This title appears in the Scientific Report :
2017
Mathematical Modeling & Simulation of Pyrolysis & Flame Spread in OpenFOAM
Mathematical Modeling & Simulation of Pyrolysis & Flame Spread in OpenFOAM
This thesis investigates the numerical modeling and simulation of pyrolysis and flame spread using OpenFOAM. For the purpose of simulation, the large eddy simulation solver FireFOAM developed by FM Global was used. A major portion of the thesis involves the coupling of mass and energy transfer acros...
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Personal Name(s): | Vinayak, Ashish (Corresponding author) |
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Contributing Institute: |
Jülich Supercomputing Center; JSC |
Imprint: |
2017
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Physical Description: |
60 p. |
Dissertation Note: |
Masterarbeit, Bergische Universität Wuppertal, 2017 |
Document Type: |
Master Thesis |
Research Program: |
Computational Science and Mathematical Methods |
Publikationsportal JuSER |
This thesis investigates the numerical modeling and simulation of pyrolysis and flame spread using OpenFOAM. For the purpose of simulation, the large eddy simulation solver FireFOAM developed by FM Global was used. A major portion of the thesis involves the coupling of mass and energy transfer across the fluid and material domains, to achieve radiant heating of Polymethyl methacrylate (PMMA), which serves as the dominant mode of energy transfer during the flaming combustion of PMMA. Ongoing research at Bergische Universität Wuppertal (BUW) with Cone Calorimeter-like experiments (ISO-17554) is used to validate the results of the simulation.The investigation consists of 5 setups, wherein simulated setup consists of a horizontal and vertical placed PMMA blocks, that are heated using a fixed incident flux at various angles. In the initial stage, simulations were carried out in an uncoupled manner to achieve convergence in either regions of the mesh. Increasing in complexity, several boundary conditions were developed, to realize the idea of mass, momentum and energy transfer across the interface boundary.The thesis provides a method to obtain mass loss rate (MLR) of any arbitrary material when it is subject to radiant heat at its surface. The addition of radiation to an already burning material increases the mass loss rate (MLR) of the material. This is demonstrated through the development of a new boundary condition that applies a fixed radiant heat with the addition of a surface radiation source term from the flame. For obtaining a proof of concept, a minimum residual optimization was carried out for three parameters, namely, heat of volatilization, the pre-exponential factor and the activation energy ratio, the latter of which are the Arrhenius parameters. The optimization of single parameters shows that the activation energy ratio and heat of volatilization is a highly sensitive parameters, greatly affecting the magnitude of mass loss rate of the material. For the first simulation, on which the optimization was carried out, the simulated results show good agreement with the experimentally obtained values. For the remaining 4 simulations, the mass loss rate and flame spread velocity were computed. The mass loss rates show parallel gradients i.e they are shifted in time to the experimentally obtained values. This in turn causes the predicted values of flame spread velocity to be higher than the experimental results. Thus, the idea of using one set of optimized parameters for all simulations could not be confirmed. It would therefore be possible to obtain exact curves for the other simulations by further optimization. |