Multiphase Systems最新文献

{"title":"On the theory of hydrate formation decomposition under thermal influence","authors":"V. Shagapov, M. Davletshina","doi":"10.21662/mfs2019.4.031","DOIUrl":"https://doi.org/10.21662/mfs2019.4.031","url":null,"abstract":"A mathematical model of the process of decomposition of gas hydrate during heat exposure is proposed and developed. Based on the proposed technological scheme and the corresponding theoretical model, the problem of the action of a heat source on a porous layer of finite length, initially saturated with methane hydrate, is considered. The task describes the heating and simultaneous extraction of gas into a combined well. According to the adopted scheme, a coolant in the form of hot water is supplied to the annular channel, and the internal well communicates with the formation and gas is produced there, which was formed during the hydrate decomposition as a result of thermal exposure. The influence of the temperature of the heat source on the evolution of thermal fields around the well, on the nature of the motion of the phase transition boundary, is studied, and the law of its motion is obtained. The heat consumption for heating the formation and the evolution of gas output over the considered time interval at various values of the heating temperature and pressure drop are analyzed. The dynamics of the gas mass flow rate and the energy efficiency of methane production at various values of the temperature difference between the reservoir and the fluid injected into the heat pipe are revealed. A quasistationary solution is obtained that corresponds to the case when a pressure is maintained in the well equal to the equilibrium value for the initial temperature of the gas hydrate formation. The dependence of the energy efficiency of the proposed method of gas production on the porosity of the formation is analyzed. It was established that with a twofold increase in the hydrate content of the formation, this value grows by about ten percent. The obtained solutions make it possible to determine the most favorable heat exposure regimes. Moreover, this solution is in good agreement with the numerical results obtained by a more general theoretical model.","PeriodicalId":309215,"journal":{"name":"Multiphase Systems","volume":"1 1","pages":"0"},"PeriodicalIF":0.0,"publicationDate":"1900-01-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"122430143","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}

{"title":"Two-dimensional dynamic model of the interaction of a fluid and a piezoelectric bending actuator in a plane channel","authors":"I. Nasibullayev, O. Darintsev","doi":"10.21662/mfs2019.4.029","DOIUrl":"https://doi.org/10.21662/mfs2019.4.029","url":null,"abstract":"The paper proposes a two-dimensional computer model of the fluid flow in a plane channel under the action of an applied pressure drop with a flat ceramic piezoelectric actuator immersed in it, bending in the transverse direction in proportion to the applied electric voltage. A mathematical model of the coupled liquid-piezodrive system in variational form for numerical simulation by the finite element method is proposed. Since the assignment of the Dirichlet boundary conditions for displacement in this problem, is difficult, an equivalent piezo actuator deformation scheme using the Neumann boundary conditions is constructed. The deformations and equivalent stresses of von Mises on a piezo actuator are calculated. The influence of the geometry of the channel and the hydrodynamic resistance formed by the piezo actuator on the dynamics of the fluid flow is analyzed. An algorithm is proposed for adaptive dynamic remeshing of the channel computational mesh under deformations exceeding the size of finite elements. With a symmetric control signal supplied to the piezoelectric actuator, the asymmetry of the geometry leads to a violation of the symmetry of the fluid flow within the period, both in terms of fluid flow rate and in time. In the absence of a pressure drop at low frequencies of the oscillations of the piezoelectric element (of the order of the inverse relaxation time of the velocity), the period-average liquid flow rate is nonzero and increases with increasing frequency. In the presence of an external pressure drop along the layer, the average liquid flow rate is proportional to the pressure drop; at low frequencies, it is inversely proportional to the frequency; with increasing frequency, it reaches saturation. Based on the results of numerical modeling, various variants of new microfluidic technical devices generating a fluid flow using a piezoelectric bending actuator are proposed: a micropump creating a closed-circuit flow; fluid flow regulator and fluid volume dispenser.","PeriodicalId":309215,"journal":{"name":"Multiphase Systems","volume":"49 1","pages":"0"},"PeriodicalIF":0.0,"publicationDate":"1900-01-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"127855067","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}

