Turbine Blade Intermediate Wall Elasticity
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Solution Overview
Problem
Turbine blades in gas turbines experience fatigue and crack formation due to thermomechanical stresses caused by high temperature differences between the hot gas-exposed leading edge and the cooling air-exposed inner walls, leading to reduced service life.
Innovation Solution
The turbine blade design incorporates a perforated intermediate wall with a curved or 'V' or 'U' shaped cross-section, allowing for elasticity and flexibility to accommodate thermal expansion and shrinkage, reducing mechanical stresses and improving heat transfer.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Strength
If a rigid intermediate wall is used to connect suction and pressure sidewalls, then structural strength is improved, but thermomechanical stresses increase due to thermal expansion constraints
Solution Approach 1:
The intermediate wall is designed with a curved or V-shaped/U-shaped cross-section instead of a straight rigid structure. This flexible geometry allows the wall to deform elastically in response to thermal expansion and contraction of the blade materials, reducing thermomechanical stresses while maintaining structural integrity.
Solution Approach 2:
The intermediate wall's geometric parameters are optimized by introducing curvature (V-shape or U-shape) rather than a straight configuration. This parameter change enables the wall to accommodate thermal deformations through elastic yielding, transforming the rigid structure into a stress-relieving flexible element.
2Temperature
If cooling air supply is increased to improve heat resistance, then cooling effectiveness is improved, but thermomechanical stresses increase due to larger temperature differences
Solution Approach 1:
The flexible intermediate wall structure accommodates the thermal deformations that occur when cooling air supply is increased. By allowing elastic deformation, the wall prevents stress concentration that would otherwise result from the temperature differences between cooled and uncooled regions.
Solution Approach 2:
The intermediate wall is designed to exploit thermal expansion principles by allowing controlled elastic deformation in response to temperature changes. The curved/V-shaped/U-shaped geometry provides the necessary compliance to handle differential thermal expansion between the suction and pressure sidewalls without generating excessive stresses.
3Ease of manufacture
If straight intermediate wall is used for simplicity, then manufacturing ease is improved, but heat transfer and elasticity are reduced
Solution Approach 1:
The intermediate wall is designed with curved or V-shaped/U-shaped cross-sections instead of straight geometry. This curvature increases the surface area available for heat transfer and provides elastic compliance to accommodate thermal deformations, while remaining manufacturable through standard casting or additive manufacturing processes.
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 design effectively reduces fatigue-related crack formation by allowing the intermediate wall to yield to thermal changes, maintaining the known cooling measures' effectiveness while enhancing the blade's durability and heat transfer capabilities.
Implementation Method 1
allowing for elasticity and flexibility to accommodate thermal expansion and shrinkage
Implementation Method 2
The intermediate wall has perforations, at least in sections, in the area connecting to the suction and/or pressure side walls to increase elasticity
Implementation Method 3
cooling air is supplied to this cavity from the blade root... improve heat transfer between the blade wall and the cooling air flow
Data Source
Figure 1
Figure 2~3c
Figure 4a~4d
AI summary
A turbine vane for a rotary turbomachine is described having a turbine blade (4) which is delimited by a concave pressure-side wall (6) and a convex suction-side wall (7) which are connected in the region of a vane front edge (5) which can be assigned to the turbine blade (4) and enclose a cavity (9) which extends in the longitudinal extent of the vane front edge (5) and is delimited on the inner wall by the pressure-side wall (6) and the suction-side wall (7) in the region of the vane front edge (5) and by an intermediate wall (8) which extends in the longitudinal direction to the vane front edge (5) and connects the suction-side wall (7) and the pressure-side wall (6) on the inner wall. The disclosed vane is distinguished by the fact that the intermediate wall (8) has a perforation (16) at least in sections in the connecting region to the suction-side wall (7) and/or pressure-side wall (6), in order to increase the elasticity of the intermediate wall (8).