Effect of Ceramic Matrix Composites on the Thermal Efficiency of a Power Generation Turbine

Abstract

Ceramic Matrix Composites (CMCs) offer higher allowable temperatures and reduced weight, making them an attractive prospect for parts in the hot section of a gas turbine engine. As CMCs are increasingly adapted into aero and land-based engines, there is a need to quantify the performance increase based on potential for reduced cooling and increased firing temperatures. In this work, two hot section components – the first stage turbine vane and tip shroud (outer casing above the blade) - of a mid-sized power generation engine were modeled. Informed approximations about part geometry and cooling architectures were made to determine cooling requirements of each part. Thermal boundary conditions for the turbine tip shroud and turbine vane were generated as a function of coolant mass flow rate using data from literature and applied to a 2D finite element analysis model to determine maximum temperatures for both metallic and ceramic materials. A gas turbine cycle model was developed to simulate the performance of a mid-sized power generation turbine, and used to determine increase in efficiency due to reduction in cooling requirement for the CMC part. Potential reduction in chargeable cooling seen for the tip shroud was between 0.09% and 0.4% of the compressor mass flow rate, which corresponds to an increase in thermal efficiency between 0.11% and 0.45%. A similar analysis of the turbine vane resulted in a cooling reduction of 10.71% at the maximum thermal load considered which corresponds to a 3.4% increase in thermal efficiency.