No 6 (2018)

Articles

Mathematical modeling of the chemical kinetics of the processes of fuel ignition in the combustion chamber of a diesel engine on start modes

Bondar' V.N., Malozyomov A.A., Kukis V.S., Omel'chenko E.A., Malozyomov G.A.

Abstract

The article presents results of calculation and theoretical research, aimed at ensuring the compliance of diesel engines with the requirements of regulatory technical documents for starting characteristics. In course of the study, the mathematical model of chemical kinetics, ignition processes and fuel combustion in the combustion chamber was developed. Model can be used for predicting diesel engine starting characteristics. Model was realized as separate software. The developed mathematical model is implemented in the three-dimensional gas-dynamic model of processes in combustion chamber. In the course of the fuel combustion reactions chemical kinetics computational studies on diesel start-up modes, it was determined, that to ensure ignition of fuel in combustion chamber, required gases local temperature should be at least 1350 K. The permissible proportion of carbon oxide in the gases, produced by intake air heater, should not exceed 40 %. It is shown, that increase of compression ration, at a constant gas temperature, has little effect on the chemical kinetics of pre-flame processes and combustion reaction rate. It is revealed, that temperature of the combustion chamber walls has a prevailing effect on the possibility of fuel ignition. The wall temperatures have been determined, to which it is necessary to heat the diesel engine using pre-start heating and start facilitate tools for various environmental temperatures, crankshaft rotational speeds, compression ratios and concentration of the intake air heater combustion products. The developed mathematical model and software are used in current research and development work of the South Ural State University to create new and modernize existing diesel engines of various types, produced by Chelyabinsk tractor plant.
Tractors and Agricultural Machinery. 2018;(6):3-11
pages 3-11 views

Influence of the deseeding device design on the air flow characteristics in the combing chamber of the flax harvester

Shishin D.A.

Abstract

The speed and airflow distribution at the exits window of the combing chamber of flax harvester were studied. The aim of this study is to determine the influence of the design of the deseeding combing device on the speed and distribution of the airflow at the outlet of the comb-chamber. Standard metric technique was used to detect the average air speed by examining the field of airflows. In the experiment, the serial and new designed deseeding devices were installed on an laboratory facility that allows modeling the processes of combing of flax stems and heaping. The experiment was carried out at a drum rotation frequency of 230, 280 and 330 min-1. Mathematical processing of the data was carried out with «Stadia»© and «MS Excel»© programs. The graphs of airflows’ distribution at the outlet of comb chamber are presented. Obtained equations shows regressions of the speed of the airflow from the speed of the combing drum. It is concluded that the airflow over the cross-sectional area at outlet of window in deseeding device is unequal. The highest flow rate occurs in the upper and left parts of the window. It is established that the change in the design of the stripper device has practically no effect on the average speed of the air flow. Speed of the combing devices in rate of 275...285 min-1. have been recommended to use as an optimal one.
Tractors and Agricultural Machinery. 2018;(6):12-16
pages 12-16 views

The unit for making dusty lime fertilizers

Sedashkin A.N., Milyushina E.A., Kostrigin A.A., Dragunov A.V.

Abstract

The article presents some results of comparative tests conducted at N.P.Ogarev Mordovia State University of unit when making dust-like lime fertilizers with serial and experimental centrifugal working body. The influence of the translational velocity of the unit on the uneven distribution of cement dust across the width of the grip is determined. Observations have shown that using mechanical spreading (for example, a centrifugal disk) of fertilizers with different grain-size characteristics, large particles under the action of the initial velocity acquired during the descent of the disk fly further, and small (dusty) particles fall on the soil near the center of the disk. Therefore, it can be assumed that a combination of different methods of action (mechanical and pneumatic) on the particles of fertilizers in the process of their introduction will give the desired result, i.e. qualitative distribution of particles, regardless of their particle size distribution and characteristics. Analysis of the literature showed that the work on improving the centrifugal disk, in order to increase the air flow, turned out to be ineffective and the machines with such working bodies were not widely used. In our opinion, the full potential of the pneumatic-centrifugal working body is revealed when it is designed according to a disc-fan type, which involves fixing the blades to the lower surface of the disc and differentiating air flow under the particles of fertilizers sown on the peripheral zones of the working width. To check the efficiency of the unit, we carried out comparative tests when scattering cement dust with a serial and experimental centrifugal working body at three speeds of the unit, 2,5, 3,5 and 4,5 km/h. Taking into account these proposals, we made a pneumatic-centrifugal working body and carried out laboratory tests. As a result of the laboratory studies, it was established that the uneven distribution of the pulverized mass across the width of the grip, depending on the working speeds, the values of which are indicated above, varied from 15 to 30 %; the smallest irregularity, both at maximum and minimum values of feeds, was obtained at an aggregate speed of 4,5 km/h and was 15 %, and the highest under the same conditions with an average speed of 2,5 km/h. Thus, the equipment of serial centrifugal spreaders with the proposed working body turns them into universal machines capable of introducing all types of mineral fertilizers, calcareous materials and their mixtures, of any particle size distribution and application rate.
Tractors and Agricultural Machinery. 2018;(6):17-21
pages 17-21 views

