Main the Oretical Provisions of Grain Material Separation in Air Channels with Unequal Air Flow Speed

2020 ◽  
pp. 122-133
Author(s):  
Serhii Stepanenko ◽  
◽  
Boris Kotov ◽  
Keyword(s):  
Initial Conditions ◽  
Flow Speed ◽  
Material Point ◽  
Friction Forces ◽  
Air Stream ◽  
Air Resistance ◽  
Material Separation ◽  
Round Section ◽  
Air Channels ◽  
Rational Shape

The article considers the increase of efficiency of grain materials separation in pneumatic vertical channels by determining the rational shape and parameters of material supply, as well as the geometric shape of the pneumatic channel and options for separation into fractions. Regularities of change of trajectory and speed of movement of material in pneumatic vertical channels of round section with the lower unloading of material are received. The regularities of particle motion in the form of a material point were determined taking into account air resistance forces, friction forces, Magnus and Zhukovsky forces, material moisture and density based on a theoretical study of grain fractionation in pneumatic vertical channels. Using the proposed dependences for the design of air separators, it is possible to determine the initial rate of introduction and the direction of entry of grains into the air stream, which are the initial conditions for determining the trajectory of material in air channels with lower material discharge.

Particle motion with air resistance

2012 ◽  
Vol 8 (1) ◽  
pp. 1-15
Author(s):  
Gy. Sitkei
Keyword(s):  
Basic Equation ◽  
Initial Conditions ◽  
Equation Of Motion ◽  
Terminal Velocity ◽  
Dimensionless Form ◽  
Wood Industry ◽  
Acceptable Error ◽  
General Validity ◽  
Practical Applications ◽  
Air Resistance

Motion of particles with air resistance (e.g. horizontal and inclined throwing) plays an important role in many technological processes in agriculture, wood industry and several other fields. Although, the basic equation of motion of this problem is well known, however, the solutions for practical applications are not sufficient. In this article working diagrams were developed for quick estimation of the throwing distance and the terminal velocity. Approximate solution procedures are presented in closed form with acceptable error. The working diagrams provide with arbitrary initial conditions in dimensionless form of general validity.

scholarly journals MATHEMATICAL MODELING OF PROCESSES OF SEPARATION OF COMPONENTS OF GRAIN MATERIAL IN THE COMBINED VIBRATION-AIR SEPARATOR

2020 ◽  
pp. 51-59
Author(s):  
Sergey Stepanenko ◽  
Borys Kotov
Keyword(s):  
Mathematical Modeling ◽  
Equations Of Motion ◽  
Air Flow ◽  
Flow Speed ◽  
Material Point ◽  
Experiment Planning ◽  
Theoretical Studies ◽  
Fluidized Layer ◽  
Aerodynamic Properties ◽  
Air Separator

Development of a mathematical model and calculated analytical dependencies for determining the trajectories and parameters of grain movement in a vibro-fluidized layer of grain material components under the action of a pulsating air flow. They are based on the methods of deterministic mathematical modeling and theoretical mechanics based on the equations of motion of a material point at a variable air flow speed and the action of a pulsating air flow. Theoretical studies were carried out using the methods of mathematical analysis and modeling. The research results were processed using elements of the theory of probability and mathematical statistics using software packages; to determine the rational parameters of the process, the method of statistical experiment planning was used. A mathematical description of the motion of the grain material particles in a combined vibration-air separator under the action of a pulsating air flow of variable speed is given. The trajectories of motion of particles with different sizes are obtained. The obtained equation of motion of a particle under the influence of a pulsating air flow makes it possible to determine the dependence of the speed of movement of the material in a vibro-fluidized layer of grain material on a number of factors: the geometric parameters of the sieve-free sieve, the feed angle of the material, the initial kinematic mode of the material, the index of the kinematic mode of the sieve-free sieve, as well as the coefficient of windage of the grain. On the basis of theoretical studies, the possibility of separating particles of grain material into fractions according to aerodynamic properties with vibropneumatic loading of grain into the channel has been determined. The use of a pulsating air flow as a separating carrier, and taking into account the deflecting forces, made it possible to significantly increase the splitting of the trajectories and the criterion for dividing the grain into fractions.

scholarly journals DEMONSTRATION TASKS OF LIQUID AND GAS PROPERTIES AND THEIR RATIONALE SENSE

