METHOD AND RESULTS OF HYDRAULIC CALCULATION OF THE HEAT EXCHANGE SURFACE OF THE ONCE-THROUGH STEAM GENERATOR

Ukraine with her developed machine-building potential can take the deserving place in the production of small modular reactors. One of basic elements of small modular reactors equipment is steam generator. Among different types a deserving place is occupied by once-through steam generator. small modular reactors can exemplify to transport nuclear installation, for example KLT-40S. The calculation of hydraulic resistance is included in designing of steam generators, that it is necessary for the choice of pumps and optimization of structural parameters. In the presented article methodology of hydraulic calculation of once-through steam generator is examined with the coiling surface of heating. As a result of analysis of literature formulas were selected for the calculation of hydraulic resistance for four modes of flow: transverse flow of the coolant over horizontal coils, movement in bent tubes of a single-phase working fluid, boiling water and superheated steam. Results over of calculation of steam generators are brought by power 45 МВт with different structural parameters: diameter of coils, horizontal and vertical pitches of coils location in a bunch, speed of feedwater and coolant. The got results were verified by comparing to data of calculation on the code of ASPEN-TECH. It was found out as a result of research that increase of diameter of coils, as well as the increase of pitches of coils location in a bunch does not reduce hydraulic resistances, as expected, but increases them as a result of worsening of heat exchange and, accordingly, increase of heat-exchange surface. The increase of speed of coolant results in the height of resistance on the side of coolant and does not influence on resistance of working body. The increase of speed of feedwater increases resistance on the side of working fluid and does not influence on resistance of coolant.

ANALYSIS OF THE REVERSING MECHANISM OF LIGHT INDUSTRY EQUIPMENT

To create reliable and highly efficient, en- ergy-saving machines for light industry, it is necessary to study the dynamic processes of movement of the links of the mechanisms of which they are composed. Especially such studies should be given attention for machines, the mechanisms of which have a cyclic nature of action. During the execution of a technological operation in light industry machines with a periodic cyclic movement of the working bodies, an uneven movement of the main shaft occurs. This is caused by the movement of the links of the mechanism with certain accelerations and taking into account the periodic nature of the action of technological loads, which vary in magnitude and direction. The uneven nature of the movement leads to the appearance of additional loads in the kinematic pairs of mechanisms, mechanical vibrations in the mechanical trans- mission systems of motion, leads to the appearance of vibrations and violations in the positioning of the working bodies, affects the techno- logical process of the equipment. Uniform and stable tension of the threads is the key to a high-quality performance of the loop formation process in knitwear. Additional dynamic loads affect the technological tension of textile threads during equipment operation. These loads are caused by the accelerated movement of the links of the mechanism, which is especially important for technological equipment with the pres- ence of a reverse working stroke of its links. In such mechanisms, the values of the angular acceleration of the links and the linear accelera- tion of their individual points can acquire critically permissible values. It is possible to ensure the movement of the working bodies of the machine according to the law for which the tension of the threads will be optimally necessary. To do this, you need to choose the right type of mechanism that sets them in motion. The aim of the work is to conduct a structural-kinematic research of the mechanism of the reversible movement of the needle drum of a knitting machine, which will justify the selection of the required type of mechanism for such equipment. The confirmation of the improvement of the conditions for the formation of loops when knitting on a knitting machine with a reversible needle drum movement, made on the basis of a rocker mechanism, has been obtained.

SIMULATION OF A FLOATING BOLLARD OF A SHIP LOCK BY THE FINITE ELEMENT METHOD

One of the main elements of the lock’s mooring equipment is the floating bollard. Failure of this element of the mooring equipment always leads to great difficulties in organizing ship passes in the lock, in terms of the arrangement of vessels in the lock chamber and the forced withdrawal of locks from work to bring the floating bollards into working condition. Therefore, the analysis of the performance of this element, both at the design stage and during operation, taking into account various options for its loading under the action of changing external conditions, is an urgent task. The article presents the results of a study of one of the structures of a floating bollard of a ship’s lock, which is in real operation. The studies were carried out using the finite element method, in which 3D modeling of the device under consideration was carried out and its stress-strain state was analyzed under various loading options, taking into account the dynamics of mooring operations and weather conditions. A comparative analysis of the created finite element model of the device under consideration with its simplified model in the form of an elastic beam system with a uniform cross section is carried out. A graphic interpretation of the results of the analysis of the stress-strain state of the device under consideration is given, in which the most loaded structural elements are distinguished. The identified location of the places of the largest stress-strain state is proposed to be used as a theoretical basis for the deployment of sensors of the system for alerting the state of the loading of the floating bollard of the ship lock.

