Multiphase Systems最新文献

{"title":"Mathematical modeling of the process of decomposition of gas hydrate formation without the influence of various external sources","authors":"V. E. Yuziev, A. Rusinov","doi":"10.21662/MFS2019.1.009","DOIUrl":"https://doi.org/10.21662/MFS2019.1.009","url":null,"abstract":"The paper considers a homogeneous reservoir in the form of a pancake with characteristic linear dimensions corresponding to real deposits: with a radius of the order of several kilometers, and a height of tens of meters. Since the radii of such layers are much larger than their thickness, this allows one to take into account the thermal interactions of the field with the surrounding rocks through the upper and lower boundaries of the layer in a flat one-dimensional approximation. To describe the model, such basic equations were used as the law of conservation of mass of gas and water in the reservoir, the equation of heat balance and temperature fields near the reservoir boundary, as well as initial and boundary conditions. The constructed theoretical model makes it possible to analyze the possibility of realizing the complete gas recovery of the layers only due to the thermal reserve of the hydration layers themselves, as well as the surrounding mountain massif. For the values of the parameters that determine the initial state of the board, numerical experiments were performed. The dynamics of reservoir pressure and hydrate saturation in the reservoir are presented. As a result of the research, it was established that at a constant gas extraction rate, the achievement of reservoir pressure up to 2.6 MPa and, accordingly, a temperature of 273 K occurred in about 5 years. It is shown that when gas is taken from a reservoir with a radius of 3000 m and a thickness of 50 m, its hydrate saturation decreases by about 38% over 5 years.","PeriodicalId":309215,"journal":{"name":"Multiphase Systems","volume":"77 1","pages":"0"},"PeriodicalIF":0.0,"publicationDate":"2019-03-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"114014656","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":"Flexural vibrations of the pipeline on elastic supports with moving fluid","authors":"A. G. Khakimov, A. A. Yulmukhametov","doi":"10.21662/MFS2019.1.002","DOIUrl":"https://doi.org/10.21662/MFS2019.1.002","url":null,"abstract":"In the work investigated the flexural vibrations of the pipeline. Parts of the pipeline on both sides of the sagging section have elastic supports. It is assumed that a constant longitudinal force acts along the neutral line. An incompressible fluid flows through the pipe at a constant average speed. The influence of internal pressure in the pipe on these oscillations is taken into account. The direct problem of determining the eigenfrequencies of flexural vibrations of the pipeline by the Kirchhoff model using Ferrari formulas is solved. The frequency spectrum is determined depending on the fluid pressure, the elasticity of the supports, the velocity of the fluid through the pipe. Particular and limiting cases are considered, for example, when the stiffness of the supports is very large and when they are very small. Graphs of the dependence of the first and second eigenfrequencies on the velocity of the transported liquid at different values of the liquid density parameter are constructed. It is shown that with the growth of the velocity parameter there is a decrease in the natural frequencies of flexural vibrations of the pipeline, and the faster the higher the density parameter of the liquid. It is determined that with an increase in the mass of the liquid per unit length of the pipeline there is a decrease in the natural frequencies of bending vibrations of the pipe. It is found that with the increase in the mass flow through the pipe, the natural frequencies of bending oscillations also decrease. It is confirmed that the frequencies of flexural vibrations of the pipeline are the same for the cases of pipe fastening “rigid fixing — rigid fixing” and “free end — free end”. The results of the study will contribute to the development of methods of acoustic diagnostics and non-destructive testing and can find technical application for monitoring and diagnostics of pipeline systems.","PeriodicalId":309215,"journal":{"name":"Multiphase Systems","volume":"26 1","pages":"0"},"PeriodicalIF":0.0,"publicationDate":"2019-03-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"116071486","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":"Influence of viscosity temperature dependence on the spectral characteristics of the thermoviscous liquids flow stability equation","authors":"A. Nizamova, V. Kireev, S. Urmancheev","doi":"10.21662/MFS2019.1.007","DOIUrl":"https://doi.org/10.21662/MFS2019.1.007","url":null,"abstract":"The flow of a viscous model fluid in a flat channel with a non-uniform