Mixture Flow Research Articles

АНАЛИЗ ЭКСПЛУАТАЦИОННЫХ ХАРАКТЕРИСТИК ПРИБОРОВ УЧЕТА МОЛОКА

The foreign and domestic individual milk yield accounting devices analysis is carried out. The dairy industry development’s main directions for production rate’s and milk quality increasing are given. The development of these areas is impossible without for milk collecting, accounting and primary processing. Milk accounting on modern domestic and foreign farms can be both group and individual. At group accounting, milk from cows enters into a cooling tanker, and then, through a metering device, into the tanks of vehicles for transportation for enterprises and plants processing. This is a simple and convenient method using only one milk meter, however, by this accounting method, the milking process control impossible. The individual milk yield counters’ using is important for particular cow milk yield predicting for cow health preserving due to milking cups’ absence overexposing. Also, individual milk accounting allows to separate mastitis infected milk from the healthy cows’ milk, that allows to reject only part of farmer milk producing, and not the entire batch, as it would be in the case with group accounting. A brief description of the types of sensors for individual and group milk metering from foreign and domestic producers is presented. An advantages and disadvantages of the considered milk metering devices comparative assessment is given. It is concluded that there is a necessity developing for a system that will meet the following requirements: the ability with a milk-and-air mixture working; device’s high autonomy; construction’s simplicity; high accuracy. Based on the analysis of milk meter designs, it can be argued that the most design promising should be based on the capacitive principle, when the milk-and-air mixture flow will change the electrical capacitance

Enhanced stability of a three-dimensional graphene nanosheets networks modified asphalt mixture

To date, several concepts have been developed to enhance the mechanical and service life of asphalt pavements. Additives such as graphene, carbon nanotubes, carbon fibers and carbon black are used in the hot mix asphalt (HMA) or the asphalt binder (i.e., bitumen) for higher resistance to permanent deformations such as rutting, and transverse thermal cracking due to increased traffic volumes, vehicle mass and axle loads. In this study, graphene nanosheets (GNs) were used as potential modifier of bitumen binder in the HMA. The objective of this work is to investigate the impact of GNs modified bitumen on the Marshall stability and flow of the asphalt mixture using laboratory-compacted samples. The X-ray diffraction (XRD) study revealed a diffraction peak of GNs (002) at 2θ =26.5° along the bitumen’s γ-band and 10-band, which confirm a successful dispersion of GNs into bitumen binder. Furthermore, morphological analysis showed formation of a three dimensional (3d) interconnected networks of GNs between the bitumen micro-structures which could act as bridges for increased flexural strength of the binder. The Marshall stability and flow test results indicate that the mechanical properties of asphalt mixture were influenced by the addition of GNs to the bitumen binder. At 5% by weight of GNs modified bitumen (GNs-B), the compacted hot-mix Asphalt sample showed a higher Marshall stability of 11.7 kN recording 13.6% enhancement in comparison with the asphalt mixture with pure bitumen (P-B). In addition, when GNs-B was used, a lower flow of 1.4 mm was recorded which is desirable to prevent rutting and other forms of failure in asphalt pavements. This study underlines that adding GNs into asphalt binders such as bitumen could play a key role in enhancing the performance of asphalt pavements, which in turn extends their service life and saves maintenance expenses.

