Research and results of mathematical modeling of block ion-exchange water treatment plants operating modes and regeneration

The problem of water treatment at thermal power plants using ion-exchange technologies is a multi-parameter task. Mathematical modeling is essential for research and optimization of ion exchange technology. The analysis of hydrodynamic processes during the operation of ion-exchange filters was carried out according to the developed mathematical model. Also, a physicochemical analysis of the composition of the water treatment plant solutions under real conditions was carried out. It is shown that in the cationite and anionite filters, the flow movement occurs mainly in a mixed hydrodynamic mode. This mode of regeneration and the filter design do not allow achieving the minimum consumption of the reagent for regeneration, the minimum volume of wastewater and the maximum output of demineralized water. The mixed mode of the anion exchange filter operation allows division of the outgoing solution flow into fractions, which can be successfully used in the TPP water cycle.

Hydrodynamics of Absorption Bubbling Apparatus

The article proposes an improved design of the energy-saving, compact absorption bubbling apparatus, which cleans the particles and gas mixtures in the exhaust gases of industrial enterprises, has a high absorption efficiency. As a result of theoretical research, an equation has been proposed that calculates the value of the height of the gas cushion “h”, which provides equal distribution of purified gas to the mixing sections of the apparatus and operation in a stable hydrodynamic mode. As a result, depending on this value, it is possible to calculate the gas velocities and the gas consumption supplied to the apparatus.

Experimental research of mass transfer in a stabilized foam layer

The object of research: mass transfer processes on a combined contact element in a column apparatus. Investigated problem: determination of the regularities of process parameters in the processing of gas-liquid systems in a foam layer, as well as to interpret the obtained experimental data. The problem of processing industrial gas flows is solved by conducting the process in an intensive mode. The main scientific results: as a result of the study, the regularities of ammonia absorption were revealed depending on the main parameters of the experiment: gas velocity in the column cross-section, ammonia concentration, free cross-section of the combined contact element, and liquid loads. The process of mass transfer in the gas phase is significantly influenced by hydrodynamic parameters – the gas velocity in the apparatus and the specific load on the liquid, which indirectly affect the height of the liquid layer on the plate and the gas content of the layer. The area of practical use of the research results: sorption processes for processing gases and liquids in technological processes, absorption of harmful substances in the treatment of gas emissions. Innovative technological product: new block poppet-nozzle contact device that operates in a stabilized hydrodynamic mode; new ball-shaped weighted nozzle for three-phase foam layer. Scope of application the innovative technological product: technological processes in the treatment of gas emissions or technological gases.

Impact of a Centrebody On the Unsteady Flow Dynamics of a Swirl Nozzle: Intermittency of PVC Oscillations

The precessing vortex core (PVC) is a self-excited flow oscillation state occurring in swirl nozzles. This is caused by the presence of a marginally unstable hydrodynamic mode that induces precession of the vortex breakdown bubble (VBB) around the flow axis. We examine the impact of a centrebody on PVC dynamics in a non-reacting flow in a swirl nozzle combustor. Time resolved high speed stereoscopic PIV measurements are performed for two swirl numbers, S=0.67 and 1.17 and three centrebody diameters, 9.5mm, 4.73mm and 0 (i.e. no centrebody). The bulk flow velocity at the nozzle exit is kept constant as Ub=8m/s for all cases (Re~20,000). The data is analyzed using a new modal decomposition technique that combines the wavelet transform and proper orthogonal decomposition (WPOD). This gives insight into globally intermittent flow dynamics. A coherent PVC is present in the flow when there is no centrebody. Introducing a centrebody makes the PVC oscillations intermittent. The WPOD results show two qualitatively different intermittent behaviours at S=0.67 and 1.17. For S=0.67, the axial position of the VBB suggests that turbulence destabilizes the PVC mode by causing intermittent separation of the VBB and centrebody wake, resulting in PVC oscillations. For S=1.17, the VBB engulfs the centrebody and stabilizes the PVC mode. Therefore, in this case, PVC oscillations appear to be the flow response to broadband stochastic forcing of the time averaged flow by turbulence.

