Analytical Dependences Research Articles

The Influence of Steering Axle Design Parameters and Operational Factors on Tire Steering Resistance Torque

This paper presents the results of the study of the kinematics and dynamics of an elastic steered wheel depending on its state, the kingpin unit design parameters, and the tire characteristics in order to obtain dependencies for calculating the tire steering resistance torque in static state and during movement. It was established that when steering in static state, the locked steered wheel is taken as a complex mechanism, and the tire contact patch is rotated about the kingpin axis–support surface intersection point. When turning the unlocked steered wheel, it was determined that the tire contact patch participates in transport and relative motions. The transport motion center is the projection onto the support surface of the center of rotation of the wheel about the kingpin axis. The relative motion center is within the contact patch and is determined experimentally. For both states of the steered wheel, analytical dependencies were obtained for determining the tire steering resistance torque. The results of the analytical studies were experimentally verified on a bench equipped by components and aggregates of a truck, and included an additional rigid false wheel and a special rim. The false wheel made it possible to experimentally determine the tire contact patch transport motion center, and the special rim—to change the knuckle length in the range of 0.22–0.82 m.

Estimation of long-term stability of precision inductance measures using different methods

Abstract Inductance is a physical quantity that characterizes the ability of a conductor to accumulate magnetic field energy when electric current flows. Considering the small number of standards of a similar level of accuracy in the world, it is interesting to study the behavior of individual characteristics of such standards using known research methods. The long-term stability of measures is an important metrological characteristic that characterizes the change in the nominal value of a standard or measure over time. Regular metrological research of the long-term stability of precision inductance measures with nominal values of 10 mH and 100 mH have been carried out since 2009. Analysis of the long-term behavior of precision inductance measures included checking the primary measurement data for randomness and outliers using Abbe’s and Grubb’s tests. The detection of anomalous results significantly affects the estimation of the random error component and the standard uncertainty of the reproduction of the inductance measure. There is a significant change in the inductance of both measures over the entire observation period, which is confirmed by Abbe’s test. At the same time, this change is most significant in the first years, and then the change in inductance occurs slowly. The analysis of the functional change in inductance using the Grabb’s test showed that, depending on the research object itself, different analytical dependencies can be used for describing the functional trend. The criterion for choosing the best approximation can be both the “criterion of the reliability of the approximation” and the standard deviation of the “cleaned” measured data. The practical value of this work is the possibility of accumulating and integrating the obtained experimental data for standards of a similar accuracy class in different countries, which makes it possible to further improve the methods of their construction, stabilization of reproducible characteristics and operational features.

Method for determining the effect of destabilizing factors of digital filters on the multicriteria synthesis of radio communications of aviation robotic devices

The purpose of the research is development of a method for determining the influence of destabilizing factors, such as the unevenness of the amplitude-frequency response (AFC) and the nonlinearity of the phase-frequency response (FFC), in non-recursive digital frequency selection filters on the target function of multicriteria structural-parametric synthesis of radio communications from the payload of aviation robotic devices.Methods. In conducting scientific research, probability theory, mathematical statistics, statistical radio engineering and computational mathematics were used. The study obtained mathematical expressions of the dependence of the probability of error per bit (BER) on the average signal-to-noise ratio when signals pass through symmetrical non-recursive digital filters with quadrature amplitude modulation with a positivity of no more than 4096, signal constellation irregularities of no more than 5, which are the basis for the energy balance of radio lines with aviation robotic devices. The expressions obtained are one of the "foundations" for the implementation of a multi-criteria synthesis of radio systems adaptive to a cognitively formed flight task. In this paper, all the results of the probability of reliability of the received data by means of communication are reflected for the case of rigid decision-making (Gray coding).Results. In the course of the conducted research: 1) a mathematical model of the structural-parametric synthesis of radio communications with aviation robotic devices is demonstrated, which is based on the criteria for minimizing: electronic computing resources with a given noise immunity; radiation outside the operating frequency band; peak factor signals; the effects of narrowband, broadband and structural interference in the radio channel at a given bandwidth; the use of structural and functional nodes specific to the existing information and communication environment; 2) the analytical dependence of the influence of the parameters of one of several structural and functional nodes - digital filters of frequency selection, on the criteria for the synthesis of communication means has been revealed. The paper considers the most common approximating functions - Kaiser, Tukey, Barlett-Khan, Chebyshev, and also shows the influence of the filter order on the equivalent of energy loss in information communication lines of aviation robotic devices.Conclusion. The scientific article presents a method for determining the effect of the uneven frequency response of a symmetrical non-recursive digital filter in devices for receiving and processing radio signals of multicriteria means of communication with the payload of aviation robotic devices. The proposed approach increases the reliability of determining the values of criteria for minimizing electronic computing resources for a given noise immunity, radiation outside the operating frequency band, as well as the use of structural and functional nodes characteristic of the existing information and communication environment.