{"title":"Elements of the theory of forced mixing of oils in tanks","authors":"V. Shagapov, E. Galiakbarova","doi":"10.21662/mfs2019.2.014","DOIUrl":"https://doi.org/10.21662/mfs2019.2.014","url":null,"abstract":"To prepare for transportation at the fields, light and heavy oils are mixed with the help of jet mixers, which are injection devices that are installed in the receiving and distributing nozzle inside the tank. The work considers the simplest technological mixing scheme. The basic equations are presented that describe the processes of mixing light and heavy oils in a mixer, in which the light oil stream is the working stream, and the source stream in the heavy oil tank is the injected stream. The characteristic equation of the mixer is obtained. A system of equations is presented that describes the trajectory of the center line of the jet, changes in oil composition and average velocity along the jet. An example of a mixer, which is used in practice in a reservoir of the PBC 2000 type, is considered. Based on the characteristic equation for the known pressure drop of the working and injected flows, as well as the ratio of the sections of the working nozzle and the output section of the mixing chamber, the mixer injection coefficient is found. The calculated graphs of the characteristics of a turbulent flooded jet in an oil field oil storage tank are presented. From the graphs it follows: 1) there is a complete alignment of the concentration of the injected oil mixture with the concentration of heavy oil in the tank; 2) the speed of the jet decreases at a distance of the order of several meters to a value exceeding the minimum fishing speed known from the practice of liquidating bottom sediments. The main role of the mixer when mixing oils is that due to the injection of heavy oil from the reservoir, forced circulation flows are formed that exclude the formation of stagnant zones and the precipitation of solid inactive deposits.","PeriodicalId":309215,"journal":{"name":"Multiphase Systems","volume":"50 1","pages":"0"},"PeriodicalIF":0.0,"publicationDate":"1900-01-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"126837243","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}

{"title":"Determination of the dimensions of the cylindrical weight at the end of the rod","authors":"A. A. Aitbaeva","doi":"10.21662/mfs2019.3.028","DOIUrl":"https://doi.org/10.21662/mfs2019.3.028","url":null,"abstract":"This article discusses free transverse vibrations of a homogeneous rod. The left end of the rod is clamped, and a cylindrical weight is concentrated at the right end. The eigenfrequencies of the rod vibration are known. The purpose of this work is to determine the parameters of the end cylindrical weight of the rod (mass, moment of inertia, length and radius) by the natural frequencies of the rod vibrations. We use a partial differential equation derivative of the fourth order to solve this problem. This equation and boundary conditions are reduced to a spectral problem. To find the mass and moment of inertia of the weight, the «Method of an additional unknown» was applied. In the characteristic determinant of the spectral problem, there are terms that contain products of unknown coefficients. The essence of the «Method of an additional unknown» is that some of these products are proposed to be considered new additional unknowns, through which the rest can be expressed. It is shown that the mass and moment of inertia of the weight can be found using the three natural frequencies of the rod vibrations. Formulas for finding the length and radius of a cylindrical weight are obtained, and corresponding examples of finding unknown parameters are considered.","PeriodicalId":309215,"journal":{"name":"Multiphase Systems","volume":"115 23","pages":"0"},"PeriodicalIF":0.0,"publicationDate":"1900-01-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"132772039","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}

{"title":"Synthesis of new microfluidics models in the research in the “Robotics and Control in Technical Systems” laboratory","authors":"O. Darintsev","doi":"10.21662/mfs2022.1.007","DOIUrl":"https://doi.org/10.21662/mfs2022.1.007","url":null,"abstract":"Robotics is an interdisciplinary scientific direction, therefore, when solving a number of problems, it becomes necessary to conduct research that is typical for other areas of science. So, when synthesizing new types of equipment in the „Robotics and Control in Technical Systems” laboratory, more accurate characteristics of individual components and assemblies were required, which ultimately led to a whole cycle of work on microfluidics. Of particular interest in the work performed is the development of new microdevices, since this involves the construction of a single complex of new mathematical and computer models that link hydrodynamics, elasticity theory, heat transfer process, parametric optimization and control theory. The first models were obtained that describe the movement of a piston fixed by an elastic spring in a pipe, taking into account the influence of dry viscous types of friction. By the method of factorial computational experiment, analytical dependencies were obtained for the main part of the fuel dosing unit — servo piston. Next, mathematical and computer models were built to analyze the fluid flow through a channel with variable geometry. Based on the simulation results, the design of a new micromechanical device — a piezoelectric micropump consisting of an elastic tube and annular piezoelements located on it, the sequential oscillation of which creates a non-zero average fluid flow, was refined. In the course of the adaptation of the model, an effective design of the device for smoothing fluid flow pulsations was obtained. These devices were developed and calculated for use in the liquid cooling system of capillary microgripper. A parametric analysis of the process of cooling the hot side of the Peltier element of the microgripper was carried out with a change in the following gripper parameters: the size and shape of the radiator, the coolant flow rate and the heat transfer coefficient. The results of the analysis of temperature fluctuations of the radiator under unsteady fluid flow confirmed the expected dependences of the cooling efficiency on the chosen geometry of the radiator and low-frequency fluid flow fluctuations.","PeriodicalId":309215,"journal":{"name":"Multiphase Systems","volume":"46 1","pages":"0"},"PeriodicalIF":0.0,"publicationDate":"1900-01-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"132806834","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}

