Computer Modeling of the Joints for WGP Construction Systems

Poland is not situated in any seismic region of the earth, however there are still areas were underground mining is being conducted. In these areas, so-called 'paraseismic tremors', are very frequent phenomena. In the situation when a building examination is realized in order to define its safety, it is necessary to make a complete analysis, in which an influence of tremors should be included. To decide if a building is able to carry out any dynamic loads or not, it is necessary to compute its dynamic characteristics, i.e. natural frequencies. It is not possible using any standard techniques. After diagnosis a building in situ by an expert, computer techniques together with specialized software for dynamic, static, and strength analyses become a suitable tool. In this paper a special attention was paid to a typical twelve-store WGP (Wroclaw Great Plate) prefabricated building, concerning special type of joints. During dynamic actions these joints have a decisive influence on building's behavior. Paraseismic tremors are especially dangerous for these buildings and can be the reason of pre-failure states. It can be difficult and very expensive to prepare laboratory investigations of the part of a building or of a separate joint; therefore the computer modeling suitable to investigate behavior of such elements and whole buildings under different kinds of loads was used

Computer Modeling of the Joints for WGP Construction Systems

Poland is not situated in any seismic region of the earth, however there are still areas were underground mining is being conducted. In these areas, so-called 'paraseismic tremors', are very frequent phenomena. In the situation when a building examination is realized in order to define its safety, it is necessary to make a complete analysis, in which an influence of tremors should be included. To decide if a building is able to carry out any dynamic loads or not, it is necessary to compute its dynamic characteristics, i.e. natural frequencies. It is not possible using any standard techniques. After diagnosis a building in situ by an expert, computer techniques together with specialized software for dynamic, static, and strength analyses become a suitable tool. In this paper a special attention was paid to a typical twelve-store WGP (Wroclaw Great Plate) prefabricated building, concerning special type of joints. During dynamic actions these joints have a decisive influence on building's behavior. Paraseismic tremors are especially dangerous for these buildings and can be the reason of pre-failure states. It can be difficult and very expensive to prepare laboratory investigations of the part of a building or of a separate joint; therefore the computer modeling suitable to investigate behavior of such elements and whole buildings under different kinds of loads was used

COMPUTATIONAL SIMULATIONS FOR HOMOGENIZATION OF MASONRY STRUCTURES

In this paper proposed the application of two-parameters damage model, based on non-linear finite element approach, to the analysis of masonry panels. Masonry is treated as a homogenized material, for which the material characteristics can be defined by using homogenization technique. The masonry panels subjected to shear loading are studied by using the proposed procedure within the framework of three-dimensional analyses. The nonlinear behaviour of masonry can be modelled using concepts of damage theory. In this case an adequate damage function is defined for taking into account different response of masonry under tension and compression states. Cracking can, therefore, be interpreted as a local damage effect, defined by the evolution of known material parameters and by one or several functions which control the onset and evolution of damage. The model takes into account all the important aspects which should be considered in the nonlinear analysis of masonry structures such as the effect of stiffness degradation due to mechanical effects and the problem of objectivity of the results with respect to the finite element mesh. Finally the proposed damage model is validated with a comparison with experimental results available in the literature

Experimental study and numerical simulation of low calorific fuel combustion at different oxygen content in the oxidizer

Paper presented at the 8th International Conference on Heat Transfer, Fluid Mechanics and Thermodynamics, Mauritius, 11-13 July, 2011.This study presents results of gas fuels combustion - propane and low calorific fuel. Low calorific fuel is produced during e.g. biomass gasification, which has got of 13% H2, 4% CH4, 30% CO, 13% CO2, 40% N2. This composition is very similar to composition of fuel obtained from wood pellets gasification. Investigations have been performed at room temperature and at conditions typical for High Temperature Air Combustion, i.e. high temperature of the oxidizer (above the level of autoignition) and low oxygen content (lower than 21 % as for conventional combustion). Such environment has been created on the base of exhaust gases coming from conventional gas burner in small scale single fuel jet furnace. The temperature of the exhaust gas as well as oxygen content has been adjusted in order to achieve test conditions. Experimental results show difficulties with burning of low calorific fuel at room temperature and stable combustion at high temperature.mp201

Eksperimentalno ispitivanje i modifikacija sustava za odsis drvnih čestica na kružnoj pili

