Dimensionless Complexes Research Articles

Formation of submicron conical morphology of the surface of nanometer-thick films of the Al–Fe alloy under various conditions of ion-assisted deposition on glass

The morphology, topography and wetting with distilled water of Al–1.5 at. % Fe alloy films with a thickness 25–90 nm, formed on glass by ion-assisted deposition using a resonance ion source of vacuum electric arc plasma, have been studied. Using scanning probe microscopy, it is shown that, depending on the mode and the time of deposition, the modification of films is accompanied by changes in longitudinal and transverse roughness parameters, as well as parameters – dimensionless complexes, the measurement of which makes it possible to quantitatively describe the processes of coning in the Al–Fe alloy/glass system. Thus, the arithmetic mean roughness of the films increases with deposition time in the range 20–40 nm. Under self-irradiation conditions, a transition from island-like film growth to layer-by-layer film growth was detected. The influence of the substrate topography on the longitudinal step parameters of the film topography has been established. The size and surface density of the microdroplet fraction particles are studied by scanning electron microscopy. The frequency distributions of the microdroplet fraction by size are satisfactorily approximated by the lognormal distribution. It is found that in the mode of irradiation with intrinsic ions, 60–70% of the microparticles have a size of up to 0.8 μm. For the first time, a double Gaussian function was used to approximate the distribution histograms of local maxima and minima of the film relief, which made it possible to increase the accuracy of the description compared to the normal law. The effectiveness of this approach in analyzing the structure formation of nanometer films at various stages of growth has been demonstrated. Using the bi-Gaussian surface model, the role of topographic characteristics in controlling the wetting of modified coatings is revealed. The mechanism of heterogeneous wetting of hydrophilic films in the Cassie mode with contact angles ranging 50°–80° is discussed. It is found that in the potential mode, with an increase in the deposition duration to 10 h, the distribution of the film relief is close to the normal law, and the formation of a developed submicron conical morphology on the surface leads to blended wetting.

DESIGN OF HIGHLY EFFICIENT WATER PASSAGE OF PUMP-TURBINE

The problem of the need to develop renewable energy sources as a way to save the energy supply and energy independence of Ukraine by changing the consumption of carbohydrates is considered. It is shown that the development of Ukrainian renewable energy must occur in parallel with the development of energy storage systems and balancing of the energy system. The most effective system for storing energy and balancing the energy system is pumped storage power stations (PSPS). The work shows that the design of a highly effective equipment of a hydroelectric power plant depends on the correct selection of the element geometry of the pump-turbine water passage. Therefore, it is possible to ensure the necessary level of energy characteristics of hydraulic equipment. A method of dimensionless average parameters was established, which allows even at the initial stages of designing new reversible hydraulic machines to determine the optimal geometry of the watter passage elements. This method showed good results during the numerical research of Francis hydraulic turbines at a wide range of heads, as well as reversible hydromachines at heads of 300–500 m. Using expressions that establish the connection of hydrodynamic characteristics with dimensionless complexes, three variants of the flow part of the high-pressure pump-turbines (ORO500) were investigated. Based on the obtained results, a significant influence of the geometry on the hydraulic indicators of the machine was noted. The distribution of energy losses in the inlet, blade system and outlet was analyzed. The greatest energy losses occur in the inlet of the pump-turbines. To increase the energy and kinematic indicators of the ORO500 pump-turbines, the geometry of the feed elements, as well as the spiral casing and stator, was changed. Variants for improving the parameters in the elements of the supply of the water passage of the pump-turbine are proposed.

Критериальная база рабочего процесса трубы Гартмана–Шпренгера

The issue of creating a criteria base for the Hartmann–Sprenger pipe workflow based on a closed mathematical model is considered. On the basis of a closed mathematical model, the main parameters affecting the increase in the total temperature of the gas at the end of the dead-end cavity above the deceleration temperature of the incoming flow are recorded. Parameters with the same dimension are combined into one group so that only one dimensionless complex is obtained for all these quantities. Finding dimensionless complexes based on the modeling theory allowed us to determine the criteria base of the Hartmann–Sprenger pipe workflow.

