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Abstract

The article presents a numerical model of a U-ventilated longwall, taking into account detailed elements such as arch yielding support, roof supports and shearer. What distinguishes it from previous models is the mapping of adjacent goafs. This model considers the current state of knowledge regarding spatial height distribution, porosity and permeability of goafs. Airflow calculations were carried out using the selected turbulence models to select appropriate numerical methods for the model. Obtained results show possibilities of conducting extensive numerical calculations for the flow problems in the mine environment, taking into account more complex descriptions and the interpretation of the calculation results carried out with simpler models.
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Bibliography

[1] Ansys Inc, Ansys Fluent Theory Guide. Ansys Inc (2019).
[2] M. Baścik, 3D laser scanning in underground mines – practical experience. School of Underground Mining 2013. The Mineral And Energy Economy Research Institute of Polish Academy of Sciences (2013).
[3] P.Y. Chou, On velocity correlations and the solutions of the equations of turbulent fluctuations. Quarterely of Applied Mathematics (1945).
[4] N .S. Dhamakar, G.A. Blasdell, A.S. Lyrintzis, An Overview of Turbulent Inflow Boundary Conditions for large Eddy Simulations. Proc of the 22 nr AIAA Computational Fluid Dynamics Conference AIAA Paper (2015).
[5] W. Dziurzyński, Prognozowanie procesu przewietrzania kopalni głębinowej w warunkach pożaru podziemnego. Instytut Gospodarki Surowcami Mineralnymi i Energią PAN, Kraków (1998).
[6] J. Janus, PhD thesis, Modelling of flow phenomena in mine drifts using the results of laser scanning. Strata Mechanics Research Institute of Polish Academy of Sciences (2018).
[7] J. Janus, The Application of laser scanning in the process of constructing a mine drift numerical model. 24th World Mining Congress PROCEEDINGS – Underground Mining, Brazilian Mining Association, Rio de Janeiro (2016).
[8] J. Janus, The application of laser scanning in the process of construction a mine drift numerical model. Transactions of the Strata Mechanics Research Institute 18, 3 (2016).
[9] J. Janus, Assessment of the possibilities of using laser scanning for numerical models constructions. Transactions of the Strata Mechanics Research Institute 17, (1-2) (2015).
[10] J. Janus, Wpływ zapory przeciwwybuchowej wodnej na pole prędkości i warunki przewietrzania wyrobiska kopalnianego. Archives of Mining Sciences, Seria: Monografia, Nr 19 (2019).
[11] J. Janus, J. Krawczyk, An Analysis of the Mixing of Air and Methane in the Stream Produced by the Mine Injector Station – Present Results of Measurements and Modeling. The Australian Mine Ventilation Conference 2013, The Australian Institute of Mining and Metallurgy (2013).
[12] J. Janus, J. Krawczyk, Measurement and Simulation of Flow in a Section of a Mine Gallery. Energies 14, 4894 (2021). DOI: https://doi.org/10.24425/ather.2019.128295
[13] J. Janus, J. Krawczyk, The numerical simulation of a sudden inflow of methane into the end segment of a longwall with Y – type ventilation system. Archives of Mining Sciences 59, (4) (2014).
[14] A. Kidybiński, Podstawy geotechniki kopalnianej. Wydawnictwo Śląsk, Katowice (1982).
[15] J. Krawczyk, J. Janus, An example of defining boundary conditions for a flow in a mine gallery. Abstract in the XXIII Fluid Mechanics Conference Materials, Zawiercie (2018).
[16] J. Krawczyk, J. Janus, Velocity field in the area of artificially generated barrier on the mine drift floor. Przegląd Górniczy 71, (11) (2015).
[17] J. Krawczyk, Single and multiple-dimensional models of unsteady air and gas flows in underground mines. Archives of Mining Sciences, Seria: Monografia, No 2 (2007).
[18] F. Menter, Turbulence Modeling for Engineering Flows. ANSYS 2012 Inc. (2012). [19] F. Menter, Best Practice – Scale-Resolving Simulations in ANSYS CFD – Application Brief Version 2.0 (2015).
[20] J. Pokorný, L. Brumarová, P. Kučera, J. Martinka, A. Thomitzek, P. Zapletal, The effect of Air Flow Rate on Smoke Stratification in Longitudinal Tunnel Ventilation. Acta Montanistica Slovaca 24, (3) (2019).
[21] T. Ren, R. Balusu, C. Claassen, Computational Fluid Dynamics Modelling of Gas Flow Dynamics in Large Longwall Goaf Areas. 35th APCOM Symposium (2011).
[22] P. Skotniczny, Three-Dimensional Numerical Simulation of the Mass Exchange Between Longwall Headings and Goafs, in the Presence of Methane Drainage in A U-Type Ventilated Longwall. Archives of Mining Sciences 58, (3) (2013).
[23] V. Sokoła-Szewioła, J. Wiatr, Application of laser scanning method for the elaboration of digital spatial representation of the shape of underground mining excavation. Przegląd Górniczy 8 (2013).
[24] J. Szlązak, PhD thesis, Wpływ uszczelniania chodników przyścianowych na przepływ powietrza przez zroby. AGH Kraków (1980).
[25] N. Szlązak, J. Szlązak, Wentylacja wyrobisk ścianowych w kopalniach węgla kamiennego, w warunkach zagrożenia metanowego i pożarowego. Górnictwo i Geologia (2) (2019).
[26] K. Wierzbiński, Wpływ geometrii chodnika wentylacyjnego i sposobu jego likwidacji na rozkład stężenia metanu w rejonie wylotu ze ściany przewietrzanej sposobem U w świetle obliczeń numerycznych CFD. Zeszyt Naukowy Instytutu Gospodarki Surowcami Mineralnymi i Energią Polskiej Akademii Nauk, No 94 (2016).
[27] M.A. Wala, S. Vytla, C.D. Taylor, G. Huang, Mine face ventilation: a comparison of CFD results against benchmark experiments for the CFD code validation. Mining Engineering (2007).
[28] D.M. Worrall, E.W. Wachel, U. Ozbay, D.R. Munoz, J.W. Grubb, Computational fluid dynamic modeling of sealed longwall gob in underground coal mine – A progress report. 14th United States/North American Mine Ventilation Symposium, Calizaya & Nelson (2012).
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Authors and Affiliations

