Rotor Disk Slot Bulge Design for Crack Resistance
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Solution Overview
Problem
Turbine blade slots in rotor disks often develop cracks during servicing, necessitating costly repairs such as brazing or welding, or the installation of lighter blades.
Innovation Solution
The slot design of the rotor disk features upper indentations with bulges that extend from the indentation, creating a cavity that helps distribute radial forces and potentially reduces stress concentrations that could lead to cracking.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If conventional slot design is used, then manufacturing is simple, but cracks form in the slots during servicing
Solution Approach 1:
The patent applies local quality by introducing bulges at specific locations within the slot (particularly at the upper indentation) to create localized stress redistribution zones. This modifies only the critical areas where cracks typically initiate, rather than redesigning the entire slot structure, thereby improving crack resistance while maintaining overall structural simplicity
Solution Approach 2:
The patent employs curvature by designing bulges with rounded contours instead of sharp edges within the slot structure. These curved features help distribute stress more evenly and prevent stress concentration at sharp corners, which is a primary cause of crack initiation. The spheroidal geometry of the bulges directly addresses the crack formation problem
2Reliability
If slots are designed with higher stress distribution, then crack formation is reduced, but manufacturing complexity increases
Solution Approach 1:
The patent applies preliminary action by incorporating stress-distributing bulges into the slot design during the manufacturing stage, before any cracks can form. This preventive measure ensures that stress is properly distributed from the beginning of service, eliminating the need for later repairs or blade replacements and simplifying the overall maintenance process
Solution Approach 2:
The patent utilizes parameter changes by modifying the geometric parameters of the slot (adding bulges with specific dimensions and positions) to optimize stress distribution. These parameter adjustments are made within standard manufacturing capabilities, balancing improved slot integrity with ease of fabrication
Data Source
AI summary
A rotor disk includes a slot for receiving a blade foot of a turbine blade, wherein the slot has multiple indentations along the longitudinal axis of the slot for protrusions of the blade foot and so as to complement said protrusions. An axial bulging is provided within the at least one projection, in particular multiple projections of a slot have a bulging.