Abstract
Transitional jet diffusion flames provide the link between dynamics of laminar and turbulent flames. In this study, instabilities and their interaction with the flow structure are explored in a transitional jet diffusion flame, with focus on isolating buoyancy effects. Experiments are conducted in hydrogen flames with fuel jet Reynolds number of up to 2,200 and average jet velocity of up to 54 m/s. Since the fuel jet is laminar at the injector exit, the transition from laminar to turbulent flame occurs by the hydrodynamic instabilities in the shear layer of fuel jet. The instabilities and the flow structures are visualized and quantified by the rainbow schlieren deflectometry technique coupled with a high-speed imaging system. The schlieren images acquired at 2,000 frames per second allowed exposure time of 23 μs with spatial resolution of 0.4 mm. Results identify a hitherto unknown secondary instability in the flame surface, provide explanation for the observed intermittency in the breakpoint length, show coherent vortical structures downstream of the flame breakpoint, and illustrate gradual breakdown of coherent structures into small-scale random structures in the far field turbulent region.
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References
Hottel, H.C., Hawthorne, W.R.: Diffusion in laminar flame jets. In: Proceedings of Combustion Institute. 3, 254–266 (1949)
Scholefield, D.A., Garside, J.E.: The structure and stability of diffusion flames. In: Proceedings of Combustion Institute. 3, 102–110 (1949)
Takeno, T., Kotani, Y.: Transition and structure of turbulent jet diffusion flames. Progress in astronautics and aeronautics, AIAA, New York, 56, 19–35 (1978)
Takahashi, F., Mizomoto, M., Ikai S.: Transition from laminar to turbulent free jet diffusion flames. Combust. Flame. 48, 85–95 (1982)
Coats, C.M., Zhao, H.: Transition and stability of turbulent jet diffusion flames. In: Proceedings of Combustion Institute. 22, 685–692 (1988)
Hedge, U., Zhou, L., Bahadori, M.Y.: The transition to turbulence of microgravity gas jet diffusion flames. Combust. Sci. Technol. 102, 95–113 (1994)
Agrawal, A.K., Albers B.W., Alammar, K.N.: Effects of buoyancy on transitional hydrogen gas jet diffusion flames. Combust. Sci. Technol. 177, 305–322 (2005)
Buckmaster, J., Peters, N.: The infinite candle and its stability – a paradigm for flickering diffusion flames. In: Proceedings of Combustion Institute. 21, 1829–1836 (1986)
Chen, L.D., Seaba, J.P., Roquemore, W.M., Goss, L.P.: Buoyant diffusion flames. In: Proceedings of Combustion Institute. 22, 677–684 (1988)
Ellzey, J.L., Laskey, K.J., Oran, E.S.: Effects of heat release and gravity on unsteady diffusion flame. In: Proceedings of Combustion Institute. 23, 1635–1640 (1990)
Lingens, A., Neemann, K., Meyer, J., Schreiber, M.: Instability of diffusion flames. In: Proceedings of Combustion Institute. 26, 1053–1061 (1996)
Katta, V.R., Roquemore, W.M.: Role of inner and outer structures in transitional jet diffusion flames. Combust. Flame. 92, 274–282 (1993)
Katta, V.R., Goss, L.P., Roquemore, W.M.: Numerical investigations of transitional H2/N2 jet diffusion flames. AIAA J. 32, 84–94 (1994)
Albers, B.W., Agrawal, A.K.: Schlieren analysis of an oscillating gas-jet diffusion flame. Combust. Flame. 119, 84–94 (1999)
Asendrych, D., Drobniak, S.: Buoyancy-driven coherent structures in free round flame. Flow Turbul. Combust. 67, 325–353 (2001)
Wong, T., Agrawal, A.K.: Quantitative measurements in an unsteady flame using high-speed rainbow schlieren deflectometry. Meas. Sci. Technol. 17, 1503–1510 (2006)
Yule, A.J., Chigier, N.A., Ralph, S., Boulderstone, R., Ventura, J.: Combustion-transition interaction in a jet flame. AIAA J. 19(6), 752–760 (1981)
Eickhoff, H.: Instability and coherent structures in jet flames. Recent contributions to fluid mechanics, pp. 50–57. Springer, Berlin (1982)
Yamashita, H., Kushida, G., Takeno, T.: Characteristics of turbulent fluctuations in jet diffusion flame. In: Proceedings of Combustion Institute. 24, 311–316 (1994)
Takeno, T.: Transition and structure of jet diffusion flame. In: Proceedings of Combustion Institute. 25, 1061–1073 (1994)
Roquemore, W.M., Chen, L.D., Goss, L.P., Lynn, W.F.: Structure of jet diffusion flames. In: Borghi, R., Murthy, S.N.B. (ed.) Turbulent Reacting Flows, Lecture Notes in Engineering, vol. 40, pp. 49–63. Springer, Berlin, Germany, (1989)
Mathew, J., Basu, A.J.: Reacting, circular mixing layers in transition to turbulence. Flow Turbul. Combust. 64, 71–93 (2000)
Jiang, X., Luo, K.H.: Spatial direct numerical solution of the large vortical structures in forced plumes. Flow Turbul. Combust. 64, 43–69 (2000)
Zhou, X., Luo, K.H., Williams, J.J.R.: Dynamic behavior in reacting plumes. In: Proceedings of Combustion Institute. 28, 2859–2865 (2000)
Zhou, X., Luo, K.H., Williams, J.J.R.: Numerical studies on vortex structures in the near field of oscillating diffusion flames. Heat and Mass Transfer. 37(2), 101–110 (2001)
Zhou, X., Luo, K.H., Williams, J.J.R.: Vortex dynamics in spatio-temporal development of reacting plumes. Combust. Flame. 129, 11–29 (2002)
Reinaud, J., Joly, L., Chassaing, P.: Numerical simulation of variable density mixing layer. In: ESAIM Proceedings, Third International Workshop on Vortex Flows and Related Numerical Methods 7, 359–368 (1999)
Reinaud, J., Joly, L., Chassaing, P.: The baroclinic secondary instability of the two-dimensional shear layer. Phys. Fluids 12(10), 2489–2505 (2000)
Smyth W.D.: Secondary Kelvin–Helmholtz instability in weakly stratified shear flow. J. Fluid Mech. 497, 67–98 (2003)
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Kolhe, P.S., Agrawal, A.K. Role of Buoyancy on Instabilities and Structure of Transitional Gas Jet Diffusion Flames. Flow Turbulence Combust 79, 343–360 (2007). https://doi.org/10.1007/s10494-007-9098-y
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DOI: https://doi.org/10.1007/s10494-007-9098-y