Review of propane-air chemical kinetic mechanisms for a unique jet propulsion application

Abstract A review of available propane-air chemical kinetic mechanisms was undertaken to determine how best to computationally model the combustion of propane and air at standard sea level conditions inside a unique ramjet engine. The included review comprises a set of 35 distinct mechanisms covering more than 30 years of work intended to model different aspects of propane-air chemistry. A selection of the available mechanisms was compared using a calibrated and validated zero-dimensional constant volume simulation with mixture ignition delay as the primary metric. The most accurate version across a range of equivalence ratios and temperatures was the San Diego mechanism due to its continual evolution through the adjustment of the reactions forming hydroxyl radicals to match ignition data. Subsequently, a reduced form of this mechanism was generated for three-dimensional Computational Fluid Dynamics (CFD) simulations by removing reactions that did not affect the ignition delay at the 1 ms level. A one-dimensional variable property reacting flow shock tube simulation illustrated that this reduced mechanism did lose some accuracy in predicting the ignition delay for a unique set of data. However, it worked effectively in conjunction with the CFD model to predict the unique operational characteristics of the acoustically-pressurized ramjet engine.