Cooling system optimization of combustor liners

The optimization process of liner cooling system of industrial annular combustor is performed, since the early phase of design, by means of an innovative in house code, performing a one-dimensional conjugate aero-thermal-strain analysis. The liner cold side heat transfer coefficients in a turbulated forced convection region are iteratively computed updating metal and air temperatures and the deformed geometry of coolant passages from results of a heat balance. Coolant passages, in between the deformed surfaces of liner and baffle, influence the local velocity, changing heat transfer coefficients and coolant pressure losses. The liner and baffle strain computation has been validated comparing the code results with the ones obtained by a detailed finite element model. The correlations embedded in the code are calibrated thanks to a thermal and pressure data matching performed with experimental measurements acquired in a full annular rig test campaign. The optimization process, maintaining the same coolant pressure losses, minimizes the axial metal temperature gradients distribution, reducing the thermal induced stresses: the resulting liners durability can be significantly enhanced, without penalizing engine performance.