Dynamic Viscosity Coefficient Research Articles

Dynamic viscosity, interfacial tension and diffusion coefficient of n-hexane, cyclohexane, 2-methylpentane with dissolved CO2

In this work, n-hexane, cyclohexane and 2-methylpentane were selected to represent linear-alkane, cycloalkane and branched-alkane, respectively. Based on the dynamic light method (DLS), the viscosity, interfacial tension and diffusion coefficient of n-hexane/CO2, cyclohexane/CO2 and 2-methylpentane/CO2 systems under saturation condition were measured in order to explore the change trend of thermophysical properties of the systems with the same carbon atom number but different molecular structures. The experiments were conducted at the temperatures of 303, 343 and 383 K and at pressures up to 5.64 MPa. The expanded uncertainties（k = 2）of dynamic viscosity, interfacial tension and diffusion coefficient were 3 %, 3 % and 4.4 % respectively. The experimental results show that n-hexane and 2-methylpentane with similar molecular structure have more similar value of the properties. The effects of different alkane structures on system viscosity, interfacial tension, and diffusion coefficient were explained at the molecular level through radial distribution function, interface thickness, and CO2 coordination number. At 303.15 K and 4 MPa, the peak radial distribution function of CO2/cyclohexane is 1.845, which is greater than that of CO2/n-hexane and CO2/2-methylpentane molecules. It has been proven that the arrangement of CO2/cyclohexane is more orderly, resulting in higher viscosity and lower diffusion coefficient of the system. The interface thickness of CO2/cyclohexane is 6.13 nm which is smaller than CO2/n-hexane (7.53 nm) and CO2/2-methylpentane (6.3 nm). The smaller the interface thickness, the more compact the structure, the stronger the intermolecular forces, and the greater the interfacial tension. At 303.15 K and 2 MPa, the number of CO2 coordination sites within 1 nm around liquid phase alkanes is 3.96, which is smaller than 4.78 for cyclohexane and 6.62 for 2-methylpentane. Prove that the coordination number is directly proportional to the diffusion coefficient and inversely proportional to viscosity and interfacial tension.

New mathematical models for the load factor of slip pairs of the ship propulsion complex for non-Newtonian lubricants

The method of boundary variation was applied to the solution of the boundary value problem with respect to the Reynolds differential equation for the lubricating layer in the sliding bearings of ship power plants and auxiliary ship equipment, which made it possible to obtain analytical representations for the hydrodynamic pressure, shear stresses, as well as the integral characteristics of the lubricating layer. This made it possible to build new, easy-to-use mathematical models for the load factor (carrying force factor) of the sliding pairs of the ship propulsion complex, considering the non-Newtonian properties of lubricants, i.e. in the case of the dependence of dynamic viscosity on pressure and temperature. Mathematical models take into account geometric parameters of bearings, operational parameters: relative radial clearance and relative eccentricity, angular velocity; as well as viscosity characteristics of lubricants, in particular, dynamic viscosity and piezo coefficient of viscosity of lubricants. A criterion for the applicability of lubricants for given operating characteristics and bearing parameters has been developed, which uses the viscosity characteristics of lubricants. The research results are illustrated in the form of tables and graphs.

Investigation of the Newtonian fluids flow in circular horizontal tubes at low inlet pressures

