Non-reacting Numerical Simulation of Axisymmetric Trapped Vortex Combustor

Authors: Heval Serhat Uluk, Sam M. Dakka, Kuldeep Singh, Richard Jefferson-Loveday

Abstract:

This paper will focus on the suitability of a trapped vortex combustor as a candidate for gas turbine combustor objectives to minimize pressure drop across the combustor and investigate aerodynamic performance. Non-reacting simulation of axisymmetric cavity trapped vortex combustors was run to investigate the pressure drop for various cavity aspect ratios of 0.3, 0.6 and 1 and for air mass flow rates of 14 m/s, 28 m/s and 42 m/s. A numerical study of an axisymmetric trapped vortex combustor was carried out by using two-dimensional and three-dimensional computational domains. A comparison study was conducted between Reynolds Averaged Navier Stokes (RANS) k-ε Realizable with enhanced wall treatment and RANS k-ω Shear Stress Transport (SST) models to find the most suitable turbulence model. It was found that the k-ω SST model gives relatively close results to experimental outcomes. The numerical results were validated and showed good agreement with the experimental data. Pressure drop rises with increasing air mass flow rate, and the lowest pressure drop was observed at 0.6 cavity aspect ratio for all air mass flow rates tested, which agrees with the experimental outcome. A mixing enhancement study showed that 30-degree angle air injectors provide improved fuel-air mixing.

Keywords: Aerodynamic, Computational Fluid Dynamics, Propulsion, Trapped Vortex Combustor.

References:

[1] K.-Y. Hsu, L. P. Goss, D. D. Trump, and W. M. Roquemore, “Performance of a Trapped-Vortex Combustor.”
[2] A. H. Lefebvre and D. R. Ballal, “GAS Turbine Combustion Third Edition Alternative Fuels and Emissions.”
[3] P. K. Ezhil Kumar and D. P. Mishra, “Combustion noise characteristics of an experimental 2D trapped vortex combustor,” Aerosp Sci Technol, vol. 43, pp. 388–394, Jun. 2015, doi: 10.1016/j.ast.2015.03.014.
[4] K. Y. Hsu, L. P. Goss, and W. M. Roquemore, “Characteristics of a trapped-vortex combustor,” J Propuls Power, vol. 14, no. 1, pp. 57–65, 1998, doi: 10.2514/2.5266.
[5] C. Ghenai, K. Zbeeb, and I. Janajreh, “Combustion of alternative fuels in vortex trapped combustor,” Energy Convers Manag, vol. 65, pp. 819–828, Jan. 2013, doi: 10.1016/j.enconman.2012.03.012.
[6] A. Singhal and R. V Ravikrishna, “Single cavity trapped vortex combustor dynamics-Part-1: Experiments.”
[7] R. C. Hendricks et al., “Experimental and Computational Study of Trapped Vortex Combustor Sector Rig with High-Speed Diffuser Flow,” 2001.
[8] W. A. Mair, “The Effect of a Rear-Mounted Disc on the Drag of a Blunt-Based Body of Revolution,” Aeronautical Quarterly, vol. 16, no. 4, pp. 350–360, Nov. 1965, doi: 10.1017/s0001925900003589.
[9] B. H. Little and R. R. Whipkey, “Locked Vortex Afterbodies,” J Aircr, vol. 16, no. 5, pp. 289–295, 1979, doi: 10.2514/3.58522.
[10] “Ansys Fluent Theory Guide,” 2022. Online. Available: http://www.ansys.com
[11] P. K. Ezhil Kumar and D. P. Mishra, “Numerical simulation of cavity flow structure in an axisymmetric trapped vortex combustor,” Aerosp Sci Technol, vol. 21, no. 1, pp. 16–23, Sep. 2012, doi: 10.1016/j.ast.2011.04.007.
[12] I. B. Celik and J. Li, “Assessment of numerical uncertainty for the calculations of turbulent tow over a backward-facing step,” International Journal for Numerical Methods in Fluids Int. J. Numer. Meth. Fluids, vol. 49, pp. 1015–1031, 2005, doi: 10.1002//d.1040.