Curved Gas Turbine Blade Root Attachment for Stress Distribution
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Solution Overview
Problem
Existing gas turbine engine blade attachment systems face challenges in effectively managing loadings and stress distribution during operation, leading to inefficiencies and potential structural issues.
Innovation Solution
The introduction of a gas turbine engine blade with a circumferentially curved root attachment featuring a variable curvature design, which includes a first curvature in the forward portion and a second curvature in the rearward portion, allowing for sliding reception within a wheel slot, and incorporating a lobed feature to prevent radial removal, thereby balancing stresses and enhancing attachment security.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If a conventional blade attachment system is used, then the blade can be attached to the wheel, but the stress distribution is uneven leading to potential structural failure
Solution Approach 1:
The blade root attachment feature employs a curved profile with variable radius of curvature, transitioning from a first radius in the forward portion to a second radius in the rearward portion. This curvature design allows the blade root to conform to the wheel slot geometry, distributing contact stresses more uniformly across the attachment interface and preventing stress concentration that could lead to structural failure.
Solution Approach 2:
The attachment feature incorporates different radii of curvature at different locations along the blade root - a first radius for the forward portion and a second radius for the rearward portion. This localized variation in geometric properties optimizes stress distribution at each specific location, with the curvature tailored to match the local wheel slot geometry and loading conditions.
2Reliability
If a curved root attachment is used, then stress balance is improved, but the manufacturing complexity increases
Solution Approach 1:
The curved profile with variable radius is integrated into the blade casting or manufacturing process as a continuous geometric feature. By defining the root attachment geometry through mathematical curvature parameters (first radius, second radius, transition point), the design achieves complex stress-distributing geometry that can be manufactured using modern additive manufacturing or precision casting techniques, balancing manufacturing feasibility with performance requirements.
3Reliability
If the blade root is designed with variable curvature, then the attachment security is enhanced, but the device complexity increases
Solution Approach 1:
The variable curvature profile is defined by a systematic transition from a first radius of curvature to a second radius of curvature along the blade root length. This mathematical definition provides attachment security through optimized contact geometry while maintaining design simplicity through parameter-based specification rather than complex multi-component construction.
Solution Approach 2:
The root attachment geometry is characterized by varying key parameters - specifically the radius of curvature - along the length of the blade root. This parameter variation (from first radius to second radius) enables the geometry to adapt to different loading conditions and wheel slot configurations, enhancing attachment security through controlled geometric progression rather than fixed rigid forms.
Data Source
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AI summary
An airfoil member is disclosed having an attachment feature such as a fir tree or dovetail design that includes a curved profile formed from a combination of curves. In one embodiment, the curved profile can be a compound curve formed by a forward curve and a rearward curve that are joined at a point of common tangency. In another embodiment, the curved profile can include curves that do not meet at a common tangency. A cut out can be formed in the curved profile. In some forms, the cut out is formed on a pressure face of the attachment feature.