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2023 year, number 1
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A.V. Voevodin, A.A. Efremov, V.G. Sudakov
Zhukovskii Central Aerohydrodynamic Institute, Zhukovskii, Russia
Keywords: aerodynamics, civil aircraft, large angles of attack, rotation
Abstract >>
A numerical and experimental study of the flow near a standard civil-aircraft model at large angles of attack in the range from 0 to 90° and at subsonic velocities of the oncoming flow has been carried out. The experiments were performed in the T-105 wind tunnel of TsAGI. The calculations were carried out within the framework of solving the Reynolds equations. A comparison of the calculated and experimental integral characteristics showed a good agreement with an accuracy sufficient for practice. Physical features of the flow and their influence on the aerodynamic characteristics of a stationary model at large angles of attack, as well as in the mode of rotation of the model with a constant angular velocity, are revealed.
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T.A. Gimon, V.A. Kislovskii, S.V. Lukashevich, S.O. Morozov, M.S. Nikolaev, A.N. Shiplyuk
Khristianovich Institute of Theoretical and Applied Mechanics SB RAS, Novosibirsk, Russia
Keywords: compressible boundary layer, laminar-turbulent transition, linear theory of stability, Gortler vortices, direct numerical simulation
Abstract >>
The generation and development of Görtler vortices in a compressible boundary layer on a concave surface has been numerically modeled. The calculation was carried out using the Fluent software of the Ansys program package. Stationary and non-stationary perturbations are analyzed at oncoming-flow Mach number M ≈ 4. It is shown that when a periodic disturbance in the direction transversal to the flow is introduced, it decays on the straight section of the surface, and grows on the concave surface. Comparison of the results of the calculations made with the calculations performed within the framework of the linear theory of stability showed that the range of susceptibility of the boundary layer to disturbances on the concave surface amounts approximately to 17 boundary-layer thicknesses. After the susceptibility zone, disturbances grow exponentially with small deviations. The flow fluctuation profiles are in good agreement with the data obtained from the linear theory of stability. It is shown that the development of a non-stationary perturbation along the surface of the model for the parameters considered in the present study differs little from that of a stationary perturbation.
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V.E. Zhukov, A.N. Pavlenko, E.Yu. Sukhorukova, A.N. Chernyavskiy
Kutateladze Institute of Thermophysics SB RAS, Novosibirsk, Russia
Keywords: distillation column, structured packing, anemometer
Abstract >>
Data of experimental studies on hydrodynamics of countercurrent flows of liquid and vapor in distillation columns with structured packings are necessary for verification of computational models that describe hydrodynamics and processes of heat and mass transfer in industrial distillation columns. The paper presents a description of the design of a multipoint hot-wire anemometer with a coordinate device, developed to measure the steam flow rate under conditions of jet irrigation of the packing with a countercurrent flow of freon mixture phases. The measurement system was tested with air flowing through a 210-mm layer of Sulzer 500X structured packing. The measurements were carried out using a large-scale research model of a distillation column with a diameter of 900 mm. Experimental data were obtained on the distribution of the local air flow velocity at the outlet of a single-layer Sulzer 500X packing. Scanning the packing plug with a step of 1 and 5 mm showed the presence of a periodic cellular pattern of the gas flow velocity distribution, which correlates with the structure of the studied packing.
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A.V. Kashkovsky, A.N. Kudryavtsev, A.A. Shershnev
Khristianovich Institute of Theoretical and Applied Mechanics SB RAS, Novosibirsk, Russia
Keywords: supersonic non-isobaric jets, shock-wave structure, axisymmetric flow, rarefied gas, Direct Simulation Monte Carlo method
Abstract >>
The Direct Simulation Monte Carlo (DSMC) method is used to study rarefaction effects on the structure of an axisymmetric underexpanded jet. A comparison with the data of other researchers shows that DSMC simulations accurately reproduce the features of the steady shock-wave structure of the jet. Rarefaction produces a noticeable effect on the jet flow. In particular, it makes the barrel shock in the first shock cell change the type of its reflection from the axis, which leads to vanishing of the developed Mach disk and to changes in the structure of other shock cells. For the first time, the formation of a closed reverse flow region behind the Mach disk is observed in a molecular-kinetic simulation. This phenomenon has been earlier observed only in continuum simulations.