Jakub Janus
1
ORCID: ORCID

  1. Strata Mechanics Research Institute, 27 Reymonta Str., 30-059 Kraków, Poland
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Abstract

The paper presents the results of research on the kinetics of the binding process of self-hardening moulding sands with an organic binder under conditions of forced air flow at various pressure values. Three moulding sands made using urea-furfuryl resin Furanol FR75A technology were studied. The moulding sands were prepared on a base of quartz sand with an average grain size of dL = 0.25, 0.29 and and 0.37 mm , with permeability values of 306 , 391 and and 476 m 2/10 8Pa ∙ s (for ρ0 = 1.60 , 1.60 and and 1.61 g/cm 3, respectively). The research was conducted for a resin content of 1% with a constant proportion of hardener to resin, which was equal to 50%. Samples of the tested moulding sands were blown with air at pressures of 0.1, 0.2, 0.4, 0.6, 0.8, and 1.0 bar. The kinetics of the hardening process was monitored using ultrasound technology, according to a previously developed methodology [1]. The research was carried out on an ultrasound testing station equipped with a temperature chamber and an airflow reducer. The tests were conducted at a temperature of 20°C, and of the air flow pressure on the changes in ultrasonic wave velocity in the hardening mouldins sand as a function of time, the kinetics of the hardening process, and the degree of moulding sand hardening were determined. Additionally, the influence of the moulding sand permeability on the course of the hardening process at a constant air flow pressure was determined.
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Bibliography

[1] Zych, J. (2007). Synthesis of the applications of ultrasonic technology in the analysis of the kinetics of selected processes occurring in molding materials. AGH Uczelniane Wydawnictwa Naukowo-Dydaktyczne. Seria: Rozprawy i Monografie nr 163, Kraków. (in Polish).
[2] Holtzer, M., Kmita, A. & Roczniak, A. (2014). New furfuryl resins more environmentally friendly. Archives of Foundry Engineering. 14(spec.4), 51-54. (in Polish).
[3] Lewandowski, J.L. (1997). Materials for casting molds. Kraków: Wydawnictwo Akapit. (in Polish).
[4] Lewandowski, J.L (1971). Molding materials. Warszawa: Wydawnictwo Naukowe PWN. (in Polish).
[5] Dobosz, St.M. (2006). Water in molding and core sands. Kraków: Wydawnictwo Akapit. (in Polish).
[6] Drożyński, D. (1999). Post-surface phenomena in the process of binding masses in the classic cold-box technology. Unpublished doctoral dissertation, AGH Univesity of Science and Technology, Kraków. (in Polish).
[7] Lewandowski, J.L. (1991). Molding and core sands. Warszawa: Wydawnictwo Naukowe PWN. (in Polish).
[8] Jamrozowicz, Ł., Kolczyk, J. & Kaźnicva, N. (2016). Study of the hardening kinetics of self-hardening masses at low temperature. Prace Instytutu Odlewnictwa. LVI, 4/2016, 379-390. (in Polish).
[9] Matonis, N. & Zych, J. (2022). Plasticity changes of moulding sands with chemical binders caused by increasing the hardenin degree. Archives od Foundry Engineering. 22(2), 71-76. DOI: 10.24425/afe.2022.140227.
[10] Zych, J. (1999). Patent Nr PL 192202 B1. Kraków
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Authors and Affiliations

Natalia Matonis
1
ORCID: ORCID

  1. AGH University of Science and Technology, Faculty of Foundry Engineering, Poland

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