Vol 64, No 5 (2019)

Computer simulation of mixing in a system of mobile coaxial cylinders has been performed. Detailed spatial and temporal patterns of the processes occurring are obtained, and the main structures in the flow field are determined. A method for profiling the rotor is proposed based on analysis of singularities of the flow-velocity vector field. Similarity numbers are introduced, which allow one to pass from laboratory bench systems to real commercial apparatuses.

Methods for modifying the surface of Pd–23%Ag alloy films and synthesizing nanostar- and nanopore-type palladium coatings, which enhance the hydrogen transport rate, were developed. The gas-transport parameters of membranes with their surfaces activated this way were examined. Pd–Ag films with surfaces modified by star-shaped palladium nanocrystallites demonstrate hydrogen flow densities as high as 0.75 mmol/(s m²) under low temperatures (<100°С) and pressures (<0.6 MPa) if the palladium membranes are sufficiently thin (<10 μm). The flow density provided by nanopore-type coatings is 1.7 times lower.

The van-der-Waals interaction between carbon nanotubes leads to the formation of agglomerates of bundles and strands. In such a self-assemblage, identical nanotubes are assembled into arrays with a high degree of ordering forming a crystalline structure. However, the van-der-Waals forces also result in a strain of the cross-section normal to their axes instead of only in the mutual attraction of nanotubes. This work presents an analysis of the nanotube strain and crystal-lattice parameters depending on the nanotube sizes and crystal symmetry.

The structural aspects of determining the degree of reinforcement (increase in elasticity modulus) of carbon polymer–nanotube composites with ultralow concentrations of nanofiller are considered. It is shown that the specified parameter is controlled by two factors, the structure of the nanocomposite and the type of reinforcing component. The introduction of a nanofiller in the polymer matrix modifies its structure due to the formation of interfacial regions. Hence, the efficiency of nanofiller as the reinforcing element is determined by its ability to generate interfacial regions.

The effect of the replacement of the exact yield condition by that averaged over the distribution of residual stresses in a thin hollow disk subjected to external pressure and subsequent unloading is investigated. The formulation of the boundary-value problem is specially simplified so that it is possible to obtain a mathematically exact semi-analytical solution, with the help of which it is easy to investigate the effect of averaging the yield condition on the stressed state including the distribution of residual stresses. The accepted exact yield condition is averaged using several generally accepted approaches. The comparative analysis of the distribution of residual stresses shows a significant deviation of the distribution resulting from solutions for the averaged yield conditions from the exact distribution of residual stresses.

The results of calculation and theoretical investigation for the creation of a powerful (~600 MW) pulsed MHD generator on the combustion products from solid (powder) plasma-forming fuel “Start-2” of a new generation are presented. The scheme, methods, results of calculations, and optimization of characteristics of the pulsed MHD generator with the self-excited resistive “iron-free” magnetic system are described. The local, integral, and specific energy and mass-dimensional characteristics are determined.