Experimental Installation Research Articles

ИССЛЕДОВАНИЕ ВЛИЯНИЯ ЭЛЕКТРОЗОНИРОВАНИЯ НА СРОК ХРАНЕНИЯ СПЕЛОЙ КЛУБНИКИ

Preserving the freshness of fruits and berries is of great importance not only for their taste, but also for preserving their nutritional properties. Ozonation is one of the highly effective methods for destroying bacterial microflora and preserving food for a long time. Ozone is a strong disinfecting gas with a powerful disinfecting effect; biochemical processes are greatly reduced in ozonated products. Studies to study the effect of ozonation on the preservation of freshness and appearance of berries were conducted on the example of strawberries of the "Black Prince" variety. Experiments on electrozoning of ripe strawberries were carried out in laboratory conditions in the Chuvash State Agrarian University. For this purpose, an experimental installation was developed and implemented to study the effects of ozonation. In a series of one-factor experiments, the preservation, appearance of berries and the amount of microflora after 6 days of storage were determined. Ozonation of berries was carried out in special containers at an ozone concentration of 6 mg / m3, lasting 2 hours - 2 times a day. The appearance and taste of strawberries treated with ozonation for six days has not changed; the number of microorganisms on the surface of berries during storage for up to six days corresponds to the standards of GOST 29187-91. A visual inspection of the berries in the control sample on the sixth day of storage showed that 90% of the berries were affected by mold fungi. Unprocessed berries lost their shape, softened, putrefactive microflora appeared; the surface area affected by mold fungi reached more than 90%. Thus, ozonation has shown high efficiency in preserving the freshness, appearance and quality of strawberries during storage. Ozone treatment significantly reduces the development of pathogenic microflora and prevents spoilage of berries. This method can be recommended to extend the shelf life of fruits and berries in the food industry.

Hydrodynamic properties of propellers with large blade-area ratio and truncated blade in free water

In the literature exist data about the hydrodynamic characteristics of propulsion systems, which include a duct and a fixed-pitch propeller with a truncated blade shape (Kaplan propeller), which has a relatively small blade-area ratio of 0.55. Usual such propellers has a very high loading coefficient, which entails the need to increase propellers blade-area ratio in order to prevent the occurrence of developed cavitation. The article presents the results of the first stage of research, which included testing a series of four-blade truncated propellers with a blade-area ratio 1.0 in free water. The tests were carried out in the towing tank of Admiral Makarov State University of Maritime and Inland Shipping on experimental installation, which include a special hydrodynamic stand. A series of tested propellers were 3D printed from PET-G plastic. A preliminary assessment showed that the chosen diameter of the models will ensure the achievement of supercritical Reynolds numbers at a rotation frequency of about 20 s–1. However, during the tests, it was found that the rotational speed must be increased to 30 s–1, which, in turn, led to a reduction in the test program due to the regime limitations of the experimental equipment. Nevertheless, the analysis of the test results made it possible to build a “hull” and “machinary” diagrams according to the Papmel form. An assessment of the strength of the models was carried out, which showed that the stresses arising in the root of the blade are significantly less than the allowable ones. The obtained results expand the design possibilities of Kaplan propellers with water-jet propulsion units, as well as a part of the “propeller-nozzle” propulsion complex.

An Identification-Based Control Method for an Overhead Crane with a New Combined Sensor Placement

This paper is devoted to an automatic control method for an overhead crane under the current parametric uncertainty of the crane, transported cargo, and exogenous disturbances. The control objective is to move the cargo in the horizontal plane to a point ensuring the final delivery of the cargo to the designated place while parrying the angular oscillations of the suspension and reaching given dynamic characteristics. The approach is based on a control scheme with a current parametric identification algorithm, an implicit reference model, and “simplified” adaptability conditions to track cargo movements directly. The control law generates a given trolley speed for the servo drive. The passport data of the crane installation are used to select the control law parameters. Unlike previous publications on the topic, the solution proposed below is simpler, more reliable in terms of operation, and less expensive. This is achieved by placing a combined sensor (an accelerometer with an angular rate sensor (ARS)) on a suspension cable near the crane trolley and applying, first, an algorithmic solution without the preliminary calculation of the ARS drift and, second, a current parametric identification procedure of higher efficiency. Computer simulation results are provided to confirm these advantages of the new solution. A similar example is implemented on an experimental installation.

