреженный газ, сверхзвуковая струя, моделирование на лабораторных стендах, кластер, фотометрия, спектроскопия, rarefied gas, supersonic jet, modeling on laboratory setups, cluster, photometry, spectroscopy

Abstract >>
A possibility of using small-scale vacuum setups for experimental investigations of supersonic jets escaping from supersonic nozzles into vacuum or a rarefied space is considered. Results of studying the structure of the secondary supersonic flow formed in supersonic jets with developed condensation, which is detected for the first time, are reported. The present investigations are carried out with the use of photometry and spectrometry of jets with the use of emission excited by an electron beam; flow visualization is also performed. The results obtained in the study are analyzed; capabilities and specific features of various methods of flow registration are considered. An empirical model, which establishes the dependence between the detected secondary flow and the process of formation of large clusters in the flow, is developed and justified.

Purifiers in Dust Plasma. Comparison of Numerical Methods

G. I. Sukhinin, M. V. Sal’nikov, A. V. Fedoseev
Kutateladze Institute of Thermophysics, Siberian Branch, Russian Academy of Sciences, Novosibirsk, 630090, Russia
Keywords: пылевая плазма, пылевая частица во внешнем электрическом поле, образование вейков, dust plasma, dust particle in the external electric field, purifier formation

Abstract >>
A self-consistent model for plasma polarization around an isolated dust particle with a size of 10-6 m under the action of an external electric field is presented. It is shown that, for various intensities of the external electric fields behind the dust particle, there are self-consistent potential oscillations. The calculation results are compared with data obtained by using the known numerical approaches.

Dynamics of Protein Folding in the Space of Experimentally Measured Variables: Turbulence Phenomena

S. F. Chekmarev1,2
1Kutateladze Institute of Thermophysics, Siberian Branch, Russian Academy of Sciences, Novosibirsk, 630090, Russia
2Novosibirsk National Research State University, Novosibirsk, 630090, Russia
Keywords: динамика укладки белков, молекулярная динамика, ферстеровский резонансный перенос энергии, потоки вероятностей переходов, турбулентность, структурные функции, protein folding, molecular dynamics, Forster resonance energy transfer, probability transition flows, turbulence, structure functions

Abstract >>
The process of folding of villin subdomain HP-35 has been studied using the method of molecular dynamics. To characterize protein conformations, two variables are introduced which correspond to the distances between fluorophores in experiments on protein folding with the Forster resonance energy. The simulation results show that the flow field of the probabilities of transitions between protein states is filled with eddies. It has been found that in contrast to the previously studied cases of hydrodynamic turbulence and turbulence in protein folding in the three-dimensional conformational space, the structure functions of the flows of various orders depend linearly on the increment in the conformational space. An explanation of this linear dependence based on the -model is proposed, and it is shown that this dependence is not due to the choice of variables for describing the folding process.

Analytical Model for Determining the Effective Size of an Evaporation Region in Pulsed Laser Ablation

A. A. Morozov
Kutateladze Institute of Thermophysics, Siberian Branch, Russian Academy of Sciences, Novosibirsk, 630090, Russia
Keywords: тепловая модель импульсной лазерной абляции, неоднородность температуры поверхности, thermal model of pulsed laser ablation, surface temperature inhomogeneity

Abstract >>
This paper describes the study of the effect of spatial inhomogeneity of surface temperature on the size of a crater forming in the case of pulsed laser ablation. It is assumed that the surface temperature is linearly dependent on laser radiation energy. Analytical expressions determining the effective radius of an evaporation region, characteristic temperatures of the surface on which evaporation occurs, and evaporation depths in the case of the Gaussian distribution of laser radiation energy are derived. It is shown that the analytical dependences obtained are in good agreement with known numerical calculation results.

Effect of the Flow Rate of the Precursor Gas on the Growth Rate of a Fluoropolymer Coating during Hot Wire Chemical Vapor Deposition

A. I. Safonov1, V. S. Sulyaeva2, A. L. Bogoslovtseva1, N. I. Timoshenko1
1Kutateladze Institute of Thermophysics, Siberian Branch, Russian Academy of Sciences, Novosibirsk, 630090, Russia
2Nikolaev Institute of Inorganic Chemistry, Siberian Branch, Russian Academy of Sciences, Novosibirsk, 630090, Russia
Keywords: фторполимер, тонкие пленки, метод HWCVD, газодинамический режим течения, катализатор, fluoropolymer, thin films, HWCVD method, gas dynamic flow regime, catalyst

Abstract >>
The formation of a fluoropolymer coating by chemical deposition has been studied. It has been found that increasing the flow rate of the precursor gas leads to a decrease in the growth rate of the coating. The conditions deposition was analyzed, and the gas dynamic parameters of the process were estimated. It is shown that the estimates are consistent with experimental data.