Simulation of reaction initiation in powder compacting from the surface with composite formation in equivalent reaction cell

In the present work, we propose a new variant of the model of the composite synthesis under surface heating. We believe that the formation of the composition occurs at the level of reaction cell. The diffusion-controlled process of reduction of one material by another from an oxide is described in the framework of the problem with moving boundaries. It is assumed that the formation of the matrix composition is carried out by the diffusion mechanism. From the position of interfaces, we find the relative volume fractions of oxide phases and the fraction of volume occupied by the matrix. The averaging method of the analysis results at the reaction cell level makes it possible to use these data at the macroscopic level. Volume fractions of phases and average matrix composition (obtained by averaging over the area occupied by the matrix) provide values reflecting the composition of the composite at the macro level. The problem is solved numerically in dimensionless formulation. Dimensionless complexes of physical quantities are distinguished. The estimation of these parameters is performed. The conditions of correctness of the proposed approach are established from comparison of temporal and spatial scales of thermal and diffusion phenomena. A numerical algorithm for the joint solution of macro- and mesolevel problems has been developed. The proposed algorithm makes possible the investigation of the dynamics of composition changes at all points. The model is supplemented by the calculation of stresses and strains from the data on composition and temperature changes in reaction cells. Averaged values of stresses are transferred to macro level.

Model of Influence of the Machined Material Properties on Wear of the Polymeric-Abrasive Tool Filaments

Abstract For polymer-abrasive brush tools (PABT) working on CNC machines it is necessary to correct their wear constantly, since it is much higher compared to the wear of metal tools. Based on the dependence of tool wear on machining parameters for various materials, it is necessary to study the influence of the physical and mechanical properties of the material machined. The purpose of the paper is to study the process of finishing the surfaces of parts made of materials of different types with PABT. The analysis of dimensional wear of disc PABTs during the polishing various materials with certain physical and mechanical properties is provided in the article. The polishing was carried out in rational modes that ensure high quality and productivity of surface treatment. The similarity theory and dimensional analysis were used to assess the influence of the properties of the material machined on the intensity of PABT filament wear. To calculate it, dimensionless complexes were established, which take into account the physical and mechanical properties of the machined materials and evaluate their resistance to the penetration of abrasive grains, the ability of the material to absorb mechanical energy in the process of deformation and destruction under the impact of PABT filaments. The developed model was created for the first time. It made it possible to solve the problem of predicting the degree of dimensional wear of the disc PABT when polishing various materials, including difficult-to-machine ones. Prediction of the intensity of PABT filaments wear allows timely correction of the tool position during machining on CNC machines to ensure a constant pressing of the PABT to the surface being machined. The obtained Км material coefficient takes into account the influence of the physical and mechanical properties of the machined material and then estimates the intensity of PABT filaments wear. The KМ material coefficient can also be used to assess the PABT life and calculate the economic efficiency of the parts finishing treatment at the stage of technology development and the selection of polishing tools.

Об эффективности легкосбрасываемых конструкций, расположенных в покрытии

The dynamics of the development of an internal explosion is studied considering the action of blast relief panels. The time spent on the exit of the blast relief panel from the opening, as well as the effect of gravity, are considered. The processes are investigated from the moment the blast relief panel leaves the opening and until it is fully opened. A model is formed considering the initial speed of the blast relief panel at the exit from the opening. The model is limited to considering the pressures, at which it is assumed that the degree of expansion of gases during combustion is unchanged, and to determine the rate of gas outflow, the Bernoulli equation for an incompressible liquid is applicable. Dimensionless complexes and parameters characterizing the process under study are established. As a final result, the dependence of the maximum pressure during the opening-up of the opening (the first peak) from the dimensionless complex based on the initial data is proposed. Among them are the characteristics of the blast relief panel, the combustion rate, the geometric shape, and dimensions of the opening. It is concluded that the maximum possible pressure at the first peak does not directly depend on the area of the opening. The rate of pressure relief at the moment of opening-up of the opening is determined by the area of the side space calculated as the product of the perimeter of the opening to the amount of displacement of the blast relief panel. A method is proposed for reducing pressure at the first peak by increasing the number of openings while maintaining the total area for pressure relief, which depends on the bearing capacity of panels. The results obtained allow to establish under what conditions the pressure at the first peak exceeds the pressure at the second one. Thanks to this, it is possible to adjust the explosion resistance of an object by changing the design of a blast relief panel, or by strengthening the load-bearing elements.

