Gas Turbine Shroud Segment Contact Surface Optimization
Find Innovative SolutionsGenerate Solutions
Solution Overview
Problem
Gas turbine blades deform under centrifugal forces, high temperatures, and pressures, leading to significant changes in geometry that cause high compressive stresses at contact surfaces between shroud segments, potentially resulting in plastic deformation, material flow, or welding, which reduces blade life and complicates maintenance.
Innovation Solution
A method involving a 3D model of the blades to calculate and optimize the geometry of contact surfaces, accounting for operational loads, ensuring approximate parallelization of locking surfaces during deformation to distribute compressive stresses and maintain tightness, by determining the necessary geometry in both loaded and unloaded states.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Ease of manufacture
If the shroud segments are designed with parallel locking surfaces in the unloaded state, then the manufacturing is simplified, but high compressive stresses occur at the contact surfaces during operation due to blade deformation
Solution Approach 1:
The locking surfaces are pre-shaped in the unloaded state with specific non-parallel geometry (wedge surfaces and curved surfaces) so that when the blade deforms under operational loads, the surfaces automatically align to become approximately parallel, distributing compressive stresses over a larger area and avoiding stress concentration
Solution Approach 2:
The geometry of the locking surfaces is optimized by considering the deformed state of the blade. The contact surfaces are designed with specific curvature radii and wedge angles that change from the unloaded to the loaded state, transforming the stress distribution characteristics to achieve both manufacturing feasibility and stress reduction
2Manufacturing precision
If the contact surfaces are made narrow to achieve precise alignment, then the manufacturing precision is improved, but the compressive stresses increase due to smaller contact area
Solution Approach 1:
The locking surfaces are designed with curvature in multiple dimensions (cylindrical surfaces with specific radii, wedge surfaces with gradual angles) so that the contact evolves from a narrow line in the unloaded state to a broader area in the loaded state, achieving both precision and stress distribution
3Strength
If the shroud segments are allowed to deform freely under operational loads, then the blade can accommodate thermal and mechanical stresses, but the tightness between adjacent shroud segments is compromised
Solution Approach 1:
The locking surfaces are designed with asymmetric geometry relative to the blade axis, with different curvature radii and wedge angles on opposite sides, creating a mechanical interlock that maintains tightness while accommodating deformation through controlled elastic compliance
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
This approach effectively avoids high compressive stresses and maintains tightness between shroud segments, enhancing blade life and facilitating maintenance by optimizing contact surfaces based on deformation behavior and operational conditions.
Implementation Method 1
taking into account the centrifugal forces, temperature loads, pressure loads of the blade that occur during operation
Implementation Method 2
An optimized design of the contact surfaces of the abutting shroud segments (14) of adjacent blades (10, 10') in the loaded state of the blades (10, 10') reaching operating temperature
Data Source
Figure 1
Figure 2
Figure 3~4D
AI summary
The invention relates to a method for optimizing the contact surfaces of shroud segments (14), which abut against one another, of adjacent blades (10, 10') of a rotor blade row of a gas turbine. Said optimization is achieved by means of a series of steps, specifically: a 3D model of the individual blades (10, 10') is firstly provided. A calculation of the geometry of the individual blades (10, 10') is then carried out on the basis of the provided 3D model taking into consideration at least the centrifugal and/or temperature and/or pressure loadings of the blade which occur during operation. An optimization of the contact surfaces of the shroud segments (14), which abut against one another, of adjacent blades (10, 10') in the loaded state of the blade (10, 10') then takes place, said optimization relating to those contact surfaces which serve functionally as locking surfaces (F2, F2') and relating to those contact surfaces which are arranged at both sides of the locking surfaces and which serve functionally as wedge surfaces (F1, F1'; F3, F3'). Finally, the required geometry of the locking surfaces (F2, F2') and of the wedge surfaces (F1, F1'; F3, F3') in the unloaded state of the blades (10, 10') is determined.