Differential distribution of hardening materials on cutting blades of soil processing machines

Myalenko V.I.

Abstract

The cutting blades of the working bodies of the soil-processing machines due to their intense abrasive wear largely influence the operational reliability and performance of the working machinery. To increase the service life of the blade the carbide materials are harden, the appropriate expenditure of which requires the definition of rational zones and geometric parameters of more or less of their application to the blade. A method is proposed for determining the geometrical dimensions of a layer of hardening materials of soil-processing machines previously applied to cutting blades. The algorithm of the method consists in first identifying the magnitudes of the normal pressures acting on the side of the treated soils on the blades and building the corresponding plots of the nature of the change in loads on the blade surface. The nature of the distribution of loads on the blades of soil-processing machines is rational to determine by special application of wearable materials over the friction surface. The rapid wear of these materials with different intensity in different areas of friction characterizes the distribution of real loads acting on the blades from the treated soils. Then, after analyzing the plots, taking into account the characteristics of the treated soils, the properties of the reinforcing materials applied to the blades and the expected blade life, the size of the applied layer of reinforcing materials is determined. Then, after analyzing the plots, taking into account the characteristics of the treated soils, the properties of the reinforcing materials applied to the blades and the expected blade life, the size of the applied layer of reinforcing materials is determined. The geometry of the distribution of reinforcing materials and the specific dimensions of their cross-sections are chosen in a way similar to the values of the curves for the epures of normal pressures arising under actual operating conditions. Thus, the proposed differentiated distribution of reinforcing materials over the surface of the blades of soil-processing machines allows for rational use of materials under conditions of abrasive wear of the working bodies and provides the necessary operational durability.
Tractors and Agricultural Machinery. 2018;(6):22-26
pages 22-26 views

Increase of durability of working bodies of tillage machines by applying metal-ceramic coatings

Titov N.V.

Abstract

Currently, the most promising to increase the durability of the working bodies of tillage machines are metal-ceramic materials that are applied to the cutting surfaces in the form of coatings. A promising way to create metal-ceramic coatings is carbovibar hardening (CVH). When using CVH, a multicomponent paste containing a metal matrix, ceramic components and an activator of the arc burning process (cryolite) is applied onto the hardened surface, which, after drying, is melted by a vibrating carbon electrode to form a metal-ceramic coating. The aim of the work is to substantiate the feasibility of using a matrix powder on an iron basis in the composition of multicomponent pastes for CVH in order to improve the structure and physicomechanical properties of metal-ceramic coatings and increase the durability of the working bodies of tillage machines. When conducting research, iron-based powders and nickel-based powders were used as the matrix material of multicomponent pastes for the CVH, and boron and silicon carbides were used as ceramic components of the pastes. The greatest microhardness (1354 HV) are metal-ceramic coatings obtained on pastes containing matrix powder and boron carbide. The microstructure of the obtained coatings is dense and practically non-porous, and their wear is 3,6 times less than the wear of 30 GR steel adopted as the reference standard. The use of the matrix powder in the paste leads to a significant reduction in the microhardness of metal-ceramic coatings (1033 HV using boron carbide and 942 HV - silicon carbide), they contain a significant number of pores of various sizes. The obtained data confirm the feasibility of using iron-based powder as a matrix material of multicomponent pastes for CVH. According to the results of the research, the paste should contain 60 % of powder, 30 % of boron carbide and 10 % of cryolite. Its use will significantly increase the durability of the working bodies of tillage machines, reinforced with metal-ceramic coatings obtained at CVH.
Tractors and Agricultural Machinery. 2018;(6):27-31
pages 27-31 views

Principles of development of the technological process of tillage in arid conditions of the south of Russia

Parhomenko G.G.