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A.V. Minakov1,2, D.V. Platonov1,2, A.V. Sentyabov1,2
1Kutateladze Institute of Thermophysics SB RAS, Novosibirsk, Russia
2Siberian Federal University, Krasnoyarsk, Russia
Keywords: pressure pulsations, Francis turbine, re-connection, modeling, hydroelectric power station
Abstract >>
The influence of asymmetric boundary conditions on flow regimes in a model hydraulic turbine has been investigated. The curved draft tube is shown to have almost no effect on the vortex structure, preserving such a phenomenon as the re-connection of the vortex core. The axial and tangential velocity profiles also remain unchanged. There is a change in pressure pulsations, despite the similarity of the average values and the unsteady vortex flow pattern. In the case of an asymmetric model, the pressure pulsation is higher than for a symmetric model. This may indicate a superposition of pulsations, caused by the rotation of a precessing vortex core, with generated longitudinal (synchronous) pressure fluctuations.
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V.V. Markin, P.A. Polivanov, G.A. Berkon
Khristianovich Institute of Theoretical and Applied Mechanics SB RAS, Novosibirsk, Russia
Keywords: propeller, multirotor aircraft, small Reynolds numbers, thermal anemometry
Abstract >>
The paper presents the research into small multirotor vehicles that fly in the surface layer of the atmosphere, where the level of flow disturbances impinging on the blade can change significantly, altering the characteristics of the propeller. Axial streamlining of a constant-pitch two-blade rotor with a diameter of 380 mm was experimentally studied in a low-noise wind tunnel T-324 of ITAM SB RAS. The experiment was carried out in the range of Reynolds numbers up to 1.5∙105, calculated from the flow parameters in the cross section of 75% of the rotor radius. The thermoanemometric method was used as the main measurement method. The influence of pulsations of the incoming flow on the flow characteristics in the propeller wake was established.
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J. Cai, C. Wang, Y. Hu
Guangdong University of Technology, Guangdong, China
Keywords: ionic wind, numerical simulation, heat sink, optimization
Abstract >>
In this paper, the characteristics of the electric field, flow field and temperature field of ionic wind heat sink are studied, respectively. The results show that the heat sink achieves the best performance when the ratio of fin spacing to thickness is 5, the electrode spacing is 5mm, the needle position is 0. Furthermore, a two-stage structure ionic wind heat sink is proposed and optimized. The optimized average wind velocity increased by 30.8% to 3.57m/s compared to the single-stage structure. This work enriches the knowledge of electrode configuration and promote the application of ionic wind heat sinks.
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Yu.M. Prikhodko, V.P. Fommichev, V.P. Chekhov, A.E. Medvedev
Khristianovich Institute of Theoretical and Applied Mechanics SB RAS, Novosibirsk, Russia
Keywords: disk pump, friction machines, dimensionless parameters
Abstract >>
The operation of the centrifugal disk pump is experimentally studied. To summarize experimental data, dimensionless parameters are introduced. A method for calculating the flow rate, pressure, and throttle characteristics is proposed. The method ensures accuracy sufficient fort engineering calculations.
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S.A. Isaev1,2
1State Marine Technical University of St.Petersburg, St-Petersburg, Russia
2Saint Petersburg State University of Civil Aviation, St-Petersburg, Russia
Keywords: heat transfer enhancement, vortex, inclined groove, plate, narrow channel, numerical simulation, experiment
Abstract >>
The RANS approach was used for revealing the phenomenon of interference of a jet flow while deceleration due to interaction with the windward edge of the inclined groove on a streamlined plate and the narrow trench wall; the interaction generates a tornado-like vortex at the groove inlet. Experiments confirmed emerging of extra-ordinary drops in static pressure between the stagnation and rarefaction zones. The return flow velocity increases twice and this velocity magnitude exceeds the superficial velocity. The study justified the separation flow increase and heat transfer enhancement for the cases of inclined grooves on a structured surface. This effect is related with a multiple (up to 6-9 times) growth of relative friction and heat fluxes inside the grooves (compared to the case of a flat wall). We observe also acceleration in the near-wall stream caused by a set of single-row inclined groves in a narrow channel. Here the maximum velocity in the stream core in a structured channel increases by more than 1.5 times as compared the maximal velocity for a flow in a planar-parallel channel. The study performs aerodynamic disigning of new energy-efficient grooves-structures surfaces.