temperature field is considered. The problem of the stability of a thermoviscous fluid is solved on the basis of the derived generalized Orr-Sommerfeld equation by the spectral decomposition method in Chebyshev polynomials. The effect of taking into account the linear and exponential dependences of the fluid viscosity on temperature on the spectral characteristics of the hydrodynamic stability equation for an incompressible fluid in a flat channel with given different wall temperatures is investigated. Analytically obtained profiles of the flow rate of a thermovisible fluid. The spectral pictures of the eigenvalues of the generalized Orr-Sommerfeld equation are constructed. It is shown that the structure of the spectra largely depends on the properties of the liquid, which are determined by the viscosity functional dependence index. It has been established that for small values of the thermoviscosity parameter the spectrum compares the spectrum for isothermal fluid flow, however, as it increases, the number of eigenvalues and their density increase, that is, there are more points at which the problem has a nontrivial solution. The stability of the flow of a thermoviscous fluid depends on the presence of an eigenvalue with a positive imaginary part among the entire set of eigenvalues found with fixed Reynolds number and wavenumber parameters. It is shown that with a fixed Reynolds number and a wave number with an increase in the thermoviscosity parameter, the flow becomes unstable. The spectral characteristics determine the structure of the eigenfunctions and the critical parameters of the flow of a thermally viscous fluid. The eigenfunctions constructed in the subsequent works show the behavior of transverse-velocity perturbations, their possible growth or decay over time.","PeriodicalId":309215,"journal":{"name":"Multiphase Systems","volume":"77 1","pages":"0"},"PeriodicalIF":0.0,"publicationDate":"2019-03-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"127301338","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":"Review of studies on the computational diagnosis of local defects of structural elements","authors":"A. G. Khakimov","doi":"10.21662/mfs2019.1.001","DOIUrl":"https://doi.org/10.21662/mfs2019.1.001","url":null,"abstract":"Rods, beams, shafts, pipelines, round plates. membranes are parts of structures in which local defects such as cracks, dents, cavities, local corrosion can be formed. Provides an overview of the research A. G. Khakimov for the diagnosis of local defects. It is received: 1. The two eigenfrequencies of the longitudinal oscillations can determine the location and the notch parameter characterizing its size. 2. The three lower eigenfrequencies of the longitudinal oscillations can determine the initial coordinate and the value of the attached distributed mass to the stepped rod, as well as the ratio of the areas. 3. The solution of the inverse problem for extended rods allows us to determine the coordinate of the incision and the parameter containing its depth and length, according to the incident and reflected waves at the observation site. 4. The reflection from the air cavity and the passage of a longitudinal damped traveling wave in a pipeline immersed in a viscous liquid are determined, and the solution of the inverse problem allows to determine the coordinate of the air cavity and its length according to the reflected wave at the observation site. 5. The initial coordinate and the length of the longitudinal through radial section of the hollow shaft are determined by the two eigenfrequencies of torsional vibrations. 6. The coordinate, length and parameter of the drill string notch are determined by the three eigenfrequencies of the torsional vibrations. 7. The reflection from the distributed mass attached to the pipeline and the passage of the flexural traveling wave are considered. The dependence of the solution on the initial coordinate of the distributed mass and its magnitude is obtained, and the inverse problem of determining the initial coordinate of the distributed mass and its magnitude from the data of the reflected wave at the observation point is solved. 8. The radius and thickness of the thin central region of the membrane are determined by the two eigenfrequencies of the transverse vibrations. 9. The radius, thickness of the thinned central area of the plate and the value of the attached distributed mass are determined by the three natural frequencies of the bending oscillations. 