75th Annual Meeting of the APS Division of Fluid Dynamics (November 20, 2022 — November 22, 2022)

V0053: Visualization of Ignition Kernels in Auto-Igniting Methanol Spray Flames using Dynamic Mode Decomposition

Authors

• Bharat Bhatia, Department of Aerospace Engg., IIT Kanpur
• Ashoke De, Department of Aerospace Engg., IIT Kanpur
• Dirk Roekaerts, Dept. Of Process and Energy, Delft University of Technology
• Assaad R. Masri, School of Aerospace, Mechanical, and Mechatronic Engineering, The University of Sydney

DOI: https://doi.org/10.1103/APS.DFD.2022.GFM.V0053

In the lifted flames, the ignition kernel plays an important role in deciding the lift-off height and other flame characteristics. The ignition kernel formation diffusion/partially premixed flames depend on the flow structure and the mixing of fuel-oxidizer. Here, the Dynamic Mode Decomposition (DMD) is used to visualize the vortex structures responsible for the formation of the dominant ignition kernel (and flame structure) at the flame base. The OH mass fraction and velocity fields are used to visualize flame and vortex structures, respectively. The DMD provides the dominant frequencies of the OH field and corresponding to these frequencies, the modes of velocity field are identified and reconstructed. In this case, the reconstructed velocity field of the DMD modes is found to be the streamwise vortices formed in the braid region of the dilute methanol spray flame. Note that the vortex structures are visualized using Q-criterion.