Гідродинамічне дослідження групи струменів рідини в апаратах із циліндричними розподільними пристроями

The analysis of existing studies regarding the process of steam condensation from a vapor-gas mixture on liquid jets allows us to conclude that the vast majority of them are experimental in nature, so the results of these studies can be correctly used only for the appropriate range of parameter changes of the liquid and gaseous phases. Also, the subject of research in them is mainly the hydrodynamic mode of a continuous liquid jet along its entire length. During theoretical and experimental studies, it was established that the shape of the jets flowing out of the cylindrical holes counter to the oncoming steam current differs from cylindrical shape, depends on the flow parameters, and is characterized by their rotation with intense wave formation on the jet surfaces. The jets are combined with each other with their subsequent disintegration along the current, dispersed and carried away with the steam current. Accordingly, it is incorrect to apply existing methods of heat transfer calculation to the analysis of heat transfer in this type of jets, only on solid jets of liquid, outside the investigated range of parameters. That is, using classical equations is impossible due to the complexity of calculating the cross-sectional area of jet groups flowing through cylindrical holes, and accordingly, the area of the heat exchange surface. Namely, it is impossible to use the traditional concept of the heat transfer coefficient as a parameter. Therefore, most of the existing calculation methods are based on using dimensionless complexes that describe the degree of change in the temperature of the liquid along the length of the jets under the appropriate geometric conditions. That is, without finding the limits of changes in the continuity of liquid jets, determining the limiting hydrodynamic modes using the existing methods of heat exchange calculation is incorrect.

СТОХАСТИЧЕСКАЯ МОДЕЛЬ ПРЕДВАРИТЕЛЬНОЙ ОЧИСТКИ ДИЗЕЛЬНЫХ ТОПЛИВ В МНОГОКАНАЛЬНОМ ГИДРОДИНАМИЧЕСКОМ ФИЛЬТРЕ

Modern needs of technologies, machinery and equipment of the agro-industrial complex make it necessary to solve the issues of cleaning diesel fuels from mechanical impurities. However, the existing designs of standard filters containing replaceable filter elements have a small resource and do not always meet the requirements of efficient fuel purification, as a result of which the possibility of sudden failures of mechanization means is not excluded. In order to evaluate the effectiveness of the use of a multichannel hydrodynamic filter of the original design, theoretical studies of the process of preliminary purification of diesel fuel by this device from solid polydisperse particles of pollution have been carried out. As a result of the research, for the first time, the possibility of using a stochastic approach to describe the process of pre-purification of fuel in a hydrodynamic filter with conical filter elements in various operating modes has been confirmed. A stochastic model of the process under study has been developed. It is theoretically shown that the preliminary purification of fuel in a multichannel hydrodynamic filter with conical filter elements can be described using stationary solutions of the Foker- Planck-Kolmogorov equation. The main parameters and dimensionless complexes, taking into account the features of the description of the process of preliminary hydrodynamic fuel cleaning in conical filter elements, taking into account the influence of random components, are found.

Roughness coefficient of the Instruch riverbed

The article presents the results of improving the numerical method developed in [1-3] for calculating the roughness coefficient of the riverbed (RCOTR) to increase stability and using it to study the dependence of the RCOTR of the Instruch River on dimensionless complexes in different seasons.

