A Computational Fluid Dynamics and Chemistry Model for Jet Fuel Thermal Stability

Abstract

This paper describes the development of a model for predicting the thermal decomposition rates of aviation fuels. A thermal deposition model was incorporated into FLANELS-2D, an existing computational fluid dynamics (CFD) code that solves the Reynolds-averaged conservation equations of mass, momentum, and energy. The decomposition chemistry is modeled by three global Arrhenius expressions in which the fuel decomposition was assumed to be due to an autoxidation reaction with dissolved oxygen. The deposition process was modeled by assuming that all deposit-forming species transported to the wall adhered and formed a deposit. Calibration of the model required the determination of the following parameters for a given fuel: (1) the pre-exponential constant and activation energy for the wall reaction, (2) the pre-exponential constant and activation energy for the bulk autoxidation reaction, and (3) the pre-exponential constant and activation energy for the precursor decomposition reaction. Values for these parameters were estimated using experimental data from published heated-tube experiments. Results show that the FLANELS-2D code performed well in estimating the fuel temperatures and that the three-equation chemistry model performed reasonably well in accounting for both the rate of deposition and the amount of dissolved oxygen present in the fuel at the end of the heated tube.