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Wpływ lepkości osnowy na rozpływ i zjawisko sedymentacji w samolejnych betonach ogniotrwałych

Majchrowicz I.

Szkło i Ceramika

2012

R. 63, nr 6

30—34

Zdolność betonów samolejnych do płynięcia pod wpływem działania siły grawitacji zależy od wielu czynników, m.in. od składu ziarnowego, ilości wody oraz od rodzaju i ilości upłynniacza. W opracowywaniu betonów samolejnych należy również uwzględnić własności reologiczne osnowy (wielkość cząstek <45 μm)- Lepkość osnowy powinna być niska na tyle, aby zapewnić dostateczne płynięcie betonu, ale jednocześnie na tyle wysoka, aby zapobiec sedymentacji kruszywa. Celem niniejszej pracy było określenie związku pomiędzy lepkością osnowy a rozpływem i zjawiskiem sedymentacji w betonach samolejnych. Badano możliwość zastosowania prawa Stokes'a w prognozowaniu segregacji kruszywa. Wyniki obliczeń porównano z rezultatami doświadczeń.

The essence of the self-flow castables is their ability to flow under the gravity force. This feature depends on many factors like, particle size distribution, amount of water as well as type and amount of dispersant. In designing of self-flowing castables, the rheological properties of matrix (particle size <45 μm) also must be taken into account. The viscosity of matrix should be low enough to ensure self-flowing of castables, but high enough to prevent sedimentation. In this work, usefulness of Stokes law in predicting segregation of coarse particles in the self-flow castables was investigated. Calculations were compared with experimental results. Additionally, the effect of matrix viscosity on the free-flow value of castables was determined.

Simulation of liquid dynamics in a cryogenic mobile vessels

Lisowski E., Domagała M.

Archives of Foundry Engineering

2010

Vol. 10, iss. 3 spec.

77--80

Technical gases becomes liquid in extremely low temperature ranging minus 200 °C and very high pressure what makes that transportation devices have to perform very strict requirement. Presented paper shows selected aspect of simulation of liquefied gas sloshing in aspect of requirements that mobile vessels have to fulfill. Mobile vessel which is the object of simulation is a two shell tank with vacuum and layer insulation between shells adapted to 20 ft container. It is assigned for see, railway and road transport and have to follow all of requirements for such transportation systems. Requirements for such tank are enclosed in standard ISO 1496-3 which deals with freight containers and standard EN13530-2 that describes vacuum, cryogenic vessels. The standards EN13530-2 defines that vessels which are to be filled equal or less than 80% should be fitted with surge plates to provide vessel stability and limit dynamic loads. Additionally surge plates area has to be at least 70% of cross section of the vessel and volume between surge plates shall be not higher than 7.5 m3. Structure of the vessel as well as the surge plate should resist of longitudinal acceleration of 2g. Additionally surge plates shall resists stresses caused by pressure distributed across the area of surge plate and the pressure shall be calculated as mass of liquid between plates and acceleration 2g. In this paper is presented way of simulation of dynamic behavior of liquefied Argon on vessel structure. A numerical methods like Computational Fluid Dynamics (CFD) and Finite Element Analysis (FEA) were used for this purpose. Combination of both tools allowed to get pick value of dynamic pressure that arising during acceleration of 2g, which was assumed is 0.2 s and investigate resistance of vessel and container structure. Presented approach is called Fluid – Structure Interaction simulation. In CFD simulation was used Ansys CFX code, while for FEA calculations Pro/Mechanica package.