The issues of increasing hydrodynamic efficiency, improving the operational and technical characteristics of various apparatus and devices used in the fi eld of heat and mass transfer, as well as ensuring the required regime and flowow conditions of liquids of different viscosities do not lose their relevance. To solve these issues, in addition to studying the nature of the flowow of various liquids in round horizontal tubes (capillaries), it is necessary to determine the conditions when the flowow of liquid in capillaries and round tubes of small diameter is laminar and can be described by the Poiseuille equation. Experimental data on determining water flow ow through horizontal round tubes of various diameters are presented. Determining the patterns and features of such flow ows is mostly aimed at increasing hydrodynamic efficiency, improving the operational and technical characteristics of various apparatus and devices, as well as ensuring the required flow ow regime and conditions. Experimental data on determining the flow ow rate of water through horizontal tubes of circular cross-section with different diameters are presented in the article. The dependence of the volumetric flow ow rate on the pressure drop has been determined; it has been shown that the main parameters that determine the nature of the flow ow of liquids in horizontal tubes are the tube radius and the dynamic viscosity of the liquid. The flow ow of distilled water in tubes with diameters of 0.95, 1.6 and 2.0 mm at an overpressure of 0.266 kPa to 4 kPa is considered. It is shown that the dependence of the volumetric flow ow rate on the excess pressure remains linear at 0.95 mm in the entire considered pressure range. An increase in the tube radius increases the likelihood of velocity flow uctuations and the appearance of a radial velocity component, i.e. the occurrence of elements of a turbulent structure. In this regard, with tube diameters of 1.6 and 2.0 mm, a deviation of the water flow ow regime from the laminar character was established at pressures of more than 1.3 kPa and 1 kPa, respectively. The dependence of the volumetric flow ow rate on pressure for a 40 % aqueous solution of CaCl2, transformer, transmission and engine oils with dynamic viscosity coefficients from 0.002 Pa·s to 0.182 Pa·s remains linear up to pipe diameters of 5–6 mm. The experimental results are shown in the form of a nomogram of the dependence of the coefficient K* on the tube radius at different values of the viscosity coefficient. The results of studies of liquids of various viscosities are presented in the form of a nomogram of the dependence of the ratio of the radius of the tube to the fourth power to the viscosity of the liquid on the radius of the tube. The analysis of which makes it possible to predict the nature of the flow ow of the investigated liquid at the given values of the tube radius and the dynamic viscosity coefficient. Heat exchange devices for the design of which the presented results can be used include a variety of radiators that include tubes through which coolant circulates.

МОЛЕКУЛАЛАРДЫҢ АКТИВАЦИЯЛЫҚ ЭНЕРГИЯСЫН СИПАТТАЙТЫН ФИЗИКАЛЫҚ ПАРАМЕТРЛЕРГЕ ТӘУЕЛДІЛІГІН ЗЕРТТЕУ ӘДІСТЕРІ

The article describes the principles of operation of devices that practically determine the activation energies of molecules of liquids, discusses their advantages and disadvantages from each other. Methods for calculating the activation energy by measuring parameters that determine the dynamic and kinematic viscosity coefficients of liquids are shown. The physical meanings of formulas describing the empirical dependence of the relaxation time of molecules using the activation energies, the dynamic viscosity coefficient on the temperature with the activation energy are discussed in detail and analyzed that they have a great influence on a full understanding of the mechanisms of physical processes and phenomena. A way to calculate the kinematic viscosity coefficients using the density and dynamic viscosity coefficients of liquids is shown. Using practical measurements and formulas that express the laws of physics, it was theoretically possible to summarize what parameters the law describing activation energy depends on. Particular attention is paid to the place that the formulas obtained as a result of theoretical calculations occupy in the study of physical phenomena.

Modelling the centrifugal mixing process of minced meat to optimise the production of chopped meat semi-finished products

One of the most important problems in ensuring the quality of mincemeat preparation in the production of sausages is the effective structuring of components and mixing of their ingredients. To solve this problem, researchers added a multifunctional admixture based on whey protein in the process of centrifugal mixing of the components, which determined the composition of the factor space of the investigated process. Based on the results of the research, the effective content of whey protein, sodium alginate, and soy fiber in the developed recipe was proven, which showed high characteristics in terms of fat-retaining and moisture-retaining ability, digestibility, pH level – activity, and other parameters. The developed formulation made it possible to improve the general indicator of the balance of amino acids in the product and increase the functional-technological and quality parameters of the developed products. The physical and mechanical characteristics of the obtained meat product were evaluated based on the results of physical and mathematical modelling. Modelling was carried out using Federman-on-Buckingham's second similarity theory and the "dimension theory" method, which allows the processing of the obtained experimental data in the form of a criterion equation, which was compiled using Froude, Euler, and Sherwood criteria. The purpose of this study was to obtain dependencies between such process factors as product density, the coefficient of dynamic viscosity of the technological medium, the ultimate shear stress, the change in the concentration of the main impurities of lactic acid in the raw material, the value of the diffusion coefficient and the coefficient of mass transfer in the loading mass, the weight of one load of products, the angular frequency of rotation of the screws of the minced meat mixer, the radius of the rotating working bodies, the characteristic size of the products after grinding. Using the complex criterion equation and the developed program, we find a recommended set of operating mode parameters for preparing minced meat under the conditions of centrifugal influence on the mixing process and the action of the specified factors.

