Thermodynamic Potential of Aluminum Oxide Ceramic Matrix Composite Application in the 1st Stage Vanes of Industrial Gas Turbines

Ceramic matrix composites (CMC) for application in gas turbine hot sections have been a topic of research for the last three decades. Until now, CMCs have found only limited use due to their mechanical limitations, economic factors and availability of the base material Silicon Carbide. Currently, a new manufacturing process combining 3D braiding technology with slurry die casting based on aluminum oxide is being developed within a collaborative research project. It aims to create CMCs that can withstand the thermal and mechanical stresses while having a longer life cycle than conventional nickel-based super alloys used in industrial gas turbines. One task within the collaborative research project is to derive the impact of the application of the new type CMC on the gas turbine thermal cycle behavior. Thus, the objective of this paper is to show the potential of the 1st stage vane made of the new 3D braided Al2O3-CMC in terms of thermodynamic efficiency enhancement by cooling air reduction. The first stage vane of a generic 30 MW industrial gas turbine is analyzed as reference case by means of aero- (CFD), heat transfer (CHT) and mechanical (FEA) simulations at different cooling air mass flows in case of conventional vane material and the new type CMC in comparison. A thermodynamic model of the gas turbine is then used to show the implications on the cycle and its efficiency in case the material of the first stage vanes is changed to the new type CMC. The results show that the positive potential in thermal efficiency depends significantly on the further usage of the cooling passing through the hollow CMC vane.