Scientific results:
New data has been obtained on heat exchange in a model substance imitating molten salts.
Our researchers have produced a refined version of the WALE model similar to the one proposed in the work by Laurent Bricteux et. al. («Physics of fluid», 2009). Test computations were obtained for stabilized flow in a channel with the WALE and Smagorinsky subgrid viscosity models, which demonstrated the advantage of the Smagorinsky model.
The original ANES software has been amended with a two-parameter Launder–Sharma model and a two-dimensional k–ε model for low Reynolds numbers. A series of test computations confirmed the feasibility of the model. In application to the development of the LES method we have implemented the WALE subgrid turbulence model. We developed an algorithm and software for forming a layer of filling comprised of spheres of the same size with random structures. In this algorithm we modeled a system of N elastic spheres poured into a specified container (tube, cube). As a result, we received a geometry with characteristics (porousness, distribution of porousness across the volume), close to those of a freely poured layer. Verification demonstrated that the degraded regime of heat exchange describes only the k–ε Launder–Sharma model that was used for further modeling. Modeling experiments without a magnetic field showed a significant difference between experimental and computational data on temperature fields on the measured region (20 calibers from the beginning of the heating).
We described a technology of plasma-beam processing of materials. We developed design documentations for the nodes of a plasma-beam processing device (PBPD) and the device as a whole. We finished the assembly of vacuum system of the PBPD. The vacuum system was launched into operation, ensured its design parameters. The magnetic system of the PBPD was created. A magnetic field was produced, a linear system, 8-pole multicusp. The magnetic field is longitudinal along an axis from 2 mТ to 6 mT. The plasma discharge power supply system was created. We finished designing the cathode node of the PBPS.
New data has been obtained on the viscosity of a model molten salt compound – KOH solution – in concentrations ranging from 0 to 40% and in the temperature range from 20 to 60 °C.
A methodology has been developed for researching the electric and thermal conductivity of a model substance. The foundations of a model of mass and energy transfer in an irregular medium have been developed, substantiating the previously inferred fractal differential equation of diffusion with variable derivative order. The obtained results are intended both for describing ion diffusion in liquid and for applications in the mathematical model of heat transfer in media with complex internal structures.
For the first time we have obtained comprehensive data on averaged temperature fields, intensities of temperature pulsations, the wall temperature, the statistical characteristics of temperature pulsations in an ascending or descending flow of liquid metal (mercury) in a rectangular channel in a coplanar magnetic field during symmetrical heating in a wide range of regime parameters (Re, Ha, Gr). For the first time we proposed an algebraic model of turbulence suppression by a coplanar magnetic field under minor influence of thermogravitational convection. We found analogy between the degree of suppression of turbulent transfer by a coplanar field in a rectangular channel and a transverse field in a round pipe.
We have developed and manufactured modified measurement probes with a spherical hinge. The probes can be used for researching the characteristics of the hydrodynamics and heat transfer in flows of liquid metal (lead, mercury and others), molten salts as well as model liquids.
New data has been obtained from research of the thermal conductivity of metal processed using plasma. The obtained results indicate a change in the coefficient of thermal conductivity determined using the laser flash method. An array of experimental data on the electrical conductivity coefficient has been accumulated and approximated with a polynomial law of temperature and electric field strength and frequency. The approximation error was 2.5%.
For the first time we have conducted experiments and obtained new results of research of flow of liquid metal in a heated channel under the influence of a transverse magnetic field directed along the wide part of the channel during ascending flow in which the buoyancy forces are oriented in the same direction as the flow of metal. The experiments extend the results on descending flows obtained earlier. Two heating regimes were investigated: a channel heated on one side and a channel heated on both long sides. These two heating regimes demonstrate a significant difference in the behavior of the flow, which leads to various dependencies of heat transfer on control pulses (flux rate – the Péclet number (Pe), magnetic field – the Hartmann number (Ha), heating indicator – the Grashof number (Gr)).
