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Thermophysics and Aeromechanics

2022 year, number 6

1.
On “new methodologies of processing” of results calculated for rotating detonation engines and of results of force measure-ments for ramjet models tested in super-sonic test benches

A.N. Kraiko
Baranov Central Institute of Aviation Motors, Moscow, Russia
Keywords: rotating detonation engine (RDE), forces measured in “hot” and “cold” runs, model in a supersonic test bench, effective thrust

Abstract >>
It is shown that the “new methodologies” of processing and using results calculated for rotating detonation engines, as well as those of recent measurement of forces acting on the models of ramjet (rotorless) models in “hot” and “cold” runs in supersonic test benches, which are developed and promoted by S.M. Frolov and V.I Zvegintsev with their colleagues, are incorrect.



2.
Determination of the propulsion performance characteristics of air-breathing jet engine

V.I. Zvegintsev
Khristianovich Institute of Theoretical and Applied Mechanics SB RAS, Novosibirsk, Russia
Keywords: air-breathing jet engine, aerodynamic drag, “real thrust”, flight tests, bench tests, trajectory calculation

Abstract >>
The traditional approach to measuring the thrust of air-breathing jet engines (ABJEs) was proposed by B.S. Stechkin in 1929. In this approach, the thrust is determined as the difference between the momenta of the gas flows at the engine inlet and outlet. The approach involves some methodological and terminological problems. Based on a critical analysis of available concepts, the present article proposes a new approach to determining the ABJE thrust in the form of the decrease of the initial drag of the aircraft + ABJE system when the power plant operates with fuel supply and energy release. For the thrust thus obtained, we propose using the term “real thrust”. It is shown that the proposed approach eliminates terminological problems and simplifies the technique for measuring the thrust characteristics of the ABJE. The paper considers various options for applying the proposed approach to the determination of the “real thrust” for different cases of using and modeling ABJEs, including the calculation of flight trajectories of the aircraft with ABJE.



3.
Study of thermal efficiency of a wall gas screen injected through the holes in the transverse trench

M.A. Pakhomov, M.V. Filippov, I.A. Chokhar, V.I. Terekhov
Kutateladze Institute of Thermophysics SB RAS, Novosibirsk, Russia
Keywords: wall gas screen, thermal efficiency, injection through cylindrical holes, transverse trench

Abstract >>
We present the experimental results on the thermal efficiency in a wall gas screen injected through inclined cylindrical holes along a smooth surface, and when a secondary flow is blown through cylindrical holes into a transverse trench. The thermal efficiency fields of the wall screen were measured using an infrared camera. In the case of blowing into a trench, the experimental data are characterized by an insignificant influence of the injection parameter on the thermal efficiency of the wall screen for all the trenches under study. It has been established that an increase in the trench depth leads to an increase in the thermal efficiency of the wall gas screen. The maximum increase in thermal efficiency is achieved for a trench with relative depth h/d = 0.94 . The data of the measurements presented are compared with the experimental and numerical results of other authors for the cases of injecting through the holes into a transverse trench.



4.
Modeling of air blowing control on an axisymmetric body in a low-velocity gas flow

V.I. Kornilov, A.N. Popkov
Khristianovich Institute of Theoretical and Applied Mechanics SB RAS, Novosibirsk, Russia
Keywords: boundary layer control, turbulent boundary layer, distributed blowing, axisymmetric body, perforated surface, friction

Abstract >>
Results of experimental and numerical studies of the properties of a turbulent boundary layer modified with a control action in the form of distributed air blowing through a high-technology perforated wall are presented. The wall is part of the surface of an elongated axisymmetric body in a low-velocity gas flow. The Reynolds number Re** based on the momentum thickness δ** ahead of the perforated region formed by holes 0.14 mm in diameter with microchannels with a small aspect ratio is 2660. The area-averaged blowing coefficient Cb varies in the interval 0 - 0.00885. As the streamwise coordinate increases up to the distance 550δ** from the blowing region, the local friction is seen to decrease consistently; the greatest value of the local friction is 64% directly in the blowing region in the case of the maximum blowing intensity.



