8 research outputs found
Numerical Simulation of Like and Unlike Impinging Jets
No full text[EN] In the present study, using the open source OpenFOAM code, a numerical simulation is performed taking the adaptive
mesh refinement (AMR) technique during solution. Formation of liquid sheet after the impact of two identical cylindrical
jets at various conditions is studied. Since the flow pattern depends upon the Reynolds and Weber numbers, numerical
tests are conducted at a variety of flow velocities and Reynolds numbers to demonstrate the effect of these parameters
on the sheet formation. It is then concluded that at various conditions, different instabilities occur in the flow; hence,
different sheet formations a flow patterns happen.
In this study, impact of two dissimilar cylindrical fluid jets is successfully simulated for the first time in literature. Actually,
water and oil jets are taken into account and their impact behavior is studied. In the presence of the surrounding air, an
unstable sheet will form after impact due to the high injection speed of the jets. As depicted in the results, since the inertia
and other physical characteristics of the two fluids are dissimilar, different phases are more intensely diffused.Dolatkhahi, H.; Oliaee, G.; Kebriaee, A. (2017). Numerical Simulation of Like and Unlike Impinging Jets. En Ilass Europe. 28th european conference on Liquid Atomization and Spray Systems. Editorial Universitat Politècnica de València. 265-272. https://doi.org/10.4995/ILASS2017.2017.4865OCS26527
A Comprehensive Predictive Model to Predict Droplets Size Distribution in Pressure Swirl Atomizer
No full text[EN] A predictive model is proposed to determine the droplet size and velocity distribution at the beginning of the
secondary breakup. Liquid bulk is subjected to three stages of atomization including flow inside the injector, primary
atomization, and secondary atomization to change a spray. The flow inside pressure swirl injector consisting an
axial air core is a strongly complex two phase flow studied by highly precision coupled level set and volume of fluid
method (CLSVOF). Subsequently, breakup lengths, interface deformation, as well as the most unstable frequency
mode are calculated by nonlinear stability theory applied to emanating liquid sheet. Application of maximum entropy
principle (MEP) is the final stage to predict size and velocity distribution of spray droplets. Based on liquid sheet
breakup and conservative equations involving continuity, momentum, and energy, Newton-Raphson method is used
to solve MEP equations. The proposed model has no dependency on empirical data in comparison with the usual
past researches. The predicted results are shown to be in good agreement with the experimental findings related
to performance characteristics and droplets size.Jafari, S.; Kebriaee, A.; Sohrabi, S. (2017). A Comprehensive Predictive Model to Predict Droplets Size Distribution in Pressure Swirl Atomizer. En Ilass Europe. 28th european conference on Liquid Atomization and Spray Systems. Editorial Universitat Politècnica de València. 628-635. https://doi.org/10.4995/ILASS2017.2017.4845OCS62863
Qualitative Analysis of Spray Characteristics of Impinging Jets Using A Gelled Non-Newtonian Propellant Simulant: Paper 159
No full textA model for determining thermodynamic and transport properties of electric arc plasmas at elevated pressures and temperatures and its validations
No full textCalculation of thermodynamic properties and air transport properties at 19 pressures and a temperature range from 300 to 100,000 K and calculation of argon properties at atmospheric pressure and a temperature range from 300 to 30,000 K. A self-consistent approach for the thermodynamic properties and the higher-order approximation of the Chapman–Enskog method for the transport properties have been used. Debye–Hukel corrections have been considered in the thermodynamic properties. These transport properties under local thermodynamic equilibrium conditions are placed inside the magnetohydrodynamic equations to simulate two models argon arc and air arc, at atmospheric pressure. This self-consistent model is effective for analysing the physical behaviour of the high-intensity electrical discharge at atmospheric pressure. The simulation results show that a complete local chemical equilibrium occurs when the properties of the plasma reach more than 100,000 K at each pressure. Air and argon transport properties have been fitted with Gaussian and Sigmoid functions and over 58 species have been considered in the air composition
Petrography, Geochemistry and Proposed Genesis of Ordovician Oolitic Iron Formation Members of the Lashkarak Formation, Eastern Alborz
No full textIntroduction
Oolitic iron formations are sedimentary rocks with >5 vol.% oolites and >15 wt.% iron, corresponding to 21.4 wt.% Fe2O3 (Young, 1989; Petranek and Van Houten, 1997; Mucke and Farshad, 2005). In Iran, new iron oolite-bearing members have been identified in the Lashkarak Formation (lower-middle Ordovician) in the Abarsej, Dehmola and Simehkuh sections, eastern Alborz (Ghobadi Pour et al., 2011). At present, the mineralogy and geochemistry of these members are not known. Consequently, research reported here was conducted to reveal the mineralogical and geochemical characteristics of Ordovician oolitic iron formationmembers and to discuss their genesis and economic importance.
