Clarification Of Aqueous Suspensions With A High Content Of Suspended Solids In Rapid Sand Filters

The presented work is devoted to solving the actual problem of increasing the efficiency of rapid sand filters with granular filling, which operate at a constant filtration rate when cleaning suspensions with a relatively high concentration of contaminants. The proposed mathematical model for clarifying the suspension by filtration consists of three interconnected blocks: clarified, filtration, and hydraulic. Convenient dimensionless mathematical dependencies are obtained for calculating the concentrations of contaminants and sediment from the height of the filter and suspension in the filtrate; head loss in the filter loading; the effective time of the filter (the duration of the filter cycle). The design of the experimental setup and the methodology for conducting experimental studies and mathematical processing of the results are valid. The results of experimental studies of the suspension filtering process through the granular loading are presented, and the obtained data is analyzed. Measurement of pressure losses in the filter loading is performed when a suspension is passed with a relatively high concentration of contaminants at various filtration rates. The nature of the change in the filtration rate with time and height (length) loading at various filtration rates and initial contamination concentrations is determined. Measured variable concentration of suspended matter in filtered water and retained contamination over time. As a result of the experiments, it is confirmed that an increase in the concentration of retained contaminants S leads to an increase in the parameter Δn/n. Upon reaching a certain value of the concentration of the retained sediment S (in our case S=30 g/dm3), an increase in the relative specific volume of the sediment greater than Δn/n0=0.65 is not observed. It is established that an important characteristic of the retained sediment is the ratio of the volume concentration of the sediment to the volume concentration of solid particles in this sediment γ=Csd/Сs. The values of the adhesion and detachment of particles of contaminant in the particles of the material loading =4,9; =0,009. The results of experimental studies in general confirm the correctness and reliability of the obtained analytical dependencies

CLARIFICATION OF AQUEOUS SUSPENSIONS WITH A HIGH CONTENT OF SUSPENDED SOLIDS IN RAPID SAND FILTERS

The presented work is devoted to solving the actual problem of increasing the efficiency of rapid sand filters with granular filling, which operate at a constant filtration rate when cleaning suspensions with a relatively high concentration of contaminants. The proposed mathematical model for clarifying the suspension by filtration consists of three interconnected blocks: clarified, filtration, and hydraulic. Convenient dimensionless mathematical dependencies are obtained for calculating the concentrations of contaminants and sediment from the height of the filter and suspension in the filtrate; head loss in the filter loading; the effective time of the filter (the duration of the filter cycle). The design of the experimental setup and the methodology for conducting experimental studies and mathematical processing of the results are valid. The results of experimental studies of the suspension filtering process through the granular loading are presented, and the obtained data is analyzed. Measurement of pressure losses in the filter loading is performed when a suspension is passed with a relatively high concentration of contaminants at various filtration rates. The nature of the change in the filtration rate with time and height (length) loading at various filtration rates and initial contamination concentrations is determined. Measured variable concentration of suspended matter in filtered water and retained contamination over time. As a result of the experiments, it is confirmed that an increase in the concentration of retained contaminants S leads to an increase in the parameter Δn/n. Upon reaching a certain value of the concentration of the retained sediment S (in our case S=30 g/dm3), an increase in the relative specific volume of the sediment greater than Δn/n0=0.65 is not observed. It is established that an important characteristic of the retained sediment is the ratio of the volume concentration of the sediment to the volume concentration of solid particles in this sediment γ=Csd/Сs. The values of the adhesion and detachment of particles of contaminant in the particles of the material loading =4,9; =0,009. The results of experimental studies in general confirm the correctness and reliability of the obtained analytical dependencies

