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Thermophysics and Aeromechanics

2021 year, number 1

Methodical research of unsteady aerodynamic characteristics of the main-stage separation unit of emergency rescue system at supersonic speeds

N.P. Adamov1, A.M. Kharitonov1, E.A. Chasovnikov1, A.A. Dyadkin2, A.N. Krylov2
1Khristianovich Institute of Theoretical and Applied Mechanics SB RAS, Novosibirsk, Russia
2Korolev Rocket and Space Corporation Energiya, Korolev, Russia
Keywords: model main-stage separation unit of emergency rescue system, supersonic speeds, free oscillations, quasi-steady characteristics, damping constant, aerodynamic damping

Abstract >>
A brief description of measuring means, a free-oscillation setup with a transverse sting of the model, and test conditions is reported. A procedure for processing experimental data is described. Quasi-steady and damping aerodynamic characteristics of the pitching moment of the model in the range of Mach numbers M = 1.75-6 are obtained. A comparison of research results with calculated data, as well as with the previous experimental data obtained using the base sting is given. It was found that at M = 3-6 regular undamped oscillations of the model are excited.

Simple method for evaluating the efficiency of high-speed air intakes

V.I. Zvegintsev
Khristianovich Institute of Theoretical and Applied Mechanics SB RAS, Novosibirsk, Russia
Keywords: ramjet engine, air intake, compression process, efficiency, thrust characteristics

Abstract >>
A new and intuitive method for evaluating the efficiency of the compression process in a supersonic air intake is proposed. The method is based on a comparison of the geometric compression ratio of the flow tube in the air intake under consideration with the maximum possible isentropic compression. It is shown that a higher value of the geometric compression ratio in the air intake allows obtaining higher thrust characteristics, with other conditions being identical.

Effect of ice crystals on run-back ice evolution on a wing model

A.V. Kashevarov1, A.B. Miller1,2, Yu.F. Potapov1, A.L. Stasenko1,2
1The Central Aerohydrodynamic Institute n.a. N.E. Zhukovsky, Zhukovsky, Moscow Region, Russia
2Moscow Institute of Physics and Technology, Dolgoprudny, Moscow Region, Russia
Keywords: icing, run-back ice, liquid film, ice crystals

Abstract >>
The influence of ice crystals in an air flow on evolution of run-back ice on the surface of the wing model is numerically investigated for the conditions of experiment in an icing wind tunnel. The results confirm that a change in the mass of ice deposits upon introducing crystals into the flow observed experimentally is associated with absorption of some mass of ice crystals by the water film formed on the surface of a solid at low flow velocities and with film splashing at higher flow velocities. In the first case, the mass of the run-back ice increases; in the second case, it decreases.

Interaction of long-wave disturbances of the external flow with a shock wave on a wedge

I.S. Tsyryulnikov, T.V. Poplavskaya
Khristianovich Institute of Theoretical and Applied Mechanics SB RAS, Novosibirsk, Russia
Keywords: hypersonic flows, stability, receptivity, acoustic disturbances, shock wave

Abstract >>
Relations for the coefficients of transformation of disturbances to pressure oscillations for the case of long-wave disturbances of the external flow are derived from the general analytical solution of the inviscid problem of disturbance interaction with an oblique shock wave on a wedge. Numerical simulations of interaction of long-wave disturbances with a shock wave on a flat plate aligned at an angle of attack in the interval 5°- 20° for a viscous flow regime are performed. Deviations of the transformation coefficients simulated for the viscous case from the inviscid analytical solution in the long-wave approximation are calculated, and corrections for viscous-inviscid interaction in the analytical solution are obtained.

Experimental study of evolution for circular impinging microand macrojets

Yu.A. Litvinenko, M.A. Litvinenko, I.D. Zverkov
Khristianovich Institute of Theoretical and Applied Mechanics SB RAS, Novosibirsk, Russia
Keywords: impinging micro- and macrojets, diffusive combustion, acoustic coherent structures

Abstract >>
The paper describes how the acoustic impact on an impinging jet induces a maldistribution in the radial velocity field within the nearwall zone of spreading jet. The r.m.s. velocity pulsation level in the nearwall jet is lower than in the natural jet. A higher length of the laminar flow zone in a microjet was noted. The development of sinusoid-type instability facilitates a higher combustion efficiency for a propane-butane fuel mixture in the impinging microjet; this reduces the soot emission. The tests demonstrated that the zero acoustic impact makes the flame spectrum more yellow (including the flame from the nearwall zone). This testifies about deficiency of oxidizer (air) and soot presence in the combustion products. The combustion efficiency for diffusive flame in the impinging jet depends on the nozzle diameter and nozzle-target distance.

