Spreading of Swirling Double–Concentric Jets at Low and High Pulsation Intensities
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.
[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.
[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.
@article{"International Journal of Mechanical, Industrial and Aerospace Sciences:61536", author = "Shiferaw R. Jufar and Rong F. Huang and Ching M. Hsu", title = "Spreading of Swirling Double–Concentric Jets at Low and High Pulsation Intensities", abstract = "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.", volume = "7", number = "6", pages = "1246-6", }