Commenced in January 2007
Frequency: Monthly
Edition: International
Paper Count: 32451
Spreading of Swirling Double–Concentric Jets at Low and High Pulsation Intensities

Authors: Shiferaw R. Jufar, Rong F. Huang, Ching M. Hsu


The spreading characteristics of acoustically excited swirling double-concentric jets were studied experimentally. The central jet was acoustically excited at low and high pulsation intensities. A smoke wire flow visualization and a hot-wire anemometer velocity measurement results show that excitation forces a vortex ring to roll-up from the edge of the central tube during each excitation period. At low pulsation intensities, the vortex ring evolves downstream, and eventually breaks up into turbulent eddies. At high pulsation intensities, the primary vortex ring evolves and a series of trailing vortex rings form during the same period of excitation. The trailing vortex rings accelerate while evolving downstream and overtake the primary vortex ring within the same cycle. In the process, the primary vortex ring becomes unstable and breaks up early. The effect of the fast traveling trailing vortex rings combined with the swirl motion of the annular flow improve jet spreading compared with the naturally evolving jets.

Keywords: Acoustic excitation, double–concentric jets, flow control, swirling jet.

Digital Object Identifier (DOI):

Procedia APA BibTeX Chicago EndNote Harvard JSON MLA RIS XML ISO 690 PDF Downloads 1892


[1] A. K. Gupta, D. G. Lilley, and N. Syred, "Swirl flows," Abacus, Tunbridge Wells, Kent and Cambridge, Mass, 1984, pp. 13-17.
[2] R.F. Huang, and F.C. Tsai, "Observations of swirling flows behind circular disks," AIAA Journal, vol. 39, pp. 1106-1112, 2001.
[3] R.F. Huang, and F.C. Tsai, "Flow field characteristics of swirling double concentric jets, " Experimental Thermal and Fluid Science, vol. 25, pp. 151-161, 2001.
[4] R.F. Huang, and S.C. Yen, "Axisymmetric swirling vortical wakes modulated by a control disk," AIAA Journal, vol. 41, pp. 888-896, 2003.
[5] S.C. Crow, and F.H. Champagne, "Orderly structure in jet turbulence," Journal of Fluid Mechanics, vol. 48, pp. 547-591, 1971.
[6] S.K. Oh, and H.D. Shin, "A visualization study on the effect of forcing amplitude on tone-excited isothermal jets and jet diffusion flames," International Journal of Energy Research, vol. 22, pp. 343-354, 1998.
[7] K.M. Lee, T.K. Kim, W.J. Kim, S.G. Kim, J. Park, and S. N Keel, "A visual study on flame behavior in tone-excited non-premixed jet flames," Fuel, vol. 81, pp. 2249-2255, 2002.
[8] K.B.M.Q. Zaman, and A.K.M.F. Hussain, "Turbulence suppression in free shear flows by controlled excitation, Journal of Fluid Mechanics," vol. 103, pp. 133-159, 1981.
[9] K.B.M.Q. Zaman, and A.K.M.F. Hussain, "Vortex pairing in a circular jet under controlled excitation. Part 1. General jet response," Journal of Fluid Mechanics, vol. 101, pp. 449-491, 1980.
[10] S.V. Alekseenko, V.M. Dulin, Y.S. Kozorezov, and D.M. Markovich, "Effect of axisymmetric forcing on the structure of a swirling turbulent jet," International Journal of Heat and Fluid Flow, vol. 29, pp. 1699- 1715, 2008.
[11] T.K. Kim, J. Park, and H.D. Shin, "Mixing Mechanism near the Nozzle Exit in a Tone Excited Non-Premixed Jet Flame," Combustion Science and Technology, vol. 89, pp. 83-100, 1993.
[12] A. Olcay, and P. Krueger, "Measurement of ambient fluid entrainment during laminar vortex ring formation," Experiments in Fluids, vol. 44, pp. 235-247, 2008.
[13] R.F. Huang, S.R. Jufar, and C.M. Hsu, "Flow and mixing characteristics of swirling double-concentric jets subject to acoustic excitation," Experiments in Fluids, vol. 54, pp. 1-23, 2012.
[14] M. Gharib, E. Rambod, and K. Shariff, "A universal time scale for vortex ring formation," Journal of Fluid Mechanics, vol. 360, pp 121- 140, 1998.
[15] E. Aydemir, N. Worth, and J. Dawson, "The formation of vortex rings in a strongly forced round jet," Experiments in Fluids, vol. 52, pp. 729- 742, 2012.
[16] P.S. Krueger, J.O. Dabiri, and M. Gharib, "The formation number of vortex rings formed in uniform background co-flow," Journal of Fluid Mechanics, vol. 556, pp. 147-166, 2006.