Thermal-Concentration Convection in a System of Viscous Liquid and Binary Mixture in a Plane Channel with Small Marangoni Numbers

M. V. Efimova1,2, N. Darabi2
1Institute of Computational Modeling, Siberian Branch, Russian Academy of Sciences, Krasnoyarsk, 660036, Russia
2Siberian Federal University, Krasnoyarsk, 660036, Russia
Keywords: начально-краевая задача, преобразование Лапласа, бинарная смесь, термоконцентрационный эффект, initial-boundary-value problem, Laplace transform, binary mixture, thermal concentration effect

Abstract >>
A conjugated initial-boundary-value problem occurring in the movement of a binary mixture and viscous heat-conductive liquid with a common interface surface under the action of thermal-concentration forces is under consideration. A solution describing a stationary flow in layers, temperature distribution, and concentration distribution is determined. The Laplace transform method is used to obtain a nonstationary solution for the problem in images, which makes it possible to describe the evolution of the movement using the numerical inversion of images.

Generalization of a Prantdl Slope Flow Model with a Heavy Impurity

L. Kh. Ingel1,2
1Research and Production Association "Typhoon", Obninsk, 249038, Russia
2A.M. Obukhov Institute of Atmospheric Physics, Russian Academy of Sciences, Moscow, 119017, Russia
Keywords: склоновые течения, модель Прандтля, тяжелая примесь, метели, slope flows, Prandtl model, heavy impurity, snowstorms

Abstract >>
A Prandtl slope flow model is generalized for the case with a homogeneous stationary source of a heavy impurity that significantly changes the medium density. A stationary analytical solution for a velocity of arising flows, temperature deviations, and impurity distribution is obtained. The model describes, for example, some special features of the dynamics of a ground snowstorm above a slope surface.

Energy Storage Device for Electromagnetic Launchers of Solids

A. G. Afonin1, V. G. Butov1, S. V. Sinyaev1, V. A. Solonenko1, G. A. Shvetsov2, S. V. Stankevich2, G. V. Nosov3, M. G. Nosova4
1Research Institute of Applied Mathematics and Mechanics, Tomsk, 634050, Russia
2Lavrent'ev Institute of Hydrodynamics, Siberian Branch, Russian Academy of Sciences, Novosibirsk, 630090, Russia
3Power Engineering Polytechnic Institute, Tomsk, 634050, Russia
4Tomsk State University of Control Systems and Radio Electronics, Tomsk, 634050, Russia
Keywords: электромагнитный ускоритель твердых тел, импульсный магнитогидродинамический генератор, накопитель энергии, electromagnetic launcher of solids, pulsed magnetohydrodynamic generator, energy storage device

Abstract >>
Numerical study has been performed to investigate the characteristics and operating modes of an energy storage device based on a pulsed magnetohydrodynamic generator and a step-up transformer with a stored energy of 25 and 50 MJ and a secondary winding current of 250 kA at the final stage of operation. The operating parameters of such storage devices with rail launchers in the mode of rapid-fire launching of several projectiles.

Measuring the Temperature and Concentration Secondary Electrons in an Argon Electron-Beam Plasma

V. O. Konstantinov, V. G. Shchukin, R. G. Sharafutdinov
Kutateladze Institute of Thermophysics, Siberian Branch, Russian Academy of Sciences, Novosibirsk, 630090, Russia
Keywords: зондовая диагностика, электронно-пучковая плазма, электронная пушка с полым катодом, probe diagnostics, electron-beam plasma, hollow cathode electron gun

Abstract >>
The results of temperature and concentration measurements of secondary electrons in a free jet of argon, activated in an electron beam plasma, carried out using a Langmuir double electrostatic probe. A cold plasmotron prototype with a primary beam energy of 1 keV is used obtain a jet of dense cold plasma with a transverse size of approximately 80 mm and parameters with which silicon layers may be deposited with necessary characteristics in a forvacuum pressure range.

