Using URANS to Predict Turbulent Flow Features in a Channel with Lateral Slot

Abstract:

Employing a commercial code an unsteady Reynolds Average Navier-Stokes (URANS) with Spalart-Allmaras as turbulence model numerical calculations were performed in order to predict the mean and velocity fluctuations fields in a rectangular channel with a lateral slot. The slot is attached to a lateral wall channel, being characterized by its deepness p and the gap width d. Simulations were performed keeping constant the slot deepness p and the length L while the gap width d was increased from 2 up to 6 mm. Three test sections involving p/d ratios12.50, 6.25 and 4.17were studied. Main results revealed that turbulence production increases with gap dimension decreasing. Large scale structures appearance were also the target of this paper. The study showed gap width plays an important role on this issue. As the gap width was increased large scales structures could be observed farther from channels entrance. Moreover, a kind of viscous effect in the gap was observed. As gap become very tight the frequency of coherent motions is reduced.

• Periodical: Applied Mechanics and Materials (Volume 394)
• Pages: 101-107
• DOI: https://doi.org/10.4028/www.scientific.net/AMM.394.101
• Online since: September 2013
• Authors: Tiago de Melo, Jhon Goulart, Sandi Souza
• Keywords: Channel with Slot, Compound Channels, Large Scale Structures, Turbulent Flow, URANS

References

[1] Goulart, Jhon Nero Vaz. Escoamentos Cisalhantes em Canais Compostos. 2009. 105 f. Tese (Doutorado em Engenharia Mecânica) – Porgrama de Pós-Graduação em Engenharia Mecânica – Universidade Federal do Rio /grande do Sul.

DOI: 10.20906/cps/con-2016-0537

[2] Goulart, J. N. V. and Möller, S. V., Flow pulsations in short compound channels. In: 11º Congresso Brasileiro de Engenharia e Ciências Térmicas - ENCIT, 2006, Coritiba, (2006).

[3] Goulart, J. N. V. and Möller, S. V., Shear Flow in Compound Channels: In: 19th International Congress of Mechanical Engineering – COBEM, 2006, Brasília, (2007).

[4] Goulart, J. N. V. and Möller, S. V., Turbulent Flow in Closed Compound Channels. In: 12th Brazilian Congress of Thermal Science and Engineering - ENCIT, 2008, Belo Horizonte, (2008).

[5] Home, D., Arvanitis, G., Linghtstone, M. F. ans Hamed, M. S., Simulation of flow pulsation in a twin rectangular subchannel geometry using unsteady Reynolds average Navier-Stokes modelling, Nuclear Engineering and Design, 239, 2964-2980, (2009).

DOI: 10.1016/j.nucengdes.2009.09.013

[6] Knight, D.W. and Shiono, K., Turbulence measurements in a shear-layer region of a compound channel, Journal of Hydraulic Research, 28, 175-196, (1990).

DOI: 10.1080/00221689009499085

[7] Meyer, L. and Rehme, K., Large-scale turbulence phenomena in compound rectangular channels, Experimental Thermal and Fluid Science, 8, 286-304, (1994).

DOI: 10.1016/0894-1777(94)90059-0

[8] Meyer, L. and Rehme, K., Periodic vortices in flow though channels with longitudinal slots or fins, 10th Symposium on Turbulent Shear Flows, The Pennsylvania State University, University Park, August 14-16, (1995).

[9] Meyer, L., From Discovery to Recognition of Periodic Large Scale Vortices in Rod Bundles as Source of Natural Mixing between Subchannels - A Review -, The 13th International Topical Meeting on Nuclear Reactor Thermal Hydraulics (NURETH-13), Kanazawa City, Ishikawa Prefecture, Japan, September 27-October 2, (2009).

DOI: 10.1016/j.nucengdes.2010.03.014

[10] Möller, S. V., On Phenomena of Turbulent Flow through Rod Bundles. Experimental Thermal and Fluid Science, 4, 25-35, (1991).

DOI: 10.1016/0894-1777(91)90018-m

[11] Rowe, D.S., Johnson, B.M. and Knudsen, J. G., Implications concerning rod bundle crossflow mixing based on measurements of turbulent flow structure, Int. J. Heat Mass Transfer, 17, 407-419, (1974).

DOI: 10.1016/0017-9310(74)90012-x

[12] Soldini, L., Piattella, A., Brocchini, M., Mancinelli, A. e Bernetti, R. Macrovortices-induced horizontal mixing in compound channels, Ocean Dynamics, 54, 333 – 339, (2004).

DOI: 10.1007/s10236-003-0057-4

[13] Spalart, P. R., Allmaras, S.R., A one-equation turbulence model for aerodynamic flow. In: 30th Aerospace Science Meeting and Exhibit, Reno, Nevada, (1992).

DOI: 10.2514/6.1992-439

[14] Wu, X. and Trupp, A. C., Spectral Measurements and Mixing Correlations in a Simulated Rod Bundle Subchannels, Int. J. Heat Transfer, 37 (1994) 1277-1281.

DOI: 10.1016/0017-9310(94)90212-7

[15] Chang, D e Tavoularis, S, Simulations of Turbulence, heat transfer and mixing across narrow gaps between rod-bundle subchannels, Nuclear Engineering and Design, 238 (2008) 109-123.

DOI: 10.1016/j.nucengdes.2007.06.001