Gas Turbine Positioning Element Recesses Mitigate Cording
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Solution Overview
Problem
The cording effect in positioning elements of gas turbine guide vane stages causes significant deformations and wear due to thermal conditions, leading to sealing issues and reduced efficiency.
Innovation Solution
Incorporating recesses in the base section of the positioning element between receiving openings, which reduces the effective radial height and flexural rigidity, thereby mitigating the cording effect and enhancing the durability of sealing elements.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Strength
If the positioning element is made as a continuous ring structure, then the structural strength is improved, but the cording effect increases due to thermal expansion
Solution Approach 1:
The positioning element is divided into multiple segments by introducing recesses between the receiving openings. These recesses create discontinuities in the ring structure that allow controlled deformation, reducing the cording effect while maintaining overall structural integrity. The segments can expand and contract independently in response to thermal gradients.
Solution Approach 2:
The recesses are strategically positioned between receiving openings to create localized areas of reduced rigidity. This allows the positioning element to have different mechanical properties in different regions - stronger where needed for structural support and more compliant where thermal expansion occurs, thereby reducing the harmful cording effect.
2Object-affected harmful factors
If recesses are provided in the base section, then the cording effect is reduced, but the structural rigidity decreases
Solution Approach 1:
The recesses segment the continuous ring structure into controlled sections. This segmentation reduces the overall flexural rigidity to allow thermal expansion without excessive cording, while the remaining material between recesses maintains sufficient local strength to support the guide vanes and sealing elements.
Solution Approach 2:
The depth, width, and distribution of the recesses are carefully controlled to achieve the desired balance between reducing cording effect and maintaining adequate rigidity. By adjusting these geometric parameters, the positioning element can be optimized for specific thermal and mechanical loading conditions.
3Object-affected harmful factors
If the positioning element is made softer to reduce cording effect, then the wear on sealing elements is reduced, but the ability to maintain precise positioning may deteriorate
Solution Approach 1:
The segmented structure with recesses allows the positioning element to be softer overall while maintaining localized precision. The recesses provide compliance to reduce wear, while the remaining structural portions between recesses maintain the necessary positioning accuracy for the guide vanes.
Solution Approach 2:
Different regions of the positioning element have different mechanical properties - the recess areas are softer to reduce cording and wear, while the areas between recesses maintain higher rigidity to ensure precise positioning. This spatial variation in material properties resolves the contradiction between softness and precision.
Applied Scientific Principles
This section explains which scientific principles are used to turn an abstract innovation direction into a practical engineering solution.
Function Achieved in This Case
The reduced cording effect minimizes constrictions and leakages, improving the efficiency and surge limit of the gas turbine, while also extending the durability of sealing elements and reducing maintenance costs.
Implementation Method 1
due to the thermal conditions, a radial temperature gradient forms in the positioning half rings, with the positioning half rings being subject to greater expansion in the circumferential direction radially on the outside than radially on the inside
Data Source
Figure 1~2
Figure 3~4
Figure 5~6B
AI summary
The invention relates to a positioning element (10) for a guide vane assembly of a guide vane stage of a gas turbine, comprising at least one circumferentially curved (UR) base section (12); several receiving openings (14) arranged adjacent to one another in the circumferential direction (UR) on the base section (12), the opening axis of which extends substantially in the radial direction and which are configured to receive a respective radially inner guide vane section; and a coupling section (18) provided on the base section (12), which can be coupled to or is coupled to a sealing carrier of a sealing assembly. According to the invention, it is proposed that at least one recess (16) be provided in the base section (12), which is arranged between two adjacent receiving openings (14) and extends at least in the radial direction (RR) from the inside to the outside.