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S.V. Alekseenko1, P.A. Shchinnikov2, I.S. Sadkin1,2
1Kutateladze Institute of Thermophysics SB RA, Novosibirsk, Russia
2Novosibirsk State Technical University, Novosibirsk, Russia
Keywords: carbon dioxide power cycles, CO cycle, supercritical carbon dioxide, decarbonization, zero emissions
Abstract >>
Four options for the power cycle using carbon dioxide as a working fluid during oxygen combustion of gaseous fuel are considered. In all the cases, heat is supplied in the zone of supercritical parameters of CO2. The fundamental difference in options lies in the method of increasing the working fluid pressure. The heat is supplied to the cycle in the combustion chamber, and the cycle operation is accompanied by continuous updating of the working fluid, since part of CO2 and all steam obtained during fuel combustion are removed from the cycle. It is shown that cycles with a single-stage pump pressure increase have the highest thermal efficiency, reaching 64.5%. The effect of thermodynamic parameters on the energy characteristics of cycles has been estimated quantitatively.
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V.A. Kosyakov1,2, R.V. Fursenko1, A.N. Shiplyuk1
1Khristianovich Institute of Theoretical and Applied Mechanics SB RAS, Novosibirsk, Russia
2Novosibirsk State Technical University, Novosibirsk, Russia
Keywords: hybrid rocket engine, computational fluid dynamics, combustion of gas-droplet fluid, diffusion flame
Abstract >>
Results of numerical simulation of the combustion of a gas-droplet fuel mixture in an oxidizer flow under conditions typical of hybrid rocket engines are reported. The effect of the size and rate of supply of fuel droplets on the combustion completeness, temperature and position of the diffusion flame in the boundary layer of the oxidizer flow has been studied. It is shown that the influence due to the liquid fuel droplets manifests itself as a local decrease of gas temperature and an increase of the concentration of the gaseous fuel in the immediate vicinity of droplets. The addition of droplets to the gaseous fuel flow results in a slight decrease of the flame thickness and flame temperature, which, however, experience no large-scale perturbations as a result of droplet movement and remain almost stationary.
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I.S. Sadkin1,2, E.P. Kopyev1, E.Yu. Shadrin1, M.A. Mukhina1
1Kutateladze Institute of Thermophysics SB RAS, Novosibirsk, Russia
2Novosibirsk State Technical University, Novosibirsk, Russia
Keywords: liquid hydrocarbons, combustion, superheated steam, carbon dioxide, reduction of nitrogen oxide emissions, combustion efficiency
Abstract >>
Combustion of liquid hydrocarbons by spraying them with a jet of superheated steam, carbon dioxide and air has been experimentally studied. Results aimed at identifying the advantages of using superheated steam as a diluent sprayer over other diluent gases were obtained at the example of diesel fuel. For this, thermocouple measurement data were studied and compared, gas analysis of intermediate flame components was performed when fuel was sprayed with various diluent atomizers, and both combustion efficiency and harmful emissions in the final combustion products were compared. It was found that the air spray regime has a higher flame temperature (~ 150°С) in the entire measured range as compared to steam and carbon dioxide spray. At the same time, the regimes with steam and carbon dioxide have similar temperature profiles. Exhaust gas analysis showed that when sprayed with steam, the reduction in NOx reaches 25 and 70% relative to carbon dioxide and air, respectively, which makes its use as a diluent atomizer more preferable when burning liquid fuels as compared to other studied gases.