We demonstrated that the orientation of the channel and the heating regime significantly influences heat exchange without a magnetic field. In the case of two-side heating, the Nusselt number experimentally observed in an ascending flow decreases in comparison with a descending flow. For one-side heating with an ascending flow the experiments demonstrated that heat exchange decreases as the speed of flow increases in the range 200 < Pe < 1000 (increasing at Pe >1000), while in a one-side descending flow the Nusselt number increases as the Péclet number increases, which is normal for a turbulent flow. In an ascending flow this strong difference in heat transfer is caused by the buoyancy forces that change the temperature gradient in the near-wall region.
In contrast to descending flows, in the course of our research we found a very weak dependence of heat transfer on the magnetic field, i. e. in an ascending flow of liquid metal heat transfer is ensured mainly by the structure of the mean flow (the mean velocity profile) and not by small-scale turbulent transport. The suppression and transformation of turbulence by a magnetic field was observed in the form of a narrowing spectrum of temperature fluctuations without the development of large-scale temperature fluctuations. The experiments were conducted in a channel with a length of about 20 calibers. It was found that the stabilization of the flow is delayed by the magnetic field to the full length of the studied channel, therefor the length of the channel turned out to be insufficient to observe a completely developed flow, i. .e. the intensity of temperature fluctuations continued to change toward the outlet of the channel in the majority of the reviewed flow regimes. However, the reviewed length of channels corresponds to designs of various devices in which finite-length channels will be used, while the observed temperature fluctuations insignificantly affect the heat exchange. Nevertheless, we can suggest that the effects of input and output (heating and the relative distribution of the magnetic field, the inhomogeneous distribution of the magnetic field) can have a decisive importance, and hence further research of flow stabilization is highly important.
In the researched modes there were no stationary reverse flows, the possibility of which is predicted by laminar analytical solutions or numerical modeling. A flow supplemented by the buoyancy forces continues preserving a wide range of pulsations even in a moderate magnetic field that is sufficient to completely suppress isothermal turbulence.
For the first time we have obtained new data of measurements of the profiles of the averaged temperature and intensity of temperature pulsations along a channel of complex shape at various distances from the distancing insert. It was demonstrated that the turbulizing role of the insert does not lead to a dangerous increase in temperature pulsations. In tests involving mercury in a magnetic field we confirmed that in all MHD configurations heat exchange is significantly influenced by thermogravitational convection, up to emergency heat exchange regimes.
For the first time, initially using experimental research and then by numerical modeling, we found the boundaries of occurrence and suppression of abnormal temperature pulsations during flow of liquid metal in a vertical pipe under conditions of inhomogeneous heating in an extended range of dimensional similarity criteria. We experimentally researched the specifics of the interaction of electromagnetic force and thermogravitational convection during MHD heat transfer in liquid metal. New data was compared with data collected earlier using another testing bench and is confirmed by direct numerical modeling.
Suppression of disturbances by a strong magnetic field, depending on the value of the Gr, Ha and Re numbers, either stabilizes jets heated near walls or delays their destruction up to very high velocities, which leads to disturbances of abnormal type with very high amplitude. This can lead to problems of integrity of structures of heat exchange system, which is related to high-amplitude thermal strains imposed on channel walls.
Using the PBPD we obtained new data from experiments on plasma irradiation of wolfram of various marks (for up to 200 minutes) in a helium discharge, including the ITER make used for the manufacturing of the divertor of the ITER thermonuclear reactor. On all the samples we achieved conditions of modification of the nano- and microstructure of the surface down to a depth of several dozen microns. At the surface of wolfram samples under conditions of the surface being heated up to 970 °С and irradiated by helium plasma for up to 100 minutes a nanostructured surface of the «fluff» type with a thickness of up to 1.6 micron is formed. The coating consists of nanofibers with a diameter of 20–50 nanometers. Changes in the nanostructure of the surface were also found when titanium and iron samples are irradiated with plasma for long time periods, which can testify to the universality of the mechanism of growth of a nanostructure of the «fluff» type. During a research of the thermal conductivity of a wolfram surface with a structure of the «fluff» type, we found a decrease in thermal conductivity.
