Prediction of emissions from combustion systems using 0D and 1D reacting flow models

Abstract

Emission prediction is a complex problem involving the coupling between the flow field and chemistry. Most of the time CFD is the preferred modeling approach, yielding predictions with varying degrees of accuracy. But because of a high computational cost, CFD investigations are often limited to the use of reduced chemical mechanisms. In this work the specific features of chemical reactor networks are exploited to build a fast and reliable emission estimator. The main advantage of this modeling approach is a much lower computational cost than CFD, hence offering the potential for relatively fast predictions while allowing the use of detailed chemistry. This methodology has been applied to three different combustion systems, with mixed results. It may not be the most suitable modeling technique to obtain emissions from a lifted jet flame, but a successful estimator has been designed for flameless furnaces. It is based solely on analytical sub–models, giving it the potential to predict the emissions from any type of flameless furnace installation. For three different experimental setups, the correct trends were reproduced as well as the right order of magnitude for ??x and ?? emissions, if not within experimental measurements uncertainty. Finally the emissions from a lean-premixed gas turbine combustor burning cryogenic fuel have been successfully modeled and this investigation has brought out the major sensitivities of this system. Lastly, despite some promising results, several developments have been suggested to improve the accuracy and stability of the flameless furnace estimator. The combustor estimator, for one, can be used as basis to investigate the behavior of the more comprehensive hybrid combustion system it has originally been designed for: the dual combustion chamber of the AHEAD hybrid engine (Advanced Hybrid Engines for Aircraft Development).