Abstract
A promising concept to further improve the efficiency of aircraft gas turbines while reducing pollutant emissions is the injection of water steam in the combustor. This approach, known as Water-Enhanced Turbofan (WET) concept, involves that water is recovered from the exhaust, compressed in a liquid state and finally fed to the combustion chamber after passing through a steam generator. In the present work, we investigate the suitability of the flamelet-generated-manifold method to model turbulent combustion under WET conditions, i.e., with high steam loads. As a test case, we use a premixed swirl-stabilized methane-air flame for which experimental reference data are available for dry conditions. The numerical results are in good agreement with both a finite-rate reference simulation as well as with experimental data for velocity and OH*-chemiluminescence. We also observe a significant impact of the steam content in the unburnt gas on the flame shape. In particular, increasing the water-gas-ratio leads to an elongation of the flame. At the same time, the reaction zone becomes wider, leading to reduced heat release maxima. As a consequence, a more homogeneous temperature distribution is observed, which leads to a reduction of NOx formation.