Physical Basis of Methods for Measuring Viscoelastic Properties

V. M. Kulik1, A. V. Boiko2,3
1Kutateladze Institute of Thermophysics, Siberian Branch, Russian Academy of Sciences, Novosibirsk, 630090, Russia
2Khristianovich Institute of Theoretical and Applied Mechanics, Siberian Branch, Russian Academy of Sciences, Novosibirsk, 630090, Russia
3Tyumen' State University, Tyumen', 625003, Russia
Keywords: модули упругости и сдвига, коэффициент потерь, коэффициент Пуассона, формфактор, скорость распространения колебаний, измерения на живых тканях, elasticity and shear moduli, loss coefficient, Poisson's ratio, shape factor, velocity of propagation of oscillations, measurements on living tissues

Abstract >>
The main methods used to measure viscoelastic properties of materials in a wide range of frequencies from 10-4 to 106 Hz are reviewed. It is demonstrated that the accuracy of many experimental methods can be increased by taking into account the shape factors, which depend on the specimen type. An example of the shape factor for a cylindrical specimen is provided, which was determined numerically on the basis of a two-dimensional deformation model taking into account the specimen geometry and Poisson's ratio. The importance of the precise determination of Poisson's ratio for rubber-like and complex-structured materials is demonstrated. Requirements to such measurements and a setup satisfying these requirements are described. Two methods for measuring viscoelastic properties of living tissues (compliance and disturbance propagation velocity) are considered. Based on the developed method of measuring these parameters for materials with a fixed thickness, methods for standartization of measurements of viscoelastic characteristics of living tissues are proposed.

Modeling Flow in a Shock Viscous Layer

A. L. Ankudinov
Zhukovsky Central Aerohydrodynamic Institute, Zhukovsky, 140180, Russia
Keywords: одноатомный газ, поступательная неравновесность, тонкий вязкий ударный слой, 13-моментные уравнения Греда, monatomic gas, progressive nonequilibrium, thin viscous shock layer, 13-moment Grad equations

Abstract >>
This paper considers the two-dimensional problem of high-velocity translational-nonequilibrium flow of a monatomic gas past a surface which was formulated in the theory of viscous hypersonic flows based on macrokinetic 13-moment Grad equations using the approximation of a two-layer thin viscous shock layer (TVSL) near non-thin bodies. A class of similarity variables is proposed that allows the kinetic problem of a TVSL to be reduced to the well-studied Navier-Stokes problem of a TVSL.


I. S. Voitkov1, R. S. Volkov1, A. O. Zhdanova1, G. V. Kuznetsov1, V. E. Nakoryakov2
1National Research Tomsk Polytechnic University University, Tomsk, 634050, Russia
2Kutateladze Institute of Thermophysics, Siberian Branch, Russian Academy of Sciences, Novosibirsk, 630090, Russia
Keywords: аэрозоль, лесной горючий материал, фронт горения, прекращение горения, термическое разложение, пламенное горение, aerosol, forest fuel material, combustion front, burningstop, evaporation, thermal decomposition, flaming combustion

Abstract >>
An experimental study has been performed to investigate the integral characteristics of the processes of heat and mass transfer and phase transformations during interaction of a droplet flow with the combustion front of a highly porous condensed material. The macroscopic regularities of the suppression of flaming combustion and thermal decomposition of typical forest fuel material due to the removal of heat as a result of its absorption during vaporization and convective cooling were studied. Three versions of interaction of a droplet aerosol with burning forest fuel material were considered. The time of combustion termination and the time of thermal decomposition of forest fuel materials were determined. The mechanisms of the main physicochemical processes occurring during interaction of droplet flow with the combustion front of typical forest fuel materials were established.

Instability of the Benard-Marangoni Convection in a Porous Layer Affected by a Non-Vertical Magnetic Field

A. Ah. Abdullah1, Z. Z. Rashed2
1Department of Mathematical Sciences, Umm Al-Qura University, Makkah, 21955, Saudi Arabia
2Department of Mathematics, Al Jouf University, Al Jouf, Saudi Arabia
Keywords: течение Бенарда - Марангони, пористая среда, модель Бринкмана, наклонное магнитное поле, Benard-Marangoni, porous layer, Brinkman model, non-vertical magnetic field

Abstract >>
The onset of the Benard-Marangoni convection in a horizontal porous layer permeated by a magnetohydrodynamic fluid with a nonlinear magnetic permeability is examined. The porous layer is assumed to be governed by the Brinkman model; it is bounded by a rigid surface from below and by a non-deformable free surface from above and subjected to a non-vertical magnetic field. The critical effective Marangoni number and the critical Rayleigh number are obtained for different values of the effective Darcy number, Biot number, Chandrasekhar number, nonlinear magnetic parameter, and angle from the vertical axis for the cases of stationary convection and overstability. The related eigenvalue problem is solved by using the first-order Chebyshev polynomial method.

