Robust aero-thermal design of high pressure turbines at uncertain exit conditions of low-emission combustion systems

A key challenge in the development of novel, low-emission combustion systems in jet engines is the analysis of combustor turbine interaction. The exit conditions of the combustor are accounted for in the design of the first HPT stage in order to increase the efficiency of the system. Due to the extreme temperatures in jet engine combustors the knowledge of these conditions is subject to large uncertainties. The goal of this work is the development of a method to account for these uncertainties in design. This shall enable the development of robust components that do not fail if conditions deviate from the design point. A major component of the method is a model that generates 2D flow profiles of modern lean burn combustors based on a parameter set. These are used as boundary condition of a 3D flow simulation of the HPT. Stochastic deviations of the input parameters can thus be accounted for. The developed process chain which couples parameters of HPT inlet conditions with performance parameters of the engine is analysed by means of statistical methods for UQ. The model is able to reproduce both, conditions of a test rig as well as those in real engines. Strong swirl at the combustor exit interacts with the first row of stator vanes of the HPT. Secondary flows in the vane passage are influenced and additional structures are induced by the inlet swirl. A significant correlation between the position of the inlet swirl core and the position of the induced structures is identified. The relation transforms variations in the position of inlet swirl to variations in the local thermal load of the vanes and hub end wall and thus of the HPT’s life time. Uncertainties in thermal efficiency result mainly from uncertainties in the position of hot streaks at HPT inlet.