2010 ◽  
Vol 7 (1) ◽  
pp. 29-37
Author(s):  
Violeta Šlekienė ◽  
Loreta Ragulienė
Keyword(s):  
Gas Flow ◽  
Liquid Surface ◽  
Flow Speed ◽  
Pressure Reduction ◽  
Physics Teaching ◽  
Liquid Surface Tension ◽  
Air Stream ◽  
Logical Sense ◽  
Physical Phenomena ◽  
Gas Properties

The article reveals the importance of demonstration tasks in physics teaching in secondary schools. Four demonstration of the liquid and gas properties are presented and analyzed. They are: Pressure dependence of gas flow speed; Pressure reduction in air-stream; Wing lift; Liquid surface tension. Reasoning schemes for giving a logical sense to these physics demo tasks are developed. The proposed reasoning schemes reach to activate students' thinking, understanding the demonstrations during the observed physical phenomena, i.e. help students to: understand the nature of the demo task, determine cause - effect relationships and dependencies, compare conditions and findings, summarize the results, do conclusions. Such using of demonstration tasks is useful to both of teacher and pupil: teacher controls the content of teaching and a learning of pupils, pupils - are focused to self-activities, encouraged to think, analyze, summarize and do conclusions. Key words: physics teaching, demonstration task, liquid and gas properties, reasoning schemes.

scholarly journals Hybrid Simulation of Solar-Wind-Like Turbulence

Solar Physics ◽  
2019 ◽  
Vol 294 (11) ◽  
Author(s):  
D. Aaron Roberts ◽  
Leon Ofman
Keyword(s):  
Magnetic Field ◽  
Solar Wind ◽  
High Speed ◽  
Radial Flow ◽  
Initial Conditions ◽  
Thermal Fluctuations ◽  
Flow Speed ◽  
Initial State ◽  
Simplifying Assumptions ◽  
The Magnetic Field

Abstract We present 2.5D hybrid simulations of the spectral and thermodynamic evolution of an initial state of magnetic field and plasma variables that in many ways represents solar wind fluctuations. In accordance with Helios near-Sun high-speed stream observations, we start with Alfvénic fluctuations along a mean magnetic field in which the fluctuations in the magnitude of the magnetic field are minimized. Since fluctuations in the radial flow speed are the dominant free energy in the observed fluctuations, we include a field-aligned $v_{\|}(k_{\perp })$v∥(k⊥) with an $k^{ -1}$k−1 spectrum of velocity fluctuations to drive the turbulent evolution. The flow rapidly distorts the Alfvénic fluctuations, yielding spectra (determined by spacecraft-like cuts) transverse to the field that become comparable to the $k_{\|}$k∥ fluctuations, as in spacecraft observations. The initial near constancy of the magnetic field is lost during the evolution; we show this also takes place observationally. We find some evolution in the anisotropy of the thermal fluctuations, consistent with expectations based on Helios data. We present 2D spectra of the fluctuations, showing the evolution of the power spectrum and cross-helicity. Despite simplifying assumptions, many aspects of simulations and observations agree. The greatly faster evolution in the simulations is at least in part due to the small scales being simulated, but also to the non-equilibrium initial conditions and the relatively low overall Alfvénicity of the initial fluctuations.

Three-dimensional material point method modeling of runout behavior of the Hongshiyan landslide

2019 ◽  
Vol 56 (9) ◽  
pp. 1318-1337 ◽  
Author(s):  
Xiaorong Xu ◽  
Feng Jin ◽  
Qicheng Sun ◽  
Kenichi Soga ◽  
Gordon G.D. Zhou
Keyword(s):  
Progressive Failure ◽  
Three Dimensional ◽  
Material Point Method ◽  
Numerical Approach ◽  
Flow Speed ◽  
Material Point ◽  
Point Method ◽  
Field Scale ◽  
Rate Dependent ◽  
Depth Direction

This study presents a field-scale simulation of the Hongshiyan landslide in China. It uses an advanced numerical approach (material point method (MPM)) and a constitutive model (the Drucker–Prager model + μ(I) rheological relation) for the three-dimensional (3D) simulation. The performance of the developed MPM model is validated with laboratory-scale experimental data on granular collapse before being applied to field-scale analyses. ArcGIS data are used to create a 3D MPM model of the soil body with complicated geometry. Although the developed model can describe the multiple phases of granular flow, it focuses on the runout behavior of the landslide in this work. The landslide is assumed to have occurred suddenly due to an earthquake, and global sudden failure rather than progressive failure is modeled. The MPM simulation results match reasonably well with the measured post-earthquake topography (e.g., deposit height of about 120 m and stretch length of about 900 m in the river) and landslide duration of about 1 min. The velocity of the sliding mass increases rapidly during flow, especially in the first 20 s. The velocity profiles along the depth direction at different locations of the sliding body exhibit an exponential distribution similar to that of a Bagnold-type profile, indicating that the sliding body is fully mobilized. The rate-dependent dissipation parameter β used in the model significantly influences the runout behavior (e.g., flow speed, velocity distribution, and deposit shape).

