Abstract
Future energy and transport scenarios will still rely on gas turbines for energy conversion and propulsion. Gas turbines will play a major role in energy transition and therefore gas turbine performance should be improved, and their pollutant emissions decreased. Consequently, designers must have accurate performance and emission prediction tools. Usually, pollutant emission prediction is limited to the combustion chamber as the composition at its outlet is considered to be “chemically frozen”. However, this assumption is not necessarily valid, especially with the increasing turbine inlet temperatures and operating pressures that benefit engine performance. In this work, Computational Fluid Dynamics (CFD) and Chemical Reactor Network (CRN) simulations were performed to analyse the progress of NOx and CO species through the high-pressure turbine stator. Simulations considering turbulence-chemistry interaction were performed and compared with the finite-rate chemistry approach. The results show that progression of some relevant reactions continues to take place within the turbine stator. For an estimated cruise condition, both NO and CO concentrations are predicted to increase along the stator, while for the take-off condition, NO increases and CO decreases within the stator vanes. Reaction rates and concentrations are correlated with the flow structure for the cruise condition, especially in the near-wall flow field and the blade wakes. However, at the higher operating pressure and temperature encountered during take-off, reactions seem to be dependent on the residence time rather than on the flow structures. The inclusion of turbulence-chemistry interaction significantly changes the results, while heat transfer on the blade walls is shown to have minor effects.
Highlights
The importance of reducing greenhouse gases and pollutant emissions has been pushing the transition to renewable energy
Computational Fluid Dynamics (CFD) and Chemical Reactor Network (CRN) simulations were performed to analyse the progress of NOx and CO species through the high-pressure turbine stator
The results show that progression of some relevant reactions continues to take place within the turbine stator
Summary
The importance of reducing greenhouse gases and pollutant emissions has been pushing the transition to renewable energy. The majority of models have employed the assumption that the pollutant emissions at the combustion chamber outlet remain constant and, can be considered as the output of the gas turbine [7,8,9,10]. In such models, only the chemistry inside the combustor is considered. It is worth pointing out that the investigated turbine inlet temperatures (TIT) ranged from 1459 to 1820 K at approximately 15 bars These values are relatively low when compared to the operating conditions of current aeroengines at take-off conditions
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