Abstract

In the arid conditions of the southern regions of Russia the cultivated crops experience a lack of moisture. At the same time, the agrotechnical cultivation of the soil becomes important. In a fractured porous massif of the treated soil, there is a loss of moisture from the depth of the reservoir during physical evaporation. Physical evaporation of moisture in dry conditions leads to a drying soil degradation. When loosening only the surface layers, pseudo-scaling of the lower part of the treated layer may occur, leading to hydrolysis degradation of the chernozem soil. Objective: to determine the basic requirements for agrotechnically appropriate technological process of tillage in dry conditions and working bodies for its implementation. The development of the technological process of tillage in dry conditions of the south of Russia should be based on the principles of moisture accumulation inside the reservoir due to the use of thermal diffusion processes. The temperature difference between the layers of the soil inside the reservoir moves the heat flow, contributing to the emergence of the process of thermal diffusion of moisture. To do this, tillage must be done differentially with varying degrees of compaction in layers. During the layer-by-layer processing of the soil inside the reservoir, a moisture accumulating layer is formed due to the combination of both types of heat exchange: insolation and radiation. At a depth of 10-15 cm the flow of moisture available to the root system of crops intersect. This process is carried out by a unified design, developed by the method of the basic unit with common and replaceable parts (subsystems). The combination of subsystems is implemented constructively on a single carrier system according to a certain allocation principle, taking into account the duration of relaxation of the internal stresses of the reservoir, which is 0,09-0,11 s for the black-earth soil in arid conditions. The distance in the longitudinal direction between the subsystem blocks should be at least 0,2 m. In this case, the structures of the working bodies are developed on the basis of the interrelation of the parameters and modes of operation with the physical and mechanical properties of the soil.
Tractors and Agricultural Machinery. 2018;(6):32-39
pages 32-39 views

Justification of the width of the outlet of the screw conveyor and distributor

Bychkov I.E., Kupreenko A.I., Bychkova T.V., Isaev H.M.

Abstract

The subject of the research is a screw conveyor-distributor of grain with an empty hole along its casing. This design eliminates the need for leveling the grain mound, moving the conveyor or using a rotary tray to evenly distribute the unloaded grain. The purpose of the study is to find the dependence of the width of the outlet hole on the parameters of the conveyor-distributor. A laboratory installation was made and studies were conducted on the expiration of wheat grain through a drain hole of various widths. Laboratory installation is a container made of plastic rectangular pipe open at the top. The transverse membranes are inserted at an equal distance into it. They divide the entire capacity along its length compartments. In the bottom of the pipe, a hole in the form of a slot of constant width is made. Eruptive hole is closed from the bottom of the side retractable flap. Under the discharge opening, trays were installed, each under its own compartment, into which the grain is poured. Having removed the valve, with the help of time-lapse videotape, the time was taken during which the grain was completely poured through the empty hole. An experiment with different width of the outlet holes and with different mass of grain in the compartments was conducted. The width of the hole was changed from 7 to 13 mm. It has been established that under conditions of limited height of the grain column above the hole, the flow rate through the drain hole does not depend on the height of the grain column above the hole. The dependence of a single grain flow on the width of an outlet is constructed. When the width of the outlet hole is 7 mm the outflow of grain does not occur. An expression is obtained that describes the shape of the outlet hole, depending on the design-mode parameters of the screw conveyor. A graph showing the shape of the outlet hole with the given design-mode parameters of the screw conveyor was constructed.
Tractors and Agricultural Machinery. 2018;(6):40-44
pages 40-44 views

Visualization of the results of mathematical modeling of dynamic processes in mobile power facilities

Kuznecov A.N., Polivaev O.I., Loshchenko A.V.