Вдосконалення розрахунку збірних перфорованих трубопроводів для очисних споруд

This paper reports the results of the experimental and theoretical studies of the characteristics of perforated pipelines, which are used to collect and dispose water from capacitive treatment structures of water supply and sewerage systems. The value and nature of the change in the flow rate through the perforation holes µcol lengthwise a pipeline have been examined depending on the design characteristics of the perforated pipes and parameters of a fluid flow in the pipeline. Measurements were carried out at a specially assembled experimental bench. The experiments determined the nature of changes in the flow rate value, as well as in the piezometric line along the collector. The obtained data showed that the flow rate factor µcol varies along the length of the collecting channel. Its value depends on the ratio of the velocity of the fluid jets that enter the pipe to the average velocity in the examined cross-section (Uh/V). In this case, this ratio also changes along the path; it has a maximum value at the beginning of the pipe and a minimum value at its end. The variable flow rate factor of perforation holes, on the contrary, had a minimum at the beginning and a maximum at the end of the collector. The result of the analysis of initial equations and the findings based on experimental data has shown that calculations may assume, without a significant error, the flow rate factor value of perforation holes µcol to be constant lengthwise the collector. The impact of the transit flow rate on the value of this coefficient has also been estimated. It is shown that the increase in transit leads to a certain increase in the flow rate factor, which is averaged for the entire collector. The paper proposes empirical dependences that are convenient to use in order to calculate the flow rate factor, both variable and constant, for the case of the presence and absence of transit in the head drainage channelПредставлены результаты экспериментальных и теоретических исследований характеристик перфорированных трубопроводов, которые используются при сборе и отводе воды из емкостных очистных сооружений систем водоснабжения и водоотведения. Исследовалась величина и характер изменения коэффициента расхода отверстий перфорации μсб по длине трубопровода в зависимости от конструктивных характеристик перфорированных труб и параметров потока жидкости в трубопроводе. Измерения проводились на специально смонтированном экспериментальном стенде. В опытах определялся характер изменения величины расхода и пьезометрической линии вдоль сборника. Полученные данные показали, что коэффициент расхода μсб является переменным по длине сборного канала. Его величина зависит от соотношения скорости струек жидкости, которые втекают в трубу, к средней скорости потока в рассматриваемом сечении (Uо/V). При этом данное соотношение также изменяется по длине сборника, имело максимальное значение в начале трубы и минимальное в ее конце. Переменный по величине коэффициент расхода отверстий перфорации наоборот, имел минимум в начале и максимум в конце сборника. В результате анализа исходных уравнений и результатов экспериментальных данных показано, что в расчетах без существенной погрешности можно принимать значения коэффициента расхода отверстий перфорации μсб постоянным по длине сборника. Также оценено влияние транзитного расхода на величину этого коэффициента. Показано, что увеличение транзита приводит к некоторому увеличению среднего для всего сборника коэффициента расхода. Предложены удобные для использования эмпирические зависимости для расчета переменного и постоянного по величине коэффициента расхода для случая присутствия или отсутствия транзита в напорном водоотводящем каналеПредставлені результати експериментальних і теоретичних досліджень характеристик перфорованих трубопроводів, які застосовуються при зборі і відводі води з ємнісних очисних споруд систем водопостачання та водовідведення. Досліджувалась величина і характер зміни коефіцієнта витрати отворів перфорації μзб за довжиною трубопроводу в залежності від конструктивних характеристик перфорованих труб і параметрів потоку рідини в трубопроводі. Вимірювання проводились на спеціально змонтованому експериментальному стенді. В дослідах визначався характер зміни величини витрати і п’єзометричної лінії вздовж збірника. Отримані дані показали, що коефіцієнт витрати µзб є змінним за довжиною збірного каналу. Його величина залежить від співвідношення швидкості струминок рідини, які втікають в трубу, до середньої швидкості потоку в перерізі, що розглядається (Uо/V). При цьому дане співвідношення також змінюється вздовж шляху, воно має максимальне значення на початку труби і мінімальне в її кінці. Змінний за величиною коефіцієнт витрати отворів перфорації навпаки, мав мінімум на початку і максимум в кінці збірника. В результаті аналізу вихідних рівнянь і результатів експериментальних даних показано, що в розрахунках без суттєвої похибки можна приймати значення коефіцієнта витрати отворів перфорації μзб постійним за довжиною збірника. Також оцінено вплив транзитної витрати на величину цього коефіцієнта. Показано, що збільшення транзиту призводить до певного збільшення середнього для всього збірника коефіцієнта витрати. Запропоновані зручні для використання емпіричні залежності для розрахунку змінного і постійного за величиною коефіцієнта витрати для випадку наявності і відсутності транзиту в напірному водовідвідному канал