IMPROVING THE RELIABILITY OF THE THREE-DIMENSIONAL GEOLOGICAL BASIS OF COMPLEX DEVELOPMENT TARGETS

This article proposes a new method for identifying different groups of reservoirs when constructing a three-dimensional geological and hydrodynamic model of the target. Productive formations of the Bajocian and Bathonian stages of the Jurassic system of the Kalamkas field were selected as the object of study. This field is tectonically associated with the northern part of the North Buzachinsky arch, located at the northwestern end of the Turan plate. It was noted that these productive deposits have a complex geological structure, due in lithological terms to uneven alternation of sand-siltstone and clay rocks. In addition, four different reservoir classes are identified within each tier, which are characterized by their own permeability-porosity correlation relationships. As a result, for reliable construction of the filtration field, it is necessary to determine the distribution zones of each of the identified reservoir classes within the reservoir. This is due to the fact that due to the different filtration field, the development of reserves from each group of reservoirs will occur unevenly both in area and in section. In this regard, the integrated Flow Zone Indicator (FZI) was evaluated using the results of laboratory core studies. In order to obtain a continuous FZI parameter for wells without core sampling and laboratory analysis, the results of laboratory studies were compared with the results of well geophysical studies (well logging). As a result, analytical dependence of FZI and log data was obtained. Based on this analytical dependence, new three-dimensional models were constructed and zones of distribution of different groups of reservoirs were identified. To verify the obtained results, the synthetic FZI curve calculated from the obtained analytical relationship was compared with the FZI estimate based on the results of laboratory core studies. It is concluded that the synthetic FZI curve is consistent with the FZI estimate based on the results of laboratory core studies and, therefore, the proposed approach can be used when performing work related to 3D modeling.

Calculation of the Number of Roller Passes When Strengthening Roads Using Recycled Asphalt Granulate

Statement of the problem. Work during the repair, overhaul and reconstruction of highways involves the destruction of old asphalt concrete pavement using the cold milling method. The resulting discrete material is used to strengthen roadsides, and if it is regenerated, it is used to construct base layers and lower layers of covering. The compaction of layers of road pavement is carried out with rollers, the efficiency of which depends on the properties of the resulting material, the power parameters of the rollers, and the technology of work, determined by the number of passes of the roller along one track. Analysis of the work showed that there are no substantiated recommendations for determining the number of roller passes taking into account the properties of the material being compacted. Establishing such dependencies makes it possible to clarify the composition of the compaction machine link when installing structural layers of road pavements while ensuring the required quality of work. Results. Analytical dependencies are presented for calculating the deformation modulus and rigidity of a layer of processed asphalt granulate under load, taking into account the thickness of the layer and the size of the fractions. The stresses under the rollers were determined for different types of rollers and their operating modes, taking into account the technical characteristics. The results of a study to determine the number of roller passes when installing a layer of recycled asphalt granulate are presented, taking into account the size of the fractions and the characteristics of the rollers used. Conclusions. It has been established that both the deformation modulus and the rigidity of the compacted layer can be taken as a criterion when choosing the parameters of the rollers and determining the number of passes of the roller along one track. Based on the results obtained, we can conclude that for a given value of the deformation modulus and the stiffness coefficient of the compacted layer of asphalt granulate, it is possible to determine the number of passes, the type of roller and its operating mode to ensure the required characteristics of the layer.