As a result, we obtained new data from: a research of materials under powerful plasma loads in the PBPD for the creation of a porous nanostructured wolfram surface; a research of heat exchange and methods of its intensification in heavy-duty elements of thermonuclear reactors; a research of plasma irradiation of titanium and iron for the understanding of the mechanisms of changes in the nano- and microstructure of the surface under long-term powerful plasma loads exceeding 1 MW/m2; a microscopic and spectral research of the properties of construction materials of a thermonuclear reactor after tests in the PBPD and experiments involving powerful beams.
For the first time we have tested a capillary-pore systems (CPS) made of liquid metal lithium and liquid metal tin in stationary plasma in the PBPD plasma device (PLM) where the parameters of plasma correspond to the divertor and peripheral plasma of the tokamak. The CPS contained tin and lithium bars fixed between two molybdenum lattices installed in the module directed towards plasma. Exposure to a stationary plasma load of 0,1 to 1 MW/m2 on CPS for more than 200 minutes was achieved in experiments with plasma parameters corresponding to the remote near-wall plasma and the remote zone of the divertor plasma of a large tokamak and a tokamak thermonuclear reactor. Exposure to a plasma load of up to 1 MW/m2 lead to the surface being heated to 700°С in an experiment with a lithium CPS and more than 600°С in an experiment with a tin CPS. The heating of the CPS was controlled remotely, including by supplying current to the CPS, which allows to control the influx of vaporized metal into the plasma. Under such a load, liquid metal from the surface of the CPS into the plasma column. After the exposure, the materials of the lithium and tin CPS were checked and analyzed using optical and scanning electron microscopy. For the first time we studied the effect of lithium and tin vapor on plasma/radiation transport using spectroscopy to assess the changes of the properties of plasma and the interaction of the plasma with the surface. Lithium and tin ions were registered according to the spectra of optical radiation from plasma. We found secondary deposition of vaporized lithium onto elements of the device located inside the chamber.
We have designed and installed the working area of the experimental device (test bench)for the research of cavitation in liquid metals. We developed and tested a system for diagnostics of a cavitating opaque liquid relying on the radiometric method. The main feature of the system is the use of low-activity gamma radiation sources.
Our researchers have developed computation software (a program for numerical modeling) that models water particles, to resolve the intermolecular interactions we used the SHAKE and RATTLE algorithm. The code was debugged in tests performed to determine the thermodynamic properties on the saturation–density line, the surface tension coefficient. The obtained computation data are in satisfactory agreement with NIST data. We obtained new data from modeling using the methods of molecular dynamics of the processes of contact between an argon droplet (with a radius of ~7 nm and an initial velocity of 10 m/s and an overheated surface of copper . As a result of the contact the size of the droplet decreased more than twice, the mean density of the mass flow was ~103 kg/m2s. A simple model has been developed and tested that uses parameters from the molecular dynamics, which is in good agreement with numerical experiments.
The Laboratory has developed an experimental device that allows to measure the surface tension of liquids using a high-speed video recording system. Pilot experiments on water demonstrated the feasibility of the used methodologies: the deviation of the measured surface tension coefficient from the reference value was less than 3%. We conducted a research of the spectrum of radiation of plasma of a high-voltage gas discharge near the surface of a liquid. We studied contracted and diffuse forms of the discharge, demonstrating the difference between their spectra.