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V.O. Zuev1,2, S.V. Dvoinishnikov1, V.G. Meledin1, V.V. Rakhmanov1, O.Yu. Sadbakov1, I.K. Kabardin1
1Kutateladze Institute of Thermophysics SB RAS, Novosibirsk, Russia
2Novosibirsk State University, Novosibirsk, Russia
Keywords: ice, phase triangulation, refraction of optical signals
Abstract >>
The research was devoted to the problem of measuring geometric parameters of ice by the method of phase triangulation in a limited volume with refraction of optical signals. This method served to develop an algorithm of measurement and calibration. It was also expedient to take into account the reflective properties of ice and the conditions of external lighting, as well as to ensure a minimum error in measuring the geometric parameters of ice. For this purpose, software complexes to control the quality of the measuring system with current parameters and to calculate the geometric parameters of ice, as well as a software and hardware complex for measuring the geometric parameters of ice by the phase triangulation method in a limited volume with refraction of optical signals have been developed. The measuring system was configured for a measuring volume with characteristic dimensions (100×100×60) mm. A measurement error of 12 microns has been achieved. Experiments were carried out to measure the geometric parameters of ice formed on a cylindrical surface. The values of the local thickness of the ice and the statistical value of the thickness of 1.6 mm have been restored. The developed technologies may be used in experiments on an aerodynamic stand for the study of icing processes aimed at creating anti-icing methods in various fields of industry.
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A.B. Kruglov, I.I. Konovalov, B.A. Tarasov, V.S. Kharitonov, L.P. Paredes
National Research Nuclear University (MEPhI), Moscow, Russia
Keywords: heat-conducting liquid metal sublayer, pulse heating method, thermal conductivity of lead-sodium and bismuth alloys
Abstract >>
The article presents the results of measurements of thermal conductivity coefficients of Pb-Na with the content of the latter of 20 at. % and eutectic (Pb-Bi)-Na 20 at % alloys at temperatures of 350 - 800 °С. The experimental methodology is described and the temperature differences in the heat-conducting sublayer of fuel cells of the studied alloys are estimated.
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R.N. Abdullaev, R.A. Khairulin, S.V. Stankus
Kutateladze Institute of Thermophysics SB RAS, Novosibirsk, Russia
Keywords: gamma method, density, thermal expansion, melt, lithium fluoride, sodium fluoride
Abstract >>
The density of liquid lithium fluoride and an eutectic mixture of lithium fluoride and sodium fluoride (with a content of 39 mol. % NaF) was measured by the gamma ray method in the temperature range from liquidus to ~1280 K. The obtained results were compared with the available literature data. The study of liquid eutectic LiF - NaF was carried out in a significantly wider temperature range compared to other authors, and the obtained values of the volumetric coefficient of thermal expansion turned out to be the most reliable.
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P.P. Bezverkhii1, O.S. Dutova2
1Nikolaev Institute of Inorganic Chemistry SB RAS, Novosibirsk, Russia
2Kutateladze Institute of Thermophysics SB RAS, Novosibirsk, Russia
Keywords: methane, combined equation of state, critical point, heat capacities, speed of sound
Abstract >>
A new thermal equation of state for methane is proposed in explicit form, including a crossover function. This function comprises new regular and scaling parts with 22 adjustable coefficients written in real temperature-density variables. The coefficients are determined from the ρ, ρ, T-data for CH4. Data on the heat capacities Cv, Cp and the speed of sound W were not involved in calculations, except for the data on the isochoric heat capacity Cv in the ideal gas state and the Cv value at 100 K on the liquid branch of the liquid-gas equilibrium curve. In the regular region, the calculated values of Cv, Cp, and W are close to the experimental and tabulated values. In the critical region, the discrepancies with the tabulated values are no more than 5%, which is associated with the use of the scaling equation of state. The average absolute deviation is 0.3% in the pressure description, the r.m.s. error σp = 0,5 %, and the error in Cv is less than 5%. The calculation results are compared with the known crossover equations of state for CH4. It is concluded that the proposed model of the equation of state is preferable for calculating the thermophysical properties of methane.
