Improvement of Strength and Strain Characteristics of Lightweight Fiber Concrete by Electromagnetic Activation in a Vortex Layer Apparatus

The relevant problem of choosing effective materials for enclosing structures is compliance with the requirements of increased thermal resistance, reduced mass of buildings and structures, and reduced material consumption, labor intensity, and construction costs. These requirements are satisfied by structures made of lightweight fiber-reinforced concrete, which are the subject of attention of many scientists and engineers. One of the most rational requirements for industrial use is the activation of untreated components of the concrete mixture. This article is devoted to studying the influence of the activation of fiber-reinforced concrete elements in the vortex layer apparatus on concrete strength and structural characteristics. The effect of the raw component processing time of the concrete mixture on the strength and deformation characteristics of the lightweight fiber-reinforced concrete was studied. The optimal processing time for the cement–sand mortar in the VLA-75-85s was determined. It was shown that the activation of the vortex layer in the apparatus leads to an increase in strength from 27% to 61% and an improvement in the deformation characteristics of lightweight fiber-reinforced concrete by up to 12%. Furthermore, it was found that the use of activation in VLA leads to an increase in the coefficient of constructive quality for all experimentally determined strength characteristics of lightweight fiber-reinforced concrete by up to 27%.

Complex singularity analysis for vortex layer flows

We study the evolution of a 2D vortex layer at high Reynolds number. Vortex layer flows are characterized by intense vorticity concentrated around a curve. In addition to their intrinsic interest, vortex layers are relevant configurations because they are regularizations of vortex sheets. In this paper, we consider vortex layers whose thickness is proportional to the square-root of the viscosity. We investigate the typical roll-up process, showing that crucial phases in the initial flow evolution are the formation of stagnation points and recirculation regions. Stretching and folding characterizes the following stage of the dynamics, and we relate these events to the growth of the palinstrophy. The formation of an inner vorticity core, with vorticity intensity growing to infinity for larger Reynolds number, is the final phase of the dynamics. We display the inner core's self-similar structure, with the scale factor depending on the Reynolds number. We reveal the presence of complex singularities in the solutions of Navier–Stokes equations; these singularities approach the real axis with increasing Reynolds number. The comparison between these singularities and the Birkhoff–Rott singularity seems to suggest that vortex layers, in the limit $Re\rightarrow \infty$ , behave differently from vortex sheets.

The vortex layer apparatus as a source of low-grade heat in the process of pretreatment of the substrate before anaerobic digestion

The limiting stage of anaerobic digestion (AD) of organic waste is the hydrolysis of particulate organic matter. One of the most promising and energy-efficient methods of waste pretreatment before AD is its processing in a vortex layer apparatus (VLA). The work was aimed at experimentally determining the energy characteristics of VLA. The description of the experimental plant and its energy balance were given. The ranges of electricity consumption and heat generation were shown. According to experimental data, the coefficient of conversion of electricity into heat was in the range of 0.367-0.515 at a cooling water temperature of 10.6-11.7 oC. Based on the experimental data obtained, it can be argued that VLA is a stable source of low-grade heat that can be utilized using heat pumps.

Vortex Layer on the β-Plane in the Miles – Ribner Formulation. Pole on the Real Axis