IMPLEMENTATION OF NATURAL EXPERIMENTS IN PHYSICS USING COMPUTER VISION

Laboratory experiments in physics are a fundamental basis for studying physical phenomena occurring in nature and a methodological tool that provides visibility of the learning process and conducting experiments is important for the formation of students’ scientific worldview, deep understanding of physical laws and increasing interest in the study of physics. Existing in universities and schools, in addition to traditional ones, modern tools, technologies and approaches, such as virtual reality, augmented reality, computer modelling, online laboratories, virtual laboratory and others, are additional tools for improving the quality of the learning process and teaching techniques, which do not replace full-scale experiments, but only supplement them. In our opinion, for better learning, laboratory installations in physics are needed, with the help of which students can carry out real-life experiments and can broadcast them using innovative computer technologies for distance learning. To implement this task, we reviewed and analysed existing laboratory installations, identified their advantages and disadvantages, and then designed and developed alternative digital experimental set-ups for studying physics phenomena in laboratory conditions of educational institutions based on computer vision technology and presented the results of the study in this article. In carrying out the research tasks, effective methods of conducting scientific research were used, such as theoretical substantiation of the issue, experimental testing of the developed hardware and software systems and computer final processing of experimental data. In summary, the research described in the paper presents an innovative mechanism for integrating object tracking based on computer vision to improve the quality of measurements and new ways of conducting physics experiments. The mechanical laboratory complexes we have developed consist of hardware and software parts. The software part consists of server and client parts. The hardware consists of the main part - the scene, where the physical process takes place, i.e. where a physical object is located, such as a mathematical pendulum, an inclined plane, etc., with the help of which many physical phenomena and processes in mechanics can be demonstrated, and an additional part where a microcomputer and a camera are located. The operating principle of the laboratory installation is based on the use of computer vision technology, i.e. a system for monitoring the ongoing physical process, consisting of a digital camera for image processing, object identification and data export, and a microcomputer for processing experimental data. The use of the experimental installations in the process of teaching physics is a new model of teaching with a promising future in secondary and higher education, and the installations themselves will become tools for offline and online learning, due to the use of computer vision technology, revealing new opportunities and approaches to teaching.

Full-duplex two-way no-relay cross-media communication method based on acoustic wave conversion

Abstract Due to the difference in acoustic impedance between water and air, the water interface becomes a natural barrier. Underwater sound waves will bounce when they propagate to the water surface. Electromagnetic waves and light waves in the air will rapidly attenuate after passing through the water surface and going underwater, making it difficult to complete air-water cross-media information transmission. In this article, we first analyze the theoretical characteristics and vibration model of the water surface after medium collision, and develop a new full-duplex communication method across the air-ocean medium, which does not rely on relay equipment and only uses three transmission media in the air. Propagate signals in the sea channel physical field to achieve two-way communication, using the mutual conversion between laser, acoustic, and radio frequency signals to fill the gap in cross-media communication technology that can simultaneously achieve two-way, full-duplex and non-relay. It has been verified through experimental installations carried out in laboratory water tanks and large comprehensive anechoic pools that it is able to achieve full-duplex communication links across the air-sea surface, indicating that the combination of laser acousticization and radio frequency-acoustic wave conversion can be used across medium full-duplex wireless communication provides a feasible method for communication that breaks through the water interface.