АНАЛИЗ НАПРАВЛЕНИЙ МОДЕРНИЗАЦИИ ПОТОЧНОГО УСТРОЙСТВА АНАЛИЗА ПАРАМЕТРОВ КАЧЕСТВА МОЛОКА

Currently, mechanization and robotization of modern dairy farms require the development of advanced technologies for assessing the quality of manufactured products. Information on the content of milk components such as fat, protein, lactose, somatic cells, progesterone and amino acids serves as the basis for assessing the quality of milk, as well as diagnosing the nutritional balance and clinical condition of cows. (Research Purpose) The research purpose is studying the potential possibilities of upgrading a flow scatterometric device for express analysis of milk quality parameters to ensure laboratory and field tests in conditions as close as possible to production operation. (Materials and methods) The current parameters of the device are considered and the potential possibilities of modernization are analyzed. (Results and discussion) The analysis of the modernization of the flow scatterometric device for express analysis of milk quality parameters revealed 4 ways: modernization of radiation sources; modernization of radiation receivers; modernization of the measuring chamber and its flushing process; modernization of the bracket and housing. Methods of modernization are proposed in all identified areas. (Conclusions) In the course of the study, it was determined that the current device is not sufficiently adapted to the conditions of industrial operation, therefore, to adapt and improve the efficiency of its operation, proposals for modernization were formed: integration of a second radiation source in the ultraviolet range, which will allow detecting protein molecules in the flow of milk-air mixture; the use of a CCD matrix as a radiation receiver for the transition to continuous information about the light scattering indicatrix; reduction of the discharge volume for measurements at a low filling level of the milk hose; development of an additional protective casing for moisture protection and vibration resistance.

Binary mixture convection in a horizontal channel under the Soret effect action

The mathematical model describing stationary flow of binary liquid mixture is under consideration. The exact solution of the equations of convective heat and mass transfer is constructed for the special form of the functions of temperature and concentration. All possible statements of boundary value problems are studied in order to analyse thermal diffusion separation of binary mixture in a long horizontal channel with rigid walls. It is discovered that only one of the statements (at inhomogeneous heating of both rigid walls) leads to feasible results. With the help of the constructed solution for the mentioned boundary value problem the effect of layer thickness, given flow rate and action of gravity force on the separation process, is analysed.

Flame development in prechamber assisted engine: High-speed PLIF

Prechamber-assisted combustion reduces emissions and improves engine performance through lean and knock limit enhancement. The spark plug ignition is replaced by multiple, high-temperature, radical-rich jets that entrain and ignite the main chamber charge, enabling the engine to operate at leaner air–fuel mixtures. Current work reports first cycle resolved planar laser-induced fluorescence (PLIF) measurements following the flame development process, starting from the mixture formation inside the prechamber to the post-combustion jets in the main chamber. The mixing and flame development inside the prechamber is visualized at 100 kHz with Acetone PLIF using an inventive engine-mounted optical prechamber (OPC) setup. Following the burning (/burned) prechamber jet interaction with the unburned main chamber, the mixture is imaged using the fuel and flame tracer (FFT) PLIF approach. The innovative 50 kHz FFT-PLIF approach is based on the fluorescence of acetone as fuel (unburned) and combustion-generated SO2 as a flame (burned) tracer with 266 nm laser excitation. The main chamber is fueled with premixed methanol seeded with 6.8 acetone and 2.6% (m/m) di-tert-butyl disulfide (DtBDS) while prechamber is injected with methane at 6 bar using solenoid and check valve assembly. The flow of the main chamber mixture into the prechamber creates a turbulent jet inside the prechamber. The inflow increases as the pressure ratio drops, generating significant recirculation inside the prechamber. Partially oxidized products remain near the top center of the prechamber even as the flame propagates through the throat. Combined flame and fuel images reveal the dynamics of the interaction layer between the prechamber jet and the main chamber fuel–air mixture.

Effect of mixing chamber structure on the performance of adjustable ejector

The study employs numerical simulation method to analyze performance of an adjustable ejector, with a specific focus on the influence of the structure dimension of mixing chamber. R41/R1234yf refrigerant is used as the working medium in the study. The primary and secondary flow inlets are set at the pressure of 1.4 MPa and 0.2 MPa, respectively, along with temperature of 353.15 K and 288.15 K corresponding. The outlet pressure of the ejector is 0.3 MPa. The simulation results show that optimal mixing chamber diameter within a range from 14.7mm to 18.7mm exists for obtaining peak adjustable ejector performance. Maximum entrainment ratio of 0.59 is obtained when cone diameter ratio is 65% and diameter of the mixing chamber is 15.7mm. Furthermore, the optimal mixing chamber length within range from 24mm to 220mm exists for obtaining peak adjustable ejector performance. Maximum entrainment ratio of 0.624 is obtained when cone diameter ratio is 76% and length of the mixing chamber is 88 mm. Therefore, it is crucial during designing process of the mixing chamber to ensure the complete fluid mixture and minimal flow resistance.

