Turbine Vane Trailing Edge Cutback Design
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Solution Overview
Problem
The trailing edge of turbine vanes in gas turbines is structurally vulnerable due to high thermal stress, leading to a high risk of breakage and cracking, as it is the thinnest part of the airfoil and experiences significant stress concentration.
Innovation Solution
The introduction of cutbacks on both the pressure and suction surfaces of the trailing edge, perpendicular to the radial direction, which are optionally connected to extended holes, provides flexibility and alleviates stress concentration, delaying cracking and improving durability.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Productivity
If the trailing edge is made thin to reduce weight and improve aerodynamic performance, then the aerodynamic efficiency is improved, but the structural strength and resistance to thermal stress deteriorate
Solution Approach 1:
The trailing edge is segmented by introducing cutbacks that divide the continuous trailing edge structure into separate sections. These cutbacks create discrete segments that can independently deform under thermal stress, preventing stress concentration while maintaining the overall aerodynamic shape. The trailing edge is divided into multiple zones with different flexibility characteristics.
Solution Approach 2:
The cutbacks introduce localized structural modifications at specific positions along the trailing edge, creating areas of controlled flexibility. The trailing edge transitions from a uniformly thin structure to one with spatially varying properties - thinner sections for aerodynamic performance and reinforced/segmented sections for stress relief. This local quality change allows the trailing edge to have different mechanical properties at different locations.
2Reliability
If cooling holes and slots are added to protect from thermal stress, then the thermal resistance is improved, but the manufacturing complexity increases
Solution Approach 1:
The cooling structure is segmented into discrete cutback features rather than requiring a dense network of cooling holes and slots throughout the trailing edge. This segmentation approach provides thermal stress relief through structural division rather than through extensive cooling channels, simplifying the manufacturing process while maintaining thermal stress resistance.
Solution Approach 2:
The patent extracts the essential function of thermal stress management from the complex cooling hole/slot system and implements it through simpler cutback geometries. By removing the need for extensive internal cooling channels in the trailing edge region and replacing them with external cutback features, the manufacturing complexity is reduced while the thermal stress protection function is retained.
3Duration of action of stationary object
If cutbacks are introduced to reduce stress concentration, then the trailing edge durability is improved, but the aerodynamic performance may deteriorate
Solution Approach 1:
The cutbacks are designed with specific dimensional characteristics that localize their stress-relief function to the immediate trailing edge region while minimizing their impact on the broader aerodynamic flow. The cutback depth, width, and positioning are optimized to provide structural benefits without creating significant flow separation or pressure distribution changes that would degrade aerodynamic performance.
Solution Approach 2:
The cutback geometry parameters (depth, width, angle, positioning) are carefully controlled and optimized to achieve the desired balance between stress relief and aerodynamic performance. By adjusting these parameters, the design achieves sufficient flexibility for stress management while maintaining the aerodynamic shape integrity in the regions most critical for flow attachment and pressure distribution.
Data Source
AI summary
Disclosed is a turbine vane having an airfoil in a cross section including a leading edge, a trailing edge, and a pressure surface and a suction surface connecting the leading edge and the trailing edge, the airfoil extending radially from a platform part to an end wall, wherein the trailing edge of the airfoil is provided with a cutback cut in a direction radially perpendicular to both the pressure surface and the suction surface.