A Continuum Model for Dynamic Tensile Microfracture and Fragmentation

1985 ◽  
Vol 52 (3) ◽  
pp. 593-600 ◽  
Author(s):  
L. Seaman ◽  
D. R. Curran ◽  
W. J. Murri
Keyword(s):  
Continuum Model ◽  
Crack Density ◽  
Volume Growth ◽  
Material Point ◽  
Detailed Simulation ◽  
Elastoplastic Materials ◽  
Material Separation ◽  
Dependent Growth ◽  
Stress Dependent ◽  
Fracture Processes

A continuum model for dynamic tensile cleavage fracture and fragmentation has been developed for detailed simulation of brittle fracture processes in elastoplastic materials. The model includes processes for nucleation of microcracks, stress-dependent growth, coalescence and fragmentation, and stress relaxation caused by the developing damage. Fracturing is characterized by a crack density with a distribution of sizes at each material point. The model extends previous work by treating more completely full material separation and stress-free volume growth, as well as multiple loadings, unloadings, and recompaction, and by describing the damage in greater microscopic detail.

scholarly journals Analytical construction of the projectile motion trajectory in midair

MOMENTO ◽  
2021 ◽  
pp. 79-96
Author(s):  
Peter Chudinov ◽  
Vladimir Eltyshev ◽  
Yuri Barykin
Keyword(s):  
Analytical Solutions ◽  
Initial Conditions ◽  
Resistance Force ◽  
Tennis Ball ◽  
Projectile Motion ◽  
Classic Problem ◽  
Analytical Construction ◽  
Air Resistance ◽  
Wide Range ◽  
Large Period

A classic problem of the motion of a projectile thrown at an angle to the horizon is studied. Air resistance force is taken into account with the use of the quadratic resistance law. An analytic approach is mainly applied for the investigation. Equations of the projectile motion are solved analytically for an arbitrarily large period of time. The constructed analytical solutions are universal, that is, they can be used for any initial conditions of throwing. As a limit case of motion, the vertical asymptote formula is obtained.  The value of the vertical asymptote is calculated directly from the initial conditions of motion. There is no need to study the problem numerically. The found analytical solutions are highly accurate over a wide range of parameters. The motion of a baseball, a tennis ball, and a shuttlecock of badminton are presented as examples.

scholarly journals Design of an Optimal Fuzzy Controller of an Under-Actuated Manipulator Based on Teaching-Learning-Based Optimization

2019 ◽  
Vol 13 (3) ◽  
pp. 166-172
Author(s):  
Mohammad Javad Mahmoodabadi ◽  
Amineh Yazdizadeh Baghini
Keyword(s):  
Control Method ◽  
Fuzzy Controller ◽  
Initial Conditions ◽  
Absolute Error ◽  
State Variables ◽  
Friction Forces ◽  
Time Integral ◽  
Tlbo Algorithm ◽  
Teaching Learning Based Optimization ◽  
Teaching Learning

Abstract In this paper, an optimal fuzzy controller based on the Teaching-Learning-Based Optimization (TLBO) algorithm has been presented for the stabilization of a two-link planar horizontal under-actuated manipulator with two revolute (2R) joints. For the considered fuzzy control method, a singleton fuzzifier, a centre average defuzzifier and a product inference engine have been used. The TLBO algorithm has been implemented for searching the optimum parameters of the fuzzy controller with consideration of time integral of the absolute error of the state variables as the objective function. The proposed control method has been utilized for the 2R under-actuated manipulator with the second passive joint wherein the model moves in the horizontal plane and friction forces have been considered. Simulation results of the offered control method have been illustrated for the stabilization of the considered robot system. Moreover, for different initial conditions, the effectiveness and the robustness of the mentioned strategy have been challenged.