HUMAN BODY CAD MODELING IN THE FORM OF A VARIABLE DENSITY OBJECT

High rates of technological progress contribute to the development and improvement of all spheres of human activity, including biomechanical research. The development of new prostheses, orthoses and exoskeletons place increased demands on the determination of the mass-inertial characteristics of the human body. The paper analyzes the existing experimental-analytical and analytical methods for determining the center of gravity of the human body, which are based on the segmentation method. It is shown that the existing analytical methods do not provide complete information about the individual characteristics of the modeled object, when it is implemented using CAD tools, but give only generalized results without taking into account the physical development, health status and other individual characteristics. An improvement of the analysis technique is proposed, which allows increasing the accuracy of determining the mass-inertial characteristics of the human body (including the center of gravity) by its individual anthropometric parameters on the basis of a 14-segment biomechanical model. The article presents a block-diagram and description of the corresponding software module of the calculation, implemented in the Autodesk Inventor environment, in which the human body, when determining its center of gravity, is represented as a complex three-dimension object. This object consists of elements of different densities, while the data on the density of the constituent parts are obtained on the basis of the individual characteristics of the design object by interpolating information from external specialized databases. A comparative analysis of determining the coordinates of the center of gravity of a biological object using both the existing analytical and experimental-analytical segmentation techniques, and the proposed one is carried out. It is shown that the results obtained using the proposed improved analytical technique implemented in CAD, correlate very well with the results of the existing experimental analytical technique with a deviation of 3...4 %.

METHOD AND MEANS FOR MEASURING THE TEMPERATURE OF THE POLE WINDINGS OF THE ELECTRIC MACHINE ROTOR

The temperature of the pole windings is one of the main informative parameters, the deviation of which may indicate the presence of a number of common defects of electrical machines. However, the implementation of high-precision means for measuring the temperature of the pole windings of the electric machine rotor is associated with a number of technical difficulties. The aim is to increase the accuracy of measuring the temperature of the pole windings of the rotor of an electric machine by developing a contactless method and means of measuring the temperature of the pole windings of the rotor in real time. The paper shows that the existing most common methods of temperature measurement have significant disadvantages that limit the possibility of their use for the implementation of means of measuring the pole windings of the rotor of an electric machine. A bispectral pyrometric method of temperature measurement is proposed, which provides simultaneous conversion into voltage of functionally temperature-dependent spectral densities of radiation for two spectrally close electromagnetic waves with subsequent finding of their ratio, which allowed to remove the most significant components of methodical measurement characteristic of classical pyrometers. The design of the bispectral pyrometric measuring system of temperature of pole windings of a rotor of rotating electric machines realized on the basis of the offered method of measurement, suitable for work in a real-time mode together with systems of control of a technical condition and diagnostics is developed.

THE MOTION OF A PARTICLE ON A WAVY SURFACE DURING ITS TRANSLATIONAL CIRCULAR OSCILLATIONS IN HORIZONTAL PLANES

The rough plane is a universal structural element of many machines and devices for sifting and separation of parts of technological material. The motion of particles on the horizontal plane, which performs oscillating rectilinear or circular motion, is the most studied. A wavy surface with a sinusoidal cross-sectional line as a working surface will significantly change the trajectories of their motion. The mathematical description of such a motion will change accordingly. The sliding of a particle in a plane will be a partial case of sliding on a wavy surface when the amplitude of the sinusoid is equal to zero. When the wavy surface oscillates and all its points describe circles, the motion of the technological material changes significantly. The regularities of the motion of material particles on such a surface during its circular translational oscillations in the horizontal planes are investigated in the article. Differential equations of relative particle displacement are compiled and solved by numerical methods. The trajectories of the particle sliding on the surface and the graphs of its reaction are constructed. A partial case of a surface is a plane, and the sliding trajectory of a particle is a circle. An analytical expression to determine its radius is found. During circular oscillations of a wavy linear surface with a cross section in the form of a sinusoid relative trajectory of a particle after stabilization of the motion can be closed or periodic spatial curves. To avoid the breakaway of the particle from the surface, the oscillation mode should be set, which takes into account the shape of the surface and the kinematic parameters of oscillations. With the diameter of the circle, which is described by all points of the surface during its oscillation, is equal to the period of the sinusoid, the trajectory of the relative motion of the particle can be a periodic curve. In this case, the particle moves in a direction close to the transverse, overcoming depressions and ridges. In other cases, the trajectory is a closed spatial curve, the horizontal projection of which is close to a circle. The found analytical dependencies allow determining the influence of structural and technological parameters of the surface on the trajectory of the particle.

THEORETICAL ELEMENTS OF ENERGY MODULAR LAYOUT OF AUTOMOBILE SYSTEM

The article presents a physical and mathematical model of the energy-modular configuration of a vehicle. A technique for modeling the motion of an automobile system with main connections based on the Lagrange equations is considered. This approach allows us to represent the model of the automotive system as a combination of two platforms, force factors and mechanical links, ensures their combination in one workflow. An equation has been drawn up and calculations have been carried out to change the kinetic energy for various modes of motion of the automobile system. The aim of the study is to improve the technology of moving the automotive system using a combination of two mobile platforms. The scientific and practical significance of the work lies in the fact that for the first time a technology has been proposed in which the energy of interaction of two platforms is used to move the automobile system. The research methodology was to establish a mathematical relationship between the generalized force and the dynamics of platform interaction, which is responsible for the movement of the automotive system. The result is the developed geometry of the interaction between platforms in the damping cycle of the interacting platforms. The value of the study, the results of the work carried out make it possible to contribute to the automotive industry. A model is proposed to reduce the energy to create vehicle motion.

