Computational Fluid Dynamics Modeling of Jet-Stirred Reactors

The combustion of biofuels and petroleum-derived hydrocarbons provide for ~99% of transportation energy in the U.S. and demand is not projected to decline significantly either domestically or globally. In practical applications, combustion merges detailed chemistry with fluid dynamics, the understanding of which is paramount to developing computational models for the design of next-generation engines that afford high-efficiency operation and decreased emissions. To mitigate the complexities imposed from the inherent coupling of chemical reactions with fluid dynamics, gas-phase chemical kinetics analysis requires experiments that are conducted under conditions of constant temperature and pressure. Under dilute conditions, a jet-stirred reactor (JSR) provides a means for using turbulence to create thermal homogeneity of reacting gases on timescales shorter than chemical reactions occur. However, the extent to which homogeneity is ensured depends on the conditions of the experiment and the parameters that affect the underlying physics, such as turbulence levels and rates of diffusion. In the present work, a computational fluid dynamics (CFD) model is developed using Ansys Fluent for simulating fluid flow within a JSR. The primary aim of the model is to examine the thermal homogeneity of N2 flow within a conventional JSR. In particular, the CFD simulations are conducted in order to evaluate the effects of experimental parameters on turbulence and concomitant spatial temperature gradients within the JSR. The parameters include the initial temperature of the N2 flow at 300 K, and the following boundary conditions: reactor temperature 500 K, and 1 atm pressure.