No data available.

Please log in to see this content.

You have no subscription access to this content.

No metrics data to plot.

The attempt to load metrics for this article has failed.

The attempt to plot a graph for these metrics has failed.

The full text of this article is not currently available.

oa

Scalar dissipation rate statistics in turbulent swirling jets

### Abstract

The scalar dissipation rate statistics were measured in an isothermal flow formed by discharging a central jet in an annular stream of swirling air flow. This is a typical geometry used in swirl-stabilised burners, where the central jet is the fuel. The flow Reynolds number was 29 000, based on the area-averaged velocity of 8.46 m/s at the exit and the diameter of 50.8 mm. The scalar dissipation rate and its statistics were computed from two-dimensional imaging of the mixture fraction fields obtained with planar laser induced fluorescence of acetone. Three swirl numbers, S, of 0.3, 0.58, and 1.07 of the annular swirling stream were considered. The influence of the swirl number on scalar mixing, unconditional, and conditional scalar dissipation rate statistics were quantified. A procedure, based on a Wiener filter approach, was used to de-noise the raw mixture fraction images. The filtering errors on the scalar dissipation rate measurements were up to 15%, depending on downstream positions from the burner exit. The maximum of instantaneous scalar dissipation rate was found to be up to 35 s^{−1}, while the mean dissipation rate was 10 times smaller. The probability density functions of the logarithm of the scalar dissipation rate fluctuations were found to be slightly negatively skewed at low swirl numbers and almost symmetrical when the swirl number increased. The assumption of statistical independence between the scalar and its dissipation rate was valid for higher swirl numbers at locations with low scalar fluctuations and less valid for low swirl numbers. The deviations from the assumption of statistical independence were quantified. The conditional mean of the scalar dissipation rate, the standard deviation of the scalar dissipation rate fluctuations, the weighted probability of occurrence of the mean conditional scalar dissipation rate, and the conditional probability are reported.

Received 24 March 2016
Accepted 10 June 2016
Published online 11 July 2016

Acknowledgments:
The current research was supported by the Alan Howard scholarship for Energy Futures. The authors would also like to acknowledge financial contribution by EPSRC Grant No. GR/R01750/01. Yannis Hardalupas, Nikos Soulopoulos, and Alex Taylor would also like to acknowledge support from EPSRC Grant No. GR/R54767/01.

Article outline:

I. INTRODUCTION
II. EXPERIMENTAL ARRANGEMENT AND INSTRUMENTATION
A. Experimental setup
B. Data processing
C. Uncertainty in flow rate measurements
III. RESULTS AND DISCUSSIONS
A. Mixture fraction distribution
B. Instantaneous and mean scalar dissipation rate
C. Unconditional statistics
D. Joint statistics between scalar and its dissipation rate
E. Conditional scalar dissipation rate
IV. CONCLUSIONS

/content/aip/journal/pof2/28/7/10.1063/1.4954657

5.

J. Janicka and N. Peters, “Prediction of turbulent jet diffusion flame lift-off using a PDF transport equation,” in 19th Symposium (International) on Combustion (The Combustion Institute, Pittsburgh, 1982), p. 367.

http://dx.doi.org/10.1016/S0082-0784(82)80208-7
6.

A. N. Kolmogorov, “A refinement of previous hypothesis concerning the local structure of turbulence in a viscous incompressible fluid at high Reynolds number,” J. Fluid Mech. 13, 82 (1962).

http://dx.doi.org/10.1017/S0022112062000518
9.

H. Pitsch and S. Fedotov, “Investigation of scalar dissipation rate fluctuations in non-premixed turbulent combustion using a stochastic approach,” Combust. Theory Modell. 5, 41 (2000).

http://dx.doi.org/10.1088/1364-7830/5/1/303
12.

A. Sahay and E. O’Brien, “Uniform mean scalar gradient in grid turbulence: Conditioned dissipation and production,” Phys. Fluids A 5, 1076 (1993).

http://dx.doi.org/10.1063/1.858623
15.

G.-H. Wang, N. T. Clemens, R. S. Barlow, and P. L. Varghese, “A system model for assessing scalar dissipation measurement accuracy in turbulent flows,” Meas. Sci. Technol. 18(5), 1287 (2007).

http://dx.doi.org/10.1088/0957-0233/18/5/015
17.

R. W. Dibble, W. Kollman, and R. W. Schafer, “Measurements and predictions of scalar dissipation in turbulent jet flames,” in 20th Symposium (International) on Combustion (The Combustion Institute, 1984), p. 345.

18.

E. Effelsberg and N. Peters, “Scalar dissipation rates in turbulent jets and jet diffusion flames,” in 22nd Symposium (International) on Combustion (The Combustion Institute, 1988), p. 693.

20.

J. A. Sutton and J. F. Driscoll, “Scalar dissipation rate measurements in flames. A method to improve spatial resolution by using nitric oxide PLIF,” in Proceedings of the Combustion Institute 29 (Elsevier, 2002), p. 2727.

http://dx.doi.org/10.1016/S1540-7489(02)80332-7
21.

D. C. Kyritsis, V. S. Santoro, and A. Gomez, “Quantitative scalar dissipation rate measurements in vortex-perturbed counterflow diffusion flames,” in Proceedings of the Combustion Institute 29 (Elsevier, 2002), p. 1679.

http://dx.doi.org/10.1016/S1540-7489(02)80206-1
22.

D. Wang and C. Tong, “Experimental study of velocity-scalar filtered joint density function for LES of turbulent combustion,” in Proceedings of the Combustion Institute 30 (Elsevier, 2005), p. 567.

http://dx.doi.org/10.1016/j.proci.2004.08.032
23.