{"title":"Research of eigenfuctions perturbation of the transverse component velocity thermoviscous liquids flow","authors":"A. Nizamova, V. Kireev, S. Urmancheev","doi":"10.21662/mfs2019.2.018","DOIUrl":"https://doi.org/10.21662/mfs2019.2.018","url":null,"abstract":"The viscous model fluid flow in a plane channel with a linear temperature profile is considered. The problem of the thermoviscous fluid flow stability is solved on the basis of the previously obtained generalized Orr–Sommerfeld equation by the spectral method of decomposition into Chebyshev polynomials. We study the effect of taking into account the linear and exponential dependences of the viscosity of a liquid on temperature on the eigenfunctions of the hydrodynamic stability equation and on perturbations of the transverse velocity of an incompressible fluid in a plane channel when various wall temperatures are specified. Eigenfunctions are found numerically for two eigenvalues of the linear and exponential dependence of viscosity on temperature. Presented pictures of their own functions. The eigenfunctions demonstrate the behavior of the transverse velocity perturbations, their possible growth or attenuation over time. For the given eigenfunctions, perturbations of the transverse flow velocity of a thermoviscous fluid are obtained. It is shown that taking the temperature dependence of viscosity into account affects the eigenfunctions of the equations of hydrodynamic stability and perturbations of the transverse flow velocity. Perturbations of the transverse velocity significantly affect the hydrodynamic instability of the fluid flow. The results show that when considering the unstable eigenvalue over time, the velocity perturbations begin to grow, which leads to turbulence of the flow. The maximum values of the eigenfunctions and perturbations of the transverse velocities are shifted to the hot wall. It is seen that for an unstable eigenvalue, the perturbations of the transverse flow velocity increase over time, and for a stable one, they decay.","PeriodicalId":309215,"journal":{"name":"Multiphase Systems","volume":"2 1","pages":"0"},"PeriodicalIF":0.0,"publicationDate":"1900-01-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"134574400","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}

{"title":"The impact of an additional inlet point on the hot outlet side on the vortex tube productivity","authors":"L. Privalov, C. Mikhaylenko","doi":"10.21662/mfs2019.3.024","DOIUrl":"https://doi.org/10.21662/mfs2019.3.024","url":null,"abstract":"Based on numerical simulation, the production of cold and hot air on a modified countercurrent vortex tube is studied. A feature of the modification under study is an additional air inlet area along the axis of the pipe from the hot outlet side. An additional point of blowing air is designed to redistribute the gas flows at the cold and hot outlets. Computational experiments were performed in the OpenFOAM software package using the sonicFoam solver based on the k−ε turbulence model under the assumption of an ideal gas. The dependence of the flow rate and temperature at the cold and hot outlets for different lengths of the main channel of the vortex tube was studied. For all considered pipe lengths, finite-volume grids were prepared in which the rectangular shape of the cells was preferably observed and their excessive stretching was avoided. To speed up the simulations, MPI technology was used; spatial decomposition of the original mesh was performed by decomposePar utility into equal parts along the pipe. This approach allowed us to reduce the computation time by approximately 3.5 times when running on six processes. The results of parallel modeling were combined with the reconstructPar utility and further processed by a Python program written using the vtk library. Thus, average values of the main physical characteristics by time and space at the cold and hot outlets were obtained. Results are discussed that demonstrate the effect of the vortex tube length on temperature and air flow at the respective outputs. The behavior of its main characteristics, non-standard for a vortex tube, is shown, an assumption is made about the reason for this behavior: the collision of very fast flows makes instability. Preliminary conclusions are made about choosing the effective length of the vortex tube with an additional air inlet channel at which the ratio of air temperature at the hot and cold outlets is the largest.","PeriodicalId":309215,"journal":{"name":"Multiphase Systems","volume":"63 1","pages":"0"},"PeriodicalIF":0.0,"publicationDate":"1900-01-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"123316954","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}