POD-analysis of the near field of a turbulent circular jet when mixing gases of different densities

V.A. Ivashchenko1,2, E.V. Palkin1,2, V.O. Ryzhenkov1,2, R.I. Mullyadzhanov1,2
1Kutateladze Institute of Thermophysics SB RAS, Novosibirsk, Russia
2Novosibirsk State University
Keywords: turbulence, jets, direct numerical simulation (DNS), POD

Abstract >>
A turbulent circular jet with variable density caused by the mixing of air with gases of different densities (air, helium, and carbon dioxide) is studied. The Reynolds number is fixed for all cases: Re = 5300. Using proper orthogonal decomposition and direct numerical simulation data, a comparative analysis of the three gases under consideration is carried out. It is shown that with a decrease in the ambient gas density, the frequency of coherent structures formation drops, and the number of proper orthogonal decomposition (POD) modes necessary for constructing a low-dimensional flow model decreases.

Angular momentum transfer across the interface of two immiscible liquids

B.R. Sharifullin, I.V. Naumov
Kutateladze Institute of Thermophysics SB RAS, Novosibirsk, Russia
Keywords: hydrodynamics, closed vortex flow, heat and mass transfer, vortex bioreactors

Abstract >>
The paper studies the transfer of angular momentum across the interface of two immiscible liquids in a closed vortex flow, generated in a stationary cylindrical container by a rotating disk, being the upper endwall of the cylinder. When the disk rotates, a centrifugal force begins to act on the upper less dense liquid, which leads to the appearance of a centrifugal circulation of the upper liquid. Since the swirling flow of the upper fluid along the sidewall moves from the rotating disk to the interface, it transfers the angular momentum to the interface, thereby swirling the lower fluid as a result of the action of viscous friction. A forced circulation of the lower fluid arises. Flow visualization and measurement of the circumferential velocity component serve to determine the regularities of the formation of a vortex flow of a denser liquid located under the interface and having no direct contact with the solid disk generating the vortex motion. The development of the centrifugal circulation of the lower liquid is found to be similar to that in a monofluid. The obtained results are of interest for further development of vortex devices and reactors that provide complex vortex motion of ingredients for mass transfer enhancement, optimization of the operation of existing units and for the design of new devices.

Effect of gas temperature and nozzle traverse speed on the deposition efficiency in cold spraying

V.S. Shikalov, S.V. Klinkov, V.F. Kosarev
Khristianovich Institute of Theoretical and Applied Mechanics SB RAS, Novosibirsk, Russia
Keywords: cold spraying, surface activation, critical nozzle traverse speed

Abstract >>
The influence of the stagnation temperature of the accelerating gas flow and that of nozzle travel speed on the deposition efficiency are studied when depositing single Cu-coating tracks by the cold spray technique. The experiments performed clearly show that the nozzle traverse speed substantially affects the value of measured deposition efficiency: the higher is the nozzle traverse speed, the lesser the measured deposition efficiency turns out to be at all other things being identical. Such a behavior can be explained by the fact that the first impacts of particles onto the substrate do not lead to their adhering to the surface and, hence, to coating deposition. It is known that, before the coating starts to grow, it is necessary for the substrate surface to be subjected to a sufficient number of particle impacts. This preparatory stage is called the activation stage, or the delay (induction) stage of the deposition process. It is shown for the first time that the specific (per unit area) mass of the powder consumed at the activation stage depends on the stagnation temperature of the accelerating gas flow: the higher is the stagnation temperature, the lower is the specific mass consumed.

Modeling of heat transfer due to induction heating of laminated glass-metal materials

O.N. Lyubimova, M.A. Barbotko
Far Eastern Federal University, Vladivostok, Russia
Keywords: induction heating, glass-metal composite, glass phase transition, complex heat transfer in layered materials

Abstract >>
The heat-induced variations in material properties for a layered glass-metal composite material were studied for the case of induction heating and the subsequent composite annealing of the sample. A cylindrical sample of the composite (outer metal cylinder covering the glass cylinder) was used in our experimental study. This sample is an imitation of a brittle rock under a high stress. The simulation complexity originates from superposition of the glass point transition within the glass layer, induction heating for the whole sample, and heat radiation from the external metallic surface. Structural and mechanical relaxation processes in glass are calculated using the Boltzmann-Volterra superposition and the Tula-Naraiswami-Mazurin-Moynihan (TNMM) model based on introducing a structural temperature as an additional parameter. The paper offers a mathematical model and a simulation method for calculating the temperature field and material properties distributions during the composite production process. The simulation results are presented for various regimes of heating and for glass-metal composite properties. This approach is useful for evaluating the operation modes of the glass layer annealing and for estimating the evolution of laminated composite materials.

Numerical studies of nonstationary conjugate convective heat transfer in vertical layers of liquid and gas separated by a thin metal partition

V.S. Berdnikov1,2, S.A. Kislitsyn1,2
1Kutateladze Institute of Thermophysics SB RAS, Novosibirsk, Russia
2Novosibirsk State Technical University
Keywords: conjugate heat transfer, thermogravitational convection, vertical layers of liquid and gas, partition, temperature and velocity fields, numerical simulation, finite element method

Abstract >>
The development of a convective flow after sudden heating of a vertical wall that laterally bounds a layer of ethyl alcohol in a system consisting of vertical layers of alcohol and air, separated by a thin metal partition, is studied numerically in a conjugate problem statement. The equations of thermogravitational convection in the Boussinesq approximation, written in variables of temperature, vortex, and stream function, are solved by the finite element method. The development of unsteady hydrodynamic and thermal boundary layers on all four vertical walls is studied. The temperature fields in liquid, gas and in a vertical partition are calculated. The features of the development of the spatial form of the flow and unsteady conjugate convective heat transfer between the layers of liquid and gas affect significantly the unsteady temperature fields and temperature gradients in a thin metal partition. The maximum temperature gradients in the partition appear at the initial stage of flow development.

