Turbine Blade Stilt Segmentation for Mass Reduction
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Solution Overview
Problem
Conventional moving blades of low-pressure turbines face challenges in meeting mechanical stresses due to the limitations of rectilinear stilts, which can lead to increased mass and inefficiency, especially in complex geometric configurations.
Innovation Solution
A moving blade design featuring a stilt with a segmented cross-section comprising rectilinear and curvilinear parts, where the curvilinear part has a high overlap with the blade's cross-section, allowing adjustable lengths to optimize mechanical characteristics and reduce weight, achieved through CAD modeling and thermomechanical calculations.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Strength
If curvilinear stilts are used to match the blade profile, then mechanical stress distribution is improved, but blade mass increases
Solution Approach 1:
The stilt is divided into multiple segments with different cross-sectional shapes: a first portion with a first cross-sectional shape, a second portion with a second cross-sectional shape, and a third portion with a third cross-sectional shape. This segmentation allows each portion to be optimized for its specific functional requirements, achieving good stress distribution while controlling overall mass.
Solution Approach 2:
Different portions of the stilt have different cross-sectional shapes tailored to their local requirements. The first portion has one shape optimized for its position, the second portion has another shape for its position, and the third portion has a third shape. This local differentiation optimizes mechanical performance at each location without uniformly increasing the entire blade's mass.
2Weight of moving object
If rectilinear stilts are used, then blade mass is reduced, but mechanical stress requirements are not met in complex geometric configurations
Solution Approach 1:
Rather than using a single rectilinear stilt shape that fails to meet stress requirements, the invention segments the stilt into multiple portions with different cross-sectional shapes. This allows the design to achieve adequate stress resistance in complex geometric configurations while maintaining lower mass compared to a fully curvilinear design.
Solution Approach 2:
The stilt employs asymmetric cross-sectional shapes that are specifically tailored to the local geometric configuration and stress requirements at each portion. This asymmetric design allows optimization for both strength and weight, rather than using symmetric rectilinear or curvilinear shapes.
Data Source
Figure 1~3
AI summary
The invention concerns a moving blade (1) of a low pressure turbine having a foot (10) and a vane (30) having an upper surface (31) and a lower surface (32), said foot (10) having a stilt (11) linking the vane (30) to the foot (10): said blade (1) being characterised in that said stilt (11) is formed such that the transverse section of said stilt has: a first straight portion (14), a second curved portion (15) and a third straight portion (16), said curved portion (15) having an outer face (18) matching the profile of the upper surface (31) of said vane (30) and an inner face (17) matching the profile of the lower surface (32) of said vane (30).