| Flame and combustion phenomena have been investigated for more than two centuries. With the progress in computer hardware and software in the 20th century, theories, approaches, techniques and applications in the field of numerical simulation of combustion have emerged dramatically and grown rapidly. This thesis presents theoretical and numerical studies of thermodynamics and kinetics in chemical reaction and their applications to simulation of reacting flow fields based on two-dimensional unstructured grids.Firstly, the criterion for chemical equilibrium, on the basis of the first law and second law of thermodynamics, is presented. For a constant temperature, constant volume process, the Helmholtz Free Energy attains minimum at equilibrium. Similar conclusion holds for the Gibbs Free Energy for a constant temperature, constant pressure process. Through the application of the equilibrium criterion, a numerical treatment is proposed to solve the equilibrium parameters of a multi-species system, and applied to calculate the CJ detonation parameters.Governing equations of the species concentration from the chemical kinetics and corresponding numerical treatment are discussed extensively. With existing detail chemical reaction mechanisms, such as hydrogen oxidation mechanism as well as methane oxidation mechanism, the reacting process of hydrogen/oxygen and methane/air system are calculated and validated against equilibrium solutions.At last, a numerical method is proposed to simulate chemical reacting flow based on unstructured meshes and the finite volume method, Godunov scheme, HLLC Riemann solver, and the time-splitting method are employed to numerically calculate such reacting flows as detonation propagation, sub- and super-sonic diffusion flames. Good agreement between numerical predictions and experimental data indicates that the numerical treatment proposed in the thesis is feasible for simulating multi-species reacting flows. |
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