Investigation on the Lubrication Heat Transfer Mechanism of the Multilevel Gearbox by the Lattice Boltzmann Method

In a gear transmission system in a closed space, the heat transfer between gears and fluids presents highly nonlinear characteristics due to the complex physical processes involved in heat exchange and fluid motion, and constructing and solving the thermodynamic model of the gearbox becomes a task that involves considerable difficulty. This paper takes a conical–cylindrical two-stage gearbox as the research object, proposes a fluid–solid coupled dynamics model based on the lattice Boltzmann (LBM) combined with the large eddy simulation (LES) method, and the adopted lattice model is the D3Q27 velocity model, which is used to numerically simulate the distribution of the flow field inside the gearbox and undertake in-depth research on the fluid motion law of the complex gear transmission system in the enclosed space. The model is solved to reveal the laws determining the gear speed and the effects of the lubricant’s dynamic viscosity and thermal conductivity coefficient on the gear heat dissipation efficiency. By adopting the lattice Boltzmann method, we can simulate the fluid flow and heat transfer inside the gearbox more efficiently, which provides a new way to closely understand the thermodynamic behavior of closed complex gear transmission systems. The application of this method is expected to provide strong support for thermal performance optimization and the design of gear transmission systems.

Temperature effect analysis of paste backfill rheological properties based on inter-particle potential and water evolution

This study focuses on investigating the rheological properties and micro-mechanisms of paste filling materials under varying temperatures, which is crucial for addressing the issue of transporting paste materials through pipelines at different temperatures. The rheological properties of Pure Tailing sand Paste Backfill (TPB) with a mass concentration set at 66% and Cement Paste Backfill (CPB) with a 1:4 ratio of the cementing agent were analyzed at different temperatures were compared and analyzed at different temperatures using rheometer, Zeta potential, and low-field nuclear magnetic resonance measurement technology. The study aims to identify the macroscopic trends in the dynamic yield stress and viscosity coefficient of paste slurry under temperature influence, and to determine the microscopic mechanisms of the competition between water activity and electrostatic interaction between particles. The study not only examines the characteristics of paste slurry at macro and micro levels but also provides a model of rheological parameters and temperature for the optimization of paste filling technology. Studies have shown that temperature has the opposite effect on dynamic yield stress and consistency factor, and both should be considered in practical applications.

Study of the Rheological Properties and Flow Process of High-Viscosity Oil Using Depressant Additives

This article analyzes the dependence of the choice of the method of transportation of high-viscosity oil on the rheological characteristics of the oil in question. An analysis of existing rheological models of high-viscosity oil was carried out, and it was found that a number of models have certain features (model coefficients, their purpose, quantity) that affect the choice of a rheological model of oil. The dependences for determining the coefficient of dynamic viscosity when pumping high-viscosity oil with the addition of pour-point depressants were studied, and the dependence of the hydraulic resistance coefficient when depressants are added to the oil was obtained. A method for choosing a rational oil heating temperature and diluent concentration to achieve the maximum pipeline performance is substantiated.

Effect of StaticMagneticand Pulsated Electromagnetic Fields On the Dynamic and Kinematic Viscosity of Metal Cutting Fluids

In this paper, authors investigated the difference between the influenceof staticmagnetic field and pulsating electromagnetic field on metal cutting fluids. Two essential physical parameters of the cutting fluids, dynamic and kinematic viscosity coefficients were analyzedduring the experiment in the same laboratory condition.The results obtained from the experimental researchshow thatthe influence of thestatic magnetic field onsample metal cutting fluids is greaterthanthe influence ofthe pulsating electromagnetic field.Such as, after magnetizing cutting fluids under the effect of three various static magnetic field strengths, the kinematic and dynamic viscosity havedecreased about 17%and 6% respectively,while they declined about 7% and 4% after magnetizing the fluidsunder the effect of the same electromagnetic magnetic field strengths. Moreover, special magnetizing devices have beendesigned to magnetize different types offluids intheirflowing condition.