5.
Thermal conductivity of the R-32/R-125 (15/85) mixture in the vapor phase

E.P. Raschektaeva, S.V. Stankus
Kutateladze Institute of Thermophysics SB RAS, Novosibirsk, Russia
Keywords: thermal conductivity, mixed refrigerant, vapor phase

Abstract >>
The thermal conductivity of the R-32/R-125 (15/85) mixture was investigated in the temperature range of 305 - 411 K and pressures of 0.1 - 1.8 MPa. Measurements were carried out by the stationary method of coaxial cylinders. The error of the experimental data on thermal conductivity was 1.5 - 2.5%, and the measurement errors of temperature and pressure did not exceed 0.05 K and 4 kPa, respectively. A generalizing equation for calculating the thermal conductivity as a function of pressure and temperature was obtained. The thermal conductivity on the condensation line and in the ideal gas state was determined.



6.
Equation for the viscosity coefficient of liquid, gas and fluid of inert gases. Krypton

O.S. Dutova1, P.P. Bezverhiy2
1Kutateladze Institute of Thermophysics SB RAS, Novosibirsk, Russia
2Nikolaev Istitute of Inorganic Chemistry SB RAS, Novosibirsk, Russia
Keywords: viscosity, density, temperature, pressure, gas, liquid, krypton

Abstract >>
Using the previously established dependence of the excess viscosity on the internal energy density, a simple low-parameter equation was obtained to describe the krypton viscosity coefficient in a wide range of state parameters. It was shown that the proposed low-parameter equation for calculating the viscosity coefficient of liquid and gas allows for reliable extrapolation beyond the limits of the studied area.



7.
Numerical simulation for evolution of local disturbances generated by two synchronous distant sources in a supersonic boundary layer

A.A. Yatskikh, L.V. Afanasiev
1Khristianovich Institute of Theoretical and Applied Mechanics SB RAS, Novosibirsk, Russia
2Khristianovich Institute of Theoretical and Applied Mechanics SB RAS, Novosibirsk,Russia
Keywords: supersonic boundary layer, numerical simulation, local disturbance, laminar-turbulent transfer

Abstract >>
The paper presents results of numerical simulation for development of localized disturbances emerging from a single source or double synchronous sources in a laminar boundary disturbances at the plate with the flow with the Mach number Ì = 2 (variants for different distances between sources). Simulation was performed using the FlowVision software complex at the parameters typical for T-324 wind tunnel (developed by ITAM SB RAS). The problem was studied in the range of linear development of disturbance. The study demonstrates that, depending on the distance between the sources, the generated disturbances might either enhance or decay in the downstream flow. The frequency-wavelet analysis of disturbance structure was performed. Two distanced local synchronous sources generate the disturbances with wavelet spectra: these spectra exhibits nodes and crests; their positions depend on the distances between two sources.



8.
Experimental investigation of the flow structure in a single trench hole

V.I. Terekhov1,2, V.V. Terekhov1, I.A. Chokhar1, N. Yan Lun1,2
1Kutateladze Institute of Thermophysics SB RAS, Novosibirsk, Russia
2Novosibirsk State Technical University, Novosibirsk, Russia
Keywords: aerodynamics, single trench hole, flow separation, pressure fields, velocity fluctuations

Abstract >>
A technique is described and the results of an experimental study of the aerodynamic structure of a turbulent streamlining, velocity fluctuations and pressure fields on the surface of a single trench hole located on the wall of a flat rectangular channel are presented. The trench hole cross-section is a cylindrical segment with hemispheres at its edges. The measurements were carried out with a two-component laser-Doppler velocity meter at two angles of hole inclination relative to the flow direction φ=0 è 45°. The development of the flow in the direction transverse to the trench, as well as along its span, was studied. The fundamental difference between the velocity fields and their fluctuations in a trench located normally and at an angle to the flow is shown.