We have developed and implemented in the CBL (Cut Boundary Layers) code a new model for the reduction of the number of cells, in which near the boundary of a channel or pipe a layer of unstructured hexagonal KO is formed. When modeling problems with solid walls, a region of the wall is «placed» into the CBL КО zone, which additionally allows to reduce the number of КО without losing those needed for turbulence scale resolution. In a number of problems the CBL approach allows to reduce the number of cells of the computation mesh by 40–50%. The first results of the experiments (DNS modeling of flow in the stabilized portion of the pipe) demonstrated the high efficiency of such an approach. We obtained new results from LES modeling of turbulent flow of water, air and mercury in a pipe in the «flow–solid wall» conjugate setting. The results of the modeling indicated that «conjugate» LES models are good at reproducing the temperature pulsations near the solid wall for various thicknesses of the walls and various levels their thermal activity. On the basis of the results of the modeling, we proposed an approximated nonstationary model that accounts for the effect of the wall on the temperature characteristics. The model can be reduced to a nonlinear nonstationary condition condition of the third kind. It does not require explicitly including the wall in the computed region and can be useful for conducting DNS modeling. We obtained new results of RANS modeling of flow of mercury (Pr = 0.024) in a horizontal heated pipe under a strong magnetic field with the regime parameters Rem = 104, Наm = 300 and Grm = (3.78…6.0) ×107. For this modeling we used a two-parameter k–⍵ model implemented using the ANES code. Due to its stationary setting, these computations do not allow to describe abnormal temperature pulsations found in the experiment and DNS modeling. However, comparing averaged temperature fields shows good agreement with data from the experiment. We studied the impact of the properties of the wall of a pipe on the velocity and temperature fields. This research demonstrated that the leading role is played not by the thermal conductivity of the pipe but by its electrical conductivity. The results for a wall with low electrical conductivity are practically identical to the results obtained in computations without a wall. Accounting for a electroconductive wall with an electrical conductivity close to the electrical conductivity of the liquid leads to a significant change of the velocity profile and a decrease in the intensity of turbulent transport. This, in turn, leads to a better coincidence between the computed and experimental pipe wall temperature profiles.
The Laboratory has obtained new results of experimental research of magnetic convective pulsation (MCP) in a descending flow of liquid metal in a vertical inhomogeneously heated pipe under the influence of a transverse magnetic field. Such a configuration is typical for elements of the modules of the blanket of a thermonuclear reactor, in which thermal load is applied to one side in the direction perpendicular to the magnetic field. We determined the region of the existence of regimes characterized by a strong MCPs in the range of Stuart–Richardson parameters and low inverse Reynolds numbers (determined along the Hartmann axis) – Richardson numbers. This region of the existence of MCPs is bounded by three limits. The lower bound of buoyancy is determined by the critical Richardson number Rimin ≈ 0.08, which indicates the value of required buoyancy for MCPs to manifest themselves, moreover, this boundary does not depend on the magnetic field. The lower boundary of the magnetic field is determined by the critical Stuart number Nmin≈1.5. This boundary indicates the value of magnetic field strength required to affect the developed turbulence and ensure the transition from homogeneous turbulence to MCPs, while this boundary does not depend on heating. The upper boundary of the magnetic field is the most important in application to tokamak reactors. It defines the boundary of suppression of MCPs by a strong magnetic field. The strength of the magnetic field required for MCP suppression depends on the velocity of the flow and on heating and is described more precisely via the Reynolds number (Rh) than by the Stuart number. If Ri exceeds Ri > Rimin, the right boundary of the plane (Rh-1, Ri) is restricted by the Ri=6/Rh line, which corresponds to =Gr/(6Re). As Ri increases further, the boundary tends to the upper limit Rh-1=2/25, i. e. =2/25Re, above which the magnetic field completely laminarizes the flow for any buoyancy forces. For the first time the obtained experimental data allowed to complete the localization of the region of the existence of MCPs in the space of the parameters of a turbulent liquid metal flow in a magnetic field and demonstrate that a sufficiently strong magnetic field can suppress pulsations created after the buoyancy forces as any heating is applied.
