COMPARISON OF THE RESULTS OF THEORETICAL AND EXPERIMENTAL INVESTIGATIONS OF AIR FLOWS IN A SHAFT ABOVE AN ELECTRISITY HEATED ONE ROW BUNDLE OF FINNED PIPES

UDC 536.24:66.045

 

Karlovich Tatyana Borisovna − PhD (Physics and Mathematics), Assistant Professor, the Department of Mechanics and Design. Belarusian State Technological University (13a, Sverdlova str., 220006, Minsk, Republic of Belarus). E-mail: tbkar@mail.ru

Karlovich Aleksei Olegovich – student, faculty of mechanics and mathematics. Belarusian State University. (4, Nezavisimosti Ave, 220050, Minsk, Republic of Belarus). E-mail: aleksei.karlovich@gmail.com

Sukhotskii Albert Borisovich − PhD (Technical Sciences), Assistant Professor, the Department of Energy-Saving, Hydraulics and Heat Engineering. Belarusian State Technological University (13a, Sverdlova str., 220006, Minsk, Republic of Belarus). E-mail: alk2905@mail.ru

Danilchik Ekaterina Sergeevna – Assistant, the Department of Energy-Saving, Hydraulics and Heat Engineering. Belarusian State Technological University (13a, Sverdlova str., 220006, Minsk, Republic of Belarus). E-mail: katya.156.156@gmail.com

 

DOI: https://doi.org/ 10.52065/2520-6141-2023-272-2-5 (In Russian).

 

Key words: free convection, exhaust shaft, finned tube, Oberbek – Boussinesq approximation, Navier – Stokes equation, Rayleigh, Pandtl, Peclet numbers.

 

For citation: Karlovich T. B., Karlovich A. O., Sukhotskii A. B., Danil’chik E. S. Comparison of the results of theoretical and experimental investigations of air flows in a shaft above an electricity heated one row bundle of finned pipes. Proceedings of BSTU, issue 3, Physics and Mathematics. Informatics, 2023, no. 2 (272), pp. 27–033. DOI: 10.52065/2520-6141-2023-272-2-5 (In Russian).

 

Abstract

In this paper, the features of free convective air movement in an exhaust shaft above a single row bundle of finned tubes are experimentally and theoretically studied. The dependences of the shaft side wall temperature on the height above the heating surface were experimentally determined. The obtained dependences are approximated by a straight-line in numerical modeling based on the equations of thermogravitational convection, which take into account the nonzero air flow velocity in a mine. The influence of the covering material (paper and aluminum sheets) of the shaft bottom on the nature of air movement was experimentally studied. It is shown that there are no significant differences from the free passage of air through a bundle of finned tubes, since the process in all cases proceeds for Rayleigh numbers that significantly exceed the critical value. This property is used to simplify the boundary condition in the theoretical formulation of the problem. On the basis of numerical simulation, it is shown that the stationary state of the system exists only for Rayleigh numbers Ra < 40000. When this value is exceeded, quasi-periodic undamped oscillations of temperature and velocity are realized. It is shown that as the Peclet number increases, these oscillations stabilize.

 

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References

  1. Karlovich T. B., Sukhotskii A. B., Danil’chik E. S. Deformation of convective cells in a flat horizontal layer with permeable boundaries under a directional flow of a liquid. Trudy BGTU [Proceedings of BSTU], issue 3, Physics and Mathematics. Informatics, 2022, no. 2 (260), pp. 31–35 (In Russian).
  2. Karlovich T. B., Sukhotskii A. B., Danil’chik E. S. Rayleigh-Benard convection in an exhaust shaft above a single-row horizontal bundle of finned tubes. Trudy BGTU [Proceedings of BSTU], issue 3, Physics and Mathematics. Informatics, 2021, no. 2 (248), pp. 58–64 (In Russian).
  3. Shvartsblat D. L. On the spectrum of perturbations and convective instability of a flat horizontal liquid layer with permeable. Prikladnaya matematika i mekhanika [Applied Mathematics and Mechanics], 1968, issue 2, pp. 276–281 (In Russian).
  4. Gershuni G. Z., Zhukhovitskiy E. M., Nepomnyaschiy A. A. Ustoychivost’ konvektivnykh techeniy [Stability of convective flows]. Moscow, Nauka Publ., 1996. 319 p. (In Russian).
  5. Karlovich T. B., Sukhotskii A. B., Danil’chik E. S. Convective instability of air flows in the exhaust shaft above a four-row finned bundle. Vesti NAN Belarusi. Seriya fiz.-mat. nauk [Vesti NAS of Belarus], series of physics and mathematics, 2021, vol. 57, no. 2, pp. 242–254 (In Russian).
  6. Roache P. J. Computational fluid dynamics. Hermosa Publ., Albuquerque, 1976. 446 p.
  7. Gershuni G. Z., Zhuhovickiy E. M. Konvektivnaya ustoychivost’ neszhimayemoy zhidkosti [Convective stability of an incompressible fluid]. Moscow, Nauka Publ., 1972. 392 p. (In Russian).

 

Поступила после доработки 13.06.2023