METHOD OF FINDING LOSSES IN THE THROTTLE WINDING AS A RESULT OF THE SKIN EFFECT AND THE PROXIMITY EFFECT

2022 ◽  
pp. 87-94
Author(s):  
А.А. Моисеенко ◽  
С.М. Фёдоров
Keyword(s):  
Electromagnetic Fields ◽  
Initial Conditions ◽  
Dimensional Space ◽  
Variable Number ◽  
Distributed Software ◽  
Good Convergence ◽  
Analytical Formulas ◽  
Round Section ◽  
Winding Wire ◽  
Comparison Of The Results

Представлен метод использования расчетных методик и моделирования магнитных полей в двухмерном пространстве для нахождения высокочастотных потерь в обмотке моточных изделий, таких как дроссель или трансформатор. Была проведена работа по анализу литературы по данной теме, а также поднят вопрос оптимизации и адаптации аналитических формул для случая использования проводников круглого сечения и намотки, имеющей неоднородное распределение слоев в окне сердечника. Был также поднят вопрос об аналитическом нахождении длины обмоточного провода намотки с различным количеством слоев и переменного количества используемых при этом витков. Для проведения автоматизации расчета с помощью формул был написан скрипт, строящий зависимость сопротивления переменному току относительно частоты, используя аналитические формулы. Была написана программа для автоматической постановки начальных условий и граничных значений параметров моделирования, процесса самого моделирования электромагнитных полей, анализа полученных данных, а также формирования массива для построения графика полученной при этом зависимости сопротивления от частоты. В данном методе используется свободно распространяемое программное обеспечение как для математических расчетов, так и моделирования электромагнитных полей. Итогом данной работы стало сравнение полученных результатов, которые показали хорошую сходимость и преемственность этапов данного метода Here we present a method for using computational methods and modeling magnetic fields in two-dimensional space to find high-frequency losses in the winding of winding products, such as a choke or transformer. We analyzed the literature on this topic, as well as the issue of optimization and adaptation of analytical formulas for the case of using round-section conductors and winding having a non-uniform distribution of layers in the core window. We discussed the analytical finding of the length of the winding wire of the winding with a different number of layers and a variable number of turns used in this case. To automate the calculation using formulas, we wrote a script that builds the dependence of the resistance to alternating current relative to the frequency using analytical formulas. In addition, we wrote a program for automatically setting the initial conditions and boundary values of the modeling parameters, the process of modeling electromagnetic fields itself, analyzing the data obtained, as well as forming an array for plotting the resulting dependence of resistance on frequency. This method uses freely distributed software for both mathematical calculations and modeling of electromagnetic fields. The result of this work was a comparison of the results obtained, which showed good convergence and continuity of the stages of this method

Flutter Amplitude Saturation by Nonlinear Friction Forces: Reduced Model Validation

2014 ◽  
Author(s):  
Carlos Martel ◽  
Roque Corral ◽  
Rahul Ivaturi
Keyword(s):  
Initial Conditions ◽  
Oscillation Amplitude ◽  
Reduced Model ◽  
Limit Cycle Oscillation ◽  
Nonlinear Friction ◽  
Disk Model ◽  
Friction Forces ◽  
Elastic Oscillation ◽  
Time Modulation ◽  
Bladed Disk

The computation of the final, friction saturated Limit Cycle Oscillation amplitude of an aerodynamically unstable bladeddisk in a realistic configuration is a formidable numerical task. In spite of the large numerical cost and complexity of the simulations, the output of the system is not that complex: it typically consists of an aeroelastically unstable traveling wave (TW), which oscillates at the elastic modal frequency and exhibits a modulation in a much longer time scale. This slow time modulation over the purely elastic oscillation is due to both, the small aerodynamic effects and the small nonlinear friction forces. The correct computation of these two small effects is crucial to determine the final amplitude of the flutter vibration, which basically results from its balance. In this work we apply asymptotic techniques to consistently derive, from a bladed-disk model, a reduced order model that gives only the time evolution on the slow modulation, filtering out the fast elastic oscillation. This reduced model is numerically integrated with very low CPU cost, and we quantitatively compare its results with those from the bladed-disk model. The analysis of the friction saturation of the flutter instability also allows us to conclude: (i) that the final states are always nonlinearly saturated TW, (ii) that, depending on the initial conditions, there are several different nonlinear TWs that can end up being a final state, and (iii) that the possible final TWs are only the more flutter prone ones.

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