10. By three frequencies of bending vibrations it is possible to determine the velocity parameter, the relative mass of the product per unit length of the pipeline and the relative mass of sediments on the walls of the pipeline and, as a consequence, the mass flow of liquid through the pipeline.","PeriodicalId":309215,"journal":{"name":"Multiphase Systems","volume":"51 1","pages":"0"},"PeriodicalIF":0.0,"publicationDate":"2019-03-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"129000602","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 influence of the vortex tube channel length on the separation of air by its temperature","authors":"B. R. Adiullin, C. Mikhaylenko","doi":"10.21662/MFS2019.1.005","DOIUrl":"https://doi.org/10.21662/MFS2019.1.005","url":null,"abstract":"Based on the prepared counterflow vortex tube model with four inlets, the effect of the length of the vortex tube channel on the generation of cold and hot air is investigated. In the simulation were used standard equations of gas dynamics, which include the equations of continuity, conservation of momentum, total energy, and the state of an ideal gas. To consider turbulent effects was chosen a -varepsilon$ turbulence model. Computational experiments were carried out in the OpenFOAM software using the sonicFoam solver. The prepared grid allowed modeling vortex tubes with the main channel length varying from 20 to 70 cm. All calculations were carried out under the same boundary conditions with constant pressure at the inlets and atmospheric pressure at the hot and cold outlets. The constructed model adequately reproduces the two-vortex structure of the air flow in the vortex tube. To obtain and process the results were used OpenFOAM utilities and a script implementing the algorithm for averaging the values at the tube outlets written in Python. The results were obtained on the temperatures and mass flow rates of air in cold and hot outlets of the vortex tube depending on the length of the device. According to the analysis of the obtained data, it was shown that increasing the length of the channel of the vortex tube significantly increases the production of cold air with a certain increase in its temperature. An increase in the temperature of the produced hot air with an increase in the length of the vortex tube was also noted.","PeriodicalId":309215,"journal":{"name":"Multiphase Systems","volume":"23 1","pages":"0"},"PeriodicalIF":0.0,"publicationDate":"2019-03-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"129586424","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":"Melting of ice in a porous medium saturated with ice and gas while injecting warm water","authors":"V. Shagapov, M. N. Zapivakhina","doi":"10.21662/MFS2018.4.016","DOIUrl":"https://doi.org/10.21662/MFS2018.4.016","url":null,"abstract":"The numerical models for the injection of warm water (in the temperature range from 300 to 340 K) into a cold porous formation are considered. Simplified models describing the processes of heat and mass transfer are proposed. The influence of the parameters determining the initial state of the porous medium, the boundary pressure, temperature and moisture content on the rate of propagation of hydrodynamic and temperature fields in the porous medium is investigated. It has been established that it is economically feasible to melt frozen soils saturated with ice and gas (air) at a sufficiently low temperature of the injected water (about 300 K).","PeriodicalId":309215,"journal":{"name":"Multiphase Systems","volume":"61 1","pages":"0"},"PeriodicalIF":0.0,"publicationDate":"2019-01-11","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"132236279","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 model of the servo piston of the fuel metering unit using matrix approach and neural network","authors":"E. Denisova, M. Chernikova","doi":"10.21662/MFS2018.4.015","DOIUrl":"https://doi.org/10.21662/MFS2018.4.015","url":null,"abstract":"In the paper, the model of a servo piston of a fuel metering unit based on a matrix approach using neural networks is considered. To develop the model of a servo piston, the dependence of the initial piston deviation on the control signal for different values of the nozzles is used. This dependence is represented in the form of a matrix and is used in the neural network. This approach allows describing the movement of the servo piston with a sufficient degree of accuracy. As a record of change squares adjustment of the nozzles is a source of parametric uncertainty in the operation of the automatic control system can lead to a drop in the quality of control, such accounting is relevant. The model of the servo piston is proposed to be used in the structure of the automatic control system for a gas turbine engine and for semi-natural stands.","PeriodicalId":309215,"journal":{"name":"Multiphase Systems","volume":"32 1","pages":"0"},"PeriodicalIF":0.0,"publicationDate":"2018-12-28","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"127930782","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 simulation of single vapor bubble dynamics in a liquid in an intense acoustic