Materials and Analyses
Field geology and sampling was carried out to collect 25 samples from the ooliticiron formation members in the Abarsej, Dehmola and Simehkuh section in eastern Alborz. Samples were prepared for polished-thin sections (n=10), XRD analysis (n=15). Whole-rock chemical analysis (n=15) by XRF for major elements and by ICP-ES for trace elements was performed by laboratories at the SarCheshmeh copper mine complex, Kerman, Iran. One sample was analyzed by SEM at the Wales Museum, UK.
Results
Microscopic studies show that the oolitic iron formation members are hosted by carbonate argillite rocks. They are mainly composed of oolites rather than pisoliths (small bodies somewhat larger and more irregular than oolites), whereas oolites have mainly ellipsoidal forms and locally spherical shapes. Most (6) oolites show banding with a central core. Simple oolites without a core are scarce. Mineralogically, oolites are mainly chamositic and hematitic in composition; goethite, pyrite and glauconite occur in traces and siderite is absent. Quartz, calcite and zircon are accessory minerals which are present in the groundmass. Geochemically, TFeO % of the oolitic iron formation horizons ranges from 8 to 48 % with an average of 21%. The CaO content ranges from 2 to 37% and SiO2 from 11 to 37 %. Based on TFeO % content, oolitic iron formation horizons are divided into two geochemical groups: 1: Low-grade iron formations ( the Abarsej section) (8) with TFeO
Discussion
Mineralogical characteristics combined with geochemical data show that anomalous values of Fe in studied carbonate argillite formations with respect to common sedimentary rocks are related to the abundance of iron-bearing oolites as oxides such as hematite and goethite, and the clay mineral chamosite. Based on Fe, Mg and Ca concentrations, oolitic iron formations can be divided into low-grade and high-grade iron formations. The former is characterized by chamosite and calcite, whereas the latter consists ofhematite and calcite. This research, along with available paleo-geographic and sedimentological information suggests that the iron for the formation of iron oolites was available from normal sea water and Fe could be carried as clastic particles along with clays or coating of clay particles derived from weathering and erosion of shales from adjacent land. High contents of K and Si in oolitic iron horizons, the presence of detrital zircon, quartz and clay minerals within oolites and also in the matrix of these rocks confirm the proposed model and show the important role of Fe-bearing clay minerals in the genesis of the primary chamositic oolites in an environment with pH=5-9 and medium-weak redox conditions (Maynard, 1983; Maynard, 1986). The abundance of hematite relative to goethite in the Fe-oolites, dense and elliptical oolites as well as the frequent occurrence of calcite veinlets cutting oolite beds has been attributed to diagenetic processes and the modification of chamosite and goethite to hematite. Our findings indicate that the studied members can be classified as low-grade oolitic iron formation (average 21 wt.% Fe) which do not have economic importance at present.
Acknowledgements
This study is part of the senior author's M.Sc thesis at Golestan University, Gorgan, Iran. Logistical and financial support was provided by the Research Grant to senior author. We are grateful to SarCheshmeh Copper Complex for XRF analyses and IMPERC for XRD measurements. We gratefully acknowledge Dr. Ghobadipour for SEM analysis in National Museum of Wales, Great Britain.
References
Ghobadi Pour, M., Popov, L.E., Kebriaee-Zadeh, M.R. and Baars C.H., 2011. Middle Ordovician (Darriwilian) Brachiopods associated with the Neseuretus bio-facies, Eastern Alborz Mountains, Iran. Memoirs of the Association of Australasian Palaeontologists, 42(3): 263-283.
Maynard, J.B., 1983. Geochemistry of sedimentary ore deposits. Springer-Verlag, NewYork, 382 pp.
Maynard, J.B., 1986. Geochemistry of oolitic iron ores, an electron microprobe study. Economic Geology, 81(8): 1473-1483.
Mucke, A.T. and Farshad, F., 2005. Whole-rock and mineralogical composition of Phanerozoic ooidal ironstones: Comparison and differentiation of types and subtypes. Ore Geology Reviews, 26(2): 227-262.
Petranek, J. and Van Houton, F.B., 1997. Phanerozoic ooidal ironstone. Czech Geological Survey, Special Papers 7: 70 pp.
Young, T.P., 1989. Eustatically controlled ooidal ironstone deposition: facies relationships of the Ordovician open-shelf ironstones of Western Europe. In: T.P. Young and W.E.G. Taylor (Editors), Phanerozoic Ironstones. Geological Society of London, Special Publication, 46(1): 51–64.
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