Abstract

To analyze, evaluate and demonstrate the behavior of created mathematical models of complex dynamic objects, developers often have to use graphic materials, which are very complex and uninformative. Modern software mathematical packages allow not only to solve systems of differential equations describing the behavior of objects but also to create animated representations of these processes. To do this, the MathCAD environment has a system variable FRAME, the value of which can vary from 0 to 999. This variable allows to alternately refer to the lines of the stored matrix of the numerical solution of systems of differential equations and display the new states of the elements of the analyzed dynamic system, with a simultaneous time-lapse recording of these displays. To represent real modeling objects on two-dimensional graphs, from which the animation is formed, various geometric primitives are drawn: squares, rectangles, and circles with different degrees of freedom. Function prototypes are formed to create matrices for representing these primitives. The geometric parameters or the position of the representation matrices are rigidly associated with the elements in the row of the numerical solution matrix pointed to by the FRAME system variable. The result of using this variable is an animated representation that demonstrates the behavior of objects and allows you to quickly identify errors made in the simulation. In this article, on the example of the analysis of the behavior of the structural elements of the mobile power facilities when moving through a single roughness of a given shape, the technique of creating an animation of the described process is shown. The problem of finding a numerical solution of systems of differential equations by the Runge-Kutta method of the 4th order in MathCAD mathematical package is also considered.
Tractors and Agricultural Machinery. 2018;(6):45-52
pages 45-52 views

Determination of the transfer function of the pneumatic suspension of the seat on the hydraulic pulsator stand

Lyashenko M.V., Pozdeev A.V., Chumakov D.A., Iskaliev A.I.

Abstract

The article presents the results of tests of the pneumatic suspension of the seat of the Sibeco company with a scissor guide mechanism on a single-point stand with a hydraulic drive manufactured by the Indian company BiSS. Pneumatic seat suspension is one of the most important components of the vibration protection system of the human operator of the vehicle. For researchers, engineers and designers involved in improving the level of comfort of new automotive equipment, it is very important to determine the dynamic characteristics of the systems of suspension of existing models of seats in order to further carry out constructive measures to improve their vibration protection properties. The most important dynamic characteristic that assesses the vibration-proof properties of the seat suspension is the transfer function. The purpose of the test is to determine the transfer function. The set includes metal elements connect the actuator of hydraulic pulsator stand and cargo, simulates the sprung mass, suspension seat, and a force sensor integrated into the stand design, and sensors accelerations fixed end to the upper frame and the base suspension. The studies were carried out on the modes of harmonic excitation of the considered system of suspension with a certain frequency. Time realizations of signals from acceleration sensors were recorded with an accuracy of 0,001 g, which were then processed to obtain RMS values and calculate the value of the transfer function. During the processing and analysis of the data obtained, the dependences of the transfer function of the seat air suspension on the frequency of the kinematic effects of the stand were built and the resonance frequency ranges were revealed. In conclusion, the nature of changes in the experimental transfer function of the seat suspension system with an increase in the frequency of disturbances is also determined.
Tractors and Agricultural Machinery. 2018;(6):53-57
pages 53-57 views

Improved working tool for loosening the soil in the rows of berry crops

Gordeev O.V., Gordeev V.O.

Abstract

Technologies for the care of berry plantations involve the use of manual labor for tillage between the bushes of plants. The lack of mechanized soil care between plant bushes stops many farmers from planting new plantations. The purpose of the research is to improve the layout of the working tool for loosening the soil in the rows of berry crops. An experimental setup with a device for inter-waste tillage was developed and tested at the institute. It was found that the asymmetric working body with a radius of rotation of the teeth loosening more than 0,5 m practically does not work. The minimum and economically feasible radius of rotation of the loosening teeth located at the same distance from each other on the arc of the circle of the asymmetric working tool is justified. The dependence of the loop width of the elongated cycloid and the length of the soil tillage area on the distance between the plant bushes in the rows of berry crops to determine the required number of loosening teeth is presented. The scheme of the improved working tool in the form of a rotating asymmetric circular sector with loosening teeth located on the arc of the circular sector is presented. An expression defining the angular measure of the circular sector is obtained.
Tractors and Agricultural Machinery. 2018;(6):58-62
pages 58-62 views

Quality control of power transmissions and undercarriage systems using digital technology

Petrishchev N.A., Lavrov A.V., Kryukovskaya N.S., Kapustkin A.O., Sayapin A.S., Pospelov A.P., Pryadkin V.I.