Circular stripe domains and cone state vortices in disk-shaped exchange coupled magnetic heterostructures

Vertically stacked exchange coupled magnetic heterostructures of cylindrical geometry can host complex noncolinear magnetization patterns. By tuning the interlayer exchange coupling between a layer accommodating magnetic vortex state and an out-of-plane magnetized layer, one can efficiently realize new topological chiral textures such as cone state vortices and circular stripe domains. We study how the number of circular stripes can be controlled by both the interlayer exchange coupling and the sample geometrical parameters. By varying geometrical parameters, a continuous phase transition between the homogeneous state, cone state vortex, circular stripe domains, and the imprinted vortex takes place, which is analysed by full scale micromagnetic simulations. The analytical description provides an intuitive pictures of the magnetization textures in each of these phases. The possibility to realize switching between different states allows for engineering magnetic textures with possible applications in spintronic devices

Circular stripe domains and cone state vortices in disk-shaped exchange coupled magnetic heterostructures

Vertically stacked exchange coupled magnetic heterostructures of cylindrical geometry can host complex noncolinear magnetization patterns. By tuning the interlayer exchange coupling between a layer accommodating magnetic vortex state and an out-of-plane magnetized layer, one can efficiently realize new topological chiral textures such as cone state vortices and circular stripe domains. We study how the number of circular stripes can be controlled by both the interlayer exchange coupling and the sample geometrical parameters. By varying geometrical parameters, a continuous phase transition between the homogeneous state, cone state vortex, circular stripe domains, and the imprinted vortex takes place, which is analysed by full scale micromagnetic simulations. The analytical description provides an intuitive pictures of the magnetization textures in each of these phases. The possibility to realize switching between different states allows for engineering magnetic textures with possible applications in spintronic devices

Rashba Torque Driven Domain Wall Motion in Magnetic Helices

Manipulation of the domain wall propagation in magnetic wires is a key practical task for a number of devices including racetrack memory and magnetic logic. Recently, curvilinear effects emerged as an efficient mean to impact substantially the statics and dynamics of magnetic textures. Here, we demonstrate that the curvilinear form of the exchange interaction of a magnetic helix results in an effective anisotropy term and Dzyaloshinskii--Moriya interaction with a complete set of Lifshitz invariants for a one-dimensional system. In contrast to their planar counterparts, the geometrically induced modifications of the static magnetic texture of the domain walls in magnetic helices offer unconventional means to control the wall dynamics relying on spin-orbit Rashba torque. The chiral symmetry breaking due to the Dzyaloshinskii-Moriya interaction leads to the opposite directions of the domain wall motion in left- or right-handed helices. Furthermore, for the magnetic helices, the emergent effective anisotropy term and Dzyaloshinskii-Moriya interaction can be attributed to the clear geometrical parameters like curvature and torsion offering intuitive understanding of the complex curvilinear effects in magnetism

Curvature induced magnonic crystal in nanowires

A new type of magnonic crystals, curvature induced ones, is realized in ferromagnetic nanowires with periodically deformed shape. A magnon band structure of such crystal is fully determined by its curvature: the developed theory is well confirmed by simulations. An application to nanoscale spintronic devises with the geometrically tunable parameters is proposed, namely, to filter elements.Comment: 21 pages, 6 figures, for submission to SciPos