The article presents the problems of determining the mass efficiency of a rotary feeder depending on the selection of design parameters of the device, such as outer diameter, number of blades and ...rotational speed of the rotor. The hitherto theoretical methods of calculating the feeder efficiency were presented, as well as a new method of determining the device operation parameters was proposed. For this purpose, the numerical Discrete Element Method was used, which allowed simulating the transport of limestone powder in a cell feeder with various design variants. The results of the tests showed that the above design parameters affect the instantaneous efficiency of the feeder and thus impact the distribution of the dosed material during the operation of the device. Depending on the design solution, the simulation results gave information on the fill factor of the feeders. The study showed a significant potential of DEM simulation in the design of circular feeders intended for dosing bulk materials.
The paper discusses the designing process of screw conveyors, with regard to the determination of the exploitation parameters of such devices with the use of the Discrete Element
Method (DEM). The ...influence of the chosen model input parameters on the results of the
simulations was examined. The key parameters which determine the exploitation characteristics of a screw conveyor were identified as follows: the size of a DEM particle, coefficients
of internal and external friction. Experimental measurements of the laboratory screw conveyor provided the actual exploitation characteristics of a device used for the transportation
of a limestone powder. The comparison of the results of the simulations and experiments
gave satisfactory results. For this reason, DEM simulations were identified as an effective
tool for determining and optimization of the construction and exploitation parameters of the
screw conveyors
The paper describes the problem of designing screw conveyors in terms of determining their
exploitation characteristics. Based on the actual values of mass efficiency and power demand obtained in a ...laboratory experiment, the theoretical design methods and the numerical
discrete element method model results were verified. The obtained results have shown that
the currently used theoretical methods underestimate the mass efficiency and power demand
compared to experiments when typical values of filling rate coefficient and progress resistance coefficient are used. It was also shown that the results of DEM simulations are in good
agreement with the experiments in terms of mass efficiency and power demand. Based on
the exploitation characteristics determined in DEM simulations for different constructions
of the screw and different rotational speeds, multi-objective optimization of the exploitation
parameters of the screw was performed in order to minimize the power demand of a screw
conveyor and simultaneously maximize its mass efficiency. The optimization results showed
that it is possible to find such construction and the rotational speed that will maximize the
mass efficiency of the conveyor and keep the power demand low, reducing the exploitation
costs of the device.
Analytical methods for calculations of the transport machinery are often insufficient especially when untypical granular materials are considered. Discrete Element Method (DEM) is a very useful ...numerical tool supporting designing and optimization of the
transport equipment. However, to obtain reliable DEM simulation results an accurate set of input parameters values is needed.
The most common calibration approach is to make use of a procedure where laboratory tests are performed and then the same
experiments are numerically replicated in DEM. The article presents calibration of the DEM input parameters on the example of
perlite D18-DN Based on the performed calibration, the model of perlite transport in a screw conveyor has been shown.
We present results of studies of extremely short acoustic pulses as recorded by an artificial ear in an anechoic chamber. Two types of ultrashort acoustic pulses have been used: cosine signal with ...the Gaussian envelope and the Gaussian envelope itself. All pulses had duration times between 0.14 ms and 27.21 ms. The recorded spectra exhibited a maximum whose position shifted towards higher frequencies with decreasing duration time. This corroborates the concept of the effective pitch sensation produced by pulses beyond the uncertainty principle. Two mathematical models have been used to reveal the reaction of the basilar membrane to the pulses, and their distortions by electronic devices.
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