Rheological Analysis of 3D Printed Elements of Acrylonitrile Butadiene and Styrene Material Using Multiparameter Ideal Body Models.

The growing application of additive technologies in various industrial fields determines the undertaking of research in this direction. The need to study mechanical properties, including rheological properties, is necessitated by the use of additively manufactured models as utility models. Furthermore, the values of mechanical properties are affected by the technological parameters of 3D printing. One of the popular engineering materials used in 3D printing is acrylonitrile butadiene and styrene, commonly known by the abbreviated name ABS, which is quite hard and resistant to high temperatures. This article presents a study of the rheological properties of ABS material using multiparameter ideal body models. Two rheological phenomena of stress relaxation and creep were evaluated. The effects of two technological parameters, layer height and printing direction, on the resulting values of elastic moduli and dynamic viscosity coefficients were also evaluated. The elastic moduli and dynamic viscosity coefficients were calculated using the Maxwell-Wiechert and Kelvin-Voight models. The study showed the effect of layer height on rheological properties. Moreover, very good fit was obtained between the multiparameter rheological models and the experimental curves, which are shown by the average value of and . The presented research can be used by designers to design machine parts or car or aircraft components. Moreover, research expands knowledge of the mechanical properties of additively manufactured parts.

Experimental Study on Overall Cooling Effectiveness of Turbine Nozzle Guide Vane with Impingement-Cutback Structure

The overall cooling performance of turbine nozzle guide vane, with the impingement-cutback structure, is experimentally studied in the actual-scale cascade. The gas with the high temperature is used to achieve the actual dynamic viscosity coefficient and the density ratios. The coolant-to-gas mass flow ratio (KG) varies between 0.034 and 0.050 and the gas-to-coolant temperature ratio (KT) varies between 1.5 and 2.4. The local Overall Cooling Effectiveness (OCE) on the middle cross-section of the vane is obtained. The experimental results reveal that the lowest value of the OCE achieves a 10% relative arc length on the suction side of the vane; however, the highest value appears at 40% relative arc length on the pressure side of the vane. The averaged values of the OCE are respectively enhanced by 19.45%, 24.22%, and 35.57% at temperature ratios equal to 1.7, 1.9, and 2.3, with an increase of the KG from 0.034 to 0.050. Added to that, it was identified that an increase of KT from 1.7 to 2.3 leads to the decrease of the OCE. The comparison results show that this characteristic becomes dramatical while KG is 0.034. The higher KT leads to a greater influence of KG, which is illustrated clearly by the compared results of the OCE.

Автоматизация теплового расчета реактора для производства серосодержащего сорбента при разогреве реакционной смеси

The article highlights the problem of automation the thermal design of a reactor for the synthesis of a sulfur-containing sorbent obtained from the use of waste products of epichlorohydrin, chlorinated lignin and sodium polysulfides is considered. Automated design helps to reduce the intensity of the process, improve the quality of design decisions, significantly reduce production costs, which has a positive effect on the cost of finished products. It has been found that due to the incompatibility of the similarity criteria of chemical and mass transfer processes there is little possibility to carry out a large-scale transition in a reactor based on physical similarity. In the course of a large-scale transition from a laboratory unit to a small production unit there were used the computational methods based on engineering experience that allow increasing the reliability of the results obtained. There have been determined the initial values, which will be used in the design for a reactor with a propeller agitator to mix a working mass having a dynamic viscosity coefficient of 6.01 sP and a solid phase content of 31.8%. The agitator type was determined by calculating the physical properties of the ingredients and selecting the mixer designs. A flowchart and a formal description of the algorithm for calculating heat transfer during a reaction mixture heating are given; the program interface is written in C# displaying the results of thermal design of the working mixture heating. As a result of the calculation, there has been calculated the amount of heat and time required to heat the working mixture, coefficient of heat transfer from the working mass to the reactor wall, mass flow rate of water and its costs, velocity of water in the thermal jacket, mode of water flow in the jacket and other similarity criteria.

