NUMERICAL SIMULATION OF A REACTING HYDROGEN JET IN A VITIATED CO-FLOW USING A DETAILED CHEMISTRY MODEL

The sequential combustion system in a gas turbine is composed of two complementary combustion stages in series: one premix stage followed by an auto-ignited second stage. This helps in reducing NOx significantly and gives more operation flexibility (lower loads) by redistributing the fuel between the two stages. Staged/sequential combustion is a state-of-the-art method to provide operation flexibility and reduced emissions in gas turbines. A key requisite for such a model is the accurate determination of the flame location to predict emissions, flame dynamics, and temperature distribution. The numerical simulations of such combustion systems must accurately capture auto-ignition and flame propagation to predict the flame position and shape. In this work, the hydrogen lifted flames are simulated using a 2-equation LES model with detailed chemistry and Adaptive Mesh Refinement (AMR). The sensitivity of the flame lift-off height to the co-flow temperature and velocity fluctuations at the inlet is studied. The numerical results of the so-called Cabra H2 flame are validated against experimental [1] and numerical results in the literature [2-8].