C. N. Markides and E. Mastorakos, “Measurements of scalar dissipation in a turbulent plume with planar laser-induced fluorescence of acetone,” Chem. Eng. Sci. 61, 2835 (2006).

http://dx.doi.org/10.1016/j.ces.2005.10.040
24.

N. Soulopoulos, “Experimental investigation of scalar mixing in unsteady turbulent jets,” Ph.D. thesis, Imperial College London, Mechanical Engineering Department, 2009.

26.

Jayesh and Z. Warhaft, “Probability distribution, conditional dissipation and transport of passive temperature fluctuations in grid generated turbulence,” Phys. Fluids A 4 (1992).

http://dx.doi.org/10.1063/1.858469
27.

P. Kailasnath, K. R. Sreenivasan, and J. R. Saylor, “Conditional scalar dissipation rates in turbulent wakes, jets and boundary layers,” Phys. Fluids A 5, 3207 (1993).

http://dx.doi.org/10.1063/1.858677
29.

T. F. Dixon, J. S. Truelove, and T. F. Wall, “Aerodynamic studies on swirled coaxial jets from nozzles with divergent quarls,” J. Fluids Eng. 105, 197 (1983).

http://dx.doi.org/10.1115/1.3240964
30.

V. D. Milosavljevic, “Natural gas, kerosene and pulverized fuel fired swirl burners,” Ph.D. thesis,Imperial College of Science Technology and Medicine, Department of Mechanical Engineering, 1993.

31.

W. Steenbergen, “Turbulent pipe flow with swirl,” Ph.D. thesis, Technishe Universiteit Eindhoven, Netherlands, 1995.

33.

M. Petrou and P. Bosdogianni, Image Processing: The Fundamentals (John Wiley & Sons Ltd., 1999).

35.

M. C. Thurber, “Acetone laser-induced fluorescence for temperature and multiparameter imaging in gaseous flows,” Topical Report TSD-120, Thermosciences Division, Department of Mechanical Engineering, Stanford University, Stanford, CA, 1999.

36.

D. A. Everest, J. F. Driscoll, W. J. A. Dahm, and D. A. Feikema, “Images of two dimensional field and temperature gradients to quantify mixing rates within a nonpremixed turbulent jet flame,” Combust. Flame 101, 58 (1995).

http://dx.doi.org/10.1016/0010-2180(94)00193-V
38.

K. R. Sreenivasan, R. A. Antonia, and H. Q. Dahn, “Temperature dissipation fluctuations in a turbulent boundary layer,” Phys. Fluids 20, 1238 (1977).

http://dx.doi.org/10.1063/1.862005
40.

H. Tennekes and J. L. Lumley, A First Course in Turbulence (The MIT Press, 1972).

41.

V. Stetsyuk, N. Soulopoulos, Y. Hardalupas, and A. M. K. P. Taylor, “Experimental assessment of presumed filtered density function models,” Phys. Fluids 27, 065107 (2015).

http://dx.doi.org/10.1063/1.4922169
42.

V. Stetsyuk, “Experimental study of combustion and scalar mixing in swirling jet flows,” Ph.D. thesis, Imperial College London, Department of Mechanical Engineering, 2014.

http://aip.metastore.ingenta.com/content/aip/journal/pof2/28/7/10.1063/1.4954657

Article metrics loading...

/content/aip/journal/pof2/28/7/10.1063/1.4954657

2016-07-11

2016-09-28

### Abstract

The scalar dissipation rate statistics were measured in an isothermal flow formed by discharging a central jet in an annular stream of swirling air flow. This is a typical geometry used in swirl-stabilised burners, where the central jet is the fuel. The flow Reynolds number was 29 000, based on the area-averaged velocity of 8.46 m/s at the exit and the diameter of 50.8 mm. The scalar dissipation rate and its statistics were computed from two-dimensional imaging of the mixture fraction fields obtained with planar laser induced fluorescence of acetone. Three swirl numbers, S, of 0.3, 0.58, and 1.07 of the annular swirling stream were considered. The influence of the swirl number on scalar mixing, unconditional, and conditional scalar dissipation rate statistics were quantified. A procedure, based on a Wiener filter approach, was used to de-noise the raw mixture fraction images. The filtering errors on the scalar dissipation rate measurements were up to 15%, depending on downstream positions from the burner exit. The maximum of instantaneous scalar dissipation rate was found to be up to 35 s^{−1}, while the mean dissipation rate was 10 times smaller. The probability density functions of the logarithm of the scalar dissipation rate fluctuations were found to be slightly negatively skewed at low swirl numbers and almost symmetrical when the swirl number increased. The assumption of statistical independence between the scalar and its dissipation rate was valid for higher swirl numbers at locations with low scalar fluctuations and less valid for low swirl numbers. The deviations from the assumption of statistical independence were quantified. The conditional mean of the scalar dissipation rate, the standard deviation of the scalar dissipation rate fluctuations, the weighted probability of occurrence of the mean conditional scalar dissipation rate, and the conditional probability are reported.

Full text loading...

/deliver/fulltext/aip/journal/pof2/28/7/1.4954657.html;jsessionid=B8sM4baF3bG9iiaKPLF4Gt_h.x-aip-live-03?itemId=/content/aip/journal/pof2/28/7/10.1063/1.4954657&mimeType=html&fmt=ahah&containerItemId=content/aip/journal/pof2

###
Most read this month

Article

content/aip/journal/pof2

Journal

5

3

true

true

Commenting has been disabled for this content