While SiC/SiC CMC turbine blades have higher temperature capability than conventional Superalloy turbine blades, cooling CMC blades below their upper use temperature results in smaller strength increases than cooling Superalloy turbine blades. This paper explores the effects on aerodynamic efficiency and stresses for a notional engine where the rpm is held constant and maximum rotor blade stresses are close to 100 MPa. The notional engine is for a single aisle commercial aircraft of the 737 size, and has a two stage High Pressure Turbine(HPT). The stress constrained flow path results in blades having low aspect ratios. The annulus areas are  nearly the same for both stresses constrained blade rows . Both HPT blade rows have nearly the same flow rates. The aerodynamic efficiency and sensitivity to clearance is more critical for the second stage blade because of the higher through flow velocity in the second stage. The effect of tapering the second stage blade is examined. While the second stage blade for the notional engine does not require cooling, the first stage blade requires some cooling. Heat transfer analysis is not included in this work. However, the aerodynamic and stress analyses for the first stage blade are done for a blade shape appropriate for a cooled blade. The effect of shrouding the first stage blade on aerodynamic efficiency and stress is discussed. The feasibility of tapering an unshouded blade to increase the flow area while maintaining the same maximum stress is discussed. Aerodynamic analyses were done using the STAR-CCM+ code, and ANSYS was used for stress analysis


Design of Stress Constrained SiC/SiC Ceramic Matrix Composite Turbine Blades

Division / Sponsor:
International Gas Turbine Institute (IGTI)

Paper Proceedings: https://asmedigitalcollection.asme.org/GT/GT2020/volume/84058

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