MODES OF ADHESIVE BONDING LAYER FORMATION DURING ROLL MOTION IN THE PROCESS OF SHEET LAMINATION

Novel technologies for the synthesis and processing of materials and products based on these materials, such as additive manufacturing, require the use of mathematical modeling to study the accompanying physical and chemical phenomena. These technologies include sheet lamination, which today has a variety of applications and numerous modifications. This article presents a model of adhesion layer formation in the creation of multilayer composites, which is controlled by a hot roller moving along the surface of the top layer. The dynamics of reagent heating depends on the thermal properties and sizes of all layers, the temperature of the roller, and its pressure against the surface, with characteristic times and spatial scales for different processes. The transition to dimensionless variables allowed the identification of dimensionless complexes to determine different modes of development of the adhesion layer synthesis process. Based on the combustion theory and non-equilibrium thermodynamics, new criteria of the process initiation and transition to a quasi-stationary mode were elaborated. The behavior of various thermodynamic quantities was analyzed in detail, including heat storage in the heated layer, enthalpy excess, and entropy production. The reaction zone is wide in most cases. The dependences of the half-conversion time on the model parameters are plotted for a finite layer size. This is a new characteristic for sheet lamination technology. A controlled mode, a fast bulk synthesis mode, a slow transformation mode maintained by the heat stored in the inert materials, and a quasi-stationary mode are identified. Criteria were established for different modes of reactions under conjugate heat exchange conditions.

Calculation of the roughness of the Sheshupe riverbed according to hydrological yearbooks

When conducting engineering hydrometeorological surveys, hydrological and hydraulic calculations are performed, in which an indicator characterizing the resistance of the channel to flow is taken into account. The integral characteristic of the hydraulic resistance of river channels is the roughness coefficient. In accordance with regulatory documents, the values of the roughness of the channel of the water body and the floodplain are taken according to the qualitative characteristics of the channel, which is subjective and can lead to significant errors in the calculations. The use in calculations of the roughness coefficient obtained as a result of single field measurements is inappropriate, since it can change throughout the year. This paper presents the results of studying the roughness of the Sheshupe river bed in different seasons of the year, and establishes the dependence of the roughness coefficient on dimensionless complexes (Froude and Reynolds numbers). The published data of measurements on the Sheshupe River (hydrological post in the village of Dolgoe) were used for the calculations.

Начальная стадия взрыва при легкосбрасываемой конструкции панели, расположенной в покрытии здания

The initial phase of a gas deflagration explosion is considered, taking into account the action of blast relief panel structures in the roof of the building, which provide overpressure relief to protect the building structures from the explosion and maintain their integrity. This, in turn, ensures the protection of people in the building from the collapse of the building itself. The structure is a lightweight panel. It closes the opening in the roof and is buried in it to its thickness. The panel comes into motion under pressure. The movement begins after the pressure force overcomes the resistance, which is composed of the weight of the structure and the bond force of the structure with the roof frame. After the blast relief structure is shifted to the depth of sealing, the space for depressurizing is opened. The dynamics of the panel movement and pressure change are studied before the start of pressure relief through the opening space along the perimeter of the opening. By the time the panel exits the opening, the explosion pressure may reach values incompatible with the stability of the bearing structures. The paper presents dimensionless complexes that determine the explosion process at this stage. The maximum pressure at this stage of the explosion is determined by the mass per unit area of the blast relief panel, the bursting pressure of the connections of the blast relief panel with the frame, and the ratio of the opening time of the opening to the time of the start of movement of the blast relief panel. The relation of these times depends on the dimensionless complexes defined in the work. An unacceptable increase in pressure at the considered stage of the explosion can occur at any opening area. In general, the process is determined by the properties of the panel, the volume of the room, the speed of combustion and the nature of the panel attachment.

