THERMAL SCIENCE

International Scientific Journal

Thermal Science - Online First

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Characterization of critical stretch rate using outwardly propagating spherical flames

ABSTRACT
Outwardly propagating spherical flames within a constant volume combustion chamber (CVCC) are studied to analyse the non-linear relationship between flame stretch and flame speed, enabling a critical appraisal of a methodology proposed for characterizing the critical stretch rate. Four fuels, namely methane, propane, methanol and ethanol in air, are chosen to investigate the correlation between maximum critical stretch rate and the flame extinction across a range of equivalence ratios at various ambient conditions in under-driven flames, and to compare the hypothesis against data from the traditional counter-flowing flame technique. Flame propagation is recorded via high-speed Schlieren photography, and low ignition energies are achieved via a variable capacitive-discharge supply, enabling the critical early stages of flame propagation, critical stretch rate and the sensitivity of the non-linear methodology to ignition energy to be systematically analysed. The non-linear methodology shows partial agreement with extinction stretch rate from counter flowing flames, particularly in the case of gaseous fuels. Although the fuel vapour data lies between previous extinction stretch rate measurements using the counter-flowing flame methodology, and predictions from chemical kinetic schemes, a 40% deviation is observed. A mathematical expression was produced to determine the critical stretch at the specific conditions of the present work.
KEYWORDS
PAPER SUBMITTED: 2017-08-09
PAPER REVISED: 2018-02-16
PAPER ACCEPTED: 2018-02-16
PUBLISHED ONLINE: 2018-03-04
DOI REFERENCE: https://doi.org/10.2298/TSCI170809071R
REFERENCES
  1. Choudhuri A.R., et al., Flame Extinction Limits of H2‐CO Fuel Blends, Journal of Engineering for Gas Turbines and Power, 130 (2008), 3, pp. 031501-031508.
  2. Park O., et al., Combustion characteristics of alternative gaseous fuels, Proc. Combust. Inst. , 33 (2011), 1, pp. 887-894.
  3. Tomić M., et al., Closed Vessel Combustion Modelling by using Pressure-Time Evolution Function Derived from Two-Zonal Approach, Thermal Science, 16 (2012), 2, pp. 561-572.
  4. Wang C.H., et al., The extinction limits and near-limits behaviors of premixed ethanol/air flame, International Communications in Heat and Mass Transfer, 24 (1997), 5, pp. 695-708.
  5. Mansour M.S., Fundamental Study of Premixed Combustion Rates at Elevated Presure and Temperature, Ph. D. thesis, University of Leeds, UK, 2010.
  6. Lefebvre A.H., Ballal D.R., Gas Turbine Combustion. Alternative Fuels and Emissions, CRS Press, Taylor & Francis Group, Boca Raton, FL, USA, 2010.
  7. Geikie M.K., Ahmed K.A., Lagrangian mechanisms of flame extinction for lean turbulent premixed flames, Fuel, 194 (2017), pp. 239-256.
  8. Holley A.T., et al., Extinction of premixed flames of practical liquid fuels: Experiments and simulations, Combustion and Flame, 144 (2006), 3, pp. 448-460.
  9. Zhang Y., et al., Extinction limit and near-limit kinetics of lean premixed stretched H2-CO-air flames, International Journal of Hydrogen Energy, 41 (2016), 39, pp. 17687-17694.
  10. Veloo P.S., Egolfopoulos F.N., Studies of n-propanol, iso-propanol, and propane flames, Combustion and Flame, 158 (2011), 3, pp. 501-510.
  11. Ishizuka S., Law C.K., An experimental study on extinction and stability of stretched premixed flames, Symposium (International) on Combustion, 19 (1982), 1, pp. 327-335.
  12. Xu W., Jiang Y., Qiu R., Ren X., Influence of halon replacements on laminar flame speeds and extinction limits of hydrocarbon flames, Combustion and Flame, 182 (2017) 1-13.
  13. Bradley D., et al., Explosion bomb measurements of ethanol-air laminar gaseous flame characteristics at pressures up to 1.4 MPa, Combustion and Flame, 156 (2009), 7, pp. 1462-1470.
