Stator Vane Platform Reinforcement for Stress Mitigation
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Solution Overview
Problem
The existing designs of gas turbine engine stator vanes face stress concentration issues at the intersection of the outer platform and rail due to axial pressure-induced loads, particularly because of the constant fillet radius and thin gussets, which are insufficient in managing compressive stress and thermal loads.
Innovation Solution
A reinforcement with variable thickness is introduced in the form of a fillet or hooks, positioned centrally between the airfoils, extending radially from the gas path side to the non-gas path side, forming a pocket that joins the platform and rail, with a width between 10%-50% of the rail's width and thickness greater than the non-reinforced regions to mitigate stress concentrations.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Ease of manufacture
If a constant fillet radius and thin gussets are used at the intersection of the outer platform and rail, then the device complexity is reduced and ease of manufacture is improved, but stress concentration increases and structural strength deteriorates under axial pressure-induced loads
Solution Approach 1:
The reinforcement feature introduces variable thickness in the circumferential direction, creating a locally thickened region at the intersection of the outer platform and rail. This local quality change provides additional stress distribution capability precisely where compressive stresses are concentrated, while maintaining constant thickness in non-critical regions to preserve manufacturing simplicity.
Solution Approach 2:
The invention changes the thickness parameter of the reinforcement feature from constant to variable in the circumferential direction. The thickened portion is strategically positioned to provide enhanced strength at the stress concentration zone, while the thickness transitions to match the base structure in non-critical areas, optimizing both strength and manufacturability.
2Manufacturing precision
If discrete thin gussets with constant fillet radius are used, then manufacturing precision requirements are reduced, but stress distribution capability deteriorates and reliability decreases under thermal and axial loads
Solution Approach 1:
The reinforcement feature provides localized thickening at the critical intersection region, improving stress distribution and structural reliability where it is most needed. The variable thickness design allows the structure to better handle thermal and axial loads without imposing stringent manufacturing precision requirements across the entire component.
Solution Approach 2:
The thickened reinforcement feature acts as a preemptive structural enhancement, providing additional material and stress distribution capacity before thermal and axial loads are applied. This beforehand cushioning prevents stress concentration from developing into failure, thereby improving reliability under expected operating conditions.
3Strength
If the reinforcement has variable thickness in the circumferential direction, then stress distribution improves and structural strength increases, but device complexity increases and manufacturing difficulty worsens
Solution Approach 1:
The variable thickness reinforcement introduces complexity only in the specific region where it is needed for stress distribution, while the rest of the structure maintains simple constant thickness. This localized approach minimizes overall device complexity while achieving the strength benefits in critical areas.
Solution Approach 2:
Instead of making the entire reinforcement feature uniformly thick (excessive action), the invention applies variable thickness only in the circumferential direction where stress concentration occurs, leaving other dimensions with constant thickness. This partial application of variable thickness provides the necessary strength improvement without proportionally increasing device complexity.
Data Source
AI summary
A stator vane for a gas turbine engine includes a first platform and a second platform radially spaced apart from one another. The first and second airfoils are circumferentially spaced from one another and interconnect the first and second platforms. The first platform has a gas path side facing the airfoils and a non-gas path side opposite the gas path side. A circumferentially extending rail provided on the first platform extends radially outward from the gas path side to the non-gas path side to form a pocket on the non-gas path side between the first platform and the rail. A reinforcement is arranged in the pocket and joins the first platform and the rail. The reinforcement includes a variable thickness in the circumferential direction and is arranged generally centrally between the first and second airfoils.