The processes to form the compositions of loose materials in centrifugal mixers of continuous action have been considered. Based on the method of discrete elements, a mathematical model of the movement of particles in the rotor of the centrifugal mixer was built, taking into consideration their geometric and physical-mechanical parameters. To assess the extent of influence of these parameters on the nature of particle movement, a well-known mathematical model in the form of a system of differential equations was used, which was built on the basis of classical laws of mechanics. The process of mixing particles of two loose materials under different initial conditions of movement was modeled. The trajectories of individual particles along the bottom and side wall of the rotor were calculated. The results of the research reported here have established that the model built on the basis of the discrete element method makes it possible to improve the accuracy of determining the parameters of the movement of loose materials in the mixing zone. Calculations that involved this method show that the length of the particle trajectory is 2.9, and the movement time is 9 times greater than those calculated by the system of differential equations. The built and known mathematical models demonstrated the same nature of the distribution of components in the mixer. The value of the Pearson correlation coefficient between the calculated values of the coefficients of variation is 0.758. The best homogeneity is achieved by separating the flows of the mixture components and reducing the distance between their centers. The experimental study was carried out using a centrifugal mixer of continuous action with a conical rotor. Particle trajectories were constructed; it was established that the shape of the trajectory built by a discrete element method is closer to the experimental one. The results reported in this paper make it possible to predict the impact of the structural and technological parameters of the mixers of continuous action on the uniformity of the mixture
The article presents the architecture and operation principles of the system for collecting and analyzing information from strain gauges. These systems are used to determine the equipment performance for transporting a variety of materials. In particular, they are used to control the movement of bulk materials mixtures components. For such technological processes, it is fundamentally important to ensure constant flows intensity. The paper identifies three variants of sensor connection schemes, analyzes their advantages and disadvantages. It is established that the structure “one ADC – several sensors” allows to reduce equipment costs and at the same time to provide the minimum parameters influence of a transmission line on a useful sensor signal. The “one-to-one” scheme provides the connection of each sensor to its own ADC. “Circuit with multiplexer” allows to increase the number of sensors connected to one ADC. It is established that the best option in terms of reducing the interference effects on the analog signal and the cost of creating a system is the scheme “one ADC – several sensors”. The algorithm of information transfer from ADC to microcontroller (MC) is analysed. It is calculated that HX711 ADC chips provide the maximum data rate of 18.5 values/s. It is proposed to transfer data between the MC and the server using the TCP protocol because it avoids data loss and provides the necessary data transfer speed. The structure and formats of data that are transmitted from the mass sensor to the ADC, microcontroller, web server and database are proposed. The main speed, design parameters, advantages and disadvantages of wired and wireless data network between MK and the server are determined. Recommendations for the design of such a network depending on the characteristics of the premises in which the data collection system will be used have been developed.
The object of this study is the relationship between the technical characteristics of a computing system and the duration of modeling the motion of particles of granular materials by the discrete element method. The scheme of the calculation algorithm is presented; its main stages are analyzed. A 3D model of a belt feeder and a mathematical model of particle motion were developed for calculations by the discrete element method in the EDEM 2017 environment. The physical and mechanical properties of bulk material are defined; the structural and technological parameters of equipment are determined. The parameters of the algorithm and computing system are analyzed. Those parameters are defined, the change of which does not affect the accuracy of calculations but can change the volume of computing resources used. These include the number of particles of loose material, the «grid» step, and the number of processor cores. The influence of these parameters on the duration of simulation was determined using a complete factor experiment. Experimental studies have shown that for the duration of the simulation, the determining parameters are the number of particles and the number of processor cores. It was established that there is a linear relationship between the duration of the simulation and the number of particles. The regression equation is built, which makes it possible to predict the simulation time. It was also established that the software does not fully use all available computing resources; the maximum load on the processor when utilizing all available cores is 57 %. The use of RAM and disk subsystem almost did not change during simulation. The results reported here make it possible to plan the use of computing resources for research using the discrete element method and to predict the simulation time
Creation of mathematical models that allow determining the relationship between the design and technological parameters of the plate feeders and the energy consumption arising during their operation. Methodology. The work uses the classical mechanics principles, the contact interaction of solids theory and the mathematical modeling method. Findings. The paper considers the design and operation principle of a continuous plate feeder, defines its main design and technological parameters. The factors that create mechanical loads on the drive of the feeder plate are investigated. Mathematical models have been developed that make it possible to determine the moments of resistance and the power consumed by an electric motor during the equipment operation. The proposed models make it possible to determine the load on the drive in static and dynamic operation modes and take into account the design, technological parameters of the equipment and the bulk material physical and mechanical properties. The study results of the friction coefficients influence, the knife position and the force of its pressing on the plate surface, the plate rotation speed on the loads acting on the electric drive are presented. It has been found that the drive calculation is expedient for the mode in which the distance between the knife edge and the rotation axis of the plate is maximum, which corresponds to the operation at maximum load. It has been determined that a change in the feeder technological parameters (plate rotation speed, knife position) can lead to a change in the load on the electric drive by 86%, which must be taken into account when choosing a drive. Originality. Mathematical models of the continuous plate feeder operation have been developed, which make it possible to determine the relationship between the design and technological parameters of the plate feeders and energy consumption. Practical value. The results obtained make it possible to determine the load on the plate drive by the known design, technological parameters and bulk material physical and mechanical properties.
Studying the influence of continuous centrifugal mixers design features on their smoothing ability. The methods used are discrete elements, mathematical modeling and regression analysis. The paper considers five continuous centrifugal mixers designs with conical and parabolic rotors. The mixers design features are determined, allowing to change their smoothing ability. Mathematical models of the bulk materials particles movement inside each mixer have been developed based on the discrete element method. The considered mixers reaction to a step change of the key component amount is investigated. The transients parameters are calculated and the particles average residence time in the mixer is determined. It is established that the introduction of turbulizers in the mixers design increases the particles kinetic energy, which leads to a decrease in their residence time in the mixer. Moreover, the absence of a turbulizer leads to a decrease in the mixing intensity. It was also found that the most effective way to increase the mixer smoothing ability is the introduction of additional rotors. In terms of the technological and design parameters combination, the use of mixers with a conical rotor and a turbulizer is the most effective from the point of view for increasing the smoothing ability. On the discrete element method basis, the bulk materials particles movement models in continuous centrifugal mixers of five designs have been developed. The influence of the mixers design features on their smoothing ability and average mixing time is determined. The results obtained allow us to select the appropriate mixer design according to the specified requirements for smoothing ability.
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