{"title":"To the theory of determining the location of hydrate deposits in gas pipelines by acoustic sounding","authors":"V. Shagapov, E. Galiakbarova, Z. R. Khakimova","doi":"10.21662/mfs2019.3.022","DOIUrl":"https://doi.org/10.21662/mfs2019.3.022","url":null,"abstract":"Evolution of pressure perturbations propagating in pipeline filled with gas-and-drop medium representing “wet” methane at temperature below dew point and having damaged section, in form of extended narrowing of channel due to hydrate plug, is investigated. Hydrate formation is due to the presence of water (or its vapours) and gas, the components of which dissolve in water under certain conditions form a solid phase. Hydrate deposits help to reduce the cross-country capacity of gas pipelines and therefore their detection is a pressing task. It is proposed to solve the problem using acoustic methods. For this purpose mathematical model of propagation of acoustic waves in long-wave range in gas-and-droplet medium is considered. The horizontal pipeline appears semi-pointed, the solution is sought in the form of a harmonic wave. Wave is one-dimensional, having small amplitude of oscillations. Based on dispersion equations, dependence of phase velocity and attenuation coefficient on frequency of acoustic wave disturbance and on volume content of suspended phase (water droplets) are built. In the high frequency region, the attenuation coefficient increases with the volume content. The formulas for reflection and passage coefficients are derived taking into account pipeline narrowing due to hydrate deposits. The results of numerical calculations illustrating the dynamics of pulse signals depending on the thickness of the gas hydrate on the inner wall of the pipeline are presented. Calculations are based on forward and backward Fourier transformations and the use of software. It is established that the greater the hydrate deposit on the wall in thickness, the greater the amplitude of the returned reflected signal.","PeriodicalId":309215,"journal":{"name":"Multiphase Systems","volume":"27 1","pages":"0"},"PeriodicalIF":0.0,"publicationDate":"1900-01-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"125401772","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}

{"title":"Non-stationary process characteristics of the gas outflow into a liquid","authors":"M. Alekseev, I. Vozhakov, S. Lezhnin","doi":"10.21662/mfs2019.2.012","DOIUrl":"https://doi.org/10.21662/mfs2019.2.012","url":null,"abstract":"A numerical simulation of the process of the outflow of gas under pressure into a closed container partially filled with liquid was carried out. For comparative theoretical analysis, an asymptotic model was used with assumptions about the adiabaticity of the gas outflow process and the ideality of the liquid during the oscillatory one-dimensional motion of the liquid column. In this case, the motion of the liquid column and the evolution of pressure in the gas are determined by the equation of dynamics and the balance of enthalpy. Numerical simulation was performed in the OpenFOAM package using the fluid volume method (VOF method) and the standard k-e turbulence model. The evolution of the fields of volumetric gas content, velocity, and pressure during the flow of gas from the high-pressure chamber into a closed channel filled with liquid in the presence of a ”gas blanket“ at the upper end of the channel is obtained. It was shown that the dynamics of pulsations in the gas cavity that occurs when the gas flows into the closed region substantially depends on the physical properties of the liquid in the volume, especially the density. Numerical modeling showed that the injection of gas into water occurs in the form of a jet outflow of gas, and for the outflow into liquid lead, a gas slug is formed at the bottom of the channel. Satisfactory agreement was obtained between the numerical calculation and the calculation according to the asymptotic model for pressure pulsations in a gas projectile in liquid lead. For water, the results of calculations using the asymptotic model give a significant difference from the results of numerical calculations. In all cases, the velocity of the medium obtained by numerical simulation and when using the asymptotic model differ by an order of magnitude or more.","PeriodicalId":309215,"journal":{"name":"Multiphase Systems","volume":"13 1","pages":"0"},"PeriodicalIF":0.0,"publicationDate":"1900-01-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"131063392","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}

{"title":"Numerical analysis of acoustic scattering from a layer of droplets under external action","authors":"E. Nasibullaeva","doi":"10.21662/mfs2022.3.015","DOIUrl":"https://doi.org/10.21662/mfs2022.3.015","url":null,"abstract":"The study of acoustic scattering from small obstacles is important both for studying the fundamental nature of this phenomenon and from a practical point of view, since many applications of acoustic waves are based on the scattering phenomenon. Within the framework of the problem of acoustic scattering from a set of sound-permeable spheres arbitrarily located in space, under external influence, scattering from a layer of drops is studied. The main goal is to determine the parameters at which the system is sensitive to changes in the droplet radius. A special case of a small spheres layer is possible when a region containing many small inhomogeneities is conditionally two-dimensional one (one of the three dimensions can be neglected). The problem is solved numerically using a generalized calculation technique based on the fast multipole method, which allows achieving high accuracy of the results obtained with minimal CPU time. A series of computational experiments was carried out for various ratios of the physical parameters of the drop and the environment (density and sound speed) for a different number of spheres and the density of their arrangement in the configuration. It is shown that the system is most sensitive to changes in the droplet radius in the case when the elasticity of the substance inside the droplet is less than that of the external environment, and with an increase in the sphere number in dense configurations the system is most sensitive when the elasticity of the substance inside the droplet is much greater than that of the external environment. It is found that the sensitivity to changes in the initial data decreases with an increase in the distance between the sphere centers, that is, with a decrease in the density of the arrangement of the spheres in the configuration.","PeriodicalId":309215,"journal":{"name":"Multiphase Systems","volume":"111 1","pages":"0"},"PeriodicalIF":0.0,"publicationDate":"1900-01-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"116232159","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}