Параметрические исследования течений в микросоплах

The work is devoted to parametric investigations of the krypton flow in a conical micronozzle when flowing into a region with low pressure. The features of the flows are studied at various values of the stagnation pressure in the pre-nozzle volume, including the occurrence of a condensed phase in the flow. Mathematical modeling was carried out on the basis of a numerical solution of the complete system of Navier-Stokes equations, supplemented by the equation for the mass fraction of the condensate. The mathematical model takes into account the change in the coefficients of dynamic viscosity and thermal conductivity depending on the gas temperature. The problem was solved by the control volume method on a block-structured regular grid of quadrangular elements using schemes of the second order of accuracy. The equations were integrated with respect to time using the Runge-Kutta method. The calculations were carried out at stagnation pressures of 5, 10, and 15 atm for single-phase and two-phase flows. The distribution fields of temperature and Mach number in the nozzle and in the space behind it are presented. The axial distribution of pressure, temperature, and Mach number has been studied. It is shown that in the case of a single-phase flow, self-similarity of gas flows is observed. The pressure fields were similar, but in a dimensionless form they coincided to each other. In this case, the identity of the velocity and temperature fields was observed at different values of the stagnation pressure. The self-similarity of the flow is violated in the zone of formation of condensed particles. The dimensions of the zones of local temperature increase, as well as the intensity of heat release, depend on the given stagnation pressure, which is reflected in the velocity characteristics of the flow.

Simulations of Bubble Formation and Oscillation Behavior in Micro-Leakage Measurement System

In the process of measuring micro-leakage based on the bubble method, the physical parameters of the liquid phase have a great impact on the formation and movement of bubbles, thus affecting the measurement accuracy of the system. Therefore, it is of great significance to study the physical parameters of the liquid phase. At present, it is difficult to independently study the parameters of the liquid phase by experimental methods. In this paper, based on the Cahn-Hilliard phase field model, a gas-liquid two-phase flow model for the expression of leakage is established to independently study the influence of different physical parameters on the formation and movement of bubbles in the measuring system. Firstly, the effects of liquid medium density, dynamic viscosity coefficient and surface tension on the initial shape (aspect ratio), the generation period and the shape oscillation of bubbles after they leave the nozzle are analyzed. Then, an experimental platform for visualization of bubbles in two-phase flow based on machine vision is built, through which the morphological parameters of bubbles in the liquid phase can be obtained in real time. Finally, the results of visualization experiment and numerical simulation are compared. The results show that the initial aspect ratio error of bubbles obtained by visual experiment and numerical simulation is 1.8%, and the average oscillation period error is 12.3%. The results are basically consistent, which proves the rationality and correctness of the mathematical model established. It is found that the liquid with larger dynamic viscosity coefficient μ and density ρ and smaller surface tension σ can be selected as the liquid medium of the measurement system. It is more conducive to the accurate expression of micro-leakage in the measurement system, and the bubble shape can quickly reach a stable state. It provides theoretical support for improving the accuracy and stability of the micro-leakage measurement system.

Процессы молекулярного переноса в жидкостных питательных средах дрожжевой и пивной отраслях промышленности Часть 2. Исследование реологических свойств водных растворов мелассы и концентрированного пивного сусла

The article is a continuation of the research in the field of comprehensive study of the properties characterizing the processes of momentum, thermal energy, and mass transfer in liquid nutrient media of biotechnological production. Experimental studies of the rheological properties for liquid nutrient media have been conducted. Beet molasses with an initial concentration of dry substances (DS) of 77.7 wt.% and concentrated malt extract of beer wort with an initial concentration of DS 81 wt.% were selected as objects of research. The temperature variation range was 10 to 70℃. The viscosity of the mentioned objects was measured with a HÖPPLER® KF 3.2 ball viscometer and also for highly viscous solutions on a Rheotest RN 4.1 viscometer, as a result of which the graphical dependences on temperature and DS concentration, as well as the gradient of shear rate were obtained. It has been established that the viscosity of these two nutrient media (beet molasses and beer wort), different in the method of obtaining the composition, has not only a similar pattern of change in the dynamic viscosity coefficient depending on temperature and content of soluble solids, but also a comparable numerical range of values. The boundaries of variation for the shear rate gradient, in which the studied objects behave as non-Newtonian fluids, from 1 to 100s-1, have been determined. The results obtained are of interest both from the point of view of fundamental science about the development of the theory of the liquid state of matter and applied, in terms of engineering calculations and the design of biotechnological equipment.