We have obtained new results of direct numerical modeling of descending flow of liquid metal in a homogeneously heated pipe placed in a transverse magnetic field. Variational computations allowed to cover the range of regime parameters that had been reproduced earlier in experiments. These results are qualitatively, and in many regimes qualitatively as well, in good agreement with the results of the experiment, which allows to use them for an in-depth study of the reviewed phenomena in the future. They confirm the significant nonstationarity and spatial inhomogeneity of the processes, which complicates physical analysis as, for example, to obtain reliable statistical characteristics, sufficiently long-term datasets are required for measuring and computing in time. Nevertheless, despite the limitations, the main laws of the processes are reproduced using results of numerical computations. As we observed in the experiment, in the considered configuration of flow with homogeneous heating of the pipe wall in a transverse magnetic field, a significant nonstationary «pulsating» current develops in the flow. The development of this current is fully defined by the ratio of the main dimensionless criteria – the Reynolds, Grashof and Hartmann numbers. Using numerical modeling, we have studied this phenomenon depending on the Hartmann number. In this case as the main investigated regimes we picked regimes that differ in the nature of the distribution of the intensity of temperature pulsations in the cross-section of a x/d=37 pipe. The obtained results confirmed the existence of two different regimes of the development of temperature pulsations, as well as the nature of the influence of the strength of the magnetic field. A new methodology has been developed for indirect electric heating with one-side heating of a model element of the wall of a thermonuclear reactor. The principle of operation of the developed heater relies on the use of high-frequency induction heating. Pilot experiments demonstrated the efficiency of the use of the developed heating element.
The Laboratory has developed a new structure of the operational sections, manufactured two work areas. We modernized the hydraulic circuit of the FRA–MPEI test bench for the research of the hydrodynamics and heat exchange in a model of a fuel rod array with micro-fuel rods. We calibrated chromel alumel thermocouples. We conducted experimental research to determine the loss of pressure, the hydraulic resistance coefficient and the heat transfer coefficient in flows of liquid in a cylindrical sphere packing with heat emission at the following regime parameters: р = (2÷6) MPa, G=(0,005 ÷ 0,5) kg/s, q = (10 ÷ 170) kW/m2.
We have developed methodologies and devices for measuring velocity and temperature within a closed volume of liquid with low, volume-averaged velocity that rely on simultaneous spot measurements in the volume of the liquid with the use of a large number of temperature detectors, which allows to obtain a spatial picture of the temperature fields and temperature pulsations, the autocorrelation functions and frequency spectra of the temperature pulsations, the spatial correlations between various points in the volume, the spatio-temporal correlations and estimates of local flow velocities using the correlation method. It also allows to to study the development of the said indicators over time.
New data of measurements of the characteristics of near-surface plasma has been obtained in experiments with a liquid metal coating on the wall in the form of a tin and lithium capillary-pore system of CPS in the PLM plasma device with helium plasma. We obtained results of an analysis of the coating of the wall on the characteristics of near-surface wall plasma. We obtained the results of an analysis of erosion in a tin CPS and a lithium CPS in experiments involving stationary plasma in the PLV plasma device.
New data, which has been obtained in a numerical modeling of the processes of free convection in a hemispherical cavern with a model melt under conditions corresponding to the experiments of the «COPRA» research program, demonstrated a satisfactory correspondence with experimental data. As a rule, some differences between computational and experimental data were observed in regimes with hardening/melting of a model melt. The indicated differences can be explained by the imperfection of the used model of melting and the uncertainty of the physical properties of the model melt that were used in numerical computations. As a whole, the conducted analysis of the experimental and computational data demonstrated that the ANES computation code and the mathematical models implemented using it allow to reproduce, with satisfactory precision, the processes of natural convection in a melt with internal heat emission at high Raleigh numbers that are characteristic of ТА. The results of the numerical research for the computed region in the form of a cylindrical layer heated from below and cooled on the side and top surfaces demonstrated, in particular, that the use of the known ratios for the Nusselt number on the side and top surfaces of the layer leads to a significant error. Similarly to the case of a computed region having a shape of hemispherical cavern, the results of computational research performed for a computed region shaped as a flat layer heated from below, demonstrated that the ANES computation code and the mathematical models used in it allow to numerically model and reproduce with satisfactory precision the processes of natural convection in a flat layer of melt at Raleigh numbers exceeding ~109.