field","authors":"A. Davletshin, T. F. Khalitova","doi":"10.21662/mfs2018.4.018","DOIUrl":"https://doi.org/10.21662/mfs2018.4.018","url":null,"abstract":"The possibility of increasing the calculation efficiency by the joint use of two models of the dynamics of a single weakly-nonspherical vapor bubble under its strong collapse in liquid is studied. In both models the motion of liquid and vapor is split into a spherical component and its small nonspherical perturbation. The models differ in the description of the spherical component. In the first (simplified) model, it is described by a system of ODE together with partial differential equations in temperature, derived under the assumption of weak compressibility of liquid and bubble homobaricity. In the second model, one-dimensional gas dynamics equations are applied. The advantage of the simplified model consists in determining a numerical solution with much-less computer time costs in comparison with what is required for the numerical integration of gas dynamics equations. The assumptions used in the simplified model in the final stage of collapse become incorrect, and, as a result, the numerical solution errors increase. Therefore, the simplified model is applied at the beginning of bubble collapse, whereas the gas dynamics equations are used at its end. Within this approach, the numerical solution in the final stage of collapse is dependent on the moment of transition to the gas dynamics equations. It is shown that satisfactory description of evolution of bubble sphericity distortion is achieved when the transition is made under the condition that the Mach number M of vapor in the vicinity of the bubble surface is less than 0.4. Satisfactory resolution of the shock wave in the bubble is attained when the transition is performed at M<0.2.","PeriodicalId":309215,"journal":{"name":"Multiphase Systems","volume":"1 1","pages":"0"},"PeriodicalIF":0.0,"publicationDate":"2018-12-24","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"121264878","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":"Study of the effect of dynamic blocking of emulsions containing solid inclusions","authors":"A. Rakhimov, A. Akhmetov, A. A. Valiev, R. R. Asadullin","doi":"10.21662/MFS2018.4.017","DOIUrl":"https://doi.org/10.21662/MFS2018.4.017","url":null,"abstract":"The paper presents the results of experimental studies of the flow of stabilized water-oil emulsions prepared from oil and formation water from the wells of the West Kochevne field, as well as with the presence of chrysotile and aerosil in cylindrical and flat capillaries (in the crack patterns). The effect of dynamic blocking has been discovered, which consists in the fact that in sections of capillaries and in a model of cracks, with a constant pressure drop, the flow of reverse oil-water emulsions stops with time. An increase in the content of isotropic and anisotropic particles led to an increase in the viscosity of the emulsion and a decrease in the time of onset of dynamic blocking. With the same percentage of particles in emulsions containing chrysotile, the time of onset of blocking and the volume of leaked emulsion before blocking is an order of magnitude less than that of emulsions containing aerosil. However, in this case, the viscosity of the emulsion with aerosil is even higher than that of a similar emulsion with chrysotile.","PeriodicalId":309215,"journal":{"name":"Multiphase Systems","volume":"5 1","pages":"0"},"PeriodicalIF":0.0,"publicationDate":"2018-12-21","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"134608767","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 local inhomogeneity of the medium from the natural frequencies of string oscillations","authors":"I. Utyashev, A. M. Akhtyamov","doi":"10.21662/MFS2018.4.014","DOIUrl":"https://doi.org/10.21662/MFS2018.4.014","url":null,"abstract":"The paper considers the problem of determining the local inhomogeneity of the medium from the natural frequencies of string oscillation. The inhomogeneity is modeled in three sections: in the first and third sections medium is homogeneous, and on average section the elastic characteristics are modeled by a quadratic function. This model is implemented using the conjugation conditions at boundary between media. It is shown that to identify the center of an inhomogeneity and determine its size, two natural frequencies are enough, and in the case of rigid fixing of both ends of the string, the solution of the problem is dual. The problem is solved by expanding the fundamental system of solutions into a power series in the variables x and λ. The estimates of the error of the method are given.","PeriodicalId":309215,"journal":{"name":"Multiphase Systems","volume":"1 1","pages":"0"},"PeriodicalIF":0.0,"publicationDate":"2018-12-19","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"130063321","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}