Abstract

Violation of the technical condition of the transmission and running systems leads to operational and economic costs, violation of the technical indicators of mobile power tools laid down by the manufacturer. It also has a negative impact on the environment. At present, only a few domestic and foreign companies have equipped the equipment they produce with digital systems for monitoring the technical condition of power transmissions and running systems, and even then by one or several parameters. These are systems that measure the level of wheel slippage of the tractor, the temperature and pressure in the tires, the angle of inclination of the tractor, as well as the systems that control the optimality of the conversion of engine power to tractive force. The main mass of tractors has no control system during operation and diagnostics of components and assemblies of the transmission and chassis systems is carried out by the tractor operator «by eye», based on his experience and fairness. This often leads to serious violations and equipment operates in modes and loads close to failure. Therefore, it is necessary to introduce into the design of modern technology integrated system for monitoring the state of power transmission and running systems, based on the use of digital technologies. As an experiment, a prototype model of such a control system was developed, including various sensors, both embedded and external, the hardware of the Arduino microcontroller platform, as well as widely available applications for the smartphone, allowing to measure and display on the screen the necessary information about the current state of the units and components. The smartphone is supposed to be mounted in the cab of the tractor. The prototype was tested and can be considered successful. Therefore, in the future it is planned to expand its functionality and add elements.
Tractors and Agricultural Machinery. 2018;(6):63-69
pages 63-69 views

Justification of required number of vehicles when combined cabbage cleaning

Alatyrev S.S., Cruchinkina I.S., Alatyrev A.S., Fedorov D.I.

Abstract

During combine harvesting of cabbage, products are transported from the field to the vegetable store mainly in the body of the vehicle in bulk or in containers. In the first case in the place where vegetable vehicles are unloaded manually, and in the second case - using a forklift. At the same time, vehicles are significantly idle while unloading vegetables, especially in the first case. In this regard, in order to assess the quality of service of vehicles, the process of unloading them is modeled using the queuing theory. The essence of the occurring phenomena is described and the indicators of the quality of functioning of the vehicle maintenance system in the vegetable storehouse during the delivery of products in bulk and in containers are calculated, and recommendations on its rational organization are formulated. Taking into account the rational organization of the vehicle servicing system on unloading, their required quantity in the considered cases is justified.
Tractors and Agricultural Machinery. 2018;(6):70-76
pages 70-76 views

Substantiation of machine and tractor fleet compositions and their efficiency on the basis of universal mobile power facilities for the main regions of the South of Russia

Bur'yanov A.I., Goryachev Y.O., Chervyakov I.V.

Abstract

Technical equipment of agro-industrial production of the Russian Federation has a steady tendency to deterioration of its condition due to aging technology both physically and morally. This may very soon directly threaten the country's food security. The situation can be normalized on the basis of a wide application of solutions based on the maximum universalization of the village. equipment, primarily mobile power facilities, and the ability of units to carry out a wide list of works on their basis - from tillage to harvesting. Such developments are carried out both by leading foreign firms and in the territory of the Russian Federation, in particular, at the FSUE ANC «Donskoy», a unit of North Caucasus institute of agricultural mechanization and electrification (formerly VNIPTIMESH) together with OJSC «Gomselmash» (Belarus). This paper presents the results of assessing the feasibility of using universal power tools with special technological adapters in the southern zone of the Rostov region; Each zone is represented as farms, with crop rotations typical for it and with three arable land sizes of 1250, 2500, 5000 hectares. The implementation of mechanized work is carried out using serial equipment (basic version) and a combination of serial equipment and the inclusion in the composition of alternatives of universal energy means, with a set of technological adapters for harvesting grain crops, corn for silage and grass for haylage. As a result, the composition of the machine and tractor fleet and performance indicators of model farms were calculated. The improvement of the main indicators of efficiency in the application of a universal energy tool with a set of technological adapters is observed in all the models under consideration. The reduction in direct operating costs is up to 22 % in comparison with machine and tractor fleet based on serial equipment, the reduction in the cost of the car park is up to 29 %, the growth of net discounted income is up to 26 %.
Tractors and Agricultural Machinery. 2018;(6):77-84
pages 77-84 views

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