Математичне моделювання теплопередачі у повітряно-крапельному потоку камери підшипника ГТД

The gas-liquid flow in the bearing chamber (BC) of the gas turbine engine is realized due to the interaction of the sealing air and oil supplied for lubrication and cooling of friction units. The complex nature of the flow movement is determined not only by the BC geometry but also by the presence of rotating elements and the manner of oil supply and flow removal. The most important result for the engineering practice of BC flow modelling is the determination of the heat transfer coefficient to the inner wall. The variety of influencing factors causes difficulties even at the stage of an integral mathematical model of the process formation, which makes it possible to determine this coefficient. As a result, significantly different approaches are used – from three-dimensional CFD modelling of a heterogeneous flow up to the use of a criterion equation that formally considers the effect of geometric and regime parameters on a heat transfer. The first approach requires significant computational resources, and certain difficulties arise in setting the initial and boundary conditions, especially in terms of droplet parameters. Homogeneous models somewhat simplify the problem, including when formulating the boundary conditions. However, all the effects of the influence of the droplet diameter are levelled. In both cases, the computation time is long, and the results of CFD simulations require selective experimental verification. Therefore, it is problematic to use this approach solely for engineering problems, as well as when generalizing experimental data in several regime parameters. When using the criterion equation, the calculation procedures are as simple as possible. However, dimensionless complexes do not ensue from the basic equations of heterogeneous media mechanics and do not consider the effects of interfacial interaction during heat transfer in the BC. Therefore, the possibility of the application of the proposed correlations for other BC geometries and oil and air supplying conditions also needs to be experimentally confirmed. This makes it problematic to use such correlations at the design stage of the BC and the oil system as a whole. The preferred approach for engineering practice is when the thermohydraulic processes in the BC are described on the basis of the proven equations of heterogeneous media mechanics with the transition to a two-dimensional problem by averaging the phase parameters along the axis. This averaging is justified by the fact that the main heat carrier from the core to the inner wall of the BC is the radial flow of droplets. In view of the low volume fraction of droplets, the Lagrange approach is used to simulate a two-phase flow in the BC core. The droplet parameters along the trajectory are calculated considering the interfacial interaction with the air. In this regard, the air velocity field is determined by considering the geometry of the BC, the flow through the seals and the shaft speed. Here, it is possible to consider not only the droplet polydispersity but also the effects of primary droplet reflection, the formation, and movement of secondary droplets during the formation of a near-wall oil film, the thermal resistance of which directly affects the value of the internal heat transfer coefficient.

RESULTS OF THE STUDY OF A TURBOGENERATOR WITH A PERIPHERAL-SIDE CHANNEL IN NON-DIMENSIONAL AND CRITERIAL COMPLEXES

Dimensionless and criterial complexes are successfully used in many technical fields. They play an important role in research and design. There are a large number of dimensionless and criterial complexes, which have their advantages and are chosen depending on the topic and specific objectives of the study. The article considers dimensionless and criterial complexes most often used in studies of turbomachines, in particular vortex expansion machines - relative internal (isoentropic) efficiency, degree of pressure drop, adjusted wheel speed, speed coefficient, adjusted diameter, flow factor and coefficient. The authors processed the data of the experimental study of the turbogenerator with a peripheral-side channel and presented them in the form of graphical dependences using these complexes. The improvement of these energy-saving turbogenerators is important because they are used to generate electricity from excess gas pressure, are considered environmentally friendly and are needed for the development of distributed energy. Vortex expansion machines with a peripheral-lateral channel are also poorly understood, so the topic is relevant. In this study, their area of use was determined and reflected in the ns - Ds diagram among radial and other vortex expansion turbomachines to facilitate their comparison and design.

Modeling of Flow Heat Transfer Processes and Aerodynamics in the Cabins of Vehicles

Ensuring comfortable climatic conditions for operators in the cabin of technological machines is an important scientific and technical task affecting operator health. This article implements numerical and analytical modeling of the thermal state of the vehicle cabin, considering external airflow and internal ventilation. A method for calculating the heat transfer coefficients of a multilayer cabin wall for internal and external air under conditions of forced convective heat exchange is proposed. The cabin is located in the external aerodynamic flow to consider the speed and direction of the wind, as well as the speed of traffic. Inside the cabin, the operation of the climate system is modeled as an incoming flow of a given temperature and flow rate. The fields of velocities, pressures, and temperatures are calculated by the method of computer hydrodynamics for the averaged Navier–Stokes equations and the energy equation using the turbulence model. To verify the model, the values of the obtained heat transfer coefficients were compared with three applied theories obtained from experimental data based on dimensionless complexes for averaged velocities and calculated by a numerical method. It is shown that the use of numerical simulation considering the external air domain makes it possible to obtain more accurate results from 5% to 75% compared to applied theories, particularly in areas with large velocity gradients. This method makes it possible to get more accurate values of the heat transfer coefficients than for averaged velocities.