Purpose. The problem of a non-zonal vortex layer on the β-plane in the Miles – Ribner formulation is considered. It is known that in the absence of the β-effect, the vortex layer has no neutral eigenmodes, and the available two ones (varicose and sinusoidal) are unstable. Initially, generalization of the problem to the β-plane concerned only the zonal case. The problem for a non-zonal vortex layer is examined for the first time in the paper. It is known that in the WKB approximation for the linear wave disturbances (regardless of whether a zonal or non-zonal background flow is considered), there is an adiabatic invariant in the form of the law of the enstrophy (vorticity) conservation. For the zonal vortex layer, the enstrophy conservation law also holds, and no vorticity exchange occurs between the waves and the flow in the zonal case. The non-zonal vortex layer has qualitatively different features; particularly, it does not retain enstrophy. Thus, as a result, there appears a new class of solutions which can be interpreted as pure radiation of the Rossby waves by a non-zonal flow. Generalizing the vortex layer problem on the β-plane to the non-zonal case constitutes the basic aim of the present study. Methods and Results. A new class of linear stationary wave solutions, namely the Rossby waves, is found. It is shown a non-zonal flow can be directed in one way, whereas the stationary wave disturbances can move in the opposite (contrary) direction. The coexistence of such solutions for the shear non-zonal flow and stationary wave disturbances takes place due to the influence of the external force and mathematically comes from a non-self-adjoining character of the linear operator for a non-zonal background flow. Conclusions. There exists a new class of solutions that can be interpreted as pure radiation of the Rossby waves by a non-zonal flow. There is no such solution for a zonal flow. It is just non-zoning that gives the effect of pure radiation and corresponds to the classical definition of radiation. This approach makes it possible to eliminate inconsistency in terminology, when instabilities are mistakenly called radiation, and radiation – pure radiation.

Results of researching the process of treatment of cattle manure in a vortex layer apparatus

The results of studies of the of cattle manure treatment in the vortex layer apparatus are presented. It has been found that these devices can treat manure having a moisture content of more than 93% and a particle content of maximum 7 mm in size. With an increase in the moisture content of manure from 93% to 96%, the energy intensity of the dispersion process decreases from 0.7 kWh / t to 0.53 kWh / t, the productivity increases to 22 t / h, and the weight of ferromagnetic elements loaded into the apparatus should be in the range of 285 g to 400 g.

APPLICATION OF THE VORTEX LAYER APPARATUS FOR MECHANICAL GRINDING OF SUBSTANCES IN A WATER FLOW

With the expansion of the crushing equipment for various substances, the issues of the energy intensity of the process, the duration of grinding, the profitability of the devices with the required quality of grinding are acute. (Research purpose) The research purpose is in justifying the technical solutions for the use of vortex layer apparatuses as activators of the processes of crushing and converting organic agricultural waste during their pre-treatment for further utilization in biogas plants. (Materials and methods) Authors evaluated the efficiency of pretreatment of animal waste in the developed 1.3 kilowatt vortex layer apparatus; steel needles were used as ferromagnetic elements with a diameter/length ratio of 1/10. Logical analysis of existing experimental data on the processes occurring in the vortex layer apparatuses with the use of control equipment and statistical data processing were used as research methods. (Results and discussion) The article presents the most significant factors affecting the biogas yield in the vortex layer apparatuses. Cavitation and the mechanical action of ferromagnetic elements have the greatest influence on the processes of waste crushing. The use of vortex layer devices stimulates the microbiological activity of metagens of biogas plant, eliminates possible clogging of communications with the available inclusion of vortex layer devices in the existing technological scheme. (Conclusions) The article proposes the design of the vortex layer apparatus with an installed capacity of 1.3 kilowatts and a capacity of two liters per minute. It is advisable to use vortex layer devices for fine grinding of plant products and waste, preparation of stable colloidal solutions and intensification of chemical and microbiological processes with high productivity and low specific energy consumption.

Determination of the Probability of Penetration of Manure Particles Through the Layers of Ferromagnetic Elements in the Vortex Layer Devices

Theoretical dependences are presented for determining the probability of penetration of manure particles through the layers of rotating ferromagnetic elements in the vortex layer device taking into account their number and geometrical dimensions, and parameters of the working area.

Processing of Compounded Oil Feedstock with Pre-Activation of Initial Raw Material Flows

In laboratory conditions, a variant of a systematic approach to the realization of experiments, involving a combination of activation and compounding of oil feedstock before primary processing, was implemented. The influence of pre-activation of raw material flows (one or both of them) in the disintegrator DA-1 and in the vortex layer apparatus on the fractional composition of compounded feedstock with the same ratio of mixed oils was studied. The possibility of priority production of the most popular fractions from various mixtures of raw materials flows has been established. Regularities of changes in the fractional composition were analyzed using a complex characteristic of oil feedstock – fluidity.