Метод обработки сигналов токов статора асинхронного двигателя для диагностики обрыва стержня ротора

The study is relevant due to high requirements to the reliability of the operation of auxiliary mechanisms of thermal power plants (TPP). The main source of mechanical power of auxiliary mechanisms of TPPs is high-voltage induction motor with squirrel cage rotor (IMSC). One of the most difficult causes of emergency shutdown to detect early is a broken rotor bar. The breakage of IMSC rotor bar is of latent character. It can be for a long time without considerable influence on the machine operation mode. Nevertheless, the fact of the breakage can be considered as an emergency condition of IMSC, and the consequences of leaving the groove of the magnetic core are irreversible. Scientifically, early diagnostics of IMSC rotor bars breakage of TPP auxiliary needs is both a difficult and extremely urgent task. The existing methods of diagnostics of such damage are based on measurement and analysis of vibration and acoustic physical quantities. The most common electrical parameter, used as a source of information, as a rule, is current consumption. And most of methods are based on Fourier analysis. The purpose of the study is to develop a mathematical algorithm to process digitized curves of stator phase currents to diagnose high-voltage IMSC. The theory of electric machines, the method of analytical approximation of experimental data, the method of regression analysis have been used to solve the problem. Experimental data is obtained, and testing of the algorithm is conducted on an experimental installation with a 0,4 kV induction motor with a modified design of the active part of the rotor developed for physical simulation of IMSC broken rotor bar. This paper proposes a new method of digital processing of stator current signals based on the regression analysis method for diagnostics of IMSC rotor winding. The authors have developed an algorithm for mathematical processing of digitized stator current curves based on regression analysis in the cosine-sine basis to identify the diagnostic sign of failure of one rotor bar of IMSC rotor. The authors have determined the number of harmonic components that best describe the initial signal from the point of view of the balance between saving computational resources and accuracy of approximation. A mathematical algorithm to detect the rotor bar breakage of an induction motor based on regression analysis of stator currents has been obtained and tested. It allows to detect rotor circuit damage with 97 % accuracy. At the same time the diagnostic sign changes its level when one bar breaks by 5 %. It is recommended to adapt the algorithm to the programming languages of microprocessor relay protection units.

Features of achievement of limiting speed values of track tests of ballistic type aircraft

The development of high-speed ballistic aircraft with speeds exceeding 1000 m/s is currently a priority abroad and in Russia. The effectiveness of new such products is confirmed by track tests at the speed of their use. Test sites with rail tracks exist in almost all countries, for example in the USA there are more than 15 of them. Double-rail, monorail and various combinations thereof, differing in length, width of the rail pair, rails and the design of the track itself, including a sealed shell over the rail track to fill it with a lighter one environment. The longest track in the USA is Holloman AFB, located in New Mexico with a length of 15536 m. They have track ranges with different lengths and their own special design in England, France, Germany, Canada, Italy, Japan, India, China, Korea, Turkey and other countries, including African continent. High-speed range tests in Russia are carried out on the experimental installation “Rocket Rail Track 2500”, located on the territory of the FKP “GkNIPAS named after L. K. Safronov”. The experimental installation consists of a rail track placed on a special base, providing the necessary vertical profile of the track with sections of ascent and straight horizontal movement, as well as a technological descent section for braking moving technological equipment. The product under test is placed on a rocket track sled moving along rails on sliding supports. To accelerate the track carriage, solid fuel rocket engines are used, the thrust of which is selected based on ballistic calculations to achieve the required test speed. The length of the track plays an important role in achieving the maximum acceleration speeds of moving track equipment. The enormous aerodynamic drag, proportional to the square of the speed of movement of the carriage, when tested at high speeds, leads to the need to reduce the midsection and mass of the mobile unit. An increase in engine thrust leads to an increase in the weight and cost of track equipment, as well as to the need to increase the safety margin of sliding supports. However, an increase in test speed can be achieved by replacing the air medium with gases that have a significantly lower density, for example, helium. Track testing of new aircraft or their elements, although cheaper than flight testing, is quite expensive. In this regard, work on the theoretical assessment of replacing the medium from ambient air with helium, as well as with a mixture of helium and air at different concentrations in an indoor gallery on a track rail track, is a new, relevant and practically useful task. The work performed a numerical simulation of the problem of supersonic flow around a helium-air mixture at different volumetric ratios. Numerical values of aerodynamic resistance were obtained at a sled speed of 830 m/s. The results of numerical calculations of the motion dynamics of a 3D model of monorail track equipment, which are planned for use in conducting full-scale fire experiments, are presented.

