Analysis of the influence of the geometric form at the outlet of the injector on the protection of a gas turbine combustor liner

Numerical investigations of a real scale gas turbine combustor operating under industrial conditions were conducted in this paper. The studied combustion chamber has a high degree of geometrical complexity related to the injection system as well as the cooling system based on a big distribution of small holes (about 3390 holes) bored on the liner walls. The main aim of this study was to investigate the effect of the type of widening at the outlet of the injector on the distribution of the temperature of the walls of the flame tube. In order to do this, two cases were considered: the first case corresponds to a sudden widening and the second case corresponds to a conical widening by the addition of a conical divergent piece at the outlet of the injection system. The calculations were carried out using the industrial CFD code Ansys FLUENT. The difference between the maximum temperatures reached shows the important role of this piece in the protection of the cap of the flame tube. The results showed that the addition of the conical divergent piece permits to considerably reduce the maximum temperature of the liner cap. In fact, the temperature decrease is of the order of 300 degrees C near the injector and more than 800 degrees C elsewhere, which corresponds to a reduction of 17% and 50% respectively.