Simulation of a toroidal jet-stirred combustor using a partially stirred reactor model with detailed kinetic mechanisms

Abstract

The detailed chemistry in a jet-stirred laboratory combustor has been computed with a partially stirred reactor (PaSR) model that uses interaction by exchange with the mean as a turbulent moment closure to simulate finite time micro-mixing. Ideal macro-mixing is assumed as characterized by an exponential residence time distribution. Local conditions are relaxed toward the mean at a rate defined by the mixing frequency that is a ratio of the turbulent dissipation to the turbulent mixing energy. The solution technique approximates mean conditions, and solves the deterministic model to refine the approximation, and eventually converge on a solution. The approximation and convergence technique compared favorably with the Monte Carlo modeling calculations presented in the literature, while using, on average, less than 1/100th of the CPU time. The comparison of PaSR model predictions to literature experimental data from a toroidal jet-stirred laboratory combustor operating in both fuel-lean and fuel-rich conditions also showed reasonable agreement with data. Moreover, the PaSR proved valuable as a research tool. It provided an indication of the sensitivity of reactor kinetics to the effects of micro-mixing delay, and predicted temperature and species distributions, while using detailed thermo-kinetic mechanisms. These features, which are beyond the scope of the perfectly stirred reactor (PSR) model, are provided within reasonable computational times.