МАТЕМАТИЧЕСКОЕ МОДЕЛИРОВАНИЕ БОКОВОГО СКОЛЬЖЕНИЯ КОЛЕСНОЙ МАШИНЫ ПРИ ПОВОРОТЕ

The condition for the occurrence of lateral sliding of a wheeled vehicle when turning is determined. Analytical dependences are presented to determine the radius of rotation of the center of gravity of the machine as a function of time, heading angle, acceleration and speed of lateral sliding, and lateral withdrawal of the machine. A mathematical model of the lateral sliding of a wheeled vehicle when turning in the SimInTech program has been developed. A simulation of the lateral sliding of a wheeled vehicle when turning 180 degrees was performed, using the example of the Belarus-80.1 tractor. It shows that the withdrawal of the car in the lateral direction begins at the end of the section of the entrance to the turn, when the radius of rotation of the center of gravity of the car has significantly decreased, but due to the still small values of acceleration and the speed of lateral sliding, the withdrawal in this section is not significant (for the example considered less than 1 cm). In the repartitions of the section of steady rotation (with a constant radius of rotation of the center of gravity of the machine), the acceleration of lateral sliding is constant, but the speed of lateral sliding increases and, accordingly, the withdrawal of the machine in the lateral direction increases (for the example under consideration up to 43 cm). At the beginning of the exit section of the turn, with an insignificant increase in the radius of rotation of the center of gravity of the machine, the acceleration of the side slide decreases, but the speed of the side slide continues to increase until the acceleration of the side slide becomes equal to 0. As the machine moves in the exit section of the turn, the radius of rotation of the center of gravity of the machine increases, the acceleration of the side slide will be negative and directed in the opposite direction from the direction of the side slide speed, the latter decreases, but the withdrawal of the machine in the side direction continues, reaching a maximum value (for the example considered 1.12 m) at a side slide speed equal to 0.

СОГЛАСОВАНИЕ ГЕОМЕТРИЧЕСКИХ ХАРАКТЕРИСТИК ФАКТИЧЕСКОГО ПОВОРОТА КОЛЁСНОЙ МАШИНЫ

Based on the above calculation scheme of controlled curvilinear motion of a wheeled vehicle, it was revealed that the steering trapezoid causes some discrepancy between the kinematics of real and correct rotation. It is established that when adjusting the track width of the machine, the kinematic mismatch between the optimal rolling conditions of the wheels increases, and, consequently, the calculated dependences of the parameters of the ideal turn will not give a satisfactory result when analyzing the actual turn. The minimum theoretical turning radius is taken as an estimated indicator of the turnability of a wheeled vehicle. The conclusion of a multifunctional analytical dependence for determining the theoretical minimum turning radius of a wheeled vehicle, the wheels of which are controlled by a steering trapezoid, is presented. The resulting formula includes the longitudinal base of the machine, the pin track, the angles of rotation of the inner and outer steerable wheels. A comparison of the calculation results according to the developed and known formulas is given, which confirmed the complete convergence. It was found that, for example, an increase in the pivot track of the machine by 0.2 m leads to an increase in the theoretical minimum radius of the actual turn by 16.5%, and the distance from the continuation of the rear axle to the instantaneous center of rotation by 45.07...98.02% when the angle of rotation of the inner steering wheel changes from 20° to 40°.

Eкспериментально-розрахункове визначення коефіцієнтів гідродинамічної моделі кавітуючих насосів рідинних ракетних двигунів