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A.A. Chernov1,2, M.N. Davydov1,3, A.A. Pil’nik1,2
1Novosibirsk State University, Novosibirsk, Russia
2Kutateladze Institute of Thermophysics SB RAS, Novosibirsk, Russia
3Lavrentyev Institute of Hydrodynamics SB RAS, Novosibirsk, Russia
Keywords: gas-saturated liquid, gas bubble, decompression, degassing, boundary value problem with a moving boundary, numerical simulation, magmatic melt
Abstract >>
Dynamics of gas bubble growth in a highly viscous gas-saturated liquid (magmatic melt) subjected to decompression is investigated. A mathematical model of the process, which is a joint dynamic and diffusion problem, is proposed. An approximate semi-analytical solution is found based on the existence of a quasi-stationary state for the bubble growth process. The influence of certain factors on the process under consideration at all its stages is shown. In particular, a significant dependence of the bubble growth rate on the decompression rate is illustrated. It is shown that, at long times, bubble growth has a self-similar character and occurs only as a result of gas desorption from the surrounding liquid.
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V.N. Popov
Khristianovich Institute of Theoretical and Applied Mechanics SB RAS, Novosibirsk, Russia
Keywords: numerical simulation, modification, spherical nanoparticles, heterogeneous nucleation, crystallization, aluminum alloy
Abstract >>
The paper considers a model of nucleation of crystal phase during cooling of a modified melt below the liquidus point. We demonstrated a connection between the overcooling factor, nucleus size forming at the particle surface, and the amount of consumed energy. Numerical simulation was performed for solidification of a modified bicomponent aluminum melt in a cylindrical crucible with account for thermodynamics, heterogeneous nucleation and crystallization. We found the conditions of crystal nuclei formations: both for the cases with the size higher or smaller that the size of seeds. It was shown that efficient modification of the metal needs the use of powders with maximally homogeneous size. The reliability of this model is confirmed by reasonable compliance between the simulation and physical experimental data.
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V.A. Serikov1, P.V. Domarov1,2, M.V. Cherednichenko1, V.S. Cherednichenko1
1Novosibirsk State Technical University, Novosibirsk, Russia
2Kutateladze Institute of Thermophysics SB RAS, Novosibirsk, Russia
Keywords: hollow cathode, thermal field, thermal losses, cathode region, vacuum plasma torch
Abstract >>
The paper presents the results of the main physical processes that ensure the operation of hollow cathodes of vacuum plasma torches with the formation of high-enthalpy plasma inside the cavity. The interaction of the plasma with the inner surface of the cathode determines the temperature field of the hollow cathode and the distribution of heat fluxes in the vacuum discharge. The formation of the temperature field in the cathode body, in addition to temperature processes, is significantly influenced by the conditions of heat exchange between the cathode and the environment, the characteristics of the cathode material and its geometric dimensions. Studies of plasma emission spectra in the cathode cavity have shown that the appearance of spectrum lines depends on the excitation conditions and determines the energy limits of electrons accelerated in the cathode layer.
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V.E. Messerle1,2,3, A.B. Ustimenko1,3, M.K. Bodykbaeva3
1Institute of Combustion Problems, Almaty, Kazakhstan
2Kutateladze Institute of Thermophysics SB RAS, Novosibirsk, Russia
3Al-Farabi Kazakh National University, Almaty, Kazakhstan
Keywords: waste, plasma gasification, synthesis gas, thermodynamic calculation
Abstract >>
The paper presents the results of thermodynamic calculations and experimental studies of plasma processing of biomedical waste and fuel biomass, including waste from the woodworking industry and agriculture, which have shown the promise of using plasma-chemical technology for processing various wastes with production of combustible gas and inert mineral material. Comparison of the experimental results and calculations showed their satisfactory agreement. Both in calculations and in experiments, no harmful impurities were found in the products of plasma processing of the investigated wastes.
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Abstract >>
On November 30, 2022, an outstanding scientist in the field of thermal physics and thermal power engineering, Doctor of Technical Sciences, Professor, Academician of the Russian Academy of Sciences Alexander I. Leontiev passed away.
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