The article presents the results of experimental examination of the wood chip suction system in the existing sliding table saw before and after its modification. The studies focused on the extraction hood of the mentioned system. The methodical experimental research of the pressure distribution inside the hood during wood chip removal for the selected rotational speed of saw blades of 3500 and 6000 min-1 with a diameter of 300 mm and 450 mm were carried out. The analysis of the results allowed estimating the areas with insufficient vacuum pressure hindering the organized transport of wood chips in the sliding table saw. That pressure was the main factor influencing the decision to adjust the hood construction. To achieve the efficient performance, several changes in the hood geometry were implemented. The results obtained from the experiments were used at the stage of shape modification of the extraction hood. As a result, a new design of the chip suction system was obtained, vastly improving the chip extraction from the tool.U radu su prikazani rezultati eksperimentalnog istraživanja sustava za odsis drvnih čestica na stolnoj kružnoj pili prije njegove izmjene i nakon nje. Istraživanja su bila usmjerena na usisno ušće istraživanog sustava. Provedeno je metodološko eksperimentalno istraživanje raspodjele tlaka unutar usisnog ušća tijekom rada sustava za odsis drvnih čestica pri brzini vrtnje kružne pile od 3500 i 6000 min-1 i uz promjer lista pile od 300 i 450 mm. Analiza rezultata omogućila je procjenu područjâ s nedovoljnim podtlakom unutar kojih je onemogućen učinkovit odsis drvnih čestica na stolnoj kružnoj pili. To je i bio glavni razlog odluke o prilagodbi konstrukcije usisnog ušća. Kako bi se postigao učinkovit odsis drvnih čestica, napravljeno je nekoliko promjena u geometriji usisnog ušća. Rezultati dobiveni eksperimentalnim istraživanjem upotrijebljeni su u fazi modificiranja oblika usisnog ušća. Kao rezultat toga dobiven je novi dizajn usisnog ušća kojim je znatno poboljšan odsis drvnih čestica iz radnog prostora alata

Physical and numerical modelling of flow pattern and combustion process in pulverized fuel fired boiler

This licentiate thesis describes development of modellingtools, experimental physical modelling and numerical modellingto simulate real combustion processes for advanced industrialutility boiler before and after retrofit. The work presents extended study about formation,destruction and control of pollutants, especially NOx, whichoccur during combustion process. The main aim of this work is to improve mixing process incombustion chamber. To do this, the optimization of placementand direction of additional air and fuel nozzles, the physicalmodelling technique is used. By using that method, it ispossible to obtain qualitative information about processes,which occur in the real boiler. The numerical simulationsverify the results from physical modelling, because duringmathematical modelling quantitative informations about flow andmixing patterns, temperature field, species concentration areobtained. Two 3D cases, before and after retrofit, of pulverized fuelfired boiler at 125 MW output thermal power are simulated. Theunstructured mesh technique is also used to discretize theboiler. The number of grid was 427 656 before retrofit and 513362 after retrofit. The comparisons of results of numericalsimulation before and after retrofit are presented. The resultsfrom physical modelling and numerical simulation are alsoshown. Results present that nozzles of additional air and fuel givea considerably better mixing process, uniform temperature fieldand CO2 mass fraction. The whole combustion chamber worksalmost as a "well stirred reactor", while upper part of boilerworks as a "plug flow reactor". Differences between from measured of temperatures andpredicted temperatures are not too big, the maximum differenceis about 100 K. It seems, that calculated temperatures showgood agreement with measurement data. The results illuminate the potential of physical andnumerical modelling methods as promising tools to deal with thecomplicated combustion processes, even for practicalapplication in the industry. Keywords:air staging, fuel staging, boiler, furnace,computational fluid dynamics, numerical simulation, pollutants,physical modeling, pulverized fuel combustion.NR 2014080

Modeling of low calorific gas burning in a deficient oxygen environment and high-temperature oxidizer

It is planned to carry out a comprehensive experimental and theoretical study on the high temperature of low calorific gas combustion with oxygen-deficient oxidizers. The experimental research will be performed using the experimental facility with a combustion chamber. The oxygen concentration in combustion oxidizers will be varied from 21% by volume (normal) air to 2%. The test combustion chamber will be fed with propane or methane as the reference fuel, then with low calorific fuels as test gases obtained by mixing various combustible components, e.g. H2, CH4, CO, and neutral gases, e.g. N2, CO2. Gaseous fuels prepared in this way will be burned in the atmosphere of a deficient oxidizer with a temperature changing from 800 °C to 1100 °C. Oxidizers will be heated up to a certain temperature using two methods: by flue gas heat exchanger and kanthal rod electric preheater. Different burner geometry will be used. The burner will be equipped with annular swirl vanes for co-axial or under different angles, fuel, and oxidizers flow to have a high swirl number achieved by flow aerodynamics and mixing. Experimental data will be verified with numerical simulations with the use of ANSYS CFD Fluent code

Analysis of Triboelectrostatic Separation Process of Mixed Poly(ethylene terephthalate) and High-Density Polyethylene

The aim of this study was to investigate and analyze the separation process of poly (ethylene terephthalate) and high-density polyethylene mixture. The research studied the influence of parameters of tribocharging and separation processes on the quality of separation. The research was carried out using a developed test stand consisting of a test tribocharger and a dedicated drum-type electrostatic separator. Both the separator and the tribocharger have been designed as automated test benches to assess the quality of plastic separation. In order to assess the quality of electrostatic separation of plastics, an original method based on the use of a dedicated vision system was used. The research was conducted in two stages. Firstly, the influence of the tribocharging process parameters on the efficiency of the process, i.e., the charge collected, was investigated. The next stage of the research was focused on the analysis of the influence of the separation process parameters on its effectiveness. The obtained results were presented and discussed. On the basis of the conducted research, the parameters of the tribocharging and separation processes affecting their effectiveness were determined