9.
Water motion near graphene and its electric conductivity

D.V. Sorokin1,2, D.A. Shatilov1,2, V.A. Andruschenko1, M.S. Makarov1, V.S. Naumkin3, D.V. Smovzh1,2
1Kutateladze Institute of Thermophysics SB RAS, Novosibirsk,Russia
2Novosibirsk State University, Novosibirsk,Russia
3Kutateladze Institute of Thermophysics SB RAS, Novosibirsk, Russia
Keywords: graphene, chemical deposition from gaseous phase, carbon, sensor, flow sensor

Abstract >>
The paper is the study of electric resistance of a graphene layer washed by a liquid with different flow rate parameters. Experiments demonstrate that if the fabricated composite (graphene upon a PET/EVA polymeric substrate) is submerged into distilled water, the sample resistance increases by 120 %. Meanwhile, the flow of liquid near the graphene layer decreases this gain in the electric conductivity. The effect offers a general design of a flow rate sensor based on the graphene layer, taken as a sensitive matrix. The study demonstrates that this design of graphene flow sensor (taken for distilled water) exhibits a linear dependency of the sensor resistance on flow rate.



10.
The structure of the proximal anastomosis flowin stationary mode at moderate Reynolds numbers

V.M. Molochnikov1,2, A.N. Mikheev3, A.B. Mazo4, E.I. Kalinin4, M.A. Klyuev1,2, N.D. Pashkova1,2
1FRC Kazan Scientific Center RAS Kazan, Kazan,Russia
2Kazan National Research Technical University named after A.N. Tupolev, Kazan,Russia
3FRC Kazan Scientific Center RAS, Kazan,Russia
4Kazan (Volga Region) Federal University, Kazan,Russia
Keywords: channel branching, flow separation, experiment, direct numerical simulation, secondary flows, flow turbulence

Abstract >>
Results of an experimental study and direct numerical modeling of the steady flow in a channel branching region simulating the proximal anastomosis of the femoral artery, are reported. The Reynolds number was Re = 1500, which value corresponds to the maximum blood flow during the period of heart contractions. The ratio of the rates of the liquid flows through the branch and the main channel was a varied parameter. Regularities in the development of the flow structure in the primary channel and in the branch region are revealed, with much attention having been paid to flow separation regions. The occurrence of secondary flows localized within the separation regions has been established. The ranges of the ratio of the flow rates at which flow turbulence signs appear in the mixing layer at the interface between these regions are determined.



11.
Experimental study of dispersed flows in microchannels for 3D printing of composite materials

A.V. Kovalev1,2, A.A. Yagodnitsyna1,2, A.V. Bilskiy1
1Kutateladze Institute of Thermophysics SB RAS, Novosibirsk,Russia
2Novosibirsk State University, Novosibirsk,Russia
Keywords: microchannels, two-phase flows, plug flow mode, microdroplets, 3D printing

Abstract >>
The paper studies the segmented flow modes of immiscible liquids in microchannels with T- and X-shaped inputs for 3D printing technologies. On the basis of the flow visualization results, mode maps with a distinguished area of stable plug flow are constructed. A fair coincidence of the maps built on the basis on the superficial flow velocities is revealed, and the influence of the channel input on the boundaries of flow modes is shown to be insignificant. When using a less viscous carrier phase, the region of a stable plug mode is demonstrated to expand towards higher superficial flow velocities. The separation of microdrops from the trailing edges of plugs is investigated. It has been found that the transition to the separation of microdrops is described in terms of the capillarity number, constructed from the bulk velocity of the phases, and the ratio of phase flow rates. Thus, a range of dimensionless parameters of microchannel devices, suitable for 3D printing of composite materials with specified properties has been determined.



12.
Simulation study of aerodynamics and heat transfer for an advanced design of pulverized-coal-fired furnace

S.V. Alekseenko1, A.A. Dekterev1,2, V.A. Kuznetsov1,2, E.S. Tepfer1
1Kutateladze Institute of Thermophysics SB RAS, Novosibirsk,Russia
2Siberian Federal University, Krasnoyarsk,Russia
Keywords: furnace chamber, four-vortex combustion scheme, mathematical simulation, coal combustion, aerodynamics, heat transfer

Abstract >>
The paper deals with simulation study of aerodynamics and heat transfer for a case of a four-vortex furnace chamber designed for jet fire of brown coal from Eastern coal deposits. The combustion modeling is achieved by a set of linked submodels: they describe turbulent gas flow? Thermal and radiative heat transfer, the processes of degradation and burning of coal particles, NOx generation. Simulation demonstrated that using of these types of brown coal in a specific-design furnace chamber creates a steady four-vortex flow structure that provides a uniform temperature field in the volume and admissible generation of NOx .



