Fire Science and Engineering (한국화재소방학회논문지)

Korean Institute of Fire Science and Engineering (한국화재소방학회)
권호 표지
DOI QR코드

DOI QR Code

Numerical Study on the Reacting Flow Field abound Rectangular Cross Section Bluff Body

사각 둔각물체 주위의 반응유동장에 대한 수치적 연구

  • Lee, Jung-Ran (Department of Safety Engineering, Pukyong National University) ;
  • Lee, Eui-Ju (Department of Safety Engineering, Pukyong National University)
  • 이정란 (부경대학교 안전공학과) ;
  • 이의주 (부경대학교 안전공학과)
  • Received : 2013.11.11
  • Accepted : 2013.12.06
  • Published : 2013.12.31
Download PDF
⟨ Previous Next ⟩

Abstract

The Numerical simulation was performed on the flow field around the two-dimensional rectangular bluff body in order to simulate an engine nacelle fire and to complement the previous experimental results of the bluff body stabilized flames. Fire Dynamic Simulator (FDS) based on the Direct Numerical Simulation (DNS) was employed to clarify the characteristics of reacting flow around bluff body. The overall reaction was considered and the constant for reaction was determined from flame extinction limits of experimental results. The air used atmosphere and the fuel used methane. For both fuel ejection configurations against an oxidizer stream, the flame stability and flame mode were affected mainly by vortex structure near bluff body. In the coflow configuration, air velocity at the flame extinction limit are increased with fuel velocity, which is comparable to the experiment results. Comparing with the isothermal flow field, the reacting flow produces a weak and small recirculation zone, which is result in the reductions of density and momentum due to temperature increase by reaction in the wake zone.

본 연구에서는 엔진 나셀 화재를 모사하고 이전의 실험결과를 보충하기위해 이차원 둔각물체 주위의 반응유동장에 대하여 수치해석을 수행하였다. Direct numerical simulation (DNS) 기반의 fire dynamic simulator (FDS)를 이용하여 반응유동장의 특성을 조사하였고, 실험결과와의 비교를 통해 화학반응식을 결정하였다. 산화제는 공기를 사용하였고, 연료는 메탄을 사용하였다. 동축류와 대향류 분사 모두의 경우에 화염의 안정성이나 모양은 둔각물체 주위의 와 강도와 크기에 크게 영향을 받았다. 동축류 분사의 경우 계산에 통한 화염소화한계를 결정하였는데 연료유속이 커질수록 공기의 유속 또한 커지는 경향이 있었고, 그 속도들 또한 기존의 실험결과와 잘 일치함을 볼 수 있었다. 유동장 특성에 대한 화학반응의 효과를 고찰하기 위해 반응이 없는 경우를 계산하여 비교하였다. 모든 경우에 비반응 유동장에 비해 반응 유동장의 후류와는 크기도 감소하고 세기도 감소함을 볼 수 있었는데 이는 반응에 의한 후류의 온도증가가 유체의 밀도 및 모멘텀을 감소시켰기 때문으로 판단된다.

