Fuel and Combustion

Fuel and Combustion

Numerical simulation of the effect of the air-fuel ratio on NO emission reduction in a gas turbine combustor with a double swirler

Document Type : Original Article

Authors
Mohamadhasan Nobakhti 1
Mohamadhasan Sedghi 2
Masoud Zareh 1
1 Faculty of Mechanical Engineering, Islamic Azad University, Science and Research Branch, Tehran, Iran
2 Mechanical Engineering, Islamic Azad University, Science and Research Branch, Tehran, Iran
10.22034/jfnc.2021.269677.1262
Abstract
The purpose of this study is investigating the effect of fuel to air ratio on the flow characteristics and NO emission in a model double swirler combustion chamber. The air in this combustion chamber passes inversely through the liner. In this research, by defining the boundary conditions and producing adequate mesh, and using standard K-Ɛ model for methane fuel, combustion simulations have been performed. The simulations are performed in four different equivalence ratios, all of which are for the dilute phase of the fuel. The physics of the flow inside the chamber showed that in the higher equivalence ratios than 1, the mass flow air in entrance is not enough to keep the vortex breakdown and the stability of the flame, and thus prevents the formation of flame. By examining the vorticity and the amount of power of each vortex breakdown inside the chamber, the results showed that reducing the equivalence ratio increases the intensity of the vortex. It was found that reducing the equivalence ratio not only reduces the maximum flame temperature, but can also reduce the flame length to some extent. Finally, it was concluded that the NO production behavior is highly depend on the fluid temperature and its change graph is very similar to the temperature change diagram in the chamber, which results in a significant positive effect of decreasing the equivalence ratio on reduce the production of combustion emissions.
Keywords
effect of the air-fuel ratio
Numerical simulation 3D
double swirler combustion chamber
emission reduction
Subjects
  1. Rajaei, “Providing strategies to reduce air pollution in Tehran,” Journal of science and engineering Elites, 3, No. 1, 2019, pp. 7-29. (In Persian)
  2. S. Energy Information administration, international energy outlook 2017 overview, international energy outlook, IE2017, September 14, 2017, www.eia.gov.com, Accessed 22 March 2019.
  3. Lefebvre, D. Ballan, “Gas turbine combustion alternative fuels and emissions," third edition, CRC Press, Boca Raton, 2010.
  4. Fredrich, W. P. Jones and A. J. Marquis, “The stochastic fields method applied to a partially premixed swirl flame with wall heat transfer,” Combustion and Flame, 205, 2019, pp. 446-456.
  5. Gajan, A. Pierre, B. Alain Strzelecki, B. Platet, R. Lecourt and F. Giuliani, “Investigation of spray behavior downstream of an aeroengine injector with acoustic excitation, “Journal of propulsion and power, 23, No. 2, 2007, pp. 390-397.
  6. Fazlollahi-Ghomshi and A. Mardani, “Numerical Investigation of Reacting Flow in a Double-swirled Gas Turbine Model Combustor,” Fuel and Combustion, 9, No. 2, 2016, pp. 39-58. (in Persian)
  7. Najib, M. Nazri and M. Jafar, “Effect of varing the double radial swirler configuration on the fluid dynamic and emissions performances in a can combustor,” Jurnal Teknologi, 79, 2017, pp. 3-7.
  8. M. Elbaz, H. A. Moneib, K. M. Shebil and William L. Roberts, “Low NOX-LPG staged combustion double swirl flames,” Renewable Energy, 138, 2019, pp. 303-315.
  9. Zong, Y. Lyu, D. Guo, Li. Chengqin and T. Zhu,, “experimental and numerical study on emission characteristics of the double annular swirler under different pilot fuel ratios,” Proceedings of ASME Turbo Expo 2018 Turbomachinery Technical Conference and Exposition GT, Oslo, Norway, pp. 11-15, 2018.
  10. Zaiguo, H. Gao, Z. Zeng, J. Liu and Q. Zhu, “Generation characteristics of thermal NOx in a double-swirler annular combustor under various inlet conditions,” Energy, 200, 2020, pp. 117-187.
  11. Merlo, “Combustion characteristics of methane–oxygen enhanced air turbulent non-premixed swirling flames,” Experimental thermal and fluid science, 56, 2014, pp. 53-60.
  12. Guo, T. A. G. Langrish and D. F. Fletcher, “Simulation of Turbulent Swirl Flow in an Axisymmetric Sudden Expansion Introduction,” AIAA Journal, 39, No. 1, 2006 pp. 96-102.
  13. Pritz and M. Gabi, “Numerical Simulation of Turbulent Swirling Flows,” PAMM journal, 31, 2013, pp. 309-310
  14. Ahmadian Hosseini, M. Ghodrat, M. Moghiman and H. Pourhoseini, “Numerical study of inlet air swirl intensity effect of a Methane-Air Diffusion Flame on its combustion characteristics,” Case Studies in Thermal Engineering, 18, 2020 , pp. 390-397.
  15. Torkzadeh, F. Bolourchifard and E. Amani, “An investigation of air-swirl design criteria for gas turbine combustors through a multi-objective CFD optimization,” Fuel, 186, 2016, pp. 734–749.