Analiz izmeneniya koeffitsienta sherokhovatosti rusla maloi reki v zadannom stvore (na primere r. Chernoi) [Roughness coefficient meas-urements of the Chernaya River channel

The paper presents the determination of the roughness coefficient of the minor river channel, since one of the main design parameters depends on the minor stream, required for a substantiation of design decisions. In accordance with the regulatory documents of the Russian Federation, the roughness coefficient is taken according to the visual characteristics of the riverbed.The purpose of this work is to determine the relationship of the roughness coefficient and dimensionless complexes at different water depths (before and after entering the floodplain).All calculations are performed according to the results of studying the hydrological conditions of the Chernaya river. The roughness coefficient is determined by the numerical method.Analysis of the maximum depth allows to obtain its certain value. It is shown that the hydraulic radius increases at a higher depth. When the maximum depth is deeper, this dependence is nonmonotonic, and when water enters the floodplain, the hydraulic radius strongly differs from the average depth of the minor stream. It is found that before entering the floodplain, there is a significant stochastic relationship between the roughness coefficient, Reynolds number and the dimensionless complex. After entering the floodplain, there is a close stochastic relationship between roughness coefficient and the Froude number. When determining the minimum water levels, the exponent of Chezy's velocity factor in the Manning formula cannot be considered a constant value, because this can lead to a great error.

Особенности построения сетки для моделирования процесса обледенения треугольного крыла сложной формы

The article deals with the problem of modeling the icing of a delta-wing of the X-59 demonstrator aircraft. Three variants of grids for 1.1, 3.8, 9.6 million cells are considered. Wing icing is modeled using the iceFoam solver developed as part of the OpenFOAM package. To solve the problem, two grids are used: the first in the outer region, the second for a liquid film near a solid. blockMesh and snappyHexMesh utilities as part of the OpenFOAM package are used to build the gas phase grid. The quality of the gas phase grid, determined by the standard checkMesh utility, meets all the requirements being checked. However, during the automatic construction of the liquid film mesh, cells with unsatisfactory parameters may be formed, which, for example, include the requirement of limited non-orthogonality of the faces. In this regard, a new algorithm for excluding low-quality calculation cells is being discussed. The simulations were carried out for the X-59 demonstrator wing models on a scale of 1:25 and 1:1 for the case of loose ice. For different-scale models, the invariance of the Reynolds and Mach numbers was ensured. At the same time, the constant parameters in the dimensional form were the water content of the air and the median diameter of water droplets. Patterns of ice formation on the upper and lower parts of the wing were obtained. It is shown that the icing regions of different-scale wing models can differ significantly even when the dimensionless similarity complexes for the gas phase coincide. It is concluded that many experimental and calculated results on the icing of small profiles are difficult to transfer to full-scale profiles. The simulation was performed on the ISP RAS cluster using 48 or 96 processor cores.

Вплив трибологічної ефективності ресурсовизначальних спряжень деталей трансмісії на експлуатаційну надійність транспортних машин