FEATURES OF WELL KILLING IN CONDITIONS OF CARBONATE RESERVOIR AND HIGH GOR

The article presents the results of studies on the use of well killing technology in fractured carbonate reservoirs of the Republic of Bashkortostan under conditions of loss of kill fluid and high GOR of the product. The geological and technical conditions of the Metelinskoye field are summarized, and the factors complicating well killing before routine and workover are described - reduced reservoir pressure during operation, previous large-volume salt-acid treatments, and the presence of hydrogen sulfide.The article substantiates the choice of invert-emulsion solutions (IER) for killing wells in the Metelinskoye field, taking into account the experience of using various killing technologies in the Volga-Ural oil and gas province. The authors have determined the physicochemical and rheological characteristics of kill compositions based on IER of various densities. An increase in the effective viscosity at high shear rates and the limit shear stress of the IER with an increase in the density of the composition was revealed. Taking into account the high risks of gas breakthrough during well killing in the Metelinskoye field, studies were also conducted to assess the gas-retaining capacity of the IER on an experimental installation by extruding the composition from a metal capillary. It has been shown that the gas holding capacity of these compositions with increasing density is described by an equation with a power function and a high degree of reliability. The effect of hydrogen sulfide neutralizer addition on IER properties was investigated. In order to increase the success of killing, the IER-based killing technology was selected and adapted to the existing conditions. The better blocking ability of higher density formulations has been confirmed. Successful well tests. To reduce the risks of using the IER and optimize the consumption of reagents during the further use of the technology, organizational and technical measures for killing and subsequent repair of wells were developed and implemented. The results of this work can be used in wells of the Ural-Volga region, Eastern Siberia and Timan-Pechora province with the presence of losses and a high gas factor, the repair of which is complicated by the lack of fluid circulation and the presence of excess pressure at the wellhead with signs of gas shows.

Effect of electrophysical treatments on the storage life of potatoes and other vegetable crops

To prevent the progression of various infectious diseases, seed and planting material must undergo treatment with ultraviolet (UV) radiation at an intensity of 10-15 kilojoules. This necessitates studying the impact of UV radiation on products as they move in a flow along a conveyor belt. (Research purpose) The study aims to evaluate the feasibility of using ultraviolet radiation to improve the storage indicators of potato and other vegetable crops. It also assesses the technological parameters in both laboratory and production settings to ensure a reduction in contamination. (Materials and methods) To determine the optimal technological parameters of a machine for processing vegetable crops and potatoes before storage in the post-harvest processing system, an experimental installation was created and the electrophysical effects on storage quality indicators were examined. For the study, the most common vegetable crop varieties were selected, in particular, Lady Rosetta potato, Vitaminnaya-6 table carrot and Bordeaux 237 table beet. These crops are cultivated under various soil and climatic conditions across the Russian Federation. (Results and discussion) A methodology has been developed to assess the quality of seed material after the storage period, including the justification for the time interval, air mixture temperature parameters and ultraviolet radiation optical modes. The optimal parameters for processing potato tubers, carrots, and beets have been determined. The study examined the impact of ultraviolet exposure with established parameters on the disease development in carrot and beet crops, caused by the studied phytopathogenic microorganisms at temperatures of 2 and 25 degrees Celsius. (Conclusions) The indicators of the spread and development of infectious diseases in the studied vegetable crops show a decline trend when the translational speed of root crop movement is 0.7 meters per second, the interaxial distance between ultraviolet radiation sources is 0.1 meters, the distance from the sources to the roller surface of the conveyor belt is 0.05 meters, and a constant dose of ultraviolet exposure is applied.