Keywords

References

  1. J. R. Lee and E. J. Lee, "The Characteristic of Extinguishment of Engine Nacelle Fire using a Bluff Body", Journal of the Korean Society of Safety, Vol. 27, No. 1, pp. 21-25 (2012).
  2. J. R. Lee and E. J. Lee, "Numerical Study on the Isothermal Flow Field abound Rectangular Cross Section Bluff Body", Journal of the Korean Society of Safety, Vol. 27, No. 5, pp. 35-41 (2012).
  3. F. Takahashi, W. J. Schmoll and V. M. Belovich, "Suppression of Bluff-Body Stabilized Diffusion Flames", AIAA, pp. 98-3529 (1998).
  4. S. J. Shanbhogue, S. Husain and T. Lieuwen, "Lean Blowoff of Bluff Body Stabilized Flames: Scaling and Dynamics", Progress in Energy and Combustion Science, Vol. 35, pp. 98-120 (2009). https://doi.org/10.1016/j.pecs.2008.07.003
  5. I. Esquiva-Danoa, H. T. Nguyena and D. Escudiea, "Influence of a Bluff-Body's Shape on the Stabilization Regime of Non-Premixed Flames", Combust and Flame Vol. 127, pp. 2167-2180 (2001). https://doi.org/10.1016/S0010-2180(01)00318-2
  6. B. B. Dallya, A. R. Masria, R. S. Barlowb, G. J. Fiechtnerb and D. F. Fletcher, "Measurements of NO in Turbulent Non-Premixed Flames Stabilized on a Bluff Body", Proc. Combust. Inst., Vol. 26, pp. 2191-2197 (1996). https://doi.org/10.1016/S0082-0784(96)80045-2
  7. A. Kempfa, R. P. Lindstedta and J. Janickab, "Large-Eddy Simulation of a Bluff-Body Stabilized Nonpremixed Flame", Combust and Flame, Vol. 144, pp. 170-189 (2006). https://doi.org/10.1016/j.combustflame.2005.07.006
  8. B. B. Dallya, D. F. Fletcherb and A. R. Masria, "Flow and Mixing Fields of Turbulent Bluff-Body Jets and Flames", Combustion Theory and Modelling, Vol. 2, Issue 2, pp. 193-219 (1998). https://doi.org/10.1088/1364-7830/2/2/006
  9. Y. Chen, C. Chang, K. Pan and J. Yang, "Flame Lift-off and Stabilization Mechanisms of Nonpremixed Jet Flames on a Bluff-body Burner", Combustion and Flame, Vol. 115, pp. 51-65 (1998). https://doi.org/10.1016/S0010-2180(97)00336-2
  10. P. Koutmos, C. Mavridis and D. Papailiou, "A Study of Turbulent Diffusion Flames Formed by Planar Fuel Injection into the Wake Formation Region of a Slender Square Cylinder", Proc. Combust. Inst., Vol. 26, pp. 161-168 (1996). https://doi.org/10.1016/S0082-0784(96)80213-X
  11. A. G. Bakrozis, D. Papailiou and P. Koutmos, "A Study of the Turbulent Structure of a Two-Dimensional Diffusion Flame Formed Behind a Slender Bluff-Body", Combust and Flame, Vol .119, pp. 291-306 (1999). https://doi.org/10.1016/S0010-2180(99)00061-9
  12. D. Papailiou, P. Koutmos and A. G. Bakrozis, "Simulations of Fuel Injection and Flame Stabilization in the Wake Formation Region of a Slender Cylinder", Proc. Combust. Inst., Vol. 28, pp. 91-99 (2000). https://doi.org/10.1016/S0082-0784(00)80199-X
  13. P. Koutmos, D. Papailiou and A. Bakrozis, "Experimental and Computational Study of Square Cylinder Wakes with Two-Dimensional Injection into the Base Flow Region", European J. Mech. B/Fluids, Vol. 23, Issue 2, pp. 353-365 (2004). https://doi.org/10.1016/j.euromechflu.2003.09.004
  14. B. J Armstrong and F. H Barnes, "A Comparison of the Structure of the Wake behind a Circular Cylinder in a Steady Flow with That in a Perturbed Flow", Physics of Fluid, Vol. 30, Issue 1, pp. 19-26 (1987). https://doi.org/10.1063/1.866170
  15. I. Esquiva-Dano, H. T. Hguyen and D. Escudie, "Influence of a Bluff-Body's Shape on the Stabilization regime of Non-premixed Flames", Combustion and Flame, Vol. 127, pp. 2167-2180 (2001). https://doi.org/10.1016/S0010-2180(01)00318-2
  16. K. McGrattan, B. Kelin, S. Hostikka and J. Floyd, "Fire Dynamics Simulator User's Guide", NIST special publication 1019-5 (2005).
  17. I. Glassman and R. A. Tetter, "Combustion", Elsevier, San Diago (2008).
  18. D. H Kim, K. S Yang and M. Senda, "Large Eddy Simulation of Turbulent Flow in Planar Combustor", KSME, Vol. 24, No. 10, pp. 1409-1416 (2000).
  19. R. H. Chen, J. F. Driscoll, J. Kelly, M. Namaziam and R. W. Schefer, "A Comparison of Bluff-Body and Swirl-Stabilized Flames", Combust. Sci. Technol., Vol. 71, pp.197-217 (1990). https://doi.org/10.1080/00102209008951632
  20. C. K. Westbrook and F. L. Dryer, "Simplified Reaction Mechanisms for the Oxidation of Hydrocarbon Fuels in Flames", Combustion Science and Technology, Vol. 71, pp. 31-43 (1981).