Thermodynamic Analysis of Aeroderivative Gas Turbine Engine Featuring Ceramic Matrix Composite Rotating Blades 2021-01-0033
The quest for achieving more efficient gas turbine engine systems (GTESs) has led the researchers to try getting into many new dimensions of research. Simple Brayton cycle-based GTESs were coupled with recuperators, regenerators and reheaters to avoid/recoup heat energy from being wasted and these were designated as complex GTESs. Multistage compression (multi-casing) in axial compressors and multistage (two-cylinder) expansions in turbines paved the path to optimize the plant design for greater thrust to weight ratio and greater efficiency of the GTESs. Since the increase in efficiency of any power plant is directly or indirectly related to temperatures at which the plant cycle is being operated, this thermodynamic constraint had led to the development of high temperature materials such as single crystal nickel-based superalloys. To further achieve the increment in operating temperature, different blade cooling techniques were adopted and thermal barrier coatings were applied on blades and thus, the present-day gas turbine blades are able to operate over 1500 ֯C. Today, researchers and scientists are seeking new materials that can bear higher temperatures when compared to conventional nickel-based alloys as blade material. Although ceramics are known to be able to endure extremely high temperatures, owing to their brittleness, they are not the preferred material for the manufacturing of rotating blades which are subjected to creep. On the other hand, ceramic matrix composites (CMCs) are being considered as a new alternative material which have high fracture toughness besides high temperature bearing capacity. A study of the thermodynamic analysis of an aeroderivative gas turbine engine system with CMC blades as compared to conventional directionally solidified nickel-based superalloy blades has been done. It is observed that there is a projected thermal efficiency improvement of around 3 % at a temperature of 1500 K when CMC is used as a blade material, which is significant.