Опыт организации лабораторных работ по физике как пример практико-ориентированного обучения

The article discusses the application of a practice-oriented approach to the training of cadets studying in the specialty 56.05.01 Logistics in educational organizations of the Federal Penitentiary Service of Russia. The requirements for the training of specialists in the rear services of the penal enforcement system are given. As an example of practice-oriented training, a methodology for organizing laboratory work in physics is proposed. The structure of the academic discipline and the specifics of its implementation in an educational organization are described. The concept of laboratory work, general issues of the organization of laboratory work and methods of their implementation are considered. The description of the methodological support of laboratory classes, the device of the applied laboratory layout, as well as the measuring equipment used is given. The stages of laboratory work, the order of assembly of the experimental installation by students, layouts of tables for entering empirical and calculated data, as well as the preparation of a report on laboratory work are described.

Механизм влияния электрического поля на процесс модифицирования серого чугуна

A diagram of an experimental installation for measuring the electrical resistance of a gray cast iron melt is presented, where a gauge based on a Kelvin double bridge is used. It is shown that the value of the specific electrical resistance of gray cast iron varies depending on the type of conditioning agent. Experimental data on the difference in specific resistivity values for various gray cast iron nucleating agents are presented. Changes in the values of electrical resistance under the influence of electric field treatment of inoculated cast iron melt are also given. Comparison of the strength values of gray cast iron with its values of the electrical resistivity of the cast iron melt after the electrical field exposure showed their simultaneous change. The decrease in the values of the electrical resistance of hot iron due to the electric field exposure is shown and it corresponds to an increment in the strength of inoculated cast iron. The effectiveness of the electric field exposure on the process of inoculation is determined by thermal ionization of the chemical elements included in the conditioning agent. The maximum increase of these parameters after electric field exposure when using FS75 nucleating agent is shown. The mechanism of the influence of an electric field on the cast iron solidification for the inoculation process of FS75, containing 75 % silicon in its composition, is described. The dependence of the efficiency of electric field exposure on the composition of the nucleating agent for gray cast iron is shown. A physical model of the effect of an electric field exposure on the process of cast iron inoculation is found. The possibility of influencing the hydrodynamic situation in the melt of gray cast iron and changing the rate of dissolution of nucleating agent particles by means of electric field exposure is given

Experimental installation of a reference source of low currents for calibration of electrometers

Today, there is great scientific interest in the possibility of implementing reference sources of low currents based on single-electron pumps using the single-electron tunneling effect and the modern definition of the SI system. However, the practical use of this effect in everyday metrological practice has not yet reached the stage of widespread use. Typically, for routine calibration work in laboratories, either mass-produced instruments (low current sources and meters, electrometers) are used, which are calibrated against higher standards, or specially designed precision current sources. The article describes a reference installation developed on the basis of the VNIIFTRI, where in the mode of generating ultralow currents the principle of forming a linearly increasing voltage on a reference capacitor is used. A simplified block diagram of the reference setup is shown. Issues of practical adjustment of modern electrometers are considered. The generalized results of participation in international comparisons on low currents EURAMET.EM-S44 “Comparison of ultra-low DC current sources” conducted by national metrological institutes in 2018–2020 are presented. The results of a metrological study of the calibration factor Q and an example of calculating the uncertainty budget of measurements carried out at the VNIIFTRI as part of these international comparisons are presented. The research described in the article to increase the accuracy of measurements of small and ultra-low currents of this level has valuable practical significance in the field of electrical measurements, in aeroionometry and metrology of ionizing radiation.

