Mechanical Design and Analysis of Ceramic Stator Blades for Gas Turbine Stage

Abstract

The demand for higher power, better thermal efficiencies and lower weight gas turbines engines, calls for the research in the area of high temperature resistant materials to increase the TET (Turbine entry Temperatures). Research programs conducted so far by GARETT/DARPA indicated that replacing certain metal hot section parts with ceramics in gas turbine could improve engine output power, thermal efficiency with reduced SFC. Ceramic materials are better viable candidates for modern day gas turbine engine needs, because of their high temperature durability, lower specific weight, and high resistance to hot corrosion. Ceramics, especially silicon based carbides and nitrides (SiC& Si3N4) can withstand temperatures up to 1300°C. This paper presents a mechanical design and non-linear axi-symmetric steady state thermo-mechanical finite element analysis of stator (nozzle guide vane) blades of HP turbine with Si3N4 (Silicon Nitride).Mechanical design of stator blade is carried out using Si3N4 to replace existing metal stator blade of HP turbine. Designed stator blade has been subjected to steady state thermo-mechanical finite element analysis to validate the design. The stress distributions, concentration are evaluated for failure and factor of safety criteria. The life limiting stress concentrations in the critical zones of stator are evaluated aiming at a probability of success based on “Weakest Link Theory” and Mohr's-Coulomb Theory. The designed ceramic stator blade eliminates cooling requirements and weight of the blade has been reduced by 63%.