DETERMINATION OF THE NONLINEAR PARAMETER AND INTERNAL PRESSURE IN A LIQUID BY THE ACOUSTIC METHOD

An acoustic method is proposed for assessing the molecular properties of a liquid, determining the nonlinear parameter of liquids from the ratio of the first and second harmonics when the acoustic wave changes, and using this parameter to measure the internal pressure. In addition, the proposed method measures intermolecular distances for the studied liquids. In organ fluids, the effects of sound scattering and wave interaction are enhanced. In body fluids, at the molecular level, there is a small amount of microscopic bubbles. This leads to the appearance of the phenomenon of cavitation. These phenomena can be harmful, but not always. There are devices for biological and pharmaceutical technologies, medical devices that successfully use these effects. The paper presents a functional diagram of the experiment, identifies the oscillograms of acoustic signals of finite amplitude at different distances from the emitter. The same devices based on quartz plates 25 mm in diameter with a resonance frequency of 3 MHz were used as the emitter and receiver. This difference of approximately three times the resonance frequencies of the sensors and the acoustic signal ensures the linearity of the amplitude-frequency response of both sensors. Nonlinear acoustic methods are a global trend in biomedical research, as they open up new opportunities and prospects in the development of medical devices. The appearance of higher harmonics in the curvature of the initial harmonic wave of finite amplitude can be used for express analysis of the physical properties of pure liquids and especially aqueous solutions of organic substances. This method of experimental determination of the nonlinear parameter and internal pressure in a liquid is more convenient than the static one, since it does not require the use of high excess static pressures. The proposed acoustic method gives less error than the dynamic one. The accuracy of such a determination can be sufficient to judge the change in the intermolecular interaction in liquids.

AN INDIVIDUAL MASK CREATION USING THE INFORMATION MODEL

The development of individual respiratory protection (masks) during a coronavirus pandemic is relevant. Modern technologies of design and manufacture allow creating masks taking into account individual anatomical features of the person. The paper considers different types of construction of protective masks. It is necessary to create masks taking into account the anatomical features of the person. To address this issue, various countries are holding competitions to create a new generation of masks, such as the Mask Innovation Challenge in the United States. We offer creation of a protective mask with use of modern computer technologies on the basis of information model. The general approach and an option of practical realization of creation of a mask taking into account individual features of the person are considered. The information model has 5 main stages of creating a protective mask. To create a model of the human head, the method of photogrammetry is used, when its three-dimensional model is formed from two-dimensional photographs. On the surface of the head model in the program Autodesk 3DS Max created the basis of the mask frame using retopology technology. Then a three-dimensional solid model of the mask frame was developed, which was tested for mechanical loads when changing facial expressions. The creation of a solid model of the mask frame and simulation of mechanical loads were carried out in the program Autodesk Fusion 360. Fabrication of the supporting frame of the mask using additive technology is simulated. As a result, a mask is created using a replaceable multilayer filter. A further development of the work is the design of a reusable mask using different types of filters.

FACTORS OF THE PVT-COLLECTOR EFFICIENCY FORMATION

Analytical researches of a hybrid solar collecting channel (PVT) are conducted by manufacture electric and thermal energy. The method of researches allows to analyse the following PVT-collector characteristics : a reheat temperature of an absorber and chilling liquid, as well as productivity depending on external and regime working conditions of the device. The work purpose is to work out of a method of calculation of opeating characteristics and definition of rational operating conditions of work of a hybrid solar collecting channel taking into account effective productivity. The complex mathematical model of the local analysis of processes of heat exchange and electrogeneration of a hybrid solar collecting channel for real conditions of a dynamic solar and climatic situation is used. The carried out analysis of heat exchange in alternative conditions showed that efficiency of a heat transport in a collecting channel integral cooling system ηT (a relationship of temperature of an absorber and final temperature of heat-transfer agent) is not a constant and considerably changes under the external and internal factors. It is influenced by intensity of insolation and the heat-transfer agent charge. With growth of these parametres ηT decreases. Existing dependence of electric power of a photo cell on the charge of a chilling liquid is characterised by presence of two expressed sections which are discriminated by rate of a variation of a function. The first of them, with low flux level of a liquid, differs considerable agency of functional parametres. The second one at high intensity differs asymptotic stabilisation of power. The limit values of the transition of the rate of decrease of the function correspond to the fluid flow rate of 0.08...0.085 l/(m2s). These values can be accepted for rationalisation of a refrigerating duty of the photobattery. Generalized dependences for determining the temperature of the liquid at the outlet of the device and the average temperature of the absorber are obtained. These dependences can be used to evaluate the efficiency of conversion of solar energy into electrical and thermal energy in regime optimization problems.