Cavitation phenomena in liquid-propellant rocket engine (LPRE) pumps not only affect the power performance characteristics of the pumps, but they also affect the pump dynamics and pogo vibrations. The theoretical characterization of cavitation phenomena in LPRE pumps is not a widely used practice because theoretical and experimental data are in unsatisfactory agreement. Because of this, use is made of approaches that employ experimental data. The goal of this work is to determine the coefficients of a hydrodynamic model of cavitating LPRE pumps throughout the cavity existence region based on the experimental frequencies of cavitation oscillations and cavitation self-oscillation boundaries. In determining the cavity elasticity and negative resistance, use was made of the experimental cavitation oscillation frequencies of 26 LPRE pumps differing in dimensions and capacity. In determining the cavitation resistance distribution coefficient and the cavity-due disturbance transfer time, the experimental cavitation self-oscillation boundaries of 14 more pumps were used. To extend the cavity elasticity determination region, the extrapolation dependence of the cavity elasticity in cavitation stall regimes was updated. To make the stratification of the cavity resistance dependence more uniform in the range of large discharge coefficients, incipient cavitation numbers were refined. Using he qualitative dependence of the cavitation resistance distribution coefficient obtained from theoretical transfer matrices of cavitating pumps and its lower estimate (at zero disturbance transfer time) and upper estimate (for a uniform stratification of pump transfer matrix determinants), its analytical dependence was found. Using it and the coefficients of a mathematical model of cavitation oscillations on the cavitation-self oscillation boundary, disturbance transfer times were found and approximated.

Identifying the parameters and operation modes of the cavitation apparatus taking into account the influence of the processing material

The object of this study is dynamic pressure that takes into account the main parameters of technological process. Under real conditions of cavitation apparatus operation, a discrepancy between actual and calculated parameters of 30–50 % was found, which significantly reduces the efficiency and quality of material processing. The problem was solved through a joint study of the movement of the acoustic apparatus and the technological environment as a single structured system taking into account the influence of materials. This is a peculiarity of the approach and distinctive features of the results in comparison with existing ones, in which the research was conducted separately for the processing material and the cavitation apparatus. The model proposed in the work reflects the elastic, inertial, and dissipative parameters in the equations of motion, provided that their changes are taken into account, both in the acoustic apparatus and in the technological material. This approach has made it possible to reveal the physical essence of the interaction and analytically describe their joint movement. The resulting analytical dependences made it possible to calculate and propose numerical values of vibration amplitudes in the range of 4.0...20.0 μm, sound pressure values in the range of 5.0...30.0∙105 Pa for media with a viscosity of (10–200)∙10-3 Pa∙s. With the set value of the amplitude, it is possible to assign the necessary parameters for the implementation of the cavitation process. The developed calculation algorithm ensures the reliability of the accepted models and parameters of the cavitation apparatus. The proposed approach of joint study of the movement of the acoustic apparatus and the environment is expedient to use for the practical implementation of ultrasonic treatment. In particular, such processes as dispersion, emulsification, mixing, extraction, and others, in order to increase their efficiency

Development of a control algorithm for a boost converter with the possibility of dynamic correction of control system parameters

RELEVANCE of the study lies in the development of an algorithm for controlling a DC voltage converter capable of providing a high-quality transient process with a wide change in the input parameters of the control object, affecting its nonlinear properties. purpose. THE PURPOSE. To consider methods for the development of continuous and discrete control systems for a step-up DC voltage converter and to obtain an analytical dependence of accounting for the nonlinear properties of the converter that affect the quality of regulation of the output voltage of the voltage stabilizer METHODS. The method of the average geometric root was chosen as a method for calculating the coefficients of the DC voltage converter control system, and the current circuit is adjusted using the technical optimum method, and the voltage circuit using the symmetric optimum method. The obtained analytical solutions of mathematical models and simulation models were compared in the SimInTech software environment. results. RESULTS. The simulation results show that the analytical solution of the mathematical model of the voltage stabilization system has a shorter transition time than the simulation results. This is due to the fact that in the mathematical model according to which the continuous control algorithm was synthesized, the presence of a power input filter, as well as the degree of their precharge, is not taken into account. Because of this, the transition time on simulation models is slower, applied 4 times than in the mathematical model. conclusion. CONCLUSION. When comparing the algorithms with each other, it can be seen that the algorithm obtained by converting a continuous algorithm by the Tusten method has the shortest transition time than all other algorithms. The continuous algorithm and the algorithm obtained by the inverse Euler transformation method have a speed close to each other, and the algorithm obtained by the direct Euler transformation turns out to be the slowest.

