UBC Theses and Dissertations
Implementation of conditional source-term estimation for the prediction of methane ignition Blair, C. W.
'Implementation of Conditional Source-term Estimation for the Prediction of Methane Ignition' The Laminar Flamelet Decomposition approach to Conditional Source-term Estimation is a recent development in combustion modeling that approximates the conditional averages of scalars as linear combinations of basis functions obtained from a library of unsteady solutions to the classical flamelet equations. Then an integral equation for a single scalar is inverted and solved for the weighting function of the basis functions. This weighting function is then used to obtain closure for the chemical source terms in the transport equations. Many parameters affect the solution of the Conditional Source-term Estimation method including the solution technique for inverting the integral equation; the number of solutions in the flamelet library; and the scalar used for the integral equation. The first part of this research investigated these parameters to optimize the solution for the Conditional Source-term Estimation. This is accomplished in the a priori sense by comparison to Direct Numerical Simulations of a simple turbulent flame. The second part of this work implemented Conditional Source-term Estimation into the commercially available multi-dimensional combustion software, KIVA-II by replacing the existing ignition mechanism. The model was used to predict the ignition of methane for different initial temperatures and compared to experimental results. The predicted ignition delay times were shorter than the experimental results but exhibited similar trends.
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