Impact of the Atmospheric Front Parameters on the Free and Forced Oscillations of the Level and Flow in the Sea of Azov

V. A. Ivanov, T. Ya. Shul'ga
Marine Hydrophysical Institute, Russian Academy of Sciences, Sevastopol, 299011, Russia
Keywords: Азовское море, трехмерная гидродинамическая модель, свободные колебания жидкости, сейши, стационарные течения, штормовые сгоны и нагоны, узловые линии, атмосферный фронт, скорость свободной длинной волны, Sea of Azov, sigma-coordinate model, free oscillations of liquid, seiches, stationary currents, storm surges, nodal lines, atmospheric front, free long wave velocity

Abstract >>
Level oscillations and flow in the basin of the Sea of Azov have been studied by hydrodynamic modeling using the POM Princeton Ocean Model). The hypothesis on the role of the resonance mechanism in the occurrence of extremely large amplitudes of storm surge and seiche oscillations depending on the velocity and time of motion of atmospheric fronts of the Sea of Azov has been tested. It is found that at the same wind, baric disturbances moving over the Sea of Azov induce forced oscillations, and after the disturbances cease, free oscillations with amplitudes that are 14% higher than those obtained at constant atmospheric pressure. It is shown that the movement of the atmospheric front (whose speed and time are selected under the assumption that waves with maximum amplitudes are generated) plays an important, but not decisive role in the development of the flow structure and level oscillations in the Sea of Azov.

Chain of Physically Related Independent Mechanical Oscillators

A. D. Sergeev
Institute of Problems of Mechanical Engineering, Russian Academy of Sciences, St. Petersburg, 199178, Russia
Keywords: цепочки твердых тел, гипотеза Эйнштейна, chains of rigid bodies, Einstein's hypothesis

Abstract >>
A lumped-parameter mechanical system consisting of a chain of physically related solids, each of which has one rotational degree of freedom. It is shown that inertial-free elastic elements that connect absolutely rigid bodies of the chain can be chosen in such a way that the mechanical structure acquires the properties of the so-called absolute mechanical filter. The motion of any inertial element of this system is described by the equation of a classical harmonic oscillator with one degree of freedom. Using the system considered as an example, it is shown that there is a relationship between the models of classical and quantum mechanics. From the positions of modern classical mechanics, this lumped-parameter system confirms the Einstein's hypothesis well-known in theoretical physics and stating that a solid is a system of independent oscillators.

Solving the Motion Equations of a Viscous Liquid with a Nonlinear Dependence between a Velocity Vector and Some Spatial Variables

D. V. Knyazev
Institute of Continuous Media Mechanics, Ural Branch, Russian Academy of Sciences, Perm, 614013, Russia
Keywords: уравнения Навье - Стокса, точные решения, разделение переменных, переопределенные системы, Navier- Stokes equations, exact solutions, separation of variables, overdetermined system

Abstract >>
It is shown that the classes of exact solutions of Navier-Stokes equations with a linear and inversely proportional dependence between velocity components and some spatial variables can be expanded by adding finite perturbations, being power or trigonometric series or their sections on one of the coordinates. An example of single integration of three-dimensional equations of motion of a viscous liquid, which are reduced to an equation for the potential of two velocity components, is given.

