Gas Turbine Blade Lateral Surface Contour for Stress Reduction
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Solution Overview
Problem
Stiffness jumps between thin blade airfoils and solid disks in gas turbines lead to undesirable stress clusters, which are currently mitigated by fillets or transition radii that can adversely affect aerodynamics.
Innovation Solution
A blade arrangement with a radially inner lateral surface featuring a curved contour in meridian sections, including intersection points and an intermediate point, where the contour sections are positioned on opposite sides of a best-fit line, optimizing distances to reduce stress peaks and improve aerodynamics.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Strength
If fillets or transition radii are used to reduce stress clusters, then stress peaks are reduced, but aerodynamic performance deteriorates
Solution Approach 1:
The patent applies different geometric characteristics to different regions of the blade arrangement. The lateral surface features a curved contour with specific radius ratios in different zones: a first radius at the front edge, a second radius at the rear edge, and a third radius in the intermediate region. This local differentiation allows stress reduction where needed while preserving aerodynamic contours in critical flow regions.
Solution Approach 2:
The invention employs curved transitions instead of sharp corners or simple fillets. The lateral surface contains a curved contour with multiple radii of curvature that smoothly transition between the blade airfoil and the disk body. This curvature approach reduces stress concentration while maintaining aerodynamic performance by avoiding abrupt geometric changes.
2Ease of manufacture
If the lateral surface contour is simplified, then manufacturing is easier, but stress peak reduction effectiveness decreases
Solution Approach 1:
The patent defines the curved contour through specific parameter relationships: radius ratios between the first, second, and third radii; position ratios of where these radii are applied along the contour; and curvature transition parameters. By controlling these parameters within specified ranges, the invention achieves effective stress reduction while maintaining manufacturability through systematic geometric definition rather than complex free-form surfaces.
Data Source
AI summary
A curved contour of the lateral surface of a blade arrangement includes in at least one meridian section on mutually opposite sides of a blade airfoil an intersection point that is closer to the blade airfoil front edge, and an intersection point that is closer to the blade airfoil rear edge, and a best-fit line of least square distances from the curved contour. The curved contour includes first and/or the second contour section which meet specified conditions.