The influence of molecular properties of gases on heat and mass transfer during combustion of mixed and unmixed reagents

B.F. Boyarshinov
Kutateladze Institute of Thermophysics SB RAS, Novosibirsk, Russia
Keywords: atomic concentration, total enthalpy, transfer via thermal conductivity, diffusion enthalpy transfer, Lewis number, similarity of transfer processes, heat and mass transfer

Abstract >>
Based on the known calculated and experimental data on distribution of temperature and gas compositions near the flame front in jets, it is shown that the nature of a change in the total enthalpy during combustion of mixed and unmixed reagents depends on the molecular properties of gases to different extents, but in the same way. Systems with Lewis numbers less than one have a maximum in the enthalpy profile; if the Lewis number is greater than one, a minimum appears near the flame front. Data on heat fluxes associated with thermal conductivity and diffusion are obtained. It has been found that during combustion of unmixed reagents, the heat flux carried by diffusion is an order of magnitude less than the flux carried by thermal conductivity. For mixed reagents, the heat fluxes carried by diffusion and thermal conductivity exceed the heat fluxes in the flame of unmixed reagents.

Investigation of transient regimes with steam absorption by water solution of lithium bromide

N.S. Bufetov, R.A. Dekhtyar, V.V. Ovchinnikov
Kutateladze Institute of Thermophysics SB RAS, Novosibirsk, Russia
Keywords: absorption, lithium bromide solution, surfactant, Marangoni effect, thermocapillary convection, temperature inhomogeneity

Abstract >>
Transient processes are experimentally investigated at the initial stage of heat and mass transfer with steam absorption on the surface of 57.8% water solution of lithium bromide in a bath with a diameter of 70 mm. The experiments were carried out both with a pure solution and with a solution where n -octanol surfactant was added. It is shown that with a sharp steam pressure increase in the volume above the surface of an absorbing solution, local temperature inhomogeneities are generated on the solution surface. The growth rate of these inhomogeneities is proportional to the growth rate of the steam pressure. It was found that, in contrast to the solution without surfactant, where convective flow is observed only during a short time interval after steam supply to the absorber, in a fixed layer of water LiBr solution with surfactant addition, there is stable thermocapillary convection in the near-surface layer of solution during absorption. It is shown that for variable bottom topography, there can be space-localized zones, where the temperature on the solution surface is determined by the shape of bottom topography.

Synthesis of yttrium oxide Y2O3 nanopowder through evaporation using a high-energy electron beam

D.Yu. Trufanov1, K.V. Zobov1, S.P. Bardakhanov1, A.P. Zavyalov2, I.K. Chakin3
1Khristianovich Institute of Theoretical and Applied Mechanics SB RAS, Novosibirsk, Russia
2Far Eastern Federal University, Vladivostok, Russia
3Budker Institute of Nuclear Physics SB RAS, Novosibirsk, Russia
Keywords: yttrium oxide YO, nanopowder, electron beam accelerator

Abstract >>
The paper presents the experiments on irradiation of the yttrium oxide powder target with a relativistic electron beam and evaporative production of yttrium oxide nanopowder. The phase and chemical consistence, specific surface and particles geometry of nanopowder was studied. A model of mass productivity of nanopowder vs. input e-beam power was tested qualitatively. The effect of continuous operation of setup on the filter catching capacity was studied. A phenomenon of a tubular-shaped structure growing from the hot targeting point toward the electron beam direction was described.

Solubility of potassium, rubidium, and cesium in liquid lithium at high temperatures

R.A. Khairulin, R.N. Abdullaev, S.V. Stankus
Kutateladze Institute of Thermophysics SB RAS, Novosibirsk, Russia
Keywords: lithium-potassium system, lithium-rubidium system, lithium-cesium system, phase equilibrium, melt, gamma-method

Abstract >>
The solubility of heavy alkali metals in liquid lithium was investigated at temperatures from the melting point of Li to ~1200 K by the method of gamma-raying of liquid samples by a narrow beam of gamma radiation. Even at high temperatures, the solubility of K, Rb, and Cs in liquid lithium has been found to be very insignificant. The potassium content in the lithium-rich phase is 0.2 at. % at 850 K and 3.4 at. % at 1212 K. The solubility of rubidium in liquid lithium, within the measurement error, is zero at temperatures from 453 K (melting point of Li) to 800 K and reaches only 0.5 at. % at 1172 K. Cesium is practically insoluble in liquid lithium up to a temperature of 1150 K.