Role of chemiluminescence and radius of curvature in the stabilization of methane/helium lifted flames

Role of chemiluminescence and radius of curvature in the stabilization of methane/helium lifted flames

Narayan P. Sapkal

Department of Mechanical Engineering, Pukyong National University, Nam-gu, Busan 608-739, South Korea

Corresponding Author Email: 
narayanpsapk@pukyong.ac.kr
Page: 
1249-1255
|
DOI: 
https://doi.org/10.18280/ijht.360412
Received: 
19 August 2017
| |
Accepted: 
24 October 2018
| | Citation

OPEN ACCESS

Abstract: 

The stabilization mechanism of non-premixed jet flames of methane diluted with helium has been investigated experimentally. Effects of fuel mole fraction, XF,O and nozzle diameter, D on the lifted flame characteristics of diluted methane jets were studied. Such methane jet flames could be lifted despite the Schmidt number was less than unity. Regimes of lifted flames were evaluated according to Richardson number and liftoff height compared with the length of developing zone. Such flames obtained using D = 9.4 mm nozzle were stabilized due to buoyancy induced convection in buoyancy dominated regime whereas for D = 0.95 mm nozzle methane jet flames could be lifted even at nozzle exit velocities much higher than stoichiometric laminar flame speed in jet momentum dominated regime. The chemiluminescence intensities of OH* radical (good indicators of heat release rate) were measured using monochromatic system for these lifted flames. It was confirmed that, in jet-momentum dominated regime an increase in radius of curvature in addition to OH* concentration stabilizes such lifted flames. Heat release rate near the triple point inferred by the OH* chemiluminescence intensity was inversely proportional to XF,O and had maximum at blowout conditions.

Keywords: 

schmidt number, richardson number, buoyancy effect, chemiluminescence, edge flame speed

1. Introduction
2. Experimental Setup
3. Results and Discussion
4. Conclusion
5. Uncertainty
Acknowledgement
Nomenclature
  References

[1] Chung SH, Lee BJ. (1991). On the characteristics of laminar lifted flames in a non-premixed jet. Combustion and Flame 86: 62-72. https://doi.org/10.1016/0010-2180(91)90056-H

[2] Lee BJ, Chung SH. (1997). Stabilization of lifted tri- brachial flames in a laminar non-premixed jet. Combustion and Flame 109: 163-172. https://doi.org/10.1016/s0010-2180(96)00145-9

[3] Ko YS, Chung SH. (1999). Propagation of unsteady tri- brachial flames in laminar non-premixed jets. Combustion and Flame 118: 151-163. https://doi.org/10.1016/S0010-2180(98)00154-0

[4] Ko YS, Chung SH, Kim GS, Kim SW. (2000). Stoichiometry at the leading edge of a tri-brachial flame in laminar jets from Raman scattering technique. Combustion and Flame 123: 430-433. https://doi.org/10.1016/s0010-2180(00)00169-3

[5] Lee J, Won SH, Jin SH, Chung S., Fujita O, Ito K. (2003). Propagation speed of tribrachial (triple) flame of propane in laminar jets under normal and micro gravity conditions. Combustion and Flame 134: 411-420. https://doi.org/10.1016/s0010-2180(03)00115-9

[6] Ruetsch GR, Vervisch L, Lina´n A. (1995). Effects of heat release on triple flames Physics of Fluids 7: 1447-1454. https://doi.org/10.1063/1.868531

[7] Chen JY, Echekki T. (2001). Numerical study of buoyancy effects on the structure and propagation of triple flames, Combustion Theory and Modelling 5: 499-515. https://doi.org/10.1088/1364-7830/5/4/301

[8] Won SH, Chung SH, Cha MS, Lee BJ. (2000). Lifted flame stabilization in developing and developed regions of co-flow jets for highly diluted propane. Proceeding of the Combustion Institute 28: 2093-2099. https://doi.org/10.1016/s0082-0784(00)80618-9

[9] Smooke MD, Ern A, Tanoff MA, Valdati BA, Mohammed RK, Marran DF, Long MB. (1996). Computational and experimental study of no in an axisymmetric laminar diffusion flame. Symposium International on Combustion 26: 2161–2170. https://doi.org/10.1016/s0082-0784(96)80042-7

[10] Qin X, Puri IK, Aggarwal SK. (2002). Characteristics of lifted triple flames stabilized in the near field of a partially premixed axisymmetric jet. Proceeding of the Combustion Institute 29: 1565-1572. https://doi.org/10.1016/s1540-7489(02)80192-4

[11] Plessing T, Terhoeven P, Peters N, Mansour MS. (1998). An experimental and numerical study of a laminar triple flame. Combustion and Flame 115: 335-353. https://doi.org/10.1016/s0010-2180(98)00013-3

[12] Medwell PR, Blunck DL, Dally BB. (2014). The role of precursors on the stabilization of jet flames issuing into a hot environment. Combustion and Flame 161: 465-474. https://doi.org/10.1016/j.combustflame.2013.08.028

[13] Gordon RL, Masri AR, Mastorakos E. (2008). Simultaneous Rayleigh temperature, OH-and CH2O-LIF imaging of methane jets in a vitiated coflow. Combustion and Flame 155: 181-195. https://doi.org/10.1016/j.combustflame.2008.07.001

[14] Gordon RL, Masri AR, Mastorakos E. (2009). Heat release rate as represented by [OH] X [CH2O] and its role in auto-ignition. Combustion Theory and Modelling 13: 645-670.

[15] Fayoux A, Zahringer K, Gicquel O, Rolon JC. (2005). Experimental and numerical determination of heat release in counterflow premixed laminar flames. Proceeding of the Combustion Institute 30: 251-257. https://doi.org/10.1016/j.proci.2004.08.210

[16] Dworkin SB, Schaffer AM, Connelly BC, Long MB, Smooke MD, Puccio MA, McAndrew B, Miller JH. (2009). Measurements and calculations of formaldehyde concentration in a methane/N2/air, non-premixed flame: Implication for heat release rate. Proceeding of the Combustion Institute 32: 1311-1318. https://doi.org/10.1016/j.proci.2008.05.083

[17] Dawson JR, Worth NA. (2014). Flame dynamics and unsteady heat release rate of self-excited azimuthal modes inanannular combustor. Combustion and Flame 161: 2565-2578. https://doi.org/10.1016/j.combustflame.2014.03.021

[18] Chung SH. (2007). Stabilization, propagation and instability of tribrachial flames. Proceeding of the Combustion Institute 31: 877-892. https://doi.org/10.1016/j.proci.2006.08.117

[19] Larbi AA, Bounif A, Bouzit M. (2018). Comparisons of LPDF and MEPDF for lifted H2/N2 jet flame in a vitiated coflow. International Journal of Heat and Technology 36(1): 133-140. https://doi.org/https://doi.org/10.18280/ijht.360118

[20] Abderrahmane H, Brahim N, Abdelfatah B, Nouereddine A.M. (2017). Laminar natural convection of power-law fluid in a differentially heated inclined square cavity. Annales de Chimie – Science des Materiaux 41(3-4): 261-281. https://acsm.revuesonline.com/article.jsp?articleId=39945

[21] Buckmaster J, Peters N. (1988). The infinite candle and its stability-A paradigm for flickering diffusion flames. Symposium International on Combustion 21: 1829-1836. https://doi.org/10.1016/s0082-0784(88)80417-x