EXPERIMENTAL RESEARCH OF THE MAGNETIZATION AND DEMAGNETIZATION PROCESSES OF THE VECTOR-CONTROLLED INDUCTION MOTOR

Experimental research of the processes of magnetization and demagnetization for the motionless vector-controlled induction motor was performed, according to a linear law with a variation in the duration of these processes. The methodology of research during which the orthogonal components of the stator and rotor currents were recorded in the rotor flux reference frame, the rotor flux module and the energy of the total losses in the stator and rotor copper is described. The main characteristics and parameters of laboratory equipment and facilities are given. From the point of view of minimizing copper losses, the existence of the optimal duration of the investigated transient processes has been experimentally proven. The results of experimental studies with high accuracy coincide with calculations based on previously obtained analytical dependencies, which confirms the admissibility of the assumptions made during theoretical studies. References 10, figures 7, tables 2.

Analytical relations for fields and currents in magnetic-pulsed «expansion» of tubular conductors of small diameter

Introduction. This work was initiated by the problems of cardiovascular diseases, which are one of the main causes of mortality of the population of our planet. More than ten years ago, in 2012, approximately 3.7 million people died of acute coronary syndrome worldwide. The fight against such pathologies is carried out with the help of so-called stents, the manufacture of which can be carried out by the method of magnetic pulse «expansion» from hollow metal cylinders. The limited production possibilities of magnetic pulse «expansion» were caused by the minimum cross-sectional size of the inductor-instrument, which can be practically manufactured. Other tools are required to perform this operation. Novelty. A system of magnetic-pulse expansion of thin-walled pipes of small diameter with an inductor that excites an azimuthal electromagnetic field in the case of direct current passing through the processing object and in the absence of its connection in an electric circuit with an inductor is proposed. Purpose. The main analytical dependencies for the characteristics of the electromagnetic processes taking place in the inductor systems for the expansion of cylindrical conductive pipes of small diameter when direct passage of current through the processed object and when it is not connected to an electric circuit with an inductor (insulated billet) is derived. Methods. The solution of the boundary value problem with given boundary conditions was carried out by applying Laplace transforms and integrating Maxwell’s equations. Results. Analytical expressions were obtained for the main characteristics of the processes: the intensities of the excited electromagnetic fields and currents in the system depending on the parameters of the studied systems. The analysis of possible technical schemes for solving the given problem indicated the choice of the optimal variant of an effective system of magnetic-pulse «stretching» of thin-walled cylindrical conductors of small diameter. Practical value. Based on the qualitative analysis of the obtained results, recommendations for the practical implementation of the proposed system were formulated. The obtained dependences allow us to give numerical estimates of the effectiveness of excitation of magnetic pressure forces on the object of processing and to choose directions for further improvement of the magnetic pulse technology for solving such problems. References 23, figures 2.

Trajectory-based synthesis of a slider-crank mechanism for applications in inertial vibration exciters

Slider-crank mechanisms are widely used in various industrial and technological machines. This paper considers a generalized diagram of a slider-crank mechanism, on the connecting rod of which an imbalanced mass can be fixed. In such a case, the slider-crank mechanism can be employed as an inertial vibration exciter. The aim of this research is to justify the geometric parameters of the mechanism to ensure a predetermined elliptical trajectory of the imbalanced mass motion. The research methodology involves the analytical derivation of the motion equations for a connecting rod point and solving the problem of synthesizing the geometric parameters of the mechanism based on the given trajectory of this point. The obtained results are presented in the form of displacements and trajectories for the connecting rod point of a specific slider-crank mechanism. The major novelty of this research lies in the further development of the theory of slider-crank mechanism synthesis for use in inertial vibration exciters. The derived analytical dependencies can be utilized by designers and engineers in the development of new types of vibration exciters for various industrial and technological vibratory equipment.