Temperature effect on the Fracture of Laser Welds of Aviation Aluminum Alloys

E. V. Karpov1, A. G. Malikov2, A. M. Orishich2, B. D. Annin1
1Lavrent’ev Institute of Hydrodynamics, Siberian Branch, Russian Academy of Sciences, Novosibirsk, 630090, Russia
2Khristianovich Institute of Theoretical and Applied Mechanics, Siberian Branch, Russian Academy of Sciences, Novosibirsk, 630090, Russia
Keywords: лазерная сварка, алюминиево-литиевый сплав, прочность, пластичность, влияние температуры, laser welding, aluminum-lithium alloy, strength, plasticity, temperature effect

Abstract >>
This paper describes an experimental study of the effect of temperature on the fracture of laser welds of Mg- and Cu-containing aviation aluminum alloys. The fracture of alloys and their welds under a uniaxial loading at temperatures of -60, 20, and 85 oC is investigated. It is revealed that the strength and ultimate strain of welds of Cu-containing alloys decrease as temperature rises because of the formation of immobile hot spots of localized plastic shifts. Heating and cooling suppress the Portevin- Le Chatelier effect and significantly reduce the ultimate strain of a Mg-containing alloy, even though such reduction is not observed in a weld. It is shown that, at a negative temperature, the maximum limiting lengthening of the weld of a Mg-containing alloy is achieved, while the formation of secondary cracks is activated during heating.

Plasma Reinforcement of Working Surfaces of Parts of a Bottom Hole Pump

S. A. Gasymova
Azerbaijan State Oil and Industry University, Baku, AZ1000, Azerbaijan
Keywords: штанговый глубинный насос, модификация внутренней поверхности цилиндра, плазма, ВЧ-разряд, микротвердость, модуль упругости, bottom hole pump, modification of the inner surface of a cylinder, plasma, HF charge, microhardness, elasticity modulus

Abstract >>
The possibility of using nitrogen-containing plasma that forms in a high-frequency charge is shown, and the plasma effect on changes in the physical and chemical properties of the inner surface of the cylinder is tested. The properties are estimated in accordance with the ISO 14577 standard on a “Nanoskan-3D” device. It is revealed that the microhardness of a bottom hole pump cylinder treated in the plasma of a high-frequency charge increases by a factor of 2 to 2.5, while the elasticity modulus becomes 25 to 40% larger.

Monocrystalline Silicon Plasma Expansion Induced by Millisecond Laser

M. Guo1,2, G. Jin3, X. Gao3
1Institute for Interdisciplinary Quantum Information Technology, Changchun, 130052, China
2Jilin Engineering Laboratory for Quantum Information Technology, Changchun, 130022, China
3School of Science, Changchun University of Science and Technology, Changchun, 130022, China
Keywords: миллисекундный лазер, монокристаллический кремний, плазма, теневая фотография, millisecond laser, monocrystalline silicon, plasma, shadowgraphy

Abstract >>
Ablation of monocrystalline silicon to atmospheric environment induced by a millisecond pulse of an Nd:YAG optical laser with a wavelength of 1064 nm is studied. Shadowgraphy is applied to study the process of monocrystalline silicon plasma expansion for the laser energy density of 955.4-2736.0 J/cm2. It is shown that the outer boundary of the plasma plume diffuses outside with time. Plasma expansion occurs in both axial and radial directions, but the velocity of plasma expansion in the radial direction is smaller than in the axial direction. Two centerlines of the laser action are symmetric. The maximum expansion velocity of 162.1 m/s is reached with the laser energy density of 2376.0 J/cm2, and a laser-supported combustion wave is generated in this case. In contrast to monocrystalline silicon under the action of a short-pulse laser, the millisecond laser action can make the plasma expansion velocity increase for the second time. A material splash can be observed from the expansion images in the case of a high laser energy density.

Effect of the Downstream Crescent-Shaped Block Height on the Flat-Plate Film Flow and Cooling Performance

C. Zhang1, Z. Wang2
1Tianjin Key Laboratory for Advanced Mechatronic System Design and Intelligent Control, Tianjin, 300384, China
2School of Energy and Power Engineering, Shandong University, Jinan, 250061,China
Keywords: газовая турбина, охлаждающая пленка, высота серповидного блока, пара ``антивихрей'', коэффициент вдува, эффективность охлаждения, gas turbine, film cooling, crescent-shaped block height, anti-kidney vortex pair, blowing ratio, cooling effectiveness

Abstract >>
Numerical simulations are performed to systematically investigate the effect of the downstream crescent-shaped block height on the flow field and cooling performance for a configuration with a single row of an infinite number of inclined cylindrical holes at various coolant-to-mainstream blowing ratios. The numerical results show that placing a downstream block can significantly alter the downstream flow field due to generation of an additional anti-kidney vortex pair, which improves the cooling performance. Optimal block heights are determined for various blowing ratios.