13.
Effects of different processing parameters on laser water jet machining of silicon

Y.L. Chen1, X. Li1, X.H. Chen2, H. Li1
1Hefei University of Technology, Hefei, Anhui ,China
2Anhui Jianzhu University, Hefei, Anhui,China
Keywords: laser water jet processing, silicon, processing parameters, groove, depth

Abstract >>
Laser water jet processing is a new hybrid method developed on the basis of traditional laser processing technology. It combines high laser processing efficiency with the impact and cooling effects of water jets. Laser water jet processing can effectively process hard and brittle materials such as silicon. In-depth study of the processing technology has important practical significance. For this reason, the controlled variable method is used to study the influence of different processing parameters on groove depth. The research results show that with the increase of current and laser pulse width , the groove depth gradually increases; with the increase of laser repetition frequency and water jet velocity, the groove depth increases first and then decreases. The experiment of laser water jet processing silicon can provide guidance for processing other difficult-to-process materials in the future.



14.
Evolution of wetting of a copper surface treated with nanosecond laser radiation

M.M. Vasilev1,2, A.A. Rodionov1,2, Yu.G. Shukhov1, F.A. Samokhvalov1,2, S.V. Starinskiy1,2
1Kutateladze Institute of Thermophysics SB RAS, Novosibirsk,Russia
2Novosibirsk State University, Novosibirsk,Russia
Keywords: nanosecond pulsed laser ablation, surface wettability properties, surface morphology

Abstract >>
Laser radiation is a leading tool in the field of materials processing and design. Recently, the prob-lem of controlled changes in the wetting properties of metals realized by the micro- and nanostructuring of surfaces has been actively investigated. In the pre-sent paper, the influence of the conditions of nano-second laser treatment on the wetting properties of a copper surface in the mode of formation of a ran-domly distributed hierarchical structure is investigat-ed. Special attention is paid to the evolution of the contact angle of wetting over time. The mechanisms of changing the wetting properties over time are con-sidered. It is shown that the overlap of laser spots is more important than the fluence in the beam from the point of view of hydrophobization of the copper surface.



15.
Chemoconvective mixing in a Y-shaped flow microchannel

D.A. Bratsun1, R.R. Siraev1, E.A. Mosheva1,2, A.V. Shmyrov1,2, A.I. Mizev1,2
1Perm National Research Polytechnic University, Perm,Russia
2Institute of Continuous Media Mechanics of the Ural Branch of RAS, Perm,Russia
Keywords: flow-type reactor, instability, mixing efficiency, chemoconvective effect

Abstract >>
The flow-type microreactors, being designed for small-scale production of pharmaceutical substances, have a moderate volume and ensure steady synthesis for pharmaceutical production while using noninva-sive methods for mixing of ingredients. The paper describes experimental and simulation study of the efficiency for natural convection mechanisms for so-lutions mixing in a Y-type symmetric microreactor. The mixing zone is arranged for discovery of con-vection potential. We consider both variants of chemically inert and chemically active systems. A model reaction is represented by a rapid acid-base neutralization reaction. The theoretical model com-prises the 3D Navier-Stokes equation and the reac-tants transfer equation (written with account for non-linear diffusion). Experimental and numerical results have been compared. The dependency for the effec-tive mixing length on the instability type and sol-vents flow rates was found.