Modern Bitumen Oil Mixture Models in Ashalchinsky Field with Low-Viscosity Solvent at Various Temperatures and Solvent Concentrations

The article analyzes the modern theory and practice of pipeline transport of bituminous oil together with low-viscosity solvent. In addition, a detailed analysis of the rheological models of non-Newtonian fluids is carried out, which establishes a number of assumptions on the rheology model selection algorithm currently in use (limited number of rheological models, variability in model coefficient assignment, etc.). Ways of their elimination are proposed. Dependencies for determination of the dynamic viscosity coefficient of binary oil mixtures are investigated. Calculation of the parameters of the bituminous oil mixture with solvent is considered. Complex experimental studies on rheology mixture models of bituminous oil and solvent on the example of the Ashalchinsky field (Russia, Tatarstan) in a wide range of temperatures and concentrations of the solvent are conducted. A two-dimensional field of rheological models of the oil mixture is constructed, which makes it possible to determine the rheological model of the pumped oil mixture depending on the solvent concentration and the temperature of the mixture. Formulas for forecasting the rheological properties of the oil mixture on the basis of statistical processing of the results of experimental studies are theoretically substantiated. It is proven that the viscosity of binary oil mixtures in the Newtonian fluid field should be determined by a modified Arrhenius equation. The proposed models with a high degree of accuracy describe the rheological properties of the oil mixture. It is shown that in the case of complex mixtures, not one rheological model should be applied, but their hierarchy should be established depending on the solvent concentration and temperature.

Examining rheological behavior of CeO2-GO-SA/10W40 ternary hybrid nanofluid based on experiments and COMBI/ANN/RSM modeling

In this study, the rheological behavior and dynamic viscosity of 10W40 engine oil in the presence of ternary-hybrid nanomaterials of cerium oxide (CeO2), graphene oxide (GO), and silica aerogel (SA) were investigated experimentally. Nanofluid viscosity was measured over a volume fraction range of VF = 0.25–1.5%, a temperature range of T = 5–55 °C, and a shear rate range of SR = 40–1000 rpm. The preparation of ternary-hybrid nanofluids involved a two-step process, and the nanomaterials were dispersed in SAE 10W40 using a magnetic stirrer and ultrasonic device. In addition, CeO2, GO, and SA nanoadditives underwent X-ray diffraction-based structural analysis. The non-Newtonian (pseudoplastic) behavior of ternary-hybrid nanofluid at all temperatures and volume fractions is revealed by analyzing shear stress, dynamic viscosity, and power-law model coefficients. However, the nanofluids tend to Newtonian behavior at low temperatures. For instance, dynamic viscosity declines with increasing shear rate between 4.51% (at 5 °C) and 41.59% (at 55 °C) for the 1.5 vol% nanofluid. The experimental results demonstrated that the viscosity of ternary-hybrid nanofluid declines with increasing temperature and decreasing volume fraction. For instance, assuming a constant SR of 100 rpm and a temperature increase from 5 to 55 °C, the dynamic viscosity increases by at least 95.05% (base fluid) and no more than 95.82% (1.5 vol% nanofluid). Furthermore, by increasing the volume fraction from 0 to 1.5%, the dynamic viscosity increases by a minimum of 14.74% (at 5 °C) and a maximum of 35.94% (at 55 °C). Moreover, different methods (COMBI algorithm, GMDH-type ANN, and RSM) were used to develop models for the nanofluid's dynamic viscosity, and their accuracy and complexity were compared. The COMBI algorithm with R2 = 0.9995 had the highest accuracy among the developed models. Additionally, RSM and COMBI were able to generate predictive models with the least complexity.