Extensive analysis of the applicability range of the linear kinetic approaches in the case of the pressure driven gas mixture flows

The study of gas mixture flows through micro- and macro-channels remains a very attractive area for theorists and experimentalists worldwide, mainly due to their great practical applicability in several aspects of science and industry. The present work includes a comparative study between the linear (McCormack model) and the nonlinear (DSMC method) kinetic theories of binary gas mixture flows through channels over a wide range of the involved parameters. The results show that the McCormack model is a reliable kinetic model for predicting the gas mixture flow behavior. Specific criteria with respect to the applicability range of the linear kinetic theory of short and long capillaries are proposed. The analysis shows that the separation phenomenon remains strong even in the case of small pressure drops. The applicability range of the linear kinetic theory for binary gas mixture flows driven by large pressure drops is obtained to be smaller compared to that of single gases but still wide enough covering a wide range of pressure ratios. Furthermore, the present work shows that the long capillary theory remains a very powerful tool for studying the gas mixture flow behavior under weak and strong nonequilibrium conditions. This work provides a kinetic database of the linear kinetic data (as supplementary material), which until today is still missing from the literature, and as it is shown throughout this work, it can be used far beyond the restrictions defined by the linear kinetic theory.

Numerical Evaluation of Harmful Consequences after Accidental Explosion at a Hydrogen Filling Station

Abstract This study aims to present computational technology that can be used to evaluate numerically the harmful environmental consequences caused by an accidental hydrogen release from failed high-pressure dispensing cylinders and its explosion at a vehicle hydrogen filling station. A coupled problem of a hydrogen explosion products expansion in the atmospheric ground layer and a harmful explosion pressure wave shock impact on service personnel and infrastructure buildings at an accident site is solved by means of computer experiment simulation series. A spatial time-dependent model of compressible hydrogen-air mixture flow is used to obtain pressure history in calculation area in order to assess maximum overpressure in control points of human possible locations and on building surfaces exposed to hydrogen blast wave impact. A deterministic impact consequences model is based on comparing maximum overpressure values extracted from the mathematical model with threshold ranges corresponding to certain degrees of human damage and infrastructure destruction. The presented computer technology allows safety experts to identify potentially dangerous zones by means of mathematical modelling and recommend effective protection measures to mitigate negative consequences of explosions.

The effect of pipeline parameters of machines for applying liquid complex fertilizers on the drip-air mixture quality

The article is devoted to the study of a drip-air mixture flow through pipelines, namely, the determination of total pressure losses based on known values of the flow rates of the constituent phases or the loss coefficients of the constituent phases. The authors conclude that the conditions for introducing the drip-air mixture into the pipes do not affect the size of the flow structure stabilization area. It has been found that for small values of the air and liquid flow rates, the diameter and length of the pipeline, as well as its position, have a very significant effect on the flow structure of the two-phase mixture and on the average diameter of the droplets. For each pipeline length and diameter, there is a pulsation flow mode only at certain values of the air and liquid flow rates (Gv/Gl), moreover, the larger the diameter and length of the pipeline, the later the pulsation flow mode occurs. At high values Gv/Gl, the position, length, and diameter of the pipeline do not have a noticeable effect on the flow shape, the flow has a finely dispersed structure, pressure pulsation is practically absent.

Comparative study of heat transfer in apparatuses with turbine and blade agitators

In the framework of this research, modeling of flows and heat transfer in apparatuses with turbine and blade agitators using the ANSYS CFX software package has been carried out. The purpose of the work is to create digital prototypes of apparatuses with stirring devices to improve the effectiveness of technological processes of various chemical and petrochemical industries. Modeling was carried out on the basis of three different objectives, including the processes of water heating and mixture of water with glycerol. In each objective, the heating and circulation characteristics of the liquid during mixing using turbine and blade agitators were investigated. The effects of parameters such as apparatus wall temperature, water and mixture flow rate, rotation speed and agitator type on the time characteristics of reaching steady-state were evaluated. The simulation results demonstrated that turbine and blade agitators provide more efficient mixing and heating of the liquid compared to blade agitators, all other conditions being equal. Fluid temperatures reached higher values in a shorter time when turbine agitators were used, making them preferable for processes where intensive mixing and rapid heating are required. This approach can be useful to optimize mixing processes on production lines and improve the energy efficiency of production facilities.

