The Shock-Wave Structure in a Gas−Particle Mixture with Chaotic Pressure

We consider the propagation of a shock wave in a mixture of a gas and fine solid particles with allowance for the difference in their velocities and the availability of the proper pressure of the phase of particles; here, equations of the Anderson type and others are used. We propose an approximate mathematical model of the flow; in this model, the dependence of the pressure of the first (gaseous) phase from the particles’ volume-concentration can be ignored, but the terms that present the phase volume-concentration multiplied by the pressure gradient of the gas are taken into account. It turns out that with this representation of the equation of state, the mathematical model has the hyperbolic type. For this system of equations of mechanics of heterogeneous media, we carry out the classification of the types of shock waves implemented in the considered mixture. The presented statements about the types are illustrated by numerical computations in stationary and nonstationary formulations; for this purpose, the numerical method of the TVD type is developed.     

An optimality criterion in a control problem for a Sobolev-type linear equation

The necessary and sufficient conditions for solving an optimal control problem with a quadratic cost function for a system, whose state is described by a linear confluent equation in Hilbert spaces are obtained. We apply these results for investigating an optimal control problem for the Dzektser equation of the evolution of the free surface of a filtering fluid.     

Study of ceramic pebble beds in Post Irradiation Examination of the Pebble Bed Assemblies irradiation experiment

The irradiation experiment Pebble Bed Assemblies (PBA) consists of four mock-up representations (test elements) of the EU Helium Cooled Pebble Bed (HCPB) concept. The four test elements contain a ceramic breeder pebble bed sandwiched between two beryllium pebble beds and are regarded as one of the first DEMO representative HCPB blanket irradiation tests, with respect to temperatures and power densities. The design value of the PBA were to irradiate pebble beds at a power density of 20–26 W/cc in the ceramic breeder, to a maximum temperature of 800 °C.Two test elements contain lithium orthosilicate pebbles (Li₄SiO₄; FZK/KIT) and were irradiated with target temperatures of 600 and 800 °C, respectively. The other test elements have lithium metatitanate (Li₂TiO₃; CEA) with different grain sizes and were both irradiated with a target temperature of 800 °C. The PBA have been irradiated for 294 Full Power Days (12 cycles) in the High Flux Reactor (HFR) in Petten to a total neutron dose of 2–3 dpa in Eurofer, and an estimated (total) lithium burnup of 2–3% in the ceramic pebbles.This work presents results of Post Irradiation Examinations (PIE) on the four HCPB test elements. Using e.g. SEM, the evolution of compressed pebble beds and pebble interactions like swelling, creep, sintering, etc., under irradiation and thermal loads are studied for the candidate pebble materials Li₂TiO₃ and Li₄SiO₄. (Chemical) interactions between ceramic pebbles and Eurofer (e.g. chrome diffusion) are observed. Looking at different sections of the pebble beds, correlations between temperatures and thermal–mechanical behaviour are clearly observed.     

Phase equilibria in the system Zr-W-C

Summary The system Zr-W-C was investigated by the methods of X-ray diffraction and microstructural analyses. Phase equilibria at 1500°C were determined for as-cast and annealed alloys. The carbide ZrC dissolves 34 mo%WC at 500°C; at l,950°C. the solubility ofWC increases to 40 mol.'yo. As-cast alloys contain the - phase, which has a cubic NaCl-type structure (a = 4.25–4.30 A), and is distributed along the 50 at.% C line at 2–10 at.% Zr. It is shown that the solubility of WC in ZrC may be even greater at temperature approaching the melting point of the alloys.     

Nonstationary absorption wave in a solid transparent dielectric

Numerical methods are used to examine the process of formation and development of a laser radiation absorption wave in a solid medium. Radiation propagation within the material is described in the geometric optics approximation.Translated from Inzhenerno-Fizicheskii Zhurnal, Vol. 42, No. 4, pp. 633–639, April, 1982.     

Boiling of fluid on a metal surface

An attempt is made to verify a hypothesis about the effect of a double electrical layer at a metal-polar-fluid boundary on the boiling process in the fluid.Translated from Inzhenerno-Fizicheskii Zhurnal, Vol. 32, No. 1, pp. 18–23, January, 1977.     

Industrial experience with petroleum coke in ferrosilicon production

The industrial use of low-ash petroleum coke instead of coke nuts in ferrosilicon production is considered. The quality and behavior of the petroleum coke in high-temperature smelting are studied. The use of petroleum coke in smelting ferrosilicon proves efficient.