16.
High-speed visualization of cavities, arising in a slit channel of complex shape

M.A. Tsoi, S.G. Skripkin, I.V. Naumov, A.Y. Kravtsova
Kutateladze Institute of Thermophysics SB RAS, Novosibirsk, Russia
Keywords: cavitation, NACA 0012 series foil, high-speed visualization, Strouhal number

Abstract >>
The article presents the results of an experimental study of the cavitation flow around the NACA 0012 series foil in a narrow slit channel with a width of 1.2 mm. The aspect ratio of the streamlined body was 0.02. To identify the main features of the two-phase flow, high-speed visualization was performed using the Photron FASTCAM NOVA S12 camera with a sampling frequency of 20 kHz. The internal structure of cavities was detected. The main frequencies of cavities formation in the flow were determined using digital processing of visualization data. The close location of the channel walls was shown to significantly affect the return flow propagation under the cavity and its separation.



17.
Bubble growth in a volatile liquid droplet: interface dynamics

Yu.A. Peschenyuk1,2, A.A. Semenov1,2, G.E. Aivazyan3, M.S. Lebedev4, E.Ya. Gatapova1,2
1Kutateladze Institute of Thermophysics SB RAS, Novosibirsk, Russia
2Novosibirsk State University, Novosibirsk, Russia, Novosibirsk, Russia
3National Armenian Polytechnic University, Erevan, Armenia
4Nikolaev Institute of Inorganic Chemistry SB RAS, Novosibirsk, Russia
Keywords: cavitation, NACA 0012 series foil, high-speed visualization, Strouhal number

Abstract >>
The study is focused on the process of bubble growth inside a intensively evaporating liquid droplet placed on a hot structured surface made of black silicon. Experiments are carried out with volatile fluids FÑ-72, HFE 7100, ethanol and water. The method using the Schliren-system was developed for study of bubble growth inside a droplet. The contact line speed was measured during microdroplet evaporation, including the case of a growing bubble inside the droplet. The speeds of the contact for droplet evaporation with/without bubble were compared. The contact line instability was found, emerging due to a developed structure of substrate; it facilitates the enlargement of local flows in microregions. This facilitates the heat transfer enhancement.



18.
Investigation of dielectric liquid FC-72 boiling in a slot microchannel

F.V. Ronshin, Yu.A. Dementiev, E.A. Chinnov
Kutateladze Institute of Thermophysics SB RAS, Novosibirsk,Russia
Keywords: boiling, slot microchannel, dielectric liquid

Abstract >>
Microchannel cooling systems are widespread due to their efficiency. In this work boiling of dielectric liquid FC-72 in a flat microchannel with a height of 66 μm and a width of 10 mm was studied. Heating was carried out by a thin-film ITO heater in direct contact with the working liquid. The flow regimes at boiling in a wide range of liquid flow rates were investigated. It is shown that boiling regimes in a flat microchannel differ significantly from the flow regimes in circular and rectangular mini- and microchannels. The dependences of heat flux on the temperature head have been plotted. The dependence of the heat transfer coefficient on the heat flux was investigated for different regimes of the two-phase flow.



19.
Plasma ignition of solid fuels at thermal power plants. Part 2. 3D modeling of the furnace of a pulverized coal boiler

V.E. Messerle1,2,3, A.B. Ustimentko4,5, K.A. Umbetkaliev4,5
1Institute of Combustion Problems, Almaty, Kazakhstan
2Kutateladze Institute of Thermophysics SB RAS, Novosibirsk,Russia
3Al-Farabi Kazakh National University, Almaty, Kazakhstan
4Institute of Combustion Problems, Almaty,Kazakhstan
5Al-Farabi Kazakh National University, Almaty,Kazakhstan
Keywords: boiling, slot microchannel, dielectric liquid

Abstract >>
This paper presents calculation results on plasma ignition and combustion of coal in the furnace of the PK-39-II boiler at Reftinskaya SDPP. For mathematical modeling of coal combustion in the boiler furnace, a three-dimensional mathematical model Cinar ICE and a software package for physical modeling and calculation of hydro-dynamics, heat and mass transfer and combustion of fuels in the volume of furnace devices were applied used. Cal-culations were performed for two regimes of pulverized coal combustion: the traditional one and using plasma activa-tion of coal combustion. It is shown that the use of plasma-fuel systems (PFS) allows optimization of the coal com-bustion process in the combustion chamber. Three-dimensional modeling of a pulverized coal furnace equipped with a PFS allows one to determine the optimal PFS layout on boilers of thermal power plants.