A method to predict the flow-induced noise of an open cavity of a complex geometry

Shear flow past a cavity involves a complex fluid dynamic process. Of vital importance is the occurrence of self-sustained oscillations that give rise to tones and the amplitudes of which may be further amplified if the hydrodynamic mode is coupled with the cavity mode. Extensive efforts have been made to investigate the mechanisms of such a simple yet compelling system as well as to predict the noise generated, while most of them are focused on geometry of rectangular shape. For an irregular shaped cavity, numerical methods are usually used which are computationally expensive. A method is developed to predict the tones generated by the shear flow past an open cavity of a complex geometry. In view of the feedback process involved within the system, a describing-function method decomposing the system into a non-linear part and a linear part is used. The linear description function is established by the patch mobility method where the transfer function between patches is extracted from finite element results, while the nonlinear description function is established based on the vortex sound theory. The proposed method showed a superb computation efficiency over CFD method and its accuracy was justified by comparing with the results of public literature.

Studying the Effect of Fuel Elements Structural Materials Corrosion on their Operating Life

The paper deals with experimental data regarding the effect of internal and external factors on the corrosion decay of Zr1Nb alloy fuel elements. Based on the analysis results, losses of zirconium that transfers to oxide or coolant as per the fuel element wall weight and thickness as well as economic losses from their corrosion decay have been theoretically calculated. To avoid a state-level emergency occurrence, an increase in the fuel element wall thickness up to 660 μm is proposed, which can increase the operating life under the conditions of trouble-free coolant mass transfer hydrodynamic mode.

Critical behaviour of hydrodynamic series

We investigate the time-dependent perturbations of strongly coupled $$ \mathcal{N} $$ N = 4 SYM theory at finite temperature and finite chemical potential with a second order phase transition. This theory is modelled by a top-down Einstein-Maxwell-dilaton description which is a consistent truncation of the dimensional reduction of type IIB string theory on AdS5×S5. We focus on spin-1 and spin-2 sectors of perturbations and compute the linearized hydrodynamic transport coefficients up to the third order in gradient expansion. We also determine the radius of convergence of the hydrodynamic mode in spin-1 sector and the lowest non-hydrodynamic modes in spin-2 sector. Analytically, we find that all the hydrodynamic quantities have the same critical exponent near the critical point θ = $$ \frac{1}{2} $$ 1 2 . Moreover, we propose a relation between symmetry enhancement of the underlying theory and vanishing of the only third order hydrodynamic transport coefficient θ1, which appears in the shear dispersion relation of a conformal theory on a flat background.

On the universality of AdS2 diffusion bounds and the breakdown of linearized hydrodynamics

The chase of universal bounds on diffusivities in strongly coupled systems and holographic models has a long track record. The identification of a universal velocity scale, independent of the presence of well-defined quasiparticle excitations, is one of the major challenges of this program. A recent analysis, valid for emergent IR fixed points exhibiting local quantum criticality, and dual to IR AdS2 geometries, suggests to identify such a velocity using the time and length scales at which hydrodynamics breaks down — the equilibration velocity. The latter relates to the radius of convergence of the hydrodynamic expansion and it is extracted from a collision between a hydrodynamic diffusive mode and a non-hydrodynamic mode associated to the IR AdS2 region. In this short note, we confirm this picture for holographic systems displaying the spontaneous breaking of translational invariance. Moreover, we find that, at zero temperature, the lower bound set by quantum chaos and the upper one defined by causality and hydrodynamics exactly coincide, determining uniquely the diffusion constant. Finally, we comment on the meaning and universality of this newly proposed prescription.

THE CYBER-PHYSICAL SYSTEM FOR COULOSTATIC EXPERIMENT. THE CORROSION MONITORING UNIT

Cyber-physical approach shows new perspectives in solution of actual problem of computerized corrosion monitoring. It was analyzed for special case of the coulostatic tech-nique used for determination of corrosion rate. Basic problems concerning polarization control, computing of relaxation equations, simulation of hydrodynamic mode were revealed.

Predicting groundwater rise in historical centres of Eastern Siberian cities

The purpose of the research work is to develop a procedure for on-line prediction of the groundwater hydrodynamic mode change caused by the barrage effect of deep foundation structure construction. The main method used is the development of an analytical model as a result of variant solutions of the Laplace equation. The solutions have been elaborated in the course of studies conducted in historical centers of Irkutsk and other cities of Eastern Siberia. As a result, diagrams predicting the formation depth of groundwater level have been created, and the territories have been assessed according to their flooding conditions. An analytical model has been developed for backwater prediction. The model is rather simple, universal and can be applied for predictive calculations on the territories of historical cities located in similar geological and hydrogeological conditions. The available material analyzed, it is concluded that preliminary vertical planning of the territory, correct approach to foundation type selection as well as seasonal rise of underground water play a significant role in the formation of a new headwater elevation.