Suitability of different machine learning methods for high-speed flow modeling issues

In the present study, machine learning algorithms are applied for modeling transport coefficients in strongly nonequilibrium reacting gas flows. As a model case, the problem of a hypersonic flow of a five-component air mixture around a sphere is considered. Various approaches for an application of machine learning methods, such as linear regression, k-nearest neighbors, support vector machine, regression tree, random forest, gradient boosting, and neural network (multilayer perceptron) are investigated. For the transport coefficients regression modeling the combination of machine learning methods with the finite volume method is constructed. The machine learning regressors are trained on the accurate numerical data given by one-temperature approach of the kinetic theory. The results of trained models are compared with approximate formulae of Blottner-Eucken-Wilke model. The results of different machine learning methods are analyzed in terms of the relationship between the obtained accuracy of calculations and the overall speed of calculations. The overall time of dataset formation and model training is estimated. The design of the constructed multilayer perceptron is discussed. The machine learning methods considered in the article can be used for the engineering problem such as design of high-speed aircraft, as well as for modeling of flows around complex shape bodies.

Experimental study of the natural deposition of submicron aerosols on the surface of a vertical circular tube with non-condensable gases

This paper constructed an experimental platform containing a space heat exchanger tube, and performed aerosol deposition experiments under different deposition mechanisms. The objective was to study the effect of the passive containment heat removal system on the natural deposition of submicron aerosols during post-accident operation of severe accidents. By controlling the variables, we obtain the impact of gravity deposition, thermophoretic, and diffusiophoresis deposition mechanisms on submicron aerosols in the presence of a space heat exchanger tube using the experimental data stripping method. The study found that the gravitational settling rate of aerosols in two-phase mixtures at the same temperature and pressure is about 1.5 times higher than in dry air. Although submicron aerosols are subject to thermophoretic settling in the presence of temperature differences, due to the small surface area of the heat exchanger tube, the potential thermophoretic sedimentation accelerating effect on the particles can be ignored if the mixed gas temperature difference is within 2000 K/m. Unlike the steam condensation on the flat plate surface, when vapor condenses on the heat exchanger tube surface, as the steam proportion and condensation rate increase, it is easy to cause the accumulation of non-condensable gas. This phenomenon can reduce the reverse diffusion slip of the particles and enhance the influence of Stefan flow in the diffusionphoresis deposition process. The above effects make the experimental results of aerosol diffusiophoresis deposition closer to the SF model when the vapor fraction is 70 %. When the vapor fraction is 50 %, the predictions of the WM model, which considers the average mass flow of the gas mixture, are more applicable. When the condensation rate continuously increases, the convective mass transfer of vapor condensation will be enhanced, and the deposition rate of particles will be further enhanced.

Physiochemical properties of the binary liquid mixtures of 2-methyl-2,4-pentanediol with selected di- and tri-chloro-substituted benzene and correlation with the Jouyban–Acree model at various temperatures

ABSTRACT Excess molar volume, excess isentropic compressibility, deviation in viscosity and excess Gibbs free energy for the activation of viscous flow for binary mixtures of 2-methyl-2,4-pentanediol (MPD) with 1,2-dichlorobenzene (1,2-DCB), 1,3-dichlorobenzene (1,3-DCB) and 1,2,4-trichlorobenzene (1,2,4-TCB) components selected compositions are determined from the measured values of densities (ρ), speeds of sound (u) and viscosities (η) of pure components and their mixtures from 303.15 K to 313.15 K. The results are analysed in terms of intermolecular interactions or hydrogen bonding or hetero-association interactions in the binary mixtures. The Prigogine–Flory–Patterson (PFP) theory is applied to identify the predominant molecular interaction. The results of Jouyban–Acree model are discussed in terms of mean relative deviation (MRD) and individual relative deviation (IRD) between the calculated and experimental densities, speeds of sound and viscosities as accuracy criteria.