The Laboratory has conducted a comprehensive research pursuant to an agreement with the «Science and innovations» organization (Rosatom – State Atomiс Energy Corporation) devoted to studying plasma shielding under arc and plasma-beam erosion of wolfram and lithium materials to ensure stationary operation of tokamak reactors.
We have conducted a research of the effect of liquid metal tin or lithium coating on the plasma-wall interaction in a thermonuclear reactor in model experiments with liquid metal tin and lithium CPS in the PLM (plasma linear multicusp) plasma device at Moscow Power Engineering Institute. The conducted microscopic research indicated the effect of changes in the microstructure and the vitrification of the surface of the walls of the container of a tin CPS under plasma radiation, which should be considered when designing liquid metal elements of the wall in a future thermonuclear reactor.
We have determined the characteristics of near-surface plasma in experiments with a liquid metal coating applied to the wall of a lithium capillary-pore structure based on performing experiments with a lithium CPS in helium plasma in the PLM device. We found that evaporated lithium shields the high plasma heat load. No molybdenum erosion zones were found in components of the CPS in a microscopic research. Using energy-dispersive X-ray spectroscopy, we conducted an element analysis of these materials sedimented on the surface of the CPS.
We have conducted experiments with a liquid metal tin CPS in the PLM plasma device, irradiation with stationary helium plasma was conducted for over 1,5 hours, which corresponds to times of the use of a tin CPS in a reactor. While conducting this experiment, in the optical plasma diagnostics system we used a collimator, which allowed to obtain spatial resolution of spectroscopy.
Our researchers have performed thermophysical computations and determined the main technical characteristics for the creation of a research liquid salt reactor (RLSR) to devise a new technology for the utilization of minor actinides in specialized liquid salt reactors-burners.
The Laboratory has prepared and conducted experiments to study the dynamics of jet flows of liquid metal in strong magnetic fields in reported configurations.
We have verified the results of numerical experiments. Modeling to verify our findings using existing experimental data ensured a higher level of detail and a broader scope of analysis of the structure of the flow that had been studied experimentally (a flat and a round jet in transverse or coplanar magnetic fields) and provided information that is in principle impossible to extract from the experiment, including the main mechanisms of the transformation of jets under the influence of a magnetic field. We analyzed the behavior of the statistical characteristics of flows that determine its nature. Simultaneously with field and numerical experiments, we performed a low-mode analysis. We assessed the applicability of the representative of low-mode reduced order models (ROM) based on proper orthogonal decomposition (POD) in application to the analysis of configurations in a horizontal jet flow in a channel with heating in a transverse magnetic field (so-called magnetoconvection).
Our researchers have conducted numerical experiments to model turbulent MHD flow in a setting conjugate with the wall using the LES method in pipes and channels with various orientations (vertical, horizontal). We conducted an analysis of the effect of the formation of thin oxide films or sediments with low electrical conductivity on the inner surface of a channel on the arising abnormally high temperature pulsations in mercury and the wall.
We have obtained final data on the high-temperature creep and destruction properties of the 15Х2NMFA-A pressure vessel steel, which is used to produce the pressure vessels of Russian RU VVER nuclear reactors. The collected data was determined as a result of setting and conducting experiments to study creep in special samples of this steel under conditions of creep in the temperature range from 900 to 1200 °C in an argon protective environment and in vacuum. Samples for the testing of this steel were manufactured from the pressure vessel of an unirradiated original VVER manufactured using the standard technology. We have performed a structural analysis of fragments of samples after testing, which indicated the peculiarities of the mechanisms of flow and destruction of steel during experiments.
The obtained testing data and the results of mathematical processing of experimental data are novel and allowed to build relations for strength parameters of the Larson–Miller type for the studied steel under conditions of high-temperature deformation and destruction as a result of creep. Such data are the basis for analyzing major emergencies on RU VVER.
