Simulating gas (vapor) outflow into a liquid Lezhnin, S I; Alekseev, M V; Vozhakov, I S ...
Journal of physics. Conference series,
11/2018, Letnik:
1105, Številka:
1
Journal Article
Recenzirano
Odprti dostop
In this paper, an axisymmetric problem of gas outflow from a pipe end to an area of high density (two-phase mixture) is considered. Simulation of the two-phase coolant outflow without phase ...transition is carried out using a two-velocity model, solved by the LCPFCT software package 1. Cross-verification is performed with the results of calculation obtained by the OpenFoam software 2 using the VOF method for the approximation of the single-velocity model of a two-phase compressible medium. Using various numerical programs and various physical models of a two-phase medium gives a more complete understanding of the occurring processes.
Accelerators are used in many areas of modern science and technology (FCC-ee, CEPC, ILC, ESS, MYRRHA, etc.). One of the main elements of accelerators is the superconducting cavity based on ...high-purity niobium sheets. In addition to RRR requirements (over 300) niobium sheets for the SRF cavities should meet rather tough requirements for the grain size, recrystallization degree and mechanical properties. Development of the manufacture regimes of the niobium sheets with the required characteristics for the SRF cavities is a promising and relevant task. The paper presents the study results of the deformation route, true strain value, recrystallization heat treatment regimes influence on the structural and mechanical characteristics of the high-purity niobium sheets.
In the Kola River (Kola Peninsula), on the basis of cluster analysis of long-term density data in the nursery areas of underyearlings, wild and wild + hatchery parr of Atlantic salmon
Salmo salar
L., ...four clusters have been identified in each group of juveniles with high, medium, low, and very low density. In the lower and upper reaches of the river, areas were identified where the state of salmon reproduction can be assessed as critical. The article discusses the role of illegal, unreported, unregulated fishing, ulcerative dermal necrosis and hatchery reproduction as possible reasons for the decline in the reproductive potential of one of the most significant salmon rivers in the region.
The simulation of air injection into a liquid (water, liquid lead) at large pressure drops (ΔP = 160 × 105 Pa) has been carried out. A significant difference in the formation of the air volume during ...injection into water and liquid lead is demonstrated. The shape of the resulting air volume formed during injection into liquid lead is shown to depend on the nozzle diameter. It is established that the presence of interfacial heat transfer at short times does not affect the dynamics of the air jet outflow.
The required combination of performance properties for internal tin Nb3Sn wires for high energy physics includes high critical current density (Jc) and RRR values as well as low magnetization and ...effective diameters (Deff) value. It is quite a challenge to achieve them all at once. A comprehensive study has been carried out on two internal tin Nb3Sn wires with essentially different layouts and 37 sub-elements each. The first type of wires has distributed diffusion barriers. The second one has common diffusion barrier with sub-elements internally divided by resistive separators. Two sets of data for two types of wires have been obtained, which include transport measurements of Jc(B), magnetization loops M(B), superconducting transition temperature (Tc), RRR values, Sn-concentration by EDAX measurements and XRD analysis. XRD analysis of the superconducting layers has shown that the compressive macrostress is larger for the wire with overall barrier than for the wire with distributed diffusion barriers. This observation correlates with a shift of the stress-dependent curves of the superconducting transition. The difference in the volume fractions and the homogeneities of the Nb3Sn phase leads to a significant difference of the Jc(B) dependences and the values of the Kramer critical field (BKr) for these types of wires. In summary, the high critical current density for the first type of wires and the low hysteresis losses for the second type of wires have achieved with high RRR values in both cases.
The data on the evolution of the interface at the sudden injection of gas from a long tube into a liquid column was obtained. High speed video of experiments and calculations in OpenFoam software ...package were used as research methods. Investigations were performed for different initial pressures. Typical configurations of the interface for different time periods were shown both experimentally and numerically.
The texture of niobium in composite Nb
3
Sn superconductors prepared by internal-tin-source and bronze techniques, and in a subelement, which is required for fabricating the composite using the ...internal-tin-source technique, is studied in this work. It is shown that prior to the reaction heat treatment, the structural components of Nb have the (110) drawing texture; after the reaction heat treatment, no preferred orientation of Nb
3
Sn superconducting compound grains is observed.
The growing interest of developers of magnetic systems in strands based on the Nb
3
Sn superconducting compound with a high critical current density in magnetic fields above 12 T leads to the need to ...test various combinations of alloying elements in the superconducting layer. It also requires study of their effect on the microstructure and properties of this layer. Titanium and tantalum are the most commonly used alloying elements in the production of Nb
3
Sn-based superconductors. The effects of each of these elements on the electrical properties of Nb
3
Sn have been studied for many years. However, many questions remain about the combined effects of these elements. We study the features of the microstructure of two Nb
3
Sn-based strands with a diameter of 1 mm, which have the same design and titanium content, but with different tantalum contents: 4.0 and 7.5 wt %.
The results of a comparative analysis of the efficiency of the artificial reproduction of Atlantic salmon (
Salmo salar
) individuals released to the Kola River at ages of 3 years (1980–2002) and 1 ...year (2003–2017) are given. After the fish hatcheries began to release artificially reared anadromous salmon individuals at the age of 1 year, their qualitative parameters did not significantly change. The value of the commercial return became somewhat lower for the released yearlings than for the 3-year-old individuals; however, it remained satisfactorily high. It is recommended to reduce the release volume to avoid the overpopulation of juveniles; it is also suggested to evenly distribute them over the nursery grounds that are most suitable for their adaptation and select spawners for broodstock according to the historically established subpopulation structure.
The concentrations of Pb, Cd, Ni, Cu, and Zn were determined in the invasive pink salmon that came to spawn into the Kola and Tuloma rivers of the Kola Peninsula, flowing into the Barents Sea, in ...July 2019. The content of trace elements in the organs and tissues of pink salmon introduced in the Euro-Arctic waters of Russia was compared to those of the pink salmon from its native range, which returned to spawn in the rivers of the Sakhalin and Iturup islands in 2016–2018. It has been established that concentrations of Zn, Cu, and Ni noticeably predominate in all organs and tissues of introduced pink salmon, whereas Pb and Cd predominate in the Sea of Okhotsk pink salmon. Obviously, the differences in the microelement composition in fish are caused by environmental conditions. In the Barents Sea, they are formed under the influence of the Gulf Stream, as well as the anthropogenic impact of the Kola Peninsula, which is characterized by the extraction, processing, and smelting of a number of metals, primarily Ni and Cu, as well as Zn. In the Sakhalin-Kuril basin, the specificity of the environment and the microelement composition of salmon are due to the influence of natural factors—volcanism and upwellings. Schools of pink salmon during feeding and migration in the Pacific Ocean cross a high-nutrient and at the same time geochemically impact natural zone formed by the Kuril Ridge and the Kuril-Kamchatka Depression, which supplies chemical elements to surface waters. Here, the concentration of Pb is most markedly increased in fish. The development of the introduced pink salmon in the new area is facilitated by the recent increase in temperature in the waters of the North Atlantic, so the amount of fish production in it will increase. The mastering of pink salmon in new feeding places sets before scientists the task of monitoring the dynamics of its abundance and taking adequate measures for fishery regulation and fish quality control.
PDF