  14. Crayford A.P., et al., Laminar Burning Characteristics of Methane/Water-Vapour/air Flames, Proceedings, European Combustion Meeting, Cardiff, UK, 2011, Vol. 1, pp. 1-6.
  15. Kelley A.P., Law C.K., Nonlinear effects in the extraction of laminar flame speeds from expanding spherical flames, Combustion and Flame, 156 (2009), 9, pp. 1844-1851.
  16. Kim H.H., et al., Measurements of the critical initiation radius and unsteady propagation of n-decane/air premixed flames, Proc.Combust. Inst., 34 (2013), 1, pp. 929-936.
  17. De la Garza O.A., et al., Determination and introduction of the transport properties of soybean oil biodiesel in the CFD code OpenFOAM, Thermal Science, (2017 OnLine-First), doi. org/10.2298/TSCI170317157G.
  18. Ganji P.R., et al., Computational Optimization of Biodiesel Combustion using Response Surface Methodology, Thermal Science, 21 (2017), 1B, pp. 465-473.
  19. Carrera J.L., et al., Numerical study on the combustion process of a biogas spark ignition engine, Thermal Science, 17 (2013), 1, pp. 241-254.
  20. Chen Z., et al., Effects of Lewis number and ignition energy on the determination of laminar flame speed using propagating spherical flames, Proc. Combust. Inst., 32 (2009), 1, pp. 1253-1260.
  21. Chen Z., et al., On the critical flame radius and minimum ignition energy for spherical flame initiation, Proc. Combust. Inst., 33 (2011), 1, pp. 1219-1226.
  22. Omari A., Tartakovsky L., Measurement of the laminar burning velocityusing the confined and unconfined spherical flame methods - A comparative analysis, Combustion and Flame, 168 (2016), pp. 127-137.
  23. Crayford A.P., Suppression of Methane-Air Explosions with Water in the form of ‘Fine' Mists, Ph D. thesis, University of Wales, Cardiff, UK, 2004.
  24. Pugh D.G., et al., Parametric investigation of water loading on heavily carbonaceous syngases, Combustion and Flame, 164 (2016), pp. 126-136.
  25. Cameron L.R.J., Bowen P.J., Novel cloud chamber design for 'transition range' aerosol combustion studies, Process Safety and Environmental Protection, 79 (2001), 4, pp. 197-205.
  26. Rallis C.J., Garforth A.M., The determination of laminar burning velocity, Progress in Energy and Combustion Science, 6 (1980), 4, pp. 303-329.
  27. Bradley D., et al., The measurement of laminar burning velocities and Markstein numbers for iso-octane-air and iso-octane-n-heptane-air mixtures at elevated temperatures and pressures in an explosion bomb, Combustion and Flame, 115 (1998), 1-2, pp. 126-144.
  28. Lamoureux N., et al., Laminar flame velocity determination for H2-air-He-CO2 mixtures using the spherical bomb method, Experimental Thermal and Fluid Science, 27 (2003), 4, pp. 385-393.
  29. Giannakopoulos G.K., et al., Consistent definitions of "Flame Displacement Speed" and "Markstein Length" for premixed flame propagation, Combustion and Flame, 162 (2015), 4, pp. 1249-1264.
  30. Xu C., et al., Laminar flame characteristcs of ethanol-air mixture: Experimental and simulation study, Thermal Science, (2017 OnLine-First), doi.org/10.2298/TSCI161001112X .
  31. Tahtouh T., et al., Measurement of laminar burning speeds and Markstein lengths using a novel methodology, Combustion and Flame, 156 (2009), 9, pp. 1735-1743.
  32. Bradley D., et al., Burning velocities, Markstein lengths, and flame quenching for spherical methane-air flames: A computational study, Combustion and Flame, 104 (1996), 1-2, 176-198.
  33. Egolfopoulos F.N., et al., Wall effects on the propagation and extinction of steady, strained, laminar premixed flames, Combustion and Flame, 109 (1997), 1-2, pp. 237-252.
  34. Wu Y.C., Chen Z., Asymptotic analysis of outwardly propagating spherical flames, Acta Mechanica Sinica, 28 (2012), 2, pp. 359-366.
  35. Law C.K., Combustion Physics, Cambridge University Press, New York, USA, 2006.