The dynamic field in turbulent round jet discharging into a co-flowing stream

Mohamed Hichem Gazzah, Nejmiddin Boughattas, Hafedh Belmabrouk, Rachid Said

.

DOI: 10.4236/ns.2010.26079                

Abstract

The effects of a co-flow on a spreading and entrainment rate of turbulent round jets have been studied numerically. The first and second order closure models are used and have been comp- ared with existing experimental data. The influence of theses models on the dynamic fields is examined. The results of the models in general agree well with the trends observed experiment- tally. The co-flowing imposed noticeable restri- ctions on the spreading and the turbulent mixing. Finally, an entrainment hypothesis has been introduced to describe the development of turbulent jets issuing into a stagnant or co-flowing air. It relates the mass flow rate of the surround- ing fluid entrained into the jet to the characteristic velocity difference between the jet and the co-flow. It is obvious that the co-flow decreases considerably the entrainment of air.

Keywords

Co-Flow; Turbulence; Jets; Models; Entrainment

Conflicts of Interest

The authors declare no conflicts of interest.

References

[1]	Panchapakesan, N.R. and Lumley, J.L. (1993) Turbulence measurements in axisymmetric jets of air and hel- ium, Part 2. Helium jet. Journal of Fluid Mechanics, 246, 225-247.
[2]	Ruffin, E., Schiestel, E., Anselmet, F., Amielh, M. and Fulachier, L. (1994) Investigation of characteristic scales in variable density turbulent jets using a second-order model. Physics of Fluids, 6(8), 2785-2799.
[3]	Chassaing, P., Harran, G. and Joly, L. (1994) Density flu- ctuation correlations in free turbulent binary mixing. Journal of Fluid Mechanics, 279, 239-278.
[4]	Lucas, J.F. (1998) Analyse du champ scalaire au sein d’un jet turbulent axisymétrique à densité variable. Ph.D. Thesis, Université d’Aix-Marseille II, Marseille.
[5]	Gazzah, M.H., Sassi, M., Sarh, B. and Gökalp, I. (2002) Simulation numérique des jets turbulent subsoniques à masse volumique variable par le modèle k-ε. International Journal of Thermal Sciences, 41, 51-62.
[6]	Imine, B., Saber-Bendhina, A., Imine, O. and Gazzah, M.H. (2005) Effects of a directed co-flow on a non-reactive turbulent jet with variable density. International Journal of Heat and Mass Transfer, 42(1), 39-50.
[7]	Gazzah, M.H., Belmabrouk, H. and Sassi, M. (2004) A numerical study of the scalar field in turbulent round jet with co-flowing stream. Computational Mechanics, 34(5), 430-437.
[8]	Gazzah, M.H., Belmabrouk, H. and Sassi, M. (2005) Scalar transport modelling in turbulent round jets with co-flowing stream. International Journal of Thermal Sciences, 44(8), 766-773.
[9]	Borean, J.L., Huilier, D. and Burnage, H. (1998) On the effect of a co-flowing stream on the structure of an axisymmetric turbulent jet. Experimental Thermal and Fluid Science, 17(1-2), 10-17.
[10]	Schefer, R.W. and Dibble, R.W. (2001) Mixture fraction field in a turbulent non-reacting propane jet. American Institute of Aeronautics and Astronautics Journal, 39(1), 64-72.
[11]	Antoine, Y., Lemoine, F. and Lebouché, M. (2001) Turbulent transport of a passive scalar in a round jet discharging into a co-flowing stream. European Journal of Mechanics - B/Fluids, 20(2), 275-301.
[12]	Hakem, M., Hazzab, A. and Ghenaim, A. (2007) Experimental investigation of elliptical jet in coflow. International Journal of Applied Engineering Research, 2(1), 31-43.
[13]	Wang, P., Fröhlicha, J., Michelassib, V. and Rodi, W. (2008) Large-eddy simulation of variable-density turbul- ent axisymmetric jets. International Journal of Heat and Fluid Flow, 29(3), 654-664.
[14]	Curtet, R. (1957) Contribution à l’étude théorique des jets de revolution. Extrait des Comptes rendus de l’Aca- démie des Sciences, 244, 1450-1453.
[15]	Steward, F.R. and Gurus, A.G. (1977) Aerodynamic of a confined jet with variable density. Combustion Science and Technology, 16(1-2), 29-45.
[16]	Djeridane, T. (1994) Contribution à l’étude expérimentale de jets turbulents axisymétriques à densité variable. Ph.D. Thesis, Université d’Aix-Marseille II, Marseille.
[17]	Schiestel, R. (1993) Modélisation et simulation des écoulements turbulents. Hermès Group, Paris.
[18]	Patankar, S.V. (1980) Numerical heat transfer and fluid flow. Hemisphere Publishing, Washington, D.C.
[19]	Laufer, J. (1953) The structure of turbulence in fully developed pipe flow. National Advisory Committee for Aeronautics–Report–1174, 417-434.
[20]	Chen, C.J. and Rodi, W. (1980) Vertical turbulent buo- yant jets–a review of experimental data. The Science and Application of Heat and Mass Transfer, Pergamon Press, New York.
[21]	Gharbi, A., Ruffin, E., Anselmet, F. and Schiestel, R. (1996) Numerical modelling of variable density turbulent jets. International Journal of Heat and Mass Transfer, 39(9), 1865-1882.
[22]	Sanders, J.P.H., Sarh, B. and Gökalp, I. (1997) Variable density effects in axisymmetric isothermal turbulent jets: a comparison between a first-and a second-order turbulence model. International Journal of Heat and Mass Transfer, 40(4), 823-842.