We have completed a research and presented the results of a numerical study of the processes of heat and mass transfer in flow-through metal hydride reactor for hydrogen purification with inner ribbing in the «active» volume (the volume of the absorbent filling). To intensify heat exchange from the filling to the cooled/heated walls of the reactor, in this structure we used radial ribs made of various metals. We have performed an analysis of various designs of internal ribbing, the impact of the conditions of external cooling on the processes of heat and mass transfer in the reactor. The sensitivity of the results of computations to the accuracy of determination of the parameters of the mathematical model was checked. It has been demonstrated that with the use of internal ribbing and with correctly selected conditions of external cooling, the characteristics of the metal hydride hydrogen storage and purification system can be significantly improved. We came to a conclusion that the density of the ribbing (the number of the ribs) and the thermal conductivity of the material of the ribs significantly influence the efficiency of a proton reactor only when certain values of the coefficient of heat transfer to the cooling liquid are achieved at its outer wall.
The Laboratory has conducted a research of the process of the formation of a zone with an increased concentration of air during condensation of almost pure vapor in a bundle of 397 smooth horizontal pipes. The arrangement of the modeled pipe bundle fully reproduced the layout of the bundle of the D.H. McAllister experimental unit, in which air is removed through two perforated pipes located in the center of the bundle. We researched the processes of flow and condensation of almost pure vapor (with a mass fraction of air of 1.22 × 10‒3) at a pressure of 27.67 kPA and the velocity of horizontally directed flow of vapor before the pipe bundle amounting to 12.3 m/s. The numerical modeling was performed using the CFD model built earlier. The local characteristics of the processes of heat and mass transfer in the pipe bundle have been studied. The obtained data on the quasi-stationary location of the boundary of the zone with an increased air content («air pocket»), as well as the field of velocity of mixture and the mass fraction of air in the condenser. A significant non-stationary of processes in the «air pocket» zone was found, which leads to a significant change in the time of local values of heat flow density on the walls of the pipes.
The satisfactory agreement of the obtained results of computations of local characteristics of heat and mass transfer with experimental data from D. H. McAllister and the detection of the effects not found when models of a porous medium is used allow to recommend the developed CFD model for the optimization of the structure of designed condensation devices.
We have conducted a numerical modeling of the processes of condensation of saturated pentane vapor on a smooth horizontal cylinder using the VOF method in a 2D setting. To analyze the stability and accuracy of the VоF algorithm, we have reviewed the condensation regimes of stationary vapor as well as the regimes of descending flow of vapor with a minor velocity. The obtained results were compared to known theoretical and empirical trends. To substantiate the feasibility of the metal hydride hydrogen storage systems, we have performed a numerical modeling of this system with a passive air system for cooling. We verified models of free convection on the basis of available literature data. The obtained results for the charge times of non-ribbed system for various values of the pressure and temperature. We selected the optimal step of the ribs for two values of the ribbing coefficient.
Education and career development:
- One Doctor of Sciences and 8 Candidate of Sciences dissertations have been prepared and defended.
- We have prepared and staged the 3rd
international conference «fer and hydroand power engineering» (19–23 October 2023, Moscow), the 8th conference «Heat and mass transfer and hydrodynamics of swirl flows» (18–21 October 2021, Moscow).
- The leading scientist Pyotr G. Frick and the employee of the Laboratory Valentin G. Sviridov have compiled the textbook «Foundations of automation of thermophysical experiments» published by Moscow Power Engineering Insistent in 2019 (336 pages).
- The leading scientist taught a series of lectures for master’s degree students within the lecture course «Basics of statistical theory of turbulence» (2019).
Collaborations:
From 2019 to 2022 the Laboratory participated in an expert group (supervising the group «Task #1») to assess the integrity of the pressure vessels of nuclear reactors after major emergencies «Working Group on Analysis and Management of Accidents (WGAMA)»- «The Reactor Pressure pressure vessel Integrity Assessment for in-pressure vessel retention» (as part of the work of OECD/NEA https://www.oecd-nea.org/jcms/pl_23462/working-group-on-analysis-and-management-of-accidents-wgama).