Application of experimental planning methods for an analytical description of the areas of operability of marine electromechanical systems

The topic of the study is to consider the possibility of using experimental planning methods to mathematically describe areas of performance in relation to marine electromechanical systems. A definition is given and a graphic illustration of the field of operability is provided. It is shown that information about the boundary of the field of operability allows solving the most important tasks of controlling the state of ship electromechanical systems of various functional purposes. Possible ways of solving the problem of constructing a field of efficiency and the difficulties of their practical implementation are given. The method of analytical description of the operability domain is considered, which assumes an independent approximation of each hypersurface that makes up the operability domain. It is shown that for such an approximation it is convenient to use polynomial dependencies, which can be obtained as a result of using experimental planning methods. The main advantages of this approach are considered, including the possibility of solving the problem in the case of a high dimension of the space of primary parameters, in the space of which the area of operability is built. It is noted that in order to obtain a unified analytical description of the field of operability, the properties of logical R-functions can be used, which make it possible to make the transition from logical functions to analytical dependencies. It is proved that polynomial dependencies have the properties of R-functions and can be used in such a transformation. The resulting analytical description of the health area is universal and does not depend on the configuration of the area itself. Unlike the known methods of analytical approximation of the field of operability, it is characterized by an exceptionally low methodological error and allows us to solve with high reliability the problem of parametric synthesis of marine electromechanical systems according to the criterion of the reserve of operability, as well as the tasks of evaluating and predicting their condition during operation. The considered example clearly demonstrated the sequence of solving the problem of analytical description of the field of operability and allowed us to conclude about the complex configuration of this area even for special cases and the simplest electromechanical systems.

Calculation of wind load on an axisymmetric reflector antenna with arbitrarily oriented reflector relative to the wind flow

One of the main factors in assessing the strength and stiffness of parabolic reflectors of stationary antenna systems is research of the force effect of the wind flow. The magnitude of the wind load depends on the wind speed and aerodynamic characteristics of the structure, which are determined by the geometry and orientation of the reflector relative to the direction of the wind flow. In order to determine extreme values of output parameters, calculations must be performed over a wide range of positions of the reflector and directions of wind flow. The paper proposes a method for estimating the loaded state of an axisymmetric reflector antenna with an arbitrary orientation of the reflector relative to the wind flow. This method is based on the analytical dependence of the angular position of the antenna relative to the direction of the wind flow, which allows to determine aerodynamic loads, with an arbitrary orientation of the reflector relative to the wind flow. It does not require CFD modeling for a given wind direction, and is based on predefined loads calculated in the basic coordinate system.

Design of radio-transparent shelters using an optimized mathematical apparatus for analytical strength calculations

The main aspects of the design of radio-transparent shelters have considered, taking into account the provision of the required strength, mass-centering radio engineering characteristics, as well as the temperature of the environment inside the radome at all stages of product operation. The use of new structural and functional composite materials in modern technology makes it possible not only to reduce the total weight of the structure by 30 – 35%, but also to significantly increase the reliability of operation compared to materials based on epoxy binders. It is promising to use heat-resistant thermosetting binders and materials based on them for the manufacture of friction units that require lubrication and as high-temperature thermal insulation of critical elements of aerospace engineering. Analytical dependences make it possible to select a preliminary RPR design and, at the initial design stage, assign a minimum wall thickness. However, further solution of the complex problem of ensuring the shape, stability and strength using the simulation of the stress-strain state of radio-transparent composite structures is advisable to carry out by the finite element method. The disadvantages of fiberglass include the fragility of the fibers, low density and a tendency to shrink. In this regard, the analysis of materials for the manufacture of fairings for the protection of electronic equipment have currently being carried out and the technique used to analyze the possibility of using fiberglass fairings can be applied to various composite materials.