Experimental studies of the impact of fluid sloshing in the tank on the dynamic characteristics of the “wing model – fuel tank” system

Flexible response of the airframe structural elements under operational loads are one of the main sources of fatigue damage accumulation. It is known that fuel sloshing in tanks can change the dynamic (frequencies and shapes of natural oscillations) and dissipative properties (oscillation damping decrements) of an elastic system, including partially or completely fuelfilled tanks. It is specified that fuel sloshing in tanks due to the additional oscillation energy dissipation of the elastic system can have a significant impact on both the fatigue and aeroelastic characteristics of aircraft structural elements. Theoretical and experimental studies, applicably to the majority of currently operating transport aircraft, have shown that when modeling dynamic phenomena and solving aeroelasticity problems, fuel can be considered conditionally solidified, which actually does not affect the resultant effect. The advent of modern heavy transport aircraft with a high aspect ratio wing and four engines on pylons under the wing has led to a considerable change in the dynamic picture of the aircraft interaction with the environment. The main feature is that, under this arrangement, the first horizontal bending mode of the wing is embedded in the main flexible modes that determine the dynamic response to external effects. In this case, the model of solidified fuel can have a significant impact on the accuracy of predicting dynamic loads and, as a consequence, on the quantitative characteristics of durability and aeroelasticity. The article presents the results of experimental studies of the impact of fluid sloshing in the tank on the dynamic characteristics (frequencies of natural oscillations and amplitudes of forced oscillations) of the “wing model – fuel tank” system. The design of the experimental installation and the methodology of conducting experiments are described. During the experiment, the tank was partially filled with liquid or full, and horizontal bending modes of the wing model, for which considering liquid sloshing in the tank is the most relevant, were studied. The tank refueling levels are determined at which the maximum effect of the system oscillation damping is achieved due to energy dissipation under liquid sloshing. The effect of various factors (presence of a top cover, internal structural frame, perforation in the structural frame) on the amplitudes and frequencies of forced oscillations is analyzed.

The scientific landmarks for the development and evaluation of the effectiveness of vibration and noise absorbing materials

The mastic compositions with vibration and noise absorbing properties have been developed to reduce the level of noise and vibration in the low- and high-frequency range of the spectrum. Evaluation of the effectiveness of the developed vibration and noise absorbing mastic compositions “Vibroshtil” and “Vibroshtilmaxi” was carried out on an experimental installation by the method of free damping of plate vibrations with the determination of the decrement of vibrations. Mastic compositions are characterized by a high value of the sound absorption coefficient and the coefficient of mechanical losses in the range of operating speeds. The introduction of developed vibration and noise absorbing materials with an extended spectrum of action at the workplaces of workers will reduce the level of vibration and noise in the low- and high-frequency range of the spectrum by 7–15 dB and create safe working conditions. The main characteristic of the vibration and noise absorbing composite is the sound absorption coefficient, the value of which is in the range from 0 to 1. The main advantage of these compositions over the existing ones is the ease of manufacture, the ability to apply them to any surface by spraying or puttying.

ВЛИЯНИЕ СОСТАВА ОЧЕСАННОГО ЗЕРНОВОГО ВОРОХА НА ЭФФЕКТИВНОСТЬ ЕГО СЕПАРАЦИИ НА РЕШЕТЧАТОЙ ПОВЕРХНОСТИ

The separating ability of the lattice surface when working with combed grain heaps of various fractional compositions was studied. The scientific hypothesis of the study is the assumption that with an increase in the mass fraction of chaff in the heap, the separation efficiency should decrease due to an increase in the volume of grain with a constant mass of the sample of the heap under study as the grain content decreases due to the larger volumetric mass of the latter compared to the chaff. It is a legitimate assumption that the passage of a larger volume of heap through the holes of the lattice surface requires more time, that is, the separation rate should decrease. Experimental studies were carried out on a combed grain heap of wheat variety Moskovskaya 56 with a relative humidity of 12%. The mass fraction of grain in the heap varied from 100 to 60% in increments of 10%. The experimental installation was made on the basis of the grain elevator of the KZS 1218 combine harvester, in which, instead of the dismantled lower wall, a lattice surface with longitudinal holes 900 mm long and 12 mm wide was installed. The installation simulated the operation of the inclined chamber of a combine harvester, the lattice bottom of which should separate free grain from the combed heap and direct it for cleaning, bypassing the threshing apparatus. In this regard, the speed of the scraper conveyor was 3 m/s. The heap that passed through the holes in the lattice was caught, after which it was disassembled into fractions and accounted for. As a result of the experiment, it was established that as the mass fraction of grain in the heap decreases, the separation rate of the latter within the zone of variation of the initial parameter decreases by 4%. Therefore, it is advisable to first remove a significant portion of light impurities from the combed heap before it enters the inclined chamber.

