Variable Setting Vane Noncircular Platform Friction Reduction
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Solution Overview
Problem
The existing variable-pitch vane stator stages in turbomachines suffer from high wear of parts, particularly the edges of the groove and the ring, leading to increased friction and reduced service life due to aerodynamic forces and frictional wear, resulting in frequent replacement of the ring and reduced blade life.
Innovation Solution
The design introduces a radially internal platform with a non-circular contour, featuring a peripheral shrinkage to reduce friction with the housing orifice, maintaining small clearances and minimizing aerodynamic recirculations, while maintaining the same stress levels as new blades, thus extending the service life of the ring and blades.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If a circular radially internal platform is used, then the blade can be properly centered and supported, but friction and wear occur between the platform and the housing orifice, reducing service life
Solution Approach 1:
The radially internal platform is designed with a non-circular contour that is asymmetric relative to the blade rotation axis. This asymmetric shape creates variable clearances between the platform and the housing orifice, with larger clearances positioned to reduce friction during operation, thereby resolving the contradiction between proper centering support and friction reduction.
Solution Approach 2:
The platform contour is modified locally by introducing a peripheral shrinkage or indentation at specific locations. This local geometric modification creates increased clearance in critical areas where friction occurs, while maintaining adequate contact and support in other areas, thus locally reducing friction and wear without compromising overall structural support.
2Reliability
If the platform contour is modified to reduce friction, then wear is reduced, but aerodynamic recirculations may be affected
Solution Approach 1:
The asymmetric non-circular contour is designed with careful consideration of aerodynamic flow patterns. The shrinkage or indentation is positioned and dimensioned to reduce friction in critical areas while maintaining smooth transitions that minimize flow separation and aerodynamic recirculations, thus balancing wear reduction with aerodynamic performance.
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 design reduces friction and wear, increasing the service life of the ring and blades, while maintaining the original stress levels and minimizing impact on the aerodynamic flow, thereby enhancing the durability and performance of the turbomachine components.
Implementation Method 1
The design introduces a radially internal platform with a non-circular contour, featuring a peripheral shrinkage to reduce friction with the housing orifice
Data Source
Figure 1~2
Figure 3
Figure 4~5
AI summary
The invention relates to a variable setting vane (8) for a rectifier stage, including a blade (43) on either side of which are provided a radially inner platform (13) and a radially outer platform, the blade (43) having a surface (64) defining a suction side and a surface (62) defining a pressure side and separating the platform (13) into a portion (13a) arranged on the suction side and a portion (13b) arranged on the pressure side. According to the invention, and following the direction of the vane rotational axis (20), the portion (13a) has an outer outline (Ca) vertically adjacent to a circle (C1), remote from which and inside which at least a portion (Cb1) of the outer outline (Cb) of the portion (13b) of the platform (13) is located.