Jan Nečas

Optimization of Drive Unit through Load Measurement

The basis is a device that contains tension sensor. The output of tension sensor is associated with the input control unit. The tension sensor is connected between the two loads. The sensing signal is processed using a PC measuring card with special software. The resulting device will be part of trains. Data sensing by this device will be transmitted from the PC to the control unit.

Use of DEM in the Determination of Friction Parameters on a Physical Comparative Model of a Vertical Screw Conveyor

This article deals with the use of DEM in the application of a screw conveyor for bulk materials. Utilisation of DEM anticipates input parameters which can be obtained only by experimental and laboratory activity in the area of the transport and properties of bulk materials. These concern mainly friction parameters describing flow properties on the transport equipment. Without this knowledge, the use of DEM is limited. With knowledge of the mechanical and physical properties of bulk materials and contact geometries, the use of DEM applies to the simulation of the real behaviour of the conveyed material. This state can only be achieved by verification of the concordance of the simulation and real state, alternatively by calibration. Calibration must be performed on the basis of ranges of input values ascertained in the laboratory environment. After that, it is necessary to obtain the output parameters by an experiment from the DEM-simulation such as particle velocity during transport on the vertical screw conveyor. The same method is used when it is necessary to obtain values from the actual equipment by the PIV method on the basis of which the DEM model will be optimized.

Simulation of material flow through a sample divider

The prerequisite for a modern approach to innovative procedures of the development of current or even newly created equipment for the transport of particulate materials is the utilization of simulation methods, such as the Discrete Element Method (DEM). This article focuses on the basic, or initial, validation of movement of material through the sample divider. The mechanical-physical properties of brown coal were measured. Based on these parameters the preliminary input values for EDEM Academic were selected, and a simulation of the dividing process was run. The key monitored parameters included density and friction coefficient. Experiments on a realistic model of the equipment were performed and assessed. The total weights of brown coal at the exit from the divider were determined for a specific speed of the divider. The aim of this task was to simulate the realistically determined weight division of the brown coal sample. The result from the DEM was compared with the results of measurement on a realistic model.

VALIDATION OF MOVEMENT OVER A BELT CONVEYOR DRUM

This paper presents the use of new modern methods for the research of movement of material on a belt conveyor. One of the innovative methods is Particle Image Velocimetry (PIV), which was used to scan and assess the two-dimensional vector field of speed of particles on the belt conveyor. Outputs from PIV were compared to simulations of the same transport process. These simulations were performed using the Discrete Element Method (DEM). Four transport speeds of material were assessed for a real and simulative belt conveyor model. Software tracking of particle movement was used to determine and compare the trajectories of paths of particles leaving the belt conveyor drum. Validation of the DEM simulation of material movement over a belt conveyor drum using PIV provided acceptable results in the area of particle speed fields. Comparison of the particle path trajectory corresponds to the preliminary hypothesis which leads to calibration of the DEM simulation. The results and assessment of this paper were created based on validation.