Анализ внезапного выброса газоугольной смеси из полости конической формы, сформированной в процессе выброса

Indispensable attributes in underground coal mining are methane and coal dust of various particle sizes. When they are mixed, coal-gas mixtures are formed, predisposed to various hazardous and extremely hazardous gas-dynamic phenomena, primarily to sudden emissions, accompanied by formation of cavities in the coal massif and intensive release of coal-gas mixtures from these cavities into the mine workings. The article deals with the problem of a one-dimensional stationary flow of a gas-coal mixture in an underground cone-shaped cavity formed during a sudden release. The Euler equation of motion and the continuity equation are used as the basic equations. As a result of their transformation, an ordinary differential equation of the first order is obtained, for which the Cauchy problem is formulated. The solution to the Cauchy problem is a transcendental equation with respect to the desired Mach numbers. The roots of the transcendental equation are calculated using the MathCAD mathematical software suite. Upon finding the Mach numbers, the remaining parameters of the mixture are determined, i.e. the pressure, density and temperature of the gas-coal mixture at any point in the conical region, including their critical values. Graphs are constructed that were used as the basis to establish some regularities of the one-dimensional stationary flow of a gascoal mixture in a conical region. In particular, it was found that with an increase in the Mach number, parameters of the gas-coal mixture decrease non-linearly, and with an increase in the Poisson's adiabatic index, the pressure and temperature decrease, and the density increases.

Relating early-age hydration and flow loss of mortar prepared with manufactured sand

Cement-based materials prepared with manufactured sand can exhibit quick loss of fluidity. However, the estimation of the flow loss remains difficult given the variable contents and physiochemical properties of the microfines in various sands. This paper studies the fluidity loss of mortar mixtures made with different manufactured sands varying in mineral composition and content of microfines. The effect of microfines on accelerating the early-age hydration of cement before the deceleration period was evaluated by quantifying the generation of early hydration products. Test results show that the growth of yield stress corresponding to the loss of mini-slump flow of mortar mixtures were mainly determined by the formation of early hydration products, in addition to the volume fraction and packing density of aggregate grains and powder particles. An approach was then proposed that can assess the loss of mini-slump flow of mortar mixtures prepared with manufactured sand, regardless of the type and content of the microfine materials in the sand.

Research of an oblique detonation wave in a limited area

This work presents the results of two-dimensional numerical simulation of processes, arising from the interaction of an incoming flow of a well-mixed stoichiometric hydrogen-air mixture with a wedge in a bounded region at high Mach velocities using Navier-Stokes type equations taking into account chemical interactions. The Mach number of the incoming flow from 9 to 12 were considered. Various wave configurations were obtained depending on the velocity of the incoming flow. For the flow Mach number of 9, the presence of a detonation wave perpendicular to the flow was obtained. For high flow velocities, another similar wave configuration of the same type was obtained.

Modeling and optimization of steady flow of natural gas and hydrogen mixtures in pipeline networks

We extend the canonical problems of simulation and optimization of steady-state gas flows in pipeline networks with compressors to the transport of mixtures of highly heterogeneous gases injected throughout a network. Our study is motivated by proposed projects to blend hydrogen generated using clean energy into existing natural gas pipeline systems as part of efforts to reduce the reliance of energy systems on fossil fuels. Flow in a pipe is related to endpoint pressures by a basic Weymouth equation model, with an ideal gas equation of state, where the wave speed depends on the hydrogen concentration. At vertices, in addition to mass balance, we also consider mixing of incoming flows of varying hydrogen concentrations. The problems of interest are the heterogeneous gas flow simulation (HGFS), which determines system pressures and flows given fixed boundary conditions and compressor settings, as well as the heterogeneous gas flow optimization (HGFO), which extremizes an objective by determining optimal boundary conditions and compressor settings. We examine conditions for uniqueness of solutions to the HGFS, as well as compare and contrast mixed-integer and continuous nonlinear programming formulations for the HGFO. We develop computational methods to solve both problems, and examine their performance using four test networks of increasing complexity.

