Turbomachine Rotor Blade Variable Transition Radius
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Solution Overview
Problem
Existing rotor blades in steam and gas turbines face challenges in optimizing mechanical loading capacity, stress distribution, and resonance behavior, often leading to costly manufacturing processes, material property complexities, and potential for crack-prone edges or flow losses due to added ribs or multiple materials.
Innovation Solution
A rotor blade design featuring a platform overhang with a variable transition radius allows for targeted adjustment of vibrational behavior and stress progressions, eliminating stress concentration and weight imbalances, while maintaining a single material composition and simplifying manufacturing by avoiding post-processing and ribs.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If a pocket for accommodating different material is provided on the blade tip side, then the weight distribution and vibrational behavior are improved, but crack-prone edges and transitions develop requiring expensive manufacturing
Solution Approach 1:
The invention extracts the harmful pocket structure from the blade design and replaces it with a variable transition radius on the platform overhang. This eliminates the need for separate material pockets while maintaining the beneficial vibrational characteristics through geometric optimization alone.
Solution Approach 2:
The variable transition radius applies local geometric variation specifically at the platform overhang transition area, concentrating the stress distribution optimization where it is most needed without requiring material changes throughout the entire blade structure.
2Reliability
If ribs are provided on platform overhangs to reduce vibrations, then vibrational behavior is improved, but excess weight is added and flow losses increase
Solution Approach 1:
The invention uses a variable transition radius (curved geometry) at the platform overhang to achieve vibrational control and stress distribution optimization, replacing the need for straight ribs while maintaining smooth flow paths without turbulence-inducing edges.
Solution Approach 2:
The transition radius is varied as a continuous parameter along the platform overhang, allowing optimization of both vibrational characteristics and flow properties simultaneously, unlike fixed-geometry ribs that create flow separation and turbulence.
3Reliability
If ribs are provided on platform overhangs to reduce vibrations, then vibrational behavior is improved, but excess weight is added leading to cracks in the blade root
Solution Approach 1:
The variable transition radius uses curved geometric progression to distribute mass more effectively, achieving vibrational control through optimized mass distribution rather than adding concentrated rib structures that increase overall weight and create stress concentrations.
4Strength
If multiple materials are used in the rotor blade, then mechanical loading capacity is improved, but material property definition and manufacturing complexity increase
Solution Approach 1:
The variable transition radius provides locally optimized stress distribution and vibrational characteristics through geometric variation alone, eliminating the need for multiple materials with different properties while maintaining enhanced mechanical performance in critical areas.
Data Source
AI summary
The invention relates to a blade (2) of a turbomachine, in particular a rotor blade of a gas turbine, which has a variable transition radius (Rv1) in the vicinity of at least one platform overhang (16), and to a turbomachine having at least one such blade (2).