Characteristics of Turbulent Round Jets in its Potential-Core Region

In this work, stationary hot-wire measurements are carried out to investigate the characteristics of a round free jet in its potential core region (0 ≤ x/d ≤ 10). Measurements are carried out on an incompressible round jet for a range of Reynolds numbers from 4000 to 8000, calculated based on the jet exit mean velocity and the nozzle diameter. The effect of flow velocity on the development characteristics of the jet in the core region is analyzed. Timeaveraged statistics, spectra of velocity and its higher order moments are presented and explained.

Authors:

• S. Sivakumar
• Ravikiran Sangras
• Vasudevan Raghavan

Keywords:

• Contoured nozzle
• hot-wire anemometer
• Reynolds number
• velocity fluctuations
• velocity spectra.

References:

[1] S. Sami, T. Carmody, and H. Rouse, "Jet diffusion in the region of flow
establishment," Journal of Fluid Mechanics, vol. 27, pp. 231-252,
1967.
[2] I. Wygnanski and H. Fiedler, "Some measurements in the selfpreserving
jet," Journal of Fluid Mechanics, vol. 38, pp. 577-612,
1969.
[3] P. N.R. and J. Lumley, "Turbulence measurements in axisymmetric jets
of air and helium. part 1. air jet," Journal of Fluid Mechanics, vol. 246,
pp. 197-223, 1993.
[4] L. Boguseawski and C. O. Popiel, "Flow structure of the free round
turbulent jet in the initial region," Journal of Fluid Mechanics, vol. 90,
pp. 531-539, 1979.
[5] A.-R. A.A., S. AI-Fahed, and W. Chakroun, "The near-field
characteristics of circular of jets at low reynolds numbers," Mechanics
Research Communications, vol. 23, pp. 313-324, 1996.
[6] F. H., C. Ball, and A. Pollard, "Reynolds number effects within the
development region of a turbulent round free jet," International Journal
of Heat and Mass Transfer, vol. 52, pp. 3943-3954, 2009.
[7] G. Xu and R. Antonia, "Effect of different initial conditions on a
turbulent round free jet," Experiments in Fluids, vol. 33, pp. 677-683,
2002.
[8] Q. W.R., "Upstream nozzle shaping effects on near field flow in round
turbulent free jets," European Journal of Mechanics B/Fluids, vol. 25,
pp. 279-301, 2006.
[9] J. Mi and G. Nathan, "Statistical properties of turbulent free jets issuing
from nine differently-shaped nozzles," Flow Turbulence Combustion,
vol. 84, pp. 583-606, 2010.
[10] T. Shakouchi, M. Kito, T. Sakamoto, K. Tsujimoto, and T. Ando, "Flow
control of jet flow by passive nozzle configuration changes,"
International Journal of Flow Control, vol. 1, pp. 73-85, 2009.
[11] S. Ashforth-Frost and K. Jambunathan, "Effect of nozzle geometry and
semi-confinement on the potential core of a turbulent axisymmetric free
jet," Int. Comm. Heat Mass Transfer, vol. 23, pp. 155-162, 1996.
[12] R. H.R. and T. Wong, "Velocity field characteristics of turbulent jets
from round tubes with coil inserts," Applied Thermal Engineering, vol.
22, pp. 1037-1045, 2002.
[13] P. Burattini, R. Antonia, S. Rajagopalan, and M. Stephens, "Effect of
initial conditions on the near-field development of a round jet,"
Experiments in Fluids, vol. 37, pp. 56-64, 2004.
[14] P. Burattini and L. Djenidi, "Velocity and passive scalar characteristics
in a round jet with grids at the nozzle exit," Flow, Turbulence and
Combustion, vol. 72, pp. 199-218, 2004.
[15] P. Suresh, K. Srinivasan, T. Sundararajan, and S. K. Das, "Reynolds
number dependence of plane jet development in the transitional
regime," Physics of Fluids, vol. 20, p. 044105, 2008.
[16] C. Olinto and S. Möller, "X-probe calibration using collis and william-s
equation," in 10o Brazilian Congress of Thermal Sciences and
Engineering, 2004.
[17] H. Mouri, M. Takaoka, A. Hori, and Y. Kawashima, "Probability
density function of turbulent velocity fluctuations," Phys. Rev. E, vol.
65, p. 056304, 2002.
[18] Stephen B. Pope, Turbulent Flows, New York: Cambridge University
Press, 2000, ch. 6.