This work examines the conditions of tribological efficiency of couplings of TM transmission discs as resource-determining parts and its influence on the operational reliability of machines. The change in hydrodynamic friction, oil consumption, oil carrying capacity by rotating disks in both laminar and turbulent modes of transmission oil flow is substantiated. The nature of oil discharge from the working surface of the disk in laminar and turbulent modes is considered. Based on the system of the Navier-Stokes equation, the change in the effective characteristics of the coupled transmission discs is substantiated: carrying capacity and oil consumption. The nature of oil discharge from the working surface of the transmission disc is considered, taking into account the friction forces and inertia forces. The dependence of the moment of hydrodynamic resistance on a number of parameters, as well as the relative moment of resistance on the Reynolds and Froude criteria, was investigated as the efficiency of the coupled discs of the transmission of transport vehicles. A qualitative graphical dependence of the moment of hydrodynamic resistance of tribocouplers of disks on the angular speed of their rotation is constructed, with the selection of characteristic zones, and a description of the physical picture of the processes in them is given. The well-founded dependence of the moment of hydrodynamic resistance on a number of influencing parameters, as well as the relative moment of resistance in the multiplicative model representation through criterion dimensionless complexes. The set of processes occurring in the tribo-coupling of disks depending on the angular speed of their rotation in five selected zones has been clarified. It is shown that the efficiency and reliability of the TM transmission depends on the total frictional force acting on the tribo-coupling of the discs, load and operating conditions.

Use of criterial analysis to assess the aero-gas-dynamic perfection of surface-to-air missile

The appearance of surface-to-air missiles (SAM) – in general and their control systems – in particular, should be determined by the experience embodied in the most advanced close analogues based on the main interrelated design conditions. These conditions should follow from the given functional purpose of the object: the method of guidance, the range and height of destruction of air targets, the characteristic type of targets, the method of launching the rocket, the construction of control system. A number of dimensionless complexes have been proposed, which, similarly to the efficiency, express the perfection of certain characteristics of missiles: transport, high-speed, high-altitude. As a necessary prerequisite for analyzing the perfection of the embodied technical solutions, a representative array of tactical and technical characteristics of missiles was used. A method for analyzing the aerogasdynamic perfection of known SAM samples and similar objects based on the theory of similarity and dimension with the use of criterion spaces is proposed. A number of examples of the application of the method for obtaining expert assessments to ensure design work at the stage of forming the appearance of missiles as part of the corresponding complexes and systems are given. An attempt was made to comprehend the relevance of the application and the prospects for further promotion of the “popular” today methods of controlling missiles (impulse micromotors), as well as the principles of “hit-to-kill”. The tendency of improving the copied missile samples and the development of the designated class of equipment is revealed.

Research of hydrodynamics of gas flow filtration through a stationary layer of crushed cotton stalks (wild cotton)

The object of this research is the hydrodynamics of the stationary layer of crushed cotton stalks. One of the most problematic areas is the influence of the physical and mechanical characteristics of the stationary layer of crushed cotton stalks on the hydrodynamics of filtration drying. In the course of research, methods of physical and mathematical modeling are used. Sieve analysis is used to determine the granulometric composition of the polydisperse mixture of crushed cotton stalks. The granulometric composition of the crushed stalks of cotton is determined and the graphical dependence of the percentage of each fraction is presented. The hydrodynamics of gas flow filtration through a stationary layer of crushed cotton stalks are experimentally investigated, and a graphical dependence of pressure losses on the fictitious rate of gas flow filtration is presented. It is found that pressure losses in the stationary layer of crushed cotton stalks are parabolic, which indicates the influence of both inertial and viscous components on pressure losses. The unknown coefficients of the modified Ergun equation are determined on the basis of experimental data. The correlation dependence between the experimental and theoretically calculated values is presented and it is shown that the maximum relative error is 9.6 %, which is quite acceptable for practical calculations. The results of experimental studies are also presented in the form of a graphical dependence of the Euler number on the Reynolds number. Based on the generalization of the experimental data, the calculated dependences are obtained in the form of dimensionless complexes, which describe the hydrodynamics of the gas flow filtration through a stationary layer of crushed cotton stalks. This makes it possible to predict the energy costs for creating a differential pressure, with an accuracy sufficient for practical calculations. The ratio of the experimental values of pressure losses to the theoretically calculated ones, depending on the Reynolds number, is graphically presented. It is shown that the maximum relative error does not exceed 8 %. The proposed generalizations of experimental data will make it possible to determine the energy consumption for creating a pressure drop at the design stage of the drying equipment, as well as to calculate the optimal process parameters and predict its economic feasibility.