Impact of Moisture Content on the Elasto-Viscoplastic Behaviour of Rammed Earth Wall: New Findings

The influence of hydric state on the elasto-viscoplastic behaviour of a unstabilised rammed earth (URE) wall has yet to be studied in the literature. This paper presents an experimental campaign on a rammed earth wall. The aim is to evaluate the link between the mechanical properties (including viscosity) and the varying hydric state inside the drying wall after manufacture. Cyclic axial compression and stress relaxation tests were carried out for this purpose. A compression test was conducted up to 0.1 MPa, followed by a stress relaxation test. These tests were periodically performed over 32 weeks. In addition, the hydric state inside the wall was monitored by humidity sensors. The results show that both the elastic modulus and the dynamic viscosity coefficient increase as the structure dries. A dependence of the mechanical behaviour on time is therefore found in these samples in the transient state. This can occur when the sample is in the drying or wetting phase. As rammed earth is a material particularly sensitive to water, this result is crucial for the durability of earthen constructions.

INTERRELATION OF INDIVIDUAL PAPER-FORMING PROPERTIES AND THE DYNAMIC VISCOSITY COEFFICIENT DURING THE GRINDING OF THE FIBROUS MASS

The refining process is associated with the movement of large masses of fibrous suspensions in the working bodies of refining machines, which affects both the refining process itself and energy consumption when moving the fibrous suspension. In this regard, the efficiency of refining equipment can be ensured on the basis of knowledge of the hydrodynamic processes that occur during the interaction of the working bodies of refining equipment with a fibrous suspension.
 During the flow of fibrous suspensions, the basic rheological feature is their viscosity, which makes it possible to judge the internal forces acting in the flow. This is especially important for the bladeless refining method using the “jet-barrier” installation.
 In order to most fully judge the direction of the refining process (in the direction of the transverse shortening of the fibers or in the direction of their longitudinal fibrillation), it is necessary to control the paper-forming properties of the fibrous mass and the physical and mechanical properties of the castings.
 The publication presents an analysis of the influence of the paper-forming properties of the fibrous mass on the quality of its refining, it is advisable to find the dependence of these indicators on the rheological features of the fibrous suspension flow in the refining zone, that is, to determine the relationship of the paper-forming properties of the fibrous mass with the dynamic viscosity coefficient during the flow of the fibrous suspension in the refining zone.

Analysis of Multifactor Influence Model on Energy Dissipation Rate of Rough-Strips Energy Dissipator in the Spillway Bend

The rough-strips energy dissipator (R-SED) is applied to the bottom of the spillway bend and can play the role of energy dissipation and flow stabilization. In this study, based on 18 sets of orthogonal tests and the principle of dimensional analysis, a multifactor influence model of R-SED’s energy dissipation rate was proposed. A dimensionless factor k was introduced, which can reflect the comprehensive characteristics of the geometric dimensions of R-SEDs. The multifactor influence model of the energy dissipation rate considered nine factors, including bend radius of curvature Rc, bend width B, flow velocity of the bend inlet v , R-SED’s average height hL, R-SED’s arrangement angle θ, R-SED’s arrangement spacing ∆L, fluid density ρ, dynamic viscosity coefficient μ, and gravitational acceleration g . The residual sum of squares of the model (RSS) was 6.6% and the correlation coefficient R was 83.2% (>80%), indicating the universality and feasibility of the model. The independent variables of the multifactor model of the energy dissipation rate were ranked according to the Pearson value in descending order: (ΔL/Rc) > (θ) > (B/Rc) > (hL/Rc) > (1/Fr2). This indicates that R-SEDs’ layout parameters showed larger effects on the multifactor model of the energy dissipation rate, compared with the engineering layout parameters of the spillway. The maximum relative error between the predicted value of the multifactor model and the measured value of the validation group was 6.28%, indicating good agreement. In the orthogonal tests, scenario 5 had the highest energy dissipation rate (44.83%) with k = 0.023; scenario 16 had the largest k value (0.043), with an energy dissipation rate of 40.78%. The multifactor influence model of R-SEDs’ energy dissipation rate proposed in this paper was a semi-theoretical and semi-empirical calculation formula, which can provide reference and support for similar practical engineering designs.