DETERMINATION OF POWER LOSSES DUE TO PERIODIC COMPRESSION-EXPANSION OF THE OIL-AIR MIXTURE BETWEEN THE TEETH OF GEARS. PART 1. MATHEMATICAL MODEL

The simultaneous contact of two pairs of teeth between their active profiles creates a closed volume of the oil-air mixture. Reducing this volume leads to the occurrence of such a negative phenomenon as periodic compression and expansion of the oil-air mixture in volume. At high gear rotation speeds, a significant increase in the pressure of the oil-air mixture is observed and, as a result, additional vibration of the gearing occurs. The oil-air mixture outflow rate can reach the speed of sound, which causes additional noise during gear operation, and at high rotational speeds, a hydraulic shock occurs in the space closed between the pinion and gear teeth, resulting in cavitation. By representing the helical gear as a set of spur gears displaced relative to each other in the tangential direction, it simplified the mathematical model to describe thermodynamic processes in a series of isolated cavities. The following variants are considered: a) the first cavity in the direction of engagement is connected to the environment on one side and to the next second cavity on the other side; b) some i-th cavity is connected to the cavities i - 1 and i + 1, respectively; c) the edge cavity N is connected to the previous cavity N - 1 and the environment. Thus, a mathematical model of the periodic compression-expansion of the oil-air mixture in the space closed between the teeth is presented, which considers the cross-sectional areas of the axial and radial flows of the oil-air mixture, the ambient pressure of the space closed between the teeth, the velocity of the radial flow of the oil-air mixture, the instantaneous volume of the elementary cavity closed between the teeth, and the current pressure in the cavity. Keywords: power losses, oil-air mixture, periodic compression-expansion, toothed gears, mathematical model, hydrodynamic model

Investigation of Digestion Processes in the Stomach and Duodenum using Computational Fluid Dynamics Model

The stomach and intestines play an important role in homogenizing the contents of the tract, mixing food with enzymes. The study of digestion processes in a fed state remains difficult by experimental methods. Using computational fluid dynamics models it is possible to obtain flow characteristics at any point in the computational domain. At the previous stages of research, we developed a model to describe the flow of a multiphase multicomponent mixture in the antroduodenum, taking into account the processes of mass transfer between phases, biochemical reactions, mass sources and effluents. In this article, we propose an improvement of the model for describing the multiphase flow in the whole stomach and duodenum, taking into account the gas phase. The mathematical formulation of the problem includes the balance equations of mass and momentum for a multiphase medium with mass sources. Boundary conditions take into account the peristalsis of the tract. In numerical experiments we studied the influence of the density of food particles on the distribution of volume fractions of phases, mass fractions of food components and enzymes, pH level in the digestive tract. In the future, it is necessary to continue working with the rheological properties of the flow.

Numerical analysis of sodium-argon two-phase flow in narrow channels under severe accident conditions in pool type SFR

A two-phase flow model for sodium-argon mixture flow through the reactor vessel head penetrations under the energetic core disruptive accident in a sodium fast reactor (SFR) is presented. The model evaluates the total sodium mass in sodium-argon mixture released to the reactor containment building (RCB) through penetrations. The driving pressure at the penetration entrance is given as input. The two-phase frictional and local pressure drops, inertial and piezo-metric heads are accounted for in the model. Depending on the argon volume fraction, either a homogenous or separated flow approach is adopted to evaluate the mixture flow. Reactor-scale analysis show that the presence of argon in vessel head penetrations can significantly mitigate the total sodium release mass during the slug impact phase. Also, the two-phase frictional pressure drop plays a mitigating role and needs to be included in the model formulation to avoid overestimation of the sodium release mass. Fluid-structure interaction effects such as vessel head bending and hold-down bolt elongation have negligible influence on sodium release mass as long as the deformations are within the elastic limit. The model is conceived to be part of an integrated code system to evaluate the sodium fire and the maximum RCB pressure under severe accident conditions in a pool-type SFR.