20.
Specific heat capacity of gadolinium-scandium-gallium and calcium-niobium-gallium garnets

D.A. Samoshkin, S.V. Stankus
Kutateladze Institute of Thermophysics SB RAS, Novosibirsk, Russia
Keywords: gadolinium-scandium and calcium-niobium gallium garnets, specific heat, differential scanning calorimetry

Abstract >>
An experimental study of the specific heat capacity of gadolinium-scandium-gallium and calcium-niobium-gallium garnets widely used in laser technology and microelectronics was carried out by the method of differential scanning calorimetry. New experimental results on the specific isobaric heat capacity in the temperature range of 300 -1270 K were obtained; approximation equations and a table of recommended values for scientific and practical use were developed on their basis. The comparison with the known literature data was carried out. The estimated error of the data obtained was 2-4%.



21.
Study of n-heptane combustion being sprayed with superheated steam and at different excess air ratios in the gas generation chamber

I.S. Sadkin1,2, E.P. Kopyev3, E.Yu. Shadrin3
1Kutateladze Institute of Thermophysics SB RAS, Novosibirsk,Russia
2Novosibirsk State Technical University, Novosibirsk,Russia
3Kutateladze Institute of Thermophysics SB RAS, Novosibirsk ,Russia
Keywords: liquid hydrocarbons, combustion, superheated steam, reduction of nitrogen oxide emissions, combustion completeness

Abstract >>
Combustion of liquid hydrocarbons sprayed with a jet of superheated steam is experimentally studied using n-heptane as an example as a promising method for efficient and environmentally safe combustion. with forced air supply to the gas generation chamber. It is a modernized design of an atmospheric burner with a natural air inflow, studied by the authors earlier, and it allows obtaining additional information about the effect of changing the excess air ratio inside the device on the process of burning liquid fuel in the presence of superheated steam. New data on the environmental and energy characteristics of the burner under study were obtained based on thermocouple measurements, gas analysis of intermediate flame components, measurements of combustion efficiency and harmful emissions in the final combustion products. They were compared with characteristics of the burner with natural air inflow. It was found that formation of carbon monoxide during the combustion of heptane is reduced by 25%, and formation of nitrogen is reduced oxides by 15% with a decrease in the excess air ratio in the combustion chamber from 0.7 to 0.16. At the same time, a burner with a natural air inflow is characterized by a higher flame temperature and a shorter flame length. At that, the level of CO and NOx emissions in all regimes corresponds to the European standard EN 267. It was determined that the forced air flow does not have a noticeable effect on the heat generated for the studied regimes, and the calorific value of fuel combustion in all cases is close to the higher calorific value of heptane, which indicates the high efficiency of the combustion method under study.



22.
Experimental study of the flow turbulent structure in a cell of a lattice matrix

A.V. Zolotukhin1,2, I.A. Chokhar1, V.I. Terekhov1,2
1Kutateladze Institute of Thermophysics SB RAS, Novosibirsk,Russia
2Novosibirsk State Technical University, Novosibirsk,Russia
Keywords: lattice matrix, coplanar channels, rib crossing angle, aerodynamics, profiles of velocity and turbulent pulsations, hydraulic losses

Abstract >>
The experimental results on the turbulent flow structure in a lattice matrix cell, which is a region between intersecting ribs on the opposite walls of a flat channel, are presented. The angle between the ribs was 2β = 60º, 90º and 120º; the Reynolds number calculated from the average velocity and hydraulic diameter of the channel was varied in the range Re = (1 - 7)×104. The aerodynamic characteristics of the flow inside a lattice matrix cell placed in a rectangular channel with a cross-section of 20 × 150 mm and a length of 400 mm were measured using a two-component laser Doppler anemometer (LDA). The flow structure was studied in individual cells of 15 × 15 mm, formed by crossing ribs on the opposite channel walls. The complex three-dimensional structure of the flow in the matrix cells and strong turbulence of the flow in the near-wall regions are shown. The installation of ribs leads to a significant increase in hydraulic losses, especially at large crossing angles.