Теоретические исследования процесса смешивания кормов центробежным смесителем

The article presents theoretical studies aimed at understanding the physical processes occurring in the production of compound feeds using a centrifugal cascade mixer, which open up new horizons in optimizing feed production technology. Special attention in these studies is paid to the analysis of the mixing process, which, as it turned out, is closely interrelated with the principles of operation of the dispenser. As a result of the analysis, it was found that the dispenser and mixer should be considered as a single system, regardless of the mixing mechanism used in the production process. This made it possible to develop a cascade mixer of feed materials of centrifugal type and continuous action, which is an innovative solution in the field of feed production. This mixer provides a homogeneous mixture of loose feed components and can be integrated into production lines for the preparation of both feed and combined mineral briquettes. The key advantage of the proposed mixer is the use of a centrifugal force field, which, unlike the gravity field, provides more efficient mixing. In this case, the process of preparing compound feeds can be represented as a sequence of three key stages: the metered supply of components, the introduction of one component into the composition of another, transportation (removal) of the finished product from the working area of the mixer. The research allowed us to obtain analytical dependences of the components of the centrifugal force on the angular velocity of the rotor and its radius. This allows you to optimize the operating parameters of the mixer to achieve maximum mixing efficiency. During the research, a mathematical model of the spatial motion of a particle in a mixer was developed. The model is presented in the form of Lagrange equations of the second kind, the generalized coordinates of which are the displacement of the particle along the cone and the polar angle of the particle position. This makes it possible to solve the optimization problems of centrifugal mixers according to a given objective function. Thanks to the conducted research, it was possible to develop an innovative mixer that provides a homogeneous mixture of components of loose compound feeds. The use of centrifugal forces in the mixer made it possible to increase the mixing efficiency and ensure that the final product meets the requirements of the formulation. The research results are of great practical importance and can be used to improve feed production technologies. Keywords: COMPOUND FEED, FEED MIXTURE, MIXER, DISPENSER, CENTRIFUGAL MIXER, PARTICLE MOTION IN THE MIXER

ВИЗНАЧЕННЯ АЕРОДИНАМІЧНИХ ХАРАКТЕРИСТИК ЛІТАЛЬНОГО АПАРАТА З НАДЗВУКОВИМ ШВИДКОСТЯМИ ПОЛЬОТУ

The aircraft aerodynamic characteristics at supersonic flight modes can be determined with a high level of accuracy through testing the aircraft in wind tunnels or through time-consuming three-dimensional and analytical computational methods. However, in certain cases when the aircraft aerodynamic characteristics are already known within a given Mach number range for supersonic flight, it is possible to develop a relatively simple mathematical model for the aircraft aerodynamic characteristics at supersonic speeds using the aerodynamic properties of the supersonic wing leading edge for flight speeds Mf ≥ 1.2M. The object of the study is the aircraft aerodynamic characteristics at supersonic flight speeds. The subject of the study is the impact of the aircraft geometric features on the mathematical model, which is used to determine its aerodynamic characteristics in the supersonic flight speed range. The study hypothesizes that to determine the aerodynamic characteristics of an aircraft at Mf ≥ 1.2, it is sufficient to identify the values of the aircraft aerodynamic parameters at a flight speed of Mf =1.2 and then use aerodynamic analytical dependencies for the supersonic wing leading edge to determine these parameters at Mf ≥ 1.2. A mathematical model of the aircraft aerodynamic characteristics in the supersonic flight speed range was developed. Coefficients of drag polar and zero-lift drag for the reference mode Mf = 1.2 have been identified by the developed mathematical model. Then, the Mach number range for the aerodynamic characteristics of the NASA 1044 configuration has been extended to supersonic speeds of Mf = 1.8…4.0. The resultsof the aerodynamic calculations, obtained in the form of dependencies of the drag polar and zero-lift drag coefficients on Mach number, and the aircraft polar plot, have been compared with known NASA data for the 1044 configuration aircraft. The average modeling error of the aircraft aerodynamic characteristics in the supersonic speed range is less than 3%.

To determine the cut height of fallen stems

Abstract A significant part of the harvested crops lies down by the beginning of harvesting, and the harvesting of fallen bread cereals is accompanied by an increase in grain losses. The productivity and quality of the cutting devices of harvesting machines, which are used for harvesting crops, largely depend on the cut height of the fallen stems. It was found out that with an increase in the cut height, grain losses increase, and with its decrease, the efficiency of agricultural machinery decreases due to clogging of mechanisms with plants and soil. The article considers the analytical dependencies between the characteristics of the height of the cut stems, the soil surface and the cutting machine in its general movement across the field. The basic formulas of such dependencies are given.

On the Dependence of the Surface Tension of a Spherical Droplet on its Charge

Qualitative analytical dependence of the value of the coefficient of the surface tension of a liquid on the density of the electric charge on its surface was derived from general theoretical positions by asymptotic methods. It is shown that the value of the surface tension coefficient of a liquid decreases with an increase in the density of the electric charge on the surface of the liquid.