STUDY OF THE INFLUENCE OF MECHANICAL CLEANING DEVICE SPIRAL FIN GEOMETRY ON TRANSPORTING CUTTING PROCESS IN HORIZONTAL WELLS AT EXPERIMENTAL SETUP

The problems of creating an axial load and clearing cuttings when drilling horizontal wells are considered.The purpose of the work is to study a combined drill string and the geometry of spiral fins of mechanical cleaning devices to achieve optimal load on the bit and clean cuttings when drilling wells with a long horizontal section.Main objectives: study of the influence of spiral fins ofmechanical cleaning devices on the transportation of sludge in the annular space on the developed experimental installation; designing the optimal layout of a combined drill string with mechanical cleaning devices, determining the area of its effective application; conducting a comparative analysis to determine the main advantages of the compiled layout. The use of mechanical cleaning devices has been proposed, in particular the design of a lock-centralizer-turbulator, which makes it possible to improve the cleaning of the horizontal part of the wellbore by turbulizing the flow of the flushing fluid and lifting the cuttings to the region of higher flow rates. An experimental installation was designed, manufactured and put into operation to conduct a study of the processes of transferring load to the bit and cleaning the well from cuttings. Research and comparative analysis of various configurations was carried out according to the nature of their influence on the process ofsludge transportation using an experimental setup. The results of a study on rational spiral fins of a lock-centralizer-turbulator are presented. An optimal combined drilling assembly with mechanical cleaning devices was designed, a comparative analysis was carried out, and the main advantages of the constructed assembly were determined.

Research of Energy Efficiency and Environmental Performance of Vehicle Power Plant Converted to Work on Alternative Fuels

The use of alternative fuels remains an important factor in solving the problem of reducing harmful substances caused by vehicles and decarbonising transport. It is also important to ensure the energy efficiency of vehicle power plants when using different fuels at a sufficient level. The article presents the results of theoretical and experimental studies of the conversion of diesel engine to alternative fuels with hydrogen admixtures. Methanol is considered as an alternative fuel which is a cheaper alternative to commercial diesel fuel. The chemical essence of improving the calorific value of alternative methanol fuel was investigated. Studies showed that the energy effect of burning an alternative mixture with hydrogen additives exceeds the effect of burning the same amount of methanol fuel. The increase in combustion energy and engine power is achieved as a result of heat from efficient use of the engine exhaust gases and chemical conversion of methanol. An experimental installation was created to study the work of a converted diesel engine on hydrogen–methanol mixtures and thermochemical regeneration processes. Experimental studies of the energy and environmental parameters of diesel engine converted to work on an alternative fuel with hydrogen admixtures have shown that engine power increases by 10–14% and emissions of harmful substances decrease.

Production of aluminum foam using an alternative porophore

Subject of research: blowing agent in the form of natural CaCO3 powder to obtain high-quality aluminum foam material. Purpose of research: selection of the optimal type of foam as a pore-forming element and production of aluminum foam with special functional properties. Methods and objects of research: when studying the gas-forming properties, the residual substances and thermal stability of the powder were determined using a thermogravimetric analyzer TG-DTG, DSC. The processes of obtaining aluminum foam samples sintered in a protective environment on an experimental installation are considered. The object of research is the resulting CaCO3 powders, as well as the determination of the physical and mechanical properties of aluminum foam samples. Main results of research: production of foamed aluminum with special functional properties with the introduction of powder blowing agent CaCO3. Selection of the optimal component of the amount of powder injected into the metal matrix of the substance, based on the physical properties of the resulting material.

Tactics of Fish Behavior in the Water Flow during Starvation

Individual movement parameters for the zebrafish Danio rerio and the Prussian carp Carassius gibelio during starvation for 12 days have been determined in an experimental hydrodynamic installation circular tank. The fishes represent two tactics of behavioral responses on starvation. The tactics of unidirectional responses have been manifested in the movement of individuals in one direction relative to the water flow on days 2–5 of starvation. The tactics of multidirectional responses have been manifested on days 10–12 of starvation as movements in different directions relative to the water flow. The population advantages of such behavioral tactics of fish response to an unfavorable factor are considered.

Numerical and laboratory experimental analysis of the movement of silicone cleaning pigs through 90-degree bends pipe

Analysis of the stress-strain state of cylindrical cleaning pigs manufactured of hyperelastic material during their movement through the pipe bends of the pipelines, identification of maximum contact forces' points, and places of their separation from the inner wall. The effect of the dynamic friction coefficient between the pig's lateral surface and the pipeline's inner wall on the value of the maximum equivalent von Mises stresses in the pig is investigated – determination of the required pressure for the passage of the pig through pipeline bends.The finite element method performs numerical modelling of the pigs' movement through pipeline bends is performed. The non-linear properties of a hyperelastic pig material (a silicone compound with a hardness of 30 units on the Shore scale) are described by the potential Yeoh strain energy model. The contact interaction of the pig with the inner wall of the pipe bend is modelled by a surface-to-surface contact with dynamic friction coefficients of 0.1, 0.2, and 0.3 between them. For research, pigs with a length of 60 mm, 75 mm and 90 mm with a convex front and a concave rear end were manufactured and modelled. The experimental unit was designed and mounted from metal and glass pipes, between which pipe bends were placed with a bending angle of 90 and a bending radius of 1.5 DN. The metal pipeline has an internal diameter of 49 mm and a total length of 5.3 m, and the glass pipeline is 54 mm and 5 m, respectively. The experimental installation made of glass pipes was designed for visual observation of the dynamics of the pig movement through the glass pipeline bend and from metal – for measuring the pressure during the pig movement along the straight sections and the pipeline bend. To verify the correctness of the numerical modelling, the fully calculated deformations of the cleaning pigs in the bends of the pipeline were visualized and compared with photographs of the deformations of the pigs during their movement through the glass bends of the pipelines.The bending of the pig in the pipe bend and contact forces increase equivalent von Mises stresses in the pig. Moreover, during the movement of the pig in a pipe bend, the distribution of equivalent von Mises stresses in it, as well as its deformations, changes continuously. It depends on the stage at which it is located. Numerical modelling and experiments have established that when the pig is at the stage of movement in the middle part of the pipe bend, due to bending, its lateral surface is partially separated from the inner wall of the pipe bend. With this, on the convex side of the pipe bend, the pig is separated from the wall in the front and rear parts and on the concave side – in the middle part. This separation of the lateral surface of the pig from the inner wall of the pipe bend results in the formation of a gap and cross-flows through the pig, reducing the pressure drop on it, which can lead to its sticking. For pigs made of silicone compound with a hardness of 30 units on the Shore scale to pass pipeline bends with a bending angle of 90 and a bending radius of 1.5 DN, the pressure in the pig space shall be at least twice as high as the pressure required for the pig to move along a straight section of the pipeline.Modelling and experimental studies were performed for pigs made of silicone compound. Therefore, subsequent studies will establish the influence of other hyperelastic materials' physical and mechanical properties on the pig movement along the pipeline bends.The results obtained in this study allow for determining the possibility of pigs passing through the pipeline bends of gas gathering systems at gas fields and gas networks, determining the necessary pressure for this and, if necessary, optimising the geometric shape and dimensions of the pigs passing through the pipe bends.The influence of the location of a solid pig made of hyperelastic material in the pipeline bend and the coefficient of dynamic friction on the stress-strain state of the pig is studied. The article contains original experimental units designed and installed to study the movement of pigs through pipeline bends.