Том 50, № 3 (2016)

Questions related to the substantiation of the parameters of soil-filled structures that use polymer nanocomposites are examined.

Potential flow is considered in a cylindrical coordinate system (r, z, θ), caused by a vortex filament located on the z-axis and a finite length vortex inflow-cylinder of uniform intensity distribution located on an infinite impermeable cylinder, the centerline of which coincides with the z axis, in infinite space filled with an ideal liquid. Equipotential surface (line) equations and flow surfaces (lines) are given, along with relations for determining velocity components. It is shown that the flow lines caused by a vortex inflow-cylinder lie on the flow surfaces created generated by the inflow-cylinder. Equations are given that allow lines of total flow to be projected onto planes normal to the z axis using the finite difference method. It is noted that the shape of the flow lines on the respective flow surfaces depend only on the ratio of the vortex filament intensity to inflow-cylinder flow rate.

This article presents the design, hardware, and software solutions developed and placed in service for the automated system of diagnostic monitoring (ASDM) for hydraulic engineering installations at the Bureya HPP, and assuring a reliable process for monitoring hydraulic engineering installations. Project implementation represents a timely solution of problems addressed by the hydraulic engineering installation diagnostics section.

Within the framework of the generalized theory of turbulent diffusion, we consider the mean velocities, times, length of alternating transverse up-and-down motion of suspended particles in sediment exhibiting different settling velocities and fluid particles in calm uniform wide open flows. Experimental data obtained by various authors are used to find the maximum heights and lengths of particle saltation in the thin near-bottom region, as well as the magnitude of the dynamic flow velocity, which triggers the motion of particles on the bottom. From the combined trajectory description of particle motion in sediments of different settling velocities over the entire depth of an open flow, the trajectory limit settling velocity of suspended sediments deposited in a rectilinear desilt basin may be determined and, within the framework of relaxation models, the length of silting and erosion at the bottom may be found.

A large amount of combustion products, including ash, is released into the atmosphere during combustion of solid fuels in boilers. A major task is to reduce the emissions of ash in the atmosphere as much as possible. This article describes a reconstruction of an electrostatic precipitator for medium power boilers in which the ash collectors can be modernized to increase their operating efficiency. This redesign, with initial charging of ash particles, differs from similar systems in its simplicity and cheapness. Recommendations are given for operation of electrostatic precipitators and the results of a reconstruction of an ash collector system are described. This reconstruction method can be used in solid fuel-fired boilers equipped with electrostatic precipitators.

The objective of this study is to give an understanding of how the natural frequencies and modes of the end-winding components in high-power turbogenerators can be determined. Results from an analysis of various methods are presented, and the main factors that hamper the computation of the natural frequencies with accuracy required for practical purposes are identified. Finite-element 3D modeling was performed to determine the natural frequencies of the outputs and a part of the stator bus ring. It is shown that the calculated frequencies are strongly dependent on the accuracy of modeling the boundary conditions. To improve the accuracy of numerical modeling, it is necessary to use bench and full-scale test data.

The results of combined numerical-experimental studies of the heat-transfer process in an air-cooled condenser (ACC) model are presented. The range of coordination of rational values of the average heat-transfer coefficient from air-steam mixture to tubes \( {\overline{\upalpha}}_{\mathrm{asm}} \) the average velocity of air-steam mixture entering the ACC for different temperatures of cooling air, and typical ranges of condensate depression temperatures is scientifically substantiated. A method and an algorithm for determining rational values of \( {\overline{\upalpha}}_{\mathrm{asm}} \) are outlined.

Remote means for fault location determination are intended for finding the most likely fault point and reducing the bypass zone of the line. Methods of improving the accuracy of the calculation of the distance to the fault location (and reducing the inspection zone of the OHL) owing to the use of special digital processing of fault regime oscillogram signals are examined.

The operation of modern microprocessor insulation analyzers operating at the utility frequency and implementing the two measurements method (computational method) which are widely used to assess the condition of insulation in electric equipment is analyzed. The expressions and computational results are presented for the errors appearing in tanä due to the voltage setting difference between the first and second measurements and the action of the utility-frequency interference currents on the source of the testing voltage. It is shown that the two measurements method gives acceptable errors if the voltage difference between the first and second measurements does not exceed 0.2 – 0.5%. It is noted that the level of the additional errors of the insulation analyzers using the two measurements method is comparable to the error of simple analyzers of the type Tangens-2000 operating on a non-utility frequency and having significant additional errors in the presence of utility-frequency interference currents in the distribution devices.