Date of Award
Mechanical, Automotive, and Materials Engineering
This work reports on the premixed propane-air flame propagation in a long length (1.8 m) straight rectangular (51\times25 mm) duct. The mixture is assumed to be homogenous inside of the duct. Different equivalence ratios are examined. Two cases of fully opened and fully closed end outlet conditions are considered here. The flame behavior along with its propagation in the duct including initial stage of flame growing after the ignition, flame finger shape, flame-wall touch, flame flatten profile, tulip flame formation, tulip flame lips collapsing, and possible subsequent inversion/inversions are discussed. At each step, the flame-feeding flow interchangeable effect is explored using numerical simulations. Furthermore, the physical mechanisms behind the tulip flame and the subsequent inversion/inversions (especially the first flame inversion in opened end outlet case) are illustrated. Also, similarities and differences between these two phenomena are studied. In terms of the numerical method, two CFD software packages, Star CCM+ and OpenFOAM have been utilized. The available EBU (Eddy Break-Up) combustion model in Star CCM+ code, while its reaction rate is limited to Arrhenius reaction rate, is employed (semi-laminar model). The XiFoam model which is the embedded turbulent combustion model in OpenFOAM is also used. Other famous numerical combustion models such as TFC (turbulent model), FSC (it can capture both laminar and turbulent conditions simultaneously), and TFM (laminar and turbulent combustion model) are made based on the XiFoam model. Also, these models (XiFoam, TFCFoam, FSCFoam, and TFMFoam) are coupled with adaptive mesh library in order to make the finer mesh at the flame location (3D geometries). The new models are named: XiDymFoam, TFCDymFoam, FSCDymFoam, and TFMDymFoam. Moreover, further modifications are made to make these new models ready for 2D cases. The capability of these models for simulation of premixed propane-air flame propagation in the duct has been examined. The analytical works published by other research groups were also modified for the rectangular channel, and the results employed as another datum for validation of experimental and numerical results.
Movahedi, Zakaria, "An Investigation of Premixed Flame